WO2021017129A1

WO2021017129A1 - Additive fabrication device and forming method

Info

Publication number: WO2021017129A1
Application number: PCT/CN2019/107621
Authority: WO
Inventors: 陈祯; 韦继翀; 张树哲; 卢秉恒; 邹亚桐; 刘亮; 魏培; 雷云佩
Original assignee: 西安增材制造国家研究院有限公司; 西安交通大学
Priority date: 2019-07-31
Filing date: 2019-09-25
Publication date: 2021-02-04
Also published as: CN110315079B; CN110315079A

Abstract

An additive fabrication device, comprising a rotary worktable (1), a lifting platform (2), a forming assembly (3), a laser printing device (4) and a material feeding and paving assembly (5); the rotary worktable is formed by means of a fixed base (6) and a rotary plate (7), and cooperates with the lifting platform to form a space rotary forming device, and a telescopic protective cover (9) is provided between the fixed base and the lifting platform, so that a working sealed cavity is formed between the telescopic protective cover, the fixed base and the lifting platform. In addition, there is a powder paving and forming method performed on the basis of the described additive fabrication device. The additive fabrication device uses a dynamic powder cylinder model in the forming process, and may enable a forming cylinder and a workpiece to be conformally arranged, thereby reducing the gap between the workpiece and the forming cylinder body. The additive fabrication device cuts down on raw materials used for additive formation, so excess powder does not need to be recovered in a powder paving process, thus increasing the utilization efficiency of the raw materials. By using the dynamic powder cylinder model, an area that does not need to be formed may be isolated, thus increasing the forming efficiency. The telescopic protective cover is used to seal a forming space, so that an atmosphere protection environment is provided, and the sealing means is simple and reliable.

Description

Additive manufacturing device and forming method

Technical field

The invention belongs to the technical field of additive manufacturing, and relates to an additive manufacturing device and a forming method.

Background technique

Selective Laser Melting (SLM) forming technology in metal additive manufacturing technology. Because powder can play a self-supporting role, it has the advantages of high forming accuracy and stronger structure of complex structures. It is used in aerospace, automotive, high-end High-end fields such as molds and medical treatment have broad application prospects. At present, SLM forming technology has a small size (generally less than 500mm). Manufacturing large-size metal components is a technical bottleneck that SLM technology is difficult to break through for a long time. This technical bottleneck is determined by the technological characteristics of the SLM forming technology itself: the forming of the workpiece requires powder to be spread layer by layer in the forming cylinder, and then a laser is used to scan a specific area layer by layer to melt the powder. The larger the size of the formed workpiece, the larger the required forming cylinder, the longer the waiting time for powder spreading, and the lower the powder utilization rate. Therefore, the forming efficiency is reduced and the production cost is greatly increased. At present, most SLM forming equipment suppliers at home and abroad use multi-beam splicing to improve forming efficiency, but there is currently no effective method to improve powder utilization and shorten the waiting time for powder spreading.

Summary of the invention

The purpose of the present invention is to provide an additive manufacturing device and forming method to overcome the shortcomings of the prior art.

To achieve the above objective, the present invention adopts the following technical solutions:

An additive manufacturing device, including a rotating worktable, a lifting platform, a forming component, a laser printing device, and a feeding and leveling component;

The forming components, laser printing device and feeding and leveling components are all installed on the lifting platform through the XY rail system, and the lifting platform is driven to move along the Z axis through the Z rail system;

The rotating workbench includes a fixed base and a turntable. A substrate is fixed on the turntable, and the turntable can rotate relative to the fixed base;

A retractable protective cover is arranged between the fixed base and the lifting platform. The upper and lower ends of the retractable protective cover are sealed and fixedly connected with the lifting platform and the fixed base respectively. The working sealed cavity is formed between the retractable protective cover, the fixed base and the lifting platform, and is formed The print head of the assembly, the print head of the laser printing device and the scraper part of the feeding and leveling assembly are all located in the working sealed cavity.

Further, a drive motor is provided at the lower end of the fixed base, the drive motor is connected to the turntable through a drive shaft, the drive shaft penetrates the fixed base, and the drive shaft and the fixed base are sealed.

Further, the Z-direction guide rail system includes columns arranged on both sides of the lifting platform, a vertical rail is provided on the side of the column close to the lifting platform, a motor is provided at the upper end of the column, and a lead screw arranged along the vertical rail is fixed at the output end of the motor , The side of the lifting platform is fixed with a nut for driving with the lead screw.

