Large-section metal entity three-dimensional forming system

Abstract

The invention relates to the technical field of metal entity three-dimensional forming, and provides a large-section metal entity three-dimensional forming system which comprises a frame, a forming chamber is fixedly connected to the inner side of the frame, a powder supply unit is arranged at the top end of the forming chamber, a powder laying unit is arranged on the inner side of the forming chamber, and a powder bed is arranged on a bottom plate of the forming chamber. One end of a bottom plate of the forming chamber is fixedly connected with a first pseudo powder bed, the other end of the bottom plate of the forming chamber is fixedly connected with a second pseudo powder bed, one end of the forming chamber is provided with a powder return unit, a powder inlet of the powder return unit is fixedly connected with the bottom plate of the forming chamber, one end of the inner side of the frame is provided with an atmosphere unit, and the top end of the forming chamber is provided with a scanning unit. The method is easy and convenient to implement, small in powder spreading disturbance, smooth and uniform in single-layer powder on the surface of the powder bed, high in forming precision, good in strength and easy to apply and popularize in various high-precision and medium-and-large-size laser and electron beam metal powder bed three-dimensional forming equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of metal solid three-dimensional forming, and in particular to a large-section metal solid three-dimensional forming system. Background Art

[0002] Laser and electron beam metal powder bed forming technology is one of the main methods in the field of additive manufacturing. It is based on laying metal powder layer by layer on the forming cylinder substrate, scanning the selected area of ​​the powder bed with laser and electron beam to make it melt, polymerize, cool and solidify, and deposit on the substrate. Then, through the repeated execution of the substrate layer by layer, powder laying and scanning steps, the deposit grows layer by layer on the substrate until the whole is fully formed. Since the metal powder in the unscanned area fills the redundant space of the forming cylinder well, the layer-by-layer growth process of the deposit 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 have outstanding advantages in the forming of precision and complex metal structural parts. Existing metal powder bed forming equipment mainly includes SLM (selective laser melting) equipment and EBM (electron beam melting) equipment, among which SLM is mainly used for the three-dimensional forming of conventional metal powder materials, and EBM is mainly used for the three-dimensional forming of refractory metal powder materials; It is easy to infer that laying metal powder with uniform and controllable thickness layer by layer on the powder bed is the primary prerequisite for accurately generating a single layer of metal deposits. Abnormal powder 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. Existing powder spreading devices generally use linear modules to drive scrapers to push the powder pile forward, and adjust the powder thickness by the gap between the scraper and the surface of the powder bed. To this end, the normal powder spreading state must rely on the following conditions: First, the powder fluidity is good to ensure that the thin layer of powder does not crack when the scraper pushes the powder pile forward; second, the viscosity between the powder pile and the surface of the powder bed 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 the necessary rigidity and self-lubricating properties to avoid friction with the bottom plate of the forming chamber and the surface of the powder bed to cause creeping and shaking.

[0003] In a practical environment, the above conditions are difficult to fully meet. For example, the metal deposit area and the powder area on the surface of the powder bed have obvious differences in their viscosity to the powder pile; when the metal deposit area is large, powder displacement and uneven distribution will occur when spreading powder on its surface. In addition, during the powder spreading process, the linear module must drive the scraper through multiple functional areas such as powder supply, powder bed, and powder return. The pair elements of the scraper friction pair switch multiple times between the metal plate, powder surface, and metal deposit surface, which will cause a sudden change in the characteristics of the friction pair, and then cause ripples on the powder surface. Uneven powder distribution and ripples on the powder surface will directly interfere with the accuracy of the scanning energy strategy of the laser and electron beam, and leave obvious defect features on the formed metal parts, thereby limiting the development potential of SLM and EBM equipment to manufacture large-size, large-cross-section precision and complex metal parts. Problems such as difficulty in spreading powder with 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 industry, and there is no effective technical solution. There are reports that based on changing the forming posture, the vertical projection area of ​​large cross-section parts, i.e. the slicing area, is reduced by tilting the placement, but this will greatly increase the number of forming layers and process risks. At present, 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 precise and reliable manufacturing of large-section metal solid parts. In view of this, the present invention proposes a large-section metal solid three-dimensional forming system. Summary of the invention

[0004] The present invention provides a large-section metal solid three-dimensional forming system, which solves the problems in the prior art of difficulty in powder spreading of large cross-sections, large scanning thermal stress, poor forming accuracy and low success rate.

