CN107971488B

CN107971488B - Laser 3D printing apparatus

Info

Publication number: CN107971488B
Application number: CN201610939098.6A
Authority: CN
Inventors: 席义清
Original assignee: Hunan Shangyida Technology Co ltd
Current assignee: Hunan Shangyida Technology Co ltd
Priority date: 2016-10-24
Filing date: 2016-10-24
Publication date: 2021-03-26
Anticipated expiration: 2036-10-24
Also published as: CN107971488A

Abstract

The invention relates to laser 3D printing equipment which comprises a rack part, a forming part, a gas protection part, a laser scanning part, a powder paving part and a preheating part, wherein the forming part, the gas protection part, the laser scanning part, the powder paving part and the preheating part are fixed on the rack part, the forming part is an internal cavity which is enclosed by a plurality of parts fixed on the rack part and is relatively sealed, the gas protection part is externally arranged on the rack part and is circularly communicated with the forming part, the laser scanning part is movably fixed along the outer side of the forming part, the preheating part is fixed on the other side opposite to the forming part and is telescopically fixed in the rack part, and the powder paving part extends to the fixing of the internal cavity of the forming part. The problem of laser energy waste caused by the fact that laser easily forms diffusion or reflection in the forming process is effectively avoided, and the problem that the yield of products is not high due to the fact that the shape of the formed powder which is heated unevenly and accumulated is easily changed is solved.

Description

Laser 3D printing apparatus

Technical Field

The invention belongs to the field of additive manufacturing, and particularly relates to laser 3D printing equipment for melting/melting powder layer by layer to form a shape by utilizing laser based on a scanning galvanometer.

Background

Laser 3D prints as an increase material manufacturing technique, has higher printing precision and printing speed, and the material application scope is wide, is applicable to the machine-shaping of multiple metal or non-metallic material. Laser 3D printing is a technology for directly producing parts by utilizing a three-dimensional solid model generated by CAD, the main principle is that an infrared laser is adopted as an energy source, the used molding material is mostly powder material, during processing, the powder is firstly preheated to a temperature slightly lower than the melting point of the powder, and then the powder is paved under the action of a scraping roller; the laser beam is selectively sintered under the control of a computer according to the information of the layered cross section, the next layer of sintering is carried out after one layer is finished, and redundant powder is removed after all the layers of sintering are finished, so that the sintered part can be obtained.

In order to ensure the forming precision and reduce or eliminate the thermal stress caused by excessive temperature difference between the powder before and after processing, the powder needs to be preheated to be closer to the melting temperature before and after the laser scanning melts the powder. Therefore, the temperature in the molding working cavity is high, and the thermal expansion adversely affects moving parts of the laser 3D printing device, such as a powder spreading device, and reduces the movement precision. To reduce this adverse effect, it is desirable to keep the components that control the accuracy of the motion as far away from the temperature-affected zone as possible.

Meanwhile, in order to avoid oxidation deformation of the metal powder in a molten state, inert gas protection is required in the processing process, and in order to realize the inert gas environment, a vacuum pump is used for vacuumizing an atmosphere protection chamber, then inert protection gas is filled into the atmosphere protection chamber, the atmosphere protection chamber is repeatedly vacuumized, and a purer inert gas environment can be obtained after the inert protection gas is filled for several times.

The molding chamber in the prior art has the following problems:

1. at present, the inside station of the shaping storehouse for laser 3D prints is single, and the size of its station size has restricted the scope of shaping part size, leads to the empty stroke of walking of laser emission head more, and laser generator needs frequent switching, has increased the time of shaping latency, and single station is also not high to inert gas's utilization ratio.

2. Because the object of laser 3D printing and forming processing is particles with small particle radius, the formed particles with small radius are easily adhered to the lens by directly injecting protective gas into the forming bin, so that laser is diffused or reflected, and the energy of the laser is weakened.

3. Laser 3D prints the shaping and just heats laser focus part for the shaping powder of equipartition in advance is heated under the uneven condition, and the shape of piling up changes easily, thereby influences the appearance of the part of last shaping, leads to the yield of product to reduce.

4. The existing laser 3D forming equipment has the defects that when a formed workpiece with poor heat conductivity or large thickness is processed, due to the existence of heat conduction temperature gradient, powder to be formed cannot be effectively preheated, and the processing and forming are difficult; or the heating mode of radiation irradiation is adopted to comprehensively preheat the molding powder, so that the energy consumption is high, the precision of the molded part is directly influenced, and the molding machine is only suitable for molding parts with simple molding and low precision requirement.

In view of the above, this also constitutes a need for further improvement of the design of the laser 3D printing apparatus in order to solve the existing technical problems.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide laser 3D printing equipment, which breaks through the limitation of the size of an internal station of a forming bin in the prior art on laser melting forming, solves the problem that the accumulated shape is easy to change under the condition that the formed powder uniformly distributed in advance is not uniformly heated due to only local heating through laser focusing in the prior art, thereby affecting the appearance of a finally formed part and reducing the yield of products, and solves the problem that the traditional injection of protective gas easily causes formed particles with small radius to adhere to a lens, so that laser is easy to form diffusion or reflection, and the energy of the laser is weakened.

