A high stress material printing composite substrate and forming method

Abstract

The present invention relates to the field of metal additive manufacturing technology. In order to solve the technical problem that the substrate of a large-size product formed by laser selective melting is difficult to match, resulting in deformation, tearing of the substrate and stress cracking of the product, the present invention provides a high-stress material printing composite substrate and forming method, including a stage, a main bearing plate is arranged on the stage, and the main bearing plate is provided with staggered wedge grooves, and wedge blocks for supporting parts are installed in the wedge grooves, and active gaps for dispersing stress are reserved between the wedge blocks. If the part shrinks along the short side direction of the main bearing plate, the wedge block slides along the direction of the wedge groove due to the gap between the wedge block and the wedge groove of the main bearing plate; if the part shrinks a lot, the wedge blocks will approach each other, and the gap between them can effectively resist the shrinkage deformation of the part. The huge internal energy generated by the forming stress of the part is effectively absorbed by the effective movement of the wedge block, reducing the risk of deformation and cracking of the part.

Description

Technical Field

[0001] The present invention relates to the technical field of metal additive manufacturing, and in particular to a high-stress material printing composite substrate and a forming method. Background Art

[0002] Laser selective melting forming technology has the characteristics of rapid melting and solidification, but stress and shrinkage deformation often occur when forming large-sized parts. Especially for modern large-sized laser selective melting forming equipment, as the size of the formed parts increases, higher requirements are put forward for controlling deformation and cracking.

[0003] When the thickness of the substrate is thin, the deformation resistance of the substrate itself may not be sufficient to resist the shrinkage deformation of the parts. Especially when the mechanical properties of the substrate material are not as good as those of the formed product material, the substrate is prone to bending, tearing and other problems, and it also makes it difficult to unload the parts from the stage. In severe cases, the parts may be detached from the substrate and cannot be formed, resulting in product scrapping. On the other hand, if the substrate is too thick, when the size of a single part is close to two-thirds or more of the maximum forming size of the equipment, especially when printing at full load, a substrate thickness of more than 100mm is required. However, under the existing domestic substrate processing conditions, the substrate with a size of 800mm*800mm*100mm or more, which is the same material as the product or has similar thermophysical properties, is prepared. The substrate strength obtained by the conventional hot rolling process is low and cannot meet the requirements of product forming and shape control. Moreover, the thickness of the substrate cannot be increased indefinitely, because the subsequent processing volume will increase and the efficiency will also decrease. In addition, as the size increases, the control of internal defects becomes more difficult, which is not conducive to product forming.

[0004] At the same time, the stress of the part itself is also large. If the substrate strength is too high, the substrate may not deform but the part may tear, resulting in product scrapping.

[0005] The above problems have seriously restricted the development of laser selective melting forming technology, especially the forming of large-size products. Summary of the invention

[0006] In order to solve the technical problem that large-size product substrates formed by laser selective melting are difficult to match, resulting in substrate deformation, tearing and product stress cracking, the present invention provides a high-stress material printing composite substrate and a forming method.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] As one aspect of the present invention, there is provided a composite substrate for printing high-stress materials, comprising a stage, a main load-bearing plate is arranged on the stage, the main load-bearing plate is provided with staggered wedge grooves, wedge blocks for supporting parts are installed in the wedge grooves, and active gaps are reserved between the wedge blocks to disperse stress by coordinating movement and deformation of the wedge blocks.

[0009] If the part shrinks along the short side of the main bearing plate, because the part is not in contact with the main bearing plate but directly in contact with the wedge block, there is a gap between the wedge block and the wedge groove of the main bearing plate, and there is also a gap between each other. The wedge block slides along the wedge groove and deforms slightly along the normal vector direction of the main bearing plate. If the part shrinks a lot, the wedge blocks will move closer to each other, and the gap between them can effectively resist the shrinkage and deformation of the part. In this way, the huge internal energy generated by the forming stress of the part is effectively absorbed through the effective movement of the wedge block, reducing the risk of deformation and cracking of the part.

[0010] By reserving active gaps between the wedge blocks, when the parts shrink, the gaps between the wedge blocks can disperse the stress and alleviate the problem of stress concentration, which helps to avoid deformation or cracking caused by excessive local stress in the parts.

[0011] When the parts shrink, the movement between the wedge blocks can effectively absorb the huge internal energy generated by the forming stress of the parts. The energy is dispersed and absorbed, which reduces the stress concentration of the parts and reduces the risk of deformation and cracking of the parts.

[0012] When the part shrinks a lot, the gap between the wedge blocks will automatically decrease, so that the wedge blocks are closer to each other to adapt to the deformation of the part. This adaptive adjustment capability helps to maintain the stability and structural integrity of the part.

[0013] Furthermore, the wedge blocks include four-corner wedge blocks arranged at the four corners of the main bearing plate and four-side wedge blocks arranged at the four sides of the main bearing plate.

[0014] Furthermore, large-sized first bosses are arranged at intervals on the short sides of the main load-bearing plate, and small-sized second bosses are arranged at intervals on the long sides of the main load-bearing plate. First wedge-shaped grooves are formed between the first bosses, and second wedge-shaped grooves are formed between the second bosses. The number of first wedge-shaped grooves is less than the number of second wedge-shaped grooves.

