Device and method for powder bed additive manufacturing of rotational body gradient material

Abstract

The present invention relates to the technical field of powder bed additive manufacturing, and provides a device and method for powder bed additive manufacturing of gradient materials for rotating bodies. The device comprises a circular forming cylinder, a gradient powder supply and powder spreading unit, a forming unit and a control unit: the circular forming cylinder comprises an inner ring wall, an outer ring wall and a bottom wall, and can be lifted and lowered vertically; the gradient powder supply and powder spreading unit is used to form a powder layer with a set gradient in the radial direction and uniform distribution in the circumferential direction in the forming cylinder; the gradient powder supply and powder spreading unit can rotate relative to the circular forming cylinder; the forming unit is used to sinter or bond the set area of ​​the laid powder layer; the control unit controls the entire device. The method comprises the steps of powder supply, powder mixing, powder spreading and printing. The present invention can realize that the composition of each layer of powder of the rotating body changes continuously from the inner layer to the outer layer, and the gradient interval size is flexibly adjustable; the method of the present invention is simple and efficient, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of powder bed additive manufacturing, and in particular to a device and method for powder bed additive manufacturing of gradient materials for a rotating body. Background Art

[0002] Gradient materials refer to materials whose composition and structure gradually transition from one end of a component to the other, and whose performance and thermal properties and other parameters also gradually change accordingly, thus avoiding the interface problems of traditional composite materials. Among them, the gradient material of the body of revolution is a type of structure with high demand at present, such as the shell of the nuclear reactor pressure vessel, where the inner and outer layers are made of alloys with different corrosion resistance and strength respectively; for example, NASA has developed a new type of engine combustion chamber, where the inner layer is a high-temperature alloy to provide high strength, and the outer layer is made of copper alloy to improve the heat dissipation effect.

[0003] Additive manufacturing (AM) is a technology based on the principle of discrete stacking, which stacks materials layer by layer to prepare three-dimensional structural parts. Additive manufacturing technology, especially metal additive manufacturing technology, is currently a hot research topic. Among them, powder bed additive manufacturing technology, such as laser powder bed additive manufacturing technology and jet bonding technology, has the highest molding accuracy and good mechanical properties. Many researchers have improved powder bed additive manufacturing technology to prepare gradient materials, but most of them can only achieve gradient distribution in one or two directions, and it is difficult to achieve the preparation of gradient materials for rotating bodies. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and solve the problem that the current powder bed additive manufacturing technology is difficult to prepare the rotational body gradient material and cannot achieve the problem of stable and controllable radial gradient powder laying. Provided is a device and method for powder bed additive manufacturing of rotational body gradient materials, which can realize the preparation of high-performance interface-free rotational body gradient materials.

[0005] The present invention adopts the following technical solution:

[0006] On the one hand, the present invention provides a device for powder bed additive manufacturing of a rotating body gradient material, comprising a circular forming cylinder, a gradient powder supply and powder spreading unit, a forming unit and a control unit:

[0007] The annular forming cylinder comprises an inner annular wall, an outer annular wall and a bottom wall, forming a space with an upper opening; the annular forming cylinder can be lifted and lowered vertically;

[0008] The gradient powder supply and powder spreading unit is used to form a powder layer with a set gradient in the radial direction and uniform distribution in the circumferential direction in the annular forming cylinder; the gradient powder supply and powder spreading unit can rotate relative to the annular forming cylinder;

[0009] The molding unit is used to fuse or bond a set area of ​​the laid powder layer;

[0010] The control unit is used to control the relative rotation between the annular forming cylinder and the gradient powder supply and powder spreading unit, the vertical lifting of the annular forming cylinder, and the sintering or bonding of the forming unit.

[0011] According to any possible implementation described above, an implementation is further provided, wherein one end of the gradient powder supply and powder spreading unit is arranged at the center of the annular forming cylinder, and the other end extends to the outer ring wall of the annular forming cylinder; the specific manner in which the gradient powder supply and powder spreading unit rotates relative to the annular forming cylinder includes:

[0012] The annular forming cylinder remains stationary, and the gradient powder supply and powder spreading unit rotates around the center of the annular forming cylinder;

[0013] Alternatively, the gradient powder supply and powder spreading unit remains stationary, and the annular forming cylinder rotates around its own center.