[0005] The technical solution of the present invention is as follows: A large-section metal solid three-dimensional forming system comprises a frame, a forming chamber is fixedly connected to the inner side of the frame, a powder supply unit for quantitatively outputting metal powder to the forming chamber is arranged at the top of the forming chamber, a powder spreading unit for horizontally spreading powder back and forth on the bottom plate of the forming chamber is arranged on the inner side of the forming chamber, a powder bed is arranged on the bottom plate of the forming chamber, the opening of the powder bed is embedded in 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, a second pseudo-powder bed is fixedly connected to the other end of the bottom plate of the forming chamber, 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, a powder return unit is arranged at one end of the forming chamber, a powder inlet of the powder return unit is fixedly connected to the bottom plate of the forming chamber, and the powder return unit is located on one side of the second pseudo-powder bed, an atmosphere unit for filtering and purifying the gas inside the forming chamber is arranged at one end of the inner side of the frame, and a scanning unit for scanning the metal powder on the surface of the powder bed is arranged at the top of the forming chamber.

[0006] Preferably, an air inlet is provided at one end of the atmosphere unit, and an exhaust port is provided at the other end of the atmosphere unit, the air inlet is connected to the gas outlet of the forming chamber, and the exhaust port is connected to the gas inlet of the forming chamber.

[0007] 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.

[0008] Preferably, a controller is fixedly connected to the inner side of the frame, and the powder supply unit, powder spreading unit, powder bed, atmosphere unit and scanning unit are all electrically connected to the controller.

[0009] Preferably, a large-section metal solid three-dimensional forming system also includes a three-dimensional forming manufacturing method, which specifically comprises the following steps: S1: Before forming, first inject sufficient metal powder into the powder supply unit, close the forming chamber, and the controller sends an operation command to the atmosphere unit to control the atmosphere unit to adjust the atmosphere environment of the forming chamber to an inert state, thereby maintaining the circulation purification operation; S2: The controller sends a reference point command to the powder bed, controls the powder bed driving substrate to rise to a preset height, sends a reference point command to the powder spreading unit, controls the powder spreading unit to return to a preset position, sends a pre-powder supply command to the powder supply unit, controls the powder supply unit to output the metal powder required for pre-powder spreading to the powder spreading unit, sends a pre-powder supply command to the powder spreading unit, controls the linear module of the powder spreading unit to push the powder pile through the first pseudo powder bed, the powder bed, and the second pseudo powder bed in sequence, 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, and the powder spreading unit continues to push the remaining powder in the powder pile into the powder inlet of the powder return unit and then returns to the preset position, and the controller loads the three-dimensional slicing data of the part to be formed; S3: When the first layer is formed, the controller first sends a descending command to the powder bed and a powder supply command to the powder supply unit, respectively driving the substrate to descend a unit height and driving the powder supply unit to output the metal powder required for a single powder spreading to the powder spreading unit; the controller sends a powder spreading command to the powder spreading unit, and controls the linear module of the powder spreading unit to perform the powder spreading action, that is, to push the powder pile to fill the depression on the surface of the powder bed caused by the descending substrate, and push the remaining powder into the powder return unit; the controller reads the first layer slicing data, generates the corresponding scanning command and sends it to the scanning unit, controls the scanning unit to perform the energy scanning action, and the metal powder in the scanned area of ​​the powder bed is melted, polymerized, cooled and solidified to form the first layer of metal deposits and tightly fused to the substrate; the controller controls the powder spreading unit 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 first sends a descending command to the powder bed and a powder supply command to the powder supply unit to execute the unit height descending action and the powder supply action; the controller sends a powder spreading command to the powder spreading unit to execute the powder spreading action; the controller reads the single-layer slicing data and controls the scanning unit to execute the energy scanning action. The single-layer metal deposit generated by the energy scanning is tightly fused to the previous layer of metal deposit; the controller controls the powder spreading unit to return to the preset position; the aforementioned steps of substrate descending and powder supply, powder spreading, scanning, and the powder spreading unit 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 until all the slice layer data of the component are formed, and the generated three-dimensional component is fused to the substrate.

