A three-dimensional forming system for large cross-section metal entities

Abstract

The present invention relates to the technical field of three-dimensional forming of metal entities, and provides a three-dimensional forming system for large-section metal entities, which includes a frame. A forming chamber is fixedly connected to the inner side of the frame. A powder supply unit is arranged at the top of the forming chamber. A powder spreading unit is arranged inside the forming chamber. A powder bed is arranged on the bottom plate of the forming chamber. A first pseudo powder bed is fixedly connected to one end of the bottom plate of the forming chamber, and a second pseudo powder bed is fixedly connected to the other end of the bottom plate of the forming chamber. A powder recycling unit is arranged at one end of the forming chamber, and the powder inlet of the powder recycling unit is fixedly connected to the bottom plate of the forming chamber. An atmosphere unit is arranged at one end inside the frame, and a scanning unit is arranged at the top of the forming chamber. The implementation of the present invention is simple, the powder spreading disturbance is small, the single-layer powder on the surface of the powder bed is flat and uniform, the forming accuracy is high, the strength is good, and it is easy to be popularized and applied in various high-precision, medium and large-sized laser and electron beam metal powder bed three-dimensional forming equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional forming of metal entities. Specifically, it relates to a three-dimensional forming system for large-section metal entities. Background Art

[0002] Laser and electron beam metal powder bed forming technology is one of the main methods in the field of additive manufacturing. Based on the layer-by-layer laying of metal powder on the forming cylinder substrate, a laser or electron beam scans the selected area of the powder bed to melt and polymerize it, cool and solidify it, and deposit it on the substrate. Then, through the repeated execution of the steps of the substrate descending layer by layer, powder laying, and scanning, the deposit grows layer by layer on the substrate until the whole is completely formed. Since the metal powder in the non-scanned area better fills the redundant space of the forming cylinder, the deposit growth process layer by layer has good support and heat dissipation conditions, and the flat powder bed surface ensures the accurate selection of the scanning area. This makes laser and electron beam powder bed forming equipment show outstanding advantages in the forming of precision and complex metal structure parts. Existing metal powder bed forming equipment mainly includes SLM (selective laser melting) equipment and EBM (electron beam melting) equipment. Among them, SLM is mainly used for three-dimensional forming of conventional metal powder materials, and EBM is mainly used for three-dimensional forming of refractory metal powder materials.

[0003] It is easy to infer that laying metal powder with a uniform and controllable thickness layer by layer on the powder bed is the primary prerequisite for accurately generating a single-layer metal deposit. Abnormal powder laying thickness directly leads to poor process, including defects such as insufficient melting and ablation. In severe cases, the forming process will be forced to terminate. The existing powder laying devices generally use a linear module to drive a scraper to push the powder pile forward, and adjust the powder laying thickness through the gap between the scraper and the powder bed surface. Therefore, the normal powder laying state must depend on the following conditions: First, the powder has good fluidity to ensure that the powder laying thin layer does not crack when the scraper pushes the powder pile forward; Second, the viscous effect between the powder pile and the powder bed surface is moderate to ensure that a single layer of powder is sufficient to overcome the shear force generated by the scraper pushing the powder pile; Third, the scraper has necessary rigidity and self-lubricity to avoid crawling and jitter caused by friction with the bottom plate of the forming chamber and the powder bed surface.

[0004] In a practical environment, it is difficult to fully meet the above conditions. For example, there are obvious differences in the viscous effects on the powder pile between the metal deposition area and the powder area on the surface of the powder bed; when the area of the metal deposition is large, powder displacement and uneven distribution will occur when powder is laid on its surface. In addition, during the powder laying process of the linear module, the scraping bar friction pair's coupling element needs to drive the scraper through multiple functional areas such as powder supply, powder bed, and powder recycling. The coupling element of the scraping bar friction pair switches between the metal plate, the powder surface, and the metal deposition surface multiple times, which will cause sudden changes in the characteristics of the friction pair, and then cause powder surface ripples. Uneven powder laying and powder surface ripples will directly interfere with the accuracy of the scanning energy strategy of the laser and electron beam, and leave obvious defect characteristics on the formed metal part, thereby restricting the development potential of SLM and EBM equipment for manufacturing large-size and large-cross-section precision complex metal parts. Problems such as difficult powder laying for large cross-sections, large scanning thermal stress, poor forming accuracy, and low success rate have become one of the main bottlenecks restricting the development of the high-end metal additive manufacturing industry, and there is no effective technical solution; it has been reported that based on changing the forming attitude, the vertical projection area (i.e., the sliced area) of the large cross-section part is reduced by tilting, but this will greatly increase the number of forming layers and process risks. Currently, in the field of metal powder bed forming technology, there is still a lack of a three-dimensional forming method that can effectively solve the precision and reliable manufacturing of large cross-section metal solid parts. In view of this, the present invention proposes a three-dimensional forming system for large cross-section metal solids. Summary of the Invention

[0005] The present invention proposes a three-dimensional forming system for large cross-section metal solids, which solves the problems of difficult powder laying for large cross-sections, large scanning thermal stress, poor forming accuracy, and low success rate in the prior art.

