CN117483666A - Preparation method of ceramic shell for precision casting - Google Patents
Preparation method of ceramic shell for precision casting Download PDFInfo
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- CN117483666A CN117483666A CN202311464857.4A CN202311464857A CN117483666A CN 117483666 A CN117483666 A CN 117483666A CN 202311464857 A CN202311464857 A CN 202311464857A CN 117483666 A CN117483666 A CN 117483666A
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Abstract
In order to solve the problems in the prior art, the invention provides a preparation method of a ceramic shell for precision casting, which comprises the following steps: s1, coating ceramic shell slurry with the corresponding layers layer by layer outside the wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed. S2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried. When the vacuum rapid drying treatment is carried out, firstly, the model information of the ceramic shell to be dried is obtained, and then, the control parameters of all the blowers at different side directions of the ceramic shell to be dried are regulated according to the model information, so that the drying time trend of all parts of the whole ceramic shell to be dried is consistent. S3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting. On the basis of retaining the inherent advantages of the thick paste ceramic shell, the invention effectively overcomes the problems of the thick paste ceramic shell.
Description
Technical Field
The invention relates to the technical field of precision casting, in particular to a preparation and drying method of a ceramic shell for precision casting.
Background
Precision casting is a casting method that can obtain a relatively accurate shape and high casting accuracy relative to conventional casting processes. The process of precision casting comprises the following steps: firstly, manufacturing a wax mould, wherein the size and shape of the wax mould are consistent with those of a product to be cast, forming a ceramic shell on the surface of the manufactured wax mould, dewaxing the ceramic shell (removing the wax mould in the ceramic shell after melting), and finally pouring a metal material into the dewaxed ceramic shell, and crushing and removing the ceramic shell after cooling and solidifying the metal material to obtain a casting, namely the required product.
In the process, the manufacture of the ceramic shell is critical, and the quality of the ceramic shell determines the quality of castings. At present, the ceramic shell is manufactured by the following general methods: the shell mold method, particularly the water-soluble silica sol shell making method, is to prepare different slurries and sand by using refractory materials, and the slurries and the sand are gradually stacked layer by layer on the surface of a wax mold to prepare the ceramic shell with required thickness. Thus, the ceramic shell can be structurally divided into a face layer, a transition layer (two layers), a support layer (back layer) and a closure layer, wherein the face layer, the transition layer and the closure layer are each one layer, and the support layer typically has multiple layers.
The ceramic shell slurry is generally divided into thick slurry ceramic shells and thin slurry ceramic shells according to the concentration of the ceramic shell slurry in the preparation process of the ceramic shells, and the concentration of the ceramic shell slurry of the thick slurry ceramic shells is higher as the name implies. The main advantages of the dense slurry ceramic shell relative to the thin slurry ceramic shell are:
1. the thickness of each layer of ceramic shell is larger, and the supporting force is higher, so that the ceramic shell supporting force which can be achieved by the thin slurry ceramic shell with a larger number of layers can be achieved by the fewer thick slurry ceramic shell layers, and the complexity of the process is reduced.
2. The ceramic shell surface layer has higher density, and the problem of casting penetration is rarely caused.
However, when preparing ceramic shells in the prior art, the main reason for choosing thin slurry ceramic shells in most cases is that thick slurry ceramic shells have the following problems that are difficult to overcome:
1. because the slurry concentration is higher, the sand material is difficult to permeate the whole slurry layer when the sand is covered, so that the uneven state that the sand is covered and polymerized on the surface layer and the inside is lost occurs, the ceramic shell has uneven strength, and the sand-free part is easy to crack when being dried, so that the cast is punctured and runs out.
2. The ceramic shell has poor air permeability, can generate the problem of unsmooth exhaust in casting, easily makes the foundry goods surface appear because the recess face that the bubble leads to, influences foundry goods precision.
3. The breaking strength coefficient is higher, and although the higher breaking strength coefficient is favorable for preparing a compact surface layer and provides enough supporting force for the casting process, the overall high breaking strength coefficient of the ceramic shell can cause difficulty in breaking and taking a piece after casting is finished, and the casting is easily damaged when violent breaking is adopted, so that the casting precision is reduced. Therefore, on the basis of ensuring that the ceramic shell has enough supporting force, the ceramic shell has lower breaking strength coefficient, which is always a technical improvement direction in the field of precision casting.
4. The thick slurry ceramic shell has lower water content but has larger water molecule movement resistance, so the drying time is even longer than that of the thin slurry, and when castings with deep holes are involved, the drying time tends to be consistent in all parts of the ceramic shell, and when the drying of the ceramic shell in the deep holes is finished, the other parts of the ceramic shell can be overdry, so that the ceramic shell is cracked.
However, the thickness of the thin ceramic shell has a limit due to the expansion of the thickness of a single layer, when the breaking strength coefficient is low, the thickness of the ceramic shell has to be increased by increasing the number of layers to provide enough supporting force, so that the ceramic shell needs to be sized for multiple times, the process complexity is improved, the drying time of the ceramic shell is increased along with the improvement of the number of layers, and the preparation efficiency is obviously reduced. Meanwhile, when the deep hole casting is concerned, how to make the drying time of each part of the grout Tao Ketao shell consistent and complete the drying in a shorter time is also a technical problem to be overcome.
Disclosure of Invention
The invention provides a preparation method of a ceramic shell for precision casting, aiming at the problems existing in the prior art, comprising the following steps:
s1, coating ceramic shell slurry with the corresponding layers layer by layer outside the wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed.
S2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried.
When the vacuum rapid drying treatment is carried out, firstly, the model information of the ceramic shell to be dried is obtained, and then, the control parameters of all the blowers at different side directions of the ceramic shell to be dried are regulated according to the model information, so that the drying time trend of all parts of the whole ceramic shell to be dried is consistent.
S3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting.
Further, the ceramic shell slurry is prepared by compounding ceramic shell sol, powder, water and sand, and meets the following requirements:
the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 55-60 seconds, the concentration of the transition ceramic shell slurry is 30-35 seconds, the concentration of the support ceramic shell slurry is 22-25 seconds, the concentration of the sealing ceramic shell slurry is 10-12 seconds, and the sealing layer does not contain sand.
Further, the sand material is added into a mixed system of ceramic shell sol, powder and water in a sand coating treatment mode, and the sand coating treatment comprises the following steps: and (5) sand spraying treatment or floating sand treatment.
Further, 100-mesh sand is selected when the surface layer is coated with sand, 60-mesh sand is selected when the transition layer is coated with sand, and 35-22-mesh sand is selected when the support layer is coated with sand.
Further, the sand spraying treatment comprises the following steps:
firstly, sand spraying treatment is carried out on the ceramic shell to be dried for the first time at a height position 10 cm to 30cm away from the ceramic shell to be dried.
And then, carrying out second to Nth sand spraying treatment, and gradually lifting the sand spraying height by 3-5cm compared with the sand spraying treatment of the last time until the sand spraying treatment is finished.
Further, the floating sand treatment comprises:
firstly, putting a ceramic shell to be dried into a floating sand machine, and starting the floating sand fan to enable sand materials in the floating sand machine to float and cover the surface of the ceramic shell to be dried.
And stopping the floating sand blower to enable sand materials in the floating sand blower to be static and stacked around the ceramic shell to be dried, and standing for a period of time.
Repeating the two steps until the floating sand treatment is completed.
Further, the vacuum flash drying system includes: a vacuum drying cavity, a vacuum pump and a control system. And the vacuum pump performs vacuumizing treatment on the vacuum drying cavity. The vacuum pump is communicated with the vacuum drying cavity through a first connecting pipe, and a first electric control switch valve is arranged on the first connecting pipe. The vacuum drying cavity is communicated with an air pipe, and a second electric control valve is arranged on the air pipe.
The drying rack is detachably arranged in the vacuum drying cavity, and the ceramic shell to be dried is detachably arranged on the drying rack so as to be dried. At least two groups of fan units with different wind directions are arranged around the drying frame in the vacuum drying cavity.
The control system includes: the vacuum drying control module and the fan set control module. The vacuum drying control module controls the opening and closing of the vacuum pump, the first electric control switch valve and the second electric control valve, and the fan set control module controls the opening and closing and/or control parameters of all fan sets.
Further, a first blower unit is arranged at the top of the drying frame in the vacuum drying cavity, a second blower unit is arranged at the bottom of the drying frame, a third blower unit is arranged on the vacuum drying cavity switch door along the cutting direction of the drying frame, and a fourth blower unit and a fifth blower unit are respectively arranged at two sides of the drying frame along the axial direction of the vacuum drying cavity.
Further, an adjustable component is arranged in the vacuum drying cavity at the opposite side of the third blower unit. The adjustable component is as follows: a condenser or a sixth blower unit.
Optionally, the vacuum drying chamber is provided with a controller assembly. The controller component receives control signals and sends the control signals to the fan group control module so as to control the on-off and/or control parameters of each fan group.
Further, the controller includes: at least one of a knob controller, a key controller, a touch screen controller and a toggle switch.
Optionally, a three-dimensional detection mechanism is arranged in the vacuum drying cavity. The three-dimensional detection mechanism drives the scanning device to move along the X axis, the Y axis and the Z axis.
The scanning device at least comprises: an image pickup device. The camera device is used for acquiring image data of the ceramic shell to be dried.
The control system includes: and a ceramic shell analysis module. And the ceramic shell analysis module acquires image data of the ceramic shell to be dried and performs model structure analysis to obtain the position, the orientation and the depth of a deep hole of the ceramic shell to be dried, and sends the deep hole to the fan set control module. And after the fan set control module performs fan set control analysis according to the deep hole position, the direction and the depth of the ceramic shell to be dried, controlling the opening and closing and/or control parameters of each fan set according to the analysis result.
Further, the three-dimensional detection mechanism includes: two X-axis guide rails which are parallel to each other and are respectively positioned at two sides of the drying frame are horizontally arranged along the axial direction of the vacuum drying cavity, and Y-axis guide rails which are horizontally arranged along the cutting direction of the vacuum drying cavity. The X axial guide rails are respectively provided with a first displacement device capable of displacing along the X axial guide rails, and the Y axial guide rails are fixed between the two first displacement devices and are driven by the two first displacement devices to displace along the X axial guide rails. And the Y-axis guide rail is provided with a second displacement device capable of displacing along the Y-axis guide rail. And an electric control telescopic device which stretches along the Z-axis direction is arranged on the displacement device along the vertical direction. The tail end of the telescopic end of the electric control telescopic device is fixed with a scanning device through an electric control cradle head. The first displacement device, the second displacement device, the electric control telescopic device and the electric control cradle head are respectively connected with the control system through signals.
Further, the control system includes: and a scanning device control module. The scanning device control module is used for controlling the movement of the two first displacement devices, the second displacement devices, the electric control telescopic devices and the electric control cradle head so that the scanning device can carry out omnibearing shooting/scanning on the ceramic shell to be dried to obtain image/scanning data of the ceramic shell to be dried.
Further, the model structure analysis includes image analysis:
firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of a ceramic shell to be dried.
And then comparing the acquired image data with the outer contour model data, and determining the spatial orientation of the ceramic shell to be dried in the vacuum drying cavity.
And finally, determining the current deep hole position and orientation of the ceramic shell to be dried according to the space orientation of the ceramic shell to be dried, and outputting the current deep hole position and orientation of the ceramic shell to be dried and depth data corresponding to the deep hole.
Further, the scanning device further includes: scanning the distance measuring device. The scanning distance measuring device is used for measuring the distance between the ceramic shell to be dried and the scanning device in real time.
The model structure analysis includes:
step 1.1, the scanning ranging device performs omnibearing scanning on the surface n of the ceramic shell to be dried according to a preset line to obtain a ranging data set Gn of all scanning points of the surface n relative to the scanning ranging device.
And 1.2, connecting the tail end points of the ranging data set Gn to obtain a digital surface m of the surface n of the ceramic shell to be dried.
And 1.3, carrying out graphic analysis on the digital surface m of the ceramic shell to be dried by combining the image data, and determining the basic surface, the convex surface and the concave surface of the digital surface m.
Step 1.4, calculating a difference Cmk-b of each ranging point in the groove surface relative to each ranging point of the adjacent basic surface of the groove, wherein mk is a groove with a number k on the digital surface m, and b is an additional number of the ranging point in the groove mk.
Step 1.5, cmk-b > K2 is taken as a deep hole, and Cmk-b > K3 is taken as a through hole. Wherein K2 is a preset deep hole judgment threshold value, and K3 is a model width or a model length or a model height corresponding to the surface n of the ceramic shell to be dried.
And 1.6, counting the positions Wmc of all deep holes on the digital surface m of the ceramic shell to be dried and the depth Hmc corresponding to each deep hole, wherein c is the natural number of the deep holes on the digital surface m.
Step 1.7, repeating the steps 1.1 to 1.6 until the positions Wmc and the depths Hmc of deep holes on the surface of the ceramic shell to be dried, which can be scanned completely, are counted, and determining the orientation Xmc of the deep holes according to the surface n of the deep holes.
And step 1.8, outputting data of positions Wmc, depths Hmc and orientations Xmc of deep holes on the whole surface of the ceramic shell to be dried.
Further, the method for obtaining the basic surface, the convex surface and the concave surface in the step 1.3 includes:
and 1.3.1, acquiring image data corresponding to the digital surface m of the ceramic shell to be dried, and splicing the image data to obtain an image surface R.
Step 1.3.2, element recognition is performed on the image plane R to obtain element regions rn-m on the image plane R, wherein rn is the sequence number of the element regions in the digital surface m.
Step 1.3.3 the digital surface m is adjusted to the same orientation and similar size as the image plane R.
Step 1.3.4 takes an element region rc-m with the largest continuous area as a basic surface, wherein the rc-m belongs to rn-m.
And 1.3.5, acquiring distance measurement point data of each non-basic surface element area, wherein element area distance measurement points with a distance greater than that of adjacent basic surface distance measurement points are groove points, and element area distance measurement points with a distance less than that of adjacent basic surface distance measurement points are raised points.
Step 1.3.6, using the element area as a boundary, connecting adjacent groove points and protruding points to form a groove surface and a protruding surface.
Further, the electric control cradle head comprises: and the rotating table is rotationally connected with the fixed table and rotates along a vertical shaft relative to the fixed table. The rotating table is rotationally connected with the fixed end of the second electric control telescopic device through a speed reducer, and the speed reducer controls the second electric control telescopic device to rotate along the horizontal shaft. And the telescopic end of the second electric control telescopic device is fixed with the scanning device.
Further, the model structure analysis further includes:
and 2.1, controlling the scanning distance measuring device to move to the deep hole position according to the deep hole position.
And 2.2, acquiring a plurality of deep hole depth measurement data by adjusting the orientation of the scanning distance measuring device relative to the deep holes.
And 2.3, correcting the depth data Hm-c of the original deep hole by using the depth measurement data with the deepest depth to obtain corrected data Hm-c'.
Further, the scanning device further includes: an infrared temperature measuring device. The control system includes: and the drying process analysis module is used for acquiring the measurement quantity of the infrared temperature measuring device to carry out drying process analysis so as to judge whether the ceramic shell to be dried is dried.
The drying process analysis includes: the temperature T inside the borehole is measured periodically or continuously. And (3) making a curve Qv of the deep hole temperature Tv-the drying time t, and when all the Qv have curve sections conforming to a preset curve rule, indicating that the drying of the ceramic shell to be dried is completed. Wherein v is the natural number of all deep holes of the ceramic shell to be dried.
Further, the preset curve rule includes: the temperature T in the deep hole gradually decreases to a temperature T2 along with the drying time from the initial drying temperature T1, then gradually increases to the environment drying temperature T3 along with the drying time, and when the temperature T of the deep hole of the ceramic shell to be dried is T1-T2-T3 and the environment drying temperature T3 is maintained for a preset time U, the completion of drying is judged. The initial drying temperature T1 is 22-26 ℃, the temperature T2 is 5-7 ℃ lower than the temperature T1, and the ambient drying temperature T3 is 24+/-1 ℃.
Further, when the ceramic shells to be dried in the same batch are plural, detecting the temperatures of all deep holes of all the ceramic shells to be dried one by one, and when more than L% of the ceramic shells to be dried are dried, judging that the whole batch of ceramic shells to be dried are dried. The ratio of L% = (Lg-d)/(L0-d) is 100%, wherein Lg-d is the number of ceramic shells to be dried after the drying of the batch d, and L0-d is the number of all ceramic shells to be dried in the batch d. Wherein the value of L% is as follows: 100 percent or more, L percent or more, E percent or more. Wherein E is a preset threshold for the lowest drying completion percentage of all ceramic shells to be dried in batch d.
Further, the fan set control analysis includes:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells to be dried, the following method is adopted:
step 3.1, obtaining the total number D0 of all deep holes of the ceramic shell to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell to be dried of the facing fan group p; the P is a fan set number arranged on different sides in the vacuum drying cavity;
step 3.2, calculating kS-p% = Dp/D0 x 100%, where kS-p% is a control parameter of fan set p;
step 3.3 repeating steps 3.1 to 3.2 to obtain kS-p% for all the fan sets;
for all the fan groups p facing the surface of the ceramic shell to be dried without deep holes, the following method is adopted:
Calculating kF-p% = [ 1-D0/(D0+1) ], wherein kF-p% is a control parameter of the fan group p;
the fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
Further, the fan set control analysis includes:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells to be dried, the following method is adopted:
step 4.1, obtaining the total number D0 of all deep holes of the ceramic shell to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell to be dried of the facing fan group p; the P is a fan set number arranged on different sides in the vacuum drying cavity;
step 4.2, obtaining kS-p% from a control parameter database according to the number of D0 and Dp; the kS-p% is a control parameter of the fan group p;
step 4.3 repeating steps 4.1 to 4.2 to obtain the kS-p% of all the fan groups;
for all the fan groups p facing the surface of the ceramic shell to be dried without deep holes, the following method is adopted:
obtaining kF-p% from a control parameter database according to the total number D0 of all deep holes of the ceramic shell to be dried; the kF-p% is a control parameter of the fan group p;
the fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
Further, k is recorded in a control parameter database S-p The% and kF-p% method includes:
step 5.1 simulates the same fan set position and orientation as the target vacuum drying chamber 1 in the simulation device.
Step 5.2, presetting deep hole distribution conditions of different ceramic shells 4 to be dried for drying training, and determining control parameters k of each fan set p corresponding to optimal drying time under each deep hole distribution condition when the fan set p is relatively fully loaded S-p % and kF-p%; the deep hole distribution condition comprises: deep hole orientation and number; the optimal drying time is the shortest time for synchronously drying deep holes and surface layers of each surface of the ceramic shell 4 to be dried;
step 5.3 repeating the step 5.2 until training of deep hole distribution under normal conditions is completed, and constructing D0-Dp-k S-p And (3) a deep hole-control parameter relation group of%kF-p% and storing the deep hole-control parameter relation group into a control parameter database.
Further, at least two fans are arranged in the fan unit. And the fan group control module synchronously controls or independently controls the fans in each group of fan groups.
Further, the fan set control analysis further includes:
and 6.1, constructing a three-dimensional coordinate system based on a scanning starting point preset by the scanning device.
And 6.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device, and marking the three-dimensional coordinate point on the position, the orientation and the depth of the deep hole of the ceramic shell to be dried in the model structure analysis process.
And 6.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fans in the fan set p.
And 6.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area.
Step 6.5 calculates kup-e% = (Dup-e/Dup) ×ks-p%.
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load.
Further, the fan set control analysis includes:
and 7.1, constructing a three-dimensional coordinate system based on a scanning starting point preset by a scanning device.
And 7.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device, and marking the three-dimensional coordinate point on the position, the orientation and the depth of the deep hole of the ceramic shell to be dried in the model structure analysis process.
And 7.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fans in the fan set p.
And 7.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area.
Step 7.5, acquiring kup-e% of corresponding fans from a control parameter database according to Dup and Dup-e, wherein kup-e% are control parameters of fans with numbers e in the fan group p.
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load.
Further, the kup-e% obtaining method comprises the following steps:
step 8.1 simulates the same fan set position and orientation as the target vacuum drying chamber in a simulation device.
And 8.2, presetting deep hole distribution conditions of different ceramic shells to be dried for drying training, and determining the running proportion kup-e% of each fan in each fan group p corresponding to the optimal drying time under each deep hole distribution condition when each fan is fully loaded. The deep hole distribution condition comprises: deep hole orientation and number. The optimal drying time is the shortest time for the deep holes and the surface layers of each surface of the ceramic shell to be dried synchronously.
And 8.3, repeating the step 8.2 to the conventional deep hole distribution condition training, constructing a deep hole-control parameter relation group of Dup-e-kup-e%, and storing the deep hole-control parameter relation group in a control parameter database.
Further, the vacuum flash drying system includes: the system comprises a first data transmission module, a local database module and a remote system module.
The first data transmission module is connected with the remote system module through a signal line or a wireless network.
The local database module is used as a control parameter database for storing related deep hole-control parameter relation groups.
And the remote system module collects deep hole-control parameter relation groups of each vacuum quick drying system through the first data transmission module, and selects the optimal control parameters from the same deep hole relation to obtain the optimal deep hole-control parameter relation group under the deep hole relation. And synchronizing the optimal deep hole-control parameter relation set to the local database module of each vacuum quick drying system through the first data transmission module based on the authorization permission and/or the instruction and/or the automatic synchronization mode.
