CN110962301A

CN110962301A - Bumper injection mold and warpage rate control method thereof

Info

Publication number: CN110962301A
Application number: CN201911169721.4A
Authority: CN
Inventors: 黄可; 刘江; 卜凡
Original assignee: Changzhou Vocational Institute of Mechatronic Technology
Current assignee: Sicguo Chengdu Intellectual Property Operation Co ltd; Zhongxing Xingda Auto Accessories Co ltd
Priority date: 2019-11-26
Filing date: 2019-11-26
Publication date: 2020-04-07
Anticipated expiration: 2039-11-26
Also published as: CN110962301B

Abstract

The invention discloses a bumper injection mold and a warpage rate control method thereof, wherein the bumper injection mold comprises a fixed mold plate, a fixed mold, a movable mold plate, a sprue channel, an ejector rod and an inclined ejector, wherein a product accommodating cavity is formed between the fixed mold and the movable mold; the middle part of the product accommodating cavity protrudes towards the fixed die, reverse buckling parts are formed on two sides of the product accommodating cavity, the ejector rod is suitable for jacking a product towards the fixed die, and the inclined tops are symmetrically arranged at the reverse buckling parts on two sides of the movable die; one end of the inclined top is fixedly connected with the movable template, and the other end of the inclined top is suitable for reciprocating along the direction of the inclination angle of the edge of the back-off part. The invention can avoid the interference phenomenon between the inclined top and the inverted buckle part when the bumper is ejected out, and effectively reduce the deformation of the product. And the problem that the preset parameters of the mold flow analysis software are inconsistent with the actual injection molding parameters can be effectively solved, the analysis accuracy is improved, and the warping rate of the product is greatly reduced.

Description

Bumper injection mold and warpage rate control method thereof

Technical Field

The invention relates to the technical field of mold design, in particular to a bumper injection mold and a warpage rate control method of the bumper injection mold.

Background

Bumper mould, the precision is high, and total price is big, at the mould design initial stage, mostly can carry out the mould flow analysis, nevertheless in the implementation, often do not carry out mould design manufacturing according to the preset condition (some condition can't accurately transmit) of mould flow analysis, has formed that mould flow analysis only stops at the theoretical aspect. In order to break through the situation, the idea of mold flow analysis software preset parameters and whole-process feedback is provided, the mold is designed, the injection molding parameters of the mold can be monitored in the whole process, the original numerical values are recorded, the size change rule of the product is compared, and effective guarantee is provided for obtaining the product with qualified quality. In the mold testing stage, once the size of the product fluctuates, the size of the product is regulated by regulating injection molding parameters, the injection molding pressure is changed after the product enters a mold, the melt temperature also fluctuates after passing through a hot runner, and the real value in the filling stage cannot be directly reflected, so that the warping amount of the product cannot be further optimized. How to realize the real-time display of the pressure/temperature of the die cavity and further optimize the warping amount of the product becomes a problem to be solved urgently. In addition, in the prior art, due to the fact that the reverse buckling part of the automobile bumper is adhered with the inclined top during ejection, all parts of the automobile bumper cannot be ejected out simultaneously, the automobile bumper is damaged due to unbalanced ejection of the automobile bumper, large deformation and even cracks occur, and therefore a device capable of stably ejecting the automobile bumper is needed.

In the prior art, the application number is CN106584031A, and the name is MOLDFLOW-based automobile box part injection mold manufacturing method, the modeling and deformation analysis of plastic parts are disclosed; selecting materials of the mold and formulating a reasonable mold heat treatment scheme to manufacture the automobile box part injection mold; tool deformation compensation; and (5) visually detecting the machining error compensation.

In the prior art, the application number is CN101430720A, and the name is 'analytical method for in-mold decoration injection molding', the analysis of molding engineering is disclosed; processing a grid interface; and an injection engineering analysis part which is merged into the film grid and the forming mold grid, sets forming parameters for engineering analysis to obtain an embedded film grid and an injected resin grid, and is merged into the embedded film grid and the injected resin grid, and sets the injection parameters for mold flow analysis to obtain in-mold decoration injection molding analysis information.

In the prior art, the application number is CN108549764A, and the name is automotive instrument structure optimization method based on MOLDFLOW analysis, and the method is disclosed in that a CATIA software is used for establishing a model for an automotive instrument structure, the model is led into a CADdocctor for diagnosis and then is repaired, and the repaired model is led into the CADdocctor for diagnosis; and carrying out double-layer grid division and grid statistics, carrying out grid repair according to the grid division result, setting analysis content in a filling dialog box, selecting materials and marks in a material dialog box, setting a pouring system, clicking to start analysis, generating an analysis report, modifying the model in the CATIA according to the analysis report, and diagnosing the modified model again until a defect-free automobile instrument structure model is obtained.

