Additive manufacturing method, manufacturing equipment and forming platform

Abstract

The invention relates to the technical field of additive manufacturing, in particular to an additive manufacturing method, manufacturing equipment and a forming platform, and the additive manufacturing method comprises the steps that a base material with a forming face and a functional part with an entity boundary are configured; the top surfaces of the base material and the functional part are initially reset and have the same height as the powder spreading surface; and a printing task is executed, and in the printing process, at least part of the top face of the functional part protrudes out of the top face of the base material and is contained in at least part of the area outside the main body structure of the printing workpiece. In the 3D powder laying printing process of additive manufacturing, the functional part is arranged in at least part of the area, except the printing workpiece main body structure, in the forming bin, and the functional part can achieve the effects of filling, supporting and being combined with the printing workpiece main body structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing technology, in particular to an additive manufacturing method, manufacturing equipment and forming platform. BACKGROUND

[0002] In the field of additive manufacturing (3D printing), 3D powder laying printing is an additive manufacturing process based on powder bed melting technology, as shown in FIG. 1, the core principle of which is to lay the powder in the powder bin 3 on the forming platform 2 (substrate) in the forming bin 1 layer by layer through the powder laying part 4, and to selectively melt the powder by emitting high-energy beam 51 (such as laser, electron beam) by the high-energy beam generating device 5, and finally to stack a three-dimensional part. Figure 1

[0003] However, in the process of printing non-solid workpieces or batch processing, limited by the technical principle, the powder laying system needs to uniformly lay powder in the entire forming area, including the body part of the workpiece and the remaining area except the solid part. Combined with FIG. 2 and FIG. 3, most of the space in the forming bin except the main body of the workpiece and the necessary support structure needs to be filled layer by layer with powder to ensure the uniformity of powder laying and the stability of forming. This "global powder filling" mode will cause a large amount of powder to exist only as a "space filler" when the volume of the workpiece is small, the structure is loose, or the specification of the forming bin does not match the size of the workpiece. Although part of the un-melted powder can be recycled, the problems of inevitable particle oxidation, impurity mixing, and particle size distribution change in the recycling process will cause about 10%-30% of the powder to be scrapped due to performance degradation, resulting in significant waste of resources and cost pressure. Figure 1 Figure 2 The present application relates to the field of additive manufacturing technology, in particular to an additive manufacturing method, manufacturing equipment and forming platform. SUMMARY

[0004] The purpose of the present application is to provide an additive manufacturing method, manufacturing equipment and forming platform to solve the problem of serious waste of metal powder in the process of printing non-solid workpieces or batch processing in the prior art.

[0005] The technical solution of the present application is: an additive manufacturing method, comprising: configuring a base material with a forming surface, and a functional part with a solid boundary; the top surface of the base material and the functional part is initially reset and has the same height as the powder laying surface; performing a printing task, and in the printing process, at least part of the top surface of the functional part protrudes from the top surface of the base material and is accommodated in at least part of the area outside the main structure of the printed workpiece.

[0006] Preferably, in any projection plane parallel to the forming surface, when the vertical projection of the functional part overlaps the vertical projection of the main structure of the printed workpiece, the corresponding functional part is provided with a lifting drive.

[0007] ​​Preferably, the functional part is configured as at least one non-deformable structure, and the functional part driven by the lifting drive is driven by an independent lifting drive, and then the lifting displacement occurs.

[0008] Preferably, in the printing process, when the projection of the powder-printing area and the functional part in the direction perpendicular to the powdering direction overlaps, the functional part moves downward in advance. After the functional part starts to move downward, before performing powdering each time, the functional part moves downward with the substrate by a distance equal to the preset single-layer printing thickness, and each time the downward movement is defined as one time unit.

[0009] Preferably, the functional part is used to perform the filling function, and when the projection of the powder-printing area and the functional part in the direction perpendicular to the powdering direction overlaps, the functional part moves downward at any time in advance.

[0010] Preferably, the functional part is used to perform the support function, and when the projection of the powder-printing area and the functional part in the direction perpendicular to the powdering direction overlaps, the functional part moves downward one time unit in advance.

[0011] Preferably, the functional part is configured as a part of the printing workpiece main structure, and when the projection of the powder-printing area and the functional part in the direction perpendicular to the powdering direction overlaps, the functional part moves downward one time unit in advance.

[0012] Preferably, when the functional part moves downward one time unit in advance, the functional part is in direct contact with the printing workpiece, the functional part at least at the top thereof adopts a material that does not form metallurgical bonding with the printing workpiece main structure, and the functional part also synchronously supports the printing workpiece main structure. When the functional part moves downward two or more time units in advance, there is a gap between the functional part and the printing workpiece and the gap is filled with powder, and the functional part adopts a material with a melting point not lower than that of the powder.

[0013] Preferably, the functional part is configured as a deformable structure and is driven by an independent medium filling device to deform.

[0014] Preferably, the functional part and the substrate are driven by independent lifting drives, and after the substrate moves downward n times, the functional part deforms once.

[0015] Preferably, the lifting control method of the functional part is as follows: The functional part and the substrate move together and move downward n times. The functional part is driven to move downward relative to the base material alone to make the powder accumulated above the functional part slide down; The functional part moves upward to reset, and the medium filling device is opened to make the at least partial upper end surface of the functional part be at the same height as the powder laying surface. The above-mentioned actions are repeated.

[0016] Preferably, the functional part and the base material are driven by the same lifting driving part, and the functional part is lifted and followed; after the base material moves downward n times, the functional part deforms once.

