CN109663919B

CN109663919B - Multi-material part 3D printer and printing method thereof

Info

Publication number: CN109663919B
Application number: CN201910152410.0A
Authority: CN
Inventors: 吴伟辉; 霍启乐; 黄长征
Original assignee: Shaoguan University
Current assignee: Shaoguan University
Priority date: 2019-02-28
Filing date: 2019-02-28
Publication date: 2023-08-15
Anticipated expiration: 2039-02-28
Also published as: CN109663919A

Abstract

The invention relates to a multi-material part 3D printer which comprises a powder supply device, a residual powder removing device, a forming device and a control device. The powder supply device comprises a powder spreading box, a scraping plate, a plurality of quantitative powder supply funnels, a powder supply pipe and the like. The residual powder removing device comprises a first dust collection head, a second dust collection head and the like. The first dust collection head is fixed at the bottom of the side wall of the powder paving box, which is close to the powder paving platform, and is slightly higher than the powder paving platform; the second dust collection head is fixed at the top of the side wall of the powder paving box, which is far away from the powder paving platform. Compared with the prior art, the multi-material part 3D printer provided by the invention has the advantages that the first dust collection head and the second dust collection head are arranged on the powder spreading box, and the third dust collection head and the dust blowing head which are specially used for removing dust of the powder spreading box are arranged, so that powder spreading and residual powder removal on the powder spreading platform are sequentially completed, the fact that the residual powder of the last powder spreading is not mixed in the next powder spreading process is ensured, the impurity of components of each material area of the multi-material part is avoided, and the printing of the multi-material part is realized.

Description

Multi-material part 3D printer and printing method thereof

Technical Field

The invention relates to the field of 3D printing, in particular to a multi-material part 3D printer and a printing method thereof.

Background

Currently, laser 3D printing techniques based on the powder bed fusion principle mainly include laser selective fusion techniques (Selective Laser Melting, SLM), selective laser sintering techniques (Selective Laser Sintering, SLS), and the like. Such techniques typically employ a squeegee or roller to lay the powder layer-by-layer in a forming zone, then a laser beam is used to selectively melt or sinter the powder in the forming zone to solidify it, and then the next layer of powder is laid down and then solidified, so that the endless loop builds up layer-by-layer into a three-dimensional solid body. In the forming process, besides being used for forming the part, the powder is deposited on the lifting platform, and also plays a role of filling the powder on the lifting platform to provide powder support and even part support for the laying of the next layer of powder.

After the above 3D printing technology melts or sinters the powder in the forming area each time, it is difficult to effectively clean and recover the powder outside the selected area and input new heterogeneous materials, so in the conventional two technologies, only one material (single component material, alloy, coating powder, etc.) is generally used in one 3D printing process, it is difficult to obtain multi-material parts with different materials flexibly arranged in the same layer, and printing of the multi-material parts cannot be achieved. While in practice most parts or products are made of a variety of materials. The main reason why the multi-material 3D printing cannot be realized is that after each melting or sintering, different kinds of powder exist in a forming area, if the multi-material part 3D printing needs to be spread from the same place based on the powder bed melting principle, the excessive powder which prevents the multi-material part from being formed in the forming process cannot be removed, and the excessive powder comprises: the powder is adhered to the powder supply device or the powder spreading public channel to generate dust polluted by materials, different kinds of powder outside a selected area, powder which is not cleaned up during laser forming of different areas of the same forming layer and powder which is not cleaned up during laser forming of different materials are adopted by adjacent forming layers, and the different kinds of powder are easy to form the part and are mixed with impurities of different materials or cause printing failure.

Disclosure of Invention

Based on the above, an object of the present invention is to provide a 3D printer capable of realizing a multi-material part and a printing method thereof, so as to realize 3D printing of the multi-material part.

The invention solves the technical problems by adopting the scheme that:

the invention relates to a multi-material part 3D printer which comprises a forming device, a powder supply device, a residual powder removing device and a control device;

the forming device comprises a forming chamber, a laser scanning head, a forming cylinder body and a lifting table, wherein the forming cylinder body and the lifting table are positioned in a cavity of the forming chamber, the laser scanning head is positioned right above the lifting table, and the lifting table is positioned in the forming cylinder body and matched with the forming cylinder body and can do lifting motion along the inner wall of the forming cylinder body;

the powder supply device comprises a powder spreading box, a scraping plate, a plurality of quantitative powder supply funnels and powder supply pipes, wherein the quantity of the powder supply pipes is the same as that of the quantitative powder supply funnels; the quantitative powder supply funnel is positioned above the outside of the forming chamber, and the powder feeding pipe and the powder spreading box are positioned in the forming chamber; the powder spreading box is positioned above the forming cylinder body and below each powder feeding pipe and can slide left and right between the forming cylinder body and each powder feeding pipe along the horizontal direction; the bottom of the quantitative powder supply funnel is connected with the powder feeding pipe through a pipeline; the scraping plate is fixed at the bottom of the left side of the powder paving box;

The residual powder removing device comprises a first dust collection head, a second dust collection head, a third dust collection head, a dust blowing head, a dust collector, a filter, a fan and a plurality of pipelines;

the first dust collection head is fixed at the bottom of the right side wall of the powder paving box and slightly higher than the plane height of the top of the forming cylinder body; the second dust collection head is fixed at the top of the left side wall of the powder paving box; the dust blowing head and the third dust collection head are arranged on the left side wall of the forming chamber far away from the forming cylinder body, and the dust blowing head and the third dust collection head are distributed on the same straight line along the vertical direction; the first dust collection head, the second dust collection head and the third dust collection head are sequentially connected with the dust collector and the air inlet of the fan through pipelines, and the dust blowing head is connected with the air outlet of the fan through a pipeline; the filter is positioned between the integrator and the fan;

the control device controls the work of the powder supply device, the residual powder removing device and the forming device.

Further, the powder spreading box comprises a motor and a powder spreading box powder bearing plate; the motor is arranged on the side wall of the other side of the powder paving box, which is opposite to the connecting block of the powder paving box; the powder-spreading box powder-bearing plate is arranged in the powder-spreading box and is connected with the motor to realize rotation.

Further, the residual powder removing device further comprises a four-way valve, a multi-way valve and a plurality of electric control valves; the interfaces of the four-way valve are respectively connected with the first dust collection head, the second dust collection head, the third dust collection head and the dust collector through pipelines; the plurality of electric control valves comprise a first electric control valve, a second electric control valve, a third electric control valve, a fourth electric control valve, a fifth electric control valve and a powder cleaning electric control valve of the powder feeding pipe; the first electric control valve is arranged on a pipeline between the first dust collection head and the four-way valve, the second electric control valve is arranged on a pipeline between the second dust collection head and the four-way valve, and the third electric control valve is arranged on a pipeline between the third dust collection head and the four-way valve; the multi-way valve comprises an input interface and at least more than 3 output interfaces; the input interface is connected with the air outlet of the fan through a pipeline; the output interface is connected with the forming chamber through pipelines, and the fourth electric control valve, the fifth electric control valve and the powder cleaning electric control valve of the powder feeding pipe are arranged on the pipelines.

Further, the lower part of the quantitative powder supply funnel is provided with a three-way valve; the first port of the three-way valve is connected with the quantitative powder supply funnel, the second port is connected with the powder feeding pipe through a pipeline, and the third port is connected with the multi-way valve through a pipeline; the number of the powder cleaning electric control valves of the powder feeding pipe is the same as that of the quantitative powder feeding hoppers, and the powder feeding pipe is arranged on a pipeline connected with the three-way valve and the multi-way valve.

Further, the residual powder removing mechanism further comprises an electric control frequency converter; the electric control frequency converter is controlled by a control device; the electric control frequency converter adjusts the running state of the fan according to the frequency parameter transmitted by the control device, and then controllable air flow is formed.