When the vacuum quick drying system calls the deep hole-control parameter relation group in the local database module, if the optimal deep hole-control parameter relation group exists, the optimal deep hole-control parameter relation group is preferentially called.
Further, the vacuum flash drying system comprises a second data transmission module and a remote system.
The remote system is connected with a control system signal of the vacuum quick drying system through a second data transmission module in a signal line connection or wireless network connection mode, so as to send remote control instructions to the control system and/or acquire control instructions sent by the control system and/or acquire operation state parameters of various electric control devices in the vacuum quick drying system.
The execution priority of the remote control instruction sent by the remote system is higher than the execution priority of the control instruction sent by the control system.
Further, the drying rack includes: the ceramic shell hanging frame is used for hanging the ceramic shell to be dried. The ceramic shell hanging rack is provided with a plurality of hooking grooves. The ceramic shell to be dried is hooked at the hooking groove through the lifting hook. The bottom of the ceramic shell hanging frame is fixedly provided with a hanging frame support plate. The bottom of the hanger support plate is provided with a plurality of rollers capable of sliding along the guide rail. The guide rail is fixed on the bottom surface of the vacuum drying cavity.
Further, a limiting block is arranged on one side, far away from the vacuum drying cavity, of the guide rail.
Further, the scanning device includes: a thermal imager. The method for enabling the drying time of all parts of the whole ceramic shell to be dried to be consistent comprises the following steps:
and 9.1, carrying out real-time thermal imaging shooting on the ceramic shell to be dried along with a scanning device by a thermal imager in the ceramic shell drying process to be dried, and sending the shooting to a control system.
And 9.2, the control system judges whether an area T with the temperature difference exceeding a preset temperature difference threshold exists according to the thermal imaging graph when the drying time exceeds the preset first drying time according to the heat distribution condition in the thermal imaging graph, and if the area T exists, the control system judges and operates as follows:
And when the temperature of the low-temperature area of the area T is lower than a preset low-temperature threshold value, reducing the operation power of the fan set corresponding to the area T.
And when the temperature of the high-temperature area of the area T is higher than a preset high-temperature threshold value, increasing the operating power of the area T corresponding to the fan set.
When the existence time of the area T exceeds a preset time threshold, the temperature of a low-temperature area of the area T is higher than a preset low-temperature threshold, and the temperature of a high-temperature area of the area T is lower than a preset high-temperature threshold, the operation power of the area T corresponding to the fan set is increased.
Further, the preset low temperature threshold is 12-15 ℃, the preset high temperature threshold is 26-28 ℃, the preset first drying time is 1-3 minutes, and the preset time threshold is 30-60 seconds.
Further, the method for vacuum rapid drying treatment comprises the following steps:
drying the surface layer: firstly, the vacuum degree of the environment of the ceramic shell to be dried is reduced to 750-720 mmHg from normal pressure within 5 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 5 seconds from 750 to 720 mmHg. And (5) circulating the process until the surface layer is dried.
When the transition layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 720-680 mmHg within 7 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 7 seconds from 720 to 680 mmHg. And (5) repeating the above process circularly until the transition layer is dried.
When drying the support layer, the method comprises the following steps:
step 10.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-20 mmHg within 30 seconds.
And 10.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 10.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 10.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-20 mmHg within 30 seconds.
Step 10.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 10.6 repeat steps 10.4 and 10.5 until the support layer is dried.
When the sealing layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 120-90 mmHg within 40 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 120 seconds. And (5) repeating the process circularly until the sealing layer is dried.
Further, the supporting layer is equipped with at least three-layer from the transition layer to the closure layer in proper order, wherein:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 11.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
And 11.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes.
Step 11.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
Step 11.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.6 repeating steps 11.4 and 11.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 12.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
And 12.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 12.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
Step 12.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.6 repeating steps 12.4 and 12.5 until the second layer of the support layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 13.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
And 13.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 13.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
Step 13.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.6 repeating steps 13.4 and 13.5 until the third layer of the support layer is dried.
And the inner surface of the closed layer is attached to the outer surface of the third layer of the supporting layer.
Further, the vacuum flash drying system includes: a vacuum drying cavity, a vacuum pump and a control system. And the vacuum pump performs vacuumizing treatment on the vacuum drying cavity. The vacuum pump is communicated with the vacuum drying cavity through a first connecting pipe, and a first electric control switch valve is arranged on the first connecting pipe. The vacuum drying cavity is communicated with an air pipe, and a second electric control valve is arranged on the air pipe.
And placing the ceramic shell to be dried into a vacuum drying cavity for vacuum rapid drying treatment.
The control system controls the opening and closing of the vacuum pump, the first electric control switch valve and the second electric control valve to realize the method steps of the vacuum quick drying treatment.
Further, the vacuum rapid drying system further comprises: and (5) a vacuum tank. One end of the vacuum tank is communicated with the vacuum pump through a second connecting pipe, and a third electric control valve is arranged on the second connecting pipe. The other end of the vacuum tank is communicated with the vacuum drying cavity through a third connecting pipe 7, and a fourth electric control valve is arranged on the third connecting pipe 7.
Further, when vacuum drying is performed on the supporting layer and the sealing layer, the method further comprises instant depressurization operation. The transient step-down operation includes:
first, before depressurization, the fourth electrically controlled valve is closed, and the vacuum tank is previously evacuated to a low vacuum state.
Then, when the pressure is reduced, a fourth electric control valve is opened, so that the vacuum drying cavity is communicated with the vacuum tank, and the pressure is instantaneously reduced to the equilibrium low pressure within 0.5 seconds.
And finally, the vacuum pump simultaneously pumps the gas phase components in the vacuum tank and the vacuum drying cavity, so that after the vacuum degree in the vacuum drying cavity accords with a preset target, the fourth electric control valve and the first electric control switch valve are closed, and the vacuum pump continuously pumps the gas phase components in the vacuum tank to a low vacuum state.
Further, the supporting layer is equipped with at least three-layer from the transition layer to the closure layer in proper order, wherein:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
and 14.1, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, and maintaining the vacuum pumping of the vacuum tank.
And 14.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank.
And 14.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank.
And 14.4, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, and maintaining the vacuum pumping of the vacuum tank.
And 14.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank.
Step 14.6 repeating steps 14.4 and 14.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
And 15.1, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, and maintaining the vacuum pumping of the vacuum tank.
And 15.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank.
And 15.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing the vacuum tank.
And 15.4, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, and maintaining the vacuum pumping of the vacuum tank.
And 15.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing the vacuum tank.
Step 15.6 repeating steps 15.4 and 15.5 until the second layer of the support layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 16.1, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, while maintaining the vacuum pumping of the vacuum tank.
And step 16.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank.
And step 16.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 90 seconds, and continuously vacuumizing the vacuum tank.
And 16.4, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, while maintaining the vacuum pumping of the vacuum tank.
And step 16.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 90 seconds, and continuously vacuumizing the vacuum tank.
Step 16.6 repeating steps 16.4 and 16.5 until the third layer of the support layer is dried.
The inner surface of the sealing layer is attached to the outer surface of the third layer of the supporting layer, and when the sealing layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
and 17.1, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 260-220 mmHg within 35 seconds, and maintaining the vacuum pumping of the vacuum tank.
And 17.2, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 120 seconds, and continuously vacuumizing the vacuum tank.
Step 17.3 steps 17.1 and 17.2 are repeated until the encapsulation layer is dried.
And further, putting the ceramic shells to be dried into a vacuum quick drying system, standing for 30-120 seconds, and performing vacuum quick drying treatment.
Further, during the standing period, the vacuum rapid drying system performs low-power drying on the ceramic shell to be dried.
Furthermore, the surface layer is added with a defoaming agent accounting for 0.1 to 0.5 percent of the mass of the ceramic shell sol.
Further, the supporting layer is added with a foaming agent with the mass of 0.5-1% of that of the ceramic shell sol.
Further, the mass concentration of silicon dioxide in the mixed system of the ceramic shell sol, the powder and the water is 22-25%.
The invention has at least one of the following beneficial effects:
1. on the basis of retaining the inherent advantages of the thick slurry ceramic shell, the invention effectively solves the problems of the thick slurry ceramic shell, and provides the thick slurry ceramic shell which has the advantages of excellent layer average thickness, good air permeability, uniform sand coverage and excellent breaking strength coefficient.
2. The invention can lead the drying time of each part of the ceramic shell to be consistent through a manual control or automatic analysis control mode, and can effectively balance the drying time of the deep hole and the surface and obtain the optimal result especially when the deep hole structure with great difficulty in uniform drying is involved.
3. The invention has remote control and remote sharing capability, can synchronize the optimal fan control method to all vacuum drying systems, obviously reduces trial-and-error cost of enterprises when drying various ceramic shells, and improves the enterprise benefit.
Drawings
FIG. 1 is a schematic diagram of a vacuum flash drying system according to the present invention;
FIG. 2 is a schematic view showing the internal structure of the vacuum drying chamber of the present invention;
FIG. 3 is a schematic view showing a part of the structure of the three-dimensional detecting mechanism of the present invention;
FIG. 4 is a schematic view showing the structure of the Z-axis part of the three-dimensional detecting mechanism according to the present invention;
FIG. 5 is a schematic view of the structure of the electrically controlled pan-tilt of the present invention;
FIG. 6 is a schematic diagram of a scanning device according to the present invention;
FIG. 7 is a schematic diagram of an exemplary ceramic shell construction;
FIG. 8 is a schematic view of the scanning device of the present invention scanning the ceramic shell of FIG. 7;
FIG. 9 is a schematic diagram showing a temperature-time curve of a preset curve rule for judging whether drying is completed according to the present invention;
FIG. 10 is a schematic view of another exemplary ceramic shell construction;
in the figure: 1. a vacuum drying chamber; 101. a first blower unit; 102. a second blower unit; 103. a third blower unit; 104. a fourth blower unit; 105. a fifth blower unit; 106. an air tube; 107. a second electrically controlled valve; 108. an adjustable member; 2. a three-dimensional detection mechanism; 201. an X-axis guide rail; 202. a Y-axis guide rail; 203. a first displacement device; 204. a second displacement device 204; 205. an electric control telescopic device; 206. electric control cradle head; 2061. a fixed table; 2062. a rotating table; 2063. a speed reducer; 2064. the second electric control telescopic device; 207. a scanning device; 2071. an image pickup device; 2072. a thermal imager; 2073. scanning a distance measuring device; 2074. an infrared temperature measuring device; 3. a drying rack; 301. a guide rail; 302. a hanger support plate; 303. a roller; 304. a ceramic shell hanging frame; 305. a hooking groove; 4. the ceramic shell is to be dried; 401. deep holes; 402. a holding part; 5. a vacuum tank; 6. a fourth electrically controlled valve; 7. a third connection pipe; 8. a vacuum pump; 9. a third electrically controlled valve; 10. the first electric control switch valve; 11. and (5) a lifting hook.
Detailed Description
The invention will now be described in further detail with reference to the accompanying drawings. It should be noted that these descriptions are exemplary only and are not intended to limit the scope of the invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.
The invention provides a preparation method of a ceramic shell for precision casting, which comprises the following steps:
s1, coating ceramic shell slurry with the corresponding layers layer by layer outside the wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed.
S2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried.
When the vacuum rapid drying treatment is carried out, firstly, the model information of the ceramic shell to be dried is obtained, and then, the control parameters of all the blowers at different side directions of the ceramic shell to be dried are regulated according to the model information, so that the drying time trend of all parts of the whole ceramic shell to be dried is consistent.
S3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting.
According to the invention, through adjusting the control parameters of the blowers at different side directions of the ceramic shell to be dried, the drying time tends to be consistent at all parts of the whole ceramic shell to be dried, and especially when the deep hole structure with high difficulty in uniform drying is involved, the drying time of the deep hole and the surface can be effectively balanced.
The invention provides ceramic shell slurry, which is prepared by compounding ceramic shell sol, powder, water and sand, and meets the following conditions:
the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 55-60 seconds, the concentration of the transition ceramic shell slurry is 30-35 seconds, the concentration of the support ceramic shell slurry is 22-25 seconds, the concentration of the sealing ceramic shell slurry is 10-12 seconds, and the sealing layer does not contain sand.
The existing grout ceramic shell is generally prepared by compounding ceramic shell sol, powder, water and sand, and meets the following requirements: the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 40-50 seconds, the concentration of the transition ceramic shell slurry is 25-28 seconds, the concentration of the support ceramic shell slurry is 12-15 seconds, the concentration of the sealing ceramic shell slurry is 10-12 seconds, and the sealing layer does not contain sand.
The ceramic shell slurry provided by the invention belongs to thick slurry ceramic shells.
The invention provides a selection requirement of sand materials of each layer of a ceramic shell, which comprises the following steps: the surface layer is coated with 100 mesh sand, the transition layer is coated with 60 mesh sand, and the support layer is coated with 35-22 mesh sand.
The ceramic shell slurry of the silica sol system gradually contracts along with the loss of water in the drying process, but the ceramic shell slurry is wrapped outside the wax mould, and the shrinkage of the ceramic shell is blocked by the existence of the wax mould, so that the ceramic shell is cracked greatly. It is therefore desirable to incorporate sand of a corresponding particle size into the ceramic shell slurry to support the slurry structure, reduce the shrinkage ratio, and reduce the likelihood of large cracks. The sand material with the particle size of the example of the invention can ensure that the thick slurry ceramic shell has good structural strength and can be stretched in the vacuum drying process to form a required structural form.
The invention provides a method for adding sand into ceramic shell slurry, which comprises the following steps: the sand material is added into a mixed system of ceramic shell sol, powder and water in a sand coating treatment mode, and the sand coating treatment comprises the following steps: and (5) sand spraying treatment or floating sand treatment.
According to the invention, sand is added into the ceramic shell slurry in a sand coating treatment mode, so that the sand can enter the ceramic shell slurry to play a necessary supporting role.
The invention provides a sand spraying treatment method, which specifically comprises the following steps:
firstly, sand spraying treatment is carried out on the ceramic shell to be dried for the first time at a height position 10 cm to 30cm away from the ceramic shell to be dried.
And then, carrying out second to Nth sand spraying treatment, and gradually lifting the sand spraying height by 3-5cm compared with the sand spraying treatment of the last time until the sand spraying treatment is finished.
The existing sand spraying treatment method comprises the following steps: the ceramic shell is sprayed with sand at a certain height, the sand spraying height is constant relative to the ceramic shell, the sand spraying height must be accurately mastered when sand spraying is carried out, the sand spraying height is too high, the Sha Liao impact force is large, although sand materials can penetrate into the ceramic shell, the problem of penetrating the ceramic shell easily occurs, the sand materials are enriched on the surface of the inner layer of the ceramic shell, if a surface layer inevitably causes frosted surfaces during casting, and casting accuracy is affected. If the adhesive is used for other layers, the bonding firmness between the layers is easily reduced, and delamination is caused. If the sand spraying height is too low, sand materials cannot penetrate into the inner layer of the ceramic shell, uneven state that the sand is covered on the surface layer to polymerize and the inside is lost can occur, so that the strength of the ceramic shell is uneven, and the sand-free inner surface part is easy to crack during drying, if the surface layer can cause puncture and flame running of the casting.
The invention improves the sand spraying treatment method, and the selection height of the preliminary sand spraying can penetrate into the ceramic shell to a certain depth instead of the strict limitation of the prior art. And then gradually lifting the sand spraying height, so that the later sand spraying has stronger impact force than the last sand spraying, and the sand spraying entering the ceramic shell before can be pushed by the sand spraying with stronger impact force after, and continuously infiltrates into the ceramic shell, so that the sand spraying operation is difficult to solve the problem of sand spraying penetration and uneven sand spraying distribution.
The invention provides a floating sand treatment method, which specifically comprises the following steps:
firstly, putting a ceramic shell to be dried into a floating sand machine, and starting the floating sand fan to enable sand materials in the floating sand machine to float and cover the surface of the ceramic shell to be dried.
And stopping the floating sand blower to enable sand materials in the floating sand blower to be static and stacked around the ceramic shell to be dried, and standing for a period of time.
Repeating the two steps until the floating sand treatment is completed.
The existing floating sand treatment method comprises the following steps: and placing the ceramic shell to be dried into a floating sand machine, and starting the floating sand fan to enable sand in the floating sand machine to float and cover the surface of the ceramic shell to be dried. However, the depth of sand entering the ceramic shell during floating sand treatment mainly depends on the power provided by a fan of a floating sand machine, and on one hand, the depth of floating sand entering the ceramic shell is difficult to control and is easy to be uneven due to the indirectly provided power. On the other hand, sand coating is hardly performed on leeward surfaces or in complex members (such as deep holes) where wind power is not easily available.
According to the invention, the method for treating floating sand is improved, after the floating sand treatment is finished, the floating sand blower is stopped, so that sand materials in the floating sand machine are static and stacked around the ceramic shell to be dried, and the floating sand machine is subjected to standing treatment for a period of time. At this time, under the action of sand fluidity, sand flows into the leeward surface of the component and the inside of the complex component, and is gradually pressed into the ceramic shell under the action of the standing pressure of the sand pile, so that sand is covered at the position where sand cannot be covered originally. The improved method mainly depends on the standing pressure of the sand pile, so that sand is easier to be pressed in at the ceramic shells with less sand, and is harder to be pressed in at the ceramic shells with more sand, and the uniformity of sand in each part in the final ceramic shells is balanced.
The invention provides a sand coating treatment mode, which specifically comprises the following steps: firstly, sand spraying treatment is carried out, and then floating sand treatment is carried out. The mode of sand spraying treatment adopts the sand spraying treatment method of the invention, and the mode of floating sand treatment adopts the floating sand treatment method of the invention.
Compared with the floating sand treatment, the sand coating uniformity is higher, for some complex components which are difficult to completely coat sand through the sand spraying treatment, such as construction of inner corner regions, the method can be adopted, the sand spraying treatment is firstly carried out, so that the sand coating treatment can be completed on the part which is difficult to be sprayed with sand, and then the floating sand treatment method is used for coating sand on the part which is difficult to be sprayed with sand.
The present invention illustratively provides a vacuum flash drying system, as shown in fig. 1, comprising: a vacuum drying chamber 1, a vacuum pump 8 and a control system. The vacuum pump 8 performs vacuum pumping treatment on the vacuum drying cavity 1. The vacuum pump 8 is communicated with the vacuum drying cavity 1 through a first connecting pipe, and a first electric control switch valve 10 is arranged on the first connecting pipe. The vacuum drying cavity 1 is communicated with an air pipe 106, and a second electric control valve 107 is arranged on the air pipe 106.
The drying frame 3 is detachably arranged in the vacuum drying cavity 1, and the ceramic shell 4 to be dried is detachably arranged on the drying frame 3 so as to be dried. At least two groups of wind turbine groups with different wind directions are arranged around the drying frame 3 in the vacuum drying cavity 1.
The control system includes: the vacuum drying control module and the fan set control module. The vacuum drying control module controls the opening and closing of the vacuum pump 8, the first electric control switch valve 10 and the second electric control valve 107, and the fan set control module controls the opening and closing and/or control parameters of all the fan sets.
In the vacuum drying system in the prior art, the fan set is generally installed in a constant-speed running mode, so as to realize the uniformity of drying, and the prior art is as the prior patent technology of the applicant: CN 201610416881.4 shows that by adopting two sets of different fan sets and a ceramic shell rotating device, the ceramic shell is enabled to continuously rotate and receive wind in the drying process, so as to improve the uniformity of the drying process. But this approach exists:
1. when the complex component with the deep hole is dried, the problem that the drying time of the deep hole is relatively uniform with that of other parts still cannot be overcome, namely when the complex component with the deep hole is dried, the phenomenon that the ceramic shell is overdried in the rest part of the ceramic shell can still occur when the drying of the ceramic shell with the deep hole is finished.
2. The ceramic shell has a certain centrifugal force in the rotating process, so that sand in the ceramic shell is easy to centrifugally deviate, and particularly when the viscosity of slurry is low.
3. The ceramic shell needs to be continuously rotated in the drying process, so that the ceramic shell to be dried has the possibility of relative sliding, and the ceramic shell is further collided or falls on the turntable, so that the ceramic shell is damaged.
By adopting the vacuum drying system, the fan set in the vacuum drying cavity 1 can be correspondingly controlled by the fan set control module, so that the drying windward degree of each part of the ceramic shell is changed by providing wind with different lateral directions and different strengths, the wind force of the windward side of the ceramic shell with the deep hole structure is stronger, the rapid volatilization of moisture in the deep hole is facilitated, the wind force of the windward side of the ceramic shell without the deep hole structure is weaker, the excessively rapid drying of the ceramic shell is avoided, and the drying time of each part of the ceramic shell tends to be consistent.
The present invention provides an exemplary fan set structure, specifically as shown in fig. 1 and 3: the inside of the vacuum drying cavity 1 is provided with a first blower unit 101 at the top of the drying frame 3, a second blower unit 102 is arranged at the bottom of the drying frame 3, a third blower unit 103 is arranged on the opening and closing door of the vacuum drying cavity 1 along the section direction of the drying frame 3 in the vacuum drying cavity 1, and a fourth blower unit 104 and a fifth blower unit 105 are respectively arranged at two sides of the drying frame 3 along the axial direction of the vacuum drying cavity 1.
