A lightweight method for titanium alloy lattice impeller formed by selective laser melting

Abstract

The present invention provides a lightweight method for a titanium alloy lattice impeller formed by laser selective melting, which belongs to the field of additive manufacturing titanium alloy forming technology, comprising: first, performing parameterized modeling based on the Gyroid function, a classic implicit function of TPMS, to obtain a lattice model; then, designing a solid impeller model and performing numerical simulation to determine the stress and deformation distribution of the impeller under rotating working conditions, and based on the results obtained in the numerical simulation of the impeller, performing internal cavity design on the solid impeller model to determine the filling area and wall thickness; then, filling the lattice model into the solid impeller model, setting the SLM process parameters for laser melting forming, obtaining the laser selective melting simulation results, and designing the powder discharge holes based on the obtained results to obtain a lattice structure compressor impeller. The design of the lattice structure provided by the present invention can reduce deformation during the impeller forming process, so that the impeller achieves a 20% weight reduction effect, achieving the effect of reducing costs and increasing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing titanium alloy forming, and in particular to a lightweight method for forming a titanium alloy lattice impeller by selective laser melting. Background Art

[0002] The compressor impeller has a complex structure and shape, including various curves and surfaces, and is difficult to process overall.

[0003] At present, traditional CNC machining equipment is expensive and cannot quickly adapt to temporary changes in machining requirements. When the impeller design or requirements change, the machine tools need to be reprogrammed and adjusted; casting usually requires a lot of subsequent processing (such as cutting, grinding, etc.) to meet the final design requirements, which increases production costs and time; forging requires special molds and tooling equipment, the mold cost is high and the manufacturing cycle is long; welding usually may have defects such as cracks and slag inclusions at the weld joints, affecting the performance and service life of the impeller. Thermal stress and deformation will be generated during the welding process, affecting the shape and dimensional accuracy of the impeller. The welded impeller usually needs to undergo subsequent processing such as grinding and trimming to meet the final design requirements.

[0004] Traditional impeller manufacturing methods are complex and require long production cycles. Furthermore, traditional manufacturing methods have already reached their limits in reducing impeller weight. Furthermore, topology optimization, a method developed with the recent advancements in numerical simulation, is no longer suitable for this purpose because the impeller's original shape and structure cannot be altered, and topology optimization would cause such changes. Lightweight compressor impeller design can improve efficiency and service life, but traditional manufacturing methods are no longer able to meet the urgent aerospace demand for lightweight, high-strength, and high-performance products. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a lightweight method for titanium alloy lattice impellers formed by laser selective melting. By designing matching forming process parameters, the complete forming of the lattice structure and the impeller is achieved. The design of the lattice structure enables the impeller to achieve a 20% weight reduction effect, thereby improving the working efficiency and service life of the impeller during service, and achieving the purpose of reducing costs and increasing efficiency for lightweight applications in the aerospace field.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A lightweight method for a titanium alloy lattice impeller formed by selective laser melting comprises the following steps:

[0008] By performing parameterized modeling based on the Gyroid function, a classic implicit function of TPMS, a lattice model with a specific structure is obtained;

[0009] The solid impeller model of the compressor impeller is designed using UG 3D modeling software;

[0010] Performing numerical simulation on the solid impeller model and applying a rotational load to determine the distribution trend of the impeller stress and deformation under high-speed rotation conditions of the solid impeller model;

[0011] Designing the internal cavity of the solid impeller model according to the distribution trend of the impeller stress and deformation, and determining the internal filling area and outer wall thickness of the solid impeller model;

[0012] The solid impeller model is solidly filled with the lattice model having a specific structure to obtain a lattice-filled impeller model;

[0013] Setting the SLM forming lattice impeller process parameters, performing selective laser melting forming on the lattice filling impeller model, and obtaining the laser selective melting simulation results;

[0014] According to the laser selective melting simulation results, the powder discharge holes of the lattice filling impeller model are designed to obtain a lattice structure compressor impeller.

[0015] Preferably, in the parametric modeling based on the Gyroid function, a classic implicit function of TPMS, the porosity of the lattice structure is controlled by changing the parameters of the Gyroid function, and the porosity is adjusted between 35% and 85%.

[0016] Preferably, the Gyroid function is:

[0017]

[0018] When t=0, the porosity of the lattice model is 50%.

[0019] Preferably, when performing numerical simulation on the solid impeller model and applying a rotational load to determine the distribution trend of the impeller stress and deformation of the solid impeller model under high-speed rotation conditions, the impeller stress is maximized at the blade position of the solid impeller model, and the impeller deformation is maximized at the blade edge guide position of the solid impeller model.

[0020] Preferably, according to the distribution trend of the impeller stress and deformation, the internal cavity of the solid impeller model is designed to determine the internal filling area and outer wall thickness of the solid impeller model, including: according to the blade position where the impeller stress is maximized and concentrated in the solid impeller model, determining that the wall thickness of the design axis and hub of the impeller is 3 mm, and then filling the internal filling area with a lattice model separately, and then merging it with the impeller shell to avoid discontinuity and damage of the lattice model structure during internal filling.

[0021] Preferably, the solid impeller model is solidly filled with the lattice model with a specific structure, including: selecting a lattice model with a size of 3 mm and a porosity of 50% for solid filling, and retaining a thickness of 0.5 mm in the filling area for smooth connection processing to ensure the continuity and smoothness of the conformal filling of the lattice model structure.

[0022] Preferably, the process parameters for SLM forming the lattice impeller include but are not limited to laser power and scanning speed. The process parameters for SLM forming the lattice model are laser power 210W and scanning speed 1200mm / s, and no contour scanning is performed during the forming process; the process parameters for SLM forming the solid impeller model are laser power 190W and scanning speed 1250mm / s, and contour scanning of the impeller contour is performed during the forming process.

