Laser continuous scanning method for rotating platform laser powder bed additive manufacturing

Abstract

The present application relates to the field of powder bed additive manufacturing technology, and provides a laser continuous scanning method for a rotating platform laser powder bed additive manufacturing, the method comprising: a circular ring platform is equally divided into a plurality of fan-shaped micro-zones with the same size; the scanning path of the laser is a straight line reciprocation, scanning from the outer ring of the circular ring platform to the inner ring, and returning to the outer ring from the inner ring is empty jump; the circular ring platform rotates at a certain angular velocity w, and the laser continuously scans the powder layer on the circular ring platform at a certain linear velocity v according to the path set in step S2. The method can be applied to the preparation of gradient rotation body parts. The present application can realize the dense scanning of the current powder layer during the movement of the circular ring platform, and the laser center only needs to scan on a line, and the rotation speed of the circular ring platform is adjusted to realize the coupling with the laser process parameters; the present application can be particularly applied to the preparation of gradient rotation body parts, and has good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of powder bed additive manufacturing technology, in particular to a laser continuous scanning method and application for laser powder bed additive manufacturing of a rotating platform. BACKGROUND

[0002] The laser powder bed additive manufacturing technology is a new metal part preparation technology in recent years, which uses metal powder as raw material, laser beam as heat source, and uses the principle of discrete accumulation to prepare metal components by layering and accumulating metal powder. It can realize near-net shaping of metal parts and has broad application prospects in aerospace, medical treatment, energy and other fields.

[0003] At present, the forming platform used in this technology is mostly square, and only moves vertically in the Z-axis direction. For large-sized rotary parts or rotary gradient materials, the square forming platform has certain limitations for such parts due to the limitation of laser scanning range or the limitation of component distribution control. The circular ring forming platform can realize the preparation of large-sized rotary parts by relying on the continuous rotation of the forming platform, and can avoid the problem of small laser scanning range by relying on the rotation of the powder bed. However, the circular ring forming platform includes not only the vertical movement along the Z-axis direction, but also the circumferential movement around the center of the circle. Therefore, how to coordinate the laser process and the platform speed to realize the dense scanning of the current powder layer during the real-time circumferential movement of the circular ring forming platform is a key problem of this forming method. SUMMARY

[0004] The technical problem solved by the present application is:

[0005] During the movement of the rotary forming platform, the rotational linear speed on different radius circles is different. When the rotary forming platform maintains rotational movement, the laser scanning mode is difficult to match.

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, and provide a laser continuous scanning method and application for laser powder bed additive manufacturing of a rotating platform. By adjusting the speed of the forming platform, the diameter of the laser spot and the laser scanning speed, the dense scanning of the scanning area is realized.

[0007] The present application adopts the following technical solutions:

[0008] On the one hand, the present application provides a laser continuous scanning method for laser powder bed additive manufacturing of a rotating platform. The rotating platform is a circular ring platform, and the method comprises:

[0009] S1, the circular ring platform is divided into a plurality of fan-shaped micro-zones with the same size; the width of each fan-shaped micro-zone is D1 at the inner ring of the circular ring platform, and the width of each fan-shaped micro-zone is D2 at the outer ring of the circular ring platform;

[0010] S2, the scanning path of the laser is a straight reciprocating line, scanning from the outer ring of the circular ring platform to the inner ring; the laser does not emit light (empty jump) when returning from the inner ring to the outer ring; the spot diameter of the laser at the outer ring is R2≥D2, and the spot diameter of the laser at the inner ring is R1≥D1; the spot diameter of the laser continuously changes from large to small during scanning, and the laser spot scans one sector micro area each time;

[0011] S3, the circular ring platform rotates at a certain angular velocity w, and the laser continuously scans the powder layer on the circular ring platform according to the path set in step S2 at a certain linear velocity v.

[0012] According to any possible implementation manner described above, further provided is an implementation manner, in step S2, the scanning path of the laser is determined by the following method:

[0013] In the three adjacent sector micro areas, the starting point of laser scanning is the midpoint of the outer ring of the middle sector micro area, and the ending point of laser scanning is the midpoint of the inner ring of the adjacent sector micro area in the rotation direction of the circular ring platform; the laser reciprocates along the connecting line between the starting point and the ending point.