Further, the nut is fixed on the side of the lifting platform through the nut seat.

Further, the forming component selects one of a fused deposition forming printing system, a laser near net forming printing system or a cold metal transfer welding system.

Further, an X-direction horizontal guide rail system is provided at the bottom of the rotating worktable, and the X-direction horizontal guide rail system adopts a screw guide rail platform.

Furthermore, the lead screw guide rail platform includes a support platform and a guide rail arranged on the support platform. The lower end of the rotating worktable is provided with a sliding block that cooperates with the guide rail. The lead screw guide rail platform is provided with a transmission motor, and the output end of the transmission motor is connected for transmission. Screw, the bottom of the rotating worktable is provided with a transmission nut which is matched with the transmission screw.

Further, the upright post is fixed on the lead screw guide rail platform; the upper ends of the two upright posts are provided with cross beams.

Further, the XY-way rail system adopts a horizontal rail system.

Furthermore, a precision grating ruler is installed on the XY-direction rail system, the X-direction horizontal rail system and the Z-direction rail system.

A forming method based on an additive manufacturing device includes the following steps:

Step 1). First prepare the dynamic powder cylinder model of the part to be formed: remember that the two side walls of the internal cavity of the dynamic powder cylinder model are the first side wall and the second side wall, respectively. Finally closed in the horizontal direction to form the cross-sectional profile of the dynamic powder cylinder. The first and second side walls of the dynamic powder cylinder model and the base plate as the bottom surface constitute the forming area of the part to be formed; on the same horizontal section, the dynamic powder cylinder model The cavity forms a cavity pattern, the part to be formed forms a part pattern, and the cavity pattern and the part pattern are similar patterns;

Determine the cross-sectional shape and size of the dynamic powder cylinder model according to the shape characteristics of the part to be formed, and then use the additive forming method to prepare the dynamic powder cylinder model; during the forming process of the dynamic powder cylinder model, at any forming height, the dynamic powder cylinder model will The parts to be formed are wrapped in the dynamic powder cylinder model, and the dynamic powder cylinder model is formed to the initial height;

Step 2), and then rotate and spread powder in the dynamic powder tank model of the formed part, and perform SLM forming processing on the completed powder spread part. During the forming process, the powder surface of the formed part is always lower than the dynamic powder from the initial height. The molding surface of the cylinder model is 5-50mm.

Further, during the forming process, an inert gas is introduced into the retractable protective cover to form an inert atmosphere; the dynamic powder tank model of the layer is divided and set along its cross-sectional contour trajectory into several successive regions for local powder spreading and SLM Shaped.

Further, a scraper is used to spread powder in the dynamic powder tank model while the rotating table rotates, the powder spreading device spreading thickness is the primary forming thickness; the powder spreading device makes a spiral upward movement relative to the part to be formed in the dynamic powder tank model; the scraper While spreading powder, the worktable rotates, and the lifting platform synchronously raises it. Each time the rotating worktable rotates, the lifting platform will raise a height of the powder spreading layer, and the entire space trajectory of the scraper spreading powder is a spiral relative to the part to be formed. Curve; while the scraper spreads powder along the spiral track, the laser printing device sinters the powder spread area.

Compared with the prior art, the present invention has the following beneficial technical effects:

The invention provides an additive manufacturing device and a forming method. The rotating worktable, the lifting platform, the forming assembly, the laser printing device and the feeding and paving assembly are set; the forming assembly, the laser printing device and the feeding and paving assembly are passed through an XY rail system Installed on the lifting platform to form an X/Y/Z space forming device. A rotating worktable is formed by a fixed base and a turntable, and a space rotating forming device is formed by cooperating with the lifting platform. A retractable protective cover is set between the fixed base and the lifting platform. The upper and lower ends of the retractable protective cover are respectively sealed and fixedly connected with the lifting platform and the fixed base, so that a working sealed cavity is formed between the retractable protective cover, the fixed base and the lifting platform, thereby facilitating SLM forming in the working sealed cavity. The device has a simple structure , There is no need to use a fixed shape, fixed size forming cylinder, which can greatly reduce the equipment cost. At the same time, because there is no fixed forming cylinder, there is no need to consider the sealing problem between the forming platform and the forming cylinder, which simplifies the structure of the equipment . The use of a dynamic powder cylinder model in the forming process can make the forming cylinder and the workpiece conform to the shape, reduce the gap between the workpiece and the forming cylinder, greatly save the raw materials used for additive forming, and improve the efficiency of raw materials. Using the dynamic powder tank model, there is no need to recover excess powder in the powder spreading process, which further improves the use efficiency of raw materials. Using the dynamic powder tank model can isolate areas that do not need to be formed, reduce the spread of powder, and improve the forming efficiency. Use the retractable protective cover to close the forming space, provide an atmosphere protection environment, and the sealing method is simple and reliable. In addition, the volume of this enclosed space is the smallest in the initial stage of forming the workpiece. In this way, the efficiency of "washing" can be improved and the preparation time before the forming of the workpiece can be shortened.