In the prior art, the application number is CN107972243A, named as SOM neural network-based injection molding process optimization method and injection molding process, discloses an SOM neural network-based injection molding process optimization method, which comprises the following steps of establishing a mold flow analysis model of an injection molding product; simulating and simulating the injection molding process parameters of the analog flow analysis model by using CAE software to obtain the injection molding process parameter types causing injection molding defects of injection molding products; acquiring injection molding process parameter types by utilizing an orthogonal test and CAE software based on injection molding process parameters, wherein the injection molding process parameter influence weights and first optimized injection molding process parameters cause injection molding defects of injection molded products, and the injection molding process parameter influence weights and the first optimized injection molding process parameters are based on the injection molding process parameters; and obtaining final optimized injection molding process parameters by using the SOM neural network.

In the prior art, the application number CN106250648A entitled "a structure analysis method for glass fiber reinforced material based on ABAQUS and MOLDFLOW joint simulation" discloses a structure analysis method for glass fiber reinforced material based on ABAQUS and MOLDFLOW joint simulation, which directly imports the fiber distribution and direction information calculated by the mold flow software MOLDFLOW into the grid information of ABAQUS through a running script file. As long as the geometric model is kept consistent with the geometric model during the module flow analysis, researchers can utilize the geometric model to divide the grids again according to own requirements, and after the fiber direction is mapped, the researchers can assign material attributes according to test data. After the definition of the model boundary condition application and the field variable and time output is completed in ABAQUS, JOB can be submitted for calculation. The method combines ABAQUS software and MOLDFLOW software to perform modular flow analysis and structural analysis, and can be suitable for complex models and complex working conditions.

In the prior art, the application number CN107506507A, entitled "injection molding finite element simulation method based on MOLDFLOW symmetric structure" discloses an injection molding finite element simulation method based on MOLDFLOW symmetric structure, which divides an injection molding part digifax of symmetric structure from its central axis into two symmetric parts, only one of which is reserved, and a symmetric plane is formed at the divided part of the part; importing a digital model of the part into an MOLDFLOW, and carrying out finite element meshing on the part; deleting the grids on the symmetrical plane after optimizing the quality of the grids; taking the symmetrical plane as a mirror image plane and the nodes on the symmetrical plane as reference points, and then copying all the parts to generate a symmetrical grid of the other half part; combining free edge nodes at the two symmetrical surfaces to obtain a grid with a whole symmetrical structure; and setting parameters for the whole symmetrical structure grid and submitting for analysis.

In summary, the prior art does not provide a solution to the problem of real-time display of the cavity pressure/temperature, so as to further optimize the warpage amount of the product, and also does not provide a solution to the problem of the product ejection interference caused by the pitched roof.

Disclosure of Invention

The invention provides a bumper injection mold and a product warping rate control method, aiming at solving the problems that in the prior art, when an automobile bumper is ejected, all parts of the automobile bumper cannot be ejected simultaneously due to the fact that the back-off part of the automobile bumper is adhered with an inclined top, the automobile bumper is ejected out unevenly, and the automobile bumper is damaged.

The term "article" as used herein refers to a bumper made using the mold of the present application.

The invention provides a bumper injection mold, which comprises a fixed mold plate, a fixed mold, a movable mold plate, a sprue channel, an ejector rod and an inclined top, wherein a product containing cavity is formed between the fixed mold plate and the movable mold plate, and the sprue channel extends into the product containing cavity from the surface of the fixed mold plate; the middle part of the product accommodating cavity protrudes towards the fixed die, reverse buckling parts are formed on two sides of the product accommodating cavity, the ejector rod is suitable for jacking a product towards the fixed die, and the inclined tops are symmetrically arranged at the reverse buckling parts on two sides of the movable die; one end of the inclined top is fixedly connected with the movable template, and the other end of the inclined top is suitable for reciprocating along the direction of the inclination angle of the edge of the back-off part.

After the product is manufactured, the two sides of the product are provided with the inverted buckle parts, the inverted buckle parts and the inclined top have a conflict structure along the vertical direction, if the product is directly and vertically taken out, the product can collide with the inclined top, and because the inverted buckle parts are formed along with the mold structure, the edge inclination angle of the inverted buckle parts is the same as that of the inclined top, only one end of the inclined top, which is close to the product, needs to move away from the product along the edge inclination direction of the inverted buckle parts before the product is taken out until the inclined top is separated from the inverted buckle parts, and then the product is ejected out for demolding.