[0014] According to any possible implementation manner described above, further provided is an implementation manner, the inner ring radius of the circular ring platform is r1, and the outer ring radius is r2; in step S2, at any scanning position, the ratio of the laser spot diameter R to R2 is equal to the ratio of the current position to the outer ring radius r2.

[0015] According to any possible implementation manner described above, further provided is an implementation manner, in step S3, the determination method of the laser scanning linear velocity v, the circular ring platform rotation angular velocity w and the sector micro area size is as follows:

[0016] S3.1, the laser scanning linear velocity v and the laser overlap rate H are determined according to the powder layer material and the powder layer thickness, the range is (0-100%), which represents the angle of the overlap of two adjacent sectors; then the included angle θ between the center lines of two sector micro areas can be obtained according to the relationship of formula (1):

[0017] θ=2(1-H)arcsin(R1 / r1) (1);

[0018] S3.2, the scanning distance X from the starting point to the ending point of laser scanning is determined:

[0019]

[0020] S3.3, the time t required for one-way reciprocating scanning of the laser is determined:

[0021] t=X / v (3);

[0022] S3.4 Determine the circular platform rotation angular velocity w:

[0023] w = (θ * X) / v (4).

[0024] As any possible implementation manner described above, further provides an implementation manner, the additive is one or several kinds of metal powder.

[0025] As any possible implementation manner described above, further provides an implementation manner, when the prepared part has a specific shape, first, the part is sliced and analyzed, and the to-be-scanned melting area of each powder layer is determined;Then when scanning each powder layer, the laser only emits light in the to-be-scanned melting area, and does not emit light in the non-to-be-scanned melting area, to complete the laser scanning of the powder layer.

[0026] In another aspect, the application also provides an application of the above-mentioned laser continuous scanning method for laser powder bed additive manufacturing of a rotating platform in the preparation of a gradient revolution body part, the gradient revolution body part includes two or more kinds of powder, and the gradient revolution body part is formed on a circular rotating platform, and the proportion of each powder in the gradient revolution body part is set to be gradient in the radial direction of the circular ring where the gradient revolution body part is located and uniform in the circumferential direction.

[0027] As any possible implementation manner described above, further provides an implementation manner, the gradient revolution body part is prepared by a revolution body forming device, and the revolution body forming device includes:

[0028] A circular ring forming cylinder is integrally arranged with the circular rotating platform, the circular ring forming cylinder can rotate around its center and can vertically ascend and descend.

[0029] A gradient powder supply and powder laying unit is used to form a powder layer that is set to be gradient in the radial direction and uniform in the circumferential direction in the circular ring forming cylinder.

[0030] A forming unit is used to laser consolidate a set area of the laid powder layer.

[0031] A control unit is used to control the rotation of the circular ring forming cylinder, the vertical ascending and descending of the circular ring forming cylinder, and the laser consolidation of the forming unit.

[0032] As any possible implementation manner described above, further provides an implementation manner, one end of the gradient powder supply and powder laying unit is arranged at the center of the circular ring forming cylinder, and the other end extends to the outer ring of the circular ring forming cylinder.

[0033] The gradient powder supply and powder laying unit comprises a powder reservoir from top to bottom, a quantitative powder feeder, a grid hopper, a powder mixer and a powder laying device; the powder laying direction of the powder laying device is the circumferential direction of the circular ring forming cylinder, the moving direction of the powder reservoir is the radial direction of the circular ring forming cylinder, and the vertical direction is the Z direction, wherein the circumferential direction of the circular ring forming cylinder, the radial direction of the circular ring forming cylinder and the Z direction are perpendicular to each other;

[0034] The number of the powder reservoirs is two or more, and the powder reservoirs are arranged side by side in the radial direction perpendicular to the circular ring forming cylinder; each of the powder reservoirs is provided below with the quantitative powder feeder for controlling the powder supply amount; and the powder reservoirs can move in the radial direction of the circular ring forming cylinder.