Further, the device also comprises a residual powder storage device, wherein the residual powder storage device comprises a powder recovery box, a powder tank and a switch valve; the powder recovery box is embedded between the forming cylinder body and the side wall of the forming chamber without gaps, and gradually transits from top to bottom from square to conical; the powder tank is connected with the bottom of the powder recovery box; the switch valve is arranged between the powder tank and the powder recovery box.

Further, the powder supply device also comprises a powder box moving mechanism;

the powder box spreading moving mechanism is arranged on the outer wall of the forming chamber and comprises a synchronous belt type linear module, a guide rail sliding block, a powder box spreading connecting block and a limit proximity switch combination; a stepping motor is used for driving the synchronous belt to rotate in the synchronous belt type linear module; the guide rail sliding block is fixed on the linear module synchronous belt and moves along with the synchronous belt in a linear manner;

one end of the powder box connecting block is fixed with the guide rail sliding block, the other end of the powder box connecting block is fixed with the powder box, and the powder box moves along the direction parallel to the guide rail;

The proximity switch combination comprises a proximity switch, a proximity switch induction iron and a proximity switch installation guide rail; the proximity switch mounting guide rail is fixed on the outer wall of the forming chamber and is slightly lower than the lower part of the linear module; the proximity switch induction iron is arranged on the powder box connection block; the proximity switches are arranged on the proximity switch guide rail, and are respectively positioned at the corresponding positions of the dust blowing head, the powder feeding pipe made of various materials and the residual powder recycling box on the side wall of one side of the forming chamber.

The invention also provides a 3D printing method of the multi-material part, which comprises the following steps:

s1: providing a multi-material part, wherein each layer sheet comprises at least one material area, and if a plurality of material areas exist, the material compositions of the material areas are different; the 3D printing process of the multi-material part is controlled by a control device to run; respectively placing a plurality of powder materials into different powder supply hoppers;

s2: the powder spreading platform descends by a layer thickness distance;

s3: the control device controls the powder spreading box, the first dust collection head, the second dust collection head and the scraping plate which are arranged on the powder spreading box to translate to the position right below the powder feeding pipe corresponding to the material required by the current printing according to the type of the material required by the current printing material area, and controls the powder material to quantitatively fall into the powder spreading box;

S4: judging whether the powder material printed next time is the same as the current time;

(1) If the powder feeding channels are different, the powder laying box moves for a certain distance, a second dust collection head at one side of the powder laying box is aligned to the powder feeding pipe, a fan is started, air flow is input from a pipeline communicated with the powder feeding pipe, residual powder in the powder feeding channel below the corresponding powder feeding funnel is blown out, the second dust collection head is synchronously operated, the powder adhered in the powder feeding channel and the powder feeding pipe is adsorbed and recovered completely, and the fan is stopped; the powder spreading box moves to the upper part of the forming cylinder body with the powder, and opens the powder bearing plate of the powder spreading box to enable the powder to leak to the lifting platform, the scraping plate then arranges the powder to the lifting platform, meanwhile, the powder spreading box continues to translate to the upper part of the powder recovery box, and the redundant powder is dumped into the residual powder recovery box; the control device directs the laser beam to selectively melt or sinter the powder material according to the scanning data of the current printing material area through the laser scanning head;

the control device executes the residual powder removing program because the next printing material is different from the current printing material; the powder spreading box starts to return above the residual powder recovery box, when the powder spreading box returns to a certain distance from the forming area, the fan is started, and the first dust collection head sucks residual powder on the top of the forming cylinder body and the lifting table; when the powder spreading box moves to the end of the forming chamber along the return direction, namely the powder spreading box is opposite to the upper part of the third dust collection head and opposite to the lower part of the dust blowing head, the fan continues to operate, the first dust collection head is closed, the third dust collection head is opened, and the air flow after dust collection and filtration synchronously flows to the dust blowing head, so that dust collection and dust blowing are combined, the powder bonded on the powder spreading box, the first dust collection head and the second dust collection head is removed completely, the fan is stopped, the powder spreading box powder bearing plate is closed, the printing residual powder removing procedure is finished, and the printing is finished;

(2) If the powder is the same, the powder spreading box moves to the upper part of the forming cylinder body with the powder carried by the powder spreading box, the powder bearing plate of the powder spreading box is opened to enable the powder to be leaked down to the lifting table, the powder is arranged on the lifting table by the scraping plate, meanwhile, the powder spreading box moves to the upper part of the powder recovery box, the redundant powder is poured into the residual powder recovery box, and then the powder bearing plate of the powder spreading box is closed; the control device directs the laser beam to selectively melt or sinter the powder material according to the scanning data of the current printing material area through the laser scanning head, and the residual powder cleaning program is not executed because the next printing material is the same as the current printing material, and the printing is finished;

in the residual powder adsorption recovery cleaning process, the sucked dust is filtered by a cyclone dust collector and a filter, wherein the powder filtered by the cyclone dust collector is collected by a dust collecting barrel; in the running process of the fan, the electric control frequency converter is controlled by the control device, so that the power frequency of the fan is changed, and the proper air inlet flow is realized;

s5: judging whether the current layer is printed, if not, repeating the steps S3-S5; if the current layer is finished and is not the last layer, repeating the steps S2 to S5; if the printing is finished and the current layer is the last layer, the printing of the multi-material part is finished.

Compared with the prior art, the residual powder clearing method for the 3D printing of the multi-material part determines whether to clear the residual powder between two printing by judging whether the powder used for the continuous printing is the same or not, on one hand, ensures that the residual powder printed at the time is not mixed in the powder printed at the next time, can adopt more than two materials for forming in the same layer, can also adopt different materials for forming in different layers, and realizes the printing of the multi-material part; on the other hand, the powder used for printing is not cleaned only when the powder used for printing is different in the front and back, and is not cleaned when the powder is the same, so that the time is saved.

For a better understanding and implementation, the present invention is described in detail below with reference to the drawings.

Drawings

FIG. 1 is a schematic diagram of a 3D printer for multi-material parts according to the present invention;

FIG. 2 is a two-dimensional schematic view of the structure of the powder spreading box according to the invention;

FIG. 3 is a three-dimensional schematic view of the structure of the powder spreading box according to the invention;

FIG. 4 is a front view of the structure of the compact moving mechanism of the present invention;

FIG. 5 is a side view of the construction of the compact moving mechanism of the present invention;

FIG. 6 is a schematic illustration of a profiled ply material distribution of a part according to an embodiment of the present invention;

FIG. 7 is a schematic representation of the distribution of material from the next formed ply adjacent to the formed ply of FIG. 6 in accordance with the present invention.

Detailed Description

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.

According to the multi-material part 3D printer, whether the powder used for next printing is the same as the powder used for current printing or not is judged, if so, the next printing is directly carried out, and if not, the residual powder is removed and then the next printing is carried out, so that the technical problem that mixed powder is mixed in the multi-material printing is solved, and the 3D printing of the multi-material part is realized.

Please refer to fig. 1, which is a schematic diagram of a 3D printer for multi-material parts according to the present invention. The multi-material 3D printer comprises a forming device, a powder supply device, a residual powder removing device and a control device. The control device controls the forming device, the powder supply device and the residual powder removing device to work.

The forming device comprises a forming chamber 26, a laser scanning head 25 fixed on the inner wall of the top of the forming chamber 26, a forming cylinder 27 and a lifting table 29 positioned in the cavity of the forming chamber 26. The laser scanning head is positioned right above the lifting table 29, receives the instruction of the control device, and melts or sinters the powder on the lifting table 29 according to the pattern scanning data. The lifting table 29 is located inside the forming cylinder 27, and is matched with the forming cylinder 27 to perform lifting movement along the inner wall of the forming cylinder 27. Along with the 3D printing process, the lifting table 29 receives the instruction of the control device, and continuously adjusts the height of the lifting table.