Further, the spiral trajectory forming method can be used for powder spreading while scanning and sintering forming, eliminating the waiting time for powder spreading. The laser scanning sintering forming action and the powder spreading action can be performed simultaneously and continuously until the entire workpiece is formed. Greatly improve the forming efficiency.

Furthermore, the Z-direction guide rail system adopts lead screw transmission, which has stable transmission and high precision.

Description of the drawings

Figure 1 is a schematic diagram of the structure of the present invention.

Figure 2 is a schematic diagram of a cross-sectional view of the dynamic powder cylinder model and the formed workpiece of the present invention.

Figure 3 is a schematic diagram of the overall structure of the base installation of the present invention.

Figure 4 is a front view of the present invention.

Figure 5 is a schematic diagram of the structure of the rotating worktable.

In the picture: 1. Rotating table; 2. Lifting platform; 3. Forming components; 4. Laser printing device; 5. Feeding and leveling components; 6. Fixed base; 7. Turntable; 8. Base plate; 9. Telescopic protection Cover; 10, drive motor; 11, column; 12, vertical guide rail; 13, motor; 14, nut seat; 15, screw guide rail platform; 16, beam; 17, support platform; 18, guide rail; 19, slider 20. Transmission motor; 21. Dynamic powder cylinder model; 22. Parts to be formed; 23. Drive shaft; 24. Seal cover.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings:

As shown in Figures 1 to 4, an additive manufacturing device includes a rotating worktable 1, a lifting platform 2, a forming assembly 3, a laser printing device 4, and a feeding and leveling assembly 5;

The forming assembly 3, the laser printing device 4 and the feeding and leveling assembly 5 are all installed on the lifting platform 2 through the XY rail system, and the lifting platform 2 is driven to move along the Z axis through the Z rail system;

As shown in Figure 5, the rotary table 1 includes a fixed base 6 and a turntable 7. A base plate 8 is fixed on the turntable 7 and the turntable 7 can rotate relative to the fixed base 6; the turntable 7 can achieve any angle indexing movement with the Z axis as the rotation axis , Or continuous rotation action;

A retractable protective cover 9 is provided between the fixed base 6 and the lifting platform 2. The upper and lower ends of the retractable protective cover 9 are sealed and fixedly connected with the lifting platform 2 and the fixed base 6, respectively, the retractable protective cover 9, the fixed base 6 and the lifting platform A working sealed cavity is formed between 2 and the forming cavity. The printing head of the forming assembly 3, the printing head of the laser printing device 4 and the scraper part of the feeding and leveling assembly 5 are all located in the working sealed cavity;

The bottom of the lifting platform 2 is provided with a sealing cover 24. The sealing cover 24 adopts a flexible sealing cover. One end of the sealing cover 24 is sealed to the bottom of the lifting platform 2 and the other end of the sealing cover 24 is sealed and bonded to the side wall of the printing head of the forming assembly 3. 24 and the bottom of the lifting platform 2 form a seal space for the print head. The end of the seal cover 24 and the side wall of the print head can be sealed and bonded to move with the end of the print head. The flexibility of the seal cover prevents the leakage of inert gas in the working seal cavity; Yes, the printing head of the laser printing device 4 and the scraper part of the feeding and leveling assembly 5 are equipped with a sealing cover to prevent inert gas from connecting the forming assembly 3 and the lifting platform 2 through the gap during printing, and the laser printing device 4 is connected to the lifting platform 2 The gap or the gap between the feeding and leveling assembly 5 and the lifting platform 2 is missing;

The outer side of the fixed base 6 is provided with a connecting flange with the telescopic shield 9; the connecting flange is used to realize the sealed and fixed connection between the fixed base 6 and the telescopic shield 9; the drive shaft 23 penetrates the fixed base 6, and the drive shaft 23 is connected to the fixed base 6 Sealing between the base 6;