[0006] The technical solution of the present invention is as follows: A three-dimensional forming system for large cross-section metal solids includes a frame. Inside the frame, a forming chamber is fixedly connected. At the top of the forming chamber, there is a powder supply unit for quantitatively outputting metal powder into the forming chamber. Inside the forming chamber, there is a powder laying unit for horizontally reciprocating powder laying on the bottom plate of the forming chamber. On the bottom plate of the forming chamber, there is a powder bed, and the opening of the powder bed is fitted on the bottom plate of the forming chamber. At one end of the bottom plate of the forming chamber, a first pseudo-powder bed is fixedly connected, and at the other end of the bottom plate of the forming chamber, a second pseudo-powder bed is fixedly connected. The first pseudo-powder bed is connected in parallel with one side of the powder bed, and the second pseudo-powder bed is connected in parallel with the other side of the powder bed. At one end of the forming chamber, there is a powder recycling unit, and the powder inlet of the powder recycling unit is fixedly connected to the bottom plate of the forming chamber, and the powder recycling unit is located on one side of the second pseudo-powder bed. At one end inside the frame, there is an atmosphere unit for filtering and purifying the gas inside the forming chamber. At the top of the forming chamber, there is a scanning unit for scanning the metal powder on the surface of the powder bed.

[0007] Preferably, one end of the atmosphere unit is provided with an air inlet, and the other end of the atmosphere unit is provided with an air outlet. The air inlet is connected to the gas outlet of the forming chamber, and the air outlet is connected to the gas inlet of the forming chamber.

[0008] Preferably, the first pseudo powder bed is located between the powder supply unit and the powder bed, and the second pseudo powder bed is located between the powder bed and the powder return unit.

[0009] Preferably, a controller is fixedly connected to the inner side of the frame. The powder supply unit, the powder spreading unit, the powder bed, the atmosphere unit, and the scanning unit are all electrically connected to the controller.

[0010] Preferably, a large cross-section metal solid three-dimensional forming system further includes a three-dimensional forming manufacturing method, and the specific steps are as follows:

[0011] S1: Before forming, first inject a sufficient amount of metal powder into the powder supply unit, close the forming chamber, and the controller sends an operation instruction to the atmosphere unit to control the atmosphere unit to adjust the atmosphere environment of the forming chamber to an inert state, and then maintain the circulating purification operation;

[0012] S2: The controller sends a reference point instruction to the powder bed to control the powder bed to drive the substrate to rise to a preset height. The controller sends a reference point instruction to the powder spreading unit to control the powder spreading unit to return to a preset position. The controller sends a pre-powder supply instruction to the powder supply unit to control the powder supply unit to output the metal powder required for pre-powder spreading to the powder spreading unit. The controller sends a pre-powder spreading instruction to the powder spreading unit to control the linear module of the powder spreading unit to push the powder pile to sequentially pass through the first pseudo powder bed, the powder bed, and the second pseudo powder bed, so that the powder in the first pseudo powder bed and the second pseudo powder bed is filled to be flush with the bottom plate of the forming chamber. The powder spreading unit continues to push the remaining powder of the powder pile into the powder inlet of the powder return unit and then returns to the preset position. The controller loads the three-dimensional slice data of the component to be formed;

[0013] S3: During the first layer forming, the controller first sends a lowering instruction to the powder bed and a powder supply instruction to the powder supply unit to drive the substrate to descend by a unit height and drive the powder supply unit to output the metal powder required for single powder spreading to the powder spreading unit respectively. The controller sends a powder spreading instruction to the powder spreading unit to control the linear module of the powder spreading unit to perform a powder spreading action, that is, to push the powder pile to fill the depression on the upper surface of the powder bed generated by the descent of the substrate and push the remaining powder into the powder return unit. The controller reads the first layer slice data, generates a corresponding scanning instruction and sends it to the scanning unit to control the scanning unit to perform an energy scanning action. The metal powder in the scanned area of the powder bed is melted and polymerized, cooled and solidified to generate the first layer of metal deposit and is tightly welded to the substrate. The controller controls the powder spreading unit to return to the preset position, and the first layer forming process is completed;

[0014] S4: The subsequent forming process is the same as that of the first layer. The controller first issues a descending command to the powder bed and a powder supply command to the powder supply unit, and the execution unit performs the descending action of the unit height and the powder supply action; the controller issues a powder spreading command to the powder spreading unit, and the powder spreading action is performed; the controller reads the single-layer slice data and controls the scanning unit to perform the energy scanning action, and the single-layer metal deposit generated by the energy scanning is tightly welded to the previous layer of metal deposit; the controller controls the powder spreading unit to return to the preset position; the above steps of substrate descending, powder supply, powder spreading, scanning, and the powder spreading unit returning to the preset position are cyclically executed, and the single-layer metal deposits generated are welded layer by layer on the substrate until all the slice layer data of the component is formed, and the generated three-dimensional component is welded on the substrate.