[0035] The grid hopper is in the shape of a funnel and forms a grid in the radial direction of the circular ring forming cylinder; the grid hopper receives two or more kinds of powder from the quantitative powder feeder and forms a set gradient of each kind of powder in the radial direction of the circular ring forming cylinder.

[0036] The powder mixer is arranged at the lower end of the grid hopper and is used for uniformly mixing the powder from the grid hopper in the circumferential direction of the circular ring forming cylinder while keeping the set gradient in the radial direction of the circular ring forming cylinder.

[0037] The powder laying device is arranged below the powder mixer and is used for receiving the powder from the powder mixer which has been uniformly mixed in the circumferential direction of the circular ring forming cylinder and kept the set gradient in the radial direction of the circular ring forming cylinder; and the powder laying device lays powder in the circumferential direction of the circular ring forming cylinder.

[0038] According to any possible implementation manner described above, further provided is an implementation manner, wherein the gradient powder supply and powder laying unit further comprises a powder reservoir driving subunit, and the powder reservoir driving subunit comprises a powder reservoir fixing frame, a sliding guide rail and a driving motor.

[0039] The sliding guide rail is arranged in the radial direction of the circular ring forming cylinder, two or more powder reservoirs are fixedly arranged side by side on the powder reservoir fixing frame, the powder reservoir fixing frame is slidingly connected to the sliding guide rail, and the driving motor drives the powder reservoir fixing frame to move in the radial direction of the circular ring forming cylinder along the sliding guide rail.

[0040] The present application has the advantages that the present application can realize the dense scanning of the current powder layer during the movement of the circular ring forming platform, the laser center only needs to scan on a line, and the coupling with the laser process parameters is realized by adjusting the rotating speed of the circular ring platform; the present application can be particularly applied to the preparation of gradient revolution body parts and has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The figure shows the technical principle diagram of the present application.

[0042] Figure 2 Figure 1 shows a schematic diagram of a laser scanning area in an embodiment.

[0043] Figure 3 Figure 2 shows a schematic diagram of a structure of a rotary body forming device in an embodiment.

[0044] Figure 4 Figure 3 shows a schematic diagram of a structure of a gradient powder supply and powder laying unit in an embodiment.

[0045] Figure 5 Figure 4 shows a schematic diagram of a side view of a gradient powder supply and powder laying unit in an embodiment.

[0046] Figure 6 Figure 5 shows a schematic diagram of a front view of a gradient powder supply and powder laying unit in an embodiment.

[0047] In the figure: 1 - gradient powder supply and powder laying unit; 2 - circular ring forming cylinder (including inner ring and outer ring); 3 - (gradient) powder layer; 11 - powder reservoir fixing frame; 12 - powder reservoir; 13 - quantitative powder feeder; 14 - grid hopper; 15 - powder mixing roller; 16 - powder laying device; 17 - sliding guide rail; 18 - driving motor; 19 - workbench. The powder reservoir can be set according to actual needs, two or more powder reservoirs can be set, each powder reservoir is placed with different alloy powder, which is commonly used 3D printing powder. DETAILED DESCRIPTION

[0048] The specific embodiments of the present application will be described in detail below with reference to specific drawings. It should be noted that the technical features described in the following embodiments should not be considered in isolation, and they can be combined with each other to achieve better technical effects.

[0049] An embodiment of the present application is a laser continuous scanning method for a rotating platform laser powder bed additive manufacturing, the rotating platform is a circular ring platform, the method comprises:

[0050] S1, the circular ring platform is divided into a plurality of fan-shaped micro-zones with the same size; the width of each fan-shaped micro-zone is D1 at the inner ring of the circular ring platform and D2 at the outer ring of the circular ring platform;

[0051] S2, the scanning path of the laser is a straight line reciprocating, scanning from the outer ring to the inner ring of the circular ring platform; the laser does not emit light (empty jump) when returning from the inner ring to the outer ring; the spot diameter of the laser is R2≥D2 at the outer ring and R1≥D1 at the inner ring; the spot diameter of the laser continuously changes from large to small during the scanning process, and the laser spot scans one fan-shaped micro-zone each time;

[0052] S3, the circular platform rotates at an angular velocity w, while the laser continuously scans the powder layer on the circular platform according to the path set in step S2 at a linear velocity v.