The powder supply device comprises a plurality of quantitative powder supply funnels, powder supply pipes (15/17/19/21) which correspond to the quantitative powder supply funnels and have the same quantity, a powder paving box 23 and a scraping plate 34. The powder supply funnel is positioned above the forming chamber 26, and the powder feeding pipe (15/17/19/21), the powder paving box 23 and the scraping plate 34 are positioned in the cavity of the forming chamber 26. The powder spreading box 23 is positioned above the forming cylinder 27 and below each powder feeding pipe (15/17/19/21), and can slide left and right between the forming cylinder 27 and each powder feeding pipe (15/17/19/21) along the horizontal direction. The bottom of the powder supply funnel is connected with the powder feeding pipe (15/17/19/21) through a pipeline. As shown in fig. 2 and 3, the upper and lower surfaces of the powder paving box 23 are both opened, and include a powder bearing plate 231 and a motor 232. Specifically, the upper surface of the powder spreading box 23 is flush with the bottom of the powder feeding pipe (15/17/19/21) or slightly provided with a gap; the powder bearing plate 231 is positioned inside the powder paving box 23 and can rotate along with the motor 232, and is used for bearing and unloading powder flowing out of the powder conveying pipe (15/17/19/21). The powder bearing plate 231 receives powder from the powder feeding pipe (15/17/19/21) from the upper surface opening, and after the motor 232 drives the powder bearing plate 231 to rotate, the powder leaks out from the lower surface opening onto the lifting table 29. The scraping plate 34 is fixed at the bottom of the left side wall of the powder paving box 23, and is used for scraping the powder on the lifting table 29.

The residual powder storage device comprises a residual powder recovery box 28, a powder tank 31 and a switch valve 30. The powder spreading box 23 advances to the upper part of the residual powder recovery box 28 after the powder is spread on the lifting table 29, and the scraper 34 drives the residual powder to fall into the residual powder recovery box 28. The residual powder recovery box 28 is embedded between the forming cylinder 27 and the side wall of the forming chamber 26 without gaps, and gradually transits from square to conical from top to bottom. The powder tank 31 is located at the bottom of the residual powder recovery tank 28. The switch valve 30 is located between the residual powder recycling bin 28 and the powder tank 31, and is used for controlling powder to fall into the powder tank 31 from the residual powder recycling bin 28. When the switch valve 30 is opened, the residual powder can naturally fall into the powder tank under the action of gravity through the residual powder recovery box; when the switch valve 30 is closed, the residual powder falls into the residual powder recovery box 28 and does not fall into the powder tank 31, so that the powder tank can be replaced when the residual powder is filled in the powder tank. The powder pot 31 and the on-off valve 30 are located outside the molding chamber 26.

The control device controls the operation of the laser scanning head 25 and the lifting table 29 in the forming device; the control device also controls the work of a powder supply funnel in the powder supply device; the control device also controls the work of the residual powder removing device.

The residual powder removing device comprises a first dust collection head 24, a second dust collection head 22, a third dust collection head 35, a dust blowing head 13, a fan 1, a cyclone dust collector 42, a filter 2, a four-way valve 40, a multi-way valve 5, an electric control frequency converter, a plurality of electric control valves and a powder spreading box moving mechanism. The number of the plurality of electric control valves is equal to the number of the powder supply hopper plus the number of all dust collection heads and the number of the dust blowing heads plus one. The fan 1, the electric control frequency converter and the electric control valve are controlled by the control device. The first dust collection head 24, the second dust collection head 22, the third dust collection head 35 and the dust blowing head 13 are positioned in the cavity of the forming chamber 26; the fan 1, the cyclone dust collector 42, the filter 2, the electric control frequency converter and the powder spreading box moving mechanism are positioned outside the forming chamber 26.

The first dust collection head 24 is fixed on the right side wall of the powder paving box 23, and an opening of the first dust collection head is flush with the bottom of the powder paving box 23 and slightly higher than the top plane height of the forming cylinder 27, so as to suck residual powder of the lifting table 29. The second dust collection head 22 is fixed on the left side of the powder spreading box 23, and an opening of the second dust collection head is flush with the top of the powder spreading box 23 and is used for sucking away residual powder in the powder conveying pipe (15/17/19/21) and a pipeline connected with the powder conveying pipe (15/17/19/21).

The dust blowing head 13 and the third dust collection head 35 are arranged on the left side wall of the forming chamber 26 far away from the forming cylinder 27; the dust blowing heads 13 and the third dust collection heads 35 are distributed on the same straight line along the vertical direction. The third dust collection head 35 is used for sucking off the residual powder on the powder spreading box 23, the scraping plate 34 fixed on the powder spreading box, the first dust collection head 24 and the second dust collection head 22. The dust blowing head 13 is used for blowing off residual powder on the powder paving box 23, the scraping plate 34, the powder bearing plate 232, the first dust collection head 24 and the second dust collection head 22 which are fixed on the powder paving box.

The four-way valve 40 is connected with the first dust collection head 24, the second dust collection head 22, the third dust collection head 35 and the dust collector 41 through pipelines respectively.

The plurality of electric control valves comprise a first electric control valve 38, a second electric control valve 3, a third electric control valve 4, a fourth electric control valve 6, a fifth electric control valve 7 and a powder feeding pipe powder cleaning electric control valve (8/9/10/11). The first electrically controlled valve 38 is installed on a pipeline between the first dust collection head 24 and the four-way valve 40, the second electrically controlled valve 3 is installed on a pipeline between the second dust collection head 22 and the four-way valve 40, and the third electrically controlled valve 4 is installed on a pipeline between the third dust collection head 35 and the four-way valve 40. One interface of the cyclone dust collector 42 is connected with the four-way valve 40 through a pipeline, and the other interface is connected with the air inlet of the filter 2; the air outlet of the filter 2 is connected with the air inlet of the fan 1; that is, the fan 1, the filter 2 and the cyclone dust collector 42 can form a controllable airflow passage with the first dust collection head 24, the second dust collection head 22 and the third dust collection head 35 to lead the airflow to be conducted.

Specifically, when the pipe connected to the first dust collection head 24 passes through the forming chamber, it is connected to one end of the connector 36 on the side wall of the forming chamber, and the other end of the connector 36 is connected to the first electrically controlled valve 38 through the pipe. When the pipeline connected with the second dust collection head 22 passes through the forming chamber, the pipeline is connected to one end of a connector 37 on the side wall of the forming chamber, and the other end of the connector 37 is connected with the second electric control valve 3 through the pipeline. When the pipeline connected with the third dust collection head 35 passes through the forming chamber, the pipeline is connected to one end of a connector 39 on the side wall of the forming chamber, and the other end of the connector 39 is connected with the third electric control valve 4 through the pipeline. The three pipelines connected with the three electric control valves are respectively connected with the three through holes of the four-way valve 40, and the last through hole of the four-way valve is communicated with the inlet of the cyclone dust collector 42 through one pipeline. The dust collection barrel 41 is located at the bottom of the cyclone dust collector 42 to hold the residual powder in the forming chamber 26 sucked by the dust suction head. The filter 2 is arranged between the outlet of the cyclone dust collector 42 and the air inlet of the fan 1, so as to avoid the fan failure caused by the powder being sucked into the fan 1.

The fourth electrically controlled valve 6 is arranged between one port of the multi-way valve 5 and one port of a joint 12 on the side wall of the forming chamber, and the other port of the joint 12 is connected with a dust blowing head 13 through a pipeline.