The present invention illustratively provides an additional component, as shown in FIG. 1: the vacuum drying chamber 1 is internally provided with an adjustable member 108 on the opposite side of the third blower unit 103. The adjustable member 108 is: a condenser or a sixth blower unit.
The present invention illustratively provides a method of controlling a fan set, comprising: the vacuum drying chamber 1 is provided with a controller assembly. The controller component receives control signals and sends the control signals to the fan group control module so as to control the on-off and/or control parameters of each fan group.
The present invention illustratively provides a controller comprising: at least one of a knob controller, a key controller, a touch screen controller and a toggle switch.
The mode can adopt an off-line control mode to control the running state of the fan sets, namely, the controller selects whether each fan set is started or not and the operation is carried out according to the running ratio. The operating ratio is the ratio of the current fan rotation to the rated rotation.
The mode makes control system overall structure simple relatively, but needs operating personnel to observe the deep hole direction of the ceramic shell to be dried when drying the ceramic shell to control the operation ratio of corresponding fan of each group according to experience, and the drying effect is higher with the relativity of the observation ability of staff and working experience.
The present invention illustratively provides a manner of controlling a fan set, as shown in fig. 1-2, comprising: the vacuum drying cavity 1 is internally provided with a three-dimensional detection mechanism 2. The three-dimensional detection mechanism 2 drives the scanning device 207 to move along the X axis, the Y axis and the Z axis.
As shown in fig. 6, the scanning device 207 includes: an imaging device 2071. The camera 2071 is used for acquiring image data of the ceramic shell 4 to be dried.
The control system includes: and a ceramic shell analysis module. The ceramic shell analysis module acquires image data of the ceramic shell 4 to be dried and performs model structure analysis to obtain the position, the orientation and the depth of the deep hole of the ceramic shell 4 to be dried, and sends the deep hole to the fan set control module. And after the fan set control module performs fan set control analysis according to the deep hole position, the direction and the depth of the ceramic shell 4 to be dried, the on-off and/or control parameters of each fan set are controlled according to the analysis result.
The basic structure of the ceramic shell can be relatively and rapidly determined by adopting image data for analysis, and whether deep holes exist or not and the positions and the orientations of the deep holes are determined, so that a fan set facing the deep holes is determined, and the corresponding fan operation ratio control is performed.
The present invention exemplarily provides a three-dimensional detection mechanism, as shown in fig. 1 to 4, the three-dimensional detection mechanism 2 includes: two parallel X-axis guide rails 201 which are horizontally arranged along the axial direction of the vacuum drying cavity 1 and are respectively positioned at two sides of the drying frame 3, and Y-axis guide rails 202 which are horizontally arranged along the cutting direction of the vacuum drying cavity 1. The two X axial guide rails 201 are respectively provided with a first displacement device 203 capable of displacing along the X axial guide rail 201, and the Y axial guide rail 202 is fixed between the two first displacement devices 203 and is driven by the two first displacement devices 203 to displace along the X axial guide rail 201. The Y-axis guide 202 is provided with a second displacement device 204 that is displaceable along the Y-axis guide 202. The second displacement device 204 is provided with an electric control telescopic device 205 which stretches and contracts along the Z-axis direction along the vertical direction. The tail end of the telescopic end of the electric control telescopic device 205 is fixed with a scanning device 207 through an electric control cradle head 206. The first displacement device 203, the second displacement device 204, the electric control telescopic device 205 and the electric control cradle head 206 are respectively connected with a control system through signals.
The present invention illustratively provides a control system comprising: and a scanning device control module. The scanning device control module is used for controlling the movements of the two first displacement devices 203, the second displacement devices 204, the electric control telescopic devices 205 and the electric control cradle head 206, so that the scanning device 207 performs omnibearing shooting/scanning on the ceramic shell 4 to be dried to obtain image/scanning data of the ceramic shell 4 to be dried.
The scanning device control module can control the three-dimensional detection mechanism to drive the scanning device 207 to move in three dimensions of an X axis, a Y axis and a Z axis, so that the front, back, left, right and top 5 surfaces of the ceramic shell 4 to be dried are scanned in all directions, and the bottom is scanned in the lateral direction, so that a main structure image of the ceramic shell 4 to be dried is obtained, and the position and the orientation of a deep hole of the ceramic shell 4 to be dried can be determined more accurately.
The invention provides a model structure analysis method, which specifically comprises the following steps:
firstly, the outer contour model data, deep hole position data and deep hole depth data of the ceramic shell 4 to be dried are obtained.
And then, comparing the acquired image data with the outer contour model data, and determining the space orientation of the ceramic shell 4 to be dried in the vacuum drying cavity 1.
And finally, determining the current deep hole position and orientation of the ceramic shell 4 to be dried according to the space orientation of the ceramic shell 4 to be dried, and outputting the deep hole position and orientation of the ceramic shell 4 to be dried and depth data corresponding to the deep hole.
In recent years, the development of digital technology is rapid, the ceramic shell to be dried is designed in a digital modeling mode, and the ceramic shell to be dried obtained by the digital model design has detailed various structural data, so that the position and the orientation of a deep hole of the ceramic shell to be dried are rapidly determined through the image data of the ceramic shell to be dried by comparing the image data of the ceramic shell to be dried with the digital model, and the depth data corresponding to the deep hole of the ceramic shell to be dried can be obtained from the digital model.
The present invention illustratively provides a scanning device 207, as shown in fig. 6, the scanning device 207 further comprising: scanning distance measuring device 2073. The scanning distance measuring device 2073 is used for measuring the distance between the ceramic shell 4 to be dried and the scanning device 207 in real time.
The invention provides a model structure analysis method, which comprises the following steps:
step 1.1, the scanning distance measuring device 2073 performs omnibearing scanning on the surface n of the ceramic shell 4 to be dried according to a preset line to obtain a distance measuring data set Gn of all scanning points of the surface n relative to the scanning distance measuring device 2073.
And step 1.2, connecting the end points of the ranging data set Gn to obtain a digital surface m of the surface n of the ceramic shell 4 to be dried.
And 1.3, carrying out graphic analysis on the digital surface m of the ceramic shell 4 to be dried by combining the image data, and determining the basic surface, the convex surface and the concave surface of the digital surface m.
Step 1.4, calculating a difference Cmk-b of each ranging point in the groove surface relative to each ranging point of the adjacent basic surface of the groove, wherein mk is a groove with a number k on the digital surface m, and b is an additional number of the ranging point in the groove mk.
Step 1.5, cmk-b > K2 is taken as a deep hole, and Cmk-b > K3 is taken as a through hole. Wherein K2 is a preset deep hole judgment threshold value, and K3 is a model width or a model length or a model height corresponding to the surface n of the ceramic shell 4 to be dried.
And 1.6, counting the positions Wmc of all deep holes on the digital surface m of the ceramic shell 4 to be dried and the depth Hmc corresponding to each deep hole, wherein c is the natural number of the deep holes on the digital surface m.
Step 1.7 repeating the steps 1.1 to 1.6 until the positions Wmc and the depths Hmc of deep holes on the surface of the ceramic shell 4 to be dried, which can be scanned, are counted, and determining the orientation Xmc of the deep holes according to the surface n of the deep holes.
And step 1.8, outputting data of the positions Wmc, the depths Hmc and the orientations Xmc of deep holes on the whole surface of the ceramic shell 4 to be dried.
The invention provides an exemplary method for acquiring the basic surface, the convex surface and the concave surface in the step 1.3, which comprises the following steps:
and 1.3.1, acquiring image data corresponding to the digital surface m of the ceramic shell 4 to be dried, and splicing the image data to obtain an image surface R.
Step 1.3.2, element recognition is performed on the image plane R to obtain element regions rn-m on the image plane R, wherein rn is the sequence number of the element regions in the digital surface m.
Step 1.3.3 the digital surface m is adjusted to the same orientation and similar size as the image plane R.
Step 1.3.4 takes an element region rc-m with the largest continuous area as a basic surface, wherein the rc-m belongs to rn-m.
And 1.3.5, acquiring distance measurement point data of each non-basic surface element area, wherein element area distance measurement points with a distance greater than that of adjacent basic surface distance measurement points are groove points, and element area distance measurement points with a distance less than that of adjacent basic surface distance measurement points are raised points.
Step 1.3.6, using the element area as a boundary, connecting adjacent groove points and protruding points to form a groove surface and a protruding surface.
As shown in fig. 7, taking a left-hand front view plane with n=1 of six front view planes of a ceramic shell 4 to be dried as an example, the method specifically includes:
Step 1.1, the scanning distance measuring device 2073 performs omnibearing scanning on the surface n=1 of the ceramic shell 4 to be dried according to a preset line, and a distance measuring data set G1 of all scanning points of the surface n=1 relative to the scanning distance measuring device 2073 is obtained.
Step 1.2 as shown in fig. 8, the end points of the ranging data set G1 are connected to obtain a digital surface m=1 of n=1 on the surface of the ceramic shell 4 to be dried.
Step 1.3, carrying out graphic analysis on the digital surface m=1 of the ceramic shell 4 to be dried by combining the image data, and determining the basic surface, the convex surface and the concave surface of the digital surface m=1.
Step 1.4, calculating a difference Cmk-b of each ranging point in the groove surface relative to each ranging point of the adjacent basic surface of the groove, wherein mk is a groove with a number k on the digital surface m, and b is an additional number of the ranging point in the groove mk. Since there are two grooves k=1 and k=2 at the digital surface m=1, where the k=1 internal ranging points include 5 ranging points of b=8 to b=12, it is necessary to calculate Cmk-b=c11-8= | (L11-8) - (L11-13) |, cmk-b=c11-9= | (L11-9) - (L11-13) |, cmk-b=c11-10= | (L11-10) - (L11-13) |, cmk-b=c11-11= | (L11-11) - (L11-13) |, cmk-b=c11-12= | (L11-12) - (L11-13) | and Cmk-b=c11-12= |. The k=2 internal ranging points include 4 ranging points of b=18 to b=21, and thus it is necessary to calculate Cmk-b=c11-18= | (L11-18) - (L11-13) |, cmk-b=c11-19= | (L11-19) - (L11-13) |, cmk-b=c11-20= | (L11-20) - (L11-13) |, cmk-b=c11-21= | (L11-21) - (L11-13) |.
Step 1.5, cmk-b > K2 is taken as a deep hole, and Cmk-b > K3 is taken as a through hole. Wherein K2 is a preset deep hole judgment threshold value, and K3 is a model width or a model length or a model height corresponding to the surface n of the ceramic shell 4 to be dried. For example Cmk-b=c11-10 > K2, so the grooves of k=1 at the digital surface m=1 are deep holes.
Step 1.6, counting the positions Wmc =w11 of all deep holes on the digital surface m=1 of the ceramic shell 4 to be dried and the corresponding depth hmc=h11 of each deep hole, wherein c=1 is the natural number of the deep holes on the digital surface m=1. The position Wmc =w11 is the position corresponding to the ranging points 8 to 12, and the depth hmc=h11 corresponding to the deep hole is the calculated value of Cmk-b=c11-10.
Step 1.7 repeating the steps 1.1 to 1.6 until the positions Wmc and the depths Hmc of deep holes on the surface of the ceramic shell 4 to be dried, which can be scanned, are counted, and determining the orientation Xmc of the deep holes according to the surface n of the deep holes.
And step 1.8, outputting data of the positions Wmc, the depths Hmc and the orientations Xmc of deep holes on the whole surface of the ceramic shell 4 to be dried.
The invention provides an exemplary method for acquiring the basic surface, the convex surface and the concave surface in the step 1.3, which comprises the following steps:
and 1.3.1, acquiring image data corresponding to the digital surface m of the ceramic shell 4 to be dried, and splicing the image data to obtain an image surface R.
Step 1.3.2, element recognition is performed on the image plane R to obtain element regions rn-m on the image plane R, wherein rn is the sequence number of the element regions in the digital surface m.
Step 1.3.3 the digital surface m is adjusted to the same orientation and similar size as the image plane R.
Step 1.3.4 takes an element region rc-m with the largest continuous area as a basic surface, wherein the rc-m belongs to rn-m.
And 1.3.5, acquiring distance measurement point data of each non-basic surface element area, wherein element area distance measurement points with a distance greater than that of adjacent basic surface distance measurement points are groove points, and element area distance measurement points with a distance less than that of adjacent basic surface distance measurement points are raised points.
Step 1.3.6, using the element area as a boundary, connecting adjacent groove points and protruding points to form a groove surface and a protruding surface.
In the prior art, not all ceramic shells 4 to be dried are obtained by adopting a digital model design mode, or the digital model of the ceramic shells 4 to be dried obtained by adopting the digital model design mode and a vacuum quick drying system are not mutually supported, at the moment, the vacuum quick drying system cannot determine whether shadows in image data are deep holes or not by using the digital model, and cannot determine the depth of the deep holes by using the image data. By adopting the method, the data of the positions Wmc, the depths Hmc and the orientations Xmc of the deep holes on the whole surface of the ceramic shell 4 to be dried can be confirmed by an automatic scanning and analyzing method through an automatic analyzing method. So that the vacuum quick drying system can acquire the data of the position Wmc, the depth Hmc and the orientation Xmc of the deep holes on the whole surface of the ceramic shell 4 to be dried necessary for the control analysis of the fan set.
The present invention illustratively provides an electrically controlled pan-tilt 206, as shown in fig. 5, comprising: a stationary table 2061 fixed to the electrically controlled telescoping device 205, and a rotating table 2062 rotatably connected to the stationary table 2061 and rotatable about a vertical axis relative to the stationary table 2061. The rotating table 2062 is rotatably connected with the fixed end of the second electric control telescoping device 2064 through a speed reducer 2063, and the speed reducer 2063 controls the second electric control telescoping device 2064 to rotate along the horizontal shaft. The telescoping end of the second electrically controlled telescoping device 2064 holds the scanning device 207.
The conventional cradle head is difficult to realize the scanning of the bottom of the ceramic shell 4 to be dried, so that the cradle head structure is improved, the scanning device 207 can scan the bottom of the ceramic shell 4 to be dried through the second electric control telescopic device 2064, and the rotation direction of the scanning device 207 can be changed through the speed reducer 2063, so that the degree of freedom of one scanning movement is increased, and the scanning device 207 can adapt to the more complex ceramic shell 4 to be dried.
The invention provides a model structure analysis method, which is based on the model structure analysis, and further comprises the following steps:
and 2.1, controlling the scanning distance measuring device 2073 to move to the deep hole position according to the deep hole position.
Step 2.2, obtaining a plurality of deep hole depth measurement data by adjusting the orientation of the relative deep holes of the scanning distance measuring device 2073.
And 2.3, correcting the depth data Hm-c of the original deep hole by using the depth measurement data with the deepest depth to obtain corrected data Hm-c'.
When the ceramic shell 4 to be dried is designed, the deep hole structure is generally designed on the axis of the model, so that the deep holes of the ceramic shell are distributed along the axis, and in the scanning ranging process, the ranging laser can be enabled to penetrate into the deep holes, the ranging data of the deep holes are obtained through measurement, and the depth of the deep holes can be obtained. However, in actual work, not all the deep holes of the ceramic shells are designed along the axis, and not all the ceramic shells 4 to be dried are placed or hooked in the forward direction when being dried, so that the deep holes deflect towards the operation axis of the relative scanning device 207, at the moment, the laser emitted by the scanning distance measuring device 2073 cannot penetrate into the deep holes, and the measured depth of the deep holes is subject to errors, so that the accuracy of control analysis of a fan unit is affected, the actual drying speed and the designed drying speed of the deep holes of the ceramic shells 4 to be dried are greatly different, and the drying uniformity of all the ceramic shells 4 to be dried is affected.
By adopting the complementary model structure analysis method, the orientation of the scanning distance measuring device 2073 relative to the deep hole can be adjusted at the position of the deep hole, so that the scanning distance measuring device 2073 can obtain a plurality of distance measuring data of different orientations of the relative deep hole, wherein the distance measuring data comprises distance measuring point distance measuring data of which the orientation of the scanning distance measuring device 2073 is consistent with or similar to the axis of the deep hole, and the distance measuring data is consistent with or similar to the depth of the deep hole, so that the accuracy of fan set control analysis can be remarkably improved, and the difference between the actual drying speed and the designed drying speed of the deep hole part of the ceramic shell 4 to be dried is remarkably reduced.
The present invention exemplarily provides a scanning device 207, as shown in fig. 6, further including, on the basis of the scanning device 207: an infrared temperature measurement device 2074. The control system includes: and the drying process analysis module is used for acquiring the measured quantity of the infrared temperature measuring device 2074 to carry out drying process analysis so as to judge whether the ceramic shell 4 to be dried is dried.
The invention provides a drying process analysis method, which comprises the following steps: the temperature T inside the borehole is measured periodically or continuously. And (3) making a curve Qv of the deep hole temperature Tv-the drying time t, and when all the Qv have curve sections conforming to a preset curve rule, indicating that the ceramic shell 4 to be dried is completely dried. Wherein v is the natural number of all deep holes of the ceramic shell 4 to be dried.
The present invention provides a preset curve rule, as shown in fig. 9, including: the temperature T in the deep hole gradually decreases to a temperature T2 along with the drying time from the initial drying temperature T1, then gradually increases to the ambient drying temperature T3 along with the drying time, and when the temperature T of the deep hole of the ceramic shell 4 to be dried is subjected to T1-T2-T3 and the ambient drying temperature T3 is maintained for a preset time U, the completion of drying is judged. The initial drying temperature T1 is 22-26 ℃, the temperature T2 is 5-7 ℃ lower than the temperature T1, and the ambient drying temperature T3 is 24+/-1 ℃.
The prior art mainly relies on experience or tests to obtain corresponding drying time under certain drying conditions in a manner of judging that the ceramic shell 4 to be dried is dried, and when the drying time is reached, the ceramic shell is judged to be dried. However, when the method is used for the ceramic shells 4 to be dried with multiple batches, the drying time needs to be adjusted correspondingly due to inconsistent structures of the ceramic shells 4 to be dried in each batch, so that the drying time test needs to be performed in advance, and the overall drying efficiency is seriously affected.
The applicant has studied that in the drying process of the ceramic shell 4 to be dried, the evaporation of moisture is an endothermic process, and in the initial drying stage, because the moisture content in the ceramic shell slurry is high, a large amount of moisture is evaporated in the initial drying stage of the ceramic shell, so that the temperature of the ceramic shell can be remarkably reduced. When the moisture volatilizes to a certain extent, the moisture content in the ceramic shell slurry is reduced, so that the moisture volatilization speed is reduced, and the temperature of the ceramic shell gradually tends to the drying environment temperature. When the temperature of the ceramic shell was maintained at the drying ambient temperature, it indicated that little moisture had evaporated, also representing the completion of drying. Therefore, the method for judging the completion of drying the ceramic shell 4 to be dried is adopted to judge whether the drying of the ceramic shell 4 to be dried is completed or not, and is only related to the temperature change curve of the drying process, but not related to the structure of the ceramic shell 4 to be dried, so that the ceramic shell 4 to be dried can be accurately dried for each batch, and the problems of the existing drying time control method are effectively solved.
Meanwhile, the applicant has studied: the ceramic shell slurry can reduce the temperature along with the volatilization of the moisture in the drying process, and the volatilization of the moisture can lead to certain shrinkage of the ceramic shell (even if sand is supported). At this time, in the initial stage of drying the ceramic shell, the wax mould is also cooled and contracted due to the influence of the cooling of the ceramic shell, so that the ceramic shell is adhered to the surface of the contracted wax mould in the drying process. When the ceramic shell starts to return to temperature, the wax mould also expands along with the temperature rise, however, the shrinkage and expansion process of the wax mould under the influence of the temperature is slower than the change of the ceramic shell, so that:
if the cooling time of the ceramic shell is too long, namely the cooling amplitude is smaller, the drying time is too long, the wax mould can be completely contracted under the action of a longer low temperature, on one hand, the ceramic shell can be attached to the wax mould which is obviously contracted, and therefore the space deformation of a finally obtained ceramic shell is obvious, and the casting precision is influenced. On the other hand, when the wax mould is expanded at the temperature, the ceramic shell solidified and coated on the surface of the contracted wax mould is easily broken due to the overlarge recovery-expansion ratio, so that the ceramic shell is failed to prepare or irregular spurs appear on the surface of the casting, and the casting precision is influenced. And too long drying time also affects the ceramic shell preparation efficiency.
If the cooling time of the ceramic shell is too short, namely the cooling amplitude is too large, the drying time is too short, the problem that the deep hole is not dried yet and the surface is dried often occurs, namely the window period for adjusting the drying time is very short, which is not beneficial to adjusting the drying time of each part of the ceramic shell 4 to be dried, and the control difficulty of the drying uniformity of the ceramic shell 4 to be dried is increased.
The slurry density of the ceramic shell is lower, the water content is higher, so that the slurry which can be hung when the slurry is hung is less, the thickness of each ceramic shell layer is smaller, the thermal conductivity is better, various adverse problems caused by overlong or too short cooling time of the ceramic shell are easy to occur in the slurry ceramic shell, the control precision requirement of the drying process is too high, and the realization difficulty is higher.