[0053] For the convenience of description, the inner diameter of the circular platform is r1, the outer diameter is r2, and the rotating speed of the platform is w. The laser is a circular spot, and the minimum diameter of the spot is R1 (at the inner ring) and the maximum diameter of the spot is R2 (at the outer ring).

[0054] The laser process parameters include the scanning speed v and the laser line overlap rate (laser line spacing).

[0055] The circular platform is divided into a plurality of fan-shaped micro-zones S of the same size, and the size of the fan-shaped micro-zone is associated with the diameter of the spot. The spot can cover the fan-shaped micro-zone at the outer ring and the inner ring, that is, the diameter of the laser spot at the outer ring is R2≥D2, and the diameter of the laser spot at the inner ring is R1≥D1; D2 and D1 are the width of the fan-shaped micro-zone at the outer ring and the inner ring, respectively. The size of the fan-shaped micro-zone can be appropriately adjusted according to the process.

[0056] In a specific embodiment, the position of a certain fan-shaped micro-zone s1 is determined, the adjacent fan-shaped micro-zone in the rotating direction of the circular platform is s2, and the adjacent fan-shaped micro-zone in the reverse rotating direction of the circular platform is s3. The center of the laser moves only on a line segment, that is, the connecting segment of the midpoint of the outer ring of the fan-shaped micro-zone s1 to the midpoint of the inner ring of the fan-shaped micro-zone s2. The outer ring width of the fan-shaped micro-zone is the outer ring diameter R2 of the spot, and the inner ring width of the fan-shaped micro-zone is the inner ring diameter R1 of the spot. In the process of scanning from the outer ring to the inner ring of the fan-shaped micro-zone, the diameter of the laser spot gradually changes from large to small, and the ratio of the spot diameter R at any position to R2 is equal to the ratio of the current position to the outer ring radius r2.

[0057] The laser moves back and forth along the connecting line between the starting point and the ending point. The maximum distance of the laser movement is that the laser moves from the midpoint of the outer ring of the fan-shaped micro-zone s1 to the midpoint of the inner ring of the fan-shaped micro-zone s2 and then moves to the midpoint of the outer ring of the fan-shaped micro-zone s1. The actual scanning length of the laser is related to the position and the model of the part, and the laser does not emit light at other positions and makes an empty jump movement. The total time of each reciprocating motion is t. When the forming platform rotates, the powder in the s3 fan-shaped micro-zone moves to the s1 fan-shaped micro-zone after time t, and the powder in the s1 fan-shaped micro-zone moves to the s2 fan-shaped micro-zone after time t.

[0058] The relationship between the above parameters is: first, the laser scanning speed and the overlap rate of two adjacent laser lines are determined according to the material, the maximum spot diameter R2 and the minimum spot diameter R1 used are further determined, and then the size of the fan-shaped micro area is determined; the distance X between the midpoint of the outer arc of the s1 fan-shaped micro area and the midpoint of the inner arc of the s2 fan-shaped micro area is determined according to the laser scanning speed V; after the laser scans from the starting point to the ending point, it needs to return to the starting point, and the empty jump speed is much larger than the scanning speed, so a time allowance is set at the termination point, that is, the laser line jumps to the starting point in advance before reaching the termination point; the unit time t is the time required for the above reciprocating process; the angle θ between the two fan-shaped micro areas is determined according to the overlap rate OR; and the rotating speed w of the platform is determined by the angle θ between the fan-shaped micro areas and the unit time t.

