SLM additive manufacturing T-shaped tubular joint printing process optimization and manufacturing method

Abstract

The invention relates to an SLM additive manufacturing T-shaped tubular joint printing process optimization and manufacturing method, a T-shaped tubular joint is formed by intersecting and connecting two steel pipes of the same or different types, the T-shaped tubular joint comprises an orthogonal T-shaped tubular joint and an oblique T-shaped tubular joint, and the method comprises the steps that composition and printing parameters of a tubular joint printing device are configured; optimizing an edge structure and a suspension structure of the tubular joint; optimizing the suspension angle and the horizontal included angle of the tubular joint; and optimizing the T-shaped tubular joint support configuration. The laser fusion printing device has the beneficial effects that based on the laser fusion printing device and parameter setting, optimization, manufacturability and integrated forming of a structure model are achieved through edge structure optimization and suspension structure optimization, internal support-free printing is achieved through suspension angle optimization and horizontal included angle optimization, and the printing collision condition is avoided; and the printing forming success rate of the T-shaped steel pipe tubular joint is effectively increased.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and more specifically, it relates to the printing process optimization and manufacturing method of SLM additive manufacturing of T-shaped intersecting nodes. Background Art

[0002] With the continuous progress of modern intelligent construction technology, Selective Laser Melting (SLM) technology, as a typical manufacturing process in the field of metal 3D printing, is particularly suitable for applications in fields such as complex steel nodes with spatial structures due to its characteristics of high precision, high strength, and strong structural integrity forming.

[0003] The SLM technology melts metal powder through a laser heat source and stacks it layer by layer to form complex metal structural parts. However, the forming quality of SLM additive manufacturing of metal structural parts is affected by many factors such as the printing layer thickness, the rationality of the printed structure, the overall placement of the structure, and the structure support configuration. It is necessary to reasonably optimize and configure the printing parameters according to the actual printing situation. T-shaped steel pipe intersecting nodes are widely used in the node connections of spatial structures. In the past, they were generally connected by welding seams, but due to the lack of structural integrity, problems such as weld tearing are likely to occur. And integral casting has disadvantages such as high cost and complex mold opening. Therefore, it is necessary to propose a new manufacturing method with high efficiency and high precision. The SLM additive manufacturing technology can realize the integrated printing and forming of T-shaped steel pipe intersecting nodes, but there are still defects that a large number of additional supports need to be set due to the overhang effect of the small-inclination steel pipe wall, resulting in material waste, affecting the printing progress, and difficult support removal after forming. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the prior art and propose a printing process optimization and manufacturing method for SLM additive manufacturing of T-shaped intersecting nodes.

[0005] In the first aspect, there is provided a printing process optimization and manufacturing method for SLM additive manufacturing of T-shaped intersecting nodes. The T-shaped intersecting nodes are composed of two identical or different types of steel pipes intersecting and connecting with each other, including orthogonal T-shaped intersecting nodes and skew T-shaped intersecting nodes. The method includes:

[0006] S1. Configuration of parameters of the T-shaped intersecting node printing device: Configure the composition and printing parameters of the intersecting node printing device;

[0007] S2. Optimization of the T-shaped intersecting node structure model: Optimize the edge structure and overhang structure of the intersecting node;

[0008] S3. Optimization of the T-shaped intersecting node placement mode: Optimize the overhang angle and horizontal included angle of the intersecting node;

[0009] S4. Optimization of the support configuration of the T-shaped tubular joint: Adjust the support height, set the support density, and construct the support platform of the tubular joint to obtain the geometric model of the T-shaped tubular joint with a support frame after process optimization.

[0010] Preferably, S1 includes:

[0011] S11. Composition of the tubular joint printing device: Use a laser melting printing device including a precision optical system 1, a melting control system 2, a motion forming system 3, a powder feeding structure system 4, and a gas protection system 5 to directly manufacture metal structural parts based on three-dimensional data; the printing raw material is a metal powder material, and the metal powder material includes stainless steel, titanium alloy, and aluminum alloy.

[0012] S12. Setting of the tubular joint printing parameters: Control the performance index parameters of the metal powder and the process parameters of the forming process. The process parameters include printing layer thickness, preheating temperature, laser power, supply voltage, working pressure, and working gas consumption.

[0013] Preferably, S2 includes:

[0014] S21. Optimization of the edge structure of the tubular joint: Optimize the arc chamfer at the junction of the main and branch pipes and at the edge of the main and branch pipe lines, and optimize the bevel angle of the rib plate at the end of the branch pipe.

[0015] S22. Optimization of the overhang structure of the tubular joint: Process the internal stiffening plate at the end of the joint separately to reduce the overhang and local deformation inside the relevant tubular joint.

[0016] The overhang structure of the tubular joint includes the overhang at the intersection of the main and branch pipes, the overhang of the external stiffening plate at the end of the joint, and the overhang of the internal stiffening plate at the end of the joint; the overhang at the intersection of the main and branch pipes is optimized through S3, and the overhang of the external stiffening plate at the end of the joint is optimized through S4.

