A dual-substrate mode laser selective melting additive manufacturing apparatus and method

Abstract

This invention discloses a dual-substrate mode laser selective melting additive manufacturing apparatus and method. The dual substrates are independently driven, and the Z-axis motion of the substrates is controlled to achieve printing of different layer thicknesses within the same layer. The apparatus consists of dual substrates, a forming cylinder motion mechanism, and an independent drive mechanism for the dual substrates. The dual substrates can be arranged concentrically or in parallel. For a concentric arrangement, the drive screw of the first substrate is solid, and the drive screw of the second substrate is hollow, with both types of screws coaxial. For a parallel arrangement, both substrates have solid drive screws, arranged in a front-to-back or left-to-right parallel configuration. The method describes the process flow, part distribution, and relative motion constraints of the dual substrates for printing with the same and different layer thicknesses, ensuring the realization of the dual-substrate mode SLM additive manufacturing process. This invention enables SLM additive printing of different layer thicknesses within the same layer, reduces support structures, thereby saving powder consumption, improving forming efficiency, and reducing production costs.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing, specifically relating to a dual-substrate mode laser selective melting additive manufacturing apparatus and method. Background Technology

[0002] Selective laser melting (SLM) is currently the metal additive manufacturing technology with the highest forming precision and the most complex formed structures, and it is widely used in aerospace, nuclear power, and other fields. However, SLM additive manufacturing technology is subject to inherent process constraints such as forming angle, overhang width, and powder layer thickness. For example, in the unsupported additive manufacturing mode, the forming angle needs to be greater than 45°, the overhang width is less than 3mm, and the powder layer thickness is generally less than 0.1mm, resulting in low forming efficiency and high manufacturing cost. Existing related patents and literature report that improving the forming efficiency of SLM additive manufacturing is mainly achieved through multi-laser collaboration, large layer thickness, fewer supports, and beam shaping. Existing SLM additive manufacturing equipment is all single-substrate mode, which can achieve different layer thicknesses in different height areas of the same part, but cannot print different layer thicknesses on the same cross-section.

[0003] Especially for flange-like components with flanges at both ends or flange-like components that are closed at one end and flanged at the other, achieving unsupported lower surface of the flange would effectively improve SLM forming efficiency. For additive manufacturing of different parts within the same compartment, simultaneously forming different layer thicknesses within the same compartment would also effectively improve SLM forming efficiency. For medium to large-sized SLM additive manufacturing equipment, the large initial powder demand and high start-up costs are detrimental to the low-cost development of new products and structures. Therefore, addressing the problems of low forming efficiency, the limitation of printing parts with the same layer thickness within the same compartment, and the large initial powder demand in existing SLM additive manufacturing methods, it is urgent to develop SLM additive manufacturing methods with different layer thicknesses within the same layer. This would break through the limitation of existing single-substrate SLM additive manufacturing equipment that can only have one physical layer thickness in the same layer, enabling the printing of multiple layer thicknesses within the same layer.

[0004] Patent CN202411198622.X reports an SLM additive manufacturing device and method, which divides a single forming cylinder into multiple circumferentially distributed small forming cylinders. A rotating mechanism drives the multiple forming cylinders to pass sequentially under a powder spreading mechanism and a laser assembly. Based on the principle of saving powder spreading time per cycle and synchronizing powder spreading with laser sintering, it achieves improved SLM additive manufacturing efficiency and powder conservation. However, the multiple forming cylinders still use the same layer thickness for printing, which cannot solve the problem of printing multiple layer thicknesses in the same chamber or different layer thicknesses in the same layer; for components with flanges at the top and bottom or components with one end closed and the other end with a flange, it cannot achieve near-unsupported forming.

[0005] Patent CN202510042836.6 reports a laser scanning device, additive manufacturing equipment, and method based on spot switching. By switching spots, a Gaussian spot prints the outer contour of the workpiece, while a large annular spot prints the filling area. Several layers of the outer contour are printed first, followed by a single-pass printing of the filling area, effectively improving the efficiency of SLM additive manufacturing. However, adjusting the emission interval between the annular and Gaussian spots still cannot achieve printing different layer thicknesses for different parts within the same compartment. Near-unsupported forming cannot be achieved for components with flanges at both ends or components with one closed end and one flanged end; furthermore, the forming area remains unchanged, and the initial powder requirement is not significantly reduced. Additionally, the transition or overlap areas between the contour and the filling are prone to metallurgical defects such as porosity and cracking due to excessively high laser energy from the large annular spot. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a dual-substrate mode laser selective melting additive manufacturing apparatus and method. By adjusting the physical drop of each layer of the two substrates, the limitation of existing single-substrate SLM additive manufacturing equipment that can only have one physical layer thickness in the same layer is overcome, enabling printing of different layer thicknesses in the same layer. For parts requiring support structures, especially flange-like components with flanges at the top and bottom or flange-like components with one closed end and one flanged end, the flange (suspended structure) and frame of the part are spatially arranged on two substrates. By raising the substrate where the flange is located in a timely manner, the lower surface of the flange can be directly laser-sintered onto the substrate, achieving near-supportless forming of this type of flange feature and improving the efficiency of SLM additive manufacturing. For additive manufacturing of different parts in the same compartment, the parts are classified and arranged on two substrates according to the printing layer thickness. The descent of each layer of the two substrates is adjusted independently to achieve different layer thicknesses for different parts in the same compartment. For medium and large-sized SLM additive manufacturing equipment, which has a large demand for powder in the first compartment and high development cost for printing small-format parts, the target part is arranged on one substrate, and the lifting and lowering of the other substrate is adjusted to save powder filling in that area. Combined with dynamic powder spreading technology in the same layer, this can effectively improve the efficiency of SLM additive manufacturing and save the development cost of the first part.