Further, the lifter comprises: the fixed seat is fixed on the movable template; the guide rail, the guide rail connect in the one end of fixing base, the pneumatic cylinder, the stiff end of pneumatic cylinder articulate in the other end of fixing base, the expansion end of pneumatic cylinder with guide rail sliding connection, just the pneumatic cylinder is suitable for to follow reciprocating motion is made to the axis direction of guide rail. And the inclined top insert is positioned at the top of the movable end of the hydraulic cylinder and is suitable for limiting the reverse buckling part of the product.

Furthermore, a plurality of waterway channels are arranged in the movable mold in a laminated manner, the waterway channels are offset along the direction of the inner normal line of the convex surface of the movable mold, each layer of water pipes in the waterway channels are arranged in series, and each layer of waterway channel is provided with a water inlet interface and a water outlet interface respectively.

Furthermore, a hot runner system communicated with the product containing cavity is arranged in the fixed die and comprises a splitter plate positioned below the sprue, a plurality of hot nozzle parts communicated with the splitter plate and the product containing cavity, and a temperature control box for controlling the temperature of the hot runner system.

Preferably, the hot nozzle part comprises a linear hot nozzle connected with the upper part of the product cavity and a universal hot nozzle connected with the back-off part of the product cavity.

The invention also provides a method for controlling the warping rate of a product, which is characterized in that the method uses the bumper injection mold, and the method comprises the following steps: the method comprises the following steps: in the simulation stage, a three-dimensional graph of the mold is led into mold flow analysis software to be analyzed to obtain the theoretical warping amount of the product under the condition of initial injection molding parameters; step two: in the mold testing stage, a mold provided with a plurality of temperature sensors and mold pressing sensors is placed into an injection molding machine, and the state of the product containing cavity is collected in real time to obtain an actual injection molding parameter value; step three: in the correction stage, replacing the initial injection molding parameters in the first step with the actual injection molding parameters in the second step, and performing the first step again to obtain a new theoretical warping amount; step four: comparing the injection molding parameters of multiple simulation stages with the theoretical warping amount, and optimizing the injection molding parameters through an orthogonal test; step five: and (5) repeating the second step to the fourth step by using the optimized injection molding parameters until the theoretical warping amount reaches an ideal value.

Preferably, the workflow analysis software adopted in the first step is molflow.

Further, the analysis process of the workflow in the step one mainly comprises the following steps:

(1) and (3) carrying out meshing on the three-dimensional model of the mold, wherein the meshing standard is as follows: in the area far away from the gate, the grid size is set to be 1/1500-1/1000 of the longest edge of the product; adopting a refined grid within a range of 15-20 mm close to the gate, wherein the size of the grid is 15% -20% of that of the grid far away from the gate area; (2) setting basic parameters, namely setting the temperature of heat flow in a hot runner; (3) analyzing sequence setting, namely selecting an analysis sequence to cool, fill, maintain pressure and warp in MOLDFLOW software; (4) setting an injection molding process, namely setting the surface temperature of a mold, filling control, melt temperature, speed/pressure switching and pressure maintaining control in sequence; (5) and calculating the warping amount.

Further, the step one, in the mold flow analysis process, further comprises drawing a waterway channel model and then guiding the waterway channel model into mold flow analysis software, and when the mold enters a pressure maintaining stage, introducing industrial pure water into the waterway channel to cool the mold; and after the product is taken out, introducing high-temperature steam into the waterway channel to heat the surface of the mold.

Preferably, the mold heating adopts the way that high-temperature steam is introduced into a waterway channel and is synchronously heated with the resistance wire.

The invention has the beneficial effects that:

(1) the bumper injection mold disclosed by the invention adopts an inclined top structure capable of stretching along a specific direction for the back-off characteristic of a bumper, so that the inclined top can be separated from a back-off part in advance before the bumper is ejected out, the interference phenomenon between the inclined top and the back-off part when the bumper is ejected out is avoided, the deformation of a product is effectively reduced, and the yield of the product is improved.

(2) The inclined top is stretched out and drawn back through the hydraulic cylinder, the moving direction of the hydraulic cylinder is limited through the guide rail, the inclined top insert at the top of the hydraulic cylinder is contacted with the edge of the inverted buckle part, so that the inclination angle at the edge of the inverted buckle part is controlled, the inclined top can be separated from the inverted buckle part only by moving the inclined top along the contact surface of the inclined top insert and the inverted buckle part, and high-quality demoulding work is realized.