The multi-way valve 5 comprises at least more than 3 input interfaces, wherein the input interfaces are connected with the air outlet of the fan 1 through pipelines; the output interface is connected with the forming chamber 26 through pipelines, and the fifth electric control valve 7 and the powder cleaning electric control valve of the powder feeding pipe are arranged on the pipelines. I.e. the forming chamber 26 forms a controllable passage with the fan 1 for the air flow to be conducted.

Specifically, the dust blowing head 13 located in the cavity of the forming chamber 26 is connected with the air outlet of the fan 1 outside the forming chamber 26 through a pipeline, so as to blow off residual powder through the air outlet of the fan 1; the bottom of the powder supply funnel is provided with a three-way valve (14/16/18/20), a first port of the three-way valve (14/16/18/20) is connected with the quantitative powder supply funnel, a second port of the three-way valve is connected with a powder feeding pipe (15/17/19/21) through a pipeline, and a third port of the three-way valve is connected with a multi-way valve 5 through a pipeline, so that residual powder adhered in the three-way valve (14/16/18/20) and the powder feeding pipe (15/17/19/21) can be blown away through the air outlet of the fan 1; a pipeline is led out from the cavity of the forming chamber 26 and is directly connected with the multi-way valve 5 through the fifth electric control valve 7, so that the air flow of the fan is led back to the forming chamber 26 to prevent the loss of protective gas when the powder is not required to be blown and removed.

Referring to fig. 4 and 5, the powder feeding device further includes a powder spreading box moving mechanism.

The powder box moving mechanism is arranged on the rear wall plate of the forming chamber and comprises a synchronous belt type linear module 43, a powder box connecting block 44, a limit proximity switch combination and an airtight cover 49. The synchronous belt type linear module 43 drives the synchronous belt to rotate by a stepping motor 45. The rail slider 431 fixed to the timing belt type linear module moves linearly along with the timing belt. One end of the powder box laying connecting block 44 is fixed with the guide rail sliding block 431, and the other end is fixed with the powder box laying 23, so that the powder box laying 23 can be driven along the direction parallel to the synchronous belt type linear module 43. The airtight cover 49 and the outer wall of the forming chamber 26 jointly cover the synchronous belt type linear module 43, the powder box laying connecting block 44 and the limit proximity switch combination so as to prevent the protective gas from leaking from the forming chamber.

The proximity switch assembly includes a proximity switch 46, a proximity switch sensing iron 47, and a proximity switch mounting rail 48. The proximity switch mounting rail 48 is fixed to the rear wall plate of the forming chamber slightly below the timing belt type linear module 43. The proximity switch sensing iron 47 is mounted on the compact connection block 44. The proximity switches 46 are arranged on the proximity switch guide rail 48 and are respectively positioned at the positions of the dust blowing head 13, the third dust collection head 35, the powder feeding pipe (15/17/19/21) and the residual powder recycling bin 28 close to the side wall of the forming chamber 26. The stepper motor 45 operates to drive the guide rail slider 431, i.e. to drive the powder box connection block 44 to move on the timing belt type linear module 43, i.e. to drive the powder box 23 and the proximity switch induction iron 47 to move. When the proximity switch induction iron 47 moves to a proximity switch corresponding to the positions of a plurality of powder feeding pipes (15/17/19/21), a signal is transmitted to the control device, the control device commands the stepping motor 45 to stop running, the powder spreading box 23 stops below the corresponding powder feeding pipe, and after the powder spreading box 23 receives the quantitative powder, the control device commands the stepping motor 45 to run again, and the powder spreading box 23 continues to move forwards; the powder spreading box moves to the upper part of the forming cylinder 27 with the powder, the powder bearing plate 231 of the powder spreading box is opened to enable the powder to leak down to the lifting table 29, the powder is arranged on the lifting table 29 by the scraping plate 34, meanwhile, the powder spreading box continues to translate to the upper part of the powder recovery box 28, and the redundant powder is dumped into the residual powder recovery box 28; the 3D printer control directs the laser beam through the laser scanning head 25 to selectively melt or sinter the powder material according to the current print material area scan data. If the powder used for the next printing is different from the powder used for the current printing, executing a residual powder cleaning program: the control device sends a command to the stepper motor 45, the powder spreading box 23 starts to return above the residual powder recovery box 28, and when the powder spreading box 23 returns to a certain distance from the forming area, the fan 1 is started, and the first dust suction head 24 sucks residual powder on the top of the forming cylinder 27 and the lifting table 29. By changing the power frequency of the electric control frequency converter for controlling the rotating speed of the fan 1 and the rotating speed of the stepping motor 45, the air inlet flow of the first dust collection head 24 and the traveling speed of the powder spreading box 23 can be controlled, so that powder with one or a plurality of layers of thickness outside the current printed material area and dust scattered on the top of the forming cylinder 27 and the lifting table 29 are adsorbed, recovered and removed completely, and the air flow after dust collection and filtration flows back to the area without dust generation in the forming chamber. When the powder laying box 23 moves to the end of the forming chamber 26 along the return direction, namely, the powder laying box 23 moves to a proximity switch at the dust blowing head 13, the control device receives a signal of the proximity switch, and sends a command to the stepping motor 45, and the stepping motor stops working, and at the moment, the powder laying box 23 is opposite to the upper part of the third dust collection head 35 and opposite to the lower part of the dust blowing head 13. The fan 1 is controlled to have proper air inlet flow through the electric control frequency converter, the third electric control valve 4 and the fourth electric control valve 6 are controlled to be opened through the control device, and the other electric control valves are controlled to be closed, so that the third dust collection head 35 starts dust collection, air flow after dust collection and filtration synchronously flows to the dust blowing head 13, and powder adhered on the powder paving box 23, the first dust collection head 24 and the second dust collection head 22 is removed completely through the air blowing cleaning and negative pressure adsorption modes. The fan 1 is stopped, the powder bearing plate 231 of the powder spreading box is closed, and the printing residual powder removing program is finished.

s2: the powder spreading platform descends by a layer thickness distance;

s3: the control device enables the powder spreading box 23, the first dust collection head 24, the second dust collection head 22 and the scraping plate 34 arranged on the powder spreading box 23 to translate to the position right below the powder feeding tube (15, 17, 19 or 21) corresponding to the material required by the current printing according to the type of the material required by the current printing material area, and controls the powder material to quantitatively fall into the powder spreading box 23;

s4: judging whether the powder material printed next time is the same as the current time or not:

(1) If the powder feeding device is different, the powder laying box 23 moves a certain distance, the second dust collection head 22 at one side of the powder laying box 23 is aligned with the powder feeding pipe, the fan 1 is started, air flow is input from a pipeline communicated with the corresponding powder feeding pipe, residual powder in a powder feeding channel below a corresponding powder feeding funnel is blown out, the second dust collection head 22 is synchronously operated, the powder adhered in the powder feeding channel and the powder feeding pipe is adsorbed and recovered completely, and the fan is stopped; the powder laying box 23 moves to the upper part of the forming cylinder 27 with the powder, the powder laying box powder bearing plate 231 is opened to enable the powder to be leaked down to the lifting table 29, the powder is arranged on the lifting table 29 by the scraping plate 34, meanwhile, the powder laying box 23 moves to the upper part of the powder recovery box 28, and the surplus powder is poured into the residual powder recovery box 28; the control device then directs the laser beam through the laser scanning head 25 to selectively melt or sinter the powder material according to the current printing material area scanning data;