Compared with the thin ceramic shell, the thick ceramic shell has higher concentration of ceramic shell slurry and lower moisture content, so that more slurry can be hung when the ceramic shell is hung, and each layer of ceramic shell has larger thickness and poorer heat conductivity. Under the condition that the temperature of T2 is 5-7 ℃ lower than the temperature of T1: the ceramic shell can be enabled to have a proper drying speed, on one hand, the ceramic shell can be efficiently dried, and meanwhile, the fact that all parts of the ceramic shell are dried too fast to be easy to adjust the drying progress is avoided. On the other hand, the wax mould can be dried when the wax mould is not fully contracted, and then the wax mould and the ceramic shell are both warmed to the room temperature, so that the problem of cracking the ceramic shell by the wax mould can be avoided.
The invention provides a drying completion judging method for a plurality of ceramic shells 4 to be dried, which comprises the following steps: detecting the temperature of each deep hole of each ceramic shell 4 to be dried one by one, and judging that the drying of the ceramic shells 4 to be dried is finished in the whole batch when more than L% of the ceramic shells 4 to be dried are dried. The ratio of L% = (Lg-d)/(L0-d) is 100%, where Lg-d is the number of dried ceramic shells 4 in the batch d, and L0-d is the number of all ceramic shells 4 in the batch d. Wherein the value of L% is as follows: 100 percent or more, L percent or more, E percent or more. Wherein E is a preset threshold for the minimum drying completion percentage of all ceramic shells 4 to be dried for batch d.
In order to improve the drying efficiency of the ceramic shells, a plurality of ceramic shells 4 to be dried with the same structure are always dried synchronously in a batch of drying process, the ceramic shells are limited to different placement or hooking modes of a plurality of ceramic shells 4 to be dried, and the air-receiving degree of each ceramic shell 4 to be dried is different, and the drying time is different, so that a certain margin control is needed, and the vacuum quick drying is stopped after the drying of most ceramic shells 4 to be dried is finished, so that the problem of excessive drying of most ceramic shells 4 to be dried after the drying of the ceramic shells with less air-receiving is avoided. The preset percentage threshold is determined according to the wind difference condition of the ceramic shells 4 to be dried, and the value is generally not lower than 98%. Thus, after the drying is finished, even if the ceramic shell 4 to be dried which is not completely dried exists, the moisture content of the ceramic shell is not too high, and the ceramic shell can be continuously dried in the subsequent drying process so as to realize the drying completion.
The invention provides a fan set control analysis method A, which comprises the following steps:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells 4 to be dried, the following method is adopted:
and 3.1, obtaining the total number D0 of all deep holes of the ceramic shell 4 to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell 4 to be dried of the facing fan group p. And p is the number of the fan set arranged on different sides in the vacuum drying cavity 1.
Step 3.2 calculates kS-p% = Dp/D0 x 100%, where kS-p% is the control parameter of fan set p.
Step 3.3 steps 3.1 to 3.2 are repeated until the kS-p% of the total set of fans is obtained.
For all the fan groups p facing the surface of the ceramic shell 4 to be dried without deep holes, the following method is adopted:
calculating kF-p% = [ 1-D0/(D0+1) ], wherein kF-p% is a control parameter of the fan group p.
The fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
For example: total number of deep holes d0=4 of ceramic shell 4 to be dried, total number of deep holes d1=1 of surface of ceramic shell 4 to be dried of facing fan group p=1, total number of deep holes d2=1 of surface of ceramic shell 4 to be dried of facing fan group p=2, total number of deep holes d3=2 of surface of ceramic shell 4 to be dried of facing fan group p=3, and the rest of ceramic shell 4 to be dried has no deep holes and is provided with corresponding fan group p=4, fan group p=5, fan group p=6.
At this time, the calculation results in:
kS-1％＝D1/D0*100％＝(1/4)*100％＝25％。
kS-2％＝D2/D0*100％＝(1/4)*100％＝25％。
kS-3％＝D3/D0*100％＝(2/4)*100％＝50％。
kF-4％＝kF-5％＝kF-6％＝[1-D0/(D0+1)]*100％＝(1-4/5)*100％＝20％。
by adopting the fan set control analysis method provided by the invention, the running conditions of each set of fan sets can be automatically and adaptively adjusted according to the obtained deep hole distribution condition of the ceramic shell 4 to be dried, so that the part with more deep holes of the ceramic shell 4 to be dried is improved in wind stroke degree, the drying speed is higher, and the quick drying in the deep holes is facilitated. And the part with few or no deep holes is correspondingly reduced in wind stroke, so that the drying speed is slowed down, and the drying time synchronization with the deep hole part is facilitated. Thereby realizing that the drying is finished in a shorter drying time on the basis of ensuring that the drying degree of each part of the ceramic shell 4 to be dried tends to be consistent.
And the method is only related to the quantity and the position of deep holes of the ceramic shell 4 to be dried, and can realize better drying control of shorter drying time and uniform drying time of each part of the ceramic shell aiming at various structures, such as the ceramic shell 4 to be dried with standard or non-standard structures.
The invention provides a fan set control analysis method B, which comprises the following steps:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells 4 to be dried, the following method is adopted:
and 4.1, obtaining the total number D0 of all deep holes of the ceramic shell 4 to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell 4 to be dried of the facing fan group p. And P is the serial number of the fan set arranged on different sides in the vacuum drying cavity 1.
And 4.2, obtaining kS-p% from a control parameter database according to the numbers of D0 and Dp. The kS-p% is a control parameter of the fan group p.
Step 4.3 steps 4.1 to 4.2 are repeated to obtain kS-p% of the total fan set.
For all the fan groups p facing the surface of the ceramic shell 4 to be dried without deep holes, the following method is adopted:
and obtaining kF-p% from a control parameter database according to the total number D0 of all deep holes of the ceramic shell 4 to be dried. The kF-p% is a control parameter of the fan group p.
The fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
The invention provides an example of recording k in a control parameter database S-p % and kF-p% method comprising:
step 5.1 simulates the same fan set position and orientation as the target vacuum drying chamber 1 in the simulation device.
Step 5.2, presetting deep hole distribution conditions of different ceramic shells 4 to be dried for drying training, and determining control parameters k of each fan set p corresponding to optimal drying time under each deep hole distribution condition when the fan set p is relatively fully loaded S-p % and kF-p%; the deep hole distribution condition comprises: deep hole orientation and number; the optimal drying time is the shortest time for synchronously drying deep holes and surface layers of each surface of the ceramic shell 4 to be dried;
Step 5.3 repeating the step 5.2 until training of deep hole distribution under normal conditions is completed, and constructing D0-Dp-k S-p And (3) a deep hole-control parameter relation group of%kF-p% and storing the deep hole-control parameter relation group into a control parameter database.
By adopting the fan set control analysis method provided by the invention, a massive deep hole-control parameter relation set under the optimal condition with comprehensive related conditions can be prepared in a database of a vacuum drying system in a pre-experiment mode. Thus, when the total number D0 of the deep holes of the ceramic shell 4 to be dried is obtained, the total number Dp of the deep holes of the surface of the ceramic shell 4 to be dried of the facing fan group p is obtained, the optimal k theoretically related to D0-Dp can be obtained according to the deep hole-control parameter relation group pre-stored in the control parameter database in advance S-p % and kF-p% control the corresponding fan set.
The best results from the experiments are shown as follows: under the specific deep hole relation group of D0-Dp, k is used S-p The control parameters of the% -kF-p% control the operation of the fan set, so that the shortest drying time can be achieved on the basis of ensuring that the drying degree of each part of the ceramic shell 4 to be dried tends to be consistent. The drying time is closely related to the volume, surface area and surface structure of the ceramic shell 4 to be dried, so that the method needs to be matched with the digital model structure of the ceramic shell 4 to be dried for judgment. The standard ceramic shell 4 to be dried belongs to a common component, can be subjected to experimental simulation in advance, and the nonstandard ceramic shell 4 to be dried is a special-shaped piece designed according to the requirement, so that the structural mode is various, the prior experiment can not be covered, and the D0-Dp-k corresponding to the special-shaped ceramic shell 4 to be dried is lacking in a control parameter database S-p When the deep hole-control parameter relation group of%to kF-p% is formed, the fan set control analysis method B cannot obtain the required D0-Dp-k S-p The deep hole-control parameter relation group of% -kF-p% is analyzed by adopting a fan set control analysis method A provided by an example to obtain D0-Dp-k corresponding to the special-shaped ceramic shell 4 to be dried S-p Deep hole-control parameter relation set of% -kF-p%.
The fan set control analysis method B and the fan set control analysis method A can be used independently and respectively, or can be used in combination.
The invention provides a fan set, wherein at least two fans are arranged in the fan set. And the fan group control module synchronously controls or independently controls the fans in each group of fan groups.
The invention provides a fan set control analysis method C based on at least two fans in a fan set, which further comprises the following steps of:
step 6.1 constructs a three-dimensional coordinate system based on a scanning start point preset by the scanning device 207.
And 6.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device 207, and marking the three-dimensional coordinate point on the position, the orientation and the depth of the deep hole of the ceramic shell 4 to be dried in the model structure analysis process.
And 6.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fans in the fan set p.
And 6.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area.
Step 6.5 calculates kup-e% = (Dup-e/Dup) ×ks-p%.
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load. For the fan corresponding to Dup-e=0, it is operated at the lowest power.
For example: the fan set p contains two fans, numbered p-1 and p-2, and since the fans are fixed relative to the preset scanning start point of the scanning device 207, the coordinate positions of the fans p-1 and p-2 in the three-dimensional coordinate system constructed in step 6.1 are also fixed. At this time, the fan p-1 can form a cylindrical air duct p-1 with the axis of the fan rotating shaft as a central axis and the diameter r=100 cm in a three-dimensional coordinate system, and the intersection surface of the cylindrical air duct p-1 and the corresponding surface of the ceramic shell 4 to be dried is the coordinate system range Up-1 covered by the fan p-1. The number Dup-1 of deep holes present in Up-1, e.g., dup-1=1, dup-2=2, and the number Dup of deep holes in the entire coverage of the fan group p, e.g., dup=3, are counted. From this it can be calculated:
kup-1％＝(Dup-1/Dup)*kS-p％＝(1/3)*kS-p％。
kup-2％＝(Dup-2/Dup)*kS-p％＝(2/3)*kS-p％。
That is, in the fan group p, the fan 1 is operated in a state of (1/3) ×ks-p%, and the fan 2 is operated in a state of (2/3) ×ks-p%.
By adopting the fan set control analysis method C, the independent control parameters of each fan in the fan set p can be obtained in a calculation mode, so that corresponding independent control of a plurality of fans in the fan set p is realized. The method can enable the wind blown by the fan set p to the ceramic shell 4 to be dried to be more specific, and enable the drying completion time of all parts of the ceramic shell 4 to be dried, especially the deep hole distribution area non-deep hole distribution area, to be more consistent.
The invention provides a fan set control analysis method D based on at least two fans in a fan set, which further comprises the following steps on the basis of the fan set control analysis method A or the fan set control analysis method B:
step 7.1 constructs a three-dimensional coordinate system based on a scanning start point preset by the scanning device 207.
And 7.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device 207, and marking the three-dimensional coordinate point on the position, the orientation and the depth of the deep hole of the ceramic shell 4 to be dried in the model structure analysis process.
And 7.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fans in the fan set p.
And 7.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area.
Step 7.5, acquiring kup-e% of corresponding fans from a control parameter database according to Dup and Dup-e, wherein kup-e% are control parameters of fans with numbers e in the fan group p.
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load.
The invention provides a method for recording kup-e% into a control parameter database, which comprises the following steps:
step 8.1 simulates the same fan set position and orientation as the target vacuum drying chamber 1 in a simulation device.
And 8.2, presetting deep hole distribution conditions of different ceramic shells 4 to be dried for drying training, and determining the running proportion kup-e% of each fan in each fan group p corresponding to the optimal drying time under each deep hole distribution condition when the fans are fully loaded. The deep hole distribution condition comprises: deep hole orientation and number. The optimal drying time is the shortest time for the deep holes and the surface layers of each surface of the ceramic shell 4 to be dried synchronously.
And 8.3, repeating the step 8.2 to the conventional deep hole distribution condition training, constructing a deep hole-control parameter relation group of Dup-e-kup-e%, and storing the deep hole-control parameter relation group in a control parameter database.
By adopting the fan set control analysis method provided by the invention, a massive deep hole-control parameter relation set of Dup-e-kup-e% under the optimal condition of relatively comprehensive related conditions can be prepared in a database of a vacuum drying system in a pre-experiment mode. Thus, when determining the number Dup-e of deep holes in the coordinate system ranges Up-e and Up-e coverage of each fan blowing direction in the fan set p and the number Dup of deep holes in the whole coverage of the fan set p, the corresponding fan control parameters can be independently controlled according to the deep hole-control parameter relation group of Dup-e-kup-e% pre-stored in advance in the control parameter database by the optimal kup-e% related to Dup-e theoretically.
The same as the example fan set control analysis method B, the example fan set control analysis method D is mainly applicable to the ceramic shells 4 to be dried with the model structure covered by the pre-simulation experiment, and for the ceramic shells 4 to be dried with the model structure not covered by the pre-simulation experiment, the deep hole-control parameter relation set of Dup-e-kup-e% is obtained by the example fan set control analysis method C.
The present invention illustratively provides a vacuum flash drying system comprising: the system comprises a first data transmission module, a local database module and a remote system module.
The first data transmission module is connected with the remote system module through a signal line or a wireless network.
The local database module is used as a control parameter database for storing related deep hole-control parameter relation groups and operation result data.
And the remote system module collects deep hole-control parameter relation groups and operation result data of each vacuum quick drying system through the first data transmission module, and selects a deep hole-control parameter relation group corresponding to the optimal operation result from the same deep hole relation. And based on authorization permission and/or instructions and/or an automatic synchronization mode, the deep hole-control parameter relation group corresponding to the optimal operation result is concentrated through a remote system and then is synchronized into the local database module of each vacuum quick drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum quick drying system through the first data transmission module.
When the vacuum quick drying system calls the deep hole-control parameter relation group in the local database module, if a new optimal deep hole-control parameter relation group exists, the new optimal deep hole-control parameter relation group is preferentially called.
For example: the vacuum quick drying systems are networked with the remote system through the Internet, and the best result corresponding to the Dup-e-kup-e% deep hole-control parameter relation set recorded by the local database module of each vacuum quick drying system aiming at the model A is B; at this time, it has been found by experiment or by accident that a certain enterprise or equipment manufacturer can obtain a better result C than the best result B by adjusting the control parameters in the Dup-e-kup-e% deep hole-control parameter relation group to kup-e'. At this time, the new Dup-e-kup-e%' deep hole-control parameter relation set recorded for the model a and the corresponding optimal result are that C is collected in a centralized manner by the remote system of the present invention, and then synchronized to the local database module of each vacuum flash drying system by the first data transmission module, or directly synchronized to the local database module of each vacuum flash drying system by the first data transmission module.
By the data synchronization method, the optimal control parameters for a certain model obtained by a certain enterprise or equipment manufacturer can be synchronized to all other networked vacuum quick drying systems, so that the control parameter optimization degree of the model under the Dup-e condition is improved, and the drying efficiency is improved. Therefore, the invention can continuously optimize and perfect the control parameters of the fan unit and each fan in the fan unit in the actual operation process, improve the integral drying efficiency and improve the benefit of enterprises.
The present invention illustratively provides a vacuum flash drying system comprising: a second data transmission module and a remote system.
The remote system is connected with a control system signal of the vacuum quick drying system through a second data transmission module in a signal line connection or wireless network connection mode, so as to send remote control instructions to the control system and/or acquire control instructions sent by the control system and/or acquire operation state parameters of various electric control devices in the vacuum quick drying system.
The execution priority of the remote control instruction sent by the remote system is higher than the execution priority of the control instruction sent by the control system.
The vacuum quick drying system of this example can be operated with the intervention of a remote system to achieve remote control of the vacuum quick drying system. The method is exemplary, can facilitate remote regulation and control of equipment and self-checking of equipment for users by suppliers, and improves the efficiency of early equipment adjustment and later equipment maintenance.
The present invention illustratively provides a drying rack 3 comprising: and a ceramic shell hanging frame 304 for hanging the ceramic shell 4 to be dried. The ceramic shell hanging rack 304 is provided with a plurality of hanging grooves 305. The ceramic shell 4 to be dried is hooked at the hooking groove 305 through the hook 11. The bottom of the ceramic shell hanging frame 304 is fixedly provided with a hanging frame supporting plate 302. The bottom of the hanger bracket 302 is provided with a plurality of rollers 303 which can slide along the guide rail 301. The guide rail 301 is fixed to the bottom surface of the inside of the vacuum drying chamber 1.
Because the ceramic shell preparation process involves multiple sizing and corresponding drying operations, a convenient detachable fixing mode is needed between the ceramic shell 4 to be dried and the ceramic shell hanging frame 304 and the vacuum drying cavity 1. The invention provides a detachable fixing mode between a ceramic shell 4 to be dried, a ceramic shell hanging frame 304 and a vacuum drying cavity 1, which comprises the following specific steps: the ceramic shell 4 to be dried can be hooked at the hooking groove 305 through the hanging hook 11, so that hooking/taking-down of the ceramic shell 4 to be dried and the ceramic shell hanging frame 304 can be conveniently and detachably fixed. And then the ceramic shell hanging frame 304 slides into/out of the guide rail 301, so that convenient and detachable fixation between the ceramic shell 4 to be dried and the vacuum drying cavity 1 is realized.
The invention provides a guide rail 301, and a limiting block is arranged on one side of the guide rail 301 away from a door of a vacuum drying cavity 1. As shown in fig. 1, the guide rail 301 is provided with a stopper on a side close to the adjustable member 108. The arrangement can enable the sliding position of the ceramic shell hanging frame 304 in the vacuum drying cavity 1 to be relatively fixed, so that the quantity of ceramic shells 4 to be dried, which are faced by a fan unit in each drying process, is similar, and the drying stability is improved.
The present invention illustratively provides a scanning apparatus 207, the scanning apparatus 207 comprising: thermal imager 2072. The method for enabling the drying time of all parts of the whole ceramic shell to be dried to be consistent comprises the following steps:
Step 9.1, performing real-time thermal imaging shooting on the ceramic shell 4 to be dried along with the scanning device 207 by the thermal imager 2072 in the drying process of the ceramic shell 4 to be dried, and sending the shooting to a control system.
And 9.2, the control system judges whether an area T with the temperature difference exceeding a preset temperature difference threshold exists according to the thermal imaging graph when the drying time exceeds the preset first drying time according to the heat distribution condition in the thermal imaging graph, and if the area T exists, the control system judges and operates as follows:
and when the temperature of the low-temperature area of the area T is lower than a preset low-temperature threshold value, reducing the operation power of the fan set corresponding to the area T.
And when the temperature of the high-temperature area of the area T is higher than a preset high-temperature threshold value, increasing the operating power of the area T corresponding to the fan set.
When the existence time of the area T exceeds a preset time threshold, the temperature of a low-temperature area of the area T is higher than a preset low-temperature threshold, and the temperature of a high-temperature area of the area T is lower than a preset high-temperature threshold, the operation power of the area T corresponding to the fan set is increased.
The invention provides a preset low-temperature threshold value, which is as follows: 12-15 ℃.
The invention provides a preset high temperature threshold value, which is as follows: 26-28 ℃.
The invention provides a method for presetting a first drying time, which comprises the following steps: 1-3 minutes.
The invention provides a preset time threshold value, which is as follows: 30-60 seconds.
It is one of the main problems to be solved by the present invention to make the drying degree of each part of the ceramic shell 4 to be dried tend to be uniform and the drying time of each part of the ceramic shell 4 to be dried tend to be uniform. By adopting the method for enabling the drying time of all parts of the ceramic shell to be dried to be consistent, the control parameters of all the fan sets can be dynamically regulated and controlled based on the temperature change of all the parts in the whole thermal imaging diagram of the ceramic shell to be dried 4 in the drying process, so that the drying time of all the parts in the drying process of the ceramic shell to be dried 4 is more consistent.
The invention provides a method for vacuum quick drying treatment, which comprises the following steps:
drying the surface layer: firstly, the vacuum degree of the environment of the ceramic shell to be dried is reduced to 750-720 mmHg from normal pressure within 5 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 5 seconds from 750 to 720 mmHg. And (5) circulating the process until the surface layer is dried.
When the transition layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 720-680 mmHg within 7 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 7 seconds from 720 to 680 mmHg. And (5) repeating the above process circularly until the transition layer is dried.
When drying the support layer, the method comprises the following steps:
step 10.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-20 mmHg within 30 seconds.
And 10.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 10.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 10.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-20 mmHg within 30 seconds.
Step 10.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 10.6 repeat steps 10.4 and 10.5 until the support layer is dried.
When the sealing layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 120-90 mmHg within 40 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 120 seconds. And (5) repeating the process circularly until the sealing layer is dried.
The existing vacuum rapid drying technology for ceramic shells mainly enables a surface layer and a transition layer to be rapidly dried through the reciprocating operation of vacuumizing and re-pressing on the basis of a thin ceramic shell, and a supporting layer can be expanded to form a spongy structure body under the reciprocating high negative pressure condition, so that the breaking strength coefficient of the ceramic shell is reduced while the thickness of the ceramic shell is increased.