In order to achieve the purpose, the invention provides the following technical scheme:

a laser 3D printing device comprises a rack part, a forming part, a gas protection part, a laser scanning part, a powder spreading part and a preheating part, wherein the forming part, the gas protection part, the laser scanning part, the powder spreading part and the preheating part can be fixed on the rack part, the forming part is an internal cavity which is enclosed by a plurality of parts fixed on the rack part and is relatively sealed, the gas protection part is externally arranged on the rack part and is circularly communicated with the forming part, the laser scanning part is movably fixed along the outer side of the forming part, the preheating part is fixed on the other side opposite to the forming part, the preheating part is fixed in the rack part in a telescopic mode and comprises a heating partition plate and a heating assembly which are sequentially attached to the forming part, and the powder spreading part extends to the fixing of the internal cavity of the forming part; overcomes the defects of low working efficiency, low utilization rate of inert gas and limited forming size of the laser 3D printing equipment in the prior art, effectively avoids the difficult problem of laser energy waste caused by easy diffusion or reflection of laser in the forming process, and solves the difficult problem of low yield of products caused by easy change of accumulated shapes due to uneven heating of forming powder, the forming cavity in the forming part can be greatly expanded, at least two forming stations are arranged in the forming part, two adjacent forming stations in the forming stations are arranged at intervals in a flush manner, so that the forming machine can carry out laser melting operation of a plurality of stations at one time, the utilization rate of the laser generator can be effectively improved, the waiting time of the machine is reduced, therefore, the laser forming machine can perform parallel cooperative operation, and the processing efficiency is greatly improved.

Preferably, in order to improve the processing efficiency and avoid the deviation of the installation position of each assembly part caused by thermal expansion in the processing process, the cooling part is communicated with the forming part and fixed on one side of the frame part, and comprises a cooling box and a communication pipeline.

Preferably, the frame part includes a fixed frame for supporting and fixing other components, and a lifting device for adjusting a molding height, wherein the lifting device is fixed inside a frame of the frame part, and is vertically telescopically arranged from a bottom end upward.

Preferably, the fixing frame comprises a forming plate, a heating plate, a supporting plate and a skirt board fixed on the outer peripheral surface of the frame part, wherein a gap is kept between the skirt board and the forming plate and between the skirt board and the heating plate.

Preferably, the gas protection part comprises an atmosphere protection device and an air filtering device which are circularly communicated with the forming part, the atmosphere protection device and the air filtering device are separately arranged on the outer side of the frame part, and further, the atmosphere protection device comprises a gas generation assembly for generating protective gas and a connecting pipeline for communicating with the forming part; in order to facilitate the air that contains oxygen in getting rid of the shaping portion, avoid the oxidation in the course of working, the connecting tube is two, including admission line and exhaust duct, on the side of shaping portion is fixed to the dislocation in vertical direction to this, through the protective gas who injects different density, can effectually arrange the air that contains oxygen to the greatest extent, builds an anaerobic processing environment.

Furthermore, the laser scanning part comprises a fixed base plate connected with the frame part, a cross beam fixed with the base plate, and a vibrating mirror movably fixed on the cross beam under the driving of the driving assembly.

Preferably, the driving assembly comprises a penetrating beam, a rolling ball screw rod extending and fixing along the width direction of the fixed base plate, and a motor providing driving power, wherein the motor is fixed on the end side face of the fixed base plate in the width direction, connected with the rolling ball screw rod, and vertically meshed and fixed with the beam; therefore, the rotary motion of the motor is converted into the linear motion of the beam through the ball screw pair, so as to drive the vibrating mirror fixed on the beam to move along the extension direction of the ball screw.

Preferably, in order to realize the cooperative operation of the plurality of processing cavities and improve the high efficiency, at least two vibrating mirrors are arranged on two sides of the cross beam respectively.

Preferably, the powder spreading part comprises a powder tank fixed above the frame part, a powder spreading device extending into the forming part, a recovery tank fixed on the side surface of the bottom of the frame part and communicated with the bottom end of the forming part through a recovery pipe, and a powder collecting device matched with the frame part, wherein the sealing device keeps the sealing of the forming powder in the forming process and is used for collecting the forming powder leaked in the processing process to form secondary sealing; therefore, the sealing device ensures good sealing effect of each part in the forming process, and the powder collecting device arranged in a sealing way with the frame part is adopted, so that the forming powder which is not completely sealed can be recycled, and the problem that the forming powder is easy to leak among parts moving relatively in the forming process is solved;

more preferably, the powder collecting means is provided below the sealing means in sealing engagement with the frame portion to collect molding powder accumulated on the side wall of the frame portion during the machining movement and leaked during the relative movement.

Preferably, the powder collecting device comprises a sealing rubber strip fixed with the frame part in a sealing manner and a powder collecting box used for collecting the molding powder, wherein the powder collecting box is an open sealing accommodating cavity, one end of the sealing rubber strip is sealed, and the other end of the sealing rubber strip, which is arranged oppositely, is open and is communicated with the inside of the powder collecting box, so that the molding powder which is possibly leaked in the molding process can be effectively collected and recovered to form secondary sealing.

