CN112140541B - Powder supply and spreading system, forming equipment and powder supply and spreading method - Google Patents

Abstract

The invention relates to a powder supplying and spreading system, a forming device and a powder supplying and spreading method, wherein the powder supplying and spreading system comprises a powder spreading assembly and a powder supplying assembly, wherein: the powder spreading assembly comprises a powder spreading scraper and a linear module for driving the powder spreading scraper to translate along a preset direction; supply the powder assembly including the powder mouth that falls, the powder mouth that falls is located spread the front side of powder scraper direction of advance, and can follow the straight line module removes to in good time with the powder of predetermineeing the volume drop in spread the front side of powder scraper direction of advance, owing to supply the powder assembly to carry out online confession powder along with the shop's powder progress of spreading the powder assembly, cause the disturbance and influence the shaping quality to the object in the shaping when avoiding spreading the powder assembly and promoting big powder heap.

Description

Powder supply and spreading system, forming equipment and powder supply and spreading method

Technical Field

The invention relates to the technical field of 3D printing, in particular to a powder supplying and spreading system, forming equipment and a powder supplying and spreading method.

Background

Powder bed 3D printing technology is one of the important branches of the additive manufacturing field. The working principle of the forming equipment applying the 3D printing technology is as follows: paving fine powder materials on a printing substrate with an opening of a forming cylinder to form a powder thin layer with uniform thickness by using a powder supplying and spreading device, and selectively processing a specific area of the powder thin layer by adopting an energy irradiation or micro-droplet spraying mode to combine the powder thin layer into a sheet-shaped object; and then controlling the printing substrate to descend by a preset height, and executing the powder supplying and spreading action and the forming action of energy irradiation or micro-droplet spraying again until each layer of powder is combined to generate a sheet-shaped object which is vertically accumulated into a three-dimensional formed body. Due to the high-resolution area selection capability of energy irradiation and micro-droplet injection and the micron-sized particle size of the fine powder material, the forming precision and the surface quality of the powder bed 3D printer are both significantly superior to those of melt extrusion forming. Furthermore, considering that the powder and the forming material fill the whole forming cylinder space, the powder bed 3D printing is less dependent on the part support structure than other forming processes. Due to the basic processes of powder paving layer by layer, area selection combination and Z-direction accumulation forming, the powder bed 3D printer can effectively avoid the problem of cutter interference in the traditional numerical control cutting machining, and plays an active role in the forming field of parts with complex geometric characteristics, such as free curved surfaces, cavities, lattices and the like.

The existing powder bed 3D printing and forming equipment is mainly divided into two types according to applicable materials, namely an SLM printer for metal powder forming and an SLS printer for polymer powder forming. In recent years, with the continuous improvement of 3D printing capability of a powder bed, the application of SLM/SLS printers is gradually going to large-scale mass production from a few high-end fields, for example, SLM printers are used for manufacturing integrated oil nozzles, compressor blades with hollow cooling channels, integrated turbine discs and the like in batches; SLS printers are used to manufacture interior/exterior trim panels for automobiles, midsoles for sports shoes, and the like. Batch manufacturing applications also pull SLM/SLS equipment back towards higher processing performance. In order to increase the speed, the laser scanning device of the SLM/SLS printer is increased from several meters per second to twenty more than one meter per second; in order to enlarge the powder spreading breadth, the laser scanning device and the micro-spray head of the SLM/SLS printer are developed into an array combination from a single laser.

However, in the SLM/SLS printer, besides the scanning speed/jetting speed of the laser scanning device and the micro-nozzle, the spreading effect of the thin powder layer greatly restricts the expansion of the printing breadth and the further improvement of the comprehensive performance of the powder bed 3D printer. Specifically, as the breading web increases, the volume of the pile needs to be increased to meet the breading requirements. However, before each powder spreading, the powder pile needs to be replenished once before the powder spreading device, and the powder pile is pushed to advance by the powder spreading device so as to uniformly spread the powder pile on the printing substrate in the advancing process. Along with the increase of the forming size, the initial powder pile required to be supplemented before powder paving at each time is also larger and larger, the driving force for pushing the powder pile to advance by the powder paving device is also increased, and the powder pile is easy to interfere to enable objects in forming to incline or shake, so that the forming quality is influenced.