A drive motor 10 is provided at the lower end of the fixed base 6, and the drive motor 10 is connected to the turntable 7 through a drive shaft 23;

The Z-direction guide rail system includes columns 11 arranged on both sides of the lifting platform 2, a vertical rail 12 is provided on the side of the column 11 close to the lifting platform 2, the upper end of the column 11 is provided with a motor 13, and the output end of the motor 13 is fixed along the vertical For the lead screw provided by the guide rail 12, a nut is fixed on the side of the lifting platform 2 to cooperate with the lead screw; the nut is fixed on the side of the lifting platform 2 through a nut seat 14;

The forming component 3 uses one of the fused deposition forming (FDM) printing system, the laser near net shaping (LENS) printing system or the cold metal transfer welding system (CMT);

The bottom of the rotary table 1 is provided with an X-direction horizontal rail system. The X-direction horizontal rail system uses a screw rail platform 15. The screw rail platform 15 includes a support platform 17 and a guide rail 18 arranged on the support platform 17. The lower end of the rotary table 1 There is a sliding block 19 that cooperates with the guide rail 18 to slide. The screw guide rail platform 15 is provided with a transmission motor 20. The output end of the transmission motor 20 is connected to the transmission screw. The bottom of the rotary table 1 is provided with a transmission that cooperates with the transmission screw. Nut

The upright column 11 is fixed on the lead screw guide rail platform 15; the upper ends of the two upright columns 11 are provided with cross beams 16 to improve the stability of the overall device;

The XY rail system adopts a horizontal rail system, which can drive the forming assembly 3, the laser printing device 4 and the feeding and leveling assembly 5 to move horizontally on the lifting platform 2;

Precision grating rulers are installed on the XY rail system, X-direction horizontal rail system and Z-direction rail system to provide closed-loop feedback for movement to ensure the positioning accuracy and repeat positioning accuracy of its operation.

The forming assembly 3 is used to print on the substrate a dynamic powder cylinder model corresponding to the part to be formed during the forming process. The dynamic powder cylinder model is composed of a first side wall and a second side wall, and its overall shape and size are based on The shape characteristics of the parts to be processed are determined;

The laser printing device includes a QBH connector, a collimating beam expander module, a galvanometer and an f-θ field lens/dynamic focus lens, which is connected to the laser through an optical fiber. The laser printing device is used to realize the trajectory scanning of the surface of the powder bed during the SLM forming process; The printing device can move along the horizontal rail system, and a precision grating ruler is installed along the horizontal rail system to ensure the positioning accuracy and repeat positioning accuracy of the laser printing device movement; the laser printing device is integrally sealed in the optical system protective cover to prevent production during the forming process Smoke and metal powder contaminate the laser optical path system and cause adverse effects on laser transmission. 3D printing of metal materials, ceramic materials, and resin materials can be achieved by changing modular components such as laser type, feeding and leveling components, and dynamic forming cylinder forming components. Different forms, different numbers of laser types, feeding and leveling components, dynamic forming cylinder forming components, and different configurations can realize the additive forming of functionally graded materials. That is, the equipment can be applied to multiple materials and multiple forming processes, which greatly expands the application field of the equipment.

Example one:

(1) Generate the forming process parameter file of the part to be formed:

First, perform data processing according to the three-dimensional model of the toroidal part to be processed, generate SLM forming process files including slices, supports, scan paths, process parameters and scan strategies, and import process file data, equipment parameters and material parameter information into the process In the process numerical simulation software, the entire forming process is numerically simulated to obtain the deformation and stress warping deformation results during the forming process, and the anti-deformation prediction of the SLM forming process is generated by adding stress prevention, heat conduction auxiliary support and support structure optimization Model, regenerate the SLM forming process file for the obtained anti-deformation prediction model;

(2) Design the dynamic powder cylinder model corresponding to the part to be formed: determine the cross-sectional shape and size of the dynamic powder cylinder model according to the shape characteristics of the part to be formed. The shape feature of the part to be formed refers to the horizontal cross-sectional shape and size of the part to be formed. On the same forming horizontal section, the internal cavity of the dynamic powder cylinder model 21 forms a cavity pattern, and the part to be formed 22 forms a part pattern. The cavity pattern and the part pattern are similar patterns, and the dynamic powder cylinder model 21 will form the part to be formed 22 Contained in its internal cavity, that is, the to-be-formed part 22 is located in the forming area of the to-be-formed part formed by the first and second side walls and the base plate as the bottom surface; at the same time, the dynamic powder cylinder model 21 itself is required to have sufficient The strength is sufficient to carry the raw materials needed in the forming process of the part 22 to be formed; in a cross section of any height, the first and second side walls of the dynamic powder cylinder model 21 and the outer wall of the part 22 to be formed remain 5~ 10mm pitch; if the to-be-formed part 22 has a ring structure, the first side wall and the second side wall of the corresponding dynamic powder cylinder model 21 respectively form a closed ring; the annular area sandwiched by the two closed rings is the to-be-formed part 22 Forming area