[0059] In one specific embodiment, the determination method of the laser scanning line speed v, the rotating angular speed w of the circular ring platform and the size of the fan-shaped micro area (measured by the included angle of the midlines of adjacent fan-shaped micro areas) is as follows:

[0060] S3.1 The laser scanning line speed v and the laser overlap rate H are determined according to the powder layer material and the powder layer thickness, and the range is (0-100%), which represents the angle of overlap of two adjacent sectors; then the included angle θ between the center lines of the two fan-shaped micro areas can be obtained according to the relationship of formula (1):

[0061] θ=2(1-H)arcsin(R1 / r1) (1);

[0062] S3.2 The scanning distance X from the starting point to the ending point of the laser scanning is determined:

[0063]

[0064] S3.3 The time t required for one reciprocating laser scanning is determined:

[0065] t=X / v (3);

[0066] S3.4 The rotating angular speed w of the circular ring platform is determined:

[0067] w=(θ*X) / v (4)。

[0068] In one specific embodiment, when the prepared part has a specific shape, first, the part is sliced and analyzed to determine the to-be-scanned melting area of each powder layer; then during the scanning of each powder layer, the laser only emits light in the to-be-scanned melting area, and does not emit light in the non-to-be-scanned melting area, thereby completing the laser scanning of the powder layer.

[0069] The above method of the application can be used for laser scanning of a powder or a plurality of powders on a circular ring platform.

[0070] This invention relates to an application of the aforementioned laser continuous scanning method for laser powder bed additive manufacturing on a rotating platform in the preparation of gradient rotating body parts. The gradient rotating body parts include two or more types of powders. The gradient rotating body parts are formed on an annular rotating platform. The proportions of each powder in the gradient rotating body parts are distributed in a predetermined gradient in the radial direction and uniformly in the circumferential direction of the annulus where the gradient rotating body is located.

[0071] In one specific embodiment, the gradient rotary body part is prepared by a rotary body forming apparatus, the rotary body forming apparatus comprising:

[0072] The annular forming cylinder 2 is integrally formed with the annular rotating platform. The annular forming cylinder 2 can rotate around its center and can be vertically raised and lowered.

[0073] The gradient powder supply and spreading unit 1 is used to form a powder layer with a set radial gradient and a uniform circumferential distribution in the annular forming cylinder 2.

[0074] The forming unit is used to laser fuse a designated area of ​​the pre-laid powder layer;

[0075] The control unit is used to control the rotation of the annular forming cylinder 2, the vertical lifting and lowering of the annular forming cylinder 2, and the laser welding of the forming unit.

[0076] In one specific embodiment, such as Figure 3 As shown, one end of the gradient powder supply and spreading unit 1 is located at the center of the annular forming cylinder 2, and the other end extends to the outer ring of the annular forming cylinder 2.

[0077] Figures 4-6 These are the top view, side view, and front view of the gradient powder supply and spreading unit, respectively.

[0078] The gradient powder supply and spreading unit 1 includes, from top to bottom, a powder storage tank 11, a quantitative powder feeder 13, a grid material trough 14, a powder mixer (mixing roller 15), and a powder spreader 16; the powder spreading direction of the powder spreader 16 is circumferential to the annular forming cylinder 2. Figure 3 The powder storage device 12 moves in the radial direction of the annular forming cylinder 2 (in the direction of the center w). Figure 3 The circumferential direction of the annular forming cylinder 2, the radial direction of the annular forming cylinder 2, and the Z-direction are perpendicular to each other.

[0079] The number of powder storage devices 12 is two or more, and the powder storage devices 12 are arranged side by side along the radial direction perpendicular to the annular forming cylinder 2. Each powder storage device 12 is provided with a quantitative powder feeder 13 for controlling the powder supply below it; the powder storage device 12 can move radially along the annular forming cylinder 2.

[0080] The grid hopper 14 is funnel-shaped and forms a grid in the radial direction of the ring forming die 2; the grid hopper 14 receives two or more powders from the dosing feeder 13 and forms a set gradient of each powder in the radial direction of the ring forming die 2;

[0081] The powder mixer (powder mixing roller 15) is arranged at the lower end of the grid hopper 14 and is used to uniformly mix the powders from the grid hopper 14 in the circumferential direction of the ring forming die 2 while maintaining the set gradient in the radial direction of the ring forming die 2;

[0082] The powder laying device 16 is arranged below the powder mixer (powder mixing roller 15) and is used to receive the powders from the powder mixer 15 that have been uniformly mixed in the circumferential direction of the ring forming die 2 and maintained the set gradient in the radial direction of the ring forming die 2; the powder laying device 16 lays the powders along the circumferential direction of the ring forming die 2.