[0014] According to any possible implementation described above, an implementation is further provided, wherein the gradient powder supply and powder spreading unit comprises a powder storage device, a quantitative powder supply device, a grid material trough, a powder mixer and a powder spreader from top to bottom; the powder spreading direction of the powder spreader is the circumferential direction of the annular forming cylinder, the moving direction of the powder storage device is the radial direction of the annular forming cylinder, and the vertical direction is the Z direction, wherein the circumferential direction of the annular forming cylinder, the radial direction of the annular forming cylinder and the Z direction are perpendicular to each other;

[0015] The number of the powder storage devices is two or more, and the powder storage devices are arranged side by side in a radial direction perpendicular to the annular forming cylinder, and the quantitative powder feeder for controlling the powder supply amount is arranged below each of the powder storage devices; the powder storage devices can move in the radial direction of the annular forming cylinder;

[0016] The grid trough is funnel-shaped and forms a grid in the radial direction of the annular forming cylinder; the grid funnel receives two or more powders from the quantitative powder feeder and forms a set gradient of each powder in the radial direction of the annular forming cylinder;

[0017] The powder mixer is arranged at the lower end of the grid material trough, and is used to evenly mix the powder from the grid material trough in the circumferential direction of the annular forming cylinder and maintain a set gradient in the radial direction of the annular forming cylinder;

[0018] The powder spreader is arranged below the powder mixer to receive powder from the powder mixer that has been evenly mixed along the circumference of the annular forming cylinder and maintains a set gradient along the radial direction of the annular forming cylinder; the powder spreader spreads powder along the circumference of the annular forming cylinder.

[0019] According to any possible implementation described above, there is further provided an implementation, wherein the gradient powder supply and powder spreading unit further comprises a powder storage device driving subunit, and the powder storage device driving subunit comprises a powder storage device fixing frame, a sliding guide rail and a driving motor;

[0020] The sliding guide rail is arranged radially along the annular forming cylinder, two or more powder storage devices are fixedly installed side by side on the powder storage device fixing frame, the powder storage device fixing frame is slidably connected to the sliding guide rail, and the driving motor drives the powder storage device fixing frame to move radially along the annular forming cylinder along the sliding guide rail.

[0021] As any possible implementation described above, there is further provided an implementation, wherein the molding unit is a laser module or a binder jetting module, which is used for sintering or bonding the powder layer, respectively.

[0022] According to any possible implementation described above, there is further provided an implementation, wherein the top of the grid trough is rectangular, the radial length of the top circular annular forming cylinder is the same as that of the sliding guide rail, and the circumferential width of the top circular annular forming cylinder is determined according to the size and number of the powder storage devices;

[0023] The inside of the grid trough is provided with equidistant partitions along the radial direction of the annular forming cylinder, and a grid is formed between adjacent partitions; when the powder storage fixed bracket moves along the movable guide rail, the starting position of the movement is the first grid, and each movement step is a grid spacing.

[0024] On the other hand, the present invention also provides a method for powder bed additive manufacturing of a rotating body gradient material, the method using the above-mentioned device for powder bed additive manufacturing of a rotating body gradient material, the annular forming cylinder of the device remains stationary, and the gradient powder supply and powder spreading unit can rotate around the center of the annular forming cylinder;

[0025] The method specifically comprises:

[0026] S1. Two or more powder storage containers are fixed side by side on a powder storage container fixing frame, and different powder storage containers contain different types of powders;

[0027] S2, the gradient powder supply and powder spreading unit is in the initial position; the initial position of the powder storage is the first grid of the grid trough, and the step length of each movement of the powder storage along the radial direction of the annular forming cylinder is one grid spacing; each powder storage supplies different amounts of powder to the current grid of the grid trough through the quantitative powder feeder according to its own settings, and then controls the powder storage to move to the next grid, repeating the powder supply action until all grids are completed, that is, the powder ratio is realized along the radial direction of the annular forming cylinder. Gradient change;

[0028] S3, the powder mixer receives the powder from the grid trough, mixes the powder evenly in the circumferential direction of the annular forming cylinder, and maintains the set gradient in the radial direction of the annular forming cylinder;

