A thin-wall cantilever skeleton structure and laser selective melting forming method
By establishing a three-dimensional model in a thin-walled cantilever skeleton structure and adding a support structure, the high-precision laser selection melting forming process is used to solve the problems of deformation and cracking during the melting forming of the laser selection, and an efficient and accurate forming effect is achieved.
Patent Information
- Application Number
- CN202210184070.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-02-24
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2042-02-24
AI Technical Summary
Thin-walled cantilever skeleton structures are prone to deformation and cracking during the melting and forming of laser selection areas, resulting in poor dimensional accuracy.
By establishing a three-dimensional model of the skeleton structure, selecting the appropriate forming direction and adding grid support and anti-deformation support, a jump raster scanning strategy and high-precision laser selection melt forming process parameters are adopted, combined with heat treatment to reduce thermal stress and deformation.
It realizes high efficiency and high-quality forming of thin-walled cantilever skeleton structures, shortens the processing cycle, and improves material utilization and dimensional accuracy.
Smart Images
Figure CN114619048B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of additive manufacturing, and relates to a thin-wall cantilever skeleton structure and a laser selective melting forming method. Background Art
[0002] Skeleton structures are mainly used to cover thermal engine components, which are generally thin-walled parts with a thickness range of 0.5-2mm. Traditional processing requires the use of bar machining, which has problems such as extremely low material utilization, long processing cycle, and large deformation. Laser selective melting forming technology can be based on the three-dimensional CAD model of the part. By stacking the material layer by layer, the product prototype or component is formed. It is not restricted by the structure of the part, and has a short manufacturing cycle and high material utilization. It is very suitable for the production of thin-walled cantilever skeleton structures.
[0003] Since laser selective melting uses a high-energy laser beam as the energy source, the high cooling rate during the forming process will cause greater thermal stress, resulting in deformation and even cracking of the skeleton structure. Summary of the invention
[0004] The technical problem solved by the present invention is: a thin-walled cantilever skeleton structure and a laser selective melting forming method, which can achieve high-efficiency and high-quality forming of thin-walled cantilever structures, and solve the problems of easy deformation and cracking and poor dimensional accuracy during the forming of thin-walled cantilever structures.
[0005] The technical solutions provided by the present invention are as follows:
[0006] First,
[0007] A thin-wall cantilever skeleton structure, comprising: a main body, a cantilever and a hanging connecting section;
[0008] The main body is a frame structure composed of horizontal beams and vertical beams, and a plurality of hollow areas are arranged in the frame structure;
[0009] The cantilever is provided with a plurality of hanging connection sections, and the cantilever and the main body are connected through the hanging connection sections; the cantilever is arranged along the vertical direction.
[0010] Preferably, the main body and the cantilever are both made of titanium alloy.
[0011] Preferably, the shape of the hollow area is rectangular.
[0012] Preferably, the angle between the overhanging connecting section and the horizontal plane is less than 30°.
[0013] Preferably, the wall thickness of the main body and the cantilever is in the range of 0.5-2 mm.
[0014] Second,
[0015] A method for performing laser selective melting forming on a thin-wall cantilever skeleton structure as described in the first aspect comprises the following steps:
[0016] 1) Establish a three-dimensional model of a thin-walled cantilever skeleton structure;
[0017] 2) According to the structural characteristics of the thin-walled cantilever skeleton structure, the direction in which the cantilever and the horizontal plane of the substrate are at an angle of more than 45° is selected as the forming direction;
[0018] 3) Modify the lower end surface of the beam so that the angle between the lower end surface of the beam and the horizontal plane is greater than or equal to 45°. Further, a pointed top hollow structure can be used to achieve self-supporting forming of the overhanging area. Obtain an optimized three-dimensional model of the thin-wall cantilever skeleton structure;
[0019] 4) adding a grid support downwardly on the lower end surface of the overhanging connecting section, and setting an anti-deformation support in the horizontal direction in the frame structure to obtain a three-dimensional model with the grid support and the anti-deformation support added;
[0020] 5) Slice the three-dimensional model with grid support and anti-deformation support, set the laser selective melting forming process parameters, select high-precision small laser power, large scanning spacing, high scanning speed process parameters and jump raster scanning strategy, and obtain the processing program file;
[0021] 6) Importing the processing program file into the equipment, performing laser selective melting forming on a titanium alloy substrate in an inert atmosphere, and obtaining a thin-walled cantilever skeleton structure with a substrate, a grid support, and an anti-deformation support;
[0022] 7) heat treating the thin-walled cantilever skeleton structure with the substrate, grid support and anti-deformation support;
[0023] 8) Separating the substrate and the thin-walled cantilever skeleton structure, removing the grid support and anti-deformation support added in step 4), and obtaining a thin-walled cantilever skeleton structure.