The control device executes the residual powder removing program because the next printing material is different from the current printing material; the powder spreading box 23 starts to return above the residual powder recovery box 28, and when the powder spreading box 23 returns to a certain distance from the forming area, the first dust suction head 24 sucks residual powder on the top of the forming cylinder 27 and the lifting table 29; by controlling the air inlet flow of the first dust collection head 24 and the running speed of the powder spreading box 23, one or a plurality of layers of powder with thickness outside the current printed material area and dust scattered on the top of the forming cylinder 27 and the lifting table 29 can be adsorbed, recovered and removed completely, and the air flow after dust collection and filtration flows back to the area without dust generation in the forming chamber 26; when the powder spreading box 23 moves to the end of the forming chamber 26 along the return direction, namely the powder spreading box 23 is opposite to the upper part of the third dust collection head 35 and opposite to the lower part of the dust blowing head 13, the fan 1 is controlled to have proper air inlet flow through the electric control frequency converter, the third electric control valve 4 and the fourth electric control valve 6 are controlled to be opened through the control device, the other electric control valves are closed, the first dust collection head 24 is closed, the third dust collection head 35 starts dust collection, the air flow after dust collection and filtration synchronously flows to the dust blowing head 13, the powder adhered on the powder spreading box 23, the first dust collection head 24 and the second dust collection head 22 is removed completely through the air blowing cleaning and negative pressure adsorption modes, the fan 1 is stopped, the powder bearing plate 231 of the powder spreading box is closed, the printing residual powder cleaning procedure is finished, and the printing is finished;

(2) If the powder is the same, the powder laying box 23 moves to the upper part of the forming cylinder 27, the powder laying box powder bearing plate 231 is opened to enable the powder to be leaked to the lifting table 29, the scraping plate 34 is used for arranging the powder on the lifting table 29, meanwhile, the powder laying box 23 moves to the upper part of the powder recovery box 28, the redundant powder is poured into the residual powder recovery box 28 at one side of the powder laying platform, and then the powder laying box powder bearing plate 231 is closed; the control device directs the laser beam through the laser scanning head 25 to selectively melt or sinter the powder material according to the current printing material area scanning data;

and because the next printing material is the same as the current printing material, the residual powder removing program is not executed, and the printing is finished.

In the residual powder adsorption recovery cleaning process, the sucked dust is filtered by the cyclone dust collector 42 and the filter 2, wherein the powder filtered by the cyclone dust collector 42 is collected by the dust collecting barrel 41.

The printing method is specifically described below, and for convenience of explanation, the corresponding quantitative powder supply funnel, powder supply tube and powder supply tube cleaning electric control valve may be referred to as a first powder supply funnel, a first powder supply tube 21 and a first powder supply tube cleaning electric control valve 11, a second powder supply funnel, a second powder supply tube 19 and a second powder supply tube cleaning electric control valve 10, and so on. The thickness of the powder layer of each layer was assumed to be 20 μm. Before printing begins, all of the electrically controlled valves and the powder bearing plate 231 are in the closed state.

S1: providing a multi-material part, wherein each layer sheet comprises at least one material area, and if a plurality of material areas exist, the material compositions of the material areas are different; the 3D printing process of the multi-material part is controlled by a control device to run; 3D printing data of the multi-material part to be printed are imported to the 3D printer control device, wherein the data comprise geometric figure scanning data of each material area and material information. And respectively placing a plurality of powder materials into different powder supply hoppers, and arranging the powder required by the printing at the time to be loaded into the first powder supply hopper.

S2: the 3D printer control device controls the lifting table 29 to descend by 20 μm through an electric push rod.

S3: the 3D printer control device instructs the stepper motor 45 to operate, and drives the powder paving box 23 to move to the position below the first powder feeding pipe 21 to receive powder.

S4: the 3D printer control device judges whether the powder material required by the next printing is the same as the powder printed at the time.

If the residual powder is different, the 3D printer control device executes a residual powder removing program: the control device controls the stepping motor 45 to enable the second dust collection head 22 fixed on the powder paving box 23 to move below the first powder conveying pipe 21; simultaneously, the 3D printer control device controls the second electric control valve 3 and the first powder feeding pipe powder cleaning electric control valve 11 to be opened, other electric control valves are closed, and proper frequency is sent to an electric control frequency converter and the fan 1 is started; the air outlet of the fan 1 and the first powder feeding pipe 21 are connected through the opened first powder feeding pipe powder cleaning electric control valve 11, the opened fan 1 blows out residual powder in a pipeline connected with the first powder feeding pipe 21, meanwhile, the air inlet of the fan 1 and the second dust collection head 22 are connected through the opened second electric control valve 3, the second dust collection head 22 positioned below the first powder feeding pipe 21 sucks out the residual powder in the first powder feeding pipe 21, and the residual powder is conveyed to the cyclone dust collector 42 outside the forming chamber 26 through the pipeline; after the fan 1 is turned on for about 10s-60s, the fan 1 is turned off.

After the powder feeding pipe 21 and the residual powder in the pipeline connected with the powder feeding pipe are cleaned through blowing and sucking, the stepping motor 45 operates to drive the powder paving box 23 to move to the position above the lifting table 29, then the 3D printer control device commands the motor 232 in the powder paving box to rotate by an angle, the powder bearing plate 231 is opened, the powder falls on the lifting table 29, the scraping plate 34 fixed on the powder paving box 23 moves forwards along with the powder paving box 23, and the powder behind the powder paving box 23 is paved; the powder spreading box 23 continues to move forward to above the powder recovery box 41, and excessive powder falls into the powder recovery box 41 from the powder spreading box 23; the laser scanning head 25 selectively melts or sinters the laid powder for molding in accordance with the scanning data.

And the 3D printer control device continues to execute the residual powder removing program because the next printing material is different from the next printing material. After all the powder is discharged from the powder laying box 23, the powder returns to the upper part of the lifting table 29, and the first dust collection head 24 fixed at the bottom of the side surface of the powder laying box 23 also returns to the upper part of the lifting table 29, and at the moment, a layer of powder is formed on the upper part of the lifting table 29; the control device controls the first electric control valve 38 to be opened, the fifth electric control valve 7 to be opened, the rest electric control valves to be closed, and the fan 1 to be started; through the opened first and fifth electric control valves 38 and 7, an air flow channel is formed among the first dust collection head 24, the cyclone dust collector 42, the filter 2, the fan 1, the fifth electric control valve 7 and the forming chamber 26, and along with the return movement of the powder spreading box 23, the first dust collection head 24 sequentially sucks the residual powder above the lifting table 29 into the cyclone dust collector 42 outside the forming chamber 26 from front to back, and the filtered air flow containing the protective gas flows back to the forming chamber 26.

The powder spreading box 23 retreats to the upper part of the third dust collection head 35; the control device controls the third electric control valve 4 and the fourth electric control valve 6 to be opened, the other electric control valves are closed, and then the fan 1 is controlled to have proper air inlet flow through the electric control frequency converter; the air outlet of the fan 1 and the dust blowing head 13 are connected through the opened fourth electric control valve 6, the opened fan 1 blows off residual dust falling on the powder paving box 23 and the scraping plates 34, the first dust collection head 24 and the second dust collection head 22 fixed on the powder paving box, and meanwhile, the air inlet of the fan 1 and the third dust collection head 35 are connected through the opened third electric control valve 4, and the opened fan 1 sucks residual dust falling on the powder paving box 23 and the scraping plates 34, the first dust collection head 24 and the second dust collection head 22 fixed on the powder paving box into the cyclone dust collector 42 outside the forming chamber 26; after the fan 1 is started for about 10s-60s, the fan 1 and the powder bearing plate 231 of the powder spreading box are closed. The printing is completed.