[0029] S4, the powder spreader receives the powder from the powder mixer, rotates around the center of the annular forming cylinder, and spreads the gradient powder on the annular forming cylinder; the powder ratio changes along the radial direction of the annular forming cylinder and is evenly distributed along the circumference of the annular forming cylinder;

[0030] S5, laser scanning the set area of ​​the molding cylinder powder layer to complete the sintering printing of the current layer of the part; or the binder spraying the set area of ​​the molding cylinder powder layer to complete the bonding printing of the current layer of the part;

[0031] S6. Repeat steps S2-S5 until all layers of the part are printed. By controlling the composition ratio of each layer of powder along the radial direction of the circular forming cylinder and the composition ratio of different layers of powder along the Z direction, a continuous and controllable gradient distribution of the part in the (radial-Z) dimension is achieved.

[0032] On the other hand, the present invention also provides a method for powder bed additive manufacturing of a rotating body gradient material, the method using the above-mentioned device for powder bed additive manufacturing of a rotating body gradient material, the annular forming cylinder of the device remains stationary, the gradient powder supply and powder spreading unit remains stationary, and the annular forming cylinder can rotate around its own center;

[0033] The method specifically comprises:

[0034] S1. Two or more powder storage containers are fixed side by side on a powder storage container fixing frame, and different powder storage containers contain different types of powders;

[0035] S2, the gradient powder supply and powder spreading unit is in the initial position; the initial position of the powder storage is the first grid of the grid trough, and the step length of each movement of the powder storage along the radial direction of the annular forming cylinder is one grid spacing; each powder storage supplies different amounts of powder to the current grid of the grid trough through the quantitative powder feeder according to its own settings, and then controls the powder storage to move to the next grid, repeating the powder supply action until all grids are completed, that is, the powder ratio is realized along the radial direction of the annular forming cylinder. Gradient change;

[0036] S3, the powder mixer receives the powder from the grid trough, mixes the powder evenly in the circumferential direction of the annular forming cylinder, and maintains the set gradient in the radial direction of the annular forming cylinder;

[0037] S4, the powder spreader receives the powder from the powder mixer, the annular forming cylinder rotates around its own center, and the fixed powder spreader spreads the gradient powder on the annular forming cylinder; the powder ratio changes along the radial direction of the annular forming cylinder and is evenly distributed along the circumference of the annular forming cylinder;

[0038] S5, laser scanning the set area of ​​the molding cylinder powder layer to complete the sintering printing of the current layer of the part; or the binder spraying the set area of ​​the molding cylinder powder layer to complete the bonding printing of the current layer of the part;

[0039] S6. Repeat steps S2-S5 until all layers of the part are printed. By controlling the composition ratio of each layer of powder along the radial direction of the circular forming cylinder and the composition ratio of different layers of powder along the Z direction, a continuous and controllable gradient distribution of the part in the (radial-Z) dimension is achieved.

[0040] As for any possible implementation described above, there is further provided an implementation, in which the step length and grid spacing of each movement of the powder storage device along the radial direction of the annular forming cylinder are both 1 mm.

[0041] Any possible implementation as described above further provides an implementation in which the amount of powder in each grid is determined by the thickness of the powder layer, the gradient ratio of the current position, and the distance between the current position and the center of the annular forming cylinder.

[0042] The beneficial effects of the present invention are:

[0043] The method of the present invention sets the molding area as a circular ring, and the powder spreading device performs a circular motion around the center of the circle; the powder spreading device can also be fixed, and the molding substrate moves around the center of the circle. The powder supply device can provide gradient powder distributed in the radial direction to the powder spreader, and the gradient powder is evenly spread on the molding area during the circular motion of the powder spreading device (or the circular motion of the annular molding cylinder), so that the composition of each layer of powder changes continuously from the inner layer to the outer layer, and the gradient interval size is flexibly adjustable. After the gradient powder is spread, it is formed by scanning a high-energy beam or spraying a binder in a specific area to achieve the preparation of a rotating body gradient material. The method of the present invention is simple and efficient, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Shown is a schematic structural diagram of a device for powder bed additive manufacturing of gradient materials for a rotating body according to an embodiment of the present invention.

[0045] Figure 2 Shown is a schematic structural diagram of the gradient powder supply and powder spreading unit in the embodiment.