[0015] Furthermore, the wedge block also includes a patch wedge block arranged in the middle of the main bearing plate.

[0016] The patch wedge is located in the middle of the main bearing plate to provide additional support. It can fill the gap between the corner wedge and the side wedge, enhancing the stability and uniformity of the entire support structure. The presence of the patch wedge can help disperse the stress caused by part shrinkage and reduce the risk of stress concentration.

[0017] The patch wedge is positioned so that it can apply support force to the middle area of ​​the part. When the part shrinks, the patch wedge can balance the stress distribution and prevent uneven deformation or cracking of the part. It helps maintain the overall stability of the part and improves the forming accuracy during the printing process.

[0018] The patch wedge block acts as a supplementary support element to enhance the strength of the entire structure. It can help resist external stress and loads and reduce the risk of deformation and damage of parts during use. The presence of the patch wedge block can improve the structural stability and reliability of the composite substrate.

[0019] By introducing patch wedges, additional support and stability can be provided in the middle area of ​​the main bearing plate, balancing the stress distribution and enhancing the strength of the entire structure. This helps reduce the risk of part deformation, cracking and failure, and improves the quality and reliability of the composite base plate.

[0020] Furthermore, a heating groove is provided on the top of the loading platform, a heating wire is embedded in the heating groove, and the main bearing plate and the loading platform are respectively provided with a first screw hole and a second screw hole for fastening the connection with fixing screws.

[0021] By setting a heating groove on the top of the stage and embedding a heating wire, a heating function can be provided. This is very important for certain materials or processes, such as high-stress materials that require controlled printing temperature. The heating wire in the heating groove can provide a heat source to keep the stage, main bearing plate, and wedge block at a suitable temperature, reduce the temperature gradient during the part forming process, and avoid uneven stress due to different shrinkage deformations in different parts of the part, thereby controlling the stress.

[0022] The main load-bearing plate and the loading platform are respectively provided with screw holes, and high-strength screws can be used for fastening connection. This fixed connection method can ensure a stable connection between the main load-bearing plate and the loading platform, and ensure the structural integrity and stability of the device.

[0023] Furthermore, the main bearing plate is also provided with a pin hole, in which a positioning pin is provided for limiting the free sliding of the wedge block.

[0024] By setting a positioning pin in the pin hole, the free sliding of the wedge block can be limited. The presence of the positioning pin fixes the position of the wedge block in the wedge groove and prevents it from moving unnecessarily. This ensures that the wedge block is always in the proper position when subjected to stress and pressure, providing reliable support and limiting deformation of the parts.

[0025] The locating pins help to enhance the stability of the entire structure. By fixing the position of the wedge block, the locating pins can prevent the wedge block from loosening or misaligning due to force. This helps maintain the structural integrity of the printing unit and provides a more stable support platform, thereby improving the reliability and consistency of the printing process.

[0026] The presence of the locating pins can help ensure that the wedge blocks stay in a specific position, thereby precisely controlling the stress distribution of the part. By limiting the movement of the wedge blocks, the path and distribution of stress transfer can be adjusted to achieve more precise control and predictability of the deformation behavior of the part.

[0027] By setting pin holes and using positioning pins, the free sliding of the wedge block can be limited, the structural stability can be enhanced, and the stress distribution can be precisely controlled, which helps to improve the stability and consistency of the printing device and provide better control for the printing process.

[0028] Furthermore, the bottom of the wedge block is a dovetail protrusion, the upper part is a cube, the top is a rough plane, the wedge groove is a dovetail groove, the main load-bearing plate and the stage are made of the same material, and the wedge block and the part are made of the same material.

[0029] Since the bottom of the wedge block is a dovetail protrusion, it can fit tightly with the dovetail groove. The upper part of the wedge block is a cube, which can provide a wider support area, help disperse stress and alleviate stress concentration problems. This design can reduce the stress of the part or wedge block, reduce the risk of deformation and cracking, and improve the quality of the printing process.

[0030] When printing starts, the scraper spreads the powder through reciprocating motion. The rough surface on the top of the wedge block can increase the bonding force between the powder and it, preventing the powder from agglomerating and being scraped away. At the same time, it increases the friction with the part, providing better damping and stability. This helps prevent the part from sliding or misaligning during printing, and provides more reliable support and limits deformation of the part.

[0031] Material consistency ensures that they work under the same thermal expansion coefficient and mechanical properties. This can reduce stress and deformation problems caused by mismatched thermal expansion between different materials, and improve overall stability and print quality.

[0032] In short, the wedge block is made of the same material as the part, and has basically the same mechanical properties. It is also smaller than the structural strength and material strength of the main load-bearing plate. It itself has certain elastic deformation and plastic deformation. The deformation of the part can be effectively released through the direction of the wedge block. This completely avoids the huge obstacle of the main load-bearing plate not matching the material of the part and being unable to form directly on its surface.