[0017] Preferably, S3 includes:

[0018] S31. Optimization of the overhang angle of the tubular joint: Adopt a printing scheme with a preset upward angle of the main pipe, so that the angle between the branch pipe and the horizontal plane is not less than the preset angle, and realize the support-free printing inside the structure of the T-shaped tubular joint.

[0019] S32. Optimization of the horizontal angle of the tubular joint: Place the tubular joint at a preset upward angle along the direction of the scraper travel, and deflect it at a preset deflection angle along the direction of the scraper travel in the horizontal plane to avoid excessive collision between the scraper and the formed structure.

[0020] Preferably, S4 includes:

[0021] S41. Adjusting the support height of the intersecting node: Use a block-shaped grid structure to support the intersecting node, and set a fine-tooth structure at the intersection of the grid structure and the intersecting node to facilitate the removal of the support after the structure is formed; Set up a support platform to reduce the support height and the direct generation of the support on the node surface;

[0022] S42. Setting the support density: Adjust the filling line interval and the support gap; Use the method of small-grid block-shaped support to arrange the printing support for the upper part of the structure in the middle and late stages of printing, and use the method of regenerative grid block-shaped support to arrange the printing support for the lower part of the structure in the initial stage of printing;

[0023] S43. Constructing the support platform: Build a hollow grid support platform for the main pipe and branch pipes through parametric modeling to eliminate the internal deformation of the T-shaped intersecting node caused by the overall self-weight;

[0024] Set a platform plate with a preset upward inclination angle parallel to the surface of the main pipe at the bottom of the main pipe to support the main pipe, and print a hollow grid bracket to support the platform plate with a preset upward inclination angle; The platform plate and the hollow grid bracket form the hollow grid support platform of the main pipe; The hollow grid bracket considers the overhang constraint and is built by a series of rods with a preset inclination angle for unsupported printing;

[0025] The upper structure of the branch pipe support platform is supported by a platform plate with a preset upward inclination angle parallel to the branch pipe and a hollow grid bracket; The lower structure of the branch pipe support platform transmits the support frame above the upper surface of the main pipe to the substrate by building a bridge above the main pipe; The upper structure of the branch pipe support platform and the lower structure of the branch pipe support platform form the hollow grid support platform of the branch pipe.

[0026] In the second aspect, a method for printing and manufacturing a T-shaped intersecting node by SLM additive manufacturing is provided, including:

[0027] S1. Use 3D modeling software to perform parametric modeling and structural model optimization to obtain the geometric model of the T-shaped intersecting node described in any one of the first aspects;

[0028] S2. Convert the geometric model of the T-shaped intersecting node into an STL format file, and perform inclination placement and support frame addition;

[0029] S3. Perform layer slicing on the geometric model of the T-shaped intersecting node with a support frame after process optimization to obtain a planned path suitable for 3D printing;

[0030] S4. Determine the printing scheme for the node model through multiple rounds of printing tests;

[0031] S5. Use a laser melting printing device to perform 3D printing and manufacturing, and obtain a T-shaped intersecting node after removing the additional support of the formed part.

[0032] Preferably, the steel pipe forms of the T-shaped tubular joints include circular pipes, elliptical pipes, square pipes, and rectangular pipes. The T-shaped tubular joints include circular pipe T-shaped tubular joints, elliptical pipe T-shaped tubular joints, square pipe T-shaped tubular joints, rectangular pipe T-shaped tubular joints, and hybrid T-shaped tubular joints.

[0033] In a third aspect, an optimization system for the SLM additive manufacturing process of T-shaped tubular joints is provided, which is used to execute the method described in any one of the first aspects. The T-shaped tubular joint is composed of the intersection and penetration connection of two identical or different types of steel pipes. The system includes:

[0034] A configuration module for configuring the parameters of the T-shaped tubular joint printing device: configuring the composition and printing parameters of the tubular joint printing device;

[0035] A first optimization module for optimizing the structural model of the T-shaped tubular joint: optimizing the edge structure and overhang structure of the tubular joint;

[0036] A second optimization module for optimizing the placement mode of the T-shaped tubular joint: optimizing the overhang angle and horizontal included angle of the tubular joint;

[0037] A third optimization module for optimizing the support configuration of the T-shaped tubular joint: adjusting the support height, setting the support density, and constructing the support platform of the tubular joint to obtain a geometric model of the T-shaped tubular joint with a support frame after process optimization.

[0038] In a fourth aspect, a computer storage medium is provided. The computer storage medium stores a computer program; when the computer program runs on a computer, the computer is enabled to execute the method described in any one of the first aspects.

[0039] In a fifth aspect, an electronic device is provided, including:

[0040] A memory for storing a computer program;

[0041] A processor for executing the computer program to implement the method described in any one of the first aspects.