(3) According to the method for controlling the warping rate of the product, the actual injection molding parameters are obtained by means of acquiring the state of the mold cavity, the actual injection molding parameters are poured into mold flow software to be calculated to obtain the theoretical warping value, in the reciprocating test, the optimized injection molding parameters are obtained in an orthogonal calculation mode until an ideal product is obtained, the problem that the preset parameters of the mold flow analysis software are inconsistent with the actual injection molding parameters can be effectively solved, the analysis accuracy is improved, and the warping rate of the product is greatly reduced.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a flow chart of a method for controlling warpage of a product according to the present invention;

FIG. 2 is a flow chart of a simulation phase of the warpage control method of a product according to the present invention;

FIG. 3 is a schematic structural view of an injection mold for a bumper according to the present invention;

FIG. 4 is a schematic view of a bumper made by the bumper injection mold of the present invention;

FIG. 5 is a schematic view of a bumper injection mold with temperature sensors and mold pressure sensors installed (stationary mold and stationary mold plate not shown);

FIG. 6 is a schematic view of the installation of a guide square post in the injection mold of the bumper of the present invention;

FIG. 7 is a perspective view of the hot runner system in the bumper injection mold of the present invention;

FIG. 8 is a front view of the hot runner system in the bumper injection mold of the present invention;

FIG. 9 is a perspective view of the waterway channel in the bumper injection mold of the present invention;

FIG. 10 is a side view of the lifter and the bumper structure of the bumper injection mold of the present invention;

fig. 11 is a sectional view taken along line a-a of fig. 10.

In the figure, 1, a fixed die plate, 2, a fixed die, 3, a movable die, 301, a movable die core, 4, a movable die plate, 5, a sprue, 6, a mandril, 7, an inclined top, 701, a fixed seat, 702, a guide rail, 703, a hydraulic cylinder, 704, an inclined top insert, 8, a product containing cavity, 9, a bumper, 10, an inverted buckle part, 11, a water channel, 12, a hot runner system, 1201, a flow distribution plate, 1202, a linear hot nozzle, 1203, a universal hot nozzle, 1204, a temperature control box, 13, a guide square column, 14, a groove, 15, a temperature sensor, 16, a die pressing sensor, 17, a cold and hot water inlet and outlet valve seat, 18 and a cold and hot water switching valve seat.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

As shown in fig. 2, 3 and 7, the bumper injection mold comprises a fixed mold plate 1, a fixed mold 2, a movable mold 3, a movable mold plate 4, a sprue channel, an ejector rod 6 and an inclined ejector 7, wherein the fixed mold plate 1 is positioned above the fixed mold 2, the movable mold plate 4 is positioned below the movable mold 3, the fixed mold 2 and the movable mold 3 are in a cuboid structure after being assembled, a product containing cavity 8 is formed between the fixed mold 2 and the movable mold 3, a movable mold 3 core is arranged at a position, close to the product containing cavity 8, of the movable mold 3, the lower surface curved surface structure of the movable mold 3 core is the same as that of a product, the sprue channel extends into the product containing cavity 8 from the surface of the fixed mold plate 1, and the; the middle part of the product accommodating cavity 8 protrudes towards the fixed die 2, reverse buckling parts 10 are formed on two sides of the product accommodating cavity, the reverse buckling parts 10 are formed by bending the two sides of the product towards the symmetrical axis direction of the product respectively, bowl-shaped structures with inward-bent side walls are formed on the two sides of the product respectively in independent centers, the ejector rod 6 is suitable for jacking the product towards the fixed die 2, namely jacking the product along the vertical direction, the ejector rod 6 is fixed on the movable die plate 4, the air cylinder or the hydraulic cylinder 703 is usually adopted to realize the action of jacking the product, the inclined jacks 7 are symmetrically arranged at the reverse buckling parts 10 on the two sides of the movable die 3, and the symmetrical axes of the two inclined jacks 7 pass through the axis of the sprue 5; one end of the inclined top 7 is fixedly connected with the movable template 4, and the other end is suitable for reciprocating along the direction of the inclination angle of the edge of the back-off part 10.

Specifically, as shown in fig. 9 to 11, the lifter 7 includes: the fixed seat 701 is fixed on the movable template 4; the guide rail 702 is connected to one end of the fixed seat 701, the axis direction of the guide rail 702 is the telescopic direction of the lifter 7, the guide rail 702 and the fixed seat 701 can be fixed by welding, or can be detachably fixed, different guide rail 702 inclination angles can be selected according to different product sizes, the hydraulic cylinder 703 is hinged to the other end of the fixed seat 701, when the inclination angle of the guide rail 702 changes, the axis direction of the hydraulic cylinder 703 can be adjusted accordingly, the movable end of the hydraulic cylinder 703 is connected with the guide rail 702 in a sliding manner, the hydraulic cylinder 703 is suitable for reciprocating along the axis direction of the guide rail 702, and when the hydraulic cylinder 703 does telescopic movement, the movable end of the hydraulic cylinder 703 slides on the guide rail 702. The insert with slanted top 704, which is located on the top of the movable end of the hydraulic cylinder 703, is adapted to define the undercut portion 10 of the product, and as shown in fig. 11, a side wall bent inward is formed on each of the front side and the rear side (i.e., the left side and the right side in fig. 10) of the insert with slanted top 704, and the contact surface of the side wall and the insert with slanted top 704 is an inclined surface parallel to the extending and contracting direction of the slanted top 7.