[0007] To achieve the above objectives, the present invention employs the following technical solutions: A dual-substrate mode laser selective melting additive manufacturing apparatus includes a forming cylinder, a first substrate, a second substrate, a first substrate driving mechanism, and a second substrate driving mechanism. Both the first substrate and the second substrate are placed inside the forming cylinder, forming a dual-substrate configuration. The two substrates are arranged concentrically (concentric circles, concentric rectangles) or side-by-side (front-to-back, left-to-right), with a horizontal gap of 1mm to 3mm between them. A high-temperature resistant elastic sealing cloth is designed on the lower surface of this horizontal gap to collect powder from the gap between the two substrates. The first substrate and the second substrate are respectively connected to a first substrate driving mechanism and a second substrate driving mechanism. The first substrate driving mechanism and the second substrate driving mechanism are used to drive the corresponding substrates to move independently along the Z-axis, enabling the dual substrates to move synchronously or asynchronously within the forming cylinder. The descent amount of the first substrate and the second substrate after single-layer sintering can be set separately.

[0008] Furthermore, both the first substrate driving mechanism and the second substrate driving mechanism include a servo motor, a gear pair, and a lead screw and nut pair that are connected in sequence; when the first substrate and the second substrate are concentrically distributed, the lead screw of the first substrate driving mechanism is a solid lead screw, and the lead screw of the second substrate driving mechanism is a hollow lead screw, with the two types of lead screws arranged coaxially and nested; when the first substrate and the second substrate are arranged side by side, the lead screws of both the first substrate driving mechanism and the second substrate driving mechanism are solid lead screws, which are arranged parallel to each other and have the same length.

[0009] Furthermore, the first substrate and the second substrate are respectively fixedly connected to the lead screw adapter flange of the corresponding drive mechanism through independent heater integration boxes; sealing gaskets are respectively provided between the two types of substrates and the corresponding heater integration boxes; the outer peripheral horizontal gap between the outer side of the substrate and the inner wall of the forming cylinder is 3mm to 10mm.

[0010] Furthermore, the first substrate driving mechanism and the second substrate driving mechanism each include several sets of guide rod assemblies, preferably four sets in this embodiment, for guiding and supporting the Z-axis movement of each substrate.

[0011] Furthermore, the forming cylinder includes a cylinder body and a base that are fixedly connected; a support slide is provided at the lower end of the base, and a forming cylinder drive mechanism is installed between the support slide and the base. The forming cylinder drive mechanism includes a servo electric cylinder, a guide rod, and a locking flange to realize the Z-axis movement of the forming cylinder; a horizontal guide rail is provided at the lower end of the support slide, and the support slide can slide along the horizontal guide rail to realize the movement and switching of the entire device between the printing chamber, the powder cleaning chamber, and the part picking chamber.

[0012] A dual-substrate mode laser selective melting additive manufacturing method includes the following steps: S1: According to the process layout requirements of the parts to be manufactured, arrange the parts to be manufactured on the first substrate and / or the second substrate, and determine the powder layer thickness Δ1 of the first substrate and the powder layer thickness Δ2 of the second substrate, and Δ1≤Δ2; S2: Set the SLM additive manufacturing process parameters according to the powder layer thickness of the corresponding parts on each substrate; S3: Level the first substrate and the second substrate so that their upper surfaces are on the same horizontal plane, and then apply powder. S4: Perform laser sintering according to the slicing scanning path of the corresponding area of ​​the first substrate and / or the corresponding area of ​​the second substrate; S5: After the single-layer sintering is completed, the first substrate is lowered by Δ1 and / or the second substrate is lowered by Δ2; S6: Repeat the powder spreading, laser sintering and substrate lowering steps until the part to be manufactured is printed; Furthermore, the process layout requirements include, but are not limited to, one or more of the following conditions: whether the optional powder layer thickness of the components to be manufactured is different, whether the components to be manufactured need to be provided with a support structure, and whether the maximum horizontal projection cross section of any part spans the two substrates.

