A stable forming method for large-size thin-walled ring-shaped parts by selective laser melting

Abstract

The present application belongs to the field of metal part additive manufacturing, and relates to a stable forming method for laser selective melting of large-size thin-wall annular parts. The model feature structure is designed as follows: the part outer diameter is greater than or equal to 600 mm, the wall thickness is less than or equal to 1.5 mm, and cross-shaped inclined growth semicircular arc reinforcing rib structures are uniformly added to the inner and outer walls for stable forming; the semicircular arc-shaped reinforcing ribs are 45-60 degrees to the horizontal direction along the inner and outer walls; after the three-dimensional model design is completed and slice processing is performed, laser selective melting forming process parameters are set, powder is added, and printing is performed on the substrate; after the printing is completed, the part is annealed; and the final part is obtained through wire cutting and support removal. The cross-shaped inclined growth semicircular arc reinforcing rib structures added to the inner and outer walls of the thin-wall annular parts can not only realize self-supporting forming during laser selective melting, but also effectively improve the structural stability and forming process stability.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing of metal parts and relates to a method for stable forming of large-size thin-walled annular parts by selective laser melting. Background Technology

[0002] Advanced aerospace equipment is constantly evolving towards higher thrust-to-weight ratios, higher reliability, longer lifespans, and greater economic affordability. These stringent multi-indicator requirements necessitate complex, lightweight, and highly efficient structures for key components of aero-engines, with an increasing trend towards integral structural components. Consequently, the size and complexity of individual parts are constantly increasing, placing increasingly stringent demands on the processing and manufacturing of structural components. Traditional forming processes such as forging, casting, welding, and machining face challenges such as long production cycles, low yield rates, and high manufacturing costs. In particular, the increasing number of irregularly shaped structures makes traditional methods inadequate for their manufacturing.

[0003] Selective laser melting (SLM) is an advanced laser additive manufacturing technology developed based on prototyping techniques. Using a high-energy laser beam to melt metal powder layer by layer based on a three-dimensional digital model of the part, a three-dimensional solid part is manufactured through a process of layer-by-layer powder deposition, melting, and solidification. This technology enables rapid, moldless forming of metal parts with exceptionally complex structures, and is particularly suitable for manufacturing intricate and complex aerospace components.

[0004] However, during the selective laser melting process of large-sized parts, the accumulation of residual thermal stress during forming significantly increases the risk of cracking and deformation. This is especially true for large, thin-walled annular parts with an outer diameter of over 600mm and a wall thickness of less than 1.5mm, where the thin wall results in poor rigidity and susceptibility to deformation during manufacturing. Therefore, improving structural stability and process stability are critical issues that urgently need to be addressed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the stable forming of large-sized thin-walled annular parts, addressing the urgent need for laser selective melting in the development of aerospace large-size thin-walled annular parts.

[0006] To solve this technical problem, the technical solution of the present invention is as follows:

[0007] A method for stabilizing the forming of large-sized thin-walled annular parts by selective laser melting, comprising the following steps:

[0008] Step 1, Structural Optimization Design: The structural optimization design features are as follows: the outer diameter of the part is ≥600mm, the wall thickness is ≤1.5mm, and a cross-shaped inclined semi-circular arc reinforcing rib structure that assists in the stable forming of thin walls is uniformly added to the inner and outer walls.

[0009] The semi-circular reinforcing ribs are at an angle of 45° to 60° with the horizontal direction along the inner and outer walls. In the laser selective melting process of the present invention, in order to ensure self-supporting forming without causing the reinforcing ribs to be too dense, after multiple forming tests and simulation analysis, the angle is set to 45° to 60° in this process.

[0010] Step 2, Data Processing: Set the part placement direction, slice the model designed in Step 1, and complete the parameter settings for the slice data to obtain a printable file; the slice layer thickness is set to 0.06mm;

[0011] Step 3: Set appropriate laser selective melting forming process parameters and import the file into the laser selective melting forming equipment;

[0012] Step 4: After preheating the equipment substrate to the specified temperature, level the equipment substrate, add powder, and print on the substrate. The entire printing process is carried out under inert gas protection.

[0013] Step 5: After printing, anneal the parts together with the substrate. Annealing process: heat to 600℃~1200℃ and hold for 1h~4h.

[0014] Step 6: After heat treatment, separate the part from the substrate, remove the surface support structure of the part, and clean, grind, polish and sandblast the part to obtain the final part.