Compared with the existing vacuum rapid drying technology for the thin pulp ceramic shell, the thick pulp ceramic shell can realize rapid drying under simpler control conditions theoretically due to lower water content, for example: vacuum flash drying method for thin ceramic shells disclosed in CN 201610416881.4: when the support layer of the ceramic shell is dried, the sealed cavity is pumped into a vacuum state of 300-100 mm mercury column within 60 seconds, the vacuum state is maintained for 400-600 seconds, and then the sealed cavity is subjected to vacuum deflation, so that the sealed cavity is changed into a normal pressure state; then starting a step b, wherein the sealed cavity is pumped into a vacuum state of 300-100 mm mercury column within 60 seconds in the step b, and then performing a step c; c, vacuum deflating the sealed cavity within 120 seconds to enable the sealed cavity to be changed back to a normal pressure state, and then restarting the step b; the support layer of the prepared ceramic shell is in a spongy loose structure. "according to common general knowledge, when drying the support layer of the thick slurry ceramic shell, rapid drying can be achieved under simpler control conditions, for example: the pressure is reduced within a slower time range of 90 seconds, and the sealed cavity is pumped into a vacuum state of 500-400 mm mercury column, so that quick drying can be realized. However, in fact, in order to obtain a better dried dense slurry ceramic shell, the vacuum drying condition is more difficult than that of a thin slurry ceramic shell, for example, when the support layer of the dense slurry ceramic shell is dried, the vacuum degree of the environment of the ceramic shell to be dried needs to be reduced from the normal pressure to 260-20 mmHg within 30 seconds, and the environment needs to be restored to the normal pressure within 90 seconds. This is because the content of moisture in the thick-slurry ceramic shell is low, and the content of sand or particulate material is relatively high, and the flow of moisture and air flow in the thick-slurry ceramic shell is easily blocked, which results in the problem that the surface of the ceramic shell is easily dried and the moisture in the ceramic shell is not evaporated yet in the drying process. Therefore, in a lower control environment in theory, the difference between the evaporation efficiency of the water in the thick slurry ceramic shell and the theoretical efficiency is larger, and the water and bubbles in the thick slurry ceramic shell can form effective flow at a higher depressurization speed in a lower negative pressure environment, so that on one hand, a uniformly distributed spongy structure body caused by the flow of the bubbles can be formed in the thick slurry ceramic shell in the drying process, and the expansion of the thickness of the ceramic shell layer is formed, and on the other hand, the water in the thick slurry ceramic shell can be effectively discharged, so that the quick drying can be truly realized.
The invention provides a drying method of a supporting layer, which sequentially comprises at least three layers from a transition layer to a sealing layer, wherein:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 11.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
And 11.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes.
Step 11.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
Step 11.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.6 repeating steps 11.4 and 11.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 12.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
And 12.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 12.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
Step 12.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.6 repeating steps 12.4 and 12.5 until the second layer of the support layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 13.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
And 13.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 13.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
Step 13.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.6 repeating steps 13.4 and 13.5 until the third layer of the support layer is dried.
And the inner surface of the closed layer is attached to the outer surface of the third layer of the supporting layer.
The vacuum rapid drying method can enable the thick slurry ceramic shell supporting layer to have better drying speed in the vacuum drying process, and enable the ceramic shell obtained by drying to have good breaking strength coefficient and provide enough supporting force to meet the use requirement of precision casting.
The present invention illustratively provides a vacuum flash drying system, as shown in fig. 1, comprising: a vacuum drying chamber 1, a vacuum pump 8 and a control system. The vacuum pump 8 performs vacuum pumping treatment on the vacuum drying cavity 1. The vacuum pump 8 is communicated with the vacuum drying cavity 1 through a first connecting pipe, and a first electric control switch valve 10 is arranged on the first connecting pipe. The vacuum drying cavity 1 is communicated with an air pipe 106, and a second electric control valve 107 is arranged on the air pipe 106.
And the ceramic shell 4 to be dried is placed into a vacuum drying cavity 1 for vacuum rapid drying treatment.
The control system controls the opening and closing of the vacuum pump 8, the first electric control switch valve 10 and the second electric control valve 107 to realize the method steps of the vacuum quick drying treatment.
The vacuum flash drying system further comprises: a vacuum tank 5. One end of the vacuum tank 5 is communicated with the vacuum pump 8 through a second connecting pipe, and a third electric control valve 9 is arranged on the second connecting pipe. The other end of the vacuum tank 5 is communicated with the vacuum drying cavity 1 through a third connecting pipe 7, and a fourth electric control valve 6 is arranged on the third connecting pipe 7.
The invention provides a depressurization method for vacuum drying of a supporting layer and a sealing layer, which comprises the following steps: and (5) performing instant depressurization operation. The transient step-down operation includes:
First, before depressurization, the fourth electronically controlled valve 6 is closed, and the vacuum tank 5 is previously evacuated to a low vacuum state.
Then, at the time of depressurization, the fourth electronically controlled valve 6 is opened so that the vacuum drying chamber 1 communicates with the vacuum tank 5 and instantaneously drops to the equilibrium low pressure within 0.5 seconds.
Finally, the vacuum pump 8 simultaneously extracts the gas phase components in the vacuum tank 5 and the vacuum drying cavity 1, so that after the vacuum degree in the vacuum drying cavity 1 accords with a preset target, the fourth electric control valve 6 and the first electric control switch valve 10 are closed, and simultaneously, the vacuum pump 8 continuously extracts the gas phase components in the vacuum tank 5 to a low vacuum state in the vacuum tank 5.
The invention provides a vacuum rapid drying method for a supporting layer and a sealing layer combined with instant depressurization operation, wherein the supporting layer is sequentially provided with at least three layers from a transition layer to the sealing layer, and the method comprises the following steps:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 14.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, while maintaining the vacuum in the vacuum tank 5.
And 14.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank 5.
And 14.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank 5.
Step 14.4, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, while maintaining the vacuum in the vacuum tank 5.
And 14.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank 5.
Step 14.6 repeating steps 14.4 and 14.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 15.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, while maintaining the vacuum in the vacuum tank 5.
And 15.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank 5.
And 15.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing the vacuum tank 5.
And 15.4, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, while maintaining the vacuum pumping of the vacuum tank 5.
And 15.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing the vacuum tank 5.
Step 15.6 repeating steps 15.4 and 15.5 until the second layer of the support layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 16.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, while maintaining the vacuum in the vacuum tank 5.
And step 16.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank 5.
And step 16.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 90 seconds, and continuously vacuumizing the vacuum tank 5.
Step 16.4, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, while maintaining the vacuum in the vacuum tank 5.
Step 16.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds, and the vacuum tank 5 continues to vacuumize.
Step 16.6 repeating steps 16.4 and 16.5 until the third layer of the support layer is dried.
The inner surface of the sealing layer is attached to the outer surface of the third layer of the supporting layer, and when the sealing layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 17.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 260-220 mmHg within 35 seconds, while maintaining the vacuum in the vacuum tank 5.
And step 17.2, the vacuum degree of the environment of the ceramic shell to be dried is restored to normal pressure within 120 seconds, and the vacuum tank 5 is continuously vacuumized.
Step 17.3 steps 17.1 and 17.2 are repeated until the encapsulation layer is dried.
The above-mentioned example technology combines the specific instant depressurization operation, can make the drying time of thick paste crust film further shorten, break strength coefficient further reduce, the average thickness of the ceramic crust supporting layer further promotes, thus realize keeping sufficient supporting force, make thick paste ceramic crust have excellent break strength coefficient too, has improved the applicable field in the precision casting of thick paste ceramic crust.
The invention provides a vacuum quick drying treatment method, which comprises the following steps: and putting the ceramic shells to be dried into a vacuum quick drying system, standing for 30-120 seconds, and performing vacuum quick drying treatment.
And during the standing period, the vacuum rapid drying system performs low-power drying on the ceramic shell to be dried.
Because the vacuum quick drying of the invention needs to promote the quick volatilization of the moisture of the thick slurry ceramic shell by means of wind with different intensities, if the vacuum drying cavity 1 is placed into the vacuum drying cavity 1 after the ceramic shell is completely sized, the fan is started according to the related intensity, on one hand, the scanning action of the scanning device and the control analysis of the fan group are not completed, and the fan group cannot determine the optimal running state, if the full-power running is adopted, on the other hand, the actual drying state of the ceramic shell 4 to be dried is different from the theoretical drying state obtained by the analysis, the difficulty of the subsequent control is increased, and on the other hand, the sand or the particle in the thick slurry ceramic shell slurry which is not coagulated is easily separated or enriched towards the leeward direction under the action of wind pressure, so that the drying quality of the ceramic shell is influenced.
By adopting the method of the example, the ceramic shells to be dried are placed into a vacuum rapid drying system and then are kept stand for 30-120 seconds. On the one hand, the scanning device can have enough time to complete scanning, and the control system has enough time to complete each control analysis, so that each fan in the fan set can operate based on a theoretical operation state, the actual drying state of the ceramic shell 4 to be dried is similar to the theoretical drying state obtained by analysis, and the uniformity of the drying degree of each part in the drying process of the ceramic shell 4 to be dried is effectively controlled. On the other hand, a vacuum rapid drying system with low power operation, such as a fan set with low power operation, can provide a drying rate which is better than natural drying without significantly affecting the actual drying progress, and improves the drying efficiency to a certain extent.
The ceramic shell sol defoaming agent accounting for 0.1 to 0.5 percent of the mass of the ceramic shell sol is added in the surface layer in an exemplary way.
The applicant has studied that the reason why the cast is sometimes rugged is that: when the ceramic shell is dried quickly by adopting a vacuum quick drying method, substances in the surface layer slurry are inevitably stirred to flow, and bubbles are possibly generated. If the formed bubbles are in the ceramic shell, cavities are formed in the surface ceramic shell, and uneven supporting force of the surface layer is caused. If the formed bubbles are on the surface of the ceramic shell of the surface layer, thin-layer bubble bulges are formed, and when high-temperature casting molten steel is poured into the ceramic shell, the thin-layer bubble bulges possibly burst, so that bubble grooves are formed on the surface layer, and bubble bulges are formed on the surface of the casting. It is also possible that the lamellar bubble projections do not burst, resulting in bubble grooves on the casting surface. The above problems all affect the accuracy of the casting.
In order to eliminate the influence, the invention adds a certain content of defoaming agent into the surface layer to eliminate the influence of bubbles possibly generated by the surface layer on casting precision.
In the invention, the foaming agent with the mass of 0.5-1% of that of the ceramic shell sol is added in the supporting layer in an exemplary way.
The applicant finds that sand and particles with higher content in the thick slurry can prevent the thick slurry ceramic shell from flowing and discharging and generating bubbles and flowing in the process of negative pressure-normal pressure reciprocating action in the process of researching the thick slurry ceramic shell vacuum drying, so that the formed sponge structure is relatively poor in uniformity.
Through research of the applicant, by adding a small amount of foaming agent into the thick slurry ceramic shell of the support layer, on one hand, the thick slurry can form a proper amount of micro bubbles under the action of shearing force (wiping-scraping-re-knife operation from a sizing process operator) in the slurry in the sizing process, and the micro bubbles have good fluidity, so that the sand is facilitated to penetrate into the support layer in the sand covering process, and the sand is easier to uniformly distribute. On the other hand, in the vacuum rapid drying process, the continuous change of the internal and external air pressure of the slurry can promote the formation of more microbubbles inside the slurry, thereby improving the fluidity of moisture and bubbles, promoting the rapid discharge of the moisture in the slurry, increasing the volume of the spongy structure of the thick slurry ceramic shell supporting layer, thickening the supporting layer and reducing the breaking strength coefficient, and obtaining the thick slurry ceramic shell suitable for precision casting.
The mass concentration of silicon dioxide in the mixed system of the ceramic shell sol, the powder and the water is controlled to be 22-25% in an exemplary manner.
The applicant has studied that in the concentrated ceramic shell slurry, which is the most of the cases used in the prior art, the mass concentration of silicon dioxide can reach or exceed 30%, namely, the concentration of the slurry is controlled by increasing the concentration of silica sol. Although an increase in the mass concentration of silica may promote easier desiccation of the slurry to form a gel. However: on the one hand, the too short gel time can lead to the reduction of the controllable drying rate adjustment allowance of each part in the ceramic shell drying process, and the drying rate of each part of the ceramic shell is difficult to realize uniform control, so that the problems that when the ceramic shell main body is dried, part of the ceramic shell is still incomplete, or part of the ceramic shell is already dried are solved. Meanwhile, the slurry is easy to lose water and coagulate in the sizing process to form gel, which is unfavorable for the multiple sizing operation of the ceramic shell. On the other hand, because the chemical properties of silicon dioxide are relatively unstable, when metal casting is carried out, the metal surface is oxidized to form oxidized metal and a large amount of heat is released, silicon dioxide is easy to react with metal oxide under the condition to form silicate with low melting point, and dense semicircular pits or rice crust-like attachments are formed near a casting gate or a hot junction part, so that the silicon dioxide reacts with metal to form a mold wall. The increase in silica content results in a significant increase in the likelihood of mold wall reactions and a significant decrease in casting accuracy.
Therefore, the applicant changes the proportioning mode of the existing thick-pulp ceramic shell slurry, maintains the concentration of silicon dioxide within a proper range of 22-25%, and increases the concentration of the slurry by increasing the particle filler and the sand-covered quantity to obtain the thick-pulp ceramic shell which is more suitable for precision casting.
For a more detailed explanation of the technical solutions of the present application, the following describes the techniques of the present application in further detail in conjunction with specific examples and comparative examples.
Preparing slurry:
(1) Thick stock a: ceramic shell slurry is prepared by compounding ceramic shell sol, powder, water and sand, and meets the following conditions: the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 58 seconds, the concentration of the transition ceramic shell slurry is 32 seconds, the concentration of the support ceramic shell slurry is 24 seconds, the concentration of the sealing ceramic shell slurry is 11 seconds, and the sealing layer does not contain sand. The surface layer is coated with 100 meshes of sand, the transition layer is coated with 60 meshes of sand, and the support layer is coated with 30 meshes of sand. The ceramic shell sol is silica sol, and the mass concentration of the silica is 25%. The powder comprises the following components: 300 mesh zirconium powder.
(2) Thick stock B: ceramic shell slurry is prepared by compounding ceramic shell sol, powder, water and sand, and meets the following conditions: the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 58 seconds, the concentration of the transition ceramic shell slurry is 32 seconds, the concentration of the support ceramic shell slurry is 24 seconds, the concentration of the sealing ceramic shell slurry is 11 seconds, and the sealing layer does not contain sand. The surface layer is coated with 100 meshes of sand, the transition layer is coated with 60 meshes of sand, and the support layer is coated with 30 meshes of sand. The surface layer is added with a defoaming agent accounting for 0.3 percent of the mass of the ceramic shell sol. The support layer is added with a foaming agent with the mass of 0.8% of that of the ceramic shell sol. The ceramic shell sol is silica sol, and the mass concentration of the silica is 25%. The powder comprises the following components: 300 mesh zirconium powder
(3) Grouting: ceramic shell slurry is prepared by compounding ceramic shell sol, powder, water and sand, and meets the following conditions: the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 45 seconds, the concentration of the transition ceramic shell slurry is 26 seconds, the concentration of the support ceramic shell slurry is 14 seconds, the concentration of the sealing ceramic shell slurry is 11 seconds, and the sealing layer does not contain sand. The surface layer is coated with 100 meshes of sand, the transition layer is coated with 60 meshes of sand, and the support layer is coated with 30 meshes of sand. The ceramic shell sol is silica sol, and the mass concentration of the silica is 25%. The powder comprises the following components: 300 mesh zirconium powder
The testing method comprises the following steps:
(1) Breaking strength coefficient:
taking the ceramic shells in the same batch, and carrying out dewaxing and high-temperature treatment at 1050 ℃ for 1.5 hours to obtain the ceramic shells for casting, wherein the maximum pressure born by the ceramic shells when the ceramic shells for casting are damaged is used as a breaking strength coefficient. The breaking strength coefficient of at least 5 ceramic shells is taken as the breaking strength coefficient of the embodiment or the comparative example after being averaged in the same batch.
(2) Ceramic shell thickness:
taking the ceramic shells of the same batch, and carrying out dewaxing and high-temperature treatment at 1050 ℃ for 1.5 hours to obtain the ceramic shells for casting. Taking the average value of the thickness of the ceramic shell at the casting ports of at least 5 ceramic shells for casting as the thickness of the ceramic shell, wherein the unit is cm.
(3) Drying time:
the average value of the drying time of each layer from the surface layer to the sealing layer of the ceramic shell 4 to be dried is rounded, and the drying time is expressed in min. The drying time of each layer is as follows: the ceramic shell 4 to be dried of the corresponding layer is put into a vacuum quick drying system until the drying of the layer is completed.
(4) Drying yield:
q% = (number of dried qualified ceramic shells of the batch)/(number of all ceramic shells of the batch) ×100% and is taken as an integer. The judgment standard of qualified ceramic shell drying is as follows: the dried ceramic shell does not have excessive drying phenomenon, and the humidity at the deep hole and the humidity at the surface of the ceramic shell are both lower than 3%.
The ceramic shell preparation method 1 comprises the following steps:
s1, coating ceramic shell slurry with the corresponding layers layer by layer outside the wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed.
S2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried.
When the vacuum rapid drying treatment is carried out, firstly, the model information of the ceramic shell to be dried is obtained, and then, the control parameters of all the blowers at different side directions of the ceramic shell to be dried are regulated according to the model information, so that the drying time trend of all parts of the whole ceramic shell to be dried is consistent.
S3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting.
The vacuum flash drying system includes: the vacuum drying device comprises a vacuum drying cavity 1, a vacuum pump 8, a control system, a first data transmission module, a second data transmission module, a local database module and a remote system module. The vacuum pump 8 performs vacuum pumping treatment on the vacuum drying cavity 1. The vacuum pump 8 is communicated with the vacuum drying cavity 1 through a first connecting pipe, and a first electric control switch valve 10 is arranged on the first connecting pipe. The vacuum drying cavity 1 is communicated with an air pipe 106, and a second electric control valve 107 is arranged on the air pipe 106.
The first data transmission module is connected with the remote system module through a signal line or a wireless network.
The local database module is used as a control parameter database for storing related deep hole-control parameter relation groups and operation result data.
And the remote system module collects deep hole-control parameter relation groups and operation result data of each vacuum quick drying system through the first data transmission module, and selects a deep hole-control parameter relation group corresponding to the optimal operation result from the same deep hole relation. And based on authorization permission and/or instructions and/or an automatic synchronization mode, the deep hole-control parameter relation group corresponding to the optimal operation result is concentrated through a remote system and then is synchronized into the local database module of each vacuum quick drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum quick drying system through the first data transmission module.
When the vacuum quick drying system calls the deep hole-control parameter relation group in the local database module, if a new optimal deep hole-control parameter relation group exists, the new optimal deep hole-control parameter relation group is preferentially called.
The remote system is connected with a control system signal of the vacuum quick drying system through a second data transmission module in a signal line connection or wireless network connection mode, so as to send remote control instructions to the control system and/or acquire control instructions sent by the control system and/or acquire operation state parameters of various electric control devices in the vacuum quick drying system.
The execution priority of the remote control instruction sent by the remote system is higher than the execution priority of the control instruction sent by the control system.
The drying frame 3 is detachably arranged in the vacuum drying cavity 1, and the ceramic shell 4 to be dried is detachably arranged on the drying frame 3 so as to be dried. The inside of vacuum drying chamber 1 is equipped with first blast air unit 101 at drying rack 3 top, is equipped with second blast air unit 102 in drying rack 3 bottom, cuts the third blast air unit 103 that sets up on vacuum drying chamber 1 switch door along vacuum drying chamber 1 at drying rack 3, is equipped with fourth blast air unit 104 and fifth blast air unit 105 respectively along vacuum drying chamber 1 axial both sides at drying rack 3, is equipped with adjustable component 108 at third blast air unit 103 contralateral, adjustable component 108 is: and a sixth blower unit.
The drying rack 3, as shown in fig. 1-2, comprises: and a ceramic shell hanging frame 304 for hanging the ceramic shell 4 to be dried. The ceramic shell hanging rack 304 is provided with a plurality of hanging grooves 305. The ceramic shell 4 to be dried is hooked at the hooking groove 305 through the hook 11. The bottom of the ceramic shell hanging frame 304 is fixedly provided with a hanging frame supporting plate 302. The bottom of the hanger bracket 302 is provided with a plurality of rollers 303 which can slide along the guide rail 301. The guide rail 301 is fixed to the bottom surface of the inside of the vacuum drying chamber 1.
The guide rail 301 is provided with a limiting block at one side far away from the vacuum drying cavity 1 to open and close the door. As shown in fig. 1, the guide rail 301 is provided with a stopper on a side close to the adjustable member 108.
The vacuum drying cavity 1 is internally provided with a three-dimensional detection mechanism 2. As shown in fig. 1 to 4, the three-dimensional detection mechanism 2 includes: two parallel X-axis guide rails 201 which are horizontally arranged along the axial direction of the vacuum drying cavity 1 and are respectively positioned at two sides of the drying frame 3, and Y-axis guide rails 202 which are horizontally arranged along the cutting direction of the vacuum drying cavity 1. The two X axial guide rails 201 are respectively provided with a first displacement device 203 capable of displacing along the X axial guide rail 201, and the Y axial guide rail 202 is fixed between the two first displacement devices 203 and is driven by the two first displacement devices 203 to displace along the X axial guide rail 201. The Y-axis guide 202 is provided with a second displacement device 204 that is displaceable along the Y-axis guide 202. The second displacement device 204 is provided with an electric control telescopic device 205 which stretches and contracts along the Z-axis direction along the vertical direction. The tail end of the telescopic end of the electric control telescopic device 205 is fixed with a scanning device 207 through an electric control cradle head 206. The first displacement device 203, the second displacement device 204, the electric control telescopic device 205 and the electric control cradle head 206 are respectively connected with a control system through signals.