[0013] Furthermore, when the optional powder layer thickness of the components to be manufactured is different and the maximum horizontal projected cross section of any part does not span the two substrates, In step S1, the thin-layer component is arranged on the first substrate, and the thick-layer component is arranged on the second substrate. In step S4, laser sintering is performed according to the slicing scanning path of the corresponding area of ​​the first substrate and the corresponding area of ​​the second substrate; In step S5, the first substrate descends by Δ1, and the second substrate descends by Δ2; In step S6, when the printing of a part on one substrate is completed and the printing of a part on another substrate still needs to continue, the substrate that has completed printing can choose to stop descending or continue descending according to the set descent amount.

[0014] This method is particularly suitable for manufacturing multiple parts with different layer thicknesses in the same layer, and can effectively improve the part forming efficiency.

[0015] Furthermore, for components requiring support structures, such as those with flanges at both ends or those closed at one end and with flanges at the other, a concentrically distributed dual-substrate SLM additive manufacturing mode is adopted. In step S1, the component frame structure is arranged on the first substrate, and the suspended structure that needs to be supported and extends beyond the first substrate is arranged on the second substrate. In steps S4 to S6, before the first layer appears on the lower surface of the overhanging structure, the second substrate remains in its initial flush position, and the first substrate descends layer by layer according to the set layer thickness and laser-sintersects the structural frame structure; when the first layer appears on the lower surface of the overhanging structure, the powder is laser-sintered and the overhanging structure forms a metallurgical bond with the upper surface of the second substrate; then the first substrate and the second substrate descend synchronously with the same layer thickness until the printing is completed.

[0016] This method is particularly suitable for manufacturing parts that require support structures. It can reduce the design and printing time of support mechanisms during the manufacturing process. Especially for flange-like components with flanges at the top and bottom or flange-like components with one end closed and the other end flanged, it can achieve near-supportless forming, which not only saves the production cost of parts, but also improves the forming efficiency of parts.

[0017] Furthermore, when the maximum width of the horizontal projection of the component to be manufactured is less than the width of either the first substrate or the second substrate, In step S1, the target component is arranged on only one of the first substrate or the second substrate, and the other substrate is an empty substrate. In step S4, laser sintering is performed only on the slice scanning path of the substrate containing the parts; In step S5, the substrate containing only the component is lowered by the corresponding layer thickness, while the other substrate remains stationary.

[0018] This method is particularly suitable for large-scale SLM additive manufacturing equipment to manufacture the first piece of small-format parts, which can effectively avoid powder waste and reduce development costs.

[0019] The present invention has the following advantages: I. This invention transforms the existing single-substrate mode into a dual-substrate independent driving mode, directly adjusting the physical drop of each layer of the two substrates, breaking through the limitation of existing single-substrate SLM additive manufacturing equipment that can only have one physical layer thickness in the same layer, and realizing printing of different layer thicknesses in the same layer. Second, the two substrates of this invention can move independently or relative to each other. The physical descent of each layer of each substrate does not affect each other. It can meet the requirement of forming different parts of the same compartment with large and small layer thicknesses at the same time, and realize the function of forming two layer thickness parameter packages at the same time on the same SLM additive manufacturing equipment. Third, for components that require a support structure, adjusting the layout of the corresponding suspension structure and the relative movement of the double base plate can reduce the need for a support structure for the suspension structure. In particular, for flange-type components with flanges at the top and bottom or flange-type components with one end closed and the other end flanged, near-supportless forming can be achieved, greatly improving forming efficiency. Fourth, for medium and large-sized SLM additive manufacturing equipment, which has a large demand for powder in the first batch of small-format parts and high development costs, the target part is placed on one substrate, and the lifting amount of another substrate is adjusted to save powder filling in that area. Combined with dynamic powder spreading technology on the same layer, the efficiency of SLM additive forming can be effectively improved and the development cost of the first part can be saved. Attached Figure Description

[0020] Figure 1 This is a perspective view (concentric type) of a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0021] Figure 2 This is a top view (concentric type) of a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0022] Figure 3 This is a cross-sectional schematic diagram (concentric type) of the first drive mechanism of a dual-substrate mode laser selective melting additive manufacturing apparatus. Figure 4 This is a cross-sectional schematic diagram (concentric type) of the second drive mechanism of a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0023] Figure 5 This is a cross-sectional schematic diagram (concentric type) of the forming cylinder drive mechanism of a dual-substrate mode laser selective melting additive manufacturing device.

[0024] Figure 6 A schematic diagram of the sealing between the two substrates (concentric type) of a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0025] Figure 7 A schematic diagram of the highest and lowest points (concentric) of a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0026] Figure 8 A simplified diagram of the concentrically distributed dual substrates in a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0027] Figure 9 A simplified diagram of the parallel-distributed dual-substrate mode motion of a dual-substrate mode laser selective melting additive manufacturing apparatus.

[0028] Figure 10 This is a schematic diagram of the structural features of a flange-type component with flanges at both the top and bottom.

[0029] Figure 11 This is a schematic diagram of the structural features of a flange-like component that is closed at one end and has a flange at the other end.