[0015] Preferably, in S3 and S4 of the three-dimensional forming manufacturing method, when the linear module of the powder spreading unit pushes the powder pile forward to spread the powder, the scraping bar first forms a flexible-rigid friction pair with the bottom plate of the forming chamber, and then forms a flexible-flexible friction pair with the powder surface of the first pseudo-powder bed, so that when the scraping bar enters the powder bed area, the friction pair characteristics of the scraping bar remain stable, and thus ensure that the powder spreading surface near the edge of the first pseudo-powder bed is flat and undisturbed.

[0016] Preferably, in S3 and S4 of the three-dimensional forming manufacturing method, after the powder spreading unit finishes spreading the powder through the opening of the powder bed and the scraping bar leaves the powder bed area, it continues to maintain a flexible-flexible friction pair with the powder surface of the second pseudo-powder bed, so that when the scraping bar leaves the powder bed area, the friction pair characteristics of the scraping bar remain stable, and thus ensure that the powder spreading surface near the edge of the second powder bed is flat and undisturbed.

[0017] Preferably, in S3 and S4 of the three-dimensional forming manufacturing method, the typical powder depth of the first pseudo-powder bed and the second pseudo-powder bed is 1 mm - 5 mm, and the typical width is 10 mm - 30 mm. Only need to fill the metal powder to the height flush with the bottom plate of the forming chamber in the pre-powder spreading step, and no additional metal powder consumption occurs during the layer-by-layer forming process.

[0018] Preferably, in S3 and S4 of the three-dimensional forming manufacturing method, when the scanning unit reads and processes the slice layer data inside the component, it first splits the complete solid surface into nested complementary A and B sub-unit arrays in a rectangular grid mode, where each of the A and B sub-unit arrays accounts for one-half of the total area, and completes the forming of the single-layer slice data in the way of first spreading the powder and scanning the A sub-unit array, and then spreading the powder and scanning the B sub-unit array. The substrate of the powder bed descends by a unit height each time, which is one-half of the thickness of the slice data, and the thickness of the metal deposits formed by scanning the A and B sub-unit arrays respectively is consistent with the layer thickness of the slice data.

[0019] Preferably, the scanning method of the A and B sub-unit arrays is as follows:

[0020] S1. The substrate descends by a unit height. The powder supply unit supplies a required fixed amount of powder for a single powder spreading to the powder spreading unit, and forms a powder pile on the right side of the doctor blade.

[0021] S2. The powder spreading unit drives the doctor blade to push the powder pile to perform a powder spreading action, generating a first powder layer on the upper surface of the powder bed, where the thickness is large at the A sub-unit array and small at the B sub-unit array.

[0022] S3. The scanning unit performs an energy scan on the A sub-unit array of the Nth layer slice data; the powder spreading unit returns to a preset position.

[0023] S4. Repeat the scanning method S1. The powder spreading unit drives the doctor blade to push the powder pile to perform a powder spreading action, generating a second powder layer on the upper surface of the powder bed, where the thickness is large at the B sub-unit array and small at the A sub-unit array.

[0024] S5. The scanning unit performs an energy scan on the B sub-unit array of the Nth layer slice data, where the upper surface area incorporated from the A sub-unit array adopts the upper surface energy scan parameters; the powder spreading unit returns to a preset position; the forming of the Nth layer slice data is completed.

[0025] The working principle and beneficial effects of the present invention are as follows:

[0026] 1. The present invention eliminates the sudden change disturbance of the friction parameters of the doctor blade when the doctor blade of the powder spreading unit enters and exits the powder bed through the first pseudo powder bed and the second pseudo powder bed, and splits the large cross-section slice layer data into mutually nested sub-unit arrays, spreads the powder twice and scans separately, so as to solve the problem of difficult powder spreading on the upper surface of large cross-section metal deposits, and further ensure the powder spreading accuracy of the powder bed and the accuracy of the generated single-layer metal deposit.

[0027] 2. By splitting the large cross-section layer slice data into mutually nested sub-unit arrays and alternately scanning by spreading the powder twice, the present invention also has the functions of dispersing the thermal stress of the energy scan and forming an interlayer nested structure, which has a positive effect on reducing the thermal stress deformation and improving the interlayer strength.

[0028] 3. The implementation of the present invention is simple, the powder spreading disturbance is small, the single-layer powder on the surface of the powder bed is flat and uniform, the forming accuracy is high, the strength is good, and it is easy to be popularized and applied in various high-precision, medium and large-sized laser and electron beam metal powder bed three-dimensional forming equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0030] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0031] Figure 2 It is a connection diagram of control signals of an embodiment of the present invention;

[0032] Figure 3 Schematic diagram of powder spreading operation according to an embodiment of the present invention;

[0033] Figure 4 Schematic diagram of layer-by-layer energy scanning forming according to an embodiment of the present invention.