Disclosure of Invention

In view of the above, it is necessary to provide a powder supplying and spreading system, a molding apparatus and a powder supplying and spreading method, in which a powder supplying assembly in the powder supplying and spreading system supplies powder on line along with the powder spreading progress of a powder spreading assembly, so as to avoid the influence on molding quality due to disturbance on an object in molding when the powder spreading assembly pushes a large powder pile.

The embodiment of the invention firstly provides a powder supply and powder laying system, which comprises a powder laying assembly and a powder supply assembly, wherein:

the powder spreading assembly comprises a powder spreading scraper and a linear module for driving the powder spreading scraper to translate along a preset direction;

the powder supply assembly comprises a powder falling port, the powder falling port is located on the front side of the advancing direction of the powder paving scraper, and can move along with the linear module, so that powder with preset quantity can be timely fallen on the front side of the advancing direction of the powder paving scraper.

In one embodiment, the powder falling ports are multiple and arranged side by side along the direction perpendicular to the moving direction of the powder spreading scraper; the powder supply assembly further comprises a constant volume feeding device, and the constant volume feeding device comprises: a powder supply container having a plurality of powder tanks having the same volume for containing powder; the powder supply scraper moves relative to the powder supply container to scrape off powder exceeding the upper end of the powder groove; and the plurality of feeding pipes are correspondingly arranged in each powder groove and are positioned at the rear side of the powder supply scraper plate so as to output the powder with the fixed volume in the powder groove to the corresponding powder falling port.

In one embodiment, the powder supply assembly further comprises a rotary table for driving the powder supply container to rotate around a fixed shaft, the powder groove is annularly arranged around the fixed shaft, and the powder supply scraper can scrape powder exceeding the upper end of the powder groove along with the rotation of the powder supply container.

In one embodiment, the powder supply assembly further comprises a bin for outputting powder into the powder supply container, and a blanking opening of the bin is located on the front side of the powder supply scraper.

In one embodiment, the powder supply assembly further comprises a plurality of negative pressure pipes and powder falling pipes, the number of the negative pressure pipes corresponds to that of the feeding pipes, one end of each negative pressure pipe is communicated with the feeding pipe, and the other end of each negative pressure pipe is communicated with the vacuum generator, so that the vacuum generator can generate a preset value of negative pressure in the feeding pipe through the negative pressure pipes; one end of the powder falling pipe is communicated to the feeding pipe, and the pipe orifice of the other end is arranged to be the powder falling port.

In one embodiment, the powder supply assembly further comprises a first control valve and a second control valve, the number of the first control valves corresponds to that of the feeding pipes, and the first control valve is arranged at the powder dropping pipe and used for controlling the opening and closing of the powder dropping port; the second control valve is arranged at the negative pressure pipe and is used for controlling the connection/disconnection between the vacuum generator and the negative pressure pipe.

In one embodiment, the powder supply and spreading system further comprises a control device, and the powder supply assembly is provided with a feeding station and a blanking station under the control of the control device;

at the feeding station, the control device controls the first control valve to be closed and the second control valve to be opened, so that the feeding pipe can extract powder with a constant volume from the powder groove to the powder dropping pipe under the action of negative pressure;

at the blanking station, the control device controls the first control valve to be opened and the second control valve to be closed, so that the negative pressure pipe and the vacuum generator are stopped, and the powder in the powder falling pipe can be released to the front side of the advancing direction of the powder spreading scraper from the powder falling port.

The second aspect of the embodiment of the present invention further provides a molding apparatus, which includes the above powder supplying and spreading system.

The third aspect of the embodiments of the present invention also provides a powder laying method, including the steps of:

powder supply step: outputting a preset amount of powder to the front side of the advancing direction of the powder spreading scraper at preset time intervals;

powder spreading: and driving the powder spreading scraper to move horizontally along the preset direction, and scraping the powder output for multiple times in the powder supply step.