[0030] In the diagram: 100 - forming cylinder, 101 - cylinder body, 102 - base, 200 - support slide, 300 - horizontal guide rail, 400 - first base plate, 500 - second base plate, 601 - first heater integration box, 602 - first lead screw adapter flange, 603 - first lead screw, 604 - first guide rod adapter flange, 605 - first guide rod, 606 - connecting rod, 607 - first mounting plate, 608 - first lead screw base plate, 609 - first drive gear, 610 - first servo motor, 6 11 - First driven gear, 612 - First lead screw nut, 701 - Second heater integrated box, 702 - Second lead screw adapter flange, 703 - Second lead screw, 704 - Second guide rod adapter flange, 705 - Second guide rod, 706 - Second lead screw nut, 707 - Second driven gear, 708 - Second drive gear, 709 - Second servo motor, 710 - Second lead screw base plate, 801 - Servo electric cylinder, 802 - Third guide rod, 803 - Locking flange, 900 - Elastic sealing cloth. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings.

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Example 1: like Figure 1 - Figure 11 As shown, the dual-substrate mode laser selective melting additive manufacturing apparatus of the present invention includes: a forming cylinder 100, a support slide 200, a horizontal guide rail 300, a first substrate 400, a second substrate 500, a first driving mechanism, a second driving mechanism, and a forming cylinder driving mechanism.

[0034] The forming cylinder 100 consists of a cylinder body 101 and a base 102. The cylinder body 101 is a cylindrical or square hollow structure with an opening at the top, forming a forming cavity inside for containing metal powder, substrate, etc. The base 102 matches the outer contour of the cylinder body 101 and is fixed to the base 102 by bolts, with no relative displacement between the two.

[0035] The horizontal guide rails 300 are fixed in pairs parallel to the equipment frame and are made of high-precision linear guide rails. The support slide 200 is slidably installed on the horizontal guide rails 300 via a slider, which can realize the movement and switching of the entire forming cylinder system in the printing chamber, powder cleaning chamber, and part picking chamber.

[0036] The forming cylinder drive mechanism includes a servo electric cylinder 801, a third guide rod 802, and a locking flange 803. Two servo electric cylinders 801 are fixedly installed at opposite corners of the support slide 200. Four third guide rods 802 are distributed at the four corners of the base 102, and each third guide rod 802 is fixedly connected to the base 102 via the locking flange 803. One pair (two) of the diagonally positioned third guide rods 802 are fixedly connected to the output push rod of one servo electric cylinder 801, while the other pair of third guide rods 802 provides vertical guidance to ensure the stability of the forming cylinder 100 during horizontal movement. The forming cylinder drive mechanism drives the forming cylinder 100 to move up and down along the Z-axis, making the distance between the forming cylinder 100 and components such as the laser generator and the powder spreading scraper adjustable.

[0037] The first substrate 400 and the second substrate 500 are arranged inside the cylinder 101, and can be arranged concentrically or in parallel. The horizontal gap between the two substrates is 1mm to 3mm. A high-temperature resistant elastic sealing cloth 900 (withstanding 300℃) is installed below the gap, with its upper edge adhering to the lower surface of the two substrates to catch powder leakage and prevent powder from entering the device. In addition, the horizontal gap between the outer side of each substrate and the outer perimeter of the inner wall of the cylinder 101 is 3mm to 10mm to avoid lifting and lowering jamming.

[0038] Each substrate is fitted with a sealing gasket between itself and the corresponding heater integration box to prevent powder from entering the heater integration box through the gap.

[0039] Concentric distribution: The first substrate 400 is in the center, and the second substrate 500 is on the outside; they can be concentric circles or concentric rectangles. In this case, the first lead screw 603 is solid, and the second lead screw 703 is hollow, with the first lead screw 603 coaxially nested within the second lead screw 703. The specific structure is shown below: The first drive mechanism is located below the first base plate 400 and includes a first heater integration box 601, a first lead screw adapter flange 602, a first lead screw 603, a first guide rod adapter flange 604, a first guide rod 605, a connecting rod 606, a first mounting plate 607, a first lead screw base plate 608, a first drive gear 609, a first servo motor 610, a first driven gear 611, and a first lead screw nut 612.

[0040] The first heater integrated box 601 is bolted to the bottom of the first base plate 400 and located inside the forming cylinder 100, housing a heating element and a temperature control sensor. Both ends of the first lead screw 603 and the first guide rod 605 are connected to the first heater integrated box 601 and the first lead screw base plate 608 respectively via flanges (first lead screw adapter flange 602 or first guide rod adapter flange 604). The first lead screw 603 is located at the center of the first lead screw base plate 608, and the first guide rod 605 is located at the four corners of the first lead screw base plate 608. One side of the first mounting plate 607 is fixed to the bottom of the base 102 via a connecting rod 606, and the other side is fitted with a first lead screw nut 612 and a first servo motor. 610, and the first lead screw nut 612 is fixed at the center position of the lower surface of the first mounting plate 607; the output end of the first servo motor 610 is coaxially fixed with the first driving gear 609, and both are located below the first mounting plate 607; the first driven gear 611 is fixedly connected to the lower part of the first mounting plate 607 through a bearing seat + thrust bearing (used to limit the axial displacement of the first driven gear 611), and the first driven gear 611 and the first lead screw 603 are coaxially connected through a spline, and the first driven gear 611 and the first driving gear 609 mesh with each other; the first servo motor 610 drives the first driving gear 609 to rotate, thereby driving the first driven gear 611 to drive the first lead screw 603 to rotate. Among them, the first lead screw 603 and the first lead screw nut 612 form a lead screw nut kinematic pair, which is realized by the movement mode of the nut being fixed and the lead screw rotating, so as to realize the independent lifting and lowering of the first base plate 400.