[0046] Figure 3 The figure shows a side view of the gradient powder supply and powder spreading unit in the embodiment.

[0047] Figure 4 Shown is a front view schematic diagram of the gradient powder supply and powder spreading unit in the embodiment.

[0048] Figure 5 Shown is a schematic top view of the grid trough in the embodiment.

[0049] In the figure: 1- gradient powder supply and powder spreading unit; 2- annular forming cylinder (including inner ring wall and outer ring wall); 3- (gradient) powder layer; 11- powder storage fixed frame; 12- powder storage; 13- quantitative powder supply; 14- grid material trough; 15- powder mixing drum; 16- powder spreading device; 17- sliding guide rail; 18- driving motor; 19- workbench. Two or more powder storages can be set according to actual needs, and each powder storage contains different alloy powders, which are commonly used 3D printing powders. DETAILED DESCRIPTION

[0050] The specific embodiments of the present invention will be described in detail below in conjunction with specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0051] An embodiment of the present invention is a device for powder bed additive manufacturing of a rotating body gradient material, comprising a circular ring forming cylinder 2, a gradient powder supply and powder spreading unit 1, a forming unit and a control unit: the circular ring forming cylinder 2 comprises an inner ring wall, an outer ring wall and a bottom wall, forming a space with an upper opening; the circular ring forming cylinder 2 can be lifted and lowered vertically; the gradient powder supply and powder spreading unit 1 is used to form a powder layer with a set gradient in the radial direction and uniform distribution in the circumferential direction in the circular ring forming cylinder 2; the gradient powder supply and powder spreading unit 1 can rotate relative to the circular ring forming cylinder 2; the forming unit is used to sinter or bond a set area of ​​the laid powder layer; the control unit is used to control the relative rotation between the circular ring forming cylinder 2 and the gradient powder supply and powder spreading unit 1, the vertical lifting and lowering of the circular ring forming cylinder 2, and the sintering or bonding of the forming unit.

[0052] For the convenience of expression, the center of the circular forming cylinder 2 is set to O, the radius of the inner ring wall is r1, the radius of the outer ring wall is r2, and the coordinate system R-θ-Z is set with the center of the ring O, wherein R-θ is a horizontal plane, R is located on the outer ring wall, OR is a radial direction (moving direction of the powder storage device), and OR is set as the initial position, θ is the rotation direction (i.e., the powder spreading direction of the powder spreader), and Z is the vertical direction.

[0053] like Figure 1 As shown, in a specific embodiment, the gradient powder supply and powder spreading unit 1 is placed above the processing plane; one end of the gradient powder supply and powder spreading unit 1 is arranged at the center (O) of the annular forming cylinder 2, and the other end extends to the outer ring wall (R) of the annular forming cylinder 2.

[0054] The gradient powder supply and powder spreading unit 1 includes a powder storage 12, a quantitative powder supply 13, a grid material trough 14, a powder mixer (powder mixing roller 15) and a powder spreader 16 from top to bottom; the powder spreading direction of the powder spreader 16 is the circumferential direction of the annular forming cylinder 2, the moving direction of the powder storage 12 is the radial direction of the annular forming cylinder 2, and the vertical direction is the Z direction, wherein the circumferential direction, radial direction and Z direction of the annular forming cylinder 2 are perpendicular to each other. The gradient powder supply and powder spreading unit 1 also includes a powder storage drive subunit, and the powder storage drive subunit includes a powder storage fixed frame 11, a sliding guide rail 17 and a driving motor 18; the sliding guide rail 17 is arranged radially, two or more powder storages 12 are fixedly installed side by side on the powder storage fixed frame 11, the powder storage fixed frame 11 is slidably connected to the sliding guide rail 17, and the driving motor 18 drives the powder storage fixed frame 11 to move radially along the annular forming cylinder 2 along the sliding guide rail 17.

[0055] In a specific embodiment, one end of the powder spreader 16 is fixed at the center of the circle O, and the other end is located on the outer ring wall. The powder spreader 16 moves in a circle around the center of the circle, and its movement direction is clockwise. Figure 1 In this embodiment, the annular forming cylinder 2 remains stationary, and the gradient powder supply and powder spreading unit 1 rotates around the center (center of the circle) of the annular forming cylinder 2 .