[0083] The gradient powder feeding and laying unit 1 further comprises a powder reservoir driving subunit, which comprises a powder reservoir fixing frame 11, a sliding guide rail 17 and a driving motor 18;

[0084] The sliding guide rail 17 is arranged in the radial direction of the ring forming die 2, and two or more powder reservoirs 12 are fixedly installed side by side on the powder reservoir fixing frame 11, the powder reservoir fixing frame 11 is slidingly connected to the sliding guide rail 17, and the driving motor 18 drives the powder reservoir fixing frame 11 to move in the radial direction of the ring forming die 2 along the sliding guide rail 17.

[0085] In one specific embodiment, a plurality of powder reservoirs 12 are fixed to the powder reservoir fixing frame 11, and the bottom of the powder reservoir 12 is the dosing feeder 13; the powders can flow into the grid hopper 14 through the dosing feeder 13, and the amount of powder is ensured by the number of times the dosing feeder 13 is opened.

[0086] The grid hopper 14 is located below the powder storage 12 and the sliding guide 17 to receive the powder supplied by the dosing feeder 13. The grid hopper 14 is funnel-shaped as a whole from top to bottom, and the top is rectangular with the same length as the sliding guide 17 in the OR direction. The length perpendicular to the OR direction can be set according to the actual number of powder storages 12, that is, longer than the length of the multiple powder storages 12 arranged side by side perpendicular to the OR direction, to ensure that the powder flowing out of the dosing feeder 13 can flow into the grid hopper 14. The grid hopper 14 is divided into equal parts along the OR direction. When the powder storage fixing frame 11 moves along the sliding guide 17, the starting position of the movement is the first grid, and the step length of each movement is one grid distance. When stopping at each grid, each powder storage 12 supplies different amounts of powder to the current grid through the dosing feeder 13 according to the respective settings, and then the driving motor 18 controls the movement of the powder storage 12 to the next grid.

[0087] The amount of powder in each grid is determined by the powder layer thickness, the current position gradient ratio, and the distance between the current position and the center.

[0088] In a specific embodiment, the size of the dosing feeder 13 corresponds to the size of the grid hopper 14. The length of the grid hopper 14 perpendicular to the OR direction is N mm. The purpose of the grid hopper 14 is to divide the entire powder layer into multiple areas for separate powder supply along the OR direction, and the areas are set as p1, p2, p3, ··· pn, with each grid width or area width being 1 mm. According to the gradient change ratio of the powder layer along the OR direction, the number of times each dosing feeder 13 is turned on in each grid is determined, that is, the proportion and total amount of the composition at the corresponding position. Figure 5 For the top view of the grid hopper 14, the width of each area in the grid hopper 14 determines the accuracy of the gradient ratio change.

[0089] In a specific embodiment, the powder enters the powder mixing drum 15 after passing through the grid hopper 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 direction while maintaining the preset gradient in the OR direction.

[0090] In a specific embodiment, the powder is mixed by the powder mixing drum 15 and then enters the powder spreader 16. The powder spreader 16 moves in a circular motion around the center O and lays the gradient powder on the powder bed of the forming cylinder. Before laying the next layer of powder, the circular ring forming cylinder 2 is lowered by a certain layer thickness distance.

[0091] The gradient change ratio of each layer of powder in the radial direction can be set individually, thereby realizing a gradient with an arbitrary direction ratio in the printing part (radial-Z) plane.