[0041] The second drive mechanism is located below the second base plate 500 and includes: a second heater integration box 701, a second lead screw adapter flange 702, a second lead screw 703, a second guide rod adapter flange 704, a second guide rod 705, a second lead screw nut 706, a second driven gear 707, a second driving gear 708, a second servo motor 709, and a second lead screw base plate 710.

[0042] The second heater integrated box 701 is sleeved on the outside of the first heater integrated box 601; the second lead screw 703 is coaxially nested on the outside of the first lead screw 603; both ends of the second lead screw 703 and the second guide rod 705 are connected to the second heater integrated box 701 and the second lead screw base plate 710 respectively through flanges (second lead screw adapter flange 702 or second guide rod adapter flange 704), and the second lead screw 703 is located at the center of the second lead screw base plate 710, and the second guide rod 705 is located at the four corners of the second lead screw base plate 710; the second lead screw nut 706 and the second servo motor 709 are both fixed on the lower surface of the base 102. The second lead screw nut 706 is located at the center of the lower surface of the base 102; the output end of the second servo motor 709 is coaxially fixed with the second drive gear 708, and both are located below the base 102; the second driven gear 707 is fixedly connected to the lower part of the base 102 through a bearing housing and a thrust bearing (used to limit the axial displacement of the second driven gear 707), and the second driven gear 707 and the second lead screw 703 are coaxially connected through a spline and mesh with the second drive gear 708; the second servo motor 709 drives the second drive gear 708 to rotate, thereby driving the second driven gear 707 to drive the second lead screw 703 to rotate. The second lead screw 703 and the second lead screw nut 706 form a lead screw-nut kinematic pair, and the movement mode of nut fixation and lead screw rotation is adopted to realize the independent lifting and lowering of the second base plate 500.

[0043] Parallel arrangement: The first substrate 400 and the second substrate 500 are arranged side by side, which can be arranged symmetrically from left to right or front to back. In this case, the first driving mechanism and the second driving mechanism are the same, and are respectively arranged side by side at the lower end of the first substrate 400 and the second substrate 500. The specific structure of the two is similar to that of the concentrically distributed second driving mechanism. However, both lead screws are solid and have the same length.

[0044] The dual-substrate mode laser selective melting additive manufacturing method of the present invention includes the following steps: S1: Import the parts to be processed, or a single part, into the SLM additive manufacturing equipment's nesting software and arrange them on the dual substrates according to the process requirements. Process requirements can be divided into printing with the same layer thickness (QX1) and printing with different layer thicknesses (QX2). For QX2, the layer thicknesses are Δ1 and Δ2, where Δ1 < Δ2. When printing QX1, all parts can be freely arranged on the dual substrates. When printing QX2, parts with a layer thickness of Δ1 must be arranged on the first substrate, and parts with a layer thickness of Δ2 must be arranged on the second substrate. Furthermore, the maximum horizontal projection cross-section of any part is not allowed to span both substrates. S2: When printing with QX1, the powder layer thickness for all parts is designed to be Δ1. The remaining SLM additive manufacturing process parameters, such as laser power, scanning speed, and infill spacing, can be matched with the structural features of the corresponding target parts. When printing with QX2, the powder layer thickness for parts arranged on the first substrate is designed to be Δ1, and the powder layer thickness for parts arranged on the second substrate is designed to be Δ2. The remaining SLM additive manufacturing process parameters, such as laser power, scanning speed, and infill spacing, can be matched with the structural features of the corresponding target parts. S3: Level the upper surfaces of the first substrate and the second substrate to keep them at the same height. S4: The powder spreading scraper first spreads a layer of powder on the double substrate. The entire powder bed surface should be flat and free of defects such as grooves, steps, and missing powder. S5: Start printing. After the first layer of laser sintering is completed, when printing QX1, both substrates descend simultaneously by Δ1. When printing QX2, the first substrate descends by Δ1 and the second substrate descends by Δ2. After both substrates descend, the powder spreading squeegee returns to below the powder feeding shaft to collect powder. After collecting the powder, the powder spreading squeegee begins to spread the second layer of powder. After the powder spreading is completed, the laser begins to sinter the second layer. S6: Repeat step S5, laser sintering layer by layer until printing is finished; when QX2 printing is performed, if the parts on the other substrate still need to be printed after the parts on the other substrate are printed, the two substrates can continue to descend according to the descent amount described in S5, or the substrate that has finished printing the parts can be stopped descending. It should also be noted that the motion constraints of the dual-base plate have the following requirements: Motion constraint symbol table For a concentric distribution, regardless of whether the first and second substrates move synchronously or asynchronously, the following condition must be met: ; ; .