(3) Generate the forming process parameter file of the dynamic powder cylinder model: perform data processing on the three-dimensional model of the dynamic powder cylinder model 21 obtained in step (2); the specific forming process of the dynamic powder cylinder model 21 can be selected as Fused Deposition Molding (FDM) ), laser near net shaping (LENS), cold metal transition welding technology (CMT) and other additive manufacturing forming processes; finally get the corresponding forming process parameter file of the dynamic powder cylinder model 21; this process parameter file Input equipment control system;

Generate a three-dimensional model of the dynamic powder cylinder model 21: use the additive manufacturing process to generate a layer of powder cylinder, the height of the powder cylinder meets the requirements of the SLM process to form a layer of part slices; the layer of powder cylinder is divided and set sequentially along its cross-sectional contour trajectory Several continuous areas are used for local powder spreading and SLM forming;

(4) Seal the forming cavity and replace the air in the forming area with inert gas;

(5) Form a section of dynamic powder cylinder model on the substrate: start forming component 3, use the set additive method, and form a section of dynamic powder cylinder model 21 on the substrate according to the set process parameters. The dynamic powder cylinder model 21 is a completely closed ring; the forming action of the dynamic powder cylinder model 21 is the rotation action of the rotary table, the radial movement (X axis) of the forming cylinder forming assembly 3, and the lifting action of the lifting platform 2 (Z axis) realized by linkage; each time the forming height of the dynamic powder cylinder model 21 is 10-20mm;

(6) Spread powder in the dynamic powder tank model: fix the scraper at the end of the powder spreader assembly 5, and then spread the powder inside the dynamic powder tank model 21 formed in step (5); where the height of the scraper is determined by The height of the lifting platform 2 is controlled. The powder spreading action of the scraper is realized by the rotation of the rotary table and the radial movement of the powder spreading assembly 5 in conjunction. During the powder spreading process, the scraper keeps moving inside the dynamic powder cylinder model 21, and excess powder will not overflow to the outside of the dynamic powder cylinder model 21.

(7) The workpiece is formed in the dynamic powder cylinder model: the laser printing device is started, and the powdered area is selectively melted and solidified according to the forming process parameters formulated in step (1).

(8) The lifting platform moves up to a height of layer thickness. When step (7) completes the printing and forming of the powder spreading area of one layer, move the lifting platform (3) up to a height of one layer thickness as a whole to prepare for powder spreading of the next layer.

(9) When the formed surface of the workpiece is 5-8mm away from the formed surface of the dynamic powder cylinder model, go to step (5) and start the forming assembly 3 to heighten the dynamic powder cylinder model 21. That is, it is ensured that during powder spreading and workpiece forming, the top of the dynamic powder cylinder model 21 is higher than the forming surface of the part 22 to be formed; in this way, excess powder will not overflow to the outside of the dynamic powder cylinder model 21 during powder spreading. . Then, perform step (6), step (7), step (8), and step (9) in sequence until the forming part 22 is completely formed. When the distance between the formed surface of the to-be-formed part 22 and the dynamic powder cylinder model 21 is greater than 5-8mm, skip to step (6) directly, and then follow step (7), step (8), and step (9) in sequence. Step) is performed until the entire to-be-formed part 22 is completely formed.

(10) After all the formed parts are formed, the retractable protective cover 9 is separated from the rotating table 1 and put away. Then lift the retractable protective cover 9 and the lifting platform 2 to the highest position. Finally, a forklift or other equipment is used to move the substrate 8 together with the dynamic powder cylinder model 21 fixed on it and the part to be formed 22 laterally out of the forming area, and send them to a specific location for post-processing such as cleaning and cutting.