Compared with the prior art, the invention has the following advantages and beneficial effects: the laser 3D printing equipment provided by the invention overcomes the defects of low working efficiency, low inert gas utilization rate and limited forming size of the laser 3D printing equipment in the prior art, effectively solves the problems of waste of laser energy caused by diffusion or reflection easily formed by laser in the forming process and low product yield caused by the fact that the shape of formed powder accumulated by uneven heating is easy to change, and provides the laser 3D printing equipment for melting/melting the powder layer by layer to form forming by using laser based on the scanning galvanometer

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 illustrates a schematic diagram of a laser 3D printing apparatus implemented in accordance with an embodiment of the invention;

FIG. 2 illustrates a schematic diagram of another laser 3D printing apparatus implemented in accordance with an embodiment of the invention;

FIG. 3 illustrates a schematic diagram of a forming silo suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention;

FIG. 4 illustrates a schematic cross-sectional view of another molding compound suitable for use in a laser 3D printing apparatus implemented in embodiments of the invention;

FIG. 5 illustrates a schematic cross-sectional view of a preheat section suitable for use in a laser 3D printing apparatus implemented in embodiments of the invention;

fig. 6 shows a schematic diagram of another preheating section suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention;

fig. 7 shows a schematic structural diagram of a laser scanning section suitable for a laser 3D printing apparatus implemented in an embodiment of the present invention;

FIG. 8 shows a schematic cross-sectional view of a powder laying section suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention;

FIG. 9 illustrates a partial schematic view of a powder seal suitable for use in a laser 3D printing apparatus implemented in embodiments of the invention;

fig. 10 shows a schematic cross-sectional view of another powder sealing device suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Referring to fig. 1-10, fig. 1 illustrates a schematic diagram of a laser 3D printing apparatus implemented according to an embodiment of the invention; FIG. 2 illustrates a schematic diagram of another laser 3D printing apparatus implemented in accordance with an embodiment of the invention; FIG. 3 illustrates a schematic diagram of a forming silo suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention; FIG. 4 illustrates a schematic cross-sectional view of another molding compound suitable for use in a laser 3D printing apparatus implemented in embodiments of the invention; FIG. 5 illustrates a schematic cross-sectional view of a preheat section suitable for use in a laser 3D printing apparatus implemented in embodiments of the invention; fig. 6 shows a schematic diagram of another preheating section suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention; fig. 7 shows a schematic structural diagram of a laser scanning section suitable for a laser 3D printing apparatus implemented in an embodiment of the present invention; FIG. 8 shows a schematic cross-sectional view of a powder laying section suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention; FIG. 9 illustrates a partial schematic view of a powder seal suitable for use in a laser 3D printing apparatus implemented in embodiments of the invention; fig. 10 shows a schematic cross-sectional view of another powder sealing device suitable for use in a laser 3D printing apparatus implemented in an embodiment of the invention.

The invention provides laser 3D printing equipment for melting/melting powder layer by layer to be formed by stacking based on scanning galvanometers, aiming at overcoming the defects of low working efficiency, low inert gas utilization rate and limited forming size of laser 3D printing equipment in the prior art, effectively avoiding the difficult problem of laser energy waste caused by the fact that laser is easy to form diffusion or reflection in the forming process and the difficult problem of low product yield caused by the fact that the shape of formed powder which is heated unevenly and stacked is easy to change.

As shown in fig. 1 to 10, the laser 3D printing apparatus according to the present invention comprises a frame portion 10, a forming portion 20 fixed on the frame portion 10, a gas-protecting portion 30, a laser scanning portion 50, a powder-spreading portion 60, and a preheating portion 40 capable of preheating the powder, wherein the forming portion 20 is a relatively sealed internal cavity surrounded by a plurality of components fixed to the frame portion 10, the gas-protecting portion 30 is externally disposed on the frame portion 10 and is in circulatable communication with the forming portion 20, the laser scanning portion 50 is movably fixed along the outer side of the forming portion 20 so that the generated laser beam can be selectively applied to the working space of the internal cavity of the forming portion 20, the preheating portion 40 is fixed on the opposite side of the forming portion 20 and is telescopically fixed in the frame portion 10, the powder-spreading portion 60 partially extends to the fixing of the internal cavity of the forming portion 20, so that the molding powder is conveyed to the inside of the molding part 20 and uniformly laid. The laser scanning part 50 moves along the outer side of the forming part 20 to drive the laser beam to irradiate locally in the forming part 20, and the powder spreading part 60 uniformly spreads the forming powder in the forming part 20 in advance to be heated locally and continuously, so that the local forming powder is melted and condensed to finally form the appearance of a specific part.

Specifically, as shown in fig. 1 and 2, in a specific embodiment, the molding part 20 is mounted on the upper portion of the frame part 10, the laser scanning part 50 is fixed on the upper end surface of the molding part 20, the preheating part 40 is fixed in close contact with the lower end surface of the molding part 20, the powder spreading part 60 is higher than the upper surface of the molding part 20, and is attached to the side surface of the molding part 20 to extend into the molding part 20, so that the molding cavity inside the molding part 20 can be greatly expanded. In a preferred embodiment, the forming bin inside the forming part 20 is provided with at least two forming stations, and two adjacent forming stations are arranged at intervals in parallel and level in the forming stations, so that the forming machine can perform laser melting operation on a plurality of stations at one time, the utilization rate of a laser generator can be effectively improved, the waiting time of the machine is reduced, the cooperative operation that one laser forming machine can be operated in parallel is realized, and the processing efficiency is greatly improved. Further, in order to improve the processing efficiency and prevent the deviation of the installation position of each assembly component caused by thermal expansion in the processing process, a cooling part 70 fixed around the forming part 20 is further included.

In the embodiment of the present invention, as shown in fig. 1 and 10, the rack part 10 includes a fixed frame 11 for supporting and fixing other components, and a lifting device 12 for adjusting a molding height, wherein the lifting device 12 is fixed inside a frame of the rack part 10, and is disposed to be upwardly extendable and downwardly from a bottom end in a vertical direction, the fixed frame 11 includes a molding plate 111, a heating plate 112, and a support plate 114, and a skirt plate 113 fixed to an outer circumferential surface of the rack part 10, wherein the skirt plate 113 is fixed to the molding plate 111 and the heating plate 112 with a gap therebetween.