In one embodiment, after the powder paving step is performed for a preset number of times, a selective area scanning/spraying step is performed to form a sheet structure area;

after the sheet-shaped structure area is formed for the first time, the blanking speed of each line or each plurality of lines in the moving direction of the powder spreading scraper is adjusted according to the sheet-shaped structure area, so that the blanking speed in the sheet-shaped structure area is larger than that outside the sheet-shaped structure area.

In the powder supply and spreading system, the forming equipment and the powder supply and spreading method, the powder falling port moves along with the powder spreading scraper and supplies powder to the front side of the powder spreading scraper when needed, so that the powder bed is formed, the large powder pile is prevented from being formed at one time, the moving process of the powder spreading scraper does not need large driving force, and the disturbance of parts in forming is also avoided.

Drawings

FIG. 1 is a schematic structural view of a molding apparatus according to an embodiment;

FIG. 2 is a partial structural view of the molding apparatus shown in FIG. 1, showing the relative position of the powder spreading assembly and the print substrate;

FIG. 3 is a schematic structural view of a siphon tube set formed by the feed tube, the powder dropping tube and the negative pressure tube;

fig. 4 is a schematic structural view of a powder supply container in the molding apparatus shown in fig. 1.

In the figure: 100. a powder laying assembly; 11. spreading a powder scraper; 12. a linear module; 13. mounting a plate; 200. a powder supply assembly; 21. a constant volume feeding device; 211. a powder supply container; 2111. a powder groove; 212. a powder supply scraper plate; 213. A feed pipe; 2131. a feed inlet; 2132. a suction section; 2133. self-landing; 22. a turntable; 23. a storage bin; 24. a negative pressure tube; 25. a powder dropping pipe; 251. powder falling port; 26. a first control valve; 27. a second control valve; 300. a vacuum generator; 400. printing a substrate; 500. a lamellar structure region; 600. and a frame.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like are used in the indicated orientations and positional relationships based on the drawings for convenience in describing and simplifying the description, but do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

In the present invention, unless otherwise specifically stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication connection; either directly or indirectly through intervening media, either internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art. The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

In a powder bed 3D printing apparatus, the sequence of actions of the apparatus is: supplying powder to form a powder pile; then pushing the powder pile to spread on the printing substrate to form a powder bed, and carrying the residual powder into a residual powder box by a powder spreading device; then, carrying out selective laser scanning or adhesive spraying on the powder bed to form a layer of sheet structure; the forming cylinder acts to enable the printing substrate to descend by the thickness of a powder bed, and then the processes from powder pile forming to scanning/spraying forming of the sheet structure are repeated on the formed sheet structure until the printing substrate is accumulated to form a complete three-dimensional forming body.

In the process, in order to ensure the printing quality and avoid the influence of the collapse of the edge of the part on the forming effect, the size of the powder bed is generally selected based on the slice area of the three-dimensional forming body to be printed, the upper surface of the printing substrate is required to be fully paved with powder to meet the size requirement of the powder bed when the powder is paved, and then the powder bed on the printing substrate is subjected to selective scanning. The required powder bulk increases with the increase in the size of the powder bed and the increase in the size of the three-dimensional shaped body. And before the printing substrate is scanned/sprayed for the first time to form the sheet structure, one layer or a plurality of layers of powder are already paved, so that when the powder is paved again after the sheet structure is formed for the first time, the size of the powder pile is larger, the driving force required for pushing the powder pile is also larger, and the formed sheet structure is easy to incline, disturb and the like in the powder pile during powder paving.

Furthermore, the printing substrate is of a regular quadrilateral structure, the slicing structure of the three-dimensional forming body often has an irregular outline, and when powder is spread, powder piles are uniformly and linearly distributed along one side edge of the printing substrate; the flaky structure area formed after scanning or spraying is often lower than other positions in surface, the powder amount consumption at the position is large, the powder amount consumption at other positions is small, and in order to meet the powder paving requirement, the powder pile volume needs to be selected according to the position with the maximum powder consumption, so that the traditional powder paving mode is large in residual powder amount, and the one-time utilization rate of powder is low.