[0042] The beneficial effects of the present invention are as follows:

[0043] 1. The SLM additive manufacturing process optimization and manufacturing method for T-shaped tubular joints provided by the present invention, based on the laser melting printing device and parameter settings, realizes the optimization, manufacturability, and integrated forming of the structural model through the optimization of the edge structure and overhang structure, and realizes the printing without internal support and avoids printing collision through the optimization of the overhang angle and horizontal included angle, effectively improving the printing success rate of T-shaped steel pipe tubular joints.

[0044] 2. The optimized SLM additive manufacturing process and manufacturing method for T-shaped intersecting joints provided by the present invention avoid warping at the edges of the printed structure by setting the support height and density of the joints, and achieve the minimum support area and improve the surface forming quality of the joints through the construction of the support platform, realizing the structural integration, wall surface without support, and high-precision printing and forming manufacturing of T-shaped steel pipe intersecting joints in application scenarios such as laser additive manufacturing of large-sized spatial structure complex joints.

[0045] 3. The optimized SLM additive manufacturing process and manufacturing method for T-shaped intersecting joints provided by the present invention are applicable to orthogonal T-shaped intersecting joints (β = 0°) and skew T-shaped intersecting joints (β ≠ 0°) through the setting of the printing scheme with the main pipe inclined upward at 45°, realizing printing without restrictions on the included angle between the main and branch pipes and without support on the wall surface; through the construction of the support platform, the internal deformation caused by the overall self-weight of the T-shaped intersecting joint is eliminated, realizing 3D printing of T-shaped intersecting joints with large dimensions (the diameter of the main pipe is not less than 50 mm). BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic diagram of the overall steps of the optimized SLM additive manufacturing process and manufacturing method for T-shaped intersecting joints of the present invention;

[0047] Figure 2a is a schematic diagram of an orthogonal T-shaped intersecting joint (β = 0°);

[0048] Figure 2b is a schematic diagram of a skew T-shaped intersecting joint (β ≠ 0°);

[0049] Figure 3 is a schematic diagram of the composition of a laser melting printing device;

[0050] Figure 4a is a schematic diagram of the optimization of the arc chamfer at the junction of the main and branch pipes;

[0051] Figure 4b is a schematic diagram of the optimization of the arc chamfer at the edge of the main and branch pipes;

[0052] Figure 4c is a schematic diagram of the optimization of the bevel angle of the rib plate at the end of the branch pipe;

[0053] Figure 5 is a schematic diagram of the integrated optimization printing scheme of the internal stiffening plate;

[0054] Figure 6 is a schematic diagram of the printing support scheme with different vertical placement angles;

[0055] Figure 7a is a schematic diagram of the printing scheme of an orthogonal T-shaped intersecting joint with the main pipe inclined upward at 45°;

[0056] Figure 7bIt is a schematic diagram of the printing scheme for the skew T-shaped intersecting node with the main pipe inclined upward at 45°;

[0057] Figure 8 It is a schematic diagram of the printing scheme with a small-angle deflection placement in the horizontal plane;

[0058] Figure 9 It is a schematic diagram of edge warping caused by too high support height;

[0059] Figure 10a It is a schematic diagram of the printing scheme with conventional density grid support;

[0060] Figure 10b It is a schematic diagram of the printing scheme with encrypted strategy grid support;

[0061] Figure 10c It is a schematic diagram of the printing scheme with regenerative grid support;

[0062] Figure 11 It is a schematic diagram of the overall structure of the main pipe support platform;

[0063] Figure 12a It is a schematic diagram of the upper structure of the branch pipe support platform;

[0064] Figure 12b It is a schematic diagram of the lower structure of the branch pipe support platform;

[0065] Figure 12c It is a schematic diagram of the overall structure of the branch pipe support platform;

[0066] Figure 13 It is a specific flowchart for the optimized printing and manufacturing of the T-shaped intersecting node;

[0067] Figure 14a It is a schematic diagram of the printed physical object of the circular pipe T-shaped intersecting node;

[0068] Figure 14b It is a schematic diagram of the printed physical object of the square pipe T-shaped intersecting node;

[0069] Explanation of reference numerals: 1 - Precision optical system; 2 - Melting control system; 3 - Motion forming system; 4 - Powder supply mechanism system; 5 - Gas protection system. Detailed implementation manners

[0070] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0071] Embodiment 1:

[0072] To solve the problems of the existing technology, it is very necessary to research an optimized printing process and manufacturing method for SLM additive manufacturing of T-shaped intersecting joints, so as to achieve the integrated structure, unsupported wall surface and high-precision printing and forming manufacturing of T-shaped steel pipe intersecting joints in application scenarios such as laser additive manufacturing of large-size space structure complex joints.