Forming section

The molding part 20 comprises a molding substrate 21, a molding assembly 22 fixed on the molding substrate 21, a cooling assembly 24, a lens 25, and an access assembly 23 for communicating with a shielding gas, wherein the lens 25 is embedded on the molding substrate 21, the molding assembly 22 protrudes and extends along the outer side of the molding substrate 21 and is communicated with the gas access assembly 23, and the cooling assembly 24 surrounds the molding assembly 22 for fixing. In the present invention, the forming assembly 22 comprises at least two forming stations 221, the forming stations 221 being connected in series with gas nozzle connections 222, communicating in groups with the gas access assembly 23. Thus, the forming station 221 is maintained in a clean protective gas environment by the protective gas communicated through the gas access assembly 23. Wherein, the forming component provided by the invention comprises at least two forming stations, and two adjacent forming stations in the forming stations are arranged at intervals in a flush manner, so that a forming machine can conveniently carry out laser melting operation of a plurality of stations at one time, namely, the multi-station scanning simultaneous processing operation under a plurality of sets of laser galvanometers can effectively improve the utilization rate of the laser generator, reduce the movement and waiting time of the machine table, thereby realizing the parallel cooperative operation of a laser forming machine table, greatly improving the processing efficiency, and can avoid uneven heat distribution of laser in the local heating process through the adjustment of the cooling component, the shape of the accumulated molding powder which is uniformly distributed in advance is easy to change, the appearance of the finally molded part is influenced, and the yield of the product is reduced.

It should be noted that there are various embodiments that can implement the parallel cooperative operation of one laser forming machine, for example, the number, specific structure and arrangement of forming assemblies, the number and arrangement of laser heads, and the like, and for convenience of description, the multi-station cooperative operation implemented under a plurality of sets of laser galvanometers is taken as an exemplary description.

As shown in particular in figures 3 and 4. Structurally, the forming assembly 22 can be designed to comprise a forming station 221 and an air nozzle joint 222 communicated with the forming station 221, wherein the cross section of the forming station 221 is circular, and the axes of at least two forming stations 221 are distributed in a horizontal and/or vertical direction in a straight line, so that the laser forming machine is conveniently and accurately positioned, and the forming operation in each forming bin is ensured to be consistent in reference. Preferably, there are four molding stations 221, and the axes of the molding stations are connected into an equilateral quadrilateral and fixed on the molding substrate 21, and further, for the convenience of processing, the molding stations 221 with circular cross-section have axes distributed at the corners of the equilateral quadrilateral. Various modifications are possible, particularly based on the number of forming stations and the arrangement of the relative positions, and all such modifications are intended to fall within the scope of the present invention.

In the embodiment of the present invention, in order to ensure the consistency of the forming quality of the laser in multi-station cooperative operation under multiple galvanometers, the gas access assembly 23 is fixed on the forming substrate 21 and is set to communicate with the forming assembly 22 in a group, as shown in fig. 3, the forming assembly 22 distributed in the vertical direction is taken as a group for exemplary illustration. Specifically, the gas protecting assembly 23 includes a first gas distributing block 232 communicated with the first forming assembly 22, and a second gas distributing block 233 communicated with the second forming assembly 22, wherein the first forming assembly 20 includes two forming stations 221 arranged in line with the vertical axis, the second forming assembly 22 includes another two forming stations 221 arranged in line with the vertical axis, and the first gas distributing block 232 and the second gas distributing block 233 are respectively communicated with the forming stations 221 through the gas nozzle joint 222. Therefore, the protective gas enters the forming station through the two gas distributing blocks and the air tap connector, so that the protective gas environments in two different forming stations in the same forming bin are ensured to be consistent or close, the forming conditions in the multi-station forming stations of the system operation are consistent, and the quality of the final parts is ensured.

Preferably, the gas access module 23 further comprises a blowing flange 231 fixed on the molding substrate 21, and a blowing hole 2331 is formed in the end side surface of the blowing flange 231 parallel to and opposite to the lens 25, so that the protective gas entering the molding chamber can be controlled more conveniently and uniformly through the blowing hole 2331. Further, in order to avoid the local density difference caused by the protective gas directly blowing to the mirror surface of the lens 25, and the laser light is diffused or reflected on the lens 25, the blowing holes 2331 are arranged in a staggered manner at different angles with the lens 25, so that an air curtain is formed below the lens, and dust in the molding bin or other impurities formed in the molding process are prevented from being adhered on the lens.

Preferably, in order to increase the utilization rate of the shielding gas and avoid leakage of the shielding gas, a first sealing member 234 is interposed between the gas access assembly 23 and the molding substrate 21, and a second sealing member 235 is interposed between the lens 25 and the molding substrate 21. Further, the second hermetic seal 235 further includes a coarse seal 2351 and a fine seal 2352 disposed on different sealing surfaces, wherein the coarse seal 2351 is interposed between the lens 25 and the outer side joint sealing surface of the molding substrate 21, and the fine seal 2352 is interposed between the lens 25 and the inner side joint sealing surface of the molding substrate 21, preferably, the outer side joint sealing surface and the inner side joint sealing surface are staggered to form a step, so as to ensure the lens and the substrate to maintain a hermetic contact through the dual seals.