In view of the above problems, some skilled in the art propose solutions to reduce the amount of residual powder as much as possible by changing the width of the powder pile and changing the slicing manner, and further propose improved solutions to directly provide more efficient treatment of residual powder. However, to meet the printing requirement, a powder bed with a thickness meeting the requirement is necessarily formed, and excessive reduction of the breadth size of the powder bed can cause the edge of the formed sheet structure to be too close to the edge of the powder bed, so that the collapse of powder at the edge and the like can obviously affect the printing quality, therefore, the problem of residual powder of the powder bed 3D printing equipment is difficult to improve in a powder laying mode to a great extent, and even if the problem is improved, disturbance to the formed sheet structure when a large-volume powder pile is pushed cannot be avoided.

In view of the above, the embodiment of the present invention first provides a powder supplying and spreading system, which can be applied to the molding apparatus shown in fig. 1. Referring to fig. 1 and 2, the powder supplying and spreading system includes a powder spreading assembly 100 and a powder supplying assembly 200, wherein:

the powder spreading assembly 100 includes a powder spreading scraper 11 and a linear module 12 for driving the powder spreading scraper 11 to move horizontally along a preset direction. Referring to the marks in fig. 1 and fig. 2, the linear module 12 drives the powder spreading blade 11 to translate along the direction indicated by the arrow in the figure, so that the powder spreading blade 11 scrapes the upper surface of the printing substrate 400 of the forming device, thereby forming a powder bed on the upper surface of the printing substrate 400. The linear module 12 can adopt any driving mechanism capable of realizing linear motion, such as a screw nut transmission mechanism, an electric cylinder, a linear guide rail slide block and the like, and in order to enable the motion of the powder spreading scraper 11 to be more stable and accurate, the linear module 12 can also have structures for guiding the motion of the powder spreading scraper 11.

Part of the structure of the powder supply assembly 200 is mounted on the linear module 12 and can move along with the linear module, so that the powder falling port 251 (marked in fig. 3) in the powder supply assembly 200 is always kept at the front side of the advancing direction of the powder spreading scraper 11, thus, the powder falling port 251 outputs certain powder at a preset time point, the powder directly falls at the front side of the advancing direction of the powder spreading scraper 11, and the linear module 12 drives the powder spreading scraper 11 to move further to scrape the powder to form a powder bed.

So configured, the powder supply assembly 200 no longer forms a powder pile prior to powder placement as in conventional powder supply devices. But moves along with the powder spreading scraper 11 and supplies powder outwards when needed, so that a large powder pile is prevented from being formed at one time while the powder supply required for forming a powder bed is met, a large driving force is not required in the moving process of the powder spreading scraper 11, and the disturbance of parts in the forming process is also avoided. Before the powder spreading scraper 11 starts spreading powder to approach the contour of the formed laminated structure, the powder supply assembly 200 can output powder outwards at a lower frequency due to a smaller required amount of powder, so as to reduce the amount of residual powder, and in the following powder spreading process, the powder output frequency of the powder falling port 251 can be adjusted at any time based on the amount of powder on the front side in the moving direction of the powder spreading scraper 11, so that the amount of residual powder finally pushed into the residual powder box is further reduced.

As shown in fig. 3 and 4 in conjunction with fig. 1, the powder supply assembly 200 may include a constant volume feeder 21, and the constant volume feeder 21 may output a predetermined volume of powder outwards at a time, so as to facilitate the flexible adjustment of the powder supply amount and the formation of a uniform small powder pile during powder supply.

In one embodiment, the constant volume feeder 21 includes a powder supply container 211, a powder supply scraper 212, and a plurality of feed tubes 213. Each feeding pipe 213 is connected to a negative pressure pipe 24 and a powder dropping pipe 25, which together form a siphon set shown in fig. 3.

Referring to fig. 1 and 4, the powder supply container 211 has a plurality of powder grooves 2111 for containing powder, the internal volume of each powder groove 2111 is the same, and the number of powder grooves 2111 is set corresponding to the number of feed tubes 213 to supply the same volume of powder to each feed tube 213, respectively.