[0024] Preferably, the step 4) also includes: using simulation software to simulate the deformation after laser selective melting, heat treatment and wire cutting in advance, and adding anti-deformation support to the area on the main body where the dimensional deformation exceeds the precision requirement of GB6414-CT6 to prevent the deformation of the skeleton structure, and the thickness of the anti-deformation support is 2mm.
[0025] Preferably, in step 4), the grid support includes a plurality of grid arrays, the size of each grid in the grid array is not greater than 0.6 mm×0.6 mm, the side length of the grid array ranges from not less than 4 mm×4 mm; and the gap width between two adjacent grid arrays is not greater than 0.8 mm.
[0026] Preferably, the grid support and the lower end surface of the overhanging connection section are connected via teeth, and the height of the teeth is not greater than 1 mm.
[0027] Preferably, in step 5), the laser selective melting forming process parameters of the anti-deformation support, the main body, the cantilever and the overhanging connecting section are as follows:
[0028] Laser power: 180~220W, scanning speed: 1100~1300mm / s, scanning spacing: 0.08~0.12mm, spot diameter: 90~110μm, powder layer thickness: 0.03~0.06mm.
[0029] Preferably, in step 5), the laser selective melting forming process parameters of the grid support are as follows:
[0030] Laser power: 360-380W, scanning speed: 2500-2900mm / s, scanning spacing: 0.08-0.12mm, spot diameter: 120-140μm, scan once for every two layers of powder.
[0031] Preferably, the powder spreading speed does not exceed 50 mm / s; a rubber scraper is used in the powder spreading process of laser selective melting.
[0032] Preferably, in step 7), the heat treatment temperature ranges from 750 to 850° C., the holding time ranges from 3 to 5 hours, and the cooling gas during the heat treatment is argon.
[0033] Preferably, in step 8), electric spark wire cutting is used to separate the substrate and the thin-wall cantilever skeleton structure, and the anti-deformation support is removed.
[0034] Preferably, in step 8), the grid support is removed by grinding.
[0035] The advantages of the present invention compared with the prior art are:
[0036] 1) The present invention can be formed by establishing a three-dimensional model of the skeleton structure, with high design freedom. Compared with the traditional bar material machining + wire cutting process, the processing cycle is short, the material utilization rate is high, the deformation is small, and the dimensional accuracy is high.
[0037] 2) The present invention adopts a jumping raster scanning strategy to increase the cooling time of the sintered area, reduce heat accumulation, reduce stress, and control deformation.
[0038] 3) The present invention achieves support-free and high-precision forming of the main structure by modifying the design of the main structure of the skeleton and adding anti-deformation supports to control the deformation of the main structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Figure 1It is a schematic diagram of the thin-wall cantilever skeleton structure and forming direction of the present invention;
[0040] Figure 2 (a) (b) is a schematic diagram of a three-dimensional model of the thin-walled cantilever skeleton structure after adaptive modification of the present invention;
[0041] Figure 3 This is a schematic diagram of the anti-deformation support of the present invention;
[0042] Figure 4 It is a structural schematic diagram of the grid support of the present invention;
[0043] Figure 5 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION
[0044] In the present invention, the skeleton structure is adaptively modified and the laser selective melting forming process is adjusted to reduce the forming stress and improve the dimensional accuracy of the thin-wall cantilever skeleton structure.
[0045] The present invention is described with reference to the accompanying drawings.