In this embodiment, the cooling assembly 24 is including offering on the shaping base plate 21, a cooling pipeline 241 for carrying cooling medium, and inlay on the shaping base plate 21, the cooling module that arranges around the shaping subassembly 22, wherein, the cooling assembly includes first cooling module 242 and the second cooling module 243 that the horizontal interval set up, and the third cooling module 244 of vertical setting, with this, through a plurality of cooling modules that set up, can be timely, the quick heat conduction of collecting around the shaping storehouse will be taken away, thereby avoided laying in the shaping storehouse shaping powder because local heat distributes unevenly, the change easily takes place for accumulational shape, thereby influence the appearance of last fashioned part, lead to the problem that the product yield reduces.

In order to ensure the heat conduction efficiency of the cooling module, the cooling pipeline 241 is communicated with the cooling portion 70 and penetrates through the cooling module, and the heat absorbed by the cooling module is continuously taken away by the cooling medium flowing in the cooling pipeline.

Specifically, the cooling pipeline 241 includes a first water inlet pipe 2411 and a first water outlet pipe 2412, and a second water inlet pipe 2413 and a second water outlet pipe 2414;

the first cooling module 242 includes a first water inlet 2421 and a first water outlet 2422, and cooling pipes disposed therein and respectively connected thereto;

the second cooling module 243 includes a second water inlet port 2431, a second water outlet port 2432, and cooling pipes respectively connected to the second water inlet port 2431 and the second water outlet port 2432;

the first water inlet interface 2421 is communicated with the second water inlet pipe 2413 through a pipeline, the first water outlet interface 2422 is communicated with the second water outlet pipe 2414, and a cooling pipeline arranged inside the first cooling module 242 forms a cooling circulation loop;

the second water inlet interface 2431 is communicated with the first water inlet pipe 2411 through a pipeline, and the second water outlet interface 2432 is communicated with the first water outlet pipe 2412 to form a cooling circulation loop with a cooling pipeline arranged inside the second cooling module 243.

Further, to ensure uniformity of heat distribution of the molding assembly 22, the third cooling modules 244 are two pieces sandwiching the molding assembly 22.

Gas shield

In the present embodiment, as shown in fig. 2, the gas protecting portion 30 includes an atmosphere protecting device 31 and an air filtering device 32 which are circularly communicated with the forming portion 20, the atmosphere protecting device 31 and the air filtering device 32 are separately provided at the outer side of the frame portion 10, and the atmosphere protecting device 31 includes a gas generating assembly 311 for generating a protecting gas, and a connecting duct 312 for communicating with the forming portion 20. In a preferred embodiment, in order to facilitate the removal of the air containing oxygen in the forming portion 20 and avoid oxidation during the processing, two connecting pipes 313 are provided, including an air inlet pipe and an air outlet pipe, which are fixed on the side of the forming portion 20 in a staggered manner in the vertical direction, so that the air containing oxygen can be effectively exhausted by injecting the protective gas with different densities, thereby creating an oxygen-free processing environment.

Preheating section

In this embodiment, the preheating part 40 includes a heating partition plate 41 fixed to be closely attached to the forming part 20, and a heating assembly 45 fixed to be attached to the heating partition plate 41, and heat is conducted to the forming part 20 through the heating partition plate 41 by continuous heating of the heating assembly 45, so as to realize uniform warming and preheating of the forming powder laid in the forming part 20, thereby avoiding the problem of nonuniform local heating degree caused by direct heating of the forming powder and residual stress in the formed part caused by temperature difference, overcoming the defect that in the prior art, the quality of the final 3D printed attacked part is directly affected due to nonuniform distribution of the residual stress in the part caused by irradiating the forming powder with radiation and selecting local radiation irradiation for heating, the temperature difference between the part and the accessory is not large, the product is easy to adhere to the workpiece after being dissolved, thereby affecting the precision of the workpiece and easily generating defects such as burrs or burrs.

As shown in fig. 5 and fig. 6, specifically, the preheating part 40 includes a heating partition plate 41 fixed to the attached molding substrate 21, and a heating assembly 45 fixed to the attached heating partition plate 41, after the heating assembly 45 is heated, heat is transferred to the molding substrate 21 through the heating partition plate 41, so that uniform heat transfer is achieved, and the problem of product quality caused by local temperature difference is avoided.

Preferably, a temperature sensor 42 for monitoring temperature change is further fixed on the heating partition plate 41, wherein one end of the temperature sensor 42 is attached to the heating partition plate 41, and the other end of the temperature sensor 42, which is opposite to the heating partition plate 41, is thermally isolated from the heating partition plate 41, preferably, a pre-tightening structure 43 of the temperature sensor is sleeved on the outer peripheral side of the temperature sensor 42, so that the temperature measuring surface of the temperature sensor is in close contact with the heating partition plate, thereby ensuring the accuracy of the obtained data, meanwhile, the pre-tightening structure 43 is fixed on the heating partition plate 41, sleeved on the outer peripheral side of the sensor 42, and spaced from the sensor 42, and forms a closed-loop internal thermal insulation space with the sensor 42, so as to isolate the heat transfer with the heating assembly 45, thereby avoiding the measurement error caused by the temperature difference between the heating assembly 45 and the heating partition plate 41, further, the temperature sensor, the monitoring error is controlled within 0.1-1 ℃, and the detection sensitivity and stability are high.

In a preferred embodiment, the forming substrate heating system further includes a PLC control system capable of automatically controlling power on and off, and includes an intelligent temperature switch 44 having an early warning function, wherein the intelligent temperature switch 44 electrically connected to the PLC control system is fixed on the heating partition 41 and located on the same side as the sensor 42, and when the temperature sensor 42 detects that the temperature of the forming portion 21 exceeds the maximum set value of the intelligent temperature switch 44, the PLC control system is automatically powered on or powered off, so that the whole set of heating system constitutes an automatically controlled closed-loop system.