[0017] The application further discloses an additive manufacturing equipment for executing the additive manufacturing method, which comprises: A forming bin, wherein a forming platform is arranged, the forming platform comprises a base material with a forming surface and a functional part with a solid boundary; A powder bin, which is filled with powder to be laid and is driven to make the powder overflow or separate from the powder bin; A powder laying part, which reciprocates in a powder laying surface to lay the powder in the powder bin on the forming bin; A high-energy beam generating device, which is used to emit laser or electron beam and irradiate the powder above the forming platform to selectively melt the powder.

[0018] Preferably, the functional part is configured as at least one non-deformation structure, the functional part with the lifting driving part is driven by independent lifting driving parts respectively, and the top surfaces of the base material and the functional part form a complete plane in the initial reset state.

[0019] Preferably, the base material and the functional part are configured as coaxial ring structures which are nested in sequence, and the corresponding printed workpiece main structure is configured as a single hollow structure with a preset wall thickness.

[0020] Preferably, the functional part is configured as a plurality of column structures penetrating the base material, and the corresponding printed workpiece main structure is configured as a plurality of solid structures or hollow structures processed in batches.

[0021] Preferably, the base material and the functional part are combined by a plurality of movable parts driven independently, and the movable part covered by the corresponding printing area at the bottom of the printed workpiece main structure is configured as the base material, and the other movable parts are configured as the functional part.

[0022] Preferably, the functional part is configured as a deformation structure and is placed in a containing space in the base material, and the functional part is connected with a medium filling device.

[0023] Preferably, the functional part is fixed in the base material and is driven to move vertically by the lifting driving part.

[0024] Preferably, the functional part is movably fitted in the base material, and the functional part and the base material are respectively provided with independent lifting driving parts.

[0025] Compared with the prior art, the present application has the following advantages: (1) In the 3D powder laying printing process of additive manufacturing, by configuring the functional part in at least part of the area outside the main structure of the printed workpiece in the forming bin, the functional part can play the role of filling, supporting and combining with the main structure of the printed workpiece. When filling, the amount of powder is reduced in the form of physically occupying space, which essentially realizes the precise use of the "invalid space" of the forming bin, and also reduces the recycling cost and optimizes the whole process efficiency. When supporting, for large-span overhanging structures, the upper layer of molten metal lacks sufficient support and is easy to fall due to gravity when printing layer by layer; thin-walled parts or deep cavity structures are easy to produce cracks along the wall thickness direction due to uneven shrinkage caused by large temperature difference between inside and outside when cooling; at this time, the functional part not only solves the material waste problem of traditional support structure, but also strengthens the stability of the forming process. When combining with the main structure of the printed workpiece, for some products that need to be printed in batches, the combination of products printed in batches is realized by pre-embedding.

[0026] (2) The functional part can be either a non-deformation structure made of rigid material or a deformation structure used for filling medium; the former can be matched with the printed workpiece efficiently, and the form does not change during printing, which can fully play the role of structural stability and supporting performance, high reusability and controllable size precision; the latter has dynamic form changing ability, and due to its characteristics of middle bulging and four sides collapsing in the expanded state, it is more suitable for large workpiece printing scenes. BRIEF DESCRIPTION OF DRAWINGS

[0027] The present application will be further described below in combination with the drawings and examples: Figure 1 It is a structural schematic diagram of the additive manufacturing equipment in the prior art; Figure 2 It is the filling state of the powder after printing on the traditional substrate in the prior art; Figure 3 It is a structural schematic diagram of the additive manufacturing equipment provided in an exemplary scheme of the present application; Figure 4 It is a distribution diagram of the forming platform and the printed workpiece when the functional part is constructed as multiple non-deformation structures and is respectively driven by independent lifting driving parts in an exemplary scheme of the present application; Figure 5 It is a top view of the forming platform adapting to different forming bin contour shapes in an exemplary scheme of the present application; Figure 6A state diagram of the forming platform corresponding to the additive manufacturing method provided in an exemplary embodiment of the present application; Figure 7 A state diagram of the substrate and the functional member when the projection of the printing area and the functional member in the direction perpendicular to the powder laying direction does not overlap in an exemplary embodiment of the present application; Figure 8 A state diagram of the functional member undergoing downward movement at time t when the projection of the printing area and the functional member in the direction perpendicular to the powder laying direction overlaps in an exemplary embodiment of the present application; Figure 9 A state diagram of the functional member undergoing downward movement before time t when the projection of the printing area and the functional member in the direction perpendicular to the powder laying direction overlaps in an exemplary embodiment of the present application; Figure 10 A distribution diagram of the functional member and the substrate in a forming platform composed of multiple movable members in another exemplary embodiment of the present application; Figure 11 A distribution diagram of the functional member and the substrate in a forming platform composed of multiple movable members in another exemplary embodiment of the present application; Figure 10 Figure 12 A principle diagram in which the functional member is configured as a plurality of column structures penetrating the substrate, and the workpiece to be printed is configured as a plurality of solid structures processed in batches in other exemplary embodiments of the present application; Figure 13 A top view of the substrate and the functional member in other exemplary embodiments of the present application; Figure 14 A principle diagram in which the functional member is configured as a plurality of column structures penetrating the substrate, and the workpiece to be printed is configured as a plurality of hollow structures processed in batches, and the functional member is fixedly arranged in other exemplary embodiments of the present application; Figure 15 A principle diagram in which the functional member is configured as a plurality of column structures penetrating the substrate, and the workpiece to be printed is configured as a plurality of hollow structures processed in batches, and the functional member is capable of undergoing lifting displacement in other exemplary embodiments of the present application; Figure 16 A principle diagram of printing an overhanging structure in other exemplary embodiments of the present application; Figure 17 A principle diagram in which the functional member is configured as a deformed structure, the functional member and the substrate are synchronously driven, and the functional member is driven by an independent medium filling device in still another exemplary embodiment of the present application; Figure 18 A principle diagram of the functional member after gradual deformation in still another exemplary embodiment of the present application; ​Figure 19 This is a schematic diagram of a further exemplary embodiment of the present invention in which the functional component is constructed as a deformable structure, the functional component and the substrate are driven independently, and the functional component is driven by an independent medium filling device. Figure 20 This is a schematic diagram illustrating the principle of a functional component descending relative to the substrate and causing powder to slide off in another exemplary embodiment of the present invention.