[0056] Figure 2-Figure 4 They are the top view, side view and front view of the gradient powder supply and powder spreading unit respectively.

[0057] In another specific embodiment, the gradient powder supply and powder spreading unit 1 remains stationary, and the annular forming cylinder 2 rotates around its own center.

[0058] In a specific embodiment, a plurality of powder storage containers 12 are fixed on a powder storage container fixing frame 11, and a quantitative powder feeder 13 is provided at the bottom of the powder storage container 12. Powder can flow out through the quantitative powder feeder 13 into a grid trough 14, and the powder supply is ensured by the number of times the quantitative powder feeder 13 is opened.

[0059] The grid trough 14 is located at the lower end of the powder storage device 12 and the sliding guide rail 17, and is used to receive the powder supplied by the quantitative powder feeder 13. The grid trough 14 is funnel-shaped from top to bottom as a whole, and the top is rectangular. The length in the OR direction is the same as that of the sliding guide rail 17, and the length perpendicular to the OR direction can be set according to the actual number of powder storage devices 12, that is, longer than the length of multiple powder storage devices 12 arranged in parallel perpendicular to the OR direction, to ensure that the powder flowing out of the quantitative powder feeder 13 can flow into the grid trough 14; equidistant partitions are arranged inside the grid trough 14 along the OR direction. When the powder storage device fixing frame 11 moves along the sliding guide rail 17, the starting position of the movement is the first grid, and the step length of each movement is one grid distance. Each time it stops on a grid, each powder storage device 12 supplies different amounts of powder to the current grid through the quantitative powder feeder 13 according to its own settings, and then the driving motor 18 controls the powder storage device 12 to move to the next grid.

[0060] The amount of powder in each grid is determined by the thickness of the powder layer, the gradient ratio of the current position, and the distance between the current position and the center of the circle.

[0061] In a specific embodiment, the size of the quantitative powder feeder 13 corresponds to the size of the grid trough 14. The length of the grid trough 14 along the direction perpendicular to the OR direction is N mm. The purpose of the grid trough 14 is to divide the entire powder layer into multiple areas along the OR direction for separate powder supply, and is set to p1, p2, p3, .. . pn. The width of each grid or area is 1 mm. According to the gradient change ratio of the layer of powder along the OR direction, the number of times each quantitative powder feeder 13 is opened in each grid is determined, that is, the ratio and total amount of the components at the corresponding position. Figure 5 1 is a top view of the grid trough 14. The width of a single area in the grid trough 14 determines the accuracy of the gradient ratio change.

[0062] In a specific embodiment, the powder enters the powder mixing drum 15 after passing through the grid trough 14. The powder mixing drum 15 is horizontally placed and rotates around the OR axis, so that the powder is fully mixed in the direction perpendicular to the OR and still maintains a preset gradient in the OR direction.

[0063] In a specific embodiment, the powder is mixed by the powder mixing drum 15 and then enters the powder spreader 16, which moves in a circle around the center O to spread the gradient powder on the powder bed of the forming cylinder. Before laying the next layer of powder, the annular forming cylinder 2 descends a specific layer thickness distance.

[0064] The gradient change ratio of each layer of powder along the radial direction can be set individually, so as to achieve a gradient with any directional ratio on the (radial-Z) plane of the printed part.

[0065] In a specific embodiment, the forming unit is a laser module for sintering the powder layer.

[0066] In another specific embodiment, the molding unit is a binder injection module for bonding the powder layer.

[0067] The embodiment of the present invention provides a method for powder bed additive manufacturing of a rotating body gradient material, the method using the device for powder bed additive manufacturing of a rotating body gradient material as described above, the annular forming cylinder 2 of the device remains stationary, and the gradient powder supply and powder spreading unit 1 can rotate around the center of the annular forming cylinder 2;

[0068] The method specifically comprises:

[0069] S1, two or more powder storage containers 12 are fixed side by side on a powder storage container fixing frame 11, and different powder storage containers 12 contain different types of powders respectively;