[0034] In the figure: 1, frame; 2, forming chamber; 3, powder supply unit; 31, powder pile; 4, powder spreading unit; 41, scraper; 5, powder bed; 51, substrate; 501, first powder layer; 502, second powder layer; 6, first pseudo powder bed; 7, second pseudo powder bed; 8, powder recycling unit; 9, atmosphere unit; 91, air inlet; 92, air outlet; 10, scanning unit; 100, controller; 200, large cross-section metal deposit. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] As Figure 1-2 shown, this embodiment proposes a large cross-section metal solid three-dimensional forming system, including a frame 1. The inner side of the frame 1 is fixedly connected with a forming chamber 2. The top of the forming chamber 2 is provided with a powder supply unit 3 for quantitatively outputting metal powder to the forming chamber 2. The inner side of the forming chamber 2 is provided with a powder spreading unit 4 for horizontally reciprocatingly spreading powder on the bottom plate of the forming chamber 2. The bottom plate of the forming chamber 2 is provided with a powder bed 5. The opening of the powder bed 5 is fitted into the bottom plate of the forming chamber 2. One end of the bottom plate of the forming chamber 2 is fixedly connected with a first pseudo powder bed 6, and the other end of the bottom plate of the forming chamber 2 is fixedly connected with a second pseudo powder bed 7. The first pseudo powder bed 6 is connected in parallel with one side of the powder bed 5, and the second pseudo powder bed 7 is connected in parallel with the other side of the powder bed 5. One end of the forming chamber 2 is provided with a powder recycling unit 8. The first pseudo powder bed 6 is located between the powder supply unit 3 and the powder bed 5, and the second pseudo powder bed 7 is located between the powder bed 5 and the powder recycling unit 8. The powder inlet of the powder recycling unit 8 is fixedly connected with the bottom plate of the forming chamber 2, and the powder recycling unit 8 is located on one side of the second pseudo powder bed 7. One end of the inner side of the frame 1 is provided with an atmosphere unit 9 for filtering and purifying the gas inside the forming chamber 2. One end of the atmosphere unit 9 is provided with an air inlet 91, and the other end of the atmosphere unit 9 is provided with an air outlet 92. The air inlet 91 is connected to the gas outlet of the forming chamber 2, and the air outlet 92 is connected to the gas inlet of the forming chamber 2. The top of the forming chamber 2 is provided with a scanning unit 10 for scanning the metal powder on the surface of the powder bed 5.

[0037] A controller 100 is fixedly connected to the inner side of the frame 1. The powder feeding unit 3, the powder spreading unit 4, the powder bed 5, the atmosphere unit 9, and the scanning unit 10 are all electrically connected to the controller 100. The controller 100 sends an electrical signal to the powder feeding unit 3 to control the powder feeding unit 3 to output a required fixed amount of metal powder for powder spreading to the powder spreading unit 4. The controller 100 sends an electrical signal to the powder spreading unit 4 to control the powder spreading unit 4 to drive the squeegee of the linear module to perform a powder spreading action from left to right and a returning to the preset position action from right to left. The controller 100 sends an electrical signal to the powder bed 5 to control the powder bed 5 to drive the substrate 51 to move up to a preset height before component forming and then to descend by a unit height before powder spreading layer by layer. The controller 100 sends an electrical signal to the atmosphere unit 9 to control the atmosphere unit 9 to adjust the atmosphere in the forming chamber 2 to an inert environment and maintain the cyclic purification of the atmosphere in the forming chamber 2. The controller 100 sends an electrical signal to the scanning unit 10 to control the scanning unit 10 to perform an energy scanning action on a selected area on the surface layer of the powder bed 5 according to parameters such as set power, speed, and focus diameter.

[0038] By means of the first pseudo powder bed 6 and the second pseudo powder bed 7, the sudden change disturbance of the scraping friction parameters of the squeegee when the squeegee of the powder spreading unit 6 enters and exits the powder bed 5 is eliminated, and the large cross-section slice layer data is split into an array of nested sub-units, and powder spreading is performed twice and scanned separately to solve the problem of difficult powder spreading on the large cross-section metal deposit 200, thereby ensuring the powder spreading accuracy of the powder bed 5 and the accuracy of the generated single-layer metal deposit; by splitting the large cross-section layer slice data into an array of nested sub-units and alternately scanning by powder spreading twice, it also has the function of dispersing the thermal stress of the energy scanning and forming an interlayer nested structure, which has a positive effect on reducing thermal stress deformation and enhancing interlayer strength.

[0039] The present invention also provides a three-dimensional forming manufacturing method for a large cross-section metal entity, including the following steps:

[0040] S1: Before forming, first inject a sufficient amount of metal powder into the powder feeding unit 3 and close the forming chamber 2. The controller 100 sends an operation instruction to the atmosphere unit 9 to control the atmosphere unit 9 to adjust the atmosphere environment in the forming chamber 2 to an inert state, and then maintain the cyclic purification operation;