[0015] The component placement direction is set so that the component height direction is perpendicular to the substrate.

[0016] Preferably, the height of the part is 50mm to 700mm.

[0017] Preferably, the distance between the reinforcing ribs is 10-30 mm.

[0018] Preferably, the powder is titanium alloy powder with a particle size range of 15-53 μm, a sphericity of ≥90%, and a flowability of ≤36s / 50g; the laser selective melting forming parameters in step three are: powder layer thickness of 0.04-0.06 mm, laser power of 320-380 W, scanning rate of 1100-1600 mm / s, and oxygen content in the forming chamber controlled below 200 ppm.

[0019] Preferably, the powder is a high-temperature alloy powder with a particle size range of 15-53 μm, a sphericity of ≥92%, and a flowability of ≤28s / 50g; the laser selective melting forming parameters in step three are: powder layer thickness of 0.04-0.06 mm, laser power of 450-600 W, scanning rate of 1300-1800 mm / s, and oxygen content in the forming chamber controlled below 200 ppm.

[0020] The beneficial effects of this invention are:

[0021] (1) This invention proposes a structure / process integrated design method for shape control. Through the unique semi-circular arc cross-shaped inclined growth reinforcing rib structure design, it solves the problem of precise shape control of laser selective melting of large-size thin-walled integral complex components. It can realize the one-time stable forming of components with outer diameter ≥600mm, height 50mm~700mm, and wall thickness ≤1.5mm, with stable dimensions and no cracking.

[0022] (2) The laser selective melting forming method of the present invention is specifically developed for large-size thin-walled annular parts in aerospace. A cross-shaped reinforcing rib structure is uniformly added to the inner and outer walls of the large-size thin-walled annular parts. The semi-circular reinforcing ribs grow at an angle of 45° to 60° along the inner and outer walls, which not only achieves self-supporting forming, but also effectively improves the structural stability and forming process stability. Attached Figure Description

[0023] To more clearly illustrate the technical solutions implemented in this invention, the accompanying drawings used in the embodiments of this invention will be briefly explained below. Obviously, the drawings described below are merely some embodiments of this invention. Those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0024] Figure 1 This is a partial structural diagram of the part of the present invention, wherein X is a cross-shaped inclined semi-circular reinforcing rib structure;

[0025] Figure 2 for Figure 1 A magnified view of X. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The features of various aspects of the embodiments of the present invention will now be described in detail. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can also be practiced without these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by illustrating examples. The invention is not limited to any specific setups and methods provided below, but covers all improvements, substitutions, etc., to product structures and methods without departing from the spirit of the invention.

[0028] In the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the invention.

[0029] Example 1:

[0030] The part has a diameter of 1000mm, a wall thickness of 0.8mm, and a height of 300mm. It is made of nickel-based high-temperature alloy.

[0031] First, structural optimization design is carried out: a cross-shaped inclined semi-circular arc reinforcing rib structure with a thickness of 0.8mm is added evenly to the inner and outer walls to help stabilize the shape. The reinforcing ribs are at a 45° angle to the horizontal direction along the inner and outer walls, and the distance between the reinforcing ribs is 20mm.

[0032] Then, data processing is performed: the part placement direction is set to be perpendicular to the substrate in the height direction of the part, and the design model is sliced ​​using slicing software to obtain the file to be printed. The slice layer thickness is selected as 0.06mm.

[0033] Then, printing and post-processing are performed. Appropriate laser selective melting forming process parameters are set, and the file is imported into the laser selective melting forming equipment. After preheating the equipment substrate to 200°C, the equipment substrate is leveled, and high-temperature alloy powder is added with a particle size range of 15-53μm, a sphericity of 92%, and a flowability of 26s / 50g.

[0034] Printing is performed on the substrate with the following parameters: laser power 550W, scanning rate 1500mm / s, and oxygen content in the forming chamber controlled below 200ppm. After printing, the part and the substrate are subjected to annealing heat treatment at 1100℃ for 1 hour. After heat treatment, the part is separated from the substrate, the surface support structure of the part is removed, and the part is cleaned, polished, and sandblasted to obtain the final part.

[0035] The formed parts are of good quality, with stable dimensions and no cracks, and the inner and outer diameter dimensional accuracy reaches ±0.55mm.