[0010] 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 scraper 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 scraper bar enters the powder bed area, the friction pair characteristics of the scraper bar remain stable, thereby ensuring that the powder spreading surface of the powder bed near the edge of the first pseudo powder bed is flat and undisturbed.

[0011] Preferably, in S3 and S4 of the three-dimensional forming manufacturing method, after the powder spreading unit completes spreading the powder on the powder bed opening and the scraper strip 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 scraper strip leaves the powder bed area, the friction pair characteristics of the scraper strip remain stable, thereby ensuring that the powder spreading surface of the powder bed near the edge of the second powder bed is flat and undisturbed.

[0012] 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 1mm-5mm, and the typical width is 10mm-30mm. It is only necessary to fill the metal powder to the same height as the bottom plate of the forming chamber in the pre-powdering step, and no additional metal powder consumption is generated during the layer-by-layer forming process.

[0013] Preferably, in S3 and S4 of the three-dimensional forming manufacturing method, when reading and processing the internal slice layer data of the component, the scanning unit first splits the complete solid surface into nested and 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 by 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 powder bed substrate descends each time is half of the slice data thickness, and the thickness of the metal deposits scanned and formed by the A and B sub-unit arrays are consistent with the slice data layer thickness.

[0014] Preferably, the scanning method of the A and B subunit arrays is as follows: S1, the substrate descends to a unit height, the powder supply unit supplies a certain amount of powder required for a single powder spreading to the powder spreading unit, and a powder pile is formed on the right side of the scraper; S2, the powder spreading unit drives the scraper to push the powder pile to perform the powder spreading action, and generates a powder layer 1 on the powder bed, wherein the thickness is large at the A subunit array and the thickness is small at the B subunit array; S3, the scanning unit performs an A subunit array energy scan of the Nth layer of slice data; the powder spreading unit returns to the preset position; S4, repeatedly executing the scanning method S1, the powder spreading unit drives the scraper to push the powder pile to perform the powder spreading action, and generates a second powder layer on the powder bed, wherein the thickness at the B subunit array is large and the thickness at the A subunit array is small; S5. The scanning unit 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 returns to the preset position; and the Nth layer of slice data is formed.

[0015] The working principle and beneficial effects of the present invention are: 1. The present invention eliminates the sudden disturbance of the friction parameters of the scraper bar when the scraper bar of the powder spreading unit enters and leaves the powder bed through the first pseudo powder bed and the second pseudo powder bed, and splits the large-section slice layer data into mutually nested sub-unit arrays, and spreads powder twice and scans separately to solve the problem of difficulty in spreading powder on the large-section metal deposit, thereby ensuring the powder spreading accuracy of the powder bed and the accuracy of the generated single-layer metal deposit; 2. The present invention splits the large-section layer slice data into mutually nested sub-unit arrays and performs two powder-laying alternating scans, which also has the function of dispersing energy to scan thermal stress and form an interlayer nested structure, which has a positive effect on reducing thermal stress deformation and improving interlayer strength; 3. The scheme of the present invention is easy to implement, with small powder spreading disturbance, a flat and uniform single layer of powder on the surface of the powder bed, high forming accuracy and good strength, and is easy to promote and apply in various high-precision, medium and large-sized laser and electron beam metal powder bed three-dimensional forming equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0017] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 is a control signal connection diagram of an embodiment of the present invention; Figure 3 This is a schematic diagram of the powder spreading action of an embodiment of the present invention; Figure 4 It is a schematic diagram of layer-by-layer energy scanning forming according to an embodiment of the present invention.