If the powder is the same, the residual powder removing program is not carried out, the control device controls the stepping motor 45 to operate so as to drive the powder paving box 23 to move forward above the lifting table 29, the control device controls the motor 232 to rotate, the powder bearing plate 231 rotates by an angle, the powder bearing plate 231 is opened, powder falls onto the lifting table 29, and the scraping plate 34 fixed on the powder paving box 23 moves forward along with the powder paving box 23 so as to scrape the powder on the lifting table 29; the powder spreading box 23 continues to move forward to the position above the powder recovery box 41, excessive powder falls into the powder recovery box 41 from the opening of the lower surface of the powder spreading box 23, and then the powder bearing plate 231 of the powder spreading box is closed; the laser scanning head 25 selectively melts or sinters the laid powder for molding in accordance with the scanning data. The printing is completed.

S5: returning to the step S3 if printing of other areas on the same layer is needed according to the judgment of the control device, and circularly carrying out the steps S3 to S5 until all the printing of the layer is finished;

if the printing of the layer is completed and the layer is not the last layer, returning to the step S2, and printing the next layer. If the printing of the layer is finished and the layer is the last layer, the whole 3D printing process is finished.

It should be noted that, when steps S3 and S4 are circularly implemented, the powder feeding pipe and the powder feeding pipe powder cleaning electric control valve should be reasonably selected according to the type of the material used in the current printed material area, and are not limited by the above description of the "first powder feeding pipe 21" and the "first powder feeding pipe powder cleaning electric control valve 11".

Compared with the prior art, the multi-material part 3D printer sequentially completes the cleaning of the powder feeding pipe and the residual powder in the pipeline connected with the powder feeding pipe by arranging the residual powder cleaning device with the dust collecting heads and the dust blowing heads, the residual powder on the powder spreading platform, the scraping plate fixed on the powder spreading box, the residual powder of the first dust collecting head and the second dust collecting head, and the residual powder of the upper layer or the upper region are comprehensively cleaned, so that the residual powder of the upper layer or the upper region is not mixed in the powder of the lower layer or the lower region, the printing failure is avoided or the impurities are mixed in the part obtained by printing, and the pollution-free printing of the multi-material part is realized; judging whether the powder used in the next area is the same as all the powder printed at this time through the control device, avoiding the residual powder cleaning each time, and only cleaning the residual powder when the powder used in the next time is different from the powder used at this time, thereby saving the printing time; the powder storage device is arranged to store unused powder, so that the recycling of the powder is realized, and the cost is saved; the electric control frequency converter is used for controlling the opening and closing of the fan and different electric control valves, so that the operation of blowing out residual powder and the operation of absorbing the residual powder by negative pressure can be realized by one fan.

Example 1

The following describes a method for cleaning residual powder in 3D printing of a multi-material part and a working process of the device for cleaning residual powder in 3D printing of a multi-material part according to the present invention in detail with reference to an embodiment.

Assuming that a multi-material part 32 of 3 materials as shown in fig. 1 is to be printed, the laser selective melting technique is to be used for printing. Each shaping layer of the multi-material part 32 is made of more than one material, and each shaping layer can be divided into a plurality of material areas according to material types, and all material areas with the same material form a material model with the same material, for example, in this example, the multi-material part 32 can be made of a first material 321, a second material 322 and a third material 323, where the first material 321 is pure titanium, the second material 322 is bronze, and the third material 323 is 316L stainless steel. It should be noted that there may be only one material region in some shaping layers, two or even three material regions in some shaping layers, and that a material region may be a single continuous block region or may be composed of several small regions separated from each other. Let the first powder feeding tube 21 be dedicated to feeding pure titanium powder in this printing, the second powder feeding tube 19 be dedicated to feeding bronze powder, and the third powder feeding tube 17 be dedicated to feeding 316L stainless steel powder. The thickness of the powder layer was assumed to be 20. Mu.m. The 3D printing process provided with the multi-material part 32 is controlled by a laser selective melting 3D printer control device.

As shown in fig. 6 and 7, the working process of the multi-material part 3D printing process residual powder cleaning method and device of the present invention will be specifically described by taking the 3D printing process of the part including three material areas of the molding layer 50 and the next molding layer 51 adjacent to the molding layer 50 including two material areas as an example.

(1) The 3D printer control device imports 3D printing data of the multi-material part, wherein the data comprises geometric figure scanning data and material information of each material area;

(2) Lowering the forming platform by 20 mu m;

(3) Powder feeding, spreading, printing and residual powder removal of the pure titanium material region 50321 of the shaping layer 50 are performed:

as shown in fig. 1. The 3D printer control device moves the powder paving box 23 constructed by the powder paving box 23, the first dust collection head 24, the second dust collection head 22 and the scraping plate 34 to the position right below the first powder feeding pipe 21, and controls the first powder feeding funnel to feed quantitative pure titanium powder into the powder paving box 23 through the first powder feeding pipe 21.

The 3D printer control device judges that the next printing material area 50322 is made of bronze powder material different from the current printing material area, so that the powder laying box moves at a proper speed, when the second dust suction head 22 on one side of the powder laying box 23 is aligned to the first powder feeding pipe 21, the 3D printer control device firstly controls the second electric control valve 3 and the powder feeding pipe powder cleaning electric control valve 11 to be opened, other electric control valves are closed, then a proper fan 1 power frequency signal is sent to the electric control frequency converter, the filtered reflux air flow is blown into the powder feeding channel communicated with the first powder feeding pipe 21 from the powder feeding pipe powder cleaning electric control valve 11, residual powder in the powder feeding channel below the corresponding first powder feeding funnel is blown out, the second dust suction head 22 is synchronously operated, and the powder adhered in the powder feeding channel is adsorbed and recovered cleanly by proper suction force.

Then the fan 1 stops running, the stepping motor 45 runs to drive the powder paving box 23 to move to the position above the lifting table 29, then the 3D printer control device commands the motor 232 in the powder paving box to rotate by an angle, the powder bearing plate 231 is opened, powder falls on the lifting table 29, the scraper 34 fixed on the powder paving box 23 moves forwards along with the powder paving box 23, the powder behind the powder paving box 23 is paved, the redundant powder is poured into the residual powder recovery box 28 on the right side of the lifting table 29, and the residual powder flows into the powder tank 31 outside the forming chamber 26 through the switch valve 30.

After the powder material is spread, the 3D printer control device directs the laser beam through the laser scanning head 25 to selectively melt the powder material according to the geometric figure scanning data of the current printing material area.

Because the next printing material area 50322 adopts bronze powder materials different from the current printing material area, when the powder spreading box returns to a position which is 20-30mm away from the forming area, the 3D printer control device firstly controls the first electric control valve 38 and the fifth electric control valve 7 to be opened, the other electric control valves are closed, then the electric control frequency converter controls the fan 1 to have proper air inlet flow, and controls the motor of the powder spreading box moving mechanism to keep proper return speed, so that the first dust suction head 24 on one side of the powder spreading box 23 starts to work, and powder with the thickness of about 20-60 mu m below the first dust suction head 24 is sucked clean. Along with the backward movement of the powder spreading box 23, the first dust collection head 24 sequentially sucks the residual powder on the top of the forming cylinder body and above the lifting table 29 into the cyclone dust collector 42 outside the forming chamber 26 from front to back, most of the powder in the air flow is collected into the dust collection barrel 41, and the air flow with trace powder flows back to the region in the forming chamber 26 where no dust is generated after being filtered again by the filter 2 at the air outlet of the cyclone dust collector 42.