[0028] Among them: 1. Forming chamber, 2. Forming platform, 21. Substrate, 22. Functional component, 3. Powder silo, 4. Powder spreading component, 5. High energy beam generator, 51. High energy beam. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments: To facilitate understanding, the application scenario of this application will first be explained. In the process of additive manufacturing 3D metal powder-layout printing (such as SLM, LPBF, etc.), powder is a core raw material, and its cost often accounts for a significant proportion of the entire production chain—especially high-performance powders such as titanium alloys, high-temperature alloys, and precious metals. Figure 1 As shown, after printing, most of the space in the forming chamber, except for the workpiece body and necessary support structures, needs to be filled with powder layer by layer to ensure uniform powder distribution and forming stability. A large amount of filled powder can become contaminated, for example, through oxidation (e.g., aluminum, titanium alloys), impurity contamination (e.g., mixing with other metals or non-metals), thermal damage, or changes in particle size distribution. This powder cannot be directly reused and generally requires treatment for reuse or direct disposal. This application aims to solve the problem of "full-area powder filling" in the forming chamber.

[0030] like Figure 3 As shown, the additive manufacturing equipment mainly includes a forming chamber 1, a powder chamber 3, a powder-laying part 4, and a high-energy beam generator 5. It follows the process logic of "layer-by-layer powder laying - laser melting - layer stacking" and simultaneously meets the requirements of high precision, high stability, and inert environmental protection.

[0031] The forming chamber 1 is a closed working space for the printing process, providing a stable physical environment for part forming. It is made of high-strength metal and has high airtightness, which can isolate the outside air and prevent the metal powder from oxidizing, burning or exploding, especially for easily oxidized materials such as titanium alloys and aluminum alloys.

[0032] Powder hopper 3 contains the powder to be laid, and can generally adopt two powder supply methods: "top supply" and "bottom supply"; for example Figure 3 As shown, bottom powder supply means that both the powder silo 3 and the forming silo 1 are located at the bottom of the equipment, and the powder is pushed up and overflowed by the rising powder supply cylinder; top powder supply means that the powder silo 3 is located above the forming silo 1, usually at the top or side of the forming silo 1, and the powder is transported to the forming area by gravity powder falling, spiral powder feeding or vacuum powder suction.

[0033] The powder spreading component 4 uses a powder spreading roller or scraper to reciprocate within the powder spreading surface, spreading the powder in the powder hopper 3 evenly above the forming hopper 1 to form a powder layer of uniform thickness (usually 20-100μm), which is the core to ensure the interlayer accuracy.

[0034] The high-energy beam generator 5 is used to emit laser or electron beams. By focusing the high-energy beam 51 and irradiating the powder above the forming platform, the powder is selectively melted to achieve intralayer metallurgical bonding.

[0035] In traditional structures, such as Figure 1 As shown, the molding platform 2 within the molding chamber 1 is a flat substrate, serving as the growth base for the parts. Its material matches the printing material, and its surface is precision ground to ensure good contact with the first layer of powder, gradually descending during the layer-by-layer printing process. It is precisely because of this traditional flat substrate structure that the phenomenon of "full-area powder filling" occurs. Therefore, in this application, the molding platform 2 within the molding chamber 1 includes a substrate 21 with a molding surface and a functional component 22 with a solid boundary.

[0036] For example, functional component 22 is constructed as at least one non-deformable structure, which refers to a component whose shape, size or geometric profile remains fixed and does not change during manufacturing or use.

[0037] When the vertical projection of a functional component 22 coincides with the vertical projection of the main structure of the printed workpiece in any projection plane parallel to the forming surface, the corresponding functional component 22 is equipped with a lifting drive component, and thus can undergo lifting displacement under the action of the lifting drive component. At the same time, the functional components 22 equipped with lifting drive components are driven by independent lifting drive components, that is, the substrate 21 and each functional component 22 can independently undergo lifting motion with a certain displacement.

[0038] In one implementation, such as Figure 4 As shown, the substrate 21 and functional component 22 are configured as a coaxially arranged and nested ring structure, and the corresponding workpiece to be printed is constructed as a single hollow structure with a preset wall thickness. At this time, the workpiece to be printed is a rotating body with a preset wall thickness, and the wall surface has a certain slope.

[0039] In this embodiment, regarding the configuration of the lifting drive component, firstly, the base material 21 is fitted with a corresponding lifting drive component; secondly, regarding the functional component 22, it is necessary to determine based on the distribution of the functional component 22 and the main structure of the printed workpiece, so as to... Figure 4For example, three functional pieces 22 are shown in the figure, including G1, G2, G3 nested in turn from inside to outside, in any projection plane parallel to the forming surface, the vertical projection of G2, G3 and the vertical projection of the printed workpiece body structure overlap, so G2, G3 need to be configured with lifting drive; while G1 and the vertical projection of the printed workpiece body structure do not overlap, so G1 can be directly fixed, of course, it can also be configured with lifting drive.