[0045] In addition, such as Figure 10 , 11 As shown, for flange-type components with flanges at both ends (referred to as component one) or flange-type components with one end closed and the other end flanged (referred to as component two), component one and component two are respectively related to the width of the first base plate. and the width of the second substrate The following constraints exist. Component 1 exists in two shapes: circular and rectangular. For circular shapes: : The diameter of the maximum outer circle of the upper flange of component one.

[0046] : The diameter of the maximum outer circle of the lower flange of component one.

[0047] : The diameter of the largest outer circle of the middle frame of component one.

[0048] For rectangular shapes: : Maximum width of the upper flange of component one.

[0049] : Maximum width of the lower flange of component one.

[0050] : Maximum width of the middle frame of component one.

[0051] The dimensions of component one are related to the width of the first substrate. and the width of the second substrate The following constraints exist: or ; or ; or .

[0052] Component two also exists in both circular and rectangular shapes. For circular shapes: The maximum outer circle of the frame of component two diameter.

[0053] : The diameter of the maximum outer circle of the upper flange of component two.

[0054] For rectangular shapes: : Maximum width of the frame of component two.

[0055] : Maximum width of the upper flange of component two.

[0056] The maximum outer diameter of the upper flange of component two Or maximum width The maximum outer circle of the frame of component two Or maximum width Component 2 and the width of the first substrate and the width of the second substrate The following constraints exist: or ; or For the first prototype of small-format parts, where the parts are arranged on only one substrate (first substrate or second substrate) and the other substrate has no parts, concentric dual-substrate SLM additive manufacturing or parallel dual-substrate SLM additive manufacturing (left-right or front-back distribution) can be selected. The lifting amount of the other substrate can be adjusted to save powder filling in that area. Combined with the existing dynamic powder spreading technology of the same layer, the efficiency of SLM additive manufacturing can be effectively improved and the cost of first-piece development can be saved.

[0057] Example 2: This embodiment takes a flange-type component with one end closed and the other end with a flange as an example to illustrate the progress of this device in reducing support structure and saving materials.

[0058] The component has an ellipsoidal base, and the outermost diameter of the upper flange of the ellipsoidal base is [not specified]. The flange is 450mm thick, 10mm thick, and has a lower surface height of 400mm. The maximum outer diameter of the ellipsoidal base frame is... The frame structure is 380mm long, with a wall thickness of 2mm, and the material is 17-4PH stainless steel; the first substrate is in the positive direction and its side length is... The second substrate is 800mm in diameter and is also square with a side length of [missing information]. It is 300mm.

[0059] The dual-substrate mode laser selective melting additive manufacturing apparatus for manufacturing this component preferably employs a concentric distribution, and its manufacturing method specifically includes the following steps: S1: The printing direction of the ellipsoidal base is with the opening facing upwards, i.e., the flange feature is at the top, to facilitate powder cleaning after printing; the flange width exceeds the width of the first substrate by 50mm, and there is still a 20mm width of the flange to be printed on the first substrate. Considering that the frame structure of the ellipsoidal base has a wall thickness of only 2mm and a height of 380mm, a solid support structure is designed for the lower surface edge of the 20mm width of the flange, and a block-shaped virtual support structure is designed for the filling area. An umbrella-shaped array is used to break the solid support structure, and the block-shaped virtual support structure is tilted on the solid support structure to reduce the cross-sectional area of ​​each layer and improve the forming efficiency; an enveloping mesh rib structure is designed on the inner and outer surfaces of the ellipsoidal base frame structure to reduce buckling instability during the large-area printing process. The mesh rib unit is 50mm×50mm, the mesh rib width is 1mm, and the height is 0.2mm; the 50mm wide flange feature is laid out on the second substrate, and the remaining features are laid out on the first substrate, with the center of the first substrate coaxial with the center of the ellipsoidal base, and Δ1 and Δ2 are set to 0.04mm; S2: Based on the powder layer thickness Δ1 on the first substrate being 0.04mm and the powder layer thickness Δ2 on the second substrate being 0.04mm, the appropriate laser power, scanning speed, and filling spacing are matched as follows: filling laser power is 240W, scanning speed is 950mm / s, and filling spacing is 0.1mm; contour laser power is 150W, and scanning speed is 500mm / s. S3: Level the upper surfaces of the first substrate and the second substrate to keep them at the same height. S4: The powder spreading scraper first spreads a layer of 17-4PH stainless steel powder on the double substrate. The entire powder bed surface should be flat and free of defects such as grooves, steps, and missing powder. S5: The forming cylinder is filled with high-purity argon gas in the forming chamber, ensuring that the oxygen content in the forming cylinder is below 300ppm; the heating temperature of the first substrate and the second substrate is 100℃; when the oxygen content and heating temperature reach the design values, printing begins; after the first layer of laser sintering is completed, the first substrate descends by 0.04mm, while the second substrate remains stationary; the powder spreading squeegee returns to below the powder lowering shaft to collect powder, and after collecting the powder, the powder spreading squeegee begins to spread the second layer of powder; after the powder spreading is completed, the laser begins to sinter the second layer; S6: Repeat step S5, laser sintering layer by layer; when printing to layer 9500, the first layer appears on the lower surface of the flange feature. The 50mm wide flange feature is directly laser sintered onto the second substrate to form a metallurgical bond, while the remaining features are laser sintered onto the first substrate; after this layer is printed, the first and second substrates descend simultaneously by 0.04mm; after the two substrates descend, the powder-spreading squeegee returns to below the powder shaft to collect powder. After collecting the powder, the powder-spreading squeegee begins to spread powder for layer 9501; after the powder spreading is completed, the laser begins to sinter layer 9501; subsequently, after each layer is printed, the two substrates descend simultaneously by 0.04mm until printing is finished; In this embodiment, the SLM additive manufacturing method for the ellipsoidal base component directly reduces the solid support structure of the 50mm wide flange feature by nearly 380mm in height, effectively improving forming efficiency. Furthermore, the nearly 380mm high area of ​​the second substrate does not require powder filling; based on a second substrate width of 300mm, this saves nearly 160kg of powder.