[0036] Example 2:

[0037] The part has a diameter of 1230mm, a wall thickness of 1.5mm, a height of 600mm, and is made of titanium alloy.

[0038] First, structural optimization design is carried out: a cross-shaped inclined semi-circular arc reinforcing rib structure with a thickness of 1.5mm is added evenly to the inner and outer walls to help stabilize the shape. The reinforcing ribs are at a 45° angle to the horizontal direction along the inner and outer walls, and the distance between the reinforcing ribs is 30mm.

[0039] Then, data processing is performed: the part placement direction is set to be perpendicular to the substrate in the height direction of the part, and a special slicing software is used to slice the designed model to obtain the file to be printed. The slice layer thickness is selected as 0.05mm.

[0040] Then, printing and post-processing are performed. Appropriate laser selective melting forming process parameters are set, and the file is imported into the laser selective melting forming equipment. After preheating the equipment substrate to 200°C, the equipment substrate is leveled, and titanium alloy powder is added with a particle size range of 15-53μm, a sphericity of 91%, and a flowability of 35s / 50g.

[0041] Printing is performed on the substrate with the following parameters: laser power 350W, scanning rate 1300mm / s, and oxygen content in the forming chamber controlled below 200ppm. After printing, the parts and substrate are annealed together for heat treatment at 800℃ for 2 hours. After heat treatment, the parts are separated from the substrate, the surface support structure of the parts is removed, and the parts are cleaned, polished, and sandblasted to obtain the final parts.

[0042] The formed parts are of good quality, with stable dimensions and no cracks, and the inner and outer diameter dimensional accuracy reaches ±0.46mm.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A method for stable forming of large-size thin-walled annular parts by laser selective melting, characterized in that: The large-sized thin-walled annular component has an outer diameter ≥ 600 mm and a wall thickness ≤ 1.5 mm; the method includes the following steps: Step 1: Structural optimization design: Add cross-shaped inclined semi-circular arc reinforcing ribs uniformly to the inner and outer walls to assist in the stable forming of thin walls; the distance between the reinforcing ribs is 10~30mm; The semi-circular reinforcing ribs form an angle of 45° to 60° with the horizontal direction along the inner and outer walls; Step 2, Data Processing: Set the orientation of the parts, slice the model designed in Step 1, and then set the parameters of the slice data to obtain a printable file. Step 3: Set appropriate laser selective melting forming process parameters and import the file into the laser selective melting forming equipment; Step 4: After preheating the equipment substrate to the specified temperature, level the equipment substrate, add powder, and print on the substrate. The entire printing process is carried out under inert gas protection. Step 5: After printing, the parts and the substrate are subjected to annealing heat treatment. Heat treatment regime: heat up to 600℃~1200℃ and hold for 1h~4h. Step 6: After heat treatment, separate the part from the substrate, remove the surface support structure of the part, and clean, grind, polish and sandblast the part to obtain the final part; the height of the part is 50mm~700mm.

2. The method for stable forming of large-size thin-walled annular parts by laser selective melting according to claim 1, characterized in that: The component placement direction is set so that the component height direction is perpendicular to the substrate.

3. The method for stable forming of large-size thin-walled annular parts by laser selective melting according to claim 1, characterized in that: The powder is titanium alloy powder with a particle size range of 15~53μm, a sphericity of ≥90%, and a flowability of ≤36s / 50g.

4. The method for stable forming of large-size thin-walled annular parts by laser selective melting according to claim 3, characterized in that: The parameters for laser selective melting and forming in step three are as follows: powder layer thickness 0.04~0.06mm, laser power 320~380W, scanning rate 1100~1600mm / s, and oxygen content in the forming chamber controlled below 200ppm.

5. The method for stable forming of large-size thin-walled annular parts by laser selective melting according to claim 1, characterized in that: The powder is a high-temperature alloy powder with a particle size range of 15~53μm, a sphericity of ≥92%, and a flowability of ≤28s / 50g.

6. The method for stable forming of large-size thin-walled annular parts by laser selective melting according to claim 5, characterized in that: The parameters for laser selective melting and forming in step three are as follows: powder layer thickness 0.04~0.06mm, laser power 450~600W, scanning rate 1300~1800mm / s, and oxygen content in the forming chamber controlled below 200ppm.

7. The method for stable forming of large-size thin-walled annular parts by laser selective melting according to claim 1, characterized in that: In step two, the slice thickness is set to 0.06 mm.

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