[0040] As shown in Figure 5 , at this time, multiple functional pieces 22 can be coaxially distributed, after printing, each functional piece 22 has a different height, mainly to fill the space inside the rotating body, maximize the filling of the main invalid space inside the rotating body. The functional pieces 22 are coaxially arranged with the center axis of the rotating body as the reference, forming a ring structure concentric with the wall surface of the printed workpiece, ensuring that the functional pieces 22 occupy space uniformly in the circumferential direction, avoiding the existence of a large amount of powder filling due to eccentricity. At the same time, the design of multiple functional pieces 22 is also to adapt to the spatial changes of the wall surface slope, and a single height formed by a single functional piece 22 cannot efficiently occupy space, so multiple functional pieces 22 are used to form a height gradient, maximizing the space occupancy rate.

[0041] In theory, the more the number of functional pieces 22, the more precise the point-to-point occupation according to the complex profile of the workpiece (such as concave-convex cavity, stepped structure, inclined wall surface) can be achieved, further reducing the amount of powder. But in reality, each functional piece 22 needs to independently complete actions such as "positioning, lifting, fixing", and the increase in the number of functional pieces 22 will significantly increase the system complexity from the aspects of hardware cost, control logic, and mechanical stability, and even have a negative effect on the printing quality. Therefore, for simple structures, for example, regular rotating bodies, generally 3-5 functional pieces 22 can be designed to cover the main invalid space.

[0042] Of course, it needs to be noted that in this application, the core is to further reduce the amount of powder by matching the axial symmetry of the rotating body with the slope characteristics of the wall surface, and using functional pieces 22 with different heights to accurately occupy the invalid space, so as to greatly reduce the amount of powder without the need for complete filling. Therefore, as long as the functional pieces 22 can reduce the amount of powder in the form of physically occupying space, they can have an advantage over traditional structures, and the filler does not need to be completely filled in the area outside the workpiece body structure.

[0043] In this embodiment, the functional pieces 22 are mainly used to fill the internal space of the rotating body, and the outer contour of the base material 21 at the outermost periphery matches the inner contour of the forming bin 1. Figure 5 For example, as shown in (a), when the inner contour of the forming bin 1 is circular, the outer contour of the base material 21 is also circular; as shown in Figure 5For example, in (b) of the above, when the inner contour of the forming bin 1 is square, the outer contour of the base material 21 is also square. Of course, the specific shape is not limited in actual application.

[0044] In other embodiments, the functional pieces 22 can also be distributed in the space outside the rotating body. Since the original volume of the forming bin 1 is the maximum compatible size in the design of the equipment, but the size of the rotating body actually printed is often much smaller than this. By distributing the functional pieces 22 in the space outside the rotating body, the space of the forming bin 1 is optimized to be more suitable.

[0045] For example, when the printed workpiece is a multi-prism structure, the wall surface also presents a shape with a slope. For such a structure, the functional piece 22 is designed as a square ring or a polygonal ring, which can accurately occupy the invalid space through shape adaptability, while considering powder laying compatibility and structural support.

[0046] Based on the disclosure of the above structure, as shown in Figure 6 the specific additive manufacturing method is as follows: S1a, the top surface of the base material 21 and the functional piece 22 is initially reset and has the same height as the powder laying surface; the top surface of the base material 21 and the functional piece 22 constitutes a complete plane in the initial reset state; S2a, before each execution of powder laying, the base material 21 sinks by the same distance as the preset single-layer printing thickness (usually 20-100 μm); after the base material 21 goes down, the powder laying piece 4 performs a powder laying operation, and the powder layer is selectively melted by a focused laser beam to realize intra-layer metallurgical bonding; S3a, when the projection between the area to be laid and the functional piece 22 in the direction perpendicular to the powder laying direction exists overlap, the functional piece 22 starts to move downward at any time before the next powder laying. In the process of layer-by-layer printing, at least part of the top surface of the functional piece 22 gradually protrudes from the top surface of the base material 21 and fills at least part of the area outside the main structure of the printed workpiece.

[0047] Regarding the timing of the start of the downward movement of the functional piece 22 in step S3, it is described in detail as follows: As shown in Figure 7 , still taking the rotating body as an example, the powder laying surface is set as P surface, the base material 21 sinks by the same distance h as the preset single-layer printing thickness before powder laying, and the powder is laid between the P surface and the upper end surface of the base material 21. Then, the powder layer is selectively melted by a focused laser beam to realize intra-layer metallurgical bonding, i.e. the area m in the figure; at this time, the inner diameter of the printed entity is R1, and the outer diameter of the largest functional piece 22 is R2, and R1>R2. In the direction perpendicular to the powder laying direction, there is no overlap between the printed entity and the functional piece 22, and the functional piece 22 does not need to perform action before this time, and remains in the initial state.

[0048] Then, combined with Figure 8As shown, the next layer structure to be printed is region n in the figure. Since the inner diameter of the entity to be printed is R3 and the outer diameter of the largest functional component 22 is R2, and R2 > R3, there will inevitably be overlap between the area to be printed and the functional component 22 in the direction perpendicular to the powder spreading. In order not to affect the powder spreading, the corresponding functional component 22 needs to perform a downward movement synchronously with the substrate 21 before the powder spreading. This powder spreading time is defined as time t. That is to say, the functional component 22 needs to perform the downward movement in advance before time t.

[0049] After the downward movement of functional component 22 is initiated, before each powder spreading operation, functional component 22 and substrate 21 move in tandem, each time moving downwards by the same distance as the preset single-layer printing thickness; otherwise, interference with the printed entity will occur. Furthermore, each downward movement is defined as a time unit.

[0050] Based on the characteristics of the main structure of the printed workpiece, namely that any position on the inner wall is an inclined surface with a slope, in this embodiment, the functional component 22 mainly plays a filling role. Therefore, the functional component 22 can move downwards in one time unit before time t, or it can move downwards in multiple time units before time t.