In the injection molding process, when the mold enters a pressure maintaining stage, a cooling process is needed to condense the molten material in the shortest time, and in addition, when the mold enters an injection molding preparation stage, the mold needs to be rapidly heated to 120 ℃ by using a heating function, for this reason, in another embodiment of the invention, as shown in fig. 9, a plurality of water channels 11 are arranged inside the movable mold 3 in a stacking manner, the water channels 11 are offset along the direction of an inner normal line of the convex surface of the movable mold 3, the convex surface of the movable mold 3 is the top surface of the mold core of the movable mold 3, water pipes in each layer of the water channels 11 are arranged in series, and each layer of the water channels 11 is respectively provided with a water inlet interface and a water outlet. Specifically, a waterway channel 11 is arranged by starting from the inward normal offset of 20-30 mm on the surface of a core of the movable mold 3; the diameter of the water channel 11 is 8-12 mm, if the diameter is too small, the water channel 11 belongs to a slender hole, heat conduction is difficult, and the effect is poor; if the diameter is too large, a laminar state is formed, and the water flow cannot realize a turbulent state; 2-4 times of the diameter of the water pipe is arranged between the water pipes in the waterway channel 11 on the same layer; the depth or height direction is placed in a stacking mode, and water pipes are arranged between the waterway channels 11 on different layers at intervals of 1.5-3 times of the diameter of the water pipes and are rounded into an integer number of layers. If the thickness of the core of the movable mold 3 is insufficient at the lower part of the core of the movable mold 3, and the calculated number of layers cannot be discharged, the water channels 11 are distributed densely at the lower part, and the water channels 11 should be increased at the thicker part of the product. The waterway channels 11 and the waterway channels 11 are connected in a cross way, each layer of waterway channels 11 are connected in a series way, and the parts which are difficult to process are processed by adopting a mode of processing through holes and then repairing plugs.

In this embodiment, the water channel 11 has cooling and heating functions. (1) The cooling function, i.e. the mold entering the dwell phase, is to allow the molten material to solidify in a minimum amount of time. The cooling medium is usually industrial pure water, and different initial water temperatures and flow rates have direct influence on the cooling speed of the die, preferably, the initial water temperature is 15-30 ℃, and the flow rate of the cooling water is 2-6 m/s. (2) The heating function is that the mould adopts a waterway channel 11 to be internally filled with hot steam and a resistance wire to be synchronously heated, and the resistance wire is a heating coil which is inserted between the waterway channels. The heating stage is that the mold product is taken out and is synchronously coated with the release agent. The waterway channel 11 uses compressed air to discharge the medium in the channel in the cooling and heating switching process.

As shown in fig. 1, the water inlet and outlet ports of each layer of waterway 11 are connected to a cold and hot water inlet and outlet valve seat 17 through hoses, so as to facilitate centralized and unified management, and meanwhile, the water inlet and outlet ports of each layer of waterway 11 can be provided with a cold and hot water switching valve seat 18 for switching cooling water and heating steam.

In another embodiment of the present invention, as shown in fig. 7 and 8, a hot runner system 12 is disposed in the fixed mold 2 and is communicated with the product cavity 8, and molten material is transported to each part of the product cavity 8 through the hot runner system 12, which facilitates uniform filling, the hot runner system 12 includes a splitter plate 1201 located below the sprue 5, a plurality of hot nozzle portions communicating the splitter plate 1201 and the product cavity 8, and a temperature control box 1204 for controlling the temperature of the hot runner system 12, and the hot runner system 12 is used to make the molten material in the hot nozzle always in a molten state, so that the die pressure is low, the required mold clamping force is also low, and the requirement on the injection molding machine is reduced. Preferably, the hot nozzle portion comprises a linear hot nozzle 1202 connected to the upper part of the product cavity 8 and a universal hot nozzle 1203 connected to the inverted part 10 of the product cavity 8.