The first embodiment mentioned above is formed according to the traditional single-layer slicing. During the forming of the dynamic powder cylinder model, the dynamic powder cylinder model is formed layer by layer or section by section in the longitudinal direction; in the horizontal direction, the internal cavity of the dynamic powder cylinder model forms a cavity pattern. The parts to be formed form part graphics, and the cavity graphics and the part graphics are similar graphics;

It is formed by layer-by-layer accumulation, and finally a complete workpiece is obtained. The powder spreading device is used to spread powder in the dynamic powder tank model while the rotating worktable rotates. The powder spreading device spreads the thickness of the first forming thickness; the powder spreading device makes a spiral upward movement relative to the part to be formed in the dynamic powder tank model; the scraper spreads powder At the same time, the worktable rotates, and the lifting platform synchronously lifts. Each time the worktable rotates, the lifting platform will lift a height of the powder spreading layer. The entire spatial trajectory of the scraper spreading powder is a spiral curve relative to the part to be formed; At the same time, the action requirements of the rotating table, lifting platform, and scraper are linked.

In the present invention, before forming the part to be formed, an additive forming method is used to form a cylinder as a container for accommodating the workpiece and forming materials. Because the size and shape of the cylinder change with the size and shape of the workpiece, it is called "Dynamic powder tank model".

Embodiment two:

(1) Generate the workpiece forming process parameter file: Carry out 3D modeling of the workpiece to be formed (or obtain the 3D model file of the workpiece from the service object), and then perform data processing. This data processing process can include one to several numerical simulation simulation processes. Finally, SLM forming process parameter files including slices, supports, scanning paths, and scanning strategies are generated. Input the process parameter file into the equipment control system.

(2) Design the dynamic powder cylinder model corresponding to the formed workpiece: it is required that the internal cavity of the dynamic powder cylinder model 21 forms a cavity pattern on the same forming horizontal section, and the part to be formed 22 forms a part pattern. The cavity pattern and the part pattern are Similar graphics, and the dynamic powder tank model 21 contains the to-be-formed part 22 inside, that is, the to-be-formed part 22 is located in the forming area of the to-be-formed part formed by the first side wall and the second side wall and the substrate as the bottom surface; The dynamic powder cylinder model 21 itself must have sufficient strength to carry the raw materials needed in the forming process of the part 22 to be formed. On a cross section of any height, the first side wall and the second side wall of the dynamic powder cylinder model 21 are kept at a distance of 5-10 mm from the side surface of the part 22 to be formed; if the part 22 to be formed has a ring structure, the corresponding dynamic powder The first side wall and the second side wall of the cylinder model 21 respectively form a closed ring, and the ring area sandwiched by the two closed rings is the forming area of the part 22 to be formed. Finally, a three-dimensional model of the dynamic powder tank model 21 is generated.

(3) Generate the forming process parameter file of the dynamic powder cylinder model: perform data processing on the three-dimensional model of the dynamic powder cylinder model 21 obtained in step (2). Finally, the corresponding forming process parameter file of the dynamic powder cylinder model 21 is obtained. Input the process parameter file into the equipment control system.

(4) Seal the forming area and replace the air in the forming area with inert gas.

(5) A section of dynamic powder cylinder model is formed on the substrate: the forming assembly is activated, and a section of the dynamic powder cylinder model 21 is formed on the substrate using the set additive method and the set process parameters. The formed dynamic powder cylinder model 21 is required to be a completely closed ring. The forming action of the dynamic powder cylinder model is realized by the rotation action of the rotating table, the radial movement of the forming cylinder forming assembly, and the lifting action of the lifting platform. The forming height of the dynamic powder cylinder model 21 is recommended to be 10-20mm each time.

(6) Spread powder in the dynamic powder tank model and simultaneously form the workpiece: select a scraper of appropriate size and fix it on the end of the powder spreading assembly, and then spread the powder inside the dynamic powder tank model 21 formed in step (5) . While the scraper is spreading powder (the worktable rotates), the lifting platform synchronously lifts. Every time the worktable rotates, the lifting platform will raise a height of the powder layer thickness. The entire spatial trajectory of the scraper spreading powder appears as a spirally rising curve.

(7) When the formed surface of the workpiece is 5-8mm away from the formed surface of the dynamic powder cylinder model, go to step (5), start the forming assembly, and heighten the dynamic powder cylinder model 21. That is, it is ensured that the top of the dynamic powder cylinder model 21 is higher than the forming surface of the to-be-formed part 22 during the powder spreading and the forming of the part 22 to be formed. In this way, the excess powder will not overflow to the outside of the dynamic powder cylinder model 21 during powder spreading. Then step (6) and step (7) are executed in sequence until the whole part 22 to be formed is completely formed.