The electrically controlled pan-tilt 206, as shown in fig. 5, includes: a stationary table 2061 fixed to the electrically controlled telescoping device 205, and a rotating table 2062 rotatably connected to the stationary table 2061 and rotatable about a vertical axis relative to the stationary table 2061. The rotating table 2062 is rotatably connected with the fixed end of the second electric control telescoping device 2064 through a speed reducer 2063, and the speed reducer 2063 controls the second electric control telescoping device 2064 to rotate along the horizontal shaft. The telescoping end of the second electrically controlled telescoping device 2064 holds the scanning device 207.
As shown in fig. 6, the scanning device 207 includes: an imaging device 2071, a thermal imager 2072, a scanning distance measuring device 2073 and an infrared temperature measuring device 2074. The camera 2071 is used for acquiring image data of the ceramic shell 4 to be dried. The scanning distance measuring device 2073 is used for measuring the distance between the ceramic shell 4 to be dried and the scanning device 207 in real time.
The control system includes: the device comprises a vacuum drying control module, a fan set control module, a ceramic shell analysis module, a scanning device control module and a drying process analysis module.
The vacuum drying control module controls the opening and closing of the vacuum pump 8, the first electric control switch valve 10 and the second electric control valve 107.
The ceramic shell analysis module acquires image data of the ceramic shell 4 to be dried and performs model structure analysis to obtain the position, the orientation and the depth of the deep hole of the ceramic shell 4 to be dried, and sends the deep hole to the fan set control module. And after the fan set control module performs fan set control analysis according to the deep hole position, the direction and the depth of the ceramic shell 4 to be dried, the on-off and/or control parameters of each fan set are controlled according to the analysis result.
The scanning device control module is used for controlling the movements of the two first displacement devices 203, the second displacement devices 204, the electric control telescopic devices 205 and the electric control cradle head 206, so that the scanning device 207 performs omnibearing shooting/scanning on the ceramic shell 4 to be dried to obtain image/scanning data of the ceramic shell 4 to be dried.
The drying process analysis module obtains the measured quantity of the infrared temperature measuring device 2074 to carry out drying process analysis so as to judge whether the ceramic shell 4 to be dried is dried.
The model structure analysis method comprises the following steps:
step 1.1, the scanning distance measuring device 2073 performs omnibearing scanning on the surface n of the ceramic shell 4 to be dried according to a preset line to obtain a distance measuring data set Gn of all scanning points of the surface n relative to the scanning distance measuring device 2073.
And step 1.2, connecting the end points of the ranging data set Gn to obtain a digital surface m of the surface n of the ceramic shell 4 to be dried.
And 1.3, carrying out graphic analysis on the digital surface m of the ceramic shell 4 to be dried by combining the image data, and determining the basic surface, the convex surface and the concave surface of the digital surface m.
Step 1.4, calculating a difference Cmk-b of each ranging point in the groove surface relative to each ranging point of the adjacent basic surface of the groove, wherein mk is a groove with a number k on the digital surface m, and b is an additional number of the ranging point in the groove mk.
Step 1.5, cmk-b > K2 is taken as a deep hole, and Cmk-b > K3 is taken as a through hole. Wherein K2 is a preset deep hole judgment threshold value, and K3 is a model width or a model length or a model height corresponding to the surface n of the ceramic shell 4 to be dried.
And 1.6, counting the positions Wmc of all deep holes on the digital surface m of the ceramic shell 4 to be dried and the depth Hmc corresponding to each deep hole, wherein c is the natural number of the deep holes on the digital surface m.
Step 1.7 repeating the steps 1.1 to 1.6 until the positions Wmc and the depths Hmc of deep holes on the surface of the ceramic shell 4 to be dried, which can be scanned, are counted, and determining the orientation Xmc of the deep holes according to the surface n of the deep holes.
And step 1.8, outputting data of the positions Wmc, the depths Hmc and the orientations Xmc of deep holes on the whole surface of the ceramic shell 4 to be dried.
And 2.1, controlling the scanning distance measuring device 2073 to move to the deep hole position according to the deep hole position.
Step 2.2, obtaining a plurality of deep hole depth measurement data by adjusting the orientation of the relative deep holes of the scanning distance measuring device 2073.
And 2.3, correcting the depth data Hm-c of the original deep hole by using the depth measurement data with the deepest depth to obtain corrected data Hm-c'.
The method for acquiring the basic surface, the convex surface and the concave surface comprises the following steps:
and 1.3.1, acquiring image data corresponding to the digital surface m of the ceramic shell 4 to be dried, and splicing the image data to obtain an image surface R.
Step 1.3.2, element recognition is performed on the image plane R to obtain element regions rn-m on the image plane R, wherein rn is the sequence number of the element regions in the digital surface m.
Step 1.3.3 the digital surface m is adjusted to the same orientation and similar size as the image plane R.
Step 1.3.4 takes an element region rc-m with the largest continuous area as a basic surface, wherein the rc-m belongs to rn-m.
And 1.3.5, acquiring distance measurement point data of each non-basic surface element area, wherein element area distance measurement points with a distance greater than that of adjacent basic surface distance measurement points are groove points, and element area distance measurement points with a distance less than that of adjacent basic surface distance measurement points are raised points.
Step 1.3.6, using the element area as a boundary, connecting adjacent groove points and protruding points to form a groove surface and a protruding surface.
The drying process analysis includes: the temperature T inside the borehole is measured periodically or continuously. And (3) making a curve Qv of the deep hole temperature Tv-the drying time t, and when all the Qv have curve sections conforming to a preset curve rule, indicating that the drying of the ceramic shell 4 to be dried is completed. Wherein v is the natural number of all deep holes of the ceramic shell 4 to be dried.
The preset curve rule, as shown in fig. 9, includes: the temperature T in the deep hole gradually decreases to a temperature T2 along with the drying time from the initial drying temperature T1, then gradually increases to the ambient drying temperature T3 along with the drying time, and when the temperature T of the deep hole of the ceramic shell 4 to be dried is subjected to T1-T2-T3 and the ambient drying temperature T3 is maintained for a preset time U, the completion of drying is judged. The initial drying temperature T1 is 22-26 ℃, the temperature T2 is 5-7 ℃ lower than the temperature T1, and the ambient drying temperature T3 is 24+/-1 ℃.
When the ceramic shells 4 to be dried are plural, the method for judging the drying completion of the ceramic shells 4 to be dried comprises the following steps: detecting the temperature of each deep hole of each ceramic shell 4 to be dried one by one, and judging that the drying of the ceramic shells 4 to be dried is finished in the whole batch when more than L% of the ceramic shells 4 to be dried are dried. The ratio of L% = (Lg-d)/(L0-d) is 100%, where Lg-d is the number of dried ceramic shells 4 in the batch d, and L0-d is the number of all ceramic shells 4 in the batch d. Wherein the value of L% is as follows: 100 percent or more, L percent or more, E percent or more. Wherein E is a preset threshold for the minimum drying completion percentage of all ceramic shells 4 to be dried for batch d.
The fan set control analysis includes: a fan set control analysis method A, a fan set control analysis method B, a fan set control analysis method C and a fan set control analysis method D. Wherein:
the fan set control analysis method A comprises the following steps:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells 4 to be dried, the following method is adopted:
and 3.1, obtaining the total number D0 of all deep holes of the ceramic shell 4 to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell 4 to be dried of the facing fan group p. And p is the number of the fan set arranged on different sides in the vacuum drying cavity 1.
Step 3.2 calculates kS-p% = Dp/D0 x 100%, where kS-p% is the control parameter of fan set p.
Step 3.3 steps 3.1 to 3.2 are repeated until the kS-p% of the total set of fans is obtained.
For all the fan groups p facing the surface of the ceramic shell 4 to be dried without deep holes, the following method is adopted:
calculating kF-p% = [ 1-D0/(D0+1) ], wherein kF-p% is a control parameter of the fan group p.
The fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
The fan set control analysis method B comprises the following steps:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells 4 to be dried, the following method is adopted:
and 4.1, obtaining the total number D0 of all deep holes of the ceramic shell 4 to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell 4 to be dried of the facing fan group p. And P is the serial number of the fan set arranged on different sides in the vacuum drying cavity 1.
And 4.2, obtaining kS-p% from a control parameter database according to the numbers of D0 and Dp. The kS-p% is a control parameter of the fan group p.
Step 4.3 steps 4.1 to 4.2 are repeated to obtain kS-p% of the total fan set.
For all the fan groups p facing the surface of the ceramic shell 4 to be dried without deep holes, the following method is adopted:
and obtaining kF-p% from a control parameter database according to the total number D0 of all deep holes of the ceramic shell 4 to be dried. The kF-p% is a control parameter of the fan group p.
The fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
Said entering k in the control parameter database S-p % and kF-p% method comprising:
step 5.1 simulates the same fan set position and orientation as the target vacuum drying chamber 1 in the simulation device.
Step 5.2, presetting deep hole distribution conditions of different ceramic shells 4 to be dried for drying training, and determining control parameters k of each fan set p corresponding to optimal drying time under each deep hole distribution condition when the fan set p is relatively fully loaded S-p % and kF-p%; the deep hole distribution condition comprises: deep holeOrientation and number; the optimal drying time is the shortest time for synchronously drying deep holes and surface layers of each surface of the ceramic shell 4 to be dried;
step 5.3 repeating the step 5.2 until training of deep hole distribution under normal conditions is completed, and constructing D0-Dp-k S-p And (3) a deep hole-control parameter relation group of%kF-p% and storing the deep hole-control parameter relation group into a control parameter database.
The fan set control analysis method C comprises the following steps:
step 6.1 constructs a three-dimensional coordinate system based on a scanning start point preset by the scanning device 207.
And 6.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device 207, and marking the three-dimensional coordinate point on the position, the orientation and the depth of the deep hole of the ceramic shell 4 to be dried in the model structure analysis process.
And 6.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fans in the fan set p.
And 6.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area.
Step 6.5 calculates kup-e% = (Dup-e/Dup) ×ks-p%.
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load. For the fan corresponding to Dup-e=0, it is operated at the lowest power.
The fan set control analysis method D comprises the following steps:
step 7.1 constructs a three-dimensional coordinate system based on a scanning start point preset by the scanning device 207.
And 7.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device 207, and marking the three-dimensional coordinate point on the position, the orientation and the depth of the deep hole of the ceramic shell 4 to be dried in the model structure analysis process.
And 7.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fans in the fan set p.
And 7.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area.
Step 7.5, acquiring kup-e% of corresponding fans from a control parameter database according to Dup and Dup-e, wherein kup-e% are control parameters of fans with numbers e in the fan group p.
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load.
The method for inputting kup-e% into the control parameter database specifically comprises the following steps:
step 8.1 simulates the same fan set position and orientation as the target vacuum drying chamber 1 in a simulation device.
And 8.2, presetting deep hole distribution conditions of different ceramic shells 4 to be dried for drying training, and determining the running proportion kup-e% of each fan in each fan group p corresponding to the optimal drying time under each deep hole distribution condition when the fans are fully loaded. The deep hole distribution condition comprises: deep hole orientation and number. The optimal drying time is the shortest time for the deep holes and the surface layers of each surface of the ceramic shell 4 to be dried synchronously.
And 8.3, repeating the step 8.2 to the conventional deep hole distribution condition training, constructing a deep hole-control parameter relation group of Dup-e-kup-e%, and storing the deep hole-control parameter relation group in a control parameter database.
The drying of the ceramic shells 4 to be dried, for which the input data exist in the control parameter database, is performed by adopting a fan set control analysis method B+D, and the drying of the ceramic shells 4 to be dried, for which the input data do not exist in the control parameter database, is performed by adopting a fan set control analysis method A+C.
The method for enabling the drying time of all parts of the whole ceramic shell to be dried to be consistent comprises the following steps:
step 9.1, performing real-time thermal imaging shooting on the ceramic shell 4 to be dried along with the scanning device 207 by the thermal imager 2072 in the drying process of the ceramic shell 4 to be dried, and sending the shooting to a control system.
And 9.2, the control system judges whether an area T with the temperature difference exceeding a preset temperature difference threshold exists according to the thermal imaging graph when the drying time exceeds the preset first drying time according to the heat distribution condition in the thermal imaging graph, and if the area T exists, the control system judges and operates as follows:
and when the temperature of the low-temperature area of the area T is lower than a preset low-temperature threshold value, reducing the operation power of the fan set corresponding to the area T.
And when the temperature of the high-temperature area of the area T is higher than a preset high-temperature threshold value, increasing the operating power of the area T corresponding to the fan set.
When the existence time of the area T exceeds a preset time threshold, the temperature of a low-temperature area of the area T is higher than a preset low-temperature threshold, and the temperature of a high-temperature area of the area T is lower than a preset high-temperature threshold, the operation power of the area T corresponding to the fan set is increased.
The preset low temperature threshold is: 14 ℃.
The preset high temperature threshold is: 27 ℃.
The preset first drying time is: 2 minutes.
The preset time threshold is: 50 seconds.
And (3) putting the ceramic shells to be dried into a vacuum quick drying system, standing for 60 seconds, and then carrying out vacuum quick drying treatment. The vacuum rapid drying treatment method comprises the following steps:
drying the surface layer: firstly, the vacuum degree of the environment of the ceramic shell to be dried is reduced to 750-720 mmHg from normal pressure within 5 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 5 seconds from 750 to 720 mmHg. And (5) circulating the process until the surface layer is dried.
When the transition layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 720-680 mmHg within 7 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 7 seconds from 720 to 680 mmHg. And (5) repeating the above process circularly until the transition layer is dried.
The supporting layer is equipped with at least three-layer in proper order from the transition layer to seal between the layer, when drying to the supporting layer, includes following step:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 11.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
And 11.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes.
Step 11.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
Step 11.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.6 repeating steps 11.4 and 11.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 12.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
And 12.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 12.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
Step 12.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.6 repeating steps 12.4 and 12.5 until the second layer of the support layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 13.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
And 13.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 13.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
Step 13.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.6 repeating steps 13.4 and 13.5 until the third layer of the support layer is dried.
And the inner surface of the closed layer is attached to the outer surface of the third layer of the supporting layer.
When the sealing layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 120-90 mmHg within 40 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 120 seconds. And (5) repeating the process circularly until the sealing layer is dried.
The ceramic shell preparation method 2 comprises the following steps:
s1, coating ceramic shell slurry with the corresponding layers layer by layer outside the wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed.
S2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried.
S3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting.
The vacuum flash drying system includes: a vacuum drying cavity 1, a vacuum pump 8 and a control system. The vacuum pump 8 performs vacuum pumping treatment on the vacuum drying cavity 1. The vacuum pump 8 is communicated with the vacuum drying cavity 1 through a first connecting pipe, and a first electric control switch valve 10 is arranged on the first connecting pipe. The vacuum drying cavity 1 is communicated with an air pipe 106, and a second electric control valve 107 is arranged on the air pipe 106.
The drying frame 3 is detachably arranged in the vacuum drying cavity 1, and the ceramic shell 4 to be dried is detachably arranged on the drying frame 3 so as to be dried. The inside of vacuum drying chamber 1 is equipped with first blast air unit 101 at drying rack 3 top, is equipped with second blast air unit 102 in drying rack 3 bottom, cuts the third blast air unit 103 that sets up on vacuum drying chamber 1 switch door along vacuum drying chamber 1 at drying rack 3, is equipped with fourth blast air unit 104 and fifth blast air unit 105 respectively along vacuum drying chamber 1 axial both sides at drying rack 3, is equipped with adjustable component 108 at third blast air unit 103 contralateral, adjustable component 108 is: and a sixth blower unit.
And (3) putting the ceramic shells to be dried into a vacuum quick drying system, standing for 60 seconds, and then carrying out vacuum quick drying treatment. The vacuum rapid drying treatment method comprises the following steps:
drying the surface layer: firstly, the vacuum degree of the environment of the ceramic shell to be dried is reduced to 750-720 mmHg from normal pressure within 5 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 5 seconds from 750 to 720 mmHg. And (5) circulating the process until the surface layer is dried.
When the transition layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 720-680 mmHg within 7 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 7 seconds from 720 to 680 mmHg. And (5) repeating the above process circularly until the transition layer is dried.
The supporting layer is equipped with at least three-layer in proper order from the transition layer to seal between the layer, when drying to the supporting layer, includes following step:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 11.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
And 11.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes.
Step 11.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 260-220 mmHg within 30 seconds.
Step 11.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 40 seconds.
Step 11.6 repeating steps 11.4 and 11.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 12.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
And 12.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 12.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 200-150 mmHg within 30 seconds.
Step 12.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 60 seconds.
Step 12.6 repeating steps 12.4 and 12.5 until the second layer of the support layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
Step 13.1 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
And 13.2, maintaining the vacuum degree of the environment of the ceramic shell to be dried in a negative pressure state for 4-6 minutes.
Step 13.3, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.4 the vacuum level of the ceramic shell environment to be dried is reduced from normal pressure to 80-20 mmHg within 30 seconds.
Step 13.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds.
Step 13.6 repeating steps 13.4 and 13.5 until the third layer of the support layer is dried.
And the inner surface of the closed layer is attached to the outer surface of the third layer of the supporting layer.
When the sealing layer is dried: the vacuum level of the ceramic shell environment to be dried is firstly reduced from normal pressure to 120-90 mmHg within 40 seconds. The vacuum in the environment of the ceramic shell to be dried is then restored to normal pressure within 120 seconds. And (5) repeating the process circularly until the sealing layer is dried.
And when the vacuum quick drying treatment is carried out, the control system controls the fan set in the vacuum quick drying system to operate at a fixed wind direction and rated power. And drying each layer of ceramic shell according to the working experience or the operation instruction after the drying for a preset time.
The ceramic shell preparation method 3 comprises the following steps:
s1, coating ceramic shell slurry with the corresponding layers layer by layer outside the wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed.
S2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried.
S3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting.
Step S2 is carried out by adopting a ceramic shell rapid drying method and device of ZL 201610416881.4.
Example 1
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 1 in the form of thick slurry B.
Example 2
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 2 in the form of thick slurry B.
Example 3
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 3 in the form of thick slurry B.
Comparative example 1
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 1 in the form of thick slurry A.
Comparative example 2
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 1 through grout. In order to achieve a comparable supporting force for the ceramic shells obtained in example 1, the number of layers of the supporting layer was 5.
Comparative example 3
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 3 through grout. In order to achieve a comparable supporting force for the ceramic shells obtained in example 1, the number of layers of the supporting layer was 5.
Comparative example 4
A ceramic shell, the structure of which is shown in fig. 7, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 3 through grout. The ceramic shell is prepared from thick slurry B, and is dried by adopting normal pressure and hot air at 120 ℃ in the drying process.
The ceramic shells obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to breaking strength coefficient, ceramic shell thickness, total drying time, and dry yield test, and the test results thereof are shown in Table 1.
Table 1. Results of the breaking strength coefficient, the ceramic shell thickness, the total drying time and the dry yield of examples 1 to 3 and comparative examples 1 to 3 are shown.
As can be seen from the table above:
(1) As can be seen from comparison of example 1 and example 2, compared with the technology adopting multidirectional fixed wind direction and fixed fan power, the method has the advantages that the control parameters of each direction fan are adjusted during ceramic shell drying, and under the control of the same control parameters such as vacuum degree and the like, the drying time of the ceramic shell is slightly improved, but the drying time of each part of the ceramic shell is almost consistent during the ceramic shell drying process, so that the drying yield of the ceramic shell is obviously improved.
(2) As can be seen from the comparison of the examples 1 and 3, the ceramic shell performance obtained by the invention is obviously improved and the drying yield of the ceramic shell is also obviously improved when the thick slurry ceramic shell is dried compared with the existing vacuum rapid drying technology. Embodiment 3 is mainly because the prior art adopts a mode of fixing wind and rotating the ceramic shell at two sides to carry out vacuum rapid drying, when the deep hole faces the windward side, the drying time is relatively short, when the deep hole faces the leeward side, the drying time is relatively long, and the problem of excessive drying of the windward side is easy to occur, namely the drying yield of the ceramic shell is reduced.
(3) As can be seen from comparison of comparative examples 1 and 4, the invention significantly improves the performance of the thick slurry ceramic shell, the breaking strength coefficient of the thick slurry ceramic shell is significantly reduced, and the thickness of the ceramic shell is significantly increased.
(4) As is clear from the comparison between example 1 and comparative example 1, the present invention can reduce the problem of the decrease in casting precision due to the generation of bubbles in the facing layer by adding the antifoaming agent to the facing layer using the prior art (no antifoaming agent and foaming agent added). Meanwhile, the thickness of the ceramic shell is further improved, the breaking strength coefficient is further reduced, the prepared ceramic shell is more suitable for precision casting, and the shell breaking and the piece taking are easier to carry out by adding the foaming agent into the supporting layer.