[0018] 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. powder layer one; 502. powder layer two; 6. first pseudo powder bed; 7. second pseudo powder bed; 8. powder return unit; 9. atmosphere unit; 91. air inlet; 92. exhaust port; 10. scanning unit; 100. controller; 200. large-section metal deposit. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1-2 As shown, this embodiment proposes a large-section metal solid three-dimensional forming system, including a frame 1, 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 reciprocating powder spreading 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, the opening of the powder bed 5 is embedded in the bottom plate of the forming chamber 2, one end of the bottom plate of the forming chamber 2 is fixedly connected to a first pseudo-powder bed 6, the other end of the bottom plate of the forming chamber 2 is fixedly connected to a second pseudo-powder bed 7, 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, and the forming chamber 2 is provided with a powder bed 5. A powder return unit 8 is provided at one end, the first pseudo powder bed 6 is located between the powder supply unit 3 and the powder bed 5, the second pseudo powder bed 7 is located between the powder bed 5 and the powder return unit 8, the 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, and 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, 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, 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.

[0021] A controller 100 is fixedly connected to the inner side of the frame 1. 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. The controller 100 sends an electrical signal to the powder supply unit 3 to control the powder supply unit 3 to output the quantitative metal powder required for spreading to the powder spreading unit 4; the controller 100 sends an electrical signal to the powder spreading unit 4 to control the linear module of the powder spreading unit 4 to drive the scraper to perform the powder spreading action from left to right and to perform the return 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 the component is formed, and then to descend a unit height before spreading the powder 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 circulation 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 the selected area on the surface of the powder bed 5 according to the set power, speed, focusing diameter and other parameters.

[0022] The first pseudo powder bed 6 and the second pseudo powder bed 7 are used to eliminate the sudden disturbance of the friction parameters of the scraper of the powder spreading unit 6 when the scraper enters and leaves the powder bed 5, and the large-section slice layer data is split into mutually nested sub-unit arrays, and powder is spread twice and scanned separately to solve the problem of difficulty in spreading powder on the large-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-section layer slice data into mutually nested sub-unit arrays and scanning the powder twice alternately, it also has the function of dispersing energy to scan thermal stress and forming an interlayer nested structure, which has a positive effect on reducing thermal stress deformation and improving interlayer strength.

[0023] The present invention also provides a large-section metal solid three-dimensional forming manufacturing method, comprising the following steps: S1: Before forming, first inject sufficient metal powder into the powder supply unit 3, close the forming chamber 2, and the controller 100 sends an operation instruction to the atmosphere unit 9 to control 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 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 sends a reference point command to the powder spreading unit 4, controls the powder spreading unit 4 to return to the preset position, the controller 100 sends 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 sends a pre-powder supply command to the powder spreading unit 4, controls the linear module of the powder spreading unit 4 to push the powder pile 31 to pass 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, wherein the typical powder depth of the first pseudo powder bed 6 and the second pseudo powder bed 7 is 1mm-5mm, and the typical width is 10mm-30mm, and it is only necessary to fill the metal powder 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 is generated during the layer-by-layer forming process, and the powder spreading unit 4 continues to push the remaining powder of 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 command to the powder bed 5 and a powder supply command 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 command to the powder spreading unit 4, and controls the linear module of the powder spreading unit 4 to perform the powder spreading action, that is, pushes the powder pile 31 to fill the depression on the surface of the powder bed 5 generated by the descent of the substrate 51, and pushes the remaining powder into the powder return unit 8; the controller 100 reads the first layer slicing 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, polymerized, cooled and solidified to form the first layer of metal deposits and 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 the unit height descending action and the powder supply action; the controller 100 sends a powder spreading command to the powder spreading unit 4 and executes the powder spreading action; the controller 100 reads the single-layer slicing data and controls the scanning unit 10 to perform the energy scanning action. 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 the preset position; the aforementioned substrate 51 descends and the steps of powder supply, powder spreading, scanning, and the powder spreading unit 4 returns 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.

[0024] Furthermore, 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 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, so that when the scraper bar enters the powder bed 5 area, the friction pair characteristics of the scraper bar 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.

[0025] Furthermore, in S3 and S4 of the three-dimensional forming manufacturing method, after the powder spreading unit 4 completes spreading the powder on the opening of the powder bed 5 and the scraper strip 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, so that when the scraper strip leaves the powder bed 5 area, the friction pair characteristics of the scraper strip remain stable, thereby ensuring that the powder spreading surface of the powder bed 5 near the edge of the second powder bed 5 is flat and undisturbed.