[0073] In this regard, Embodiment 1 of the present application provides an optimized method for the SLM additive manufacturing T-shaped intersecting joint printing process, as Figures 2a to 2b shown, the T-shaped intersecting joint is composed of two identical or different types of steel pipes intersecting and connecting with each other. The types of steel pipes include circular pipes, elliptical pipes, square pipes and rectangular pipes. The specific forms of T-shaped intersecting joints include circular pipe T-shaped intersecting joints, square pipe T-shaped intersecting joints, etc.; the steel pipe intersection angle range of the T-shaped intersecting joint is β = 0 to 180°, which is divided into orthogonal T-shaped intersecting joints (β = 0°, Figure 2a ), skewed T-shaped intersecting joints (β ≠ 0°, Figure 2b ).

[0074] Specifically, as Figure 1 shown, the method includes:

[0075] S1. Configuration of parameters of the T-shaped intersecting joint printing device: Configure the composition and printing parameters of the intersecting joint printing device.

[0076] S1 includes:

[0077] As Figure 3 shown, S11. Composition of the intersecting joint printing device: Use a laser melting printing device including a precision optical system 1, a melting control system 2, a motion forming system 3, a powder feeding structure system 4 and a gas protection system 5 to directly manufacture metal structural parts based on three-dimensional data; the printing raw material is metal powder material, and the metal powder material includes stainless steel, titanium alloy and aluminum alloy.

[0078] Specifically, the printing and manufacturing of the T-shaped intersecting joint is carried out in the forming chamber of the printing device. The powder scraping mechanism is coordinated by a servo motor with a high-precision guide rail and a synchronous belt drive to ensure the flatness of the scraper during the powder scraping process; the Z-axis lifting mechanism and the powder feeding mechanism are driven by a servo motor and coordinated with a high-precision lead screw guide rail to respectively achieve the motion accuracy of the metal structural part and the controllable metal powder feeding amount during the printing process; before printing and powder spreading, use an explosion-proof powder sieve to screen, stir and homogenize the metal powder, and use an inert gas protection system to control the oxygen content.

[0079] S12. Setting of intersecting joint printing parameters: Control the performance index parameters of the metal powder and the process parameters of the forming process. The process parameters include printing layer thickness, preheating temperature, laser power, power supply voltage, working pressure and working gas consumption.

[0080] In this embodiment, the performance index parameters of the metal powder are shown in Table 1, and the printing parameters in the forming process are shown in Table 2.

[0081] Table 1 Performance Index Parameters of Metal Powder

[0082]

[0083] Table 2 Printing Parameters in the SLM Forming Process

[0084]

[0085] S2. Optimization of the T-shaped pipe-joint node structure model: Optimize the edge structure and overhang structure of the pipe-joint node.

[0086] S2 includes:

[0087] S21. Optimization of the pipe-joint node edge structure: The edge structure optimization process includes the optimization of the arc chamfer at the junction of the main and branch pipes ( Figure 4a ), the optimization of the arc chamfer at the edge line of the main and branch pipes ( Figure 4b ), and the optimization of the bevel angle of the rib plate at the end of the branch pipe ( Figure 4c ).

[0088] For the structural printing layer with a large cross-sectional change, laser additive manufacturing is prone to large deformations and cause the failure of the overall structure printing; by optimizing the transition of the node edge structure, the geometric deformation of the T-shaped pipe-joint node becomes smoother and more continuous;

[0089] For the T-shaped pipe-joint node containing a circular pipe, there is only an arc chamfer at the junction of the main and branch pipes; for the T-shaped pipe-joint node containing a square pipe, it includes an arc chamfer at the junction of the main and branch pipes and an arc chamfer at the edge line of the main and branch pipes themselves; the radius R of the arc chamfer is taken as 2 times the wall thickness t1 of the branch pipe, that is, R = 2t1; the arc chamfer parts at the edge structure of the T-shaped pipe-joint node and the two-sided main branch pipe walls are fitted together so that it can rely on the two-sided main branch pipe walls to produce continuous changes during the printing process; the additional stiffening rib plates at the end of the T-shaped pipe-joint node are processed with bevel angles to avoid sudden changes in the printing cross-section at the end plate and ensure the printing success rate.

[0090] S22. Optimization of the pipe-joint node overhang structure: The internal stiffening plate at the end of the node is processed separately to reduce the overhang and local deformation inside the relevant pipe-joint node.

[0091] The overhang structure optimization includes the overhang caused by the perpendicularity of the main and branch pipes, the overhang of the additional stiffening plate at the end of the node, and the overhang of the internal stiffening plate at the end of the node. As Figure 5As shown in the figure, for the T-shaped tubular joint structure, in addition to the overhang caused by the perpendicularity between the main pipe and the branch pipe, the main overhang is generated by the internal stiffening plate at the end of the joint; the internal stiffening plate part brings a relatively large local overhang section to the overall structure, and due to its location inside the joint, a large number of support structures will inevitably be generated inside the joint, which is not conducive to the removal of the later support; at the same time, the process of printing the internal stiffening plate will cause the associated bulging deformation of the connected pipe wall, which is not conducive to the uniformity of the pipe wall thickness of the joint; after specific printing verification, the internal stiffening plate is taken out for separate processing, so as to reduce the overhang and local deformation inside the tubular joint; in this embodiment, the internal stiffening plate is separately printed and then spot-welded to the main and branch pipe structures, and the external stiffening plate is printed integrally.