[0060] Example 3: This embodiment demonstrates multi-layer, high-efficiency SLM additive manufacturing of different parts within the same compartment.

[0061] This embodiment preferably adopts a dual-substrate mode with left and right distributed substrates.

[0062] Its manufacturing method specifically includes the following steps: S1: Import the designed parts into the SLM additive manufacturing equipment layout software and arrange them on the double substrate according to the process requirements. Since the imported parts have different structural features, in this embodiment, Δ1=0.04mm and Δ2=0.08mm. The parts with a layer thickness of Δ1=0.04mm are arranged on the first substrate, and the parts with a layer thickness of Δ2=0.08mm are arranged on the second substrate. The maximum horizontal projection cross section of any part is not allowed to span the double substrate. S2: Based on the powder layer thickness Δ1=0.04mm for the parts arranged on the first substrate and the powder layer thickness Δ2=0.08mm for the parts arranged on the second substrate, the SLM additive manufacturing process parameters such as laser power, scanning speed, and fill spacing are matched with the corresponding target part structural features. S3: Level the upper surfaces of the first substrate and the second substrate to keep them at the same height. S4: The powder spreading scraper first spreads a layer of powder on the double substrate. The entire powder bed surface should be flat and free of defects such as grooves, steps, and missing powder. S5: Start printing. After the first layer of laser sintering is completed, the first substrate descends by 0.04mm and the second substrate descends by 0.08mm. After both substrates descend, the powder spreading squeegee returns to below the powder feeding shaft to collect powder. After the powder collection is completed, the powder spreading squeegee begins to spread the second layer of powder. After the powder spreading is completed, the laser begins to sinter the second layer. S6: Repeat step S5, laser sintering layer by layer until printing is finished; when the parts on one substrate are printed, if the parts on another substrate still need to be printed, the two substrates can continue to descend according to the descent amount described in S5, or the substrate that has finished printing the parts can stop descending. This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A dual-substrate mode laser selective melting additive manufacturing apparatus, characterized in that: It includes a forming cylinder, a first substrate, a second substrate, a first substrate driving mechanism, and a second substrate driving mechanism; Both the first substrate and the second substrate are placed inside the forming cylinder. The first substrate and the second substrate form a dual substrate mode. The two substrates are arranged in a concentric or parallel manner, and the horizontal gap between the two substrates is designed to be 1mm to 3mm. The lower surface of the horizontal gap is designed with an elastic and high-temperature resistant elastic sealing cloth, which is used to receive the powder between the two substrates. The first substrate and the second substrate are respectively connected to the first substrate driving mechanism and the second substrate driving mechanism. The first substrate driving mechanism and the second substrate driving mechanism are respectively used to drive the corresponding substrates to rise and fall independently along the Z direction, so that the two substrates can move synchronously or asynchronously in the forming cylinder, and the amount of descent of the first substrate and the second substrate after single-layer sintering can be set respectively.

2. The dual-substrate mode laser selective melting additive manufacturing apparatus according to claim 1, characterized in that: Both the first substrate driving mechanism and the second substrate driving mechanism include a servo motor, a gear pair, and a lead screw and nut pair that are connected in sequence. When the first substrate and the second substrate are concentrically distributed, the lead screw of the first substrate driving mechanism is a solid lead screw, and the lead screw of the second substrate driving mechanism is a hollow lead screw. The two types of lead screws are coaxially nested. When the first substrate and the second substrate are arranged side by side, the lead screws of both the first substrate driving mechanism and the second substrate driving mechanism are solid lead screws. They are arranged parallel to each other and have the same length.