[0092] The method for spreading powder on the circular ring forming cylinder 2 using the device as described above specifically includes:

[0093] X1, two or more powder reservoirs 12 are fixed side by side on the powder reservoir fixing frame 11, and different powder reservoirs 12 respectively contain different kinds of powder;

[0094] X2, the gradient powder supply and powder laying unit 1 is in an initial position; the initial position of the powder reservoir 12 is the first grid of the grid hopper 14, and the powder reservoir 12 moves radially by one grid interval each time; each powder reservoir 12 supplies different amounts of powder to the current grid of the grid hopper 14 according to the respective setting through the quantitative powder feeder 13, and then controls the powder reservoir 12 to move to the next grid, and repeats the powder supply action until all the grids are walked, that is, the gradient change of the powder ratio along the radial direction of the circular forming cylinder 2 is realized;

[0095] X3, the powder mixer (powder mixing roller 15) receives the powder from the grid hopper 14, and uniformly mixes the powder in the circumferential direction of the circular forming cylinder 2 while keeping the set gradient in the radial direction of the circular forming cylinder 2;

[0096] X4, the powder laying device 16 receives the powder from the powder mixer 15, and rotates around the center of the circular forming cylinder 2 to lay the gradient powder on the circular forming cylinder 2; the gradient change of the powder ratio along the radial direction of the circular forming cylinder 2 and the uniform distribution of the powder along the circumferential direction of the circular forming cylinder 2 are realized;

[0097] X5, the laser scans the set area of the powder layer of the forming cylinder to complete the current layer of the part; or the binder sprays the set area of the powder layer of the forming cylinder to complete the current layer of the part;

[0098] X6, the steps X2-X5 are repeated until all the layers of the part are printed, and the continuous and controllable gradient distribution of the part in the (radial-Z) dimension is realized by controlling the composition ratio of each layer of powder in the radial direction of the circular forming cylinder 2 and the composition ratio of different layers of powder in the Z direction.

[0099] The present application realizes the dense scanning of the current powder layer during the movement of the circular platform, and the laser center only needs to scan on a line, and the coupling with the laser process parameters is realized by adjusting the rotating speed of the circular platform.

[0100] Although several embodiments of the present application have been given in the present text, those skilled in the art should understand that the embodiments in the present text can be changed without departing from the spirit of the present application. The above embodiments are only exemplary, and the embodiments in the present text should not be used as the limitation of the scope of the rights of the present application.

Claims

1. A method of laser continuous scanning for a rotating platform laser powder bed additive manufacturing, the rotating platform being a circular ring platform, characterized in that, The method comprises: S1, the circular ring platform is divided into a plurality of fan-shaped micro-zones with the same size; each fan-shaped micro-zone has a width of D1 at the inner ring of the circular ring platform and a width of D2 at the outer ring of the circular ring platform; S2, the scanning path of the laser is a straight reciprocating line, scanning from the outer ring to the inner ring of the circular ring platform, and the laser does not emit light when returning from the inner ring to the outer ring; the spot diameter of the laser at the outer ring is R2≥D2, and the spot diameter of the laser at the inner ring is R1≥D1; the spot diameter of the laser continuously changes from large to small during scanning, and the laser spot scans one fan-shaped micro-zone in each reciprocating scan; S3, the circular ring platform rotates at an angular velocity w, and the laser continuously scans the powder layer on the circular ring platform at a linear velocity v according to the path set in step S2; In step S2, the method for determining the scanning path of the laser is as follows: In the three adjacent fan-shaped micro-zones, the starting point of laser scanning is the midpoint of the outer ring of the middle fan-shaped micro-zone, and the end point of laser scanning is the midpoint of the inner ring of the adjacent fan-shaped micro-zone in the rotation direction of the circular ring platform; the laser reciprocates along the line connecting the starting point and the end point; The inner ring of the circular ring platform has a radius of r1, and the outer ring has a radius of r2; in step S2, the ratio of the spot diameter R of the laser to R2 at any scanning position is equal to the ratio of the current position radius to the outer ring radius r2; In step S3, the linear scanning velocity v of the laser, the angular velocity w of the circular ring platform, and the size of the fan-shaped micro-zone are determined as follows: S3.1, the linear scanning velocity v of the laser and the laser overlap rate H are determined according to the powder layer material and the powder layer thickness, and the included angle θ between the center lines of two fan-shaped micro-zones is: θ=2(1-H)arcsin(R1 / r1); S3.2, the scanning distance X from the starting point to the end point of laser scanning is determined: S3.3, the time t required for one reciprocating scan of laser scanning is determined: t=X / v; S3.4, the angular velocity w of the circular ring platform is determined: w=(θ*v) / X.