[0041] S2: The controller 100 issues a reference point command to the powder bed 5, controls the powder bed 5 to drive the substrate 51 to rise to a preset position, the controller 100 issues a reference point command to the powder spreading unit 4, controls the powder spreading unit 4 to return to a preset position, the controller 100 issues a pre-powder supply command to the powder supply unit 3, controls the powder supply unit 3 to output the metal powder required for pre-powder spreading to the powder spreading unit 4, the controller 100 issues a pre-powder spreading command to the powder spreading unit 4, controls the linear module of the powder spreading unit 4 to push the powder pile 31 to sequentially pass through the first pseudo powder bed 6, the powder bed 5, and the second pseudo powder bed 7, so that the powder in the first pseudo powder bed 6 and the second pseudo powder bed 7 is filled to be flush with the bottom plate of the forming chamber 2. Among them, the typical powder depth of the first pseudo powder bed 6 and the second pseudo powder bed 7 is 1 mm - 5 mm, and the typical width is 10 mm - 30 mm. Only the metal powder needs to be filled to the height flush with the bottom plate of the forming chamber 2 in the pre-powder spreading step, and no additional metal powder consumption occurs during the layer-by-layer forming process. The powder spreading unit 4 continues to push the remaining powder of the powder pile 31 into the powder inlet of the powder returning unit 8 and then returns to the preset position. The controller 100 loads the three-dimensional slice data of the component to be formed;

[0042] S3: During the first layer forming, the controller 100 first issues a descending command to the powder bed 5 and a powder supply command to the powder supply unit 3, respectively driving the substrate 51 to descend by a unit height and driving the powder supply unit 3 to output the metal powder required for single powder spreading to the powder spreading unit 4; the controller 100 issues a powder spreading command to the powder spreading unit 4, controls the linear module of the powder spreading unit 4 to perform a powder spreading action, that is, to push the powder pile 31 to fill the depression on the upper surface of the powder bed 5 generated by the descent of the substrate 51, and push the remaining powder into the powder returning unit 8; the controller 100 reads the first layer slice data, generates a corresponding scanning command and sends it to the scanning unit 10, controls the scanning unit 10 to perform an energy scanning action, and the metal powder in the scanned area of the powder bed 5 is melted and polymerized, cooled and solidified to generate the first layer of metal deposits and tightly welded to the substrate 51; the controller 100 controls the powder spreading unit 4 to return to the preset position, and the first layer forming process is completed;

[0043] S4: The subsequent forming process is the same as that of the first layer. The controller 100 first issues a descending command to the powder bed 5 and a powder supply command to the powder supply unit 3, performs a unit height descent action and a powder supply action; the controller 100 issues a powder spreading command to the powder spreading unit 4, performs a powder spreading action; the controller 100 reads the single layer slice data, controls the scanning unit 10 to perform an energy scanning action, and the single layer metal deposits generated by the energy scanning are tightly welded to the previous layer of metal deposits; the controller 100 controls the powder spreading unit 4 to return to the preset position; the above steps of the descent of the substrate 51, powder supply, powder spreading, scanning, and the return of the powder spreading unit 4 to the preset position are cyclically executed, and the single layer metal deposits generated are layer by layer welded on the substrate 51 until all the slice layer data of the component are formed, and the generated three-dimensional component is welded on the substrate 51.

[0044] Further, in S3 and S4 of the three-dimensional forming manufacturing method, when the powder spreading unit 4 linearly moves the powder pile 31 forward for powder spreading, the scraping bar first forms a flexible-rigid friction pair with the bottom plate of the forming chamber 2, and then forms a flexible-flexible friction pair with the powder surface of the first pseudo powder bed 6. When the scraping bar enters the powder bed 5 area, the friction pair characteristics of the scraping bar remain stable, thereby ensuring that the powder spreading surface near the edge of the first pseudo powder bed 6 in the powder bed 5 is flat and undisturbed.

[0045] Further, in S3 and S4 of the three-dimensional forming manufacturing method, after the powder spreading unit 4 finishes opening and powder spreading on the powder bed 5 and the scraping bar leaves the powder bed 5 area, it continues to maintain a flexible-flexible friction pair with the powder surface of the second pseudo powder bed 7. When the scraping bar leaves the powder bed 5 area, the friction pair characteristics of the scraping bar remain stable, thereby ensuring that the powder spreading surface near the edge of the second powder bed 5 in the powder bed 5 is flat and undisturbed.

[0046] Further, in S3 and S4 of the three-dimensional forming manufacturing method, when the scanning unit 10 reads and processes the internal slice layer data of the component, it first splits the complete solid surface into nested complementary A and B sub-unit arrays in a rectangular grid pattern, where the A and B sub-unit arrays each account for one-half of the total area. And it completes the forming of the single-layer slice data in the way of first spreading powder and scanning the A sub-unit array, and then spreading powder and scanning the B sub-unit array. The powder bed 5 substrate 51 descends by a unit height that is one-half of the slice data thickness each time. The thickness of the metal deposits formed after the A and B sub-unit arrays are scanned respectively is consistent with the slice data layer thickness. When the scanning unit 10 splits the A and B sub-unit arrays, it merges the corresponding local area of the A sub-unit array on the upper surface area of the current layer slice into the B sub-unit array and applies the upper surface energy scanning parameters to the upper surface area.

[0047] Further, in the mode of splitting layer slice data, in addition to the rectangular grid in the above embodiments, a polygon grid and other free curve grids can also be used.

