A laser selective additive forming method for a curved grid part

Abstract

A laser selective additive manufacturing method for curved grid parts includes the following steps: S1, adjusting the printing direction to ensure that the angle between the grid surface and the substrate is greater than the self-forming angle; S2, rounding all acute angles within the grid holes; S3, rounding the corners at the connection between the overhanging bosses and the curved surface, adding a compensating ridge to the opposite side surface, and adding rib-shaped supports to the bottom of the overhanging bosses on the curved surface; S4, adding tree-shaped supports to the lower part of the irregularly shaped ribs on the curved surface; S5, applying a dot matrix to both sides of the connection between the curved surface and the substrate. This invention achieves self-forming in the laser selective additive manufacturing process of grid structures, eliminating the need for subsequent machining of the grid structure, and ensuring that the surface roughness meets specific process requirements; the curved grid structure does not crack during the laser selective additive manufacturing process, controlling surface deformation; it can improve the efficiency of laser selective additive manufacturing of curved grid structures and reduce the cost of the design and equipment.

Description

Technical Field

[0001] This invention relates to a laser selective additive manufacturing method for curved grid parts, belonging to the field of additive manufacturing design. Background Technology

[0002] The grid structure is a special type of aerodynamic control structure. Compared with traditional structures, the grid structure has a smaller chord length, a grid pressure center close to the hinge axis, and is less affected by changes in angle of attack. Therefore, the hinge torque is smaller, reducing the requirements for the actuator and allowing for lighter and smaller steering mechanisms. Simultaneously, the grid structure is easy to fold, reducing the spatial volume of the grid structure layout. Furthermore, the flow separation in the grid structure is later than in the flat plate structure, which is beneficial for maintaining lift at high angles of attack. Compared with conventional flat plate structures, the grid structure layout has greater drag. Therefore, reducing drag and improving the lift-to-drag ratio are key to the aerodynamic characteristics research of grid structures. The main measures to reduce the drag of the grid structure are to change the cross-sectional shape of the grid structure and reduce the thickness of the frame and grid bars, such as swept-back grid structure layouts, grid structure layouts with local sweep angles, and curved grid structure layouts. These grid structure layouts all have a certain drag reduction effect under supersonic conditions compared with conventional grid airfoil layouts, but the structures are more complex.

[0003] Laser selective additive manufacturing (LSM) technology offers high forming precision and fine structure, making it ideal for manufacturing curved grid parts. Patent CN20241037698 discloses an additive manufacturing method for integrally forming grid wings / rudders, employing MIG coaxial filament feeding. During grid wall additive manufacturing, the filament and grid wall maintain the same vertical tilt angle, ensuring the filament remains aligned with the grid wall. Similarly, during reinforcing rib additive manufacturing, the filament and reinforcing rib maintain a vertical alignment. Patent CN202310631510.8 discloses an automatic optimal path generation method and system for additive manufacturing of grid-like parts. By inputting the path to be printed into a computer, the system directly calculates and outputs a one-stroke path design for the grid structure. For structures that cannot be drawn in one stroke, the system adds a minimum number of auxiliary lines to the original structure to obtain a path that can be completed in one stroke, ultimately achieving a seamless additive manufacturing process. Patent CN201980047587 discloses a self-supporting grid structure, providing an additive manufacturing structure comprising a self-supporting grid structure formed by multiple unit cells. Patent CN202410751353.9 discloses an additive manufacturing method for thin-walled parts with curved surface features. The thin-walled part with curved surface features is sliced ​​into layers at equal intervals according to arc length. The resulting sliced ​​planes are divided into printing points at equal intervals according to arc length. When the print head prints each printing point, the direction of the print head is parallel to the normal vector at each printing point. By calculating the normal vector at each printing point, the angular increment of the normal vector along the v and u directions and its moving arc length are obtained. Then, the print head and positioner are controlled according to the transformation law of the normal vector. Through the pose transformation of the print head and positioner, the parallelism between the print head and the normal vector at each printing point is achieved. Patent CN202410029297.8 discloses a method, device, and medium for surface additive manufacturing path planning based on arrayed planar slices. The method involves selecting a plane normal vector in a 3D model, constructing multiple slice planes based on the plane normal vector and a preset initial offset, determining a reference offset curve in each slice plane, offsetting the reference offset curve in each slice plane with a preset slice layer thickness as the offset interval, and obtaining local additive manufacturing paths in each slice plane. Starting from the bottom of the 3D model, the local additive manufacturing paths are connected to form a global additive reciprocating path.