[0033] As another aspect of the present invention, a method for printing and forming a high stress material is provided, and a composite substrate is printed based on the above-mentioned high stress material, including the following method:

[0034] Use additive manufacturing software to simulate part deformation and stress, and calculate maximum deformation, maximum stress, stress distribution, and deformation distribution;

[0035] Add design allowance to the bottom of the part;

[0036] A wedge-shaped groove is provided at the margin portion;

[0037] Make the margin part correspond to the wedge block, and the groove width of the wedge groove is larger than the active gap;

[0038] If the wedge block does not fully cover the main bearing plate, set positioning pins on both sides of the wedge block to limit the position;

[0039] Fix the main bearing plate to the stage with fixing screws;

[0040] Turn on the heating wire in the stage to heat the main bearing plate to a temperature of 200-500°C. Tighten the fixing screws at the four corners to fix the main bearing plate.

[0041] Close the door of the 3D printer and use the scraper to spread the powder until the powder completely buries the wedge-shaped block and forms a powder with a thickness of 0 to 0.06 mm on its upper surface;

[0042] The designed parts are sliced ​​through the laser selective melting forming professional software, and the sintering parameters are given to generate the printing program;

[0043] The printing program is transferred into the printing device, and the air is inflated until the oxygen content is less than 0.1%, and then the printing program is run, and the laser emits light for printing;

[0044] After each layer is printed, the main load-bearing platform drops one layer thickness, the scraper spreads the powder, and the laser emits light for sintering, and this cycle repeats until the cross part is formed;

[0045] After the part is formed, the heating wire stops heating and waits for the temperature to drop to the preset temperature;

[0046] Open the hatch, remove the fixing screws, and remove the parts together with the main bearing plate and wedge block;

[0047] The parts are cut from the wedge blocks by wire cutting, and then the wedge blocks are removed from the main bearing plate.

[0048] By using additive manufacturing software to simulate and analyze parts, parameters such as maximum deformation, maximum stress, stress distribution, and deformation distribution can be measured, which helps to predict problems that may occur in the printing process of parts and optimize design and process parameters to reduce deformation and stress concentration and improve printing quality.

[0049] Adding a design allowance at the bottom of the part and opening a wedge-shaped groove at the allowance position can provide a certain deformation compensation space for the part and form an active gap between the wedge block and the wedge-shaped groove to disperse stress and absorb energy, reducing the risk of deformation and cracking.

[0050] By setting positioning pins on both sides of the wedge block, the position of the wedge block can be fixed to prevent it from moving or misaligning, which helps to maintain the stability of the entire structure and reduce the risk of deformation of parts.

[0051] After the part is formed, the part is separated from the main bearing plate and wedge block by removing the fixing screws. This facilitates subsequent post-processing steps, such as wire cutting to cut the part from the wedge block and further complete the preparation of the part.

[0052] Through the above-mentioned high-stress material printing and forming method, simulation analysis optimization, deformation compensation, active gap, heating control, powder laying, cyclic printing, convenient disassembly, etc. can be provided, which helps to improve the quality of printed parts, reduce the risk of deformation and cracking, and promote the effective printing and forming of high-stress materials.

[0053] Furthermore, the part is cross-shaped, which can reduce support.

[0054] Furthermore, the main bearing plate is inspected for flatness. If the flatness is greater than 0.06 mm, grinding is performed. The smoothness of the fit between the wedge block and the dovetail groove of the main bearing plate is checked. If jamming occurs, the wedge groove and wedge block of the main bearing plate are reprocessed.

[0055] By inspecting and grinding the flatness of the main bearing plate, we can ensure that the flatness of the main bearing plate meets the requirements. This is very important for the printing accuracy and quality of the parts, because a flat bearing plate can provide a more stable support platform to ensure that the parts maintain accurate positioning and shape during the printing process.

[0056] Check the smoothness of the wedge block and the dovetail groove of the main bearing plate. If there is a jam or a problem with the dovetail groove of the main bearing plate, reprocessing the wedge groove and wedge block of the main bearing plate can solve this problem. A good wedge block fit can ensure the free sliding of the wedge block in the wedge groove, achieve effective stress dispersion and absorption, and reduce the risk of part deformation and cracking.

[0057] The stability and consistency of the main bearing plate can be ensured by flatness inspection and optimization of wedge block matching. This is very important for the positioning accuracy of parts during printing, the uniformity of stress distribution, and the stability of the overall structure. A stable main bearing plate and a good wedge block match can ensure the reliability and consistency of the part printing process.

[0058] Through the above inspection and processing steps, the flatness of the main bearing plate and the wedge block fit can be optimized to improve the accuracy, stability and consistency of the printing device. This helps reduce the risk of part deformation, cracking and failure, and improves printing quality and reliability.