[0046] like Figure 1 As shown, the present invention is a thin-walled cantilever skeleton structure, comprising: a main body 1, a cantilever 2 and a suspension connection section 3. The main body 1 is a frame structure composed of a horizontal beam and a vertical beam, and a plurality of hollow areas are arranged in the frame structure; a plurality of suspension connection sections 3 are arranged on the cantilever 2, and the cantilever 2 and the main body 1 are connected by the suspension connection section 3. The main body 1 and the cantilever 2 are both made of titanium alloy. The shape of the hollow area is rectangular. The angle between the suspension connection section 3 and the horizontal plane is less than 30°.
[0047] The present invention provides a laser selective melting forming and deformation control method, such as Figure 5 As shown, the following steps are included:
[0048] (1) Use modeling software such as UG or Pro / E to create a three-dimensional model of a thin-walled cantilever skeleton structure with a wall thickness of 1.5 mm and a cantilever length of 58 mm. Figure 1 shown.
[0049] (2) According to the structural characteristics of the parts, select Figure 1 The cantilever 2 shown is 90° to the horizontal plane of the substrate as the forming direction to ensure the unsupported forming of the cantilever 2. The cantilever 2 structure does not require any additional support.
[0050] (3) Adaptively modify the thin-walled cantilever skeleton structure, change the overhanging area in the main body 1 into a pointed hollow structure, such as the structure in Figure 2(a) or Figure 2(b), make a smooth transition on the top of the triangle, obtain the final three-dimensional model of the thin-walled cantilever skeleton structure, and then export the model to STL format with an export accuracy of not less than 0.008 mm. Among them, the angle between the overhanging area and the horizontal plane is less than 30°, and it cannot be self-supported during the processing process.
[0051] (4) Using simulation software, the deformation of the three-dimensional model in Figure 2 after laser selective melting, heat treatment, and wire cutting is simulated. For areas where the dimensional deformation exceeds the accuracy requirements of GB6414-CT6, add Figure 3 The anti-deformation support shown is used to prevent the skeleton structure from deforming. The grid support style is as follows Figure 4 As shown. The grid size is 0.6mm×0.6mm, the rotation angle is 45°, the cutting is 5mm×5mm, the gap width is 0.6mm, the upper tooth height is 0.8mm, the tooth top width is 0.2mm, the tooth root width is 0.6mm, and the tooth spacing is 0.1mm.
[0052] (5) The skeleton structure often uses lighter titanium alloy materials. The parameters of laser selective melting are: laser power 180-220 W, scanning speed 1100-1300 mm / s, scanning spacing 0.08-0.12 mm, spot diameter 90-110 μm, powder layer thickness 0.03-0.06 mm, phase angle 67°; the anti-deformation support processing parameters are the same as the part processing parameters.
[0053] Mesh support processing parameters: laser power 360~380W, scanning speed 2500~2900mm / s, spot diameter 120~140μm, scanning interval 0.08~0.12mm, scan once every 1 layer.
[0054] The scanning strategy adopts: jumping raster scanning strategy, which can increase the cooling time of the sintered area and reduce thermal stress. The rubber scraper is used in the powder spreading process of laser selective melting to reduce the deformation resistance between the powder spreading mechanism and the part, avoiding damage to the part structure. The low-speed powder spreading mode can reduce the tangential effect of the powder spreading mechanism on the part, reducing part deformation and vibration.
[0055] (6) The thin-walled cantilever skeleton structure with the substrate is heat treated at 800°C, kept at this temperature for 4 hours, and cooled by filling with argon gas.
[0056] (7) Electric spark wire cutting is used to separate the substrate and the thin-walled cantilever skeleton structural components and remove the anti-deformation support. The pulse waveform is a rectangular pulse, the pulse width is set to 20-45 μs, the pulse interval is 150-200 μs, and the current is 5-7 A; then, manual grinding is used to remove the grid support, and the wire cutting surface is grinded to ensure a smooth surface to obtain a thin-walled cantilever skeleton structure.
[0057] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.
[0058] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.