The powder supply scraper 212 and the powder supply container 211 may move relatively, the powder supply scraper 212 may move relative to the powder supply container 211, the powder supply container 211 may move while the powder supply scraper 212 is stationary, or both may move relatively. The powder supply scraper 212 serves to scrape off the upper surfaces of the powder grooves 2111 so that the powder just fills each powder groove 2111, thereby determining the volume of the powder by the powder grooves 2111.

In the illustrated embodiment, the powder supply container 211 has a cylindrical structure, and the plurality of powder grooves 2111 are provided as concentric annular grooves. The powder supply assembly 200 further includes a turntable 22 for driving the powder supply container 211 to rotate, the powder supply scraper 212 is fixed on the frame 600 in the molding apparatus, and the powder supply container 211 rotates along with the turntable 22, so that the powder supply scraper 212 and the powder supply container 211 move relatively to each other to scrape off the powder in the powder groove 2111.

In other embodiments, the powder supply container 211 may have a rectangular box structure, the box and the powder supply scraper 212 move relatively in a linear direction, the powder grooves 2111 extend in the moving direction of the box, and the plurality of powder grooves 2111 are arranged side by side in the moving direction perpendicular to the box, which can achieve the same function.

Referring to fig. 1 and 4, the lower end edge of the powder supply scraper 212 is flush with the upper end of the groove side wall of the powder groove 2111, so that powder just fills each powder groove of equal volume, and the amount of powder in the powder groove 2111 on the rear side (with respect to the direction of its scraping movement) of the powder supply scraper 212 is fixed.

Referring back to fig. 1, the powder supply assembly 200 may further include a bin 23 fixedly mounted on the frame 600 for outputting powder into the powder supply container 211 to fill the powder slot 2111. The blanking port of the hopper 23 is located at the front side of the powder supply scraper 212 so that the powder supply scraper 212 can scrape the powder flat in the powder groove 2111 as it rotates further relative to the powder supply container 211.

In order to output the powder in the powder groove 2111 to the front side of the movement direction of the powder laying blade 11, the feed pipe 213, the negative pressure pipe 24 and the powder dropping pipe 25 are communicated in a predetermined manner to form a siphon group as shown in fig. 1 and 3. Wherein: one end of the negative pressure pipe 24 communicates with a vacuum generator 300 in the molding apparatus, so that the vacuum generator 300 can generate a negative pressure of a preset value on the feed pipe 213 by the communicating action of the negative pressure pipe 24. The feed pipe 213 has a feed port 2131, and the feed port 2131 is provided corresponding to the powder slot 2111 to draw out the powder in the powder slot 2111 by negative pressure. One end of the powder dropping pipe 25 is communicated to the feeding pipe 213, and the other end is provided with the aforementioned powder dropping port 251 for outputting the powder to the front side of the powder laying blade 11.

With continued reference to FIG. 3, the feed tube 213 can be generally divided into a suction section 2132 adjacent the feed port 2131 and a self-landing section 2133 adjacent the powder drop tube 25. As can be seen from the foregoing description, in one embodiment of the present invention, the powder tank 2111 is used as a structure for constant volume. This is because, when powder is extracted by negative pressure, the gas flow fluctuates greatly due to a large compression ratio of the gas, and the output of the powder is unstable by the gas flow alone as the power for powder conveyance, which affects the molding quality. In the embodiment of the present invention, since the powder groove 2111 has a constant volume and is filled with powder, the powder in the powder groove 2111 can be completely pumped out to the powder dropping pipe 25 and output as long as the vacuum generator 300 generates a sufficiently large negative pressure at the feeding pipe 213 through the negative pressure pipe 24 (the negative pressure value may be slightly larger than the actual requirement for satisfying the requirement).