[0059] The beneficial effects brought by implementing the present invention are:

[0060] If the part shrinks along the short side of the main bearing plate, because the part is not in contact with the main bearing plate but directly in contact with the wedge block, there is a gap between the wedge block and the wedge groove of the main bearing plate, and there is also a gap between each other. The wedge block slides along the wedge groove and deforms slightly along the normal vector direction of the main bearing plate. If the part shrinks a lot, the wedge blocks will move closer to each other, and the gap between them can effectively resist the shrinkage and deformation of the part. In this way, the huge internal energy generated by the forming stress of the part is effectively absorbed through the effective movement of the wedge block, reducing the risk of part deformation and cracking, and solving the technical problem of difficult matching of substrates for large-size products formed by laser selective melting, resulting in substrate deformation, tearing and product stress cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 A three-dimensional diagram of a composite substrate printed with a high-stress material provided in an embodiment of the present invention;

[0062] Figure 2 A structural diagram of a four-corner wedge block provided by an embodiment of the present invention;

[0063] Figure 3 A three-dimensional structural diagram of the main bearing plate provided in an embodiment of the present invention;

[0064] Figure 4 A top view of the main bearing plate provided in an embodiment of the present invention;

[0065] Figure 5 A three-dimensional diagram of a four-sided wedge block provided by an embodiment of the present invention;

[0066] Figure 6 A front view of a four-sided wedge block provided in an embodiment of the present invention;

[0067] Figure 7 A structural diagram of a patch wedge block provided by an embodiment of the present invention;

[0068] Figure 8 A structural diagram of a stage provided in an embodiment of the present invention;

[0069] Fig. 9 A diagram of the heating wire structure provided by an embodiment of the present invention;

[0070] Fig.10 A structural diagram of a fixing screw provided in an embodiment of the present invention;

[0071] Fig.11 Part structure provided by the embodiment of the present invention Figure 1 ;

[0072] Fig.12 Part structure provided by the embodiment of the present invention Figure 2 ;

[0073] Fig.13 Part structure provided by the embodiment of the present invention Figure 3 ;

[0074] Fig.14 A three-dimensional diagram of a composite substrate support part provided by an embodiment of the present invention;

[0075] Fig.15 A top view of a composite substrate supporting component provided in an embodiment of the present invention.

[0076] In the figure: 1. stage; 2. main bearing plate; 3. four-corner wedge blocks; 4. four-side wedge blocks; 5. patch wedge blocks; 6. heating wire; 7. parts; 8. fixing screws; 9. positioning pins; 11. heating groove; 12. second screw hole; 21. first screw hole; 22. pin hole; 31. first dovetail groove; 32. second dovetail groove; 33. first boss; 34. second boss; 35. supplementary boss; 71. wedge groove. DETAILED DESCRIPTION

[0077] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0078] See also Figures 1 to 15 A high stress material printing composite substrate and forming method, the present invention takes the forming chamber as a rectangle as an example for explanation, the composite substrate is also a rectangle, and a reinforced composite substrate is designed for this purpose, such as Figure 1 shown.

[0079] See also Figure 2 The composite substrate includes four-corner wedge blocks 3, a main bearing plate 2, a stage 1, a heating wire 6, fixing screws 8 and four-side wedge blocks 4.

[0080] Specific position relationship and features: It includes a loading platform 1 provided at the bottom for support, and a heating groove 11 (such as Figure 8 As shown), a heating wire 6 is installed in the heating groove 11, a main bearing plate 2 is arranged above the stage 1, and a four-corner wedge block 3 and a patch wedge block 5 are arranged above the main bearing plate 2.

[0081] See also Figure 2 The bottom of the four-corner wedge block 3 is a dovetail-shaped protrusion, the upper part is a square, and the top is flat. Its material is consistent with the forming material of the part 7. This embodiment is explained by taking the forming of a high-stress material TC4 titanium alloy part as an example. The four-corner wedge block is also prepared by mechanical processing using free forging billets or cold-rolled TC4 plates as raw materials. The tensile strength of the four-corner wedge block 3 is ≥930mpa, the yield strength is ≥825Mpa, and the elongation is ≥8%. The upper surface is sandblasted after machining, and the surface roughness Ra after treatment is 3.2~6.3.

[0082] See also Figure 3 and Figure 4 , the main bearing plate 2 contains crisscross dovetail grooves. In order to reduce the strength loss of the main bearing plate 2, 3 to 7 first dovetail grooves 31 are set along the width direction (short side) of the main bearing plate 2. The width w2 of the first dovetail groove 31 is 20 to 50 mm. The interval range w1 of the first dovetail groove 31 is 50 to 100 mm. The first dovetail groove 31 has a large spacing, and is separated by a large-sized square first boss 33 in the middle. 5 to 30 second dovetail grooves 32 are set along the length direction (long side) of the main bearing plate 2. The width h2 of the second dovetail groove 32 is 15 to 40 mm. The interval range h1 is 30 to 80 mm. The second dovetail groove 32 has a small spacing, and is separated by a small-sized square second boss 34 in the middle. The number of the first dovetail grooves 21 is less than the number of the second dovetail grooves 32. In addition, a supplementary boss 35 is designed at the edge of the main bearing plate 2.

[0083] See also Figure 4 In order to facilitate the close connection between the main bearing plate 2 and the transmission mechanism, screw holes 21 are opened at the four corners. In order to facilitate the fixation with the wedge block, a plurality of pin holes 22 are opened in the second dovetail groove 32 in the main bearing plate 2. The pin holes 22 can be determined according to the actual position of the wedge block.