(5) As can be seen from comparison of the example 1, the comparative example 2 and the comparative example 3, the invention can promote the expansion of the ceramic shell supporting layer to obtain the ceramic shell supporting layer with higher thickness, and reduce the breaking strength coefficient of the ceramic shell. Because of the low material content, the expandable ceramic shell thickness is low compared to the thick slurry ceramic shell, and therefore, in order to achieve the necessary ceramic shell thickness to support the ceramic shell with sufficient support force, the number of layers of the support layer needs to be increased, resulting in an increase in the overall drying time (number of layers x drying time).
(6) As can be seen from comparison of the examples 1, 3 and 4, the drying yield of the thick paste ceramic shell prepared by the method is improved remarkably, which is mainly beneficial to the fact that the drying time is shortened remarkably while the drying process tends to be consistent. And when the thick paste ceramic shell is dried in the prior art, the drying time is too long. The ceramic shell drying is a cooling process of moisture volatilization, namely the temperature of the ceramic shell is reduced by about 6 ℃ during the moisture volatilization of the ceramic shell, and the wax mould is cooled and contracted under the influence of the low temperature of the ceramic shell. When the drying time is too long, the shrinkage ratio of the wax mould can be increased, so that the shrinkage ratio of the ceramic shell after drying is relatively large, and when the whole ceramic shell is dried, the whole ceramic shell can be warmed to the room temperature, at the moment, the wax mould can expand, and the expansion crack is formed at the joint part of the ceramic shell surface layer and the wax mould, so that the drying yield of the ceramic shell is seriously affected. The drying time is shorter, the shrinkage ratio of the wax mould is smaller under the influence of low temperature, and the crack expansion at the joint part of the ceramic shell surface layer and the wax mould is generally avoided, so that the drying yield of the thick slurry ceramic shell is improved.
Example 4
A ceramic shell, the structure of which is shown in fig. 6, comprises a deep hole 401 and a holding part 402. The deep hole 401 is a cast structure, and the grip portion 402 is a member gripped by a worker during sizing, and is not a cast structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 4 in the form of thick slurry B. The following differences exist between the ceramic shell preparation method 4 and the ceramic shell preparation method 1:
1. the vacuum flash drying system further comprises: a vacuum tank 5. One end of the vacuum tank 5 is communicated with the vacuum pump 8 through a second connecting pipe, and a third electric control valve 9 is arranged on the second connecting pipe. The other end of the vacuum tank 5 is communicated with the vacuum drying cavity 1 through a third connecting pipe 7, and a fourth electric control valve 6 is arranged on the third connecting pipe 7.
2. When the support layer and the sealing layer are subjected to vacuum rapid drying, the following method is adopted:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 14.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, while maintaining the vacuum in the vacuum tank 5.
And 14.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank 5.
And 14.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank 5.
Step 14.4, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, while maintaining the vacuum in the vacuum tank 5.
And 14.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank 5.
Step 14.6 repeating the steps 14.4 and 14.5 until the first layer of the support layer is dried.
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 15.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, while maintaining the vacuum in the vacuum tank 5.
And 15.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank 5.
And 15.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing the vacuum tank 5.
And 15.4, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, while maintaining the vacuum pumping of the vacuum tank 5.
And 15.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing the vacuum tank 5.
Step 15.6 repeating the steps 15.4 and 15.5 until the second layer of the supporting layer is dried.
The inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 16.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, while maintaining the vacuum in the vacuum tank 5.
And step 16.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank 5.
And step 16.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to return to normal pressure within 90 seconds, and continuously vacuumizing the vacuum tank 5.
Step 16.4, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, while maintaining the vacuum in the vacuum tank 5.
Step 16.5, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 90 seconds, and the vacuum tank 5 continues to vacuumize.
Step 16.6 repeating the steps 16.4 and 16.5 until the third layer of the support layer is dried.
The inner surface of the sealing layer is attached to the outer surface of the third layer of the supporting layer, and when the sealing layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 17.1, performing instant depressurization, and reducing the vacuum degree of the ceramic shell environment to be dried from instant equilibrium low pressure to 260-220 mmHg within 35 seconds, while maintaining the vacuum in the vacuum tank 5.
And step 17.2, the vacuum degree of the environment of the ceramic shell to be dried is restored to normal pressure within 120 seconds, and the vacuum tank 5 is continuously vacuumized.
Step 17.3 repeating steps 17.1 and 17.2 until the encapsulation layer is dried.
The transient step-down operation includes:
first, before depressurization, the fourth electronically controlled valve 6 is closed, and the vacuum tank 5 is previously evacuated to a low vacuum state.
Then, at the time of depressurization, the fourth electronically controlled valve 6 is opened so that the vacuum drying chamber 1 communicates with the vacuum tank 5 and instantaneously drops to the equilibrium low pressure within 0.5 seconds.
Finally, the vacuum pump 8 simultaneously extracts the gas phase components in the vacuum tank 5 and the vacuum drying cavity 1, so that after the vacuum degree in the vacuum drying cavity 1 accords with a preset target, the fourth electric control valve 6 and the first electric control switch valve 10 are closed, and simultaneously, the vacuum pump 8 continuously extracts the gas phase components in the vacuum tank 5 to a low vacuum state in the vacuum tank 5.
The ceramic shells obtained in example 1 and example 4 were subjected to breaking strength coefficient, ceramic shell thickness, total drying time, and dry yield test, and the test results are shown in table 2.
Table 2. Results of the breaking strength coefficient, the ceramic shell thickness, the total drying time, and the dry yield test of example 1 and example 4 are shown.
As can be seen from the table above:
the breaking strength coefficient of the ceramic shell can be further reduced through the instant depressurization action, and the thickness of the ceramic shell is further improved, so that the thick slurry ceramic shell also has an excellent breaking strength coefficient while maintaining enough supporting force, and the application field of the thick slurry ceramic shell in precision casting is improved.
Example 5
The ceramic shell is of a conventional structure as shown in fig. 10 and is provided with a holding part 402, wherein the holding part 402 is a part held by a worker during sizing and is not of a casting structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 1 in the form of thick slurry B.
Example 6
The ceramic shell is of a conventional structure as shown in fig. 10 and is provided with a holding part 402, wherein the holding part 402 is a part held by a worker during sizing and is not of a casting structure. The ceramic shell is prepared by adopting a ceramic shell preparation method 2 in the form of thick slurry B.
The ceramic shells obtained in examples 1-2 and examples 5-6 were subjected to breaking strength coefficient, ceramic shell thickness, total drying time, and dry yield test, and the test results are shown in Table 3.
Table 3. Results of the breaking strength coefficients, the ceramic shell thicknesses, the total drying times, and the dry yields of examples 1-2 and examples 5-6 are shown.
As can be seen from the table above:
(1) When the configuration of the member to be cast is simpler, compared with the technology of fixing the wind direction, the method has the advantages that the total drying time and the drying yield are closer.
(2) When the configuration of the member to be cast is complex, compared with the technology of fixing the wind direction, the total drying time is slightly increased, but the drying yield can be obviously improved.
Therefore, when the ceramic shell preparation method is adopted to prepare the ceramic shell with a simple configuration, the preparation efficiency and the preparation success rate are similar to those of a fixed wind technology, and when the ceramic shell with a complex configuration is prepared by the breaking coefficient, the technical effect can be obviously improved. Therefore, the ceramic shell preparation method not only has better performance, but also is suitable for the preparation of ceramic shells with various configurations, has wide applicability, and is particularly suitable for the preparation of ceramic shells with complex configurations.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (46)
1. The preparation method of the ceramic shell for precision casting is characterized by comprising the following steps:
s1, coating ceramic shell slurry with the corresponding layers layer by layer outside a wax mould, and sequentially obtaining ceramic shells to be dried with the corresponding layers after each coating of the ceramic shell slurry is completed;
s2, placing the ceramic shells to be dried of each corresponding layer into a vacuum quick drying system for vacuum quick drying treatment, and performing coating operation on the ceramic shell slurry of the next layer after the ceramic shells of the layers are dried;
when the vacuum rapid drying treatment is carried out, firstly, model information of the ceramic shell to be dried is obtained, and then, control parameters of all air blowers at different side directions of the ceramic shell to be dried are regulated according to the model information, so that drying time tends to be consistent in all parts of the whole ceramic shell to be dried;
s3, drying all layers of ceramic shells to obtain the ceramic shell for precision casting.
2. The method for preparing the ceramic shell for precision casting according to claim 1, wherein the ceramic shell slurry is prepared by compounding ceramic shell sol, powder, water and sand, and is characterized in that:
the concentration of each layer of ceramic shell slurry was expressed in a Zahn cup number 4, using the Zahn cup method, wherein: the concentration of the surface ceramic shell slurry is 55-60 seconds, the concentration of the transition ceramic shell slurry is 30-35 seconds, the concentration of the support ceramic shell slurry is 22-25 seconds, the concentration of the sealing ceramic shell slurry is 10-12 seconds, and the sealing layer does not contain sand.
3. The method for preparing ceramic shells for precision casting according to claim 2, wherein the sand material is added into a mixed system of ceramic shell sol, powder and water in a sand-covering treatment mode, and the sand-covering treatment comprises: and (3) sand spraying treatment and/or floating sand treatment.
4. The method for producing ceramic shells for precision casting according to claim 3, wherein 100 mesh sand is selected when the ceramic shells to be dried are covered with sand on the surface layer, 60 mesh sand is selected when the ceramic shells to be dried are covered with sand on the transition layer, and 35-22 mesh sand is selected when the ceramic shells to be dried are covered with sand on the support layer.
5. The method for producing a ceramic shell for precision casting according to claim 3, wherein the sand shower treatment comprises:
firstly, performing first sand spraying treatment on the ceramic shell to be dried at a height position 10-30cm away from the ceramic shell to be dried;
and then, carrying out second to Nth sand spraying treatment, and gradually lifting the sand spraying height by 3-5cm compared with the sand spraying treatment of the last time until the sand spraying treatment is finished.
6. A method of producing a ceramic shell for precision casting according to claim 3, wherein the floating sand treatment comprises:
firstly, putting a ceramic shell to be dried into a floating sand machine, and starting a floating sand fan to enable sand materials in the floating sand machine to float and cover the surface of the ceramic shell to be dried;
Then stopping the floating sand blower to enable sand materials in the floating sand blower to be static and stacked around the ceramic shell to be dried, and standing for a period of time;
repeating the two steps until the floating sand treatment is completed.
7. The method for producing a ceramic shell for precision casting according to claim 1, wherein the vacuum rapid drying system comprises: the vacuum drying device comprises a vacuum drying cavity (1), a vacuum pump (8) and a control system; the vacuum pump (8) performs vacuumizing treatment on the vacuum drying cavity (1); the vacuum pump (8) is communicated with the vacuum drying cavity (1) through a first connecting pipe, and a first electric control switch valve (10) is arranged on the first connecting pipe; the vacuum drying cavity (1) is communicated with an air pipe (106), and a second electric control valve (107) is arranged on the air pipe (106);
the drying rack (3) is detachably arranged in the vacuum drying cavity (1), and the ceramic shell (4) to be dried is detachably arranged on the drying rack (3) so as to perform drying treatment; at least two groups of fan sets with different wind directions are arranged around the drying frame (3) in the vacuum drying cavity (1);
the control system includes: a vacuum drying control module and a fan set control module; the vacuum drying control module controls the opening and closing of the vacuum pump (8), the first electric control switch valve (10) and the second electric control valve (107), and the fan set control module controls the opening and closing and/or control parameters of all fan sets.
8. The preparation method of the ceramic shell for precision casting according to claim 7, wherein a first blower unit (101) is arranged at the top of a drying frame (3) in the vacuum drying cavity (1), a second blower unit (102) is arranged at the bottom of the drying frame (3), a third blower unit (103) which is arranged on a switch door of the vacuum drying cavity (1) along the cutting direction of the vacuum drying cavity (1) of the drying frame (3), and a fourth blower unit (104) and a fifth blower unit (105) are respectively arranged at two sides of the axial direction of the vacuum drying cavity (1) of the drying frame (3).
9. The method for preparing the ceramic shell for precision casting according to claim 8, wherein an adjustable component (108) is arranged at the opposite side of the third blower unit (103) in the vacuum drying cavity (1); the adjustable member (108) is: a condenser or a sixth blower unit.
10. The method for producing a ceramic shell for precision casting according to any one of claims 7 to 9, characterized in that the vacuum drying chamber (1) is provided with a controller assembly; the controller component receives control signals and sends the control signals to the fan group control module so as to control the on-off and/or control parameters of each fan group.
11. The method of manufacturing a ceramic shell for precision casting according to claim 10, wherein the controller comprises: at least one of a knob controller, a key controller, a touch screen controller and a toggle switch.
12. The method for preparing the ceramic shell for precision casting according to any one of claims 7 to 9, characterized in that a three-dimensional detection mechanism (2) is arranged inside the vacuum drying cavity (1); the three-dimensional detection mechanism (2) drives the scanning device (207) to move along an X axis, a Y axis and a Z axis;
the scanning device (207) comprises at least: an imaging device (2071); the camera device (2071) is used for acquiring image data of the ceramic shell (4) to be dried;
the control system includes: a ceramic shell analysis module; the ceramic shell analysis module acquires image data of the ceramic shell (4) to be dried and performs model structure analysis to obtain the position, the orientation and the depth of a deep hole of the ceramic shell (4) to be dried, and sends the deep hole to the fan set control module; and after the fan group control module performs fan group control analysis according to the deep hole position, the direction and the depth of the ceramic shell (4) to be dried, controlling the on-off and/or control parameters of each fan group according to the analysis result.
13. The method for producing a ceramic shell for precision casting according to claim 12, wherein the three-dimensional detecting mechanism (2) comprises: two X axial guide rails (201) which are parallel to each other and are respectively positioned at two sides of the drying rack (3) are horizontally arranged along the axial direction of the vacuum drying cavity (1), and Y axial guide rails (202) which are horizontally arranged along the tangential direction of the vacuum drying cavity (1); the two X axial guide rails (201) are respectively provided with a first displacement device (203) capable of displacing along the X axial guide rails (201), the Y axial guide rails (202) are fixed between the two first displacement devices (203), and the two first displacement devices (203) drive the X axial guide rails (201) to displace; the Y-axis guide rail (202) is provided with a second displacement device (204) which can displace along the Y-axis guide rail (202); an electric control telescopic device (205) which stretches along the Z-axis direction is arranged on the second displacement device (204) along the vertical direction; the tail end of the telescopic end of the electric control telescopic device (205) is fixed with a scanning device (207) through an electric control cradle head (206); the first displacement device (203), the second displacement device (204), the electric control telescopic device (205) and the electric control cradle head (206) are respectively connected with a control system through signals.
14. The method of preparing a ceramic shell for precision casting according to claim 13, wherein the control system comprises: a scanning device control module; the scanning device control module is used for controlling the movement of the two first displacement devices (203), the second displacement devices (204), the electric control telescopic devices (205) and the electric control cradle head (206) so that the scanning device (207) can shoot/scan the ceramic shell (4) to be dried in all directions to obtain the image/scan data of the ceramic shell (4) to be dried.
15. The method for producing a ceramic shell for precision casting according to claim 12, wherein the model structure analysis includes image analysis:
firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of a ceramic shell (4) to be dried;
then, comparing the acquired image data with the outer contour model data, and determining the space orientation of the ceramic shell (4) to be dried in the vacuum drying cavity (1);
and finally, determining the current deep hole position and orientation of the ceramic shell (4) to be dried according to the space orientation of the ceramic shell (4) to be dried, and outputting depth data corresponding to the deep hole position, orientation and deep hole of the ceramic shell (4) to be dried.
16. The method for producing a ceramic shell for precision casting according to claim 12, wherein the scanning device (207) further comprises: a scanning distance measuring device (2073); the scanning distance measuring device (2073) is used for measuring the distance between the ceramic shell (4) to be dried and the scanning device (207) in real time;
The model structure analysis includes:
step 1.1, scanning a ranging device (2073) to perform omnibearing scanning on the surface n of the ceramic shell (4) to be dried according to a preset line to obtain a ranging data set Gn of all scanning points of the surface n relative to the scanning ranging device (2073);
step 1.2, connecting the tail end points of the ranging data set Gn to obtain a digital surface m of the surface n of the ceramic shell (4) to be dried;
step 1.3, carrying out graphic analysis on a digital surface m of the ceramic shell (4) to be dried by combining image data, and determining a basic surface, a convex surface and a concave surface of the digital surface m;
step 1.4, calculating a difference Cmk-b of each ranging point in the groove surface relative to each ranging point of the adjacent basic surface of the groove, wherein mk is a groove with a number k on the digital surface m, and b is an additional number of the ranging point in the groove mk;
step 1.5, taking Cmk-b > K2 as a deep hole and Cmk-b > K3 as a through hole; wherein K2 is a preset deep hole judgment threshold value, and K3 is a model width or a model length or a model height corresponding to the surface n of the ceramic shell (4) to be dried;
step 1.6, counting the positions Wmc of all deep holes on the digital surface m of the ceramic shell (4) to be dried and the depth Hmc corresponding to each deep hole, wherein c is the natural number of the deep holes on the digital surface m;
step 1.7, repeating the steps 1.1 to 1.6 to the positions Wmc and the depths Hmc of deep holes on the surface of the ceramic shell (4) to be dried, which can be scanned, and determining the orientation Xmc of the deep holes according to the surface n of the deep holes;
And step 1.8, outputting data of positions Wmc, depths Hmc and orientations Xmc of deep holes on the whole surface of the ceramic shell (4) to be dried.
17. The method of producing a ceramic shell for precision casting according to claim 16, wherein the method of obtaining the basic face, the convex face and the concave face in step 1.3 comprises:
step 1.3.1, obtaining image data corresponding to the digital surface m of the ceramic shell (4) to be dried, and obtaining an image surface R by splicing the image data;
step 1.3.2, carrying out element recognition on the image surface R to obtain element areas rn-m on the image surface R, wherein rn is the sequence number of the element areas in the digital surface m;
step 1.3.3, adjusting the digital surface m to the same orientation and similar size as the image surface R;
step 1.3.4, taking an element region rc-m with the largest continuous area as a basic surface, wherein the rc-m belongs to rn-m;
step 1.3.5, obtaining ranging point data of each non-basic surface element area, wherein element area ranging points with the distance larger than that of adjacent basic surface ranging points are groove points, and element area ranging points with the distance smaller than that of adjacent basic surface ranging points are raised points;
step 1.3.6, using the element area as a boundary, connecting adjacent groove points and protruding points to form a groove surface and a protruding surface.
18. The method for manufacturing a ceramic shell for precision casting according to claim 16, wherein the electronic control cradle head (206) comprises: a fixed table (2061) fixed with the electric control telescopic device (205), and a rotating table (2062) which is rotationally connected with the fixed table (2061) and rotates along a vertical shaft relative to the fixed table (2061); the rotating table (2062) is rotationally connected with the fixed end of the second electric control telescopic device (2064) through a speed reducer (2063), and the speed reducer (2063) controls the second electric control telescopic device (2064) to rotate along the horizontal shaft; the telescopic end of the second electric control telescopic device (2064) is fixed with the scanning device (207).
19. The method for producing a ceramic shell for precision casting according to claim 18, wherein the model structure analysis further comprises:
step 2.1, controlling the scanning distance measuring device (2073) to move to the deep hole position according to the deep hole position;
step 2.2, acquiring a plurality of deep hole depth measurement data by adjusting the orientation of the relative deep holes of the scanning distance measuring device (2073);
and 2.3, correcting the depth data Hm-c of the original deep hole by using the depth measurement data with the deepest depth to obtain corrected data Hm-c'.
20. The method for producing a ceramic shell for precision casting according to claim 12, wherein the scanning device (207) further comprises: an infrared temperature measuring device (2074); the control system includes: the drying process analysis module acquires the measurement quantity of the infrared temperature measuring device (2074) to carry out drying process analysis so as to judge whether the ceramic shell (4) to be dried is dried or not;
The drying process analysis includes: measuring the temperature T in the deep hole at regular time or continuously; making a curve Qv of the deep hole temperature Tv-the drying time t, and when all the Qv have curve sections conforming to a preset curve rule, indicating that the drying of the ceramic shell (4) to be dried is completed; wherein v is the natural number of all deep holes of the ceramic shell (4) to be dried.
21. The method for preparing a ceramic shell for precision casting according to claim 20, wherein the predetermined curve rule comprises: the temperature T in the deep hole gradually decreases to a temperature T2 along with the drying time from the initial drying temperature T1, then gradually increases to a drying environment temperature T3 along with the drying time, and when the temperature T of the deep hole of the ceramic shell (4) to be dried is subjected to T1-T2-T3 and the drying environment temperature T3 is maintained for a preset time U, the drying is judged to be finished; the initial drying temperature T1 is 22-26 ℃, the temperature T2 is 5-7 ℃ lower than the temperature T1, and the ambient drying temperature T3 is 24+/-1 ℃.