[0048] Further, in the process of splitting the obtained sub-unit arrays, in addition to A and B each accounting for one-half of the total area in the above embodiments, it can also be that A, B, and C each account for one-third of the total area, or A, B, C, and D each account for one-fourth of the total area, etc. There are more grouping methods. Correspondingly, the powder bed substrate descends by a unit height of one-third and one-fourth of the slice data thickness respectively each time.

[0049] Further, in the scanning mode of the scanning unit for executing the sub-unit arrays, in addition to the first A then B method in the above embodiments, it can also be more grouping sequence scanning methods (such as A->B->C, A->B->C->D, etc.).

[0050] Further, disassemble the nested relationship of the layer-sliced data into sub-unit arrays, including an overlapping area with a settable width, such as 0.1 mm, to ensure reliable connection between sub-array units. The position of the overlapping area between sub-unit arrays can be sequentially offset according to a set pattern, such as a pseudo-random sequence, a zigzag fold-back, etc.

[0051] Further, as Figure 3 , the powder supply unit 3 outputs the powder pile 31 onto the forming chamber bottom plate on the right side of the powder spreading unit 4; the linear module of the powder spreading unit 4 drives the scraper 41 to move forward to the right to perform the powder spreading operation, and the process steps are as follows:

[0052] S1. The scraper 41 first forms a flexible-rigid sliding friction pair with the bottom plate of the forming chamber 2 and has a basic sealing function, so that the powder pile 31 continuously moves in front of the scraper 41;

[0053] S2. The scraper 41 moves forward into the first pseudo powder bed 6, and the scraper 41 forms a flexible-flexible sliding friction pair with the powder surface of the first pseudo powder bed 6. During the transient process of elastic deformation and rebound of the scraper 41, gradually decaying ripple features are generated on the powder surface of the first pseudo powder bed 6;

[0054] S3. The scraper 41 moves forward into the powder bed 5, and the scraper 41 maintains a flexible-flexible sliding friction pair with the powder surface of the powder bed 5. The transient process of elastic deformation and rebound in step S2 ends, and the newly paved single-layer powder state on the surface of the powder bed 5 is flat and uniform;

[0055] S4. When the scraper 41 moves forward through the surface of the large-section metal deposit 200, since the surface morphology of the deposit 200 is a concave-convex grid array, the scattered convex grids prevent the characteristics of the friction pair with the scraper 41 from undergoing a large mutation from the flexible-flexible state. The scattered concave grids play a role of "micro water reservoir" for the newly paved powder, preventing the newly paved powder from being disturbed and accumulated in a large range, so as to generate a flat newly paved single-layer powder on the surface of the metal deposit 200;

[0056] S5. The scraper 41 moves forward into the second pseudo powder bed 7, and the scraper 41 maintains a flexible-flexible sliding friction pair with the powder surface of the second pseudo powder bed 7. The newly paved single-layer powder at the edge of the powder bed 5 and the powder surface of the second pseudo powder bed 7 remain in a flat and stable state;

[0057] S6. The scraper 41 moves forward and leaves the second pseudo powder bed 7, and forms a flexible-rigid sliding friction pair with the bottom plate of the forming chamber 2 again. The scraper 41 pushes the remaining powder of the powder pile 31 into the powder inlet of the powder return unit 8.

[0058] Further, as Figure 4 , if the surface layer of the large-section metal deposit 200 is in the state after the formation of the N-1 layer of sliced data, the formation process of the Nth layer of sliced data is as follows:

[0059] S1, the base plate 51 descends a unit height, the powder supply unit 3 supplies a certain amount of powder required for a single powder spreading to the powder spreading unit 4, and a powder pile 31 is formed on the right side of the scraper 41;

[0060] S2, the powder spreading unit 4 drives the scraper 41 to push the powder pile 31 to perform the powder spreading action, and generates a powder layer 501 on the powder bed 5, wherein the thickness is large at the A subunit array and the thickness is small at the B subunit array;

[0061] S3, the scanning unit 10 performs an A subunit array energy scan of the Nth layer of slice data; the powder spreading unit 4 returns to a preset position;

[0062] S4, repeating step S1, the powder spreading unit 4 drives the scraper 41 to push the powder pile 31 to perform the powder spreading action, and generates a second powder layer 502 on the powder bed 5, wherein the thickness at the B subunit array is large and the thickness at the A subunit array is small;

[0063] S5, the scanning unit 10 performs energy scanning of the B subunit array of the Nth layer of slice data, wherein the upper surface area merged from the A subunit array adopts the upper surface energy scanning parameter; the powder spreading unit 4 returns to the preset position; the Nth layer of slice data is formed;

[0064] S6 , looping through steps S1 - S5 , the metal deposit 200 continuously deposits a new solidified layer until all the slice data of the component layers are read, split, and scanned, and the resulting complete component is welded to the substrate 51 .

[0065] It should be noted that the thickness of the powder layer 1 501 and the powder layer 2 502 are the same, and the added thickness of the two is the thickness of the single-layer slice data.