When the laying box 23 returns to the end of the powder feeding side of the forming chamber 26, a third dust suction head 35 and a dust blowing head 13 are arranged, the third dust suction head 35 faces the lower part of the laying box, and the dust blowing head 13 faces the upper part of the laying box. Because the next printing material area 50322 is made of bronze powder material different from the current printing material area, the 3D printer control device controls the third electric control valve 4 and the fourth electric control valve 6 to be opened, the other electric control valves are closed, then the fan 1 is controlled to have proper air inlet flow through the electric control frequency converter, and the motor 45 driving the powder spreading box moving mechanism is controlled to keep a stop state, and then the third dust suction head 35 and the dust blowing head 13 synchronously start to work: the air flow of the filtered reflux is blown out from the dust blowing head 13 through the fourth electric control valve 6, dust adhered on the powder spreading box is blown down and synchronously sucked by the third dust suction head 35. After the fan 1 is started for about 10s-60s, the fan 1 and the powder bearing plate 231 of the powder spreading box are closed.

In this way, the printing of the regions 50321 of pure titanium material of the shaping layer 50 is completed.

(4) Powder feeding, spreading, printing and residual powder removal of bronze material areas 50322 of the profiled layer 50 are performed:

the 3D printer control device moves the powder paving box 23 constructed by the powder paving box 23, the first dust collection head 24, the second dust collection head 22 and the scraping plate 34 to the position right below the second powder feeding pipe 19, and controls the external second powder feeding funnel to feed quantitative bronze powder into the powder paving box 23 through the second powder feeding pipe 19.

The 3D printer control device judges that the next printing material area 50323 is made of 316L stainless steel powder material different from the current printing material area, so that the powder laying box moves at a proper speed, when the second dust suction head 22 on one side of the powder laying box 23 is aligned to the first powder feeding pipe 21, the 3D printer control device firstly controls the second electric control valve 3 and the powder feeding pipe powder cleaning electric control valve 10 to be opened, the other electric control valves are closed, then a proper fan 1 power frequency signal is sent to the electric control frequency converter, the filtered reflux air flow is blown into the powder feeding channel communicated with the second powder feeding pipe 19 from the powder feeding pipe powder cleaning electric control valve 10, residual powder in the powder feeding channel below the corresponding second powder feeding funnel is blown out, and the second dust suction head 22 is synchronously operated, so that the powder adhered in the powder feeding channel is adsorbed and recovered cleanly by proper suction force.

Because the next printing material area 50323 adopts 316L stainless steel powder material different from the current printing material area 50322, the powder spreading box returns, when the powder spreading box returns to a position which is 20-30mm away from the forming area, the 3D printer control device firstly controls the first electric control valve 38 and the fifth electric control valve 7 to be opened, the other electric control valves are closed, then the electric control frequency converter is used for controlling the fan 1 to have proper air inlet flow, and the motor of the powder spreading box moving mechanism is controlled to keep proper return speed, so that the first dust collection head 24 on one side of the powder spreading box 23 starts to work, and powder with the thickness of about 20-60 mu m below the first dust collection head 24 is sucked cleanly;

when the laying box 23 returns to the end of the forming chamber 26, there are provided a third dust suction head 35 and a dust blowing head 13, the third dust suction head 35 facing the lower part of the laying box 23 and the dust blowing head 13 facing the upper part of the laying box 23. Because the next printing material area 50323 adopts 316L stainless steel powder material which is different from the current printing material area, the 3D printer control device controls the third electric control valve 4 and the fourth electric control valve 6 to be opened, the other electric control valves to be closed, then the electric control frequency converter controls the fan 1 to have proper air inlet flow, and controls the motor 45 of the powder box paving moving mechanism unit to keep a stop state, at the moment, the third dust suction head 35 and the dust blowing head 13 synchronously start to work, and the air filtered and reflowed flows through the fourth electric control valve 6 to be blown out from the dust blowing head 13, so that dust adhered on the powder box is blown down and synchronously sucked by the third dust suction head 35. After the fan 1 is started for about 10s-60s, the fan 1 and the powder bearing plate 231 of the powder spreading box are closed.

In this way, the printing of the bronze material region 50322 of the shaping layer 50 is completed.

(5) Powder supply, spreading, and residual powder removal of the 316L stainless steel material print material region 50323 of the shaping layer 50 were performed:

the 3D printer control device moves the powder paving box 23 constructed by the powder paving box 23, the first dust collection head 24, the second dust collection head 22 and the scraping plate 34 to the position right below the third powder feeding pipe 17, and controls the external corresponding powder feeding funnel to feed quantitative 316L stainless steel powder into the powder paving box 23 through the third powder feeding pipe 17.

The 3D printer control device determines that the next printing material area 51323 has the same material as the current printing material area,

the stepper motor 45 is thus operated to drive the laying box 23 to move to a position above the lifting table 29, then the 3D printer control device commands the motor 232 in the laying box to rotate by an angle, the powder bearing plate 231 is opened, powder falls onto the lifting table 29, the scraper 34 fixed on the laying box 23 moves forward along with the laying box 23, the powder behind the laying box 23 is laid flat, the excessive powder is poured into the residual powder recovery box 28 on the right side on the lifting table 29, the residual powder flows into the powder tank 31 outside the forming chamber 26 again through the switch valve 30, and then the powder bearing plate 231 of the laying box is closed.

Since the next print material area 51323 has the same material as the current print material area, the powder purge and recovery operation is not performed.

In this way, the printing of the 316L stainless steel material region 50323 of the shaping layer 50 is completed.

(6) The forming table 28 is lowered by 20 μm;

(7) Powder supply, spreading, and residual powder removal of the 316L stainless steel material region 51323 of the shaping layer 51 were performed:

the 3D printer control device moves the powder paving box constructed by the powder paving box 23, the first dust collection head 24, the second dust collection head 22 and the scraping plate 34 to the position right below the third powder feeding pipe 17, and controls the external third powder feeding funnel to feed quantitative 316L stainless steel powder into the powder paving box 23 through the third powder feeding pipe 17.

The 3D printer control device judges that the next printing material area 51321 adopts pure titanium powder material different from the current printing material area, so that the powder laying box 23 moves at a proper speed, when a second dust collection head 22 on one side of the powder laying box 23 is aligned to a third powder feeding pipe 17, the 3D printer control device firstly controls a second electric control valve 3 and a powder feeding pipe powder cleaning electric control valve 9 to be opened, other electric control valves are closed, then a proper fan 1 power frequency signal is sent to an electric control frequency converter, filtered reflux air flow is blown into a powder feeding channel communicated with the third powder feeding pipe 17 from the powder feeding pipe powder cleaning electric control valve 9, residual powder in the powder feeding channel below the corresponding third powder feeding funnel is blown out, and the second dust collection head 22 is synchronously enabled to work, and powder adhered in the powder feeding channel is adsorbed and recovered cleanly by proper suction.

Because the next printing material area 51322 adopts pure titanium powder material different from the current printing material area, the powder spreading box returns, when the powder spreading box returns to a position which is 20-30mm away from the forming area, the 3D printer control device firstly controls the first electric control valve 38 and the fifth electric control valve 7 to be opened, the rest electric control valves are closed, then the electric control frequency converter is used for controlling the fan 1 to have proper air inlet flow, and the motor of the powder spreading box moving mechanism keeps proper return speed, so that the first dust suction head 24 on one side of the powder spreading box 23 starts to work, and powder with the thickness of about 20-60 mu m below the first dust suction head 24 is sucked cleanly;

When the laying box 23 returns to the end of the left side of the forming chamber 26, there are provided a third dust-absorbing head 35 and a dust-blowing head 13, the third dust-absorbing head 35 facing the lower part of the laying box and the dust-blowing head 13 facing the upper part of the laying box. Because the next printing material area 51322 adopts pure titanium powder material different from the current printing material area, the 3D printer control device controls the third electric control valve 4 and the fourth electric control valve 6 to be opened, the other electric control valves are closed, then the fan 1 is controlled to have proper air inlet flow through the electric control frequency converter, and the motor of the powder box spreading moving mechanism is controlled to keep a staying state, at the moment, the third dust suction head 35 and the dust blowing head 13 synchronously start to work, and the air filtered and reflowed flows through the fourth electric control valve 6 to be blown out from the dust blowing head 13 to blow dust adhered on the powder box and synchronously sucked by the third dust suction head 35. After the fan 1 is started for about 10s-60s, the fan 1 and the powder bearing plate 231 of the powder spreading box are closed.