(8) After the forming part 22 is completely formed, the retractable protective cover is separated from the rotating table and put away. Then raise the retractable protective cover and the lifting platform to the highest position. Finally, use a forklift or other equipment to move the substrate, the dynamic powder cylinder model 21 and the part to be formed 22 fixed on it, laterally out of the forming area, and send them to a specific location for post-processing such as cleaning and cutting.

Example three:

As shown in Figure 3. The two uprights are fixedly connected with a beam, which can improve the rigidity of the entire equipment frame structure. And the whole set of equipment is set on the supporting platform. A horizontal guide rail is provided on the supporting platform, and the rotating worktable can move horizontally along the guide rail.

When the workpiece is being formed, the rotating worktable is directly below the lifting platform, and the base of the rotating worktable and the supporting platform are in a position locked state.

When the workpiece is formed, the retractable protective cover is separated from the rotating table and put away. Then raise the retractable protective cover and the lifting platform to the highest position. Then, unlock the position of the rotary table. The rotating worktable, the base plate 8, the dynamic powder cylinder model 21, and the part to be formed 22 fixed on it are horizontally moved out of the forming area along the guide rail on the base. Finally, use cranes or forklifts and other lifting equipment to move the substrate, the dynamic powder cylinder model 21 and the parts to be formed 22 fixed on it to a specific location for post-processing such as cleaning and cutting.

Further, the rotary table can be set in the form of an exchange table. This can greatly shorten the loading and unloading time of the substrate and improve the efficiency of the equipment.

Embodiment four:

As shown in Figure 1. The laser galvanometer of the additive manufacturing equipment is set on the lifting platform. Set up multiple sets of laser printing devices on the lifting platform. Each laser printing device can independently perform radial movement on the lifting platform, allowing multiple laser printing devices to work on the same radius at the same time, improving the forming efficiency of the workpiece.

Embodiment five:

As shown in Figure 1 or Figure 3. The additive manufacturing equipment uses a retractable protective cover to connect the base of the rotating table and the lifting platform to form a closed atmosphere protection area. At the initial moment of forming, the lifting platform is at the lowest position and the forming area has the smallest volume. At this time, the inert gas is used to replace the air in the forming area. The time required is the shortest and the air consumption is the least (because the volume of replacement air is the smallest). During the forming of the workpiece, the lifting platform gradually rises, and the volume of the forming area continues to increase. In order to maintain the air pressure in the forming area slightly greater than the indoor air pressure, it is necessary to gradually increase the amount of inert gas injected.

Embodiment 6:

In order to form an atmosphere protection area, it is also possible to build an air-tight working room and place the entire main body of the additive manufacturing equipment in it. That is, the entire interior of the airtight working room serves as an atmosphere protection area. The volume of the atmosphere protection zone of this embodiment is basically constant from the initial moment of forming to the end of forming. However, when replacing air with inert gas, it takes a long time and consumes more air.

Embodiment Seven:

In order to improve the surface quality and dimensional accuracy of the finished product, when necessary, a material reduction processing device, such as a milling head and a grinding head, can be added under the lifting platform.

By replacing the feeding and leveling components, different raw materials such as powder, slurry, paste can be conveyed; and by replacing the laser, the input of different characteristic energy can be realized. Therefore, the additive molding of ceramic materials and resin materials can be realized. Different forms, different numbers of laser types, feeding and leveling components, dynamic forming cylinder forming components, constitute different configurations, which can realize metal/ceramic, metal/metal, ceramic/non-metal, non-metal/plastic, ceramic/ceramic, metal /Additive forming of non-metallic gradient functional composite materials.

Claims

An additive manufacturing device, which is characterized by comprising a rotating worktable (1), a lifting platform (2), a forming component (3), a laser printing device (4) and a feeding and leveling component (5);

The forming component (3), the laser printing device (4) and the feeding and leveling component (5) are all installed on the lifting platform (2) through the XY rail system, and the lifting platform (2) drives it along the Z axis through the Z rail system mobile;

The rotating workbench (1) includes a fixed base (6) and a turntable (7). A base plate (8) is fixed on the turntable (7), and the turntable (7) can rotate relative to the fixed base (6);

A retractable protective cover (9) is provided between the fixed base (6) and the lifting platform (2), and the upper and lower ends of the retractable protective cover (9) are respectively sealed and fixedly connected with the lifting platform (2) and the fixed base (6), A working sealed cavity is formed between the retractable protective cover (9), the fixed base (6) and the lifting platform (2);