[0092] S3. Optimization of the placement mode of the T-shaped tubular joint: Optimize the overhang angle and horizontal included angle of the tubular joint.

[0093] S3 includes:

[0094] S31. Optimization of the overhang angle of the tubular joint: Adopt a printing scheme with the main pipe preset at an upward inclination angle, so that the included angle between the branch pipe and the horizontal plane is not less than the preset angle, and realize the support-free printing inside the structure of the T-shaped tubular joint.

[0095] As Figure 6 shown, the laser additive manufacturing process generally considers whether to add support with the overhang angle of 45° as the boundary; through the comparison of the simulation and test results of different printing angles α = -45°, 0°, 45°, the considered factors include the Z-axis height, support area, XY projection, etc. The support areas of the printing schemes with the main pipe vertical at 90° and the main pipe inclined upward at α = 45° are relatively small, the Z-axis height is moderate, and the spatial layout is reasonable; through experimental verification, the warping phenomenon is obvious at the edge of the printing scheme with the main pipe vertical at 90°, and the printing scheme with the main pipe inclined upward at the preset angle α = 45° is selected as the actual printing scheme; through the internal adjustment of the structure and the optimization of the overhang angle, the support-free printing inside the structure of the T-shaped tubular joint is realized.

[0096] As Figures 7a to 7b shown, the printing scheme with the main pipe inclined upward at α = 45° is applicable to the orthogonal T-shaped tubular joint (α = 0°, Figure 7a ) and the skew T-shaped tubular joint (α ≠ 0°, Figure 7b ); by changing the direction of the main pipe, it can be ensured that the included angle between the branch pipe and the horizontal plane in the printing scheme with the main pipe inclined upward at α = 45° is not less than 45°; realize the printing without support for the unlimited included angle between the main and branch pipes and the wall surface.

[0097] S32. Optimization of the horizontal included angle of the tubular joint: Place the tubular joint at a preset upward inclination angle along the direction of the blade travel, and deflect it at a preset deflection angle along the blade direction in the horizontal plane to avoid excessive collision between the blade and the formed structure.

[0098] Exemplarily, as Figure 8 shown, place the intersecting node obliquely upward at an angle of α = 45° along the main pipe in the direction of the scraper travel, and make a small-angle deflection of 5 - 10° in the horizontal plane to avoid large-area contact between the scraper and the formed part of the structure during the powder scraping process.

[0099] During the printing process, the angle between the printing scraper and the metal structure has a significant impact on the printing success rate. The collision between the scraper and the formed part of the structure will cause printing failure; use a soft rubber scraper, place the intersecting node obliquely upward at an angle of α = 45° along the main pipe in the direction of the scraper travel, and make a small-angle rotation offset of θ = 5 - 10° in the horizontal plane to avoid large-area contact between the scraper and the formed part of the structure during the powder scraping process and increase the printing success rate.

[0100] S4. Optimization of the support configuration of the T-shaped intersecting node: Adjust the support height of the intersecting node, set the support density, and construct the support platform to obtain the geometric model of the T-shaped intersecting node with a support frame after process optimization.

[0101] S4 includes:

[0102] S41. Adjustment of the support height of the intersecting node: Use a block grid structure to support the intersecting node, and set a fine-tooth structure at the intersection of the grid structure and the intersecting node to facilitate the removal of the support after the structure is formed; set a support platform to reduce the support height to avoid edge warping, and at the same time reduce the direct generation of the support on the node surface to improve the surface forming quality of the node.

[0103] As Figure 9 shown, use a block grid structure with appropriate size and spacing to support the intersecting node, and ensure the smooth removal of the support during post-processing through a fine-tooth structure at the intersection of the grid structure and the intersecting node; during actual printing, if the support height is too high, it is easy to have a large end offset during the scraper travel, that is, it shows as boundary warping, resulting in support failure. Therefore, it is necessary to reduce the support height; in this embodiment, the support height is controlled within 100 mm, and it is not easy to have the boundary warping phenomenon.

[0104] Reducing the support height by directly changing the angle will cause an increase in the overhang angle or an increase in internal supports. Therefore, the support height is reduced by building a support platform; when there is an overlapping part in the projection area of the node on the printing plane, a support surface will be generated on the surface of the lower node, affecting the surface forming quality of the node. Using the support platform can reduce the direct generation of the support on the node surface, thereby improving the surface forming quality of the node.

[0105] S42. Setting of the support density: Adjust the filling line interval and the support gap; use a small-grid block support and a regenerative grid method to arrange the printing support.