In this way, the printing work of the 316L stainless steel material region 51323 of the shaping layer 51 is completed.

(8) Powder supply, spreading and residual powder removal of the pure titanium material region 51321 of the shaping layer 51 are performed:

it is assumed that the 1 st material area printed on the next layer of the modeling layer 51 is made of a different material from the current printing material area. The printing process of the region is the same as the step (3) except that the region information of the next printing material judged by the control device of the 3D printing and the laser beam to be controlled selectively melt the powder material according to the geometric figure scanning data of the region of the printing material, and the rest processes are not repeated here.

Assuming that the material used in the 1 st material area printed on the next layer of the molding layer 51 is the same as the material area printed this time, the 3D printer control device moves the powder laying box 23 constructed by the powder laying box 23, the first dust collection head 24, the second dust collection head 22 and the scraping plate 34 to the position right below the first powder feeding tube 21, and controls the external corresponding powder feeding funnel to feed quantitative pure titanium powder into the powder laying box 23 through the first powder feeding tube 21. The 3D printer control device determines that the next printing material area and the current printing material area have the same material, so that the stepping motor 45 operates to drive the powder spreading box 23 to move to a position above the lifting table 29, then the 3D printer control device commands the motor 232 in the powder spreading box to rotate by an angle, the powder bearing plate 231 is opened, powder falls on the lifting table 29, the scraper 34 fixed on the powder spreading box 23 moves forwards along with the powder spreading box 23, the powder behind the powder spreading box 23 is paved, the excessive powder is poured into the residual powder recovery box 28 on the right side on the lifting table 29, and the residual powder flows into the powder tank 31 outside the forming chamber 26 through the switch valve 30, and then the powder bearing plate 231 of the powder spreading box is closed. After the powder material is spread, the 3D printer control device directs the laser beam through the laser scanning head 25 to selectively melt the powder material according to the geometric figure scanning data of the current printing material area; since the next printing material region has the same material as the current printing material region 51321, the powder purge recovery operation is not performed. In this way, the printing work of the pure titanium material region 51321 of the molding layer 51 is completed.

In this way, the 3D printing process of the modeling layer 50, 51 is completed.

If the shaping layer 51 is not the last layer, printing of the next layer proceeds, and the printing process of the shaping layer 50 can be referred to for the implementation process. If the shaping layer 51 is the last layer, printing of the multi-material part is completed.

The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.

Claims

1. A multi-material part 3D printer, characterized in that: comprises a forming device, a powder supply device, a residual powder removing device and a control device;

the control device controls the work of the powder supply device, the residual powder removing device and the forming device;

the residual powder removing device further comprises a four-way valve, a multi-way valve and a plurality of electric control valves; the interfaces of the four-way valve are respectively connected with the first dust collection head, the second dust collection head, the third dust collection head and the dust collector through pipelines; the plurality of electric control valves comprise a first electric control valve, a second electric control valve, a third electric control valve, a fourth electric control valve, a fifth electric control valve and a powder cleaning electric control valve of the powder feeding pipe; the first electric control valve is arranged on a pipeline between the first dust collection head and the four-way valve, the second electric control valve is arranged on a pipeline between the second dust collection head and the four-way valve, and the third electric control valve is arranged on a pipeline between the third dust collection head and the four-way valve; the multi-way valve comprises an input interface and at least more than 3 output interfaces; the input interface is connected with the air outlet of the fan through a pipeline; the output interface is connected with the forming chamber through pipelines, and the fourth electric control valve, the fifth electric control valve and the powder cleaning electric control valve of the powder feeding pipe are arranged on the pipelines;

The lower part of the quantitative powder supply funnel is provided with a three-way valve; the first port of the three-way valve is connected with the quantitative powder supply funnel, the second port is connected with the powder feeding pipe through a pipeline, and the third port is connected with the multi-way valve through a pipeline; the number of the powder cleaning electric control valves of the powder feeding pipe is the same as that of the quantitative powder feeding hoppers, and the powder feeding pipes are arranged on pipelines connected with the three-way valve and the multi-way valve;

the powder supply device also comprises a powder spreading box moving mechanism;

2. The multi-material part 3D printer of claim 1, wherein: the powder spreading box comprises a motor and a powder bearing plate of the powder spreading box; the motor is arranged on the side wall of the other side of the powder paving box, which is opposite to the connecting block of the powder paving box; the powder-spreading box powder-bearing plate is arranged in the powder-spreading box and is connected with the motor to realize rotation.

3. The multi-material part 3D printer of claim 2, wherein: the residual powder removing mechanism further comprises an electric control frequency converter; the electric control frequency converter is controlled by a control device; the electric control frequency converter adjusts the running state of the fan according to the frequency parameter transmitted by the control device, and then controllable air flow is formed.

4. A multi-material part 3D printer according to claim 3, characterized in that: the device also comprises a residual powder storage device, wherein the residual powder storage device comprises a residual powder recovery box, a powder tank and a switch valve; the residual powder recovery box is embedded between the forming cylinder body and the side wall of the forming chamber without gaps, and gradually transits from top to bottom from square to conical; the powder tank is connected with the bottom of the residual powder recovery box; the switch valve is arranged between the powder tank and the residual powder recovery box.

5. The 3D printing method for the multi-material part is characterized by comprising the following steps of:

s2: the powder spreading platform descends by a layer thickness distance;

(1) If the powder feeding channels are different, the powder laying box moves for a certain distance, a second dust collection head at one side of the powder laying box is aligned to the powder feeding pipe, a fan is started, air flow is input from a pipeline communicated with the powder feeding pipe, residual powder in the powder feeding channel below the corresponding powder feeding funnel is blown out, the second dust collection head is synchronously operated, the powder adhered in the powder feeding channel and the powder feeding pipe is adsorbed and recovered completely, and the fan is stopped; the powder spreading box moves to the upper part of the forming cylinder body with the powder, and opens the powder bearing plate of the powder spreading box to enable the powder to leak to the lifting platform, the scraping plate then arranges the powder to the lifting platform, meanwhile, the powder spreading box continues to translate to the upper part of the residual powder recovery box, and the residual powder is dumped into the residual powder recovery box; the control device directs the laser beam to selectively melt or sinter the powder material according to the scanning data of the current printing material area through the laser scanning head;

(2) If the powder is the same, the powder spreading box moves to the upper part of the forming cylinder body, the powder bearing plate of the powder spreading box is opened to enable the powder to leak down to the lifting table, the scraping plate is used for arranging the powder on the lifting table, meanwhile, the powder spreading box moves to the upper part of the residual powder recovery box, the residual powder is poured into the residual powder recovery box, and then the powder bearing plate of the powder spreading box is closed; the control device directs the laser beam to selectively melt or sinter the powder material according to the scanning data of the current printing material area through the laser scanning head;

Because the material to be printed next time is the same as this time, the residual powder removing program is not executed, and the printing is finished;

in the residual powder adsorption, recovery and cleaning process, the sucked dust is filtered by a dust collector and a filter, wherein the powder filtered by the dust collector is collected by a dust collection barrel; in the running process of the fan, the electric control frequency converter is controlled by the control device, so that the power frequency of the fan is changed, and the proper air inlet flow is realized;

s5: judging whether the current layer is printed, if not, repeating the steps S3-S5; if the current layer is finished and is not the last layer, repeating the steps S2-S5; if the printing is finished and the current layer is the last layer, the printing of the multi-material part is finished.