[0051] Regarding the timing of the downward movement of functional component 22, there are two station relationships between functional component 22 and the printed entity, which places certain requirements on the material selection of functional component 22: The first type, such as Figure 8 As shown, the functional component 22 moves downward one time unit before time t. After the powder is spread and printing is completed at time t, there is direct contact between the functional component 22 and the main structure of the printed workpiece. In order to facilitate the final unloading, the functional component 22 is made of a material that will not be metallurgically bonded to the printed workpiece at least at its top. In addition, the functional component 22 also plays a role in synchronously supporting the printed workpiece to a certain extent.

[0052] The second type, such as Figure 9 As shown, the functional component 22 moves downwards over several time units before time t. During this time, there is a gap between the functional component 22 and the printed workpiece, which is filled with powder. Since the local temperature of the powder can reach thousands of degrees Celsius when it melts, although the functional component 22 is not directly melted by the laser, it needs to withstand high temperatures for a long time. Therefore, its melting point must not be lower than the melting point of the printing material, and it must not undergo significant softening, oxidation, or structural deterioration at high temperatures.

[0053] As for the selection of the base material 21, the chemical composition of the base material 21 needs to be matched with that of the printing material (powder) to reduce the brittle phase generated by element diffusion or reaction and ensure reliable bonding of the part and the substrate; at the same time, the base material 21 has the ability to inhibit thermal deformation and resist thermal stress, so as to avoid warping, cracking or even falling off of the printed workpiece from the base material 21 during the process of the material experiencing rapid heating and cooling cycles. In addition, considering the cost and reusability, in practical applications, the same material base material 21 is the most reliable choice.

[0054] For example, the base material 21 and the functional part 22 are composed of a plurality of movable parts driven independently. The movable part covered by the printing area corresponding to the bottom of the printed workpiece is configured as the base material 21, and the other movable parts are configured as the functional part 22. At this time, before work, the base material 21 and the functional part 22 are not specifically distinguished, and the corresponding base material 21 and functional part 22 are selectively matched according to the shape of the printed workpiece.

[0055] Specifically, as shown in Figure 10 , still taking a rotating body as an example, the forming platform 2 is composed of a plurality of coaxially arranged movable parts, including a, b, c, and d from the inside to the outside. When the printing area corresponding to the bottom of the printed workpiece covers the movable part c, the movable part c serves as the base material 21, and the remaining movable parts a, b, and d serve as the functional part 22. However, the movable parts a and b are used to fill the inner cavity of the printed workpiece, which meets the corresponding process method in S1a-S3a.

[0056] As shown in Figure 11 , when the printing area corresponding to the bottom of the printed workpiece covers the movable part d, the movable part d serves as the base material 21, and the remaining movable parts a, b, and c serve as the functional part 22. However, the movable parts a, b, and C are used to fill the inner cavity of the printed workpiece, which meets the corresponding process method in S1a-S3a.

[0057] It should be noted that since each movable part has the possibility of becoming the base material 21, the selection of the material needs to meet the material compatibility, inhibit thermal stress deformation, resist thermal stress, ensure bonding, cost and reusability. However, the movable part as the functional part 22 cannot be combined with the printed workpiece, otherwise it cannot be removed. Therefore, under the premise of meeting the filling condition, the movable part as the functional part 22 needs to have a gap with the printed workpiece, and the timing of the downward movement of the functional part 22 needs to be advanced by multiple time units before time t.

[0058] For example, the functional part 22 is configured as a plurality of non-deformation structures and is fixedly arranged. As shown in Figure 12 , Figure 13As shown, the functional piece 22 is configured as a plurality of column structures penetrating the base material 21, and the corresponding workpiece to be printed is configured as a plurality of solid structures processed in batches.

[0059] At this time, the specific additive manufacturing method is as follows: S1b, the top surface of the base material 21 and the functional piece 22 is initially reset and has the same height as the powder laying surface; the top surface of the base material 21 and the functional piece 22 constitutes a complete plane in the initial reset state; S2b, before each execution of powder laying, the base material 21 sinks by a distance equal to the preset single-layer printing thickness; after the base material 21 sinks, the powder laying piece 4 performs a powder laying operation, and the powder layer is selectively melted by a focused laser beam to realize intra-layer metallurgical bonding; the functional piece 22 is always in a static state.

[0060] Since the gap between adjacent printed workpieces is filled with a large amount of invalid powder during batch printing, the core function of the functional piece 22 is to replace the powder in the gap with a solid structure to reduce the loss of powder circulation. At the same time, since the printed workpiece is prone to transverse warping (such as bending outward) or twisting due to interlayer thermal stress, the functional piece 22 maintains a small gap with the printed workpiece to avoid adhesion, and suppresses the transverse expansion of the printed workpiece through close-range rigid constraint.

[0061] For example, the functional piece 22 is configured as a plurality of non-deformable structures and is fixedly arranged. As shown in Figure 14 As shown, the functional piece 22 is configured as a plurality of column structures penetrating the base material 21, and the corresponding printed workpiece main structure is configured as a plurality of hollow structures processed in batches.

[0062] Under the premise that the functional piece 22 is fixedly arranged, it is necessary to ensure that the projection of the printed workpiece and the functional piece 22 in the direction perpendicular to the powder laying direction does not overlap, otherwise the continuously descending printed solid part will interfere with the functional piece 22. The functional piece 22 occupies physical space, which can reduce the amount of powder used, and the additive manufacturing method is the same as S1b-S2b.

[0063] For example, the functional piece 22 is configured as at least one non-deformable structure and is driven by the same lifting driving piece, and then undergoes synchronous lifting displacement. As shown in Figure 15 As shown, the functional piece 22 is configured as a plurality of column structures penetrating the base material 21, and the corresponding workpiece to be printed is configured as a plurality of hollow structures processed in batches, or overhanging structures.