[0004] Among the publicly available methods, grids based on electric arc additive manufacturing often have poor surface quality and require post-machining. If the grid cell size is too small to be machined, the grid's aerodynamic characteristics will be deteriorated. Other methods mainly focus on self-forming structure design or slicing algorithms and path planning in the additive manufacturing process, without involving the design of an overall shape control scheme. Summary of the Invention

[0005] The technical problem solved by this invention is: addressing the lack of a complete grid structure color enhancement and shape control design method in the existing technology, a laser selective additive manufacturing method for curved grid parts is proposed.

[0006] The present invention solves the above-mentioned technical problem through the following technical solution:

[0007] A laser selective additive manufacturing method for curved grid parts includes:

[0008] Preset the printing direction of the curved grid structure, and set the acute angle inside the grid hole according to the additive manufacturing requirements of the curved grid;

[0009] Set the angle at the connection between the suspended boss on the curved grid and the curved part;

[0010] A compensation rib structure is provided on the other side of the curved surface at the connection between the suspended boss and the curved surface.

[0011] A rib-shaped structure is added at the connection between the bottom of the suspended boss and the curved surface for support.

[0012] A tree-shaped support structure is set at the bottom of the irregular stiffener plate in the curved part;

[0013] A dot matrix structure is set on both sides of the connection between the curved part and the component substrate;

[0014] Additive printing is performed on the completed curved grid structure.

[0015] The method for determining the printing direction of the curved grid structure is as follows:

[0016] The angle between the curved grid surface and the component substrate is determined, and the angle is not less than 55°.

[0017] The angle formed between the curved grid surface and the component substrate is greater than the self-forming angle, which is determined based on the forming material used in the curved grid structure.

[0018] The acute angles inside the grid holes are rounded, and the radius of the rounded corners is set to 0.4 times the grid feature size of the curved grid structure.

[0019] The angle at the connection between the suspended boss on the curved grid and the curved part is set as a rounded corner, and the rounded corner is set as the upper limit value of the angle according to the additive manufacturing requirements of the curved grid.

[0020] The center position of the compensation ridge structure and the position where the hanging boss on the curved surface connects to the curved surface are set to be symmetrical on both sides, and the connection position between the compensation ridge structure and the other side of the curved surface is processed with transition.

[0021] The transition between the compensation ridge structure and the other side of the curved surface is achieved by setting a transition angle and a transition fillet; the height of the transition angle between the compensation ridge structure and the connection position is the height of the compensation ridge structure, the angle of the transition angle is 45°, and the radius of the fillet between the compensation ridge structure and the connection position is determined according to the material of the compensation ridge structure.

[0022] One end of the rib structure extends into the curved surface, and the other end is connected to the bottom of the suspended boss. The length of the rib structure extending into the curved surface is equal to the thickness of the forming material used in the curved grid structure.

[0023] The rib structure sintering design adopts solid support parameters for sintering. The laser power for solid support parameter sintering is set to 220W, and the scanning speed is set to 2500mm / s.

[0024] The lattice structure is configured as a body-centered cubic or face-centered cubic structure, and the envelope size and rod diameter of the lattice structure are set according to the position of the connection between the curved part and the component substrate; the lattice structures on both sides of the connection between the curved part and the component substrate are connected in a fork-shaped combination.

[0025] The tree-shaped support structure includes a trunk and branches, with 1 and 5 branches respectively. The trunk has a top diameter of 0.5 mm and a bottom diameter of 0.8 mm. The branches have a top diameter of 0.2 mm and a bottom diameter of 0.3 mm. The branches are spaced 1.5 mm apart.