22. The method for producing ceramic shells for precision casting according to claim 21, wherein when the number of ceramic shells to be dried (4) in the same batch is plural, the temperatures of the deep holes of the ceramic shells to be dried (4) are detected one by one, and when more than L% of the ceramic shells to be dried (4) are dried, the completion of the drying of the ceramic shells to be dried (4) in the whole batch is judged; the ratio of L% = (Lg-d)/(L0-d) is 100%, wherein Lg-d is the number of ceramic shells (4) to be dried after the completion of the drying of the batch d, and L0-d is the number of all ceramic shells (4) to be dried in the batch d; wherein the value of L% is as follows: 100 percent or more, L percent or more, E percent or more; wherein E is a preset threshold value of the lowest drying completion percentage of all ceramic shells (4) to be dried in the batch d.
23. The method of preparing a ceramic shell for precision casting according to claim 12, wherein the fan set control analysis comprises:
for all the fan groups p with deep holes on the surfaces of the facing ceramic shells (4) to be dried, the following method is adopted:
step 3.1, obtaining the total number D0 of all deep holes of the ceramic shell (4) to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell (4) to be dried of the facing fan group p; the P is a fan set number arranged on different sides in the vacuum drying cavity (1);
step 3.2 calculating k S-p percent=dp/D0 x 100%, said k S-p % is the control parameter of the fan group p;
step 3.3 repeating steps 3.1 to 3.2 until k for all fan sets is obtained S-p ％；
For all the fan groups p facing the surface of the ceramic shell (4) to be dried without deep holes, the following method is adopted:
calculating kF-p% = [ 1-D0/(D0+1) ], wherein kF-p% is a control parameter of the fan group p;
the fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
24. The method of preparing a ceramic shell for precision casting according to claim 12, wherein the fan set control analysis comprises:
For all the fan groups p with deep holes on the surfaces of the facing ceramic shells (4) to be dried, the following method is adopted:
step 4.1, obtaining the total number D0 of all deep holes of the ceramic shell (4) to be dried, and obtaining the total number Dp of all deep holes on the surface of the ceramic shell (4) to be dried of the facing fan group p; the P is a fan set number arranged on different sides in the vacuum drying cavity (1);
step 4.2 obtaining k from the control parameter database according to the number of D0 and Dp S-p The%; the k is S-p % is the control parameter of the fan group p;
step 4.3 repeat steps 4.1 to 4.2 to obtain k for all the fan sets S-p ％；
For all the fan groups p facing the surface of the ceramic shell (4) to be dried without deep holes, the following method is adopted:
obtaining kF-p% from a control parameter database according to the total number D0 of all deep holes of the ceramic shell (4) to be dried; the kF-p% is a control parameter of the fan group p;
the fan set control module sends the obtained kS-p% and kF-p% of all the fan sets to the corresponding fan set p so as to control the fan set p to run at the fully loaded kS-p% or kF-p%.
25. The method for producing ceramic shells for precision casting according to claim 24, wherein k is entered into a control parameter database S-p The% and kF-p% method includes:
Step 5.1, simulating the same fan set position and orientation as the target vacuum drying cavity (1) in simulation equipment;
step 5.2, presetting deep hole distribution conditions of different ceramic shells (4) to be dried for drying training, and determining control parameters k of each fan set p corresponding to optimal drying time under each deep hole distribution condition when the fan set p is relatively fully loaded S-p % and kF-p%; the deep hole distribution condition comprises: deep hole orientation and number; the optimal drying time is the shortest time for the deep holes and the surface layers of each surface of the ceramic shell (4) to be dried synchronously;
step 5.3 repeating the step 5.2 until training of deep hole distribution under normal conditions is completed, and constructing D0-Dp-k S-p And (3) a deep hole-control parameter relation group of%kF-p% and storing the deep hole-control parameter relation group into a control parameter database.
26. The method for producing a ceramic shell for precision casting according to any one of claims 23 or 24, wherein at least two fans are arranged in the fan group; and the fan group control module synchronously controls or independently controls the fans in each group of fan groups.
27. The method of preparing a ceramic shell for precision casting according to claim 26, wherein the fan set control analysis further comprises:
Step 6.1, constructing a three-dimensional coordinate system based on a scanning starting point preset by a scanning device (207);
step 6.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device (207), and marking the three-dimensional coordinate point on the deep hole position, the direction and the depth of the obtained ceramic shell (4) to be dried in the model structure analysis process;
step 6.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fan in the fan set p;
step 6.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area;
step 6.5 calculate kup-e% = (Dup-e/Dup) ×k S-p ％；
The fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load; for the fan corresponding to Dup-e=0, it is operated at the lowest power.
28. The method of preparing a ceramic shell for precision casting according to claim 26, wherein the fan set control analysis comprises:
step 7.1, constructing a three-dimensional coordinate system based on a scanning starting point preset by a scanning device (207);
step 7.2, recording a space three-dimensional coordinate point in the displacement process of the scanning device (207), and marking the three-dimensional coordinate point on the deep hole position, the direction and the depth of the obtained ceramic shell (4) to be dried in the model structure analysis process;
Step 7.3, acquiring a coordinate system range Up-e covered by the blowing direction of each fan in the fan set p, wherein e is the natural number of the fan in the fan set p;
step 7.4, counting the number Dup-e of deep holes in the Up-e coverage area and the number Dup of deep holes in the whole fan group p coverage area;
step 7.5, acquiring kup-e% of corresponding fans from a control parameter database according to Dup and Dup-e, wherein kup-e% are control parameters of fans with the number e in the fan group p;
the fan set control module sends kup-e% of each fan in the obtained fan set p to the corresponding fan so as to control the corresponding fan to run at kup-e% of full load.
29. The method for preparing ceramic shells for precision casting according to claim 28, wherein the method for entering kup-e% into the control parameter database comprises:
step 8.1, simulating the same fan set position and orientation as the target vacuum drying cavity (1) in simulation equipment;
step 8.2, presetting deep hole distribution conditions of different ceramic shells (4) to be dried for drying training, and determining the running proportion kup-e% of each fan in each fan group p corresponding to the optimal drying time under the deep hole distribution conditions when the fans are fully loaded; the deep hole distribution condition comprises: deep hole orientation and number; the optimal drying time is the shortest time for the deep holes and the surface layers of each surface of the ceramic shell (4) to be dried synchronously;
And 8.3, repeating the step 8.2 to the conventional deep hole distribution condition training, constructing a deep hole-control parameter relation group of Dup-e-kup-e%, and storing the deep hole-control parameter relation group in a control parameter database.
30. The method of producing a ceramic shell for precision casting according to any one of claims 24 or 28, wherein the vacuum flash drying system comprises: the system comprises a first data transmission module, a local database module and a remote system module;
the first data transmission module is in signal connection with the remote system module through a signal line connection or a wireless network connection mode;
the local database module is used as a control parameter database for storing related deep hole-control parameter relation groups;
the remote system module collects deep hole-control parameter relation groups of all vacuum quick drying systems through the first data transmission module, and selects optimal control parameters from the same deep hole relation to obtain the optimal deep hole-control parameter relation groups under the deep hole relation; synchronizing the optimal deep hole-control parameter relation group to a local database module of each vacuum quick drying system through a first data transmission module based on authorization permission and/or instructions and/or an automatic synchronization mode;
When the vacuum quick drying system calls the deep hole-control parameter relation group in the local database module, if the optimal deep hole-control parameter relation group exists, the optimal deep hole-control parameter relation group is preferentially called.
31. The method of preparing a ceramic shell for precision casting according to claim 30, wherein the vacuum flash drying system comprises a second data transmission module and a remote system;
the first data transmission module is in signal connection with the remote system module through a signal line connection or a wireless network connection mode;
the local database module is used as a control parameter database for storing related deep hole-control parameter relation groups and operation result data;
the remote system module collects deep hole-control parameter relation groups and operation result data of each vacuum quick drying system through the first data transmission module, and selects a deep hole-control parameter relation group corresponding to the optimal operation result from the same deep hole relation; based on authorization permission and/or instructions and/or an automatic synchronization mode, the deep hole-control parameter relation group corresponding to the optimal operation result is concentrated through a remote system and then is synchronized into the local database module of each vacuum quick drying system through a first data transmission module, or is directly synchronized into the local database module of each vacuum quick drying system through the first data transmission module;
When the vacuum quick drying system calls the deep hole-control parameter relation group in the local database module, if a new optimal deep hole-control parameter relation group exists, the new optimal deep hole-control parameter relation group is preferentially called.
32. The method for producing a ceramic shell for precision casting according to claim 7, wherein the drying rack (3) comprises: the ceramic shell hanging frame (304) is used for hanging the ceramic shell (4) to be dried; a plurality of hooking grooves (305) are formed in the ceramic shell hanging frame (304); the ceramic shell (4) to be dried is hooked at the hooking groove (305) through the lifting hook (11); a hanging bracket support plate (302) is fixed at the bottom of the ceramic shell hanging bracket (304); the bottom of the hanger support plate (302) is provided with a plurality of rollers (303) which can slide along the guide rail (301); the guide rail (301) is fixed on the bottom surface of the vacuum drying cavity (1).
33. The method for manufacturing a ceramic shell for precision casting according to claim 32, wherein a limit block is arranged on the guide rail (301) at a side far away from the opening and closing door of the vacuum drying chamber (1).
34. The method for producing a ceramic shell for precision casting according to claim 12, wherein the scanning device (207) comprises: a thermal imager (2072); the method for enabling the drying time of all parts of the whole ceramic shell to be dried to be consistent comprises the following steps:
Step 9.1, carrying out real-time thermal imaging shooting on the ceramic shell (4) to be dried along with a scanning device (207) by a thermal imager (2072) in the drying process of the ceramic shell (4) to be dried, and sending the shooting to a control system;
and 9.2, the control system judges whether an area T with the temperature difference exceeding a preset temperature difference threshold exists according to the thermal imaging graph when the drying time exceeds the preset first drying time according to the heat distribution condition in the thermal imaging graph, and if the area T exists, the control system judges and operates as follows:
when the temperature of the low-temperature area of the area T is lower than a preset low-temperature threshold value, reducing the operation power of the fan set corresponding to the area T;
when the temperature of the high-temperature area of the area T is higher than a preset high-temperature threshold value, the operation power of the area T corresponding to the fan set is increased;
when the existence time of the area T exceeds a preset time threshold, the temperature of a low-temperature area of the area T is higher than a preset low-temperature threshold, and the temperature of a high-temperature area of the area T is lower than a preset high-temperature threshold, the operation power of the area T corresponding to the fan set is increased.
35. The method of claim 34, wherein the predetermined low temperature threshold is 12-15 ℃, the predetermined high temperature threshold is 26-28 ℃, the predetermined first drying time is 1-3 minutes, and the predetermined time threshold is 30-60 seconds.
36. The method for producing a ceramic shell for precision casting according to claim 1, wherein the method for vacuum rapid drying treatment comprises:
drying the surface layer: firstly, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 750-720 mmHg within 5 seconds; then restoring the vacuum degree of the ceramic shell environment to be dried from 750-720 mmHg to normal pressure within 5 seconds; the above process is circulated until the surface layer is dried;
when the transition layer is dried: firstly, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 720-680 mmHg within 7 seconds; then the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 7 seconds from 720-680 mmHg; repeating the above process circularly until the transition layer is dried;
when drying the support layer, the method comprises the following steps:
step 10.1, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 260-20 mmHg within 30 seconds;
step 10.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes;
step 10.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to be restored to normal pressure within 90 seconds;
step 10.4, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 260-20 mmHg within 30 seconds;
Step 10.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to be restored to normal pressure within 90 seconds;
step 10.6, repeating the step 10.4 and the step 10.5 until the support layer is dried;
when the sealing layer is dried: firstly, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 120-90 mmHg within 40 seconds; then, the vacuum degree of the ceramic shell environment to be dried is restored to normal pressure within 120 seconds; and (5) repeating the process circularly until the sealing layer is dried.
37. The method for preparing a ceramic shell for precision casting according to claim 36, wherein the supporting layer is provided with at least three layers in sequence from the transition layer to the sealing layer, wherein:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 11.1, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 260-220 mmHg within 30 seconds;
step 11.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes;
step 11.3, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 40 seconds;
step 11.4, reducing the vacuum degree of the ceramic shell environment to be dried from normal pressure to 260-220 mmHg within 30 seconds;
step 11.5, enabling the vacuum degree of the ceramic shell environment to be dried to be restored to normal pressure within 40 seconds;
Step 11.6, repeating the step 11.4 and the step 11.5 until the first layer of the supporting layer is dried;
the inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 12.1, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 200-150 mmHg within 30 seconds;
step 12.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes;
step 12.3, enabling the vacuum degree of the ceramic shell environment to be dried to be restored to normal pressure within 60 seconds;
step 12.4, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 200-150 mmHg within 30 seconds;
step 12.5, enabling the vacuum degree of the ceramic shell environment to be dried to be restored to normal pressure within 60 seconds;
step 12.6, repeating the step 12.4 and the step 12.5 until the second layer of the supporting layer is dried;
the inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 13.1, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 80-20 mmHg within 30 seconds;
step 13.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes;
step 13.3, enabling the vacuum degree of the environment of the ceramic shell to be dried to be restored to normal pressure within 90 seconds;
Step 13.4, reducing the vacuum degree of the environment of the ceramic shell to be dried from normal pressure to 80-20 mmHg within 30 seconds;
step 13.5, enabling the vacuum degree of the environment of the ceramic shell to be dried to be restored to normal pressure within 90 seconds;
step 13.6, repeating the step 13.4 and the step 13.5 until the third layer of the supporting layer is dried;
and the inner surface of the closed layer is attached to the outer surface of the third layer of the supporting layer.
38. The method of preparing a ceramic shell for precision casting according to any one of claims 36 or 37, wherein the vacuum flash drying system comprises: the vacuum drying device comprises a vacuum drying cavity (1), a vacuum pump (8) and a control system; the vacuum pump (8) performs vacuumizing treatment on the vacuum drying cavity (1); the vacuum pump (8) is communicated with the vacuum drying cavity (1) through a first connecting pipe, and a first electric control switch valve (10) is arranged on the first connecting pipe; the vacuum drying cavity (1) is communicated with an air pipe (106), and a second electric control valve (107) is arranged on the air pipe (106);
the ceramic shell (4) to be dried is placed in a vacuum drying cavity (1) for vacuum rapid drying treatment;
the control system controls the opening and closing of the vacuum pump (8), the first electric control switch valve (10) and the second electric control valve (107) to realize the method steps of the vacuum quick drying treatment.
39. The method of preparing a ceramic shell for precision casting according to claim 38, wherein the vacuum flash drying system further comprises: a vacuum tank (5); one end of the vacuum tank (5) is communicated with the vacuum pump (8) through a second connecting pipe, and a third electric control valve (9) is arranged on the second connecting pipe; the other end of the vacuum tank (5) is communicated with the vacuum drying cavity (1) through a third connecting pipe (7), and a fourth electric control valve (6) is arranged on the third connecting pipe (7).
40. The method for producing a ceramic shell for precision casting according to claim 39, further comprising an instantaneous depressurization operation when vacuum drying is performed for the supporting layer and the closing layer; the transient step-down operation includes:
firstly, before depressurization, closing a fourth electric control valve (6), and pumping the vacuum tank (5) to a low vacuum state in advance;
then, when the pressure is reduced, a fourth electric control valve (6) is opened, so that the vacuum drying cavity (1) is communicated with the vacuum tank (5) and is instantaneously reduced to the balance low pressure within 0.5 seconds;
finally, the vacuum pump (8) simultaneously extracts the gas phase components in the vacuum tank (5) and the vacuum drying cavity (1), so that after the vacuum degree in the vacuum drying cavity (1) accords with a preset target, the fourth electric control valve (6) and the first electric control switch valve (10) are closed, and meanwhile, the vacuum pump (8) continuously extracts the gas phase components in the vacuum tank (5) until the vacuum tank (5) is in a low vacuum state.
41. The method of manufacturing a ceramic shell for precision casting according to claim 40, wherein the support layer comprises at least three layers in sequence from the transition layer to the closing layer, wherein:
the first inner surface of the supporting layer is attached to the outer surface of the transition layer, and when the first layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
14.1, performing instant depressurization, and reducing the environmental vacuum degree of the ceramic shell to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
step 14.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank (5);
step 14.3, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank (5);
14.4, performing instant depressurization, and reducing the environmental vacuum degree of the ceramic shell to be dried from instant equilibrium low pressure to 260-220 mmHg within 10 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
step 14.5, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 40 seconds, and continuously vacuumizing the vacuum tank (5);
step 14.6, repeating the step 14.4 and the step 14.5 until the first layer of the supporting layer is dried;
The inner surface of the second layer of the supporting layer is attached to the outer surface of the first layer of the supporting layer, and when the second layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
15.1, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
15.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank (5);
15.3, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing a vacuum tank (5);
15.4, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 200-150 mmHg within 15 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
15.5, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 60 seconds, and continuously vacuumizing a vacuum tank (5);
step 15.6, repeating the step 15.4 and the step 15.5 until the second layer of the supporting layer is dried;
the inner surface of the third layer of the supporting layer is attached to the outer surface of the second layer of the supporting layer, and when the third layer of the supporting layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 16.1, performing instant depressurization, and reducing the environmental vacuum degree of the ceramic shell to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
Step 16.2, maintaining the vacuum degree of the ceramic shell environment to be dried in a negative pressure state for 4-6 minutes, and continuously vacuumizing the vacuum tank (5);
step 16.3, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 90 seconds, and continuously vacuumizing the vacuum tank (5);
step 16.4, performing instant depressurization, and reducing the environmental vacuum degree of the ceramic shell to be dried from instant equilibrium low pressure to 80-20 mmHg within 25 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
step 16.5, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 90 seconds, and continuously vacuumizing the vacuum tank (5);
step 16.6, repeating the step 16.4 and the step 16.5 until the third layer of the supporting layer is dried;
the inner surface of the sealing layer is attached to the outer surface of the third layer of the supporting layer, and when the sealing layer is subjected to vacuum rapid drying treatment, the method comprises the following steps:
step 17.1, performing instant depressurization, and reducing the vacuum degree of the environment of the ceramic shell to be dried from instant equilibrium low pressure to 260-220 mmHg within 35 seconds, and simultaneously maintaining the vacuum pumping of the vacuum tank (5);
step 17.2, enabling the vacuum degree of the ceramic shell environment to be dried to return to normal pressure within 120 seconds, and continuously vacuumizing the vacuum tank (5);
step 17.3 steps 17.1 and 17.2 are repeated until the encapsulation layer is dried.
42. The method for producing ceramic shells for precision casting according to claim 1, wherein the ceramic shells to be dried are placed in a vacuum rapid drying system, and then left to stand for 30 to 120 seconds, and then subjected to the vacuum rapid drying treatment.
43. The method of manufacturing a ceramic shell for precision casting according to claim 42, wherein the vacuum flash drying system performs low-power drying of the ceramic shell to be dried during the standing.
44. The method for producing a ceramic shell for precision casting according to claim 2, wherein a defoaming agent is added to the surface layer in an amount of 0.1 to 0.5% by mass of the ceramic shell sol.
45. The method for producing a ceramic shell for precision casting according to claim 2, wherein a foaming agent is added to the supporting layer in an amount of 0.5 to 1% by mass of the ceramic shell sol.
46. The method for preparing the ceramic shell for precision casting according to claim 2, wherein the mass concentration of silicon dioxide in the mixed system of the ceramic shell sol, powder and water is 22-25%.
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| CN105903909A (en) * | 2016-06-12 | 2016-08-31 | 蔡政达 | Fast drying method and device for ceramic shell |
| CN106734879A (en) * | 2016-12-12 | 2017-05-31 | 重庆理工大学 | A kind of lost foam casting moulding process of waste incineration reciprocating grate bar |
| CN206732065U (en) * | 2017-04-28 | 2017-12-12 | 连云港源钰金属制品有限公司 | A kind of lost wax casting shell mould drying system |
| CN110479970A (en) * | 2019-09-29 | 2019-11-22 | 洛阳金峰机电装备有限公司 | A kind of silica solution formwork quick-drying dedusting environment control unit |
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| CN112620584A (en) * | 2020-12-11 | 2021-04-09 | 无锡卡仕精密科技有限公司 | Vacuum slurry-bonding silica sol shell-making process method for medical implant casting |
| CN115608928A (en) * | 2022-10-28 | 2023-01-17 | 中国航发沈阳黎明航空发动机有限责任公司 | High-air-permeability directional/single crystal blade ceramic shell and preparation method thereof |
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| CN106734879A (en) * | 2016-12-12 | 2017-05-31 | 重庆理工大学 | A kind of lost foam casting moulding process of waste incineration reciprocating grate bar |
| CN206732065U (en) * | 2017-04-28 | 2017-12-12 | 连云港源钰金属制品有限公司 | A kind of lost wax casting shell mould drying system |
| CN110479970A (en) * | 2019-09-29 | 2019-11-22 | 洛阳金峰机电装备有限公司 | A kind of silica solution formwork quick-drying dedusting environment control unit |
| CN112045151A (en) * | 2020-09-23 | 2020-12-08 | 贵州安吉航空精密铸造有限责任公司 | Drying device for casting shell |
| CN112620584A (en) * | 2020-12-11 | 2021-04-09 | 无锡卡仕精密科技有限公司 | Vacuum slurry-bonding silica sol shell-making process method for medical implant casting |
| CN218532723U (en) * | 2022-10-17 | 2023-02-28 | 横峰县江鑫机械科技有限公司 | A directional air-dry device of wax matrix for preparation of tiny through-hole pump body shell |
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