[0070] S2, the gradient powder supply and powder spreading unit 1 is in the initial position; the initial position of the powder storage 12 is the first grid of the grid trough 14, and the step length of each movement of the powder storage 12 along the radial direction of the annular forming cylinder 2 is one grid spacing; each powder storage 12 supplies different amounts of powder to the current grid of the grid trough 14 through the quantitative powder supply 13 according to its own settings, and then controls the powder storage 12 to move to the next grid, repeats the powder supply action until all grids are completed, that is, the powder ratio is realized along the radial gradient change of the annular forming cylinder 2;

[0071] S3, the powder mixer (powder mixing drum 15) receives the powder from the grid trough 14, mixes the powder evenly in the circumferential direction of the annular forming cylinder 2, and maintains a set gradient in the radial direction of the annular forming cylinder 2;

[0072] S4, the powder spreader 16 receives the powder from the powder mixer 15, and the powder spreader 16 rotates around the center of the annular forming cylinder 2 to spread the gradient powder on the annular forming cylinder 2; the powder ratio changes along the radial direction of the annular forming cylinder 2 and is evenly distributed along the circumference of the annular forming cylinder 2;

[0073] S5, laser scanning the set area of ​​the molding cylinder powder layer to complete the sintering printing of the current layer of the part; or the binder spraying the set area of ​​the molding cylinder powder layer to complete the bonding printing of the current layer of the part;

[0074] S6. Repeat steps S2-S5 until all layers of the part are printed. By controlling the composition ratio of each layer of powder along the radial direction of the annular forming cylinder 2 and the composition ratio of different layers of powder along the Z direction, a continuous and controllable gradient distribution of the part in the (radial-Z) dimension is achieved.

[0075] In another embodiment, the gradient powder supply and powder spreading unit of the device remains stationary, and the annular forming cylinder can rotate around its own center.

[0076] Example

[0077] This embodiment takes the laser powder bed fusion additive manufacturing technology as an example. The gradient powder supply and powder spreading unit 1 is fixed, the forming cylinder 2 and the cylinder wall move in a circle around the center of the circle, and the laser scanning area is set to the upper left 1 / 4 sector area.

[0078] Two kinds of powders are used for printing, namely A powder and B powder, which are placed in the powder storage container 12.

[0079] Determine the gradient ratio distribution of each layer of the rotating body, that is, the gradient ratio change from each layer to the last nth layer of powder.

[0080] Printing starts, and according to the setting of the first layer powder gradient ratio, each powder storage 2 and the quantitative powder supply 13 supplies powders of different ratios along the OR direction.

[0081] The powder enters the powder mixer 15 through the grid trough 14 and is mixed in a direction perpendicular to the OR direction, maintaining a predetermined gradient ratio in the OR direction.

[0082] The powder falls into the powder spreader 16, which is controlled to move in a circle around the center of the circle. Every 90-degree rotation, the laser scans a specific area to melt and solidify the metal powder. Then, the powder spreader 16 rotates 90 degrees and then the laser scans the specific area. After rotating 360 degrees, the current layer scan is completed, and the annular forming cylinder 2 descends a specific layer thickness.

[0083] The above steps of powder supplying, powder mixing, powder spreading and printing are repeated, wherein in the step of supplying each layer of powder, the powder storage device 12 and the quantitative powder supply device 13 supply powder along the OR direction according to the current layer gradient ratio until the printing is completed.

[0084] The method of the present invention can make the same layer of gradient powder have the same composition on the circumference of each radius and the same gradient distribution in each radial direction from the inner ring wall to the outer ring wall of the annular forming cylinder 2. Furthermore, by changing the composition ratio of different layers, a continuous and controllable gradient distribution can be achieved in the Z dimension.