[0026] Furthermore, in S3 and S4 of the three-dimensional forming manufacturing method, when reading and processing the internal slice layer data of 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 by 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 powder bed 5 substrate 51 descends each time is half of the slice data thickness. The thickness of the metal deposit formed after the A and B sub-unit arrays are scanned separately is consistent with the slice data layer thickness. When splitting the A and B sub-unit arrays, the scanning unit 10 merges the A sub-unit array part corresponding to the upper surface area of ​​the current layer of slices with the B sub-unit array and applies the upper surface energy scanning parameters to the upper surface area.

[0027] Furthermore, in the mode of splitting layer slice data, in addition to the rectangular grid in the above embodiment, polygonal grids and other free curve grids can also be used.

[0028] Furthermore, in the process of splitting the obtained sub-unit array, in addition to the above embodiment in which A and B each occupy half of the total area, there may also be more grouping methods such as A, B, and C each occupy one-third of the total area, or A, B, C, and D each occupy one-quarter of the total area. Correspondingly, the unit height of the powder bed substrate descends each time by one-third or one-quarter of the slice data thickness, respectively.

[0029] Furthermore, in the scanning mode of the scanning unit executing the sub-unit array, in addition to the A-first-B-later method in the above embodiment, more grouped sequential scanning methods (such as A->B->C, A->B->C->D, etc.) can also be used.

[0030] Furthermore, the nested relationship of the split layer slice data to the sub-unit array includes an overlap area with a settable width, such as 0.1 mm, to ensure reliable connection between sub-array units. The overlap area positions between sub-unit arrays can be shifted successively according to a set rule, such as a pseudo-random sequence, zigzag retracement, etc.

[0031] Furthermore, if Figure 3 The powder supply unit 3 outputs the powder pile 31 to the bottom plate of the forming chamber 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 rightward to perform the powder spreading action. The process steps are as follows: S1, the scraper 41 first forms a soft-rigid sliding friction pair with the bottom plate of the forming chamber 2, and has a basic sealing effect, so that the powder pile 31 continues to move in front of the scraper 41; S2, the scraper 41 moves forward into the first pseudo powder bed 6, the scraper 41 and the powder surface of the first pseudo powder bed 6 form a soft-soft sliding friction pair, and the elastic deformation and rebound transient process of the scraper 41 generates a gradually decaying ripple feature on the powder surface of the first pseudo powder bed 6; S3, the scraper 41 moves forward into the powder bed 5, and the scraper 41 and the powder surface of the powder bed 5 maintain a soft-soft sliding friction pair, and the elastic deformation rebound transient process of step S2 ends, and the surface of the powder bed 5 is newly covered with a single layer of powder in a flat and uniform state; 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 dispersed convex grids prevent the friction pair characteristics with the scraper 41 from changing greatly from a soft-soft state, and the dispersed concave grids act as a "micro-reservoir" for the newly laid powder, preventing the newly laid powder from being disturbed and accumulated in a large range, thereby generating a flat newly laid single layer of powder on the surface of the metal deposit 200; S5, the scraper 41 moves forward into the second pseudo powder bed 7, the scraper 41 and the powder surface of the second pseudo powder bed 7 maintain a soft-soft sliding friction pair, and the newly laid single layer of powder at the edge of the powder bed 5 and the powder surface of the second pseudo powder bed 7 remain flat and stable; S6, the scraper 41 moves forward and leaves the second pseudo powder bed 7, and forms a soft-rigid sliding friction pair with the bottom plate of the forming chamber 2 again, and the scraper 41 pushes the remaining powder in the powder pile 31 to fall into the powder inlet of the powder return unit 8.

[0032] Furthermore, if Figure 4 , the surface layer of the large-section metal deposit 200 is in the state after the N-1 layer of slice data is formed, and the Nth layer of slice data forming process is as follows: 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; 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; 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; 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; 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; 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 .

[0033] 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.

[0034] 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), and 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), and 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).

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 (5) 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 is large at the B subunit array and the thickness is small at the A subunit array; 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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