[0106] It should be noted that the selection of support density will affect the strength of the support itself and the difficulty of removing the support during post-processing. Appropriate infill line spacing and support gaps should be selected to ensure the smooth printing of metal structural parts.

[0107] In addition, due to the different positions of the support settings, the strength requirements for the support will also vary. At the initial stage of node printing, the support between the node and the substrate needs to have a relatively high strength because it needs to conform to the cross-sectional mutation of the structural part. Comparing the strength and ease of removal during post-processing of conventional density grid supports ( Figure 10a ), encrypted strategy grid supports ( Figure 10b ), and regenerative grid supports ( Figure 10c ).

[0108] After testing, small grid block supports with a size of 4×4×4 can meet the printing support requirements for the upper part of the structure during the middle and late stages of printing. However, for the support between the initial printing node and the substrate, a higher strength is required. The regenerative grid block support can better meet the printing needs and is conducive to removal during post-processing; although the encrypted grid block support has a higher strength, it is more difficult to remove during post-processing. Finally, it is decided to use small grid block supports and regenerative grids for printing support layout and select according to the specific situation during the actual printing process.

[0109] S43. Support platform construction: Build a hollow grid support platform for the main pipe and branch pipes through parametric modeling to eliminate the internal deformation of the T-shaped intersecting node caused by the overall self-weight and realize the 3D printing of large-size T-shaped intersecting nodes. Large-size means that the diameter of the corresponding main pipe is not less than 50 mm.

[0110] As Figure 11 shown, (1) The construction of the main pipe support platform includes:

[0111] A support platform is established to reduce the support height and the support area on the node surface. The support platform needs to have sufficient contact area with the substrate and should not bring additional support to the node surface. The main pipe support is carried out by setting a platform plate inclined upward at 45° parallel to the node surface at the bottom of the node. The hollow grid bracket is printed to support the platform plate inclined upward at 45°. The hollow grid bracket is printed without support considering the printing overhang angle constraint, and inclined 45° rods are used to build the hollow grid bracket. In this embodiment, through experimental verification, the printing effect of the hollow structure is good.

[0112] The support platform is built through parametric modeling. A thin rod with a length of 5 mm and an outer diameter of 1 mm is used to form the basic unit. The basic unit consists of 8 rods inclined outward at 45°, and the support platform is built by arraying the unit cells in space. The built support platform can better meet the requirements of the SLM additive manufacturing process and save the consumption of printing supports, significantly improving the printing efficiency. The bracket formed by parametric modeling can flexibly adjust the size and gap according to different node sizes, so as to adapt to various printing scenarios.

[0113] As Figures 12a to 12c shown, (2) The construction of the branch pipe support platform includes:

[0114] The upper structure of the branch pipe support platform ( Figure 12a ) is supported by a platform plate inclined upward at 45° parallel to the branch pipe and a hollow grid bracket; if the lower structure of the branch pipe support platform ( Figure 12b ) is directly printed, rods will be generated on the upper surface of the main pipe. Therefore, a bridge is built above the main pipe through the "two - end bridging" method, making the upper surface of the main pipe suspended and transferring the original support surface located on the upper surface of the main pipe to the substrate; the upper structure of the branch pipe support platform and the lower structure of the branch pipe support platform form the overall structure of the branch pipe support platform ( Figure 12c ).

[0115] Support towers are generated from both ends of the main pipe through parametric modeling and gradually approach each other, and the bracket is bridged at the center line. To avoid the docking failure of the two - end support towers during the gradual inclination process before bridging due to excessive deformation, the butt - joint part of the support towers is "hooped" with a wall plate to ensure the overall continuity of the bracket part and the success of the final bracket bridging.

[0116] After the bridging is completed, the upper hollow grid bracket of the support platform docking is formed; the butt - joint part of the upper platform plate inclined upward at 45° and the hollow bracket is connected by an inverted triangular plate structure, so as to ensure a continuous and smooth transition of the cross - section at the connection part without cross - section mutation; the finally designed support platform system significantly saves printing materials compared with traditional printing supports, improves the printing efficiency; avoids the large - area generation of supports on the node surface, effectively improving the surface quality of the node; reduces the height of the direct support and ensures the success rate of the overall printing.

[0117] Embodiment 2:

[0118] Based on Embodiment 1, Embodiment 2 of the present application provides a method for printing and manufacturing a T - shaped intersecting node by SLM additive manufacturing, that is, the specific optimized printing process during actual printing, as Figure 13 shown, includes:

[0119] S1. Use 3D modeling software for parametric modeling and structural model optimization to obtain the geometric model of the T - shaped intersecting node;

[0120] S2. Convert the geometric model of the T-shaped tubular joint into an STL format file, and perform inclination placement and support frame addition.

[0121] S3. Perform layer slicing on the geometric model of the T-shaped tubular joint with a support frame after process optimization to obtain a planned path suitable for 3D printing.

[0122] S4. Determine the printing scheme for the joint model through multiple rounds of printing tests to achieve less support and a higher forming rate.