In the illustrated embodiment, the powder supply assembly 200 further includes a first control valve 26 disposed at a corresponding position on each powder dropping pipe 25, and a second control valve 27 correspondingly disposed between each negative pressure pipe 24 and the vacuum generator 300. The siphon group composed of three tubes realizes the quantitative extraction and output of the powder in the following pulse action mode:

under the control of the first control valve 26, the powder dropping port 251 of the powder dropping pipe 25 is closed, at this time, the second control valve 27 is opened to generate a preset negative pressure at the feed port 2131, and the powder is sucked to the top point of the suction section 2132, and then the powder can fall into the powder dropping pipe 25 under the action of the self weight, so that the actions are intermittently performed fully, a preset amount of powder is filled into the powder dropping pipe 25, and then the first control valve 26 is opened to enable the preset amount of powder to be output to the front side of the powder spreading scraper 11 through the powder dropping port 251.

The powder supply and powder spreading system further comprises a control device for controlling the powder supply assembly 200 to be switched between the feeding station and the blanking station, wherein:

at the feeding station, the control device controls the first control valve 26 to be closed and the second control valve 27 to be opened, so that the feeding pipe 213 can extract powder with a constant volume from the powder groove 2111 into the powder dropping pipe 25 under the action of negative pressure;

in the blanking station, the control device controls the first control valve 26 to open and the second control valve 27 to close, so that the negative pressure pipe 24 is disconnected from the vacuum generator 300, and the powder in the powder dropping pipe 25 can be released from the powder dropping port 251.

In order to enable the powder dropping port 251 of the powder supply assembly 200 to move along with the linear module 12 and output the powder to the front side of the powder spreading scraper 11 at a proper time, referring to fig. 2, the powder spreading assembly 100 may further include a mounting plate 13 for mounting a corresponding structure at the center of the powder supply assembly 200, and the mounting plate 13 may be provided with a through hole for allowing one end of the powder dropping pipe 25 having the powder dropping port 251 to pass through. In other embodiments, the powder outlet 251 of the powder supply assembly 200 may move along with the linear module 12 by other structures. Correspondingly, the three tubes of the siphon group shown in fig. 3 are also engraved as one profiled tube body communicating in the aforementioned defined manner, and some of the tube bodies of the group may be configured as flexible tubes so as to be elastically deformed in accordance with the movement of the linear module 12.

A second aspect of the invention further provides a molding apparatus comprising a powder supply and spreading system according to any of the embodiments described above.

The third aspect of the present invention also provides a powder spreading method, including the steps of:

powder supply step: outputting a preset amount of powder to the front side of the advancing direction of the powder spreading scraper at preset time intervals;

powder spreading: and driving the powder spreading scraper to move horizontally along the preset direction, and scraping the powder output for multiple times in the powder supply step.

The powder supplying step is carried out intermittently along with the execution of the powder paving step, so that the powder supplying step is carried out at least twice in the process of forming a layer of powder bed, the formation of large-volume powder piles is avoided, the powder paving scraper can be pushed to act without large driving force in the powder paving step, and the disturbance to the formed sheet structure is reduced.

Further, after the powder laying step is performed a preset number of times, a selective area scanning/spraying step is performed to form a sheet-like structure area 500;

after the sheet-shaped structure area 500 is formed for the first time, the blanking rate of each line or each plurality of lines in the moving direction of the powder spreading scraper is adjusted according to the contour position of the sheet-shaped structure area 500, so that the blanking rate in the sheet-shaped structure area 500 is larger than that outside the sheet-shaped structure area.

After the selective scanning/spraying step is performed, part of the powder bed forms the sheet-shaped structure area 500, the surface height of the sheet-shaped structure area 500 is lower than other positions of the powder bed due to the solidification and shrinkage effects of the powder, when the powder is spread again, the required powder amount on the upper surface of the sheet-shaped structure area 500 is larger, the required powder amount on other positions is relatively larger, and the powder supply and blanking rate of a single line or a plurality of lines is adjusted according to the required powder amount, so that the residual powder amount can be further reduced.

It can be understood that, along the direction in which the plurality of powder falling ports 251 are arranged side by side, the larger the number of the powder falling ports 251 is within a predetermined length, the more the powder pile is formed, and the powder formed is distributed in a row when each powder falling port 251 is synchronously supplied with powder on line as the linear die set 12 moves. When the powder feeding and blanking rate is adjusted, the single adjustment is likely to have a large control amount, and at the moment, the powder falling ports 251 with large influence can be roughly adjusted, so that the purpose of adjusting the powder feeding rate according to lines is achieved.