3. The dual-substrate mode laser selective melting additive manufacturing apparatus according to claim 2, characterized in that: The first substrate and the second substrate are respectively fixedly connected to the lead screw adapter flange of the corresponding drive mechanism through independent heater integration boxes; sealing gaskets are provided between the two types of substrates and the corresponding heater integration boxes; the outer peripheral horizontal gap between the outer side of the substrate and the inner wall of the forming cylinder is 3mm to 10mm.

4. The dual-substrate mode laser selective melting additive manufacturing apparatus according to claim 1, characterized in that: The first substrate driving mechanism and the second substrate driving mechanism also include several sets of guide rod assemblies for guiding and supporting the Z-axis movement of each substrate.

5. The dual-substrate mode laser selective melting additive manufacturing apparatus according to claim 1, characterized in that: The forming cylinder includes a cylinder body and a base that are fixedly connected; a support slide is provided at the lower end of the base, and a forming cylinder drive mechanism is installed between the support slide and the base. The forming cylinder drive mechanism includes a servo electric cylinder, a guide rod, and a locking flange to realize the Z-axis movement of the forming cylinder; a horizontal guide rail is provided at the lower end of the support slide, and the support slide can slide along the horizontal guide rail to realize the movement and switching of the entire device in the printing chamber, the powder cleaning chamber, the part picking chamber, and other workstations.

6. A dual-substrate mode laser selective melting additive manufacturing method, characterized in that: The dual-substrate mode laser selective melting additive manufacturing apparatus according to any one of claims 1-5 includes the following steps: S1: According to the process layout requirements of the parts to be manufactured, arrange the parts to be manufactured on the first substrate and / or the second substrate, and determine the powder layer thickness Δ1 of the first substrate and the powder layer thickness Δ2 of the second substrate, and Δ1≤Δ2. S2: Set the SLM additive manufacturing process parameters according to the powder layer thickness of the corresponding parts on each substrate; S3: Level the first substrate and the second substrate so that their upper surfaces are on the same horizontal plane, and then apply powder. S4: Perform laser sintering according to the slicing scanning path of the corresponding area of ​​the first substrate and / or the corresponding area of ​​the second substrate; S5: After the single-layer sintering is completed, the first substrate is lowered by Δ1 and / or the second substrate is lowered by Δ2; S6: Repeat the powder spreading, laser sintering, and substrate lowering steps until the part to be manufactured is printed.

7. The dual-substrate mode laser selective melting additive manufacturing method according to claim 6, characterized in that: The process layout requirements include, but are not limited to, one or more of the following conditions; Whether the optional powder layer thickness of the components to be manufactured is different, whether the components to be manufactured need to be provided with a support structure, and whether the maximum horizontal projection cross section of any part spans the two substrates.

8. The dual-substrate mode laser selective melting additive manufacturing method according to claim 7, characterized in that: When the optional powder layer thickness of the components to be manufactured is different and the maximum horizontal projected cross section of any part does not span the two substrates: In step S1, the thin-layer component is arranged on the first substrate, and the thick-layer component is arranged on the second substrate. In step S4, laser sintering is performed according to the slicing scanning path of the corresponding area of ​​the first substrate and the corresponding area of ​​the second substrate; In step S5, the first substrate descends by Δ1, and the second substrate descends by Δ2; In step S6, when the printing of a part on one substrate is completed and the printing of a part on another substrate still needs to continue, the substrate that has completed printing can choose to stop descending or continue descending according to the set descent amount.

9. The dual-substrate mode laser selective melting additive manufacturing method according to claim 7, characterized in that: For components requiring support structures, such as those with flanges at both ends or those closed at one end and with a flange at the other, a concentrically distributed dual-substrate SLM additive manufacturing mode is adopted: In step S1, the component frame structure is arranged on the first substrate, and the overhanging structure that needs to be supported and extends beyond the first substrate is arranged on the second substrate. In steps S4 to S6, before the first layer appears on the lower surface of the suspended structure, the second substrate remains in its initial flush position, and the first substrate descends layer by layer according to the set layer thickness and laser-sintersects the structural frame structure; when the first layer appears on the lower surface of the suspended structure, the powder is laser-sintered and the suspended structure forms a metallurgical bond with the upper surface of the second substrate; then the first substrate and the second substrate descend synchronously with the same layer thickness until the printing is completed.

10. The dual-substrate mode laser selective melting additive manufacturing method according to claim 7, characterized in that: When the maximum width of the horizontal projection of the component to be manufactured is less than the width of either the first substrate or the second substrate: In step S1, the target component is arranged on only one of the first substrate or the second substrate, and the other substrate is an empty substrate. In step S4, laser sintering is performed only on the slice scanning path of the substrate containing the parts; In step S5, the substrate containing only the component is lowered by the corresponding layer thickness, while the other substrate remains stationary.

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