The printing head of the forming assembly (3), the printing head of the laser printing device (4) and the scraper part of the feeding and leveling assembly (5) are all located in the working sealed cavity.
The additive manufacturing device according to claim 1, characterized in that a drive motor (10) is provided at the lower end of the fixed base (6), and the drive motor (10) is connected to the turntable (7) through a drive shaft (23) to drive The shaft (23) penetrates the fixed base (6), and the drive shaft (23) and the fixed base (6) are sealed.
The additive manufacturing device according to claim 1, wherein the Z-direction guide rail system includes uprights (11) arranged on both sides of the lifting platform (2), and the uprights (11) are close to the lifting platform (2). A vertical guide rail (12) is provided on the side, a motor (13) is provided at the upper end of the column (11), the output end of the motor (13) is fixed with a lead screw arranged along the vertical guide rail (12), and the lifting platform (2) is fixed on the side There are nuts for driving with the lead screw.
An additive manufacturing device according to claim 3, characterized in that the nut is fixed on the side of the lifting platform (2) through a nut seat (14).
The additive manufacturing device according to claim 1, wherein the forming component (3) is selected from one of a fused deposition forming printing system, a laser near net forming printing system, or a cold metal transfer welding system.
The additive manufacturing device according to claim 3, characterized in that the bottom of the rotating worktable (1) is provided with an X-direction horizontal rail system, and the X-direction horizontal rail system uses a screw rail platform (15).
An additive manufacturing device according to claim 6, characterized in that the lead screw guide rail platform (15) comprises a supporting platform (17) and a guide rail (18) arranged on the supporting platform (17), and a rotating worktable ( 1) The lower end is provided with a sliding block (19) that cooperates with the guide rail (18), and the screw guide rail platform (15) is provided with a transmission motor (20). The output end of the transmission motor (20) is connected to the transmission screw and rotates. The bottom of the platform (1) is provided with a transmission nut which is matched with the transmission screw for transmission.
A powder spreading method based on the additive manufacturing device of claim 1, characterized in that it comprises the following steps:

Step 1). First prepare the dynamic powder cylinder model of the part to be formed: remember that the two side walls of the internal cavity of the dynamic powder cylinder model are the first side wall and the second side wall, respectively. Finally closed in the horizontal direction to form the cross-sectional profile of the dynamic powder cylinder. The first and second side walls of the dynamic powder cylinder model and the base plate as the bottom surface constitute the forming area of the part to be formed; on the same horizontal section, the dynamic powder cylinder model The cavity forms a cavity pattern, the part to be formed forms a part pattern, and the cavity pattern and the part pattern are similar patterns;

Determine the cross-sectional shape and size of the dynamic powder cylinder model according to the shape characteristics of the part to be formed, and then use the additive forming method to prepare the dynamic powder cylinder model; during the forming process of the dynamic powder cylinder model, at any forming height, the dynamic powder cylinder model will The parts to be formed are wrapped in the dynamic powder cylinder model, and the dynamic powder cylinder model is formed to the initial height;

Step 2), and then rotate and spread powder in the dynamic powder tank model of the formed part, and perform SLM forming processing on the completed powder spread part. During the forming process, the powder surface of the formed part is always lower than the dynamic powder from the initial height. The molding surface of the cylinder model is 5-50mm.
The method for spreading powder according to claim 8, characterized in that, during the forming process, an inert gas is introduced into the retractable shield to form an inert atmosphere, and an additive manufacturing process is used to generate a layer of dynamic powder cylinder model ; The dynamic powder cylinder model of this layer is divided into several consecutive areas along its cross-sectional contour trajectory for local powder spreading and SLM forming.
The method of spreading powder according to claim 8, characterized in that, in step 2) during the forming process, a scraper is used to spread powder in the dynamic powder tank model while the rotating table rotates, and the thickness of the powder spreading device is equal to To form the thickness at one time; the powder spreading device makes a spiral upward movement relative to the part to be formed in the dynamic powder cylinder model; while the scraper spreads powder, the worktable rotates, and the lifting platform synchronously lifts. Each time the rotating worktable rotates, the lifting platform is It will raise a height of the powder spreading layer, and the entire space track of the scraper spreading powder is a spiral curve relative to the part to be formed; while the scraper spreads powder along the spiral track, the laser printing device sinters the powder spread area.