For example, after the first formation of the sheet-like structure region 500, the following steps may be performed:

s01: the linear module 12 drives the powder spreading scraper 11 and the powder falling port 251 to move rightwards from the left initial position until the powder falling port 251 approaches the edge of the powder bed, and each powder falling port 251 does not output powder in the period;

s02: the linear module 12 drives the powder spreading scraper 11 and the powder falling ports 251 to move rightwards continuously until one powder falling port 251 approaches the sheet-shaped structure area 500, and each powder falling port 251 supplies powder at a low speed;

s03: the linear module 12 drives the powder spreading scraper 11 and the powder falling port 251 to move rightwards continuously until the powder falling port 251 passes through the sheet-shaped structure area 500, the powder falling port 251 correspondingly falling in the sheet-shaped structure area 500 supplies powder at a high rate so as to match the powder demand of the sheet-shaped structure area 500, and the powder falling port 251 located outside the sheet-shaped structure area 500 continues to supply powder at a low rate;

s04: the linear module 12 drives the powder spreading scraper 11 and the powder falling port 251 to move rightwards continuously until the powder falling port 251 moves beyond the range of the sheet-shaped structure area 500, and all the powder falling ports 251 are changed into low-speed powder supply again;

s05: the linear module 12 drives the powder spreading scraper 11 and the powder dropping port 251 to return to the initial position leftwards, and the powder supplying and spreading process is finished.

It is understood that when the contour of the sheet structure area 500 changes, steps S02-S05 can be adjusted accordingly, as long as it is ensured that: when the powder falling port 251 approaches the sheet structure area 500, the corresponding powder falling port 251 outputs powder at a high rate, and when the powder falling port 251 moves in other areas, the powder falling port 251 supplies powder at a low rate. In the description of the steps, the powder feeding rate of the powder dropping port 251 is referred to, and actually, the powder feeding rate of the powder dropping port 251 corresponds to the overall powder feeding rate of the powder feeding assembly 200, and the powder output rate of the powder dropping port 251 is only a visual expression form thereof.

All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (8)

1. A powder supply and powder placement system, comprising a powder placement assembly (100) and a powder supply assembly (200), wherein:

the powder paving assembly (100) comprises a powder paving scraper (11) and a linear module (12) for driving the powder paving scraper (11) to move horizontally along a preset direction;

the powder supply assembly (200) comprises a powder falling port (251), and the powder falling port (251) is positioned on the front side of the advancing direction of the powder paving scraper (11) and can move along with the linear module (12) so as to timely fall a preset amount of powder on the front side of the advancing direction of the powder paving scraper (11);

the powder falling ports (251) are arranged in parallel along the direction vertical to the moving direction of the powder spreading scraper (11);

the powder supply assembly (200) further comprises a plurality of feeding pipes (213), negative pressure pipes (24), powder falling pipes (25), first control valves (26) and second control valves (27), the number of the feeding pipes corresponds to that of the powder falling ports (251), the powder supply assembly (200) is provided with a powder groove (2111), one end of each negative pressure pipe (24) is communicated to the corresponding feeding pipe (213), and the other end of each negative pressure pipe is communicated to the corresponding vacuum generator (300);

the powder supply and spreading system further comprises a control device, and the powder supply assembly (200) is provided with a feeding station and a blanking station under the control of the control device;

at the feeding station, the control device controls the first control valve (26) to be closed and the second control valve (27) to be opened so that the feeding pipe (213) can draw powder with a constant volume from the powder groove (2111) to the powder dropping pipe (25) under the action of negative pressure;

at the blanking station, the control device controls the first control valve (26) to be opened and the second control valve (27) to be closed, so that the negative pressure pipe (24) is cut off from the vacuum generator (300), and the powder in the powder dropping pipe (25) can be released from the powder dropping port (251) to the front side of the advancing direction of the powder paving scraper (11);

after the sheet structure area (500) is formed for the first time, the powder spreading action of the next step is carried out according to the following steps:

the straight line module (12) drives the powder spreading scraper (11) and the powder falling port (251) to move rightwards from the left initial position until the powder falling port (251) approaches the edge of the powder bed, and each powder falling port (251) does not output powder in the period;

the straight line module (12) drives the powder spreading scraper (11) and the powder falling ports (251) to move rightwards continuously until one of the powder falling ports (251) approaches the sheet-shaped structure area (500), and each powder falling port (251) adopts low-speed powder supply;

the straight line module (12) drives the powder spreading scraper (11) and the powder falling port (251) to move rightwards continuously until the powder falling port (251) starts to pass through the sheet-shaped structure area (500), powder is supplied at a high speed corresponding to the powder falling port (251) falling in the sheet-shaped structure area (500) so as to match the powder demand of the sheet-shaped structure area (500), and the powder falling port (251) located outside the sheet-shaped structure area (500) continues to maintain low-speed powder supply;

the straight line module (12) drives the powder spreading scraper (11) and the powder falling port (251) to move rightwards continuously until the powder falling port (251) moves out of the range of the sheet structure area (500), and all the powder falling ports (251) are changed into low-speed powder supply again;

the linear module (12) drives the powder spreading scraper (11) and the powder falling port (251) to return to the initial position leftwards, and the powder supplying and spreading process is finished.

2. A powder supply and powder laying system according to claim 1, wherein the powder supply assembly (200) further comprises a constant volume feeding device (21), the constant volume feeding device (21) comprising:

a powder supply container (211) having a plurality of powder tanks (2111) having the same volume for containing powder;

a powder supply scraper (212) which moves relative to the powder supply container (211) to scrape off powder beyond the upper end of the powder groove (2111);

the feeding pipes (213) are correspondingly arranged in each powder groove (2111) and are positioned at the rear side of the powder supply scraper plate (212) so as to output the powder with the volume determined in the powder groove (2111) to the corresponding powder falling port (251).

3. The powder supply and spreading system according to claim 2, wherein the powder supply assembly (200) further comprises a turntable (22) for driving the powder supply container (211) to rotate around a fixed axis, the powder groove (2111) is arranged in a ring shape around the fixed axis, and the powder supply scraper (212) can scrape off powder exceeding the upper end of the powder groove (2111) along with the rotation of the powder supply container (211).

4. A powder supplying and spreading system according to claim 2, wherein the powder supplying assembly (200) further comprises a bin (23) for outputting powder into the powder supplying container (211), and a discharge port of the bin (23) is located at a front side of the powder supplying scraper (212).

5. The powder supply and spreading system according to claim 2, wherein the negative pressure pipe (24) is connected to the feeding pipe (213) at one end and to the vacuum generator (300) at the other end, so that the vacuum generator (300) can generate a preset value of negative pressure in the feeding pipe (213) through the negative pressure pipe (24); one end of the powder falling pipe (25) is communicated to the feeding pipe (213), and the pipe orifice of the other end is set as the powder falling port (251).

6. The powder supplying and spreading system according to claim 5, wherein the first control valve (26) is installed at the powder dropping pipe (25) and is used for controlling the opening and closing of the powder dropping port (251); the second control valve (27) is installed at the negative pressure pipe (24) and is used for controlling the connection/disconnection between the vacuum generator (300) and the negative pressure pipe (24).

7. A molding apparatus comprising the powder supply and powder laying system according to any one of claims 1 to 6.

8. A powder supplying and laying method for the powder supplying and laying system according to any one of claims 1 to 6, comprising the steps of:

powder supply step: outputting a preset amount of powder to the front side of the advancing direction of the powder spreading scraper at preset time intervals;

powder paving: driving the powder paving scraper to move horizontally along a preset direction, and scraping the powder output for multiple times in the powder supply step;

after the powder paving step is carried out for a preset time, a selective area scanning/spraying step is carried out to form a sheet-shaped structure area;

after the sheet-shaped structure area is formed for the first time, the blanking speed of each line or each plurality of lines in the moving direction of the powder spreading scraper is adjusted according to the sheet-shaped structure area, so that the blanking speed in the sheet-shaped structure area is larger than that outside the sheet-shaped structure area.

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