[0084] The material of the main bearing plate 2 is high-strength steel, with a tensile strength ≥1800Mpa, a yield strength ≥1200Mpa, and an elongation ≥10%. Its yield strength is greater than the tensile strength of the TC4 part after laser selective melting. The elongation is also higher than that of the TC4 material, and it has good toughness. It bears most of the stress during the printing process of the TC4 part, because its strength is much greater than the deformation stress of the part, and it can effectively resist the deformation of the part. The thickness H of the main bearing plate 2 is 30-60mm;

[0085] See also Figure 1 , the four-corner wedge blocks 3 are located in the dovetail grooves at the four corners of the main bearing plate 2, and are fixed by the gap between the dovetail and the groove. The gap between the two is t, which is 0.2~1mm, and its value can be freely selected and combined according to the size of the formed part 7 and the stress level. That is, the main bearing plate 2 can be fixed, while the dovetail boss size of the four-corner wedge blocks 3 is uncertain, and multiple wedge blocks 3 with different sizes and specifications are pre-processed. When the product needs to be printed, according to the simulated shrinkage amount of part 7 and the set t value, the four-corner wedge blocks 3 with appropriate size specifications are selected and assembled with the groove of the main bearing plate 2. It not only avoids the wedge block 3 from being too loose due to the gap being too large, but also absorbs energy through the four-corner wedge blocks 3 sliding along the dovetail groove according to the deformation of the formed part, reduces the risk of part cracking by coordinating the deformation, and offsets its deformation.

[0086] See also Figure 5 and Figure 6 , the bottom of the four-sided wedge block 4 is a dovetail-shaped protrusion, and the upper part is a cube. The top is flat. Its material is consistent with the forming material of part 7. This embodiment takes the forming of high-stress material TC4 titanium alloy parts as an example for explanation. The four-sided wedge block 4 should also be made of TC4 material, which is prepared by mechanical processing using free forging billet or cold-rolled TC4 plate as raw material. The tensile strength of the four-sided wedge block 4 is ≥930mpa, the yield strength is ≥825Mpa, and the elongation is ≥8%. The upper surface is sandblasted after machining, and the surface roughness Ra after treatment is 3.2~6.3. Its length L is 30~80mm; the width H1 is 30~80mm; the height M is consistent with the height P of the four-corner wedge block. That is, M=P, which is 20~40mm. The angle a between the boss and the horizontal plane is 45~75°, and its size is consistent with the dovetail groove angle of the main bearing plate and the angle of the four-corner wedge block 3 to meet the matching relationship.

[0087] The boss height N is 10-20mm. Its size is smaller than the dovetail groove depth of the main bearing plate, and the clearance is matched. The clearance size is as follows Figure 1 As shown in t.

[0088] The four-sided wedge blocks 4 are embedded in the transverse dovetail grooves of the long sides of the main bearing plate 2. The four-sided wedge blocks 4 are not in direct contact with each other. Figure 1 There is a longitudinal gap L1 between the four-sided wedge blocks 4, and the range of L1 is 0.1~1mm; the range of the transverse gap w4 is 0.1~1mm.

[0089] The main mechanism of action of the four-sided wedge block 4: If part 7 shrinks along the short side of the main bearing plate 2. Because part 7 is not in contact with the main bearing plate 2 but directly in contact with the wedge block, there is a gap between the wedge blocks and the dovetail groove of the main bearing plate 2, and there is also a gap between each other. The wedge block slides along the dovetail groove and deforms slightly along the normal vector direction of the main bearing plate. If part 7 shrinks a lot, the wedge blocks will move closer to each other, and the gap between them can effectively resist the shrinkage and deformation of the part. In this way, the huge internal energy generated by the forming stress of the part is effectively absorbed through the effective movement of the wedge block, reducing the risk of deformation and cracking of part 7.

[0090] At the same time, the wedge block is made of the same material as the part 7, and its mechanical properties are basically the same, and are smaller than the structural strength and material strength of the main bearing plate 2. It has certain elastic deformation and plastic deformation, so the deformation of the part is effectively released through the direction of the wedge block. In this way, the material mismatch between the main bearing plate 2 and the part 7 is completely avoided. During the printing process, the powder of the part material melts because its wettability is different from that of the main bearing material, and it cannot be effectively spread and wetted, and cannot be directly formed on its surface.

[0091] See also Figure 7 , a patch wedge block 5 is arranged in the middle, the bottom of the patch wedge block 5 is a dovetail-shaped protrusion, and the upper part is a rectangular parallelepiped. The top is flat. Its material is consistent with the forming material of part 7. This embodiment takes the forming of high-stress material TC4 titanium alloy parts as an example for explanation. The patch wedge block 5 should also be TC4 material, which is prepared by mechanical processing with free forging billet or cold-rolled TC4 plate as raw material. The patch wedge block 5 has a tensile strength of ≥930Mpa, a yield strength of ≥825Mpa, and an elongation of ≥8%. The upper surface is sandblasted after machining, and the surface roughness Ra after treatment is 3.2~6.3.