2. The method for laser continuous scanning for rotary platform laser powder bed additive manufacturing of claim 1, wherein, The additive is one or several kinds of metal powder.

3. The method for laser continuous scanning for rotary platform laser powder bed additive manufacturing of claim 1, wherein, First, the part is sliced and analyzed to determine the to-be-scanned melting area of each powder layer; then during scanning of each powder layer, the laser only emits light in the to-be-scanned melting area, and does not emit light in the non-to-be-scanned melting area, thereby completing laser scanning of the powder layer.

4. Use of a laser continuous scanning method for the additive manufacturing of rotating platform laser powder bed as claimed in any one of claims 1-3 in the production of a gradient revolved body part, characterized in that, The gradient rotary body part comprises two or more than two kinds of powder, and the gradient rotary body part is formed on a circular ring rotating platform; the proportion of each powder in the gradient rotary body part is set to have a gradient in the radial direction of the circular ring and to have a uniform distribution in the circumferential direction.

5. The use according to claim 4, wherein the compound is ###0002### The gradient rotary body part is prepared by a rotary body forming device, and the rotary body forming device comprises: a circular ring forming cylinder which is integrally arranged with the circular ring rotating platform, can rotate around the center of the circular ring, and can vertically ascend and descend; a gradient powder supply and powder laying unit which is used to form a powder layer with a set gradient in the radial direction and a uniform distribution in the circumferential direction in the circular ring forming cylinder; a forming unit which is used to laser consolidate a set area of the laid powder layer. A control unit is configured to control rotation of the circular forming cylinder, vertical lifting of the circular forming cylinder, and laser cladding of the forming unit.

6. The use according to claim 5, wherein the compound is ###0002### One end of the gradient powder supply and distribution unit is arranged at the center of the circular forming cylinder, and the other end extends to the outer ring of the circular forming cylinder. The gradient powder supply and distribution unit comprises, from top to bottom, a powder storage device, a quantitative powder feeder, a grid hopper, a powder mixer, and a powder distributor. The powder distribution direction of the powder distributor is the circumferential direction of the circular forming cylinder, the moving direction of the powder storage device is the radial direction of the circular forming cylinder, and the vertical direction is the Z direction, wherein the circumferential direction of the circular forming cylinder, the radial direction of the circular 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 the radial direction of the circular forming cylinder. Each of the powder storage devices is provided below with the quantitative powder feeder for controlling the powder supply amount. The powder storage devices are movable in the radial direction of the circular forming cylinder. The grid hopper is in the shape of a funnel and forms a grid in the radial direction of the circular forming cylinder. The grid hopper receives two or more kinds of powder from the quantitative powder feeder and forms a set gradient of each kind of powder in the radial direction of the circular forming cylinder. The powder mixer is arranged at the lower end of the grid hopper and is configured to uniformly mix the powder from the grid hopper in the circumferential direction of the circular forming cylinder while maintaining the set gradient in the radial direction of the circular forming cylinder. The powder distributor is arranged below the powder mixer and is configured to receive the powder from the powder mixer, which has been uniformly mixed in the circumferential direction of the circular forming cylinder and maintained the set gradient in the radial direction of the circular forming cylinder. The powder distributor distributes the powder in the circumferential direction of the circular forming cylinder.

7. Use according to claim 6, wherein The gradient powder supply and distribution unit further comprises a powder storage device driving subunit, which comprises a powder storage device fixing frame, a sliding guide rail, and a driving motor. The sliding guide rail is arranged in the radial direction of the circular forming cylinder. Two or more powder storage devices are fixedly installed side by side on the powder storage device fixing frame, which is slidingly connected to the sliding guide rail. The driving motor drives the powder storage device fixing frame to move in the radial direction of the circular forming cylinder along the sliding guide rail.

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