[0026] The advantages of this invention compared to the prior art are:

[0027] This invention provides a laser selective additive manufacturing method for curved grid parts, which realizes the self-forming of the grid structure during the laser selective additive manufacturing process. The grid structure does not require subsequent machining, and the surface roughness meets specific process requirements. It can ensure that the curved grid structure does not crack during the laser selective additive manufacturing process, control the surface deformation, improve the efficiency of laser selective additive manufacturing of curved grid structures, and reduce the cost of the scheme and equipment. Attached Figure Description

[0028] Figure 1 A schematic diagram of the curved grid component provided by this invention;

[0029] Figure 2 This is a schematic diagram of the fillet radius of a partial curved surface grid provided by the present invention;

[0030] Figure 3 A schematic diagram of the additive manufacturing process for a suspended boss on a curved surface provided by the present invention;

[0031] Figure 4 A schematic diagram of a rib-shaped support with a suspended boss on a curved surface provided by the present invention;

[0032] Figure 5A schematic diagram of the lower tree-shaped support of the curved irregular stiffener plate provided by the present invention;

[0033] Figure 6 A schematic diagram of the dot matrix on both sides of the connection between the curved surface and the substrate provided by the present invention. Detailed Implementation

[0034] A laser selective additive manufacturing method for curved grid parts includes the following steps: S1, adjusting the printing direction to ensure that the angle between the grid surface and the substrate is greater than the self-forming angle; S2, rounding all acute angles within the grid holes; S3, rounding the corners at the connection between the overhanging bosses and the curved surface, adding a compensating ridge to the opposite side surface, and adding rib-shaped supports to the bottom of the overhanging bosses on the curved surface; S4, adding tree-shaped supports to the lower part of the irregularly shaped ribs on the curved surface; S5, applying a dot matrix to both sides of the connection between the curved surface and the substrate. This invention achieves self-forming in the laser selective additive manufacturing process of grid structures, eliminating the need for subsequent machining of the grid structure, and ensuring that the surface roughness meets specific process requirements; the curved grid structure does not crack during the laser selective additive manufacturing process, controlling surface deformation; it can improve the efficiency of laser selective additive manufacturing of curved grid structures and reduce the cost of the design and equipment.

[0035] The laser selective additive manufacturing method for curved grid parts is as follows:

[0036] Preset the printing direction of the curved grid structure, and set the acute angle inside the grid hole according to the additive manufacturing requirements of the curved grid;

[0037] Set the angle at the connection between the suspended boss on the curved grid and the curved part;

[0038] A compensation rib structure is provided on the other side of the curved surface at the connection between the suspended boss and the curved surface.

[0039] A rib-shaped structure is added at the connection between the bottom of the suspended boss and the curved surface for support.

[0040] A tree-shaped support structure is set at the bottom of the irregular stiffener plate in the curved part;

[0041] A dot matrix structure is set on both sides of the connection between the curved part and the component substrate;

[0042] Additive printing is performed on the completed curved grid structure.

[0043] The method for determining the printing direction of curved grid structures is as follows:

[0044] The angle between the curved grid surface and the component substrate is determined, and the angle is not less than 55°. ；

[0045] The angle formed between the curved grid surface and the component substrate is greater than the self-forming angle, which is determined based on the forming material used in the curved grid structure.

[0046] The acute angles inside the grid holes are set to rounded corners, and the radius of the rounded corners is set to 0.4 times the grid feature size of the curved grid structure.

[0047] The angle at the connection between the suspended boss on the curved grid and the curved part is set to a rounded corner, and the rounded corner is set to the upper limit value of the angle according to the additive manufacturing requirements of the curved grid.

[0048] The center position of the compensation ridge structure and the position where the hanging boss on the curved surface connects to the curved surface are set to be symmetrical on both sides, and the connection position between the compensation ridge structure and the other side of the curved surface is processed with transition treatment.

[0049] The transition between the compensation ridge structure and the other side of the curved surface is achieved by setting a transition chamfer and a transition fillet. The height of the transition chamfer between the compensation ridge structure and the connection position is the height of the compensation ridge structure, the angle of the transition chamfer is 45°, and the radius of the fillet between the compensation ridge structure and the connection position is determined according to the material of the compensation ridge structure.

[0050] One end of the rib structure extends into the curved surface, and the other end is connected to the bottom of the suspended boss. The length of the rib structure extending into the curved surface is equal to the thickness of the forming material used in the curved grid structure.

[0051] The rib structure sintering design adopts solid support parameters for sintering. The laser power for solid support parameter sintering is set to 220W, and the scanning speed is set to 2500mm / s.