[0123] S5. Use a laser melting printing device to perform 3D printing manufacturing, and obtain a T-shaped tubular joint after removing the additional support of the formed part.

[0124] Among them, the T-shaped tubular joint includes a circular tube T-shaped tubular joint and a square tube T-shaped tubular joint. As Figures 14a to 14b shown, the above-mentioned SLM additive manufacturing T-shaped tubular joint printing process optimization and manufacturing method are applied to the structural integration, wall surface without support, and high-precision printing and forming manufacturing of T-shaped steel pipe joints in application scenarios such as laser additive manufacturing of large-sized space structure complex joints; specific printed physical applications include circular tube T-shaped tubular joints ( Figure 14a ), square tube T-shaped tubular joints ( Figure 14b ).

[0125] It should be noted that the same or similar parts in this embodiment and Embodiment 1 can be referred to each other, and will not be elaborated in this application.

[0126] Embodiment 3:

[0127] Based on Embodiment 1, Embodiment 3 of the present application provides an SLM additive manufacturing T-shaped tubular joint printing process optimization system. The T-shaped tubular joint is composed of two steel pipes of the same or different types intersecting and penetrating each other. The system includes:

[0128] A configuration module for configuring the parameters of the T-shaped tubular joint printing device: configuring the composition and printing parameters of the tubular joint printing device.

[0129] A first optimization module for optimizing the structural model of the T-shaped tubular joint: optimizing the edge structure and overhang structure of the tubular joint.

[0130] A second optimization module for optimizing the placement mode of the T-shaped tubular joint: optimizing the overhang angle and horizontal included angle of the tubular joint.

[0131] A third optimization module for optimizing the support configuration of the T-shaped tubular joint: adjusting the support height, setting the support density, and constructing a support platform for the tubular joint to obtain a geometric model of the T-shaped tubular joint with a support frame after process optimization.

[0132] It should be noted that the system provided in this embodiment is the system corresponding to the method provided in Embodiment 1. Therefore, for the parts that are the same or similar in this embodiment and Embodiment 1, reference can be made to each other and will not be elaborated in this application.

[0133] In summary, the SLM additive manufacturing T-shaped pipe joint printing process optimization and manufacturing method provided by the present invention, based on the laser melting printing device and parameter settings, realizes the optimization, manufacturability and integrated forming of the structural model through the optimization of the edge structure and the overhang structure; through the optimization of the overhang angle and the horizontal included angle, realizes printing without internal supports and avoids printing collision situations; through the setting of the node support height and density, avoids the warping of the printing structure edge; through the construction of the support platform, realizes the minimum support area and improves the surface forming quality of the node, and realizes the integrated structure, wall surface without support and high-precision printing and forming manufacturing of the T-shaped steel pipe joint in application scenarios such as laser additive manufacturing of large-size space structure complex nodes. And through actual verification, the method of the present invention is effective.

Claims

1. Optimization method for the printing process of T-shaped intersecting joints by SLM additive manufacturing, characterized in that, The T-shaped concrete-filled steel tubular (CFST) joints are composed of two identical or different types of steel pipes intersecting and connected by concrete-filled steel tubular joints, including orthogonal T-shaped CFST joints and skew T-shaped CFST joints. The method includes: S1. Parameter configuration of the T-shaped CFST joint printing device: Configure the composition and printing parameters of the CFST joint printing device; S2. Optimization of the T-shaped CFST joint structure model: Optimize the edge structure and overhang structure of the CFST joint; S3. Optimization of the T-shaped CFST joint placement mode: Optimize the overhang angle and horizontal included angle of the CFST joint; S4. Optimization of the T-shaped CFST joint support configuration: Adjust the support height, set the support density, and construct the support platform of the CFST joint to obtain the geometric model of the T-shaped CFST joint with a support frame after process optimization.

2. The method for optimizing the printing process of the SLM additive manufacturing T-shaped intersecting node according to claim 1, wherein S1 includes: S11. Composition of the CFST joint printing device: Use a laser melting printing device including a precision optical system 1, a melting control system 2, a motion forming system 3, a powder supply structure system 4, and a gas protection system 5 to directly manufacture metal structural parts based on three-dimensional data; the printing raw material is a metal powder material, and the metal powder material includes stainless steel, titanium alloy, and aluminum alloy; S12. Setting of the CFST joint printing parameters: Control the performance index parameters of the metal powder and the process parameters of the forming process. The process parameters include printing layer thickness, preheating temperature, laser power, supply voltage, working pressure, and working gas consumption.