Claims
1. A method for laser selective melting of a thin-walled cantilever skeleton structure, characterized in that: A thin-wall cantilever skeleton structure, comprising: a main body (1), a cantilever (2) and a hanging connecting section (3); The main body (1) is a frame structure composed of horizontal beams and vertical beams, and a plurality of hollow areas are arranged in the frame structure; The cantilever (2) is provided with a plurality of overhanging connection sections (3), and the cantilever (2) and the main body (1) are connected via the overhanging connection sections (3); The main body (1) and the cantilever (2) are both made of titanium alloy; The shape of the hollow area is rectangular; The steps include: 1) Establish a three-dimensional model of a thin-walled cantilever skeleton structure; 2) selecting a direction in which the cantilever (2) forms an angle of more than 45° with the horizontal plane as the forming direction; 3) Modify the lower end surface of the beam so that the angle between the lower end surface of the beam and the horizontal plane is greater than or equal to 45°; 4) adding a grid support downwardly on the lower end surface of the hanging connection section (3), and setting an anti-deformation support in the horizontal direction in the frame structure to obtain a three-dimensional model with the grid support and the anti-deformation support added; 5) Slice the three-dimensional model with grid support and anti-deformation support, set laser selective melting forming process parameters, and obtain a processing program file; 6) Importing the processing program file into the equipment, performing laser selective melting forming on the substrate in an inert atmosphere, and obtaining a thin-walled cantilever skeleton structure with a substrate, a grid support and an anti-deformation support; 7) heat treating the thin-walled cantilever skeleton structure with the substrate, grid support and anti-deformation support; 8) separating the substrate and the thin-walled cantilever skeleton structure, removing the grid support and anti-deformation support added in step 4), and obtaining a thin-walled cantilever skeleton structure; The step 4) further comprises: using simulation software to simulate the deformation after laser selective melting, heat treatment and wire cutting in advance, and adding anti-deformation support to the area on the main body (1) where the dimensional deformation exceeds the accuracy requirement of GB6414-CT6; In the step 4), the grid support includes a plurality of grid arrays, the size of each grid in the grid array is not greater than 0.6 mm×0.6 mm, the side length of the grid array has a value range of not less than 4 mm×4 mm; and the gap width between two adjacent grid arrays is not greater than 0.8 mm.
2. The method for selective laser melting according to claim 1, characterized in that: The grid support and the lower end surface of the overhanging connection section (3) are connected via teeth, and the height of the teeth is no more than 1 mm.
3. The method for selective laser melting according to claim 2, characterized in that: In the step 5), the laser selective melting forming process parameters of the anti-deformation support, the main body (1), the cantilever (2) and the overhanging connecting section (3) are specifically as follows: Laser power: 180~220W, scanning speed: 1100~1300mm / s, scanning spacing: 0.08~0.12mm, spot diameter: 90~110μm, powder layer thickness: 0.03~0.06mm.
4. The method for selective laser melting according to claim 3, characterized in that: In step 5), the laser selective melting forming process parameters of the grid support are as follows: Laser power: 360-380W, scanning speed: 2500-2900mm / s, scanning spacing: 0.08-0.12mm, spot diameter: 120-140μm, scan once for every two layers of powder.
5. The method for performing selective laser melting according to claim 4, characterized in that: The powder spreading speed does not exceed 50 mm / s; a rubber scraper is used in the powder spreading process of laser selective melting.
6. The method for selective laser melting according to claim 5, characterized in that: In the step 7), the heat treatment temperature ranges from 750 to 850° C., the holding time ranges from 3 to 5 hours, and the cooling gas during the heat treatment is argon.
7. The method for selective laser melting according to claim 6, characterized in that: In the step 8), the substrate and the thin-wall cantilever skeleton structure are separated by electric spark wire cutting, and the anti-deformation support is removed.
8. The method for selective laser melting according to claim 7, characterized in that: In the step 8), the grid support is removed by grinding.
9. The method for selective laser melting according to claim 1, characterized in that: The angle between the suspended connecting section (3) and the horizontal plane is less than 30°.
10. The method for selective laser melting according to claim 9, characterized in that: The wall thickness of the main body (1) and the cantilever (2) ranges from 0.5 to 2 mm.