[0092] Its mechanism of action is completely consistent with that of the four-corner wedge block 3 and the four-side wedge block 4, so it is not necessary to elaborate on it in this paragraph.

[0093] The patch wedge block 5 has a different shape because it needs to cooperate with the wedge block in the dovetail groove distributed along the long side in the middle of the main bearing plate 2.

[0094] It should be pointed out that although the dovetail bosses and other parts of the four-sided wedge block 3, the four-corner wedge block 4, and the patch wedge block 5 have different sizes, their tops are completely flush with the main bearing plate 2 during free cooperation and maintain the same horizontal plane, otherwise the scraper cannot spread powder during printing.

[0095] See also Figure 8The stage 1 is composed of a second screw hole 12 and a heating groove 11. Its main function is to support the main bearing plate 2 to install the heating wire 6. The heating wire 6 is embedded in the heating groove 11 of the stage, and the main bearing plate 2 is connected to the motion mechanism through the fixing screw passing through the second screw hole 12 of the stage, thereby maintaining the upward and downward joint movement.

[0096] The stage 1 can be made of aluminum alloy, stainless steel or other materials, but based on the deformation characteristics of large-sized parts, it is preferably made of high-strength steel of the same material as the main bearing plate 2. Its tensile strength is ≥1800Mpa, yield strength is ≥1200Mpa, elongation is ≥10%, and its thickness H1 is 20-30mm.

[0097] See also Fig. 9 The heating wire 6 is made of copper with good heat transfer effect. Its main function is to heat the main bearing plate 2 and transfer the heat to the wedge block and the formed part 7 through heat transfer. Then the temperature gradient of the part is reduced, the internal stress is reduced, the deformation of the part is further suppressed, and the risk of cracking is reduced.

[0098] See also Fig.10 The fixing screw 8 is a top hexagon socket screw, which is easy to disassemble. The main function is to fix the main bearing plate 2 and the loading platform 1 to the motion mechanism.

[0099] The present invention also provides a forming method for printing high-stress materials, which is used to suppress cracking.

[0100] See also Figures 11 to 14 , taking the forming of a full-width TC4 titanium alloy cross part as an example to illustrate.

[0101] Considering the structural characteristics of the part, vertical forming with the cross surface as the bottom surface can reduce support. However, the cross part is very large and occupies the entire substrate area. Therefore, the additive manufacturing software SimufactAdditive is used to simulate its deformation and stress. The maximum deformation, maximum stress, stress distribution and deformation distribution are calculated. According to the common sense of laser selective melting forming, the maximum stress distribution is at the bottom of the cross part 7 where it contacts the substrate. It is also the part 7 that is most likely to crack. Therefore, a scheme design is carried out for the cross part 7.

[0102] The design of cross part 7 is as follows Fig.12 , 13 As shown, a design margin C1 of 5 to 10 mm is added to the bottom of the cross part (which is directly connected to the wedge block of the same material as above), and a wedge groove 71 is opened at the margin position, and the height C2 of the wedge groove 71 is defined, and C1-C2≥2 mm is satisfied. The groove width b is 1 to 50 mm, and the wedge groove 71 is just above the gap position on the four sides of the wedge block above, and the groove width is greater than the gap width. The angle α between the wedge groove and the horizontal plane is 40 to 85°.

[0103] The main purpose of providing the wedge-shaped groove 71 is to disperse the size of the excess part at the bottom of the cross part 7, forming a plurality of smaller feet, which effectively reduces stress concentration. When the bottom of the cross part 7 shrinks and deforms, the small feet separated by the wedge-shaped groove at the bottom first shrink inward. The cross part 7 is not directly connected to the wedge block, and each foot is basically connected to a wedge block. In this way, the large shrinkage deformation of the cross part 7 is transmitted to the wedge block through the foot. Then the wedge block is driven to slide along the dovetail groove of the main bearing plate. Through its sliding, the huge internal energy inside the cross part 7 is absorbed, and the stress is effectively released, which not only reduces the deformation of the cross part 7, but also effectively suppresses its cracking risk. Moreover, the stress is transmitted to the main bearing plate 2 through the wedge block. Since the structural strength of the main bearing plate 2 is much greater than the formed part 7 itself, the deformation of the part 7 can be effectively reduced.

[0104] In this way, the purpose of controlling the shape of large-sized parts and inhibiting their cracking is achieved by using a high-strength thin substrate (main bearing plate 2) of different materials and superimposing a small-sized removable and replaceable substrate (wedge block) of the same material. More importantly, the original use of the same material thick substrate with low strength and high processing difficulty is greatly reduced, and the need for reprocessing each time it is used. When forming parts close to the height of the forming bin of the laser selective melting forming equipment, it is a huge pain point that thick substrates cannot be used. Moreover, the wedge block is movable and can be selected according to the characteristics of the parts. The wedge blocks are of various types and sizes. The grooves of the wedge blocks of the main bearing plate can be made into a variety of bite-able forms such as dovetail, Tai Chi, and 8-shaped. And the layout of the depressions can be selectively processed according to the distribution of the parts on the substrate, which can be either horizontal and vertical staggered, or X-shaped, diamond, triangular, or circular. The main bearing plate can be completely grooved according to the cross-sectional shape and size of the bottom of the part forming, so there is no need to open the grooves on the full width, which greatly reduces the processing workload and improves the processing efficiency. The main bearing plate has higher structural strength and the thickness can be further reduced.