[0066] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-section metal solid three-dimensional forming system, comprising a frame (1), characterized in that: A forming chamber (2) is fixedly connected to the inner side of the frame (1); a powder supply unit (3) for quantitatively outputting metal powder to the forming chamber (2) is arranged at the top of the forming chamber (2); a powder spreading unit (4) for horizontally spreading powder back and forth on the bottom plate of the forming chamber (2) is arranged on the inner side of the forming chamber (2); a powder bed (5) is arranged on the bottom plate of the forming chamber (2); an opening of the powder bed (5) is embedded in the bottom plate of the forming chamber (2); a first pseudo powder bed (6) is fixedly connected to one end of the bottom plate of the forming chamber (2); and a second pseudo powder bed (7) is fixedly connected to the other end of the bottom plate of the forming chamber (2). The first pseudo powder bed (6) is connected in parallel with one side of the powder bed (5), the second pseudo powder bed (7) is connected in parallel with the other side of the powder bed (5), a powder return unit (8) is provided at one end of the forming chamber (2), a powder inlet of the powder return unit (8) is fixedly connected to the bottom plate of the forming chamber (2), and the powder return unit (8) is located on one side of the second pseudo powder bed (7), an atmosphere unit (9) for filtering and purifying the internal gas of the forming chamber (2) is provided at one end of the inner side of the frame (1), and a scanning unit (10) for scanning the metal powder on the surface of the powder bed (5) is provided at the top of the forming chamber (2); The first pseudo powder bed (6), the powder bed (5) and the second pseudo powder bed (7) are arranged in sequence along the direction from the powder spreading unit (4) to the powder returning unit (8); the powder bed (5) is connected in parallel between the first pseudo powder bed (6) and the second pseudo powder bed (7); the first pseudo powder bed (6), the powder bed (5) and the second pseudo powder bed (7) are connected via powder, so that the powder surfaces of the first pseudo powder bed (6), the powder bed (5) and the second pseudo powder bed (7) respectively form flexible-flexible friction pairs with the scraper, so that the powder spreading surface at the edge of the powder bed (5) is flat and undisturbed.

2. A large-section metal solid three-dimensional forming system according to claim 1, characterized in that: An air inlet (91) is provided at one end of the atmosphere unit (9), and an exhaust port (92) is provided at the other end of the atmosphere unit (9); the air inlet (91) is connected to the gas outlet of the forming chamber (2), and the exhaust port (92) is connected to the gas inlet of the forming chamber (2).

3. A large-section metal solid three-dimensional forming system according to claim 1, characterized in that: The first pseudo powder bed (6) is located between the powder supply unit (3) and the powder bed (5), and the second pseudo powder bed (7) is located between the powder bed (5) and the powder return unit (8).

4. A large-section metal solid three-dimensional forming system according to claim 1, characterized in that: A controller (100) is fixedly connected to the inner side of the frame (1), and the powder supply unit (3), the powder spreading unit (4), the powder bed (5), the atmosphere unit (9), and the scanning unit (10) are all electrically connected to the controller (100).

5. A large-section metal solid three-dimensional forming system according to claim 4, characterized in that: It also includes a three-dimensional forming manufacturing method, which comprises the following steps: S1: Before forming, a sufficient amount of metal powder is first injected into the powder supply unit (3), the forming chamber (2) is closed, and the controller (100) sends an operation instruction to the atmosphere unit (9), and controls the atmosphere unit (9) to adjust the atmosphere environment of the forming chamber (2) to an inert state, thereby maintaining a circulating purification operation; S2: the controller (100) sends a reference point instruction to the powder bed (5), controls the powder bed (5) to drive the substrate (51) to rise to a preset height, the controller (100) sends a reference point instruction to the powder spreading unit (4), controls the powder spreading unit (4) to return to a preset position, the controller (100) sends a pre-powder supply instruction to the powder supply unit (3), controls the powder supply unit (3) to output the metal powder required for pre-powder spreading to the powder spreading unit (4), the controller (100) sends a pre-powder supply instruction to the powder spreading unit (4), controls the linear module of the powder spreading unit (4) to push the powder pile (31) through the first pseudo powder bed (6), the powder bed (5), and the second pseudo powder bed (7) in sequence, so that the powder in the first pseudo powder bed (6) and the second pseudo powder bed (7) is filled to be flush with the bottom plate of the forming chamber (2), the powder spreading unit (4) continues to push the remaining powder in the powder pile (31) into the powder inlet of the powder return unit (8) and then returns to the preset position, and the controller (100) loads the three-dimensional slice data of the part to be formed; S3: When the first layer is formed, the controller (100) first sends a descending instruction to the powder bed (5) and a powder supply instruction to the powder supply unit (3), respectively driving the substrate (51) to descend a unit height and driving the powder supply unit (3) to output the metal powder required for a single powder spreading to the powder spreading unit (4); the controller (100) sends a powder spreading instruction to the powder spreading unit (4), and controls the linear module of the powder spreading unit (4) to perform a powder spreading action, that is, to push the powder pile (31) to fill the depression on the surface of the powder bed (5) generated by the descending of the substrate (51), and push the remaining powder into the powder return unit (8); the controller (100) reads the first layer slice data, generates a corresponding scanning instruction and sends it to the scanning unit (10), controls the scanning unit (10) to perform an energy scanning action, and the metal powder in the scanned area of ​​the powder bed (5) is melted, polymerized, cooled and solidified to generate a first layer of metal deposits and is tightly fused to the substrate (51); the controller (100) controls the powder spreading unit (4) to return to the preset position, and the first layer forming process is completed; S4: The subsequent forming process is the same as the first layer. The controller (100) first sends a descending command to the powder bed (5) and a powder supply command to the powder supply unit (3), and executes a unit height descending action and a powder supply action; the controller (100) sends a powder spreading command to the powder spreading unit (4), and executes a powder spreading action; the controller (100) reads the single-layer slicing data and controls the scanning unit (10) to perform an energy scanning action, and the single-layer metal deposit generated by the energy scanning is tightly fused to the previous layer of metal deposit; the controller (100) controls the powder spreading unit (4) to return to a preset position; the aforementioned substrate (51) descends and the steps of powder supply, powder spreading, scanning, and the powder spreading unit (4) returning to the preset position are executed in a loop, and the generated single-layer metal deposit is fused layer by layer on the substrate (51) until all the slice layer data of the component are formed, and the generated three-dimensional component is fused to the substrate (51).