[0085] Although several embodiments of the present invention have been given herein, those skilled in the art should understand that the embodiments of the present invention may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. A device for powder bed additive manufacturing of a rotating body gradient material, characterized in that: The device comprises a circular forming cylinder, a gradient powder supply and powder spreading unit, a forming unit and a control unit: The annular forming cylinder comprises an inner annular wall, an outer annular wall and a bottom wall, forming a space with an upper opening; the annular forming cylinder can be lifted and lowered vertically; The gradient powder supply and powder spreading unit is used to form a powder layer with a set gradient in the radial direction and uniform distribution in the circumferential direction in the annular forming cylinder; the gradient powder supply and powder spreading unit can rotate relative to the annular forming cylinder; The molding unit is used to fuse or bond a set area of ​​the laid powder layer; The control unit is used to control the relative rotation between the annular forming cylinder and the gradient powder supply and powder spreading unit, the vertical lifting of the annular forming cylinder, and the sintering or bonding of the forming unit; One end of the gradient powder supply and powder spreading unit is arranged at the center of the annular forming cylinder, and the other end extends to the outer ring wall of the annular forming cylinder; the specific manner in which the gradient powder supply and powder spreading unit rotates relative to the annular forming cylinder includes: The annular forming cylinder remains stationary, and the gradient powder supply and powder spreading unit rotates around the center of the annular forming cylinder; Alternatively, the gradient powder supply and powder spreading unit remains stationary, and the annular forming cylinder rotates around its own center; The gradient powder supply and powder spreading unit comprises a powder storage device, a quantitative powder supply device, a grid material trough, a powder mixer and a powder spreader from top to bottom; the powder spreading direction of the powder spreader is the circumferential direction of the annular forming cylinder, the moving direction of the powder storage device is the radial direction of the annular forming cylinder, and the vertical direction is the Z direction, wherein the circumferential direction of the annular forming cylinder, the radial direction of the annular forming cylinder and the Z direction are perpendicular to each other; The number of the powder storage devices is two or more, and the powder storage devices are arranged side by side in a radial direction perpendicular to the annular forming cylinder, and the quantitative powder feeder for controlling the powder supply amount is arranged below each of the powder storage devices; the powder storage devices can move in the radial direction of the annular forming cylinder; The grid trough is funnel-shaped and forms a grid in the radial direction of the annular forming cylinder; the grid trough receives two or more powders from the quantitative powder feeder and forms a set gradient of each powder in the radial direction of the annular forming cylinder; The powder mixer is arranged at the lower end of the grid material trough, and is used to evenly mix the powder from the grid material trough in the circumferential direction of the annular forming cylinder and maintain a set gradient in the radial direction of the annular forming cylinder; The powder spreader is arranged below the powder mixer to receive powder from the powder mixer that has been evenly mixed along the circumference of the annular forming cylinder and maintains a set gradient along the radial direction of the annular forming cylinder; the powder spreader spreads powder along the circumference of the annular forming cylinder.

2. The device for powder bed additive manufacturing of a rotating body gradient material according to claim 1, characterized in that: The gradient powder supply and powder spreading unit further comprises a powder storage device driving subunit, wherein the powder storage device driving subunit comprises a powder storage device fixing frame, a sliding guide rail and a driving motor; The sliding guide rail is arranged radially along the annular forming cylinder, two or more powder storage devices are fixedly installed side by side on the powder storage device fixing frame, the powder storage device fixing frame is slidably connected to the sliding guide rail, and the driving motor drives the powder storage device fixing frame to move radially along the annular forming cylinder along the sliding guide rail.

3. The device for powder bed additive manufacturing of a rotating body gradient material according to claim 1, characterized in that: The molding unit is a laser module or a binder jetting module, which is used for sintering or bonding the powder layer respectively.

4. The device for powder bed additive manufacturing of a rotating body gradient material according to claim 2, characterized in that: The top of the grid trough is rectangular, the radial length of the top along the annular forming cylinder is the same as that of the sliding guide rail, and the circumferential width of the top along the annular forming cylinder is determined according to the size and number of the powder storage devices; The inside of the grid trough is provided with equidistant partitions along the radial direction of the annular forming cylinder, and a grid is formed between adjacent partitions; when the powder storage fixed bracket moves along the sliding guide rail, the starting position of the movement is the first grid, and each movement step is a grid spacing.