[0105] The schematic diagram of forming the cross part 7 is as follows Fig.14 , 15 As shown, during the forming process, the contraction deformation of the cross part 7 along the long side of the base plate is transmitted to the long side wedge block through the bottom foot, so that it slides inward along the long side along the dovetail groove of the main bearing plate 2, and at the same time, it is slightly deformed upward along the normal vector of the main bearing plate 2 because of the matching clearance between it and the dovetail groove. During the forming process, the contraction deformation of the cross part 7 along the short side of the base plate is transmitted to the segment side wedge block through the bottom foot, so that it slides inward along the short side along the dovetail groove of the main bearing plate, and at the same time, it is slightly deformed upward along the normal vector of the main bearing plate 2 because of the matching clearance between it and the dovetail groove.

[0106] from Fig.14 It can be clearly seen that the wedge groove of the cross piece is just above the clearance fit of the wedge block.

[0107] See also Fig.15 In this embodiment, only a wedge block is added to the bottom of the cross part 7, which can effectively reduce the assembly amount of the wedge block. At the same time, in order to prevent the wedge block from sliding freely, positioning pins 9 are designed on both sides of the wedge block for positioning. The positioning pins 9 do not directly contact the wedge block, but maintain a certain distance K, and the value of K is 0.2-1mm. In this way, the free movement characteristics of the wedge block can be fully utilized.

[0108] After using the additive manufacturing software SimufactAdditive to simulate the deformation and stress of the cross parts, the Figure 1 According to the layout of the cross parts in the main bearing plate, dovetail grooves are opened and wedge blocks of specific sizes are processed. Then the wedge blocks are matched according to the forming position of the cross parts in the main bearing plate (clearance fit), and the positioning pins 9 are used to limit them to prevent them from sliding freely.

[0109] Fix the assembled main bearing plate 2 to the stage 1 (with the heating wire 6 embedded) by fixing screws. The screws are in a loose state. Turn on the heating wire to heat the main bearing plate 2 at a temperature of 200-500°C, and tighten the heating plate. Close the 3D printer door and run the scraper to spread the powder. Until the powder completely buries the wedge block, only 0-0.06mm thick powder is formed on its upper surface.

[0110] The cross part 7 ( Fig.12 As shown in the figure), the laser selective melting forming professional software is used for slicing, and the sintering parameters are assigned to generate the printing program.

[0111] The printing program is transferred into the printing device, and the oxygen content is inflated until it is less than 0.1%, and the printing program is run, and the laser emits light for printing. After each layer is printed, the main load-bearing platform drops a layer thickness, the scraper spreads the powder, and the laser emits light for sintering, and this cycle is repeated until the cross part 7 is formed.

[0112] As the forming height of part 7 increases, the stress and shrinkage deformation of the part gradually increase, and its bottom foot gradually shrinks inward, thereby driving the wedge block to slide inward along the dovetail of the main bearing plate. Because the height of the parts is stacked layer by layer, although there is a large gap between each wedge block and between it and the dovetail groove of the main bearing plate 2. However, the deformation of each layer is very small, and the wedge block will not obviously protrude from the powder spreading plane and affect the scraper powder spreading, thereby ensuring the continuity of printing.

[0113] After the forming is completed, the heating wire stops heating and the temperature begins to drop. The cross part 7 and the wedge are different in size and shrink and deform differently. Because there is a gap between the wedge block and the dovetail groove of the main bearing plate 2, it can achieve good deformation coordination with the cross part 7 during cooling, effectively reducing the risk of cooling cracking. Then open the hatch to remove the fixing screws 8, and remove the part 7 together with the main bearing plate 2 and the wedge.

[0114] Then, according to the material of the cross part 7, vacuum heat treatment is used for annealing. The stress of the cross part 7 is further released, and the stress of the wedge block and the main bearing plate 2 is also released. Since the wedge block and the main bearing plate 2 have clearance fit, most of the deformation is compensated by the clearance, and the main bearing plate has extremely high strength, the main bearing plate 2 will not have obvious deformation.

[0115] The cross part 7 is cut off from the wedge block by wire cutting, and then the wedge block is removed from the main bearing plate.

[0116] The main bearing plate 2 is inspected for flatness. If the flatness is greater than 0.06 mm, it is ground. It can be recycled. Check the smoothness of the wedge block and the dovetail groove (wedge groove) of the main bearing plate 2. If it is stuck, the dovetail groove of the main bearing plate 2, the dovetail boss of the wedge block, and the top plane of the wedge block are reprocessed. In this way, the composite reinforced substrate can be reused.