[0052] The lattice structure is set as a body-centered cubic or face-centered cubic structure. The envelope size and rod diameter of the lattice structure are set according to the position of the connection between the curved part and the component substrate. The lattice structures on both sides of the connection between the curved part and the component substrate are connected in a fork-shaped combination.

[0053] The tree-shaped support structure includes a trunk and 5 branches.

[0054] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details:

[0055] In the current embodiment, the laser selective additive manufacturing method for the curved grid 2 part, in a specific design and structural completion example, includes a suspended boss 11, grid 2 region 2, irregular rib plate 3, grid unit rounded corner 4, compensation ridge structure 5, rib support structure 6, tree support structure 7, and dot matrix structure 8.

[0056] The design steps are as follows:

[0057] S1, Adjust the printing direction to ensure that the angle between the surface of grid 2 and the substrate is greater than the self-forming angle;

[0058] S2, All sharp corners inside the two holes of the grid need to be rounded;

[0059] S3, the joints between the suspended boss 1 and the curved surface need to be rounded, and a compensating edge needs to be added to the opposite side surface. Rib-shaped supports should be added to the bottom of the suspended boss 1 on the curved surface. Figure 4 As shown;

[0060] S4, a tree-shaped support is added to the lower part of the curved irregular stiffener plate 3, such as Figure 5 As shown;

[0061] S5, dot matrix is ​​applied to both sides of the connection between the curved surface and the substrate, such as Figure 6 As shown.

[0062] The self-forming angle in S1 varies depending on the forming material, such as... Figure 1 The curved grid 2 shown is made of stainless steel, and the angle between the surface of the grid 2 and the substrate is ≥55°.

[0063] All acute angles within the two holes of the grid in S2 need to be rounded, such as... Figure 2 As shown, the radius is 0.4 × grid 2 feature size, grid 2 feature size is 3mm, and the corner radius is R1.2.

[0064] The fillet at the connection between the suspended boss 1 on the curved surface and the curved surface in S3 is set to the upper limit while meeting the installation area requirements, with a fillet radius of R3.

[0065] The center position of the compensation edge 5 in S3 corresponds to the connection point between the overhanging boss 1 and the curved surface, such as... Figure 3 As shown, the width is 1mm and the height is 0.6mm, and the compensation edge 5 transitions with the curved surface.

[0066] The rib support 6 added to the bottom of the suspended boss 1 on the curved surface in S3 has a thickness of 0.4mm, a spacing of 1mm, a notch of 0.3mm, an angle of 55°, a tooth height of 0.6mm, a tooth pitch of 0.5mm, and penetrates into the part body to a depth equal to one layer thickness of the laser-selected additive material.

[0067] The rib-shaped support 6 added to the bottom of the suspended boss 1 on the curved surface in S3 is sintered using the solid support parameters.

[0068] The tree-shaped support 7 added to the lower part of the curved irregular stiffener 3 in S4 has a trunk top diameter of 0.5mm, a trunk bottom diameter of 0.8mm, a branch top diameter of 0.2mm, a branch bottom diameter of 0.3mm, and 5 branches on the trunk with a spacing of 1.5mm.

[0069] The tree-shaped support 7 added to the lower part of the curved irregular stiffener plate 3 in S4 is sintered using the solid support parameters.

[0070] The dot matrix applied to both sides of the connection between the curved surface and the substrate in S5, the dot matrix unit type 8 includes but is not limited to body-centered cubic and face-centered cubic.

[0071] The dot matrix applied to both sides of the connection between the curved surface and the substrate in S5 has an envelope size of 5mm and a rod diameter of 0.5mm for the 8 dot matrix units.

[0072] The dot matrix 8 applied to both sides of the connection between the curved surface and the substrate in S5 is a regular hexagon with a rod diameter.

[0073] The dot matrix 8 applied to both sides of the connection between the curved surface and the substrate in S5 is in the form of a coarse fork.

[0074] The dot matrix 8 applied to both sides of the connection between the curved surface and the substrate in S5 is sintered using solid support parameters.

[0075] Solid part parameters were sintered using a laser with a power of 250W and a scanning speed of 900mm / s.

[0076] Solid support parameters were sintered with a laser power of 220W and a scanning speed of 2500mm / s.