Preferably, since the heating area is relatively large, the local single-point heating also has the problem of temperature gradient, and the heating time is long, the temperature rise is slow, and the operation efficiency is low, meanwhile, in the later stage of the forming, different processing technologies are selected for the later stage processing technology of the formed workpiece due to different special requirements of structural characteristics or performance, for example, the formed workpiece reduces brittleness, eliminates or reduces internal stress, and stabilizes the size of the workpiece, a tempering processing technology is usually adopted, a local area of the workpiece needs certain strength and toughness, usually needs to be subjected to tempering treatment, however, the heating conditions of the back-end processing industry are different, which requires regional temperature control of the formed workpiece, as shown in the figure, the heating assembly 45 includes at least one movably assembled heating plate 452 and a fixed plate 451 for fixing 452, the heating plate 452 may be freely assembled to form a continuous and/or intermittent heating zone. Specifically, in order to facilitate the quick assembly of heating plate 452, heating plate 452 detachable inlays on fixed template 451, through with heating element 45 regional share heating element alone, on the one hand can heat simultaneously, avoids the temperature gradient problem of single-point heating, on the other hand, can realize local regional temperature independent control, satisfies the demand of the different processing technology of finished piece back end after the shaping, realizes the temperature requirement of the different technologies of same part back end.

In a preferred embodiment, the heating plates 452 have the same shape, are made of materials with different thermal conductivity coefficients, and are assembled by selecting the heating plates 452 with different thermal conductivity coefficients, so that different post-processing processes can be integrated into the formed part to meet the requirement of performance differentiation among different parts forming the part. For example, one of the heating plates 452 in the assembly combination is made of copper or aluminum with a relatively high thermal conductivity, so that the central part of the product can be cooled faster than the periphery of the product, and thus, comprehensive selection of different technological means is realized. Further, the assembled heating plate 452 has holes (not shown) formed therein for receiving different cooling media, such as water, brine, or oil, to meet different requirements of post-processing heat treatment, and preferably, the holes formed in the heating plate 452 are blind holes.

The working principle and the process of the preheating part are as follows:

before the 3D printing equipment spreads powder, the heating assembly 45 is electrified to heat the heating partition plate 41;

the temperature sensor 42 is tightly attached to the heating partition plate 41, the resistance value of the temperature sensor changes along with the temperature rise of the heating partition plate 41, and the intelligent temperature switch 44 reads the real-time numerical value of the resistance value through the PLC control system to determine the temperature value of the heating partition plate 41;

when the temperature of the heating partition plate 41 reaches a preset temperature value, the intelligent temperature switch 44 controls the heating partition plate 41 to cut off the power supply;

after the heating partition plate 41 is powered off, the temperature of the heating partition plate is gradually reduced, the resistance value of the temperature sensor 42 is changed along with the reduction of the temperature of the heating partition plate 41, and the intelligent temperature switch 44 reads the real-time numerical value of the resistance value through the PLC;

when the temperature of the heating partition plate 41 is lower than the preset temperature value, the intelligent temperature switch 44 controls the heating partition plate 41 to be powered on, and continuously heats the heating partition plate 41;

the temperature of the heating partition plate 41 is always changed within a certain range by continuously and circularly switching on and off;

by heating for a while, the temperature of the heating partition plate 41 is gradually raised, about 80 °;

starting simultaneous heating of the molded substrate 21;

when the temperature of the heating partition plate 41 exceeds the temperature set by the intelligent temperature switch 44, the intelligent temperature switch 44 automatically alarms, and triggers the PLC control system to cut off the power supply of the heating partition plate 41, so that accidents are avoided.

Laser scanning unit

In this embodiment, as shown in fig. 7, the laser scanning unit 50 includes a fixed base plate 51 connected to the frame part 10, a beam 52 fixed to the base plate 51, and a vibrating mirror 53 movably fixed to the beam 52 under the driving of a driving assembly 54, wherein the driving assembly 54 can be specifically designed to be a combination of multiple driving members, and only needs to be able to drive the vibrating mirror 53 to move freely on the fixed base plate 51, for example, as shown in fig. 7, an embodiment includes a screw rod 541 extending and fixed along the width direction of the fixed base plate 51 and penetrating the beam 52, and a motor 542 providing driving power, wherein the motor 542 is fixed on the end side surface of the fixed base plate 51 in the width direction, connected to the screw rod 541 and fixed in a perpendicular engagement with the beam 52, so that the rotary motion of the motor 542 is converted into a linear motion of the beam 52 by a screw rod ball rod pair, thereby driving the galvanometer 53 fixed on the cross beam 52 to move along the extending direction of the ball screw 541. As to the specific structure of the other driving components 54, it should be easy for those skilled in the art to understand, and therefore, the detailed description is omitted here. Therefore, under the action of the driving assembly 54, the vibrating mirrors 53 can be accurately moved, so that the laser beams emitted by the laser emitters can be focused on the molding powder, and preferably, in order to realize the cooperative operation of a plurality of processing cavities and improve the high efficiency, at least two vibrating mirrors 53 are respectively arranged on two sides of the cross beam 52.