[0064] As shown in Figure 15As shown, taking a hollow printed workpiece as an example, the projection of the printed workpiece and the functional component 22 in the direction perpendicular to the powder spreading direction overlaps. During the layer-by-layer printing process, when the projection of the area to be powdered and the functional component 22 in the direction perpendicular to the powder spreading direction overlaps, the functional component 22 moves downward in advance before the next powder spreading, which mainly serves to reduce the amount of powder used.

[0065] like Figure 16 As shown, taking a single overhanging structure as an example, an overhanging structure refers to a structure in a workpiece that extends outwards, and the extended portion lacks sufficient underlying solid support. Simply put, it's a part that "hangs outwards in mid-air," its core characteristic being lateral extension without underlying solid support. For example, n-shaped structures and H-shaped structures can both be considered overhanging structures.

[0066] At this time, functional component 22 provides physical support, suppressing deformation of the printed workpiece, and also playing an advantage in reducing powder consumption. During the printing process, when the projection of the area to be powdered and the functional component in the direction perpendicular to the powder spreading coincides, functional component 22 begins its downward movement one time unit in advance.

[0067] The specific additive manufacturing method at this point is as follows: S1c, the top surface of the substrate 21 and the functional component 22 are initially reset and have the same height as the powder-coated surface; the top surface of the substrate 21 and the functional component 22 form a complete plane in the initial reset state. S2c, When the height of the functional component 22 protruding from the substrate 21 is less than the actual height of the bottom surface of the suspended structure, before each powder spreading operation, the substrate 21 sinks to the same distance as the preset single-layer printing thickness; after the substrate 21 sinks, the powder spreading component 4 performs a powder spreading operation, selectively melting the powder layer with a focused laser beam to achieve metallurgical bonding within the layer; S3c, When the height of the functional component 22 protruding from the substrate 21 is equal to the actual height of the bottom surface of the suspended structure, that is, before the projection of the printing area and the functional component 22 perpendicular to the powder-spreading direction coincides during the next powder-spreading printing, the functional component 22 and the substrate 21 move downward synchronously. At this time, the functional component 22 provides rigid support for the suspended structure. In other words, the moment when the projection between the powder-spreading printing area and the functional component 22 coincides is defined as time t. The functional component 22 needs to move downward one time unit before time t. Only after the functional component 22 moves downward can powder be spread on it, and only then can the subsequent printing be completed.

[0068] In this embodiment, the overhang structure is printed directly onto the functional component 22, avoiding the presence of loose powder between the overhang structure and the functional component 22, as loose powder provides only very weak support. In this case, the functional component 22 primarily serves a supporting function, while also acting as a filler, reducing powder usage.

[0069] For example, the functional part 22 is configured as a part that can be combined with the printed workpiece body structure, and when the projection of the to-be-powder-laid printing area and the functional part 22 in the direction perpendicular to the powder laying direction overlaps, the functional part 22 moves downward by one time unit in advance. At this time, the to-be-powder-laid printing area and the functional part 22 still overlap in the direction perpendicular to the powder laying direction, and the functional part 22 is still combined with the printed workpiece body structure. Figure 16 As shown in the figure, only the function of the functional part 22 changes from supporting to being able to be combined with the printed workpiece body structure.

[0070] At this time, the specific additive manufacturing method is as follows: S1d, embedding the printed functional part 22 into the forming bin in advance; S2d, in the initial state, the top surface of the base material 21 and the functional part 22 is reset and has the same height as the powder laying surface; the top surface of the base material 21 and the functional part 22 constitutes a complete plane in the initial reset state; it should be noted that at this time, the printed workpiece body structure has an end surface combined with the functional part 22, which is defined as a combined surface, so the projection of the functional part 22 in the direction perpendicular to the powder laying direction must overlap with the projection of the end surface, otherwise the two cannot be combined during printing; S3d, when the height of the functional part 22 protruding from the base material 21 is less than the actual height of the combined surface, the base material 21 sinks by a distance equal to the preset single-layer printing thickness before each powder laying is performed; after the base material 21 moves downward, the powder laying part 4 performs a powder laying operation, and the powder layer is selectively melted by the focused laser beam to realize intra-layer metallurgical bonding; S4d, when the height of the functional part 22 protruding from the base material 21 is equal to the actual height of the combined surface, that is, before the to-be-powder-laid printing area and the functional part 22 overlap in the direction perpendicular to the powder laying direction, the functional part 22 moves downward synchronously with the base material 21, and at this time, the functional part 22 and the combined surface can be metallurgically combined, and the two constitute a whole. That is, the time when the projection of the to-be-powder-laid printing area and the functional part 22 overlaps is defined as time t, and the functional part 22 needs to move downward by one time unit in advance before time t, and after the functional part 22 moves downward, powder can be laid above it, and then subsequent printing forming can be completed.

[0071] In the above example, the functional part 22 adopts a non-deformation structure made of a rigid material, and its size can be matched with the printed workpiece efficiently, and its shape does not change during printing, so that the structural stability and supporting performance can be fully utilized, the reusability is high, and the size precision is controllable. The present application further provides a flexible functional part 22, which will be described below.

[0072] For example, the functional part 22 is configured as a deformation structure and is driven by an independent medium filling device to deform. For example, the functional part 22 can adopt an air bag, and the medium filling device is used to fill gas into the air bag.

[0073] As Figure 17 shown, the functional part 22 and the base material 21 are driven by the same lifting drive and follow the lifting; after the base material 21 has n times of sinking movement, the functional part 22 has one deformation.