5. A method for powder bed additive manufacturing of a gradient material of a rotating body, characterized in that: The method uses the device for powder bed additive manufacturing of rotating body gradient material according to any one of claims 1 to 4, wherein the annular forming cylinder of the device remains stationary, and the gradient powder supply and powder spreading unit can rotate around the center of the annular forming cylinder; The method specifically comprises: S1. Two or more powder storage containers are fixed side by side on a powder storage container fixing frame, and different powder storage containers contain different types of powders; S2, the gradient powder supply and powder spreading unit is in the initial position; the initial position of the powder storage is the first grid of the grid trough, and the step length of each movement of the powder storage along the radial direction of the annular forming cylinder is one grid spacing; each powder storage supplies different amounts of powder to the current grid of the grid trough through the quantitative powder feeder according to its own settings, and then controls the powder storage to move to the next grid, repeating the powder supply action until all grids are completed, that is, the powder ratio is realized along the radial direction of the annular forming cylinder. Gradient change; S3, the powder mixer receives the powder from the grid trough, mixes the powder evenly in the circumferential direction of the annular forming cylinder, and maintains the set gradient in the radial direction of the annular forming cylinder; S4, the powder spreader receives the powder from the powder mixer, rotates around the center of the annular forming cylinder, and spreads the gradient powder on the annular forming cylinder; the powder ratio changes along the radial direction of the annular forming cylinder and is evenly distributed along the circumference of the annular forming cylinder; S5, laser scanning the set area of ​​the molding cylinder powder layer to complete the sintering printing of the current layer of the part; or the binder spraying the set area of ​​the molding cylinder powder layer to complete the bonding printing of the current layer of the part; S6. Repeat steps S2-S5 until all layers of the part are printed. By controlling the composition ratio of each layer of powder along the radial direction of the annular forming cylinder and the composition ratio of different layers of powder along the Z direction, a continuously controllable gradient distribution of the part in the radial dimension of the Z axis is achieved.

6. The method for powder bed additive manufacturing of a gradient material for a body of revolution as claimed in claim 5, characterized in that: The step length and grid spacing of each movement of the powder storage device along the radial direction of the circular forming cylinder are both 1mm.

7. The method for powder bed additive manufacturing of a gradient material for a body of revolution as claimed in claim 5, characterized in that: The amount of powder in each grid is determined by the thickness of the powder layer, the gradient ratio of the current position and the distance between the current position and the center of the annular forming cylinder.

8. A method for powder bed additive manufacturing of a gradient material of a rotating body, characterized in that: The method uses the device for powder bed additive manufacturing of rotating body gradient material according to any one of claims 1 to 4, wherein the annular forming cylinder of the device remains stationary, the gradient powder supply and powder spreading unit remains stationary, and the annular forming cylinder can rotate around its own center; The method specifically comprises: S1. Two or more powder storage containers are fixed side by side on a powder storage container fixing frame, and different powder storage containers contain different types of powders; S2, the gradient powder supply and powder spreading unit is in the initial position; the initial position of the powder storage is the first grid of the grid trough, and the step length of each movement of the powder storage along the radial direction of the annular forming cylinder is one grid spacing; each powder storage supplies different amounts of powder to the current grid of the grid trough through the quantitative powder feeder according to its own settings, and then controls the powder storage to move to the next grid, repeating the powder supply action until all grids are completed, that is, the powder ratio is realized along the radial direction of the annular forming cylinder. Gradient change; S3, the powder mixer receives the powder from the grid trough, mixes the powder evenly in the circumferential direction of the annular forming cylinder, and maintains the set gradient in the radial direction of the annular forming cylinder; S4, the powder spreader receives the powder from the powder mixer, the annular forming cylinder rotates around its own center, and the fixed powder spreader spreads the gradient powder on the annular forming cylinder; the powder ratio changes along the radial direction of the annular forming cylinder and is evenly distributed along the circumference of the annular forming cylinder; S5, laser scanning the set area of ​​the molding cylinder powder layer to complete the sintering printing of the current layer of the part; or the binder spraying the set area of ​​the molding cylinder powder layer to complete the bonding printing of the current layer of the part; S6. Repeat steps S2-S5 until all layers of the part are printed. By controlling the composition ratio of each layer of powder along the radial direction of the annular forming cylinder and the composition ratio of different layers of powder along the Z direction, a continuously controllable gradient distribution of the part in the radial dimension of the Z axis is achieved.

9. The method for powder bed additive manufacturing of a gradient material for a body of revolution as claimed in claim 8, characterized in that: The step length and grid spacing of each movement of the powder storage device along the radial direction of the circular forming cylinder are both 1mm.

10. The method for powder bed additive manufacturing of a rotating body gradient material according to claim 8, characterized in that: The amount of powder in each grid is determined by the thickness of the powder layer, the gradient ratio of the current position and the distance between the current position and the center of the annular forming cylinder.

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