[0077] The compensation edge 5 transitions to the curved surface by a combination of a chamfer and a fillet. The height of the chamfer between the compensation edge 5 and the curved surface is equal to the height of the compensation edge 5. The chamfer angle between the compensation edge 5 and the curved surface is 45°. The radius of the fillet between the chamfer and the curved surface is R0.6.

[0078] The parameters of solid parts are sintered, depending on the material.

[0079] Titanium alloy, laser power 250W-350W, scanning speed 1000mm / s-1750mm / s;

[0080] High-temperature alloy, laser power 200W-300W, scanning speed 800mm / s-1200mm / s;

[0081] Aluminum alloy, laser power 300W-380W, scanning speed 900mm / s-1600mm / s;

[0082] Stainless steel, laser power 220W-300W, scanning speed 800mm / s-1000mm / s.

[0083] Solid support parameters are sintered, depending on the material.

[0084] Titanium alloy, laser power 150W-250W, scanning speed 2000mm / s-2750mm / s;

[0085] High-temperature alloy, laser power 200W-300W, scanning speed 2000mm / s-2750mm / s;

[0086] Aluminum alloy, laser power 300W-380W, scanning speed 900mm / s-1600mm / s;

[0087] Stainless steel, laser power 220W-300W, scanning speed 1800mm / s-2500mm / s.

[0088] The compensation edge 5 transitions to the curved surface by a combination of a chamfer and a fillet. The height of the chamfer between the compensation edge 5 and the curved surface is equal to the height of the compensation edge. The chamfer angle between the compensation edge and the curved surface is ≤45°. The radius of the fillet between the chamfer and the curved surface is ≥(0.5×compensation edge height).

[0089] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0090] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A laser selective additive manufacturing method for curved grid parts, characterized in that... include: The printing direction of the curved grid structure is preset, and the acute angle inside the grid hole is set according to the additive manufacturing requirements of the curved grid. The method for determining the printing direction of the curved grid structure is as follows: it is determined according to the angle formed between the surface of the curved grid and the substrate of the part, and the angle is not less than 55°. The angle formed between the surface of the curved grid and the substrate of the part is greater than the self-forming angle, which is determined according to the forming material used in the curved grid structure. The acute angle inside the grid hole is set as a rounded corner, and the radius of the rounded corner is set to 0.4 times the grid feature size of the curved grid structure. Set the angle at the connection between the suspended boss on the curved grid and the curved part; the angle at the connection between the suspended boss on the curved grid and the curved part is set to a rounded corner; A compensating ridge structure is provided on the other side of the curved surface at the connection between the suspended boss and the curved surface. The center position of the compensating ridge structure is symmetrical to the position at the connection between the suspended boss and the curved surface. A transition treatment is applied to the connection position between the compensating ridge structure and the other side of the curved surface. The transition treatment between the compensating ridge structure and the other side of the curved surface is achieved by setting a transition angle and a transition fillet. The height of the transition angle between the compensating ridge structure and the connection position is the height of the compensating ridge structure, the angle of the transition angle is 45°, and the fillet radius between the compensating ridge structure and the connection position is determined according to the material of the compensating ridge structure. A rib-shaped structure is added at the connection between the bottom of the suspended boss and the curved surface for support; one end of the rib-shaped structure extends into the curved surface and the other end connects to the bottom of the suspended boss. The length of the rib-shaped structure extending into the curved surface is equal to the thickness of the forming material used in the curved grid structure. The rib-shaped structure is designed for sintering, and the sintering parameters adopt solid support parameters. The laser power for solid support parameter sintering is set to 220W, and the scanning speed is set to 2500mm / s. A tree-shaped support structure is provided at the lower part of the irregular stiffener plate of the curved part; the tree-shaped support structure includes a trunk and branches, with 1 and 5 branches respectively, the top diameter of the trunk is 0.5mm, the bottom diameter of the trunk is 0.8mm, the top diameter of the branches is 0.2mm, the bottom diameter of the branches is 0.3mm, and the interval between the branches is 1.5mm. A lattice structure is provided on both sides of the connection between the curved part and the component substrate; the lattice structure is configured as a body-centered cubic or face-centered cubic structure, and the envelope size and rod diameter of the lattice structure are set according to the connection position between the curved part and the component substrate; the lattice structures on both sides of the connection between the curved part and the component substrate are connected in a fork-shaped combination. Additive printing is performed on the completed curved grid structure.

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