The linear thermal nozzle 1202 adopts a valve needle structure, a cylinder drives a valve needle to move, the minimum scale value of the linear movement of the cylinder is 0.01mm, the precise control of glue melting is realized, and the stroke and the speed of the valve needle, the glue sealing time and the opening time of the valve needle are precisely controlled; the injection molding process is improved, the injection molding period is shortened, the operation and the control are easy, the working environment is improved, the pollution is reduced, and the production is clean. Heating wires are respectively embedded in the upper and lower operating surfaces of the flow distribution plate 1201, and alloy copper is arranged at the top ends of the heating wires to ensure that the ambient temperature of the sprue 5 and the set temperature are controlled within + 1%; a metal fitting (pad) with low thermal conductivity is installed between the flow distribution plate 1201 and the mold to reduce heat loss between the flow distribution plate 1201 and the mold. The adjustable angle of the universal hot nozzle 1203 is 20-70 deg. A PID function is arranged in the temperature control box 1204, so that high-precision temperature control is realized under complex conditions and environments; the temperature is accurately controlled, and the tolerance range can be controlled within +/-0.1 ℃; the system has three operation modes of automatic operation, standby operation, manual operation and the like.

In order to ensure that the fixed die 2 and the movable die 3 move vertically relatively in the die assembly or die disassembly process, a guide structure needs to be arranged, the movable die 3 moves along the direction of the guide structure, the guide structure in the prior art is positioned in the die and is frequently contacted and easily worn as a relatively moving part, and the guide structure in the whole die is most easily worn, so that the whole die is always scrapped in the prior art because the guide structure is internally arranged and is not easily disassembled or can not be disassembled, in yet another specific embodiment of the invention, as shown in fig. 6, the guide structure is a guide square column 13 arranged on the outer side of the movable die 3 and the fixed die 2, grooves 14 which are oppositely arranged are respectively arranged on the side walls of the movable die 3 and the fixed die 2, the guide square column 13 is inserted in the grooves 14 of the movable die 3 and the fixed die 2 in a guiding manner and fixed by screws or rivets, and the installation position is, the mold is only required to be installed on the injection molding machine and replaced in situ, the return-to-factory maintenance of the mold is avoided, the disassembly is convenient, and the service life of the mold is effectively prolonged. The external guide is used for placing, so that the overall dimension of the mold can be effectively reduced, and the injection molding machine can adapt to smaller injection molding machines.

A method for controlling the warping rate of a product, which uses the injection mold for the bumper 9, comprises the following steps: as shown in fig. 1, step one: in the simulation stage, a three-dimensional graph of the mold is led into mold flow analysis software to be analyzed to obtain the theoretical warping amount of the product under the condition of initial injection molding parameters; step two: in the mold testing stage, a mold provided with a plurality of temperature sensors 15 and mold pressing sensors 16 is placed into an injection molding machine (the temperature sensors 15 and the mold pressing sensors 16 are arranged as shown in fig. 5), and the state of the product cavity 8 is collected in real time to obtain actual injection molding parameter values; step three: in the correction stage, replacing the initial injection molding parameters in the first step with the actual injection molding parameters in the second step, and performing the first step again to obtain a new theoretical warping amount; step four: comparing the injection molding parameters of multiple simulation stages with the theoretical warping amount, and optimizing the injection molding parameters through an orthogonal test; step five: and (5) repeating the second step to the fourth step by using the optimized injection molding parameters until the theoretical warping amount reaches an ideal value.

Preferably, the workflow analysis software adopted in the first step is MOLDFLOW.

As shown in fig. 2, the analysis process of the dataflow in the first step mainly includes the following steps:

(1) in three-dimensional software (including but not limited to UG, CATIA, SOLIDWORKS, etc.), designing a three-dimensional diagram of a mold and a product, outputting the three-dimensional diagram into a format (including but not limited to igs, stl, etc.) which can be recognized by the MOLDFLOW, inputting the three-dimensional diagram into MOLDFLOW mold flow analysis software, and meshing the three-dimensional model, wherein the meshing standard is as follows: in the area far away from the gate 5, the grid size is set to be 1/1500-1/1000 of the longest edge of the product; and adopting a refined grid within a range of 15-20 mm close to the gate 5, wherein the size of the grid is 15% -20% of that of the grid in a region far away from the gate 5.

The specific operation steps are (i) grid type setting. Setting the mesh type to solid (3D), the specified unit being millimeters; (ii) and (4) grid division setting. Selecting F3, generating a 3D mould grid, checking that the grid is placed in an activation layer, selecting a job manager, and setting a preset scheme as a priority task; (iii) and (4) setting conventionally. Setting the global side length on the curved surface to be 1/1500-1/1000 of the longest side of the product; checking a matching grid; checking 'stop after generating a curved surface mesh'; and (4) selecting 'extra thinning is applied near the sprue 5', and the thinning value range is set to be 15% -25% of the relative side length. (iv) A tetrahedral option. Selecting a wavefront method under a 3D grid generator; the minimum unit number in the thickness direction is set to be 6-10; the ratio of the side length of the maximum tetrahedron to the side length of the whole tetrahedron in the thickness direction is set to be 1.1-1.5; tetrahedron aspect ratio control, set to auto-optimize. (v) The high-level options of tetrahedron, and the selection of the 'optimization by using a curved surface mesh'; "use surface mesh matching" is chosen; the nodes in the thickness direction are deviated, and 'non-offset uniform distribution' is selected; and (4) grid smoothing treatment, selection and smoothing of all nodes. After the setting is finished, clicking to execute, and immediately dividing the grids.