Powder spreading part

In the present embodiment, as shown in fig. 1, 2, 8 and 9, the powder spreading portion 60 includes a powder tank 61 fixed higher than the frame portion 10, a powder spreading device 62 extending into the forming portion 20, a recovery tank 63 fixed on the bottom side of the frame portion 10 and communicating with the bottom end of the forming portion 20 through a recovery pipe 64, and a powder collecting device 66 cooperating with the frame portion 10, for keeping the sealing of the forming powder during the forming process and collecting the forming powder leaked during the processing process to form a secondary seal, wherein the sealing device 65 is interposed between the forming portion 20, the preheating portion 40 and the frame portion 10, and the powder collecting device 66 is connected in a sealing manner against the frame portion 10 and is disposed at a distance from the sealing device 65. Therefore, the sealing device 65 ensures good sealing effect of each part in the forming process, and the powder collecting device 66 arranged in a sealing way with the frame part 10 is used, so that the forming powder which is not completely sealed can be recycled, and the problem that the forming powder is easy to leak between each part which moves relatively in the forming process is solved.

Preferably, a powder collecting device 66 is provided below the sealing device 65 in sealing engagement with the frame portion 10 to collect molding powder that may accumulate on the side walls during the machining movement of the frame portion 10 and leak during the relative movement.

As shown in fig. 9 and 10, one end of the sealing device 65 is clamped on the supporting plate 114, and the other end of the sealing device 65, which is opposite to the skirt board 113, is provided with a pre-pressing arrangement, so that a closed cavity for containing the molding powder is defined between the molding plate 111, the heating plate 112, the skirt board 113 and the sealing device 65, and meanwhile, the molding powder contained in the closed cavity is ensured to be not easy to leak in the process of relative up-and-down movement of the skirt board 113 relative to the supporting plate 114. In this embodiment, the sealing device 65 provides a continuous force by means of a pre-stressed member, such as a compressed spring, pre-stressed rubber or other deformable material that is resiliently resistant to recovery, to provide intimate contact with the skirt 113.

Taking a spring as an example for further explanation, as shown in fig. 9, specifically, the sealing device 65 includes a plurality of sealing strips 651 for sealing, a pressing plate 652 for fixing the sealing strips 651, and a spring 653 for providing a pre-pressure, wherein the spring 653 is pre-pressed and fixed on the frame portion 10, and the sealing strips 651 are pre-pressed and abutted against the spring 653 by the pressing plate 652, so that the pressing plate 652 is continuously operated by the pre-pressure after the spring 653 is pressed, and the sealing strips 651 can be ensured to be in contact with the skirting board 113 with a certain pre-pressure, thereby ensuring the sealing effect between the sealing strips 651 and the skirting board 113.

Further, in order to ensure the sealing effect at the corner where two adjacent sealing strips 651 meet, a corner block 654 having a substantially right-angled shape is further provided, two short side end sides of the corner block 654 extend toward the pressing plate 652, respectively, a longer side is processed with an inclined plane, and a pre-pressed spring 653 is clamped between the longer side and the frame part 10.

In a preferred embodiment, the sealing device 65 further comprises a limiting device for clamping the spring 653 to provide a pre-pressure for the sealing strip 651, specifically, the limiting device comprises a first limiting block 655, a spring 653 with a pre-pressure for clamping, a second limiting block 657 for providing a pre-pressure for the corner block 654, and a fastening assembly 656 for providing a fixed position for the first limiting block 655 and the second limiting block 657, wherein the fastening assembly 656 extends along the length direction of the first limiting block 655, so that the sealing device 65 can be conveniently provided with a continuous pressure to ensure the continuity of the sealing effect.

In this embodiment, referring to fig. 10, in view of the fact that the radius of the particles of the molding powder is very small, during the molding process, the cavity for containing the molding powder is surrounded by the skirt board 113, the molding board 111 and the heating board 112 which move relatively to each other, and the molding powder is likely to leak and cause waste during the up-and-down repeated movement, the powder collecting device 66 includes a sealing rubber strip 661 hermetically fixed to the frame portion 10, and a powder collecting box 662 for collecting the molding powder, wherein the powder collecting box 662 is an open sealed containing cavity, one end of the sealing rubber strip 661 is sealed, and the other end of the sealing rubber strip 661 is open and is connected to the powder collecting box 662 in a communicating manner, so that the molding powder which is likely to leak during the molding process can be effectively collected and recovered to form a secondary seal.

Specifically, joint strip 661 one end and rack portion 10 sealing fixation, it fixes in joint strip 661's below to receive powder box 662, the setting with one end open-ended joint strip 661 intercommunication, furthermore, joint strip 661 includes the stiff end fixed with skirt board 113, and set up the open end of through-hole and receipts powder box 662 intercommunication, wherein, joint strip 661's stiff end is towards the downward extension of open end slope, so that the formation powder who reveals from rack portion 10 can be too smooth along its inclined plane, rely on self gravity to fall into in receiving powder box 662 automatically, avoid piling up in the fixed connection department of joint strip 661 and skirt board 113 at the formation powder.

The above description has been given by way of example of the powder collecting device 66 being implemented as a sealing strip and a compact, but it will be apparent to those skilled in the art that other similar structures than this may be devised on the basis of the above disclosure. For example, the collecting device having a funnel shape provided in a sealed manner with respect to the housing portion 10 or the collecting device extending from the housing portion 10 integrally formed therewith may be required only to be able to collect the leaked molding powder to form a secondary seal. Besides, the sealing structure can comprise a plurality of groups of extension plates, and can also comprise a plurality of groups of foldable or telescopic clamping structures and combinations thereof. This can be adjusted appropriately according to the specific situation, which is easy for those skilled in the art to understand, and therefore, the detailed description is omitted here.