[0074] Specifically, taking the rotating body as an example, the functional part 22 is used to fill the space inside the rotating body in the process of layer-by-layer printing. Structurally, a cavity is formed on the base material 21, and the functional part 22 is installed in the cavity. Since the air bag itself has an irregular shape, its shape change is also irregular in the process of gradual inflation deformation, and only the top part can gradually rise with the increase of the inflation amount. In each powder laying process, it is only necessary to ensure that the upper end of the air bag does not protrude from the powder laying surface.

[0075] At this time, the specific additive manufacturing method is as follows: S1e, the top surface of the base material 21 and the functional part 22 is initially reset and has the same height as the powder laying surface; in this state, since the functional part 22 has an irregular structure, it cannot be ensured that the top surface is at the same height, and it cannot be ensured that the top surface of the base material 21 and the top surface of the functional part 22 can form a complete plane; S2e, before each powder laying, the base material 21 sinks by a distance equal to the preset single-layer printing thickness, and the functional part 22 synchronously descends with the base material 21, and it is ensured that the upper end of the functional part 22 does not protrude from the powder laying surface during each powder laying; S3e, after the base material 21 has n times of sinking movement, the functional part 22 has one deformation, and n is generally set to 50-100; for example, when the preset single-layer printing thickness is 50 μm and n is 50, the functional part 22 completes one inflation when the base material 21 descends by 2.5 mm.

[0076] Since the air bag as the functional part 22 is always in the forming bin 1, it must be able to adapt to the environmental conditions in the forming bin 1. In metal printing, the laser molten pool temperature can reach 1500-3000℃ (such as about 2500℃ for titanium alloy and about 2000℃ for high-temperature alloy), the air bag does not directly contact the molten pool, but will be subjected to strong heat radiation, especially when it is close to the printing area, and the overall temperature of the forming bin 1 can rise to 100-500℃, so the functional part 22 must have temperature resistance and thermal stability to avoid problems such as air leakage or distortion. At the same time, metal printing is usually carried out in an inert atmosphere or a vacuum environment, and may contact metal powder and trace volatile substances, so the air bag needs to have gas corrosion resistance, and the surface of the air bag should avoid physical adsorption or chemical combination with the powder, otherwise it may contaminate the powder or cause the powder to agglomerate, affecting the uniformity of subsequent powder laying. In addition, as the functional part 22, the air bag needs to maintain a stable shape during powder laying and printing, while bearing the contact pressure of the powder laying part 4, the extrusion of the powder, and its own inflation pressure. The powder laying part 4 may slightly contact the surface of the air bag during powder laying, so the air bag needs to have a certain hardness to avoid being scratched by sharp powder particles or the powder laying part 4.

[0077] In theory, the air bag will gradually fill the space in the middle of the printed workpiece during the process of gradually increasing inflation, thereby reducing the amount of powder. However, in actual application, as shown in Figure 18 , due to the deformation of the upper end surface of the air bag, the middle part will bulge and the peripheral side will collapse, and in the process of gradually laying powder and printing, the peripheral side of the upper end of the air bag will be extruded by the entity that has been printed (as shown in Figure 18 Q area) during the inflation of the air bag, thereby exerting a force on the entity that has been printed, and even damaging the structure, so the air bag cannot be inflated indefinitely.

[0078] For example, the functional part 22 is configured as a deformed structure, as shown in Figure 19 , the functional part 22 and the base material 21 are driven by independent lifting driving parts, and after the base material 21 undergoes n times of sinking movement, the functional part 22 undergoes one time of deformation.

[0079] At this time, the specific additive manufacturing method is: S1f, the top surface of the base material 21 and the functional part 22 is initially reset and has the same height as the powder laying surface; in this state, since the functional part 22 is an irregular structure, it cannot be fully on the same height, and therefore it cannot form a complete plane with the top surface of the base material 21; S2f, before each powder laying, the base material 21 sinks by a distance equal to the preset single-layer printing thickness, and the functional part 22 and the base material 21 sink synchronously, and the uppermost end of the functional part 22 does not protrude from the powder laying surface during each powder laying; S3f, after n times of down movement of the substrate 21, the functional part 22 is driven to move down alone relative to the substrate 21, so that the powder accumulated above the functional part 22 slides down; Figure 20 As shown in the figure, the functional part 22 is driven to move down alone relative to the substrate 21, so that the powder accumulated above the functional part 22 slides down; S4f, the functional part 22 moves up to reset, and the medium filling device is started to make the at least partial upper end surface of the functional part 22 at the same height as the powder laying surface. At this time, the maximum inflation amount of the air bag can be achieved, and the phenomenon that the upper end of the air bag is squeezed by the printed entity can not occur.

[0080] The above S3e-S4e is repeated, and after n times of down movement of the substrate 21, the functional part 22 moves down once to slide the powder and deform. Generally, n is set to 50-100.

[0081] The functional part 22 made of the high-temperature-resistant flexible material has the dynamic shape change ability by gradually filling the medium into the gap between the printed workpiece. Since it has the characteristics of middle bulging and four sides collapsing in the expanded state, it is more suitable for the printing scene of large workpieces (especially thin-walled rotating bodies).

[0082] In all the above exemplary schemes, the amount of powder is reduced compared with the traditional planar substrate structure, but there is still powder to be recycled. The recycled powder needs to be treated before being reused due to physical contamination, chemical and microstructure changes, particle size distribution deviation and other problems. The recycled powder needs to be screened to remove lumps or oversized particles, decontaminated to remove residual support materials or carbides, and sometimes mixed with fresh powder in proportion to ensure the printing quality. Of course, if the powder is severely oxidized, impurities are contaminated, or the particle size distribution is uncontrollable after multiple cycles, it needs to be discarded.