After the mesh division is completed, mesh statistics is required to be carried out, including statistics of the number of tetrahedrons, statistics of connected nodes, statistics of connected regions, statistics of volume according to unit types, volume divided according to components, aspect ratio and maximum dihedral angle. And through the statistics, observing whether the divided grids are abnormal or not, and repairing or reestablishing the singular grids through operations such as node combination, mobile nodes, exchange edges, node alignment, filling holes, node insertion and the like so as to enable the grid quality to meet the simulation requirement.

(2) Setting basic parameters, namely setting the temperature of heat flow in a hot runner; when the waterway channel 11 is used, an additional pipeline (3D) is selected from the mold flow software, the three-dimensional model of the waterway channel 11 is introduced into the mold flow software, the waterway channel 11 is divided into grids again, the heat quantity near the sprue 5 is more, the water inlet interface is selected at one side close to the sprue 5, and the cooling parameter and the heating parameter obtained by the experiment are input into the MOLDFLOW software.

(3) Analyzing sequence setting, and selecting analysis sequence cooling + filling + pressure maintaining + warping in MOLDFLOW software.

(4) Setting an injection molding process, namely sequentially setting the surface temperature, filling control, melt temperature, speed/pressure switching and pressure maintaining control of the die 2;

(5) and calculating the warping amount.

In the initial design stage, according to empirical values, presetting injection molding parameters, such as the surface temperature of a mold, which is preset to 50-80 ℃; the melt temperature is preset to be 215-245 ℃, and in a mold testing stage, relevant parameters of a mold cavity, such as a surface temperature measured value, a melt temperature measured value, a cavity pressure measured value and the like, are collected in real time, and are introduced into mold flow analysis software again, the warping deformation is recalculated, the difference between the preset value and the measured value is compared, the relation between the simulated warping amount and the actual product warping amount is compared, the optimal injection molding parameters are determined, and the warping deformation is reduced to the minimum.

And determining the injection molding position, namely firstly setting an analysis sequence to be filling, presetting a plurality of gates 5 according to experience, performing filling analysis, and mainly considering the result, namely filling time, pressure during speed/pressure switching, flow front temperature and pressure at the injection position: XY plot, mold clamping force XY plot, time to reach ejection temperature, fill area, pressure, fill tip pressure, shear rate, maximum, wall shear stress, temperature, velocity, viscosity, fill tip freezing factor layer, average volume shrinkage, cavitation, polymer fill area, weld surface movement (3D), weld surface distribution (3D), weld line, path line, cavity weight, and the like. The position of the gate 5 is adjusted by comprehensively considering the above factors.

When the waterway channel 11 is used as a cooling function, the optimal cooling parameters are obtained by the following tests: selecting industrial pure water as a cooling medium, adjusting a mold temperature controller, setting the initial water temperature to be 15-30 ℃, setting the flow rate of cooling water to be 2-6 m/s, and recording the time required for reducing the pressure of the mold pressing sensor 16 to be below 0.2 MPa; recording the time required by the temperature of the mold temperature sensor to be reduced to below 80 ℃, carrying out a test at a water temperature interval of 3 ℃ and a water flow rate interval of 1m/s, and obtaining the cooling parameter with the fastest temperature reduction through an orthogonal test.

When the waterway channel 11 is used as a heating function, the optimal temperature rise parameter is obtained through the following tests: the invention selects the waterway channel 11 to be internally communicated with hot steam and the resistance wire for synchronous heating. The specification of the resistance wire is 2Kw, the pipe diameter is phi 6, 140 ℃ high-temperature steam is introduced, the flow rate of the steam is set to be 2 m/s-6 m/s, the pre-embedded heating wires are synchronously connected, the time required for heating the surface of the mold to 120 ℃ is recorded through a mold temperature sensor, the steam flow rate is tested once every 0.5m/s, and the fastest temperature rise parameter is obtained through an orthogonal test.