[0117] The beneficial effects of implementing a high stress material printed composite substrate and forming method provided by the present invention are:

[0118] A stage is provided, a main bearing plate is provided on the stage, staggered wedge grooves are provided on the main bearing plate, wedge blocks for supporting parts are installed in the wedge grooves, and active gaps for dispersing stress are reserved between the wedge blocks. If the part shrinks along the short side of the main bearing plate, because the part does not contact the main bearing plate but directly contacts the wedge blocks, there is a gap between the wedge blocks and the wedge grooves of the main bearing plate, and there is also a gap between each other. The wedge blocks slide along the direction of the wedge grooves and deform slightly along the normal vector direction of the main bearing plate. If the shrinkage of the part is large, the wedge blocks will approach each other, and the gap between them can effectively resist the shrinkage and deformation of the part. In this way, the huge internal energy generated by the forming stress of the part is effectively absorbed through the effective movement of the wedge blocks, reducing the risk of deformation and cracking of the part, and solving the technical problem that the substrate of large-size products formed by laser selective melting is difficult to match, resulting in substrate deformation, tearing and product stress cracking.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high stress material printing composite substrate, characterized in that: The invention comprises a loading platform (1), wherein a main bearing plate (2) is arranged on the loading platform (1), wherein the main bearing plate (2) is provided with staggered wedge-shaped grooves, wherein wedge-shaped blocks for supporting parts (7) are installed in the wedge-shaped grooves, and movable gaps are reserved between the wedge-shaped blocks for dispersing stress through coordinated movement and deformation of the wedge-shaped blocks; the wedge-shaped blocks comprise four-corner wedge-shaped blocks (3) arranged at the four corners of the main bearing plate (2), and four-side wedge-shaped blocks (4) arranged at the four sides of the main bearing plate (2); large-sized first bosses (33) are arranged at intervals on the short sides of the main bearing plate (2), and small-sized second bosses (34) are arranged at intervals on the long sides of the main bearing plate (2); first wedge-shaped grooves are formed between the first bosses (33), and second wedge-shaped grooves are formed between the second bosses (34), and the number of the first wedge-shaped grooves is less than the number of the second wedge-shaped grooves; The wedge block also includes a patch wedge block (5) arranged in the middle of the main bearing plate (2); a heating groove (11) is arranged on the top of the loading platform (1), and a heating wire (6) is embedded in the heating groove (11); the main bearing plate (2) and the loading platform (1) are respectively provided with a first screw hole (21) and a second screw hole (12) for fastening connection through fixing screws (8); the main bearing plate (2) is also provided with a pin hole (22), and a positioning pin (9) is arranged in the pin hole (22) for limiting the free sliding of the wedge block; the bottom of the wedge block is a dovetail protrusion, the upper part is a square, and the top is a rough plane; the wedge groove is a dovetail groove; the main bearing plate (2) and the loading platform (1) are made of the same material, and the wedge block is made of the same material as the part (7), and the part (7) is cross-shaped.

2. A method for printing and forming high stress materials, characterized in that: Printing a composite substrate based on a high stress material according to claim 1 includes the following method: Using additive manufacturing software, the deformation and stress of the part (7) are simulated to calculate the maximum deformation, maximum stress, stress distribution and deformation distribution; Add a design allowance to the bottom of part (7); A wedge-shaped groove (71) is provided at the margin portion; The margin portion corresponds to the wedge block, and the groove width of the wedge groove (71) is larger than the active gap; If the wedge-shaped block does not completely cover the main bearing plate (2), positioning pins (9) are set on both sides of the wedge-shaped block to limit the position; The main bearing plate (2) is fixed to the loading platform (1) by means of fixing screws (8); The heating wire (6) in the stage (1) is turned on to heat the main bearing plate (2) at a temperature of 200 to 500° C. At this time, the fixing screws (8) at the four corners are tightened to fix the main bearing plate (2); Close the door of the 3D printer and use the scraper to spread the powder until the powder completely buries the wedge-shaped block and forms a powder with a thickness of 0 to 0.06 mm on its upper surface; The designed part (7) is sliced ​​by laser selective melting forming professional software, and sintering parameters are assigned to generate a printing program; The printing program is transferred into the printing device, and the air is inflated until the oxygen content is less than 0.1%, and then the printing program is run, and the laser emits light for printing; After each layer is printed, the main bearing platform is lowered by one layer thickness, a scraper spreads the powder, and the laser emits light for sintering, and this cycle is repeated until the cross part (7) is formed; After the forming of the part (7) is completed, the heating wire (6) stops heating and waits for the temperature to drop to a predetermined temperature; Open the hatch, remove the fixing screws (8), and remove the component (7) together with the main bearing plate (2) and the wedge block; The part (7) is cut off from the wedge block by wire cutting, and then the wedge block is removed from the main bearing plate (2).

3. A high stress material printing forming method according to claim 2, characterized in that: The main bearing plate (2) is inspected for flatness. If the flatness is greater than 0.06 mm, grinding is performed. The smoothness of the cooperation between the wedge block and the wedge groove of the main bearing plate (2) is checked. If jamming occurs, the wedge groove and the wedge block of the main bearing plate (2) are reprocessed.

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