[0083] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. For those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

Claims

1. A method of additive manufacturing, characterized by, include: It is configured with a substrate having a shaped surface and functional parts having solid boundaries; The top surface of the substrate and functional components is initially reset and has the same height as the powder-coated surface; During the printing process, at least a portion of the top surface of the functional component protrudes from the top surface of the substrate and is housed in at least a portion of the area outside the main structure of the printed workpiece.

2. The additive manufacturing method of claim 1, wherein: When the vertical projection of the functional component coincides with the vertical projection of the main structure of the printed workpiece in any projection plane parallel to the forming surface, the corresponding functional component is equipped with a lifting drive component.

3. The additive manufacturing method of claim 2, wherein: The functional component is constructed as at least one non-deformable structure, and the functional component equipped with a lifting drive is driven by an independent lifting drive, thereby causing lifting displacement.

4. The additive manufacturing method of claim 3, wherein: During the printing process, when the projection of the area to be printed with toner and the functional component in the direction perpendicular to the toner spreading overlaps, the functional component will move downward in advance. After the downward movement of the functional component is activated, before each powder spreading operation, the functional component moves in tandem with the substrate, moving down a distance equal to the preset single-layer printing thickness; and each downward movement is defined as a time unit.

5. The additive manufacturing method of claim 4, wherein: The functional component is used to perform the filling function. When the projection of the area to be printed with toner and the functional component in the direction perpendicular to the toner spreading direction overlaps, the functional component will move downward at any time in advance.

6. The additive manufacturing method of claim 4, wherein: The functional component is used to perform the support function. When the projection of the area to be printed and the functional component in the direction perpendicular to the powder spreading direction overlaps, the functional component moves downward one time unit in advance.

7. The method of additive manufacturing according to claim 4, wherein: The functional component is constructed as part of the main structure of the printed workpiece. When the projection of the area to be powdered and printed and the functional component in the direction perpendicular to the powder spreading overlaps, the functional component moves downward one time unit in advance.

8. The method of additive manufacturing according to claim 5, wherein: When the functional component moves downward one time unit in advance, there is direct contact between the functional component and the printed workpiece. The functional component is made of a material that will not be metallurgically bonded to the main structure of the printed workpiece at least at its top, and the functional component also supports the main structure of the printed workpiece simultaneously. When the functional component moves downward two or more time units in advance, there is a gap between the functional component and the printed workpiece, which is filled with powder. The functional component is made of a material with a melting point not lower than that of the powder.

9. The method of additive manufacturing according to claim 3, wherein: The functional component is constructed as a deformable structure and is driven by an independent medium filling device, thereby undergoing deformation.

10. The additive manufacturing method of claim 9, wherein: The functional component and the substrate are driven by independent lifting drive components. After the substrate undergoes n sinking movements, the functional component undergoes one deformation.

11. The additive manufacturing method of claim 10, wherein, The lifting control method for the functional component is as follows: The functional component moves with the substrate and undergoes n sinking movements; The functional component is driven individually to move downward relative to the substrate, causing the powder accumulated above the functional component to slide off. The functional component is reset upwards and the medium filling device is activated, so that at least part of the upper surface of the functional component is at the same height as the powder-coated surface; the above actions are repeated in this manner.

12. The method of additive manufacturing according to claim 9, wherein: The functional component and the substrate are driven by the same lifting drive component and move up and down accordingly; after the substrate undergoes n sinking movements, the functional component undergoes one deformation.

13. An additive manufacturing apparatus, characterized by For performing the additive manufacturing method according to any one of claims 1-12, comprising: A molding chamber, wherein a molding platform is configured inside the molding chamber, the molding platform including a base material having a molding surface and a functional component having a solid boundary; The powder hopper contains the powder to be laid and is driven to cause the powder to overflow or detach from the powder hopper. The powder spreading component moves back and forth within the powder spreading surface, spreading the powder in the powder hopper evenly above the molding hopper; A high-energy beam generator is used to emit laser or electron beams and irradiate powder above a forming platform to selectively melt the powder.

14. The additive manufacturing apparatus of claim 13, wherein: The functional component is constructed as at least one non-deformable structure. Each functional component equipped with a lifting drive is driven by an independent lifting drive. The substrate and the top surface of the functional component form a complete plane in the initial reset state.

15. The additive manufacturing apparatus of claim 14, wherein: The substrate and functional components are configured as a ring structure that is coaxially arranged and nested in sequence, and the corresponding printed workpiece main structure is constructed as a single hollow structure with a preset wall thickness.

16. The additive manufacturing apparatus of claim 14, wherein: The functional component is configured as multiple column structures penetrating the substrate, and the corresponding printed workpiece main structure is constructed as multiple solid structures or hollow structures processed in batches.

17. The additive manufacturing apparatus of claim 14, wherein: The substrate and functional components are composed of several independently driven movable components. The movable component covered by the printing area corresponding to the bottom of the main structure of the printed workpiece is constructed as the substrate, and the other movable components are constructed as the functional components.

18. The additive manufacturing apparatus of claim 13, wherein: The functional component is constructed as a deformable structure and is placed in an accommodating space within the substrate. The functional component is connected to a medium filling device.

19. The additive manufacturing equipment according to claim 18, characterized in that: The functional component is fixed inside the substrate and is driven by a lifting drive component to generate synchronous vertical displacement.

20. The additive manufacturing equipment according to claim 18, characterized in that: The functional component is movably fitted within the substrate, and the functional component and the substrate each have independent lifting drive components.

21. A molding platform as described in any one of claims 13-20, characterized in that, This includes substrates with shaped surfaces and functional components with solid boundaries.

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