Cooling part

As shown in fig. 1, the cooling portion 70 is connected to the forming portion 20, fixed on one side of the frame portion 10, and provides a cooling tank for circulating cooling liquid, and a connecting duct for connecting with the forming portion 20, and the specific design of the cooling tank and the cooling duct can be adjusted according to specific situations, which is easy for those skilled in the art to understand, and therefore, the detailed description is omitted here.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make possible variations and modifications of the present invention using the methods and techniques disclosed above without departing from the spirit and scope of the present invention, and therefore, all changes and modifications that can be made to the above embodiments by the principles of the present invention shall fall within the scope of the present invention.

Claims

1. The laser 3D printing equipment comprises a rack part (10), a forming part (20), a gas protection part (30), a laser scanning part (50), a powder paving part (60) and a preheating part (40) capable of preheating forming powder, wherein the forming part (20) is an internal cavity which is relatively sealed and is formed by a plurality of parts fixed with the rack part (10), the laser 3D printing equipment is characterized in that the gas protection part (30) is externally arranged on the rack part (10) and is communicated with the forming part (20) in a circulating manner, the laser scanning part (50) is movably fixed along the outer side of the forming part (20), the preheating part (40) is fixed on the other side, opposite to the forming part (20), and is telescopically fixed in the rack part (10), the powder paving part (60) extends to the internal cavity of the forming part (20) for fixation, the laser scanning part (50) comprises a fixed substrate (51) connected with the frame part (10), a beam (52) fixed with the fixed substrate (51), and a vibrating mirror (53) movably fixed on the beam (52) under the drive of a driving component (54), at least two molding stations are arranged in the molding part (20), two adjacent molding stations in the molding stations are arranged at equal intervals, the preheating part (40) comprises a heating partition plate (41) tightly attached to the molding part (20) for fixing, and a heating component (45) attached to the heating partition plate (41) for fixing, the heat is continuously heated by the heating component (45) and is conducted to the molding part (20) through the heating partition plate (41), the molding part (20) comprises a molding substrate (21), and a molding component (22), a cooling component (24) and a lens (25) fixed on the molding substrate (21), the gas access assembly (23) is used for being communicated with protective gas, the gas access assembly (23) further comprises a blowing flange (231) fixed on the forming base plate (21), the side face of the end, parallel to and opposite to the lens (25), of the blowing flange (231) is provided with a blowing hole (2331), the blowing hole (2331) and the lens (25) are arranged in a staggered mode in different angles, the heating assembly (45) comprises at least one heating plate (452) which can be movably assembled, the heating plate (452) can be freely assembled and combined to form a continuous and/or intermittent heating area, the heating plate (452) is uniform in shape, is made of materials with different heat conduction coefficients, and can be arranged on the heating assembly 45 in a replaceable mode.

2. The 3D printing apparatus according to claim 1, further comprising a cooling portion (70) communicating with the molding portion (20) and fixed to a side of the frame portion (10), including a cooling tank and a communication duct.

3. The 3D printing apparatus according to claim 1, wherein the frame portion (10) comprises a fixed frame (11) for supporting and fixing other components, and a lifting device (12) for adjusting a molding height, wherein the lifting device (12) is fixed inside a frame of the frame portion (10) in a vertically up-down telescopic arrangement from a bottom end upward.

4. The 3D printing apparatus according to claim 3, wherein the fixing frame (11) includes a forming plate (111), a heating plate (112), and a support plate (114), and a skirt plate (113) fixed to an outer circumferential surface of the frame portion (10), wherein the skirt plate (113) is fixed to the forming plate (111) and the heating plate (112) with a gap therebetween.

5. 3D printing device according to claim 1, wherein the gas shield part (30) comprises an atmosphere shield device (31) and an air filter device (32) in circulating communication with the forming part (20), the atmosphere shield device (31) being arranged outside the frame part (10) separately from the air filter device (32).

6. The 3D printing apparatus according to claim 5, wherein the driving assembly (54) comprises a through beam (52), a ball screw (541) extending and fixed along the width direction of the fixed substrate (51), and a motor (542) providing driving power, wherein the motor (542) is fixed on the end side surface of the fixed substrate (51) in the width direction, connected with the ball screw (541), and fixed in an engagement way perpendicular to the beam (52).

7. The 3D printing device according to claim 6, wherein the galvanometers (53) are at least two, respectively arranged on both sides of the cross beam (52).

8. The 3D printing apparatus according to claim 1, wherein the powder spreading part (60) comprises a powder tank (61) fixed higher than the frame part (10), a powder spreading device (62) extending to the inside of the molding part (20), fixed to the bottom side of the frame part (10), a recovery tank (63) communicated with the bottom end of the forming part (20) through a recovery pipe (64), and a sealing device (65) which is matched with the frame part (10) and keeps the molding powder sealed in the molding process and a powder collecting device (66) which is used for collecting the molding powder leaked in the processing process to form secondary sealing, wherein the sealing device (65) is arranged between the forming part (20), the preheating part (40) and the frame part (10), the powder collecting device (66) is sealingly connected against the frame part (10) at a distance from the sealing device (65).

9. The 3D printing apparatus according to claim 8, wherein the powder collecting device (66) comprises a sealing rubber strip (661) hermetically fixed to the frame portion (10), and a powder collecting box (662) for collecting the molded powder, wherein the powder collecting box (662) is an open sealed accommodating cavity, and one end of the sealing rubber strip (661) is sealed and the other end of the sealing rubber strip (661) is open and is connected to the inside of the powder collecting box (662).