3. The optimized method for SLM additive manufacturing of T-shaped intersecting node printing process according to claim 2, wherein S2 It includes: S21. Optimization of the CFST joint edge structure: Optimize the arc chamfer at the intersection of the main and branch pipes and at the edge of the main and branch pipe lines, and optimize the bevel angle of the rib plate at the end of the branch pipe; S22. Optimization of the CFST joint overhang structure: Individually process the internal stiffening plate at the end of the joint to reduce the overhang and local deformation inside the relevant CFST joint; The CFST joint overhang structure includes the overhang at the intersection of the main and branch pipes, the overhang of the external stiffening plate at the end of the joint, and the overhang of the internal stiffening plate at the end of the joint; the overhang at the intersection of the main and branch pipes is optimized through S3, and the overhang of the external stiffening plate at the end of the joint is optimized through S4.

4. The SLM additive manufacturing T-shaped intersecting node printing process optimization method according to claim 3, wherein S3 It includes: S31. Optimization of the CFST joint overhang angle: Adopt a printing scheme with a preset upward angle of the main pipe to make the included angle between the branch pipe and the horizontal plane not less than the preset angle, so as to realize the support-free printing inside the structure of the T-shaped CFST joint; S32. Optimization of the CFST joint horizontal included angle: Place the CFST joint obliquely upward at a preset angle along the direction of the scraper travel, and deflect it at a preset deflection angle along the direction of the scraper travel in the horizontal plane to avoid excessive collision between the scraper and the formed structure.

5. The SLM additive manufacturing T-shaped intersecting node printing process optimization method according to claim 4, wherein S4 It includes: S41. Adjustment of the CFST joint support height: Support the CFST joint with a block grid structure, and set a fine-tooth structure at the intersection of the grid structure and the CFST joint to facilitate the removal of the support after the structure is formed; set a support platform to reduce the support height and the direct generation of the support on the joint surface; S42. Setting of the support density: Adjust the filling line interval and the support gap; use the method of small grid block support to arrange the printing support for the upper part of the structure in the middle and late stages of printing, and use the method of regenerative grid block support to arrange the printing support for the lower part of the structure in the early stage of printing; S43. Support platform construction: Build a hollow grid support platform for the main pipe and branch pipes through parametric modeling to eliminate the internal deformation of the T-shaped intersecting node caused by the overall self-weight. Set a platform plate with a preset upward inclination angle parallel to the surface of the main pipe at the bottom of the main pipe to support the main pipe, and print a hollow grid bracket to support the platform plate with a preset upward inclination angle; the platform plate and the hollow grid bracket form a hollow grid support platform for the main pipe; the hollow grid bracket takes into account the overhang constraint and is built by a series of rods with a preset inclination angle for unsupported printing. The upper structure of the branch pipe support platform is supported by a platform plate and a hollow grid bracket with a preset upward inclination angle parallel to the branch pipe; the lower structure of the branch pipe support platform transfers the support frame above the upper surface of the main pipe to the substrate by building a bridge above the main pipe; the upper structure and the lower structure of the branch pipe support platform form a hollow grid support platform for the branch pipe.

6. A method for printing and manufacturing an SLM additive manufacturing T-shaped intersecting node, characterized in that, Including: S1. Use 3D modeling software for parametric modeling and structural model optimization to obtain the geometric model of the T-shaped intersecting node according to any one of claims 1 to 5. S2. Convert the geometric model of the T-shaped intersecting node into an STL format file, and perform inclination placement and support frame addition. S3. Perform layer slicing on the geometric model of the T-shaped intersecting node with a support frame after process optimization to obtain a planned path suitable for 3D printing. S4. Determine the printing scheme for the node model through multiple rounds of printing tests. S5. Use a laser melting printing device for 3D printing manufacturing, and obtain the T-shaped intersecting node after removing the additional support of the formed part.

7. The SLM additive manufacturing method for printing and manufacturing a T-shaped tubular joint according to claim 6, wherein The T-shaped intersecting node includes a circular pipe T-shaped intersecting node and a square pipe T-shaped intersecting node.

8. The printing process optimization system for T-shaped intersecting joints by SLM additive manufacturing, characterized in that, For implementing the method according to any one of claims 1 to 5, the T-shaped intersecting node is composed of two steel pipes of the same or different types intersecting and penetrating each other, and the system includes: A configuration module for configuring the parameters of the T-shaped intersecting node printing device: configuring the composition and printing parameters of the intersecting node printing device. A first optimization module for optimizing the structural model of the T-shaped intersecting node: optimizing the edge structure and overhang structure of the intersecting node. A second optimization module for optimizing the placement mode of the T-shaped intersecting node: optimizing the overhang angle and horizontal included angle of the intersecting node. A third optimization module for optimizing the support configuration of the T-shaped intersecting node: adjusting the support height, setting the support density, and constructing the support platform of the intersecting node to obtain a geometric model of the T-shaped intersecting node with a support frame after process optimization.

9. A computer storage medium, characterized in that, The computer storage medium stores a computer program; when the computer program runs on the computer, it causes the computer to execute the method according to any one of claims 1 to 5.

10. An electronic device, characterized in that, Including: A memory for storing the computer program. A processor for executing the computer program to implement the method according to any one of claims 1 to 5.

Images