In this specification, the schematic representations of the terms are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. The utility model provides a bumper injection mold which characterized in that: the product pouring device comprises a fixed die plate, a fixed die, a movable die plate, a pouring channel, an ejector rod and an inclined top, wherein a product containing cavity is formed between the fixed die and the movable die, and the pouring channel extends into the product containing cavity from the surface of the fixed die plate;

the middle part of the product accommodating cavity protrudes towards the fixed die, reverse buckling parts are formed on two sides of the product accommodating cavity, the ejector rod is suitable for jacking a product towards the fixed die, and the inclined tops are symmetrically arranged at the reverse buckling parts on two sides of the movable die; one end of the inclined top is fixedly connected with the movable template, and the other end of the inclined top is suitable for reciprocating along the direction of the inclination angle of the edge of the back-off part.

2. The bumper injection mold of claim 1, wherein the lifter includes:

the fixed seat is fixed on the movable template;

a guide rail connected to one end of the fixed seat,

the fixed end of the hydraulic cylinder is hinged to the other end of the fixed seat, the movable end of the hydraulic cylinder is connected with the guide rail in a sliding mode, and the hydraulic cylinder is suitable for reciprocating along the axis direction of the guide rail;

and the inclined top insert is positioned at the top of the movable end of the hydraulic cylinder and is suitable for limiting the reverse buckling part of the product.

3. The bumper injection mold according to claim 2, characterized in that: a plurality of waterway channels are arranged inside the movable die in a stacking mode, the waterway channels are offset along the direction of an inner normal line on the protruding surface of the movable die, each layer of water pipes in the waterway channels are arranged in series, and each layer of waterway channel is provided with a water inlet interface and a water outlet interface respectively.

4. The bumper injection mold according to claim 1, characterized in that: the fixed die is internally provided with a hot runner system communicated with the product containing cavity, and the hot runner system comprises a flow distribution plate positioned below the sprue, a plurality of hot nozzle parts communicated with the flow distribution plate and the product containing cavity, and a temperature control box for controlling the temperature of the hot runner system.

5. The bumper injection mold according to claim 4, characterized in that: the hot mouth part comprises a linear hot mouth connected with the upper part of the product containing cavity and a universal hot mouth connected with the back-off part of the product containing cavity.

6. A method for controlling warpage of an article, using the bumper injection mold according to any one of claims 1 to 5, the method comprising the steps of:

the method comprises the following steps: in the simulation stage, a three-dimensional graph of the mold is led into mold flow analysis software to be analyzed to obtain the theoretical warping amount of the product under the condition of initial injection molding parameters;

step two: in the mold testing stage, a mold provided with a plurality of temperature sensors and mold pressing sensors is placed into an injection molding machine, and the state of the product containing cavity is collected in real time to obtain an actual injection molding parameter value;

step three: in the correction stage, replacing the initial injection molding parameters in the first step with the actual injection molding parameters in the second step, and performing the first step again to obtain a new theoretical warping amount;

step four: comparing the injection molding parameters of multiple simulation stages with the theoretical warping amount, and optimizing the injection molding parameters through an orthogonal test;

step five: and (5) repeating the second step to the fourth step by using the optimized injection molding parameters until the theoretical warping amount reaches an ideal value.

7. The method for controlling warpage of a product according to claim 6, wherein: the model flow analysis software adopted in the first step is MOLDFLOW.

8. The method for controlling warpage of a product according to claim 7, wherein: the analysis process of the dataflow in the first step mainly comprises the following steps:

(1) and (3) carrying out meshing on the three-dimensional model of the mold, wherein the meshing standard is as follows: in the area far away from the gate, the grid size is set to be 1/1500-1/1000 of the longest edge of the product; adopting a refined grid within a range of 15-20 mm close to the gate, wherein the size of the grid is 15% -20% of that of the grid far away from the gate area;

(2) setting basic parameters, namely setting the temperature of heat flow in a hot runner;

(3) analyzing sequence setting, namely selecting an analysis sequence to cool, fill, maintain pressure and warp in MOLDFLOW software;

(4) setting an injection molding process, namely setting the surface temperature of a mold, filling control, melt temperature, speed/pressure switching and pressure maintaining control in sequence;

(5) and calculating the warping amount.

9. The method for controlling warpage of a product according to claim 8, wherein: the step one, the mold flow analysis process further comprises the steps of drawing a waterway channel model and then leading the waterway channel model into mold flow analysis software, and when the mold enters a pressure maintaining stage, introducing industrial pure water into the waterway channel to cool the mold; and after the product is taken out, introducing high-temperature steam into the waterway channel to heat the surface of the mold.

10. The method for controlling warpage of a product according to claim 9, wherein: the mold heating adopts the way that high-temperature steam is introduced into a waterway channel and is synchronously heated with a resistance wire.