6. A large-section metal solid three-dimensional forming system according to claim 5, characterized in that: In S3 and S4 of the three-dimensional forming manufacturing method, when the linear module of the powder spreading unit (4) pushes the powder pile (31) forward to spread the powder, the scraper first forms a flexible-rigid friction pair with the bottom plate of the forming chamber (2), and then forms a flexible-flexible friction pair with the powder surface of the first pseudo powder bed (6), so that when the scraper enters the powder bed (5) area, the friction pair characteristics of the scraper remain stable, thereby ensuring that the powder spreading surface of the powder bed (5) near the edge of the first pseudo powder bed (6) is flat and undisturbed.

7. A large-section metal solid three-dimensional forming system according to claim 6, characterized in that: In S3 and S4 of the three-dimensional forming manufacturing method, after the powder spreading unit (4) has completed the powder spreading of the powder bed (5) opening and the scraper bar has left the powder bed (5) area, it continues to maintain a flexible-flexible friction pair with the powder surface of the second pseudo powder bed (7), so that when the scraper bar leaves the powder bed (5) area, the scraper bar friction pair characteristics remain stable, thereby ensuring that the powder spreading surface of the powder bed (5) near the edge of the second powder bed (7) is flat and undisturbed.

8. A large-section metal solid three-dimensional forming system according to claim 7, characterized in that: In S3 and S4 of the three-dimensional forming manufacturing method, the typical powder depth of the first pseudo powder bed (6) and the second pseudo powder bed (7) is 1 mm to 5 mm, and the typical width is 10 mm to 30 mm. It is only necessary to fill the metal powder to the same height as the bottom plate of the forming chamber (2) in the pre-powdering step, and no additional metal powder consumption is generated during the layer-by-layer forming process.

9. A large-section metal solid three-dimensional forming system according to claim 5, characterized in that: In S3 and S4 of the three-dimensional forming manufacturing method, when reading and processing the slice layer data inside the component, the scanning unit (10) first splits the complete solid surface into nested complementary A and B sub-unit arrays in a rectangular grid pattern, wherein the A and B sub-unit arrays each occupy half of the total area, and completes the single-layer slice data forming in a manner of first spreading powder and scanning the A sub-unit array, and then spreading powder and scanning the B sub-unit array. The unit height of the base plate (51) of the powder bed (5) is lowered each time by half of the slice data thickness. The thickness of the metal deposit after scanning the A and B sub-unit arrays is consistent with the slice data layer thickness.

10. A large-section metal solid three-dimensional forming system according to claim 9, characterized in that The scanning method of the A and B subunit arrays is as follows: S1, the base plate (51) descends a unit height, the powder supply unit (3) supplies a quantitative amount of powder required for a single powder spreading to the powder spreading unit (4), and a powder pile (31) is formed on the right side of the scraper (41); S2, the powder spreading unit (4) drives the scraper (41) to push the powder pile (31) to perform a powder spreading action, thereby generating a powder layer 1 (501) on the powder bed (5), wherein the thickness of the A subunit array is large and the thickness of the B subunit array is small; S3, the scanning unit (10) performs an A sub-unit array energy scan of the Nth layer of slice data; the powder spreading unit (4) returns to a preset position; S4, repeatedly executing the scanning method S1, the powder spreading unit (4) drives the scraper (41) to push the powder pile (31) to perform a powder spreading action, and generates a second powder layer (502) on the powder bed (5), wherein the thickness at the B subunit array is large and the thickness at the A subunit array is small; S5, the scanning unit (10) performs energy scanning of the B subunit array of the Nth layer of slice data, wherein the upper surface area merged from the A subunit array adopts the upper surface energy scanning parameters; the powder spreading unit (4) returns to the preset position; and the Nth layer of slice data is formed.

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