[0023] Preferably, the powder discharge holes are provided at the bottom of the lattice filling impeller model, and the powder discharge holes are arranged symmetrically, and the size of the two powder discharge holes is 4 mm and the depth is 3.5 mm.

[0024] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0025] (1) The present invention provides a lightweight method for a titanium alloy lattice impeller formed by laser selective melting. The internal cavity structure of the compressor impeller is designed by using laser selective melting technology, and the cavity is filled with a lattice structure. Under the provided process parameters, a perfect combination of the lattice structure and the impeller shell is achieved.

[0026] (2) The lattice structure design provided by the present invention can reduce deformation during the impeller forming process, so that the forming surface roughness can reach 8μm and the density can reach 99.96%, achieving a 20% weight reduction effect and realizing the effect of reducing costs and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a flow chart of a lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to the present invention;

[0029] Figure 2 This is a schematic diagram of a solid impeller model provided in Example 1 of the present invention; wherein, Figure 2(a) is a schematic diagram of the solid structure of the solid impeller model. Figure 2 (b) is a cross-sectional view of the solid impeller model;

[0030] Figure 3 This is a numerical simulation prediction diagram after the impeller provided in the first embodiment of the present invention is applied with a rotational load; wherein, Figure 3 (a) is the numerical simulation prediction diagram of impeller stress, Figure 3 (b) is the numerical simulation prediction diagram of impeller deformation;

[0031] Figure 4 This is a design diagram of the internal cavity of the lattice impeller provided in Example 1 of the present invention; wherein, Figure 4 (a) is the design diagram of the impeller internal cavity. Figure 4 (b) is a schematic diagram of entity filling. Figure 4 (c) is the cross-sectional view of the impeller after smooth connection processing;

[0032] Figure 5 A cross-sectional view of a solid impeller after the lattice model is filled in according to the first embodiment of the present invention;

[0033] Figure 6 This is a stress field prediction diagram of a lattice impeller provided in the first embodiment of the present invention;

[0034] Figure 7 This is a deformation prediction diagram of the lattice impeller provided in the first embodiment of the present invention;

[0035] Figure 8 A stress-deformation prediction diagram of a solid impeller provided in the first embodiment of the present invention;

[0036] Figure 9 This is a schematic structural diagram of the powder discharge hole at the impeller position provided in accordance with the present invention. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] The purpose of the present invention is to provide a lightweight method for titanium alloy lattice impellers formed by laser selective melting. By designing matching forming process parameters, the complete forming of the lattice structure and the impeller is achieved. The design of the lattice structure enables the impeller to achieve a 20% weight reduction effect, thereby improving the working efficiency and service life of the impeller during service, and achieving the purpose of reducing costs and increasing efficiency for lightweight applications in the aerospace field.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, the present invention provides a lightweight method for a titanium alloy lattice impeller formed by selective laser melting, comprising the following steps:

[0042] Step 100: Parameterized modeling is performed based on the Gyroid function, a classic implicit function of TPMS, to obtain a lattice model with a specific structure;

[0043] Specifically, in the parametric modeling based on the Gyroid function, a classic implicit function of TPMS, the porosity of the lattice structure is controlled by changing the parameters of the Gyroid function, and the porosity is adjusted between 35% and 85%. The Gyroid function is:

[0044]

[0045] When t=0, the porosity of the lattice model is 50%.

[0046] Step 200: obtaining a solid impeller model of the compressor impeller using UG 3D modeling software;

[0047] The obtained solid impeller model can be referred to Figure 2 (a), its cross-sectional view refers to Figure 2 (b), it can be found that the solid impeller has more space inside for lightweight design.

[0048] Step 300: numerically simulate the solid impeller model and apply a rotational load to determine the distribution trend of the impeller stress and deformation under high-speed rotation of the solid impeller model;

[0049] Specifically, in the numerical simulation of the solid impeller model, a rotating load is applied to determine the distribution trend of the impeller stress and deformation of the solid impeller model under high-speed rotation conditions, referring to Figure 3 (a), it can be found that the maximum impeller stress is concentrated at the blade position of the solid impeller model, referring to Figure 3 (b), it can be found that the maximum deformation of the impeller is concentrated at the blade edge guide position of the solid impeller model.

[0050] Step 400: Designing an internal cavity of the solid impeller model according to the distribution trend of the impeller stress and deformation, and determining the internal filling area and outer wall thickness of the solid impeller model;

[0051] Specifically, the above process includes: according to the maximum concentration of the impeller stress at the blade position of the solid impeller model, in order to ensure the strength of the impeller, the wall thickness of the design axis and hub of the impeller is 3mm to ensure the overall strength of the lattice impeller, and its internal cavity design can refer to Figure 4 (a), specifically: the internal filling area is filled with a lattice model separately, and then merged with the impeller shell to avoid discontinuity and damage in the lattice model structure during internal filling, so that the lattice model structure and the shell are better transitionally combined, thereby having better strength and vibration resistance.

[0052] Step 500: Filling the solid impeller model with the lattice model having the specific structure to obtain a lattice-filled impeller model;

[0053] Specifically, the above process includes: selecting a lattice model with a size of 3 mm and a porosity of 50% Figure 4 (b) Perform solid filling and keep 0.5mm thickness in the filling area for smooth connection, such as Figure 4 (c) shows that the continuity and smoothness of the conformal filling of the lattice model structure can be ensured, and defects such as sharp corners and discontinuities can be prevented during filling, which may lead to stress concentration and other problems. The filling effect diagram is shown in FIG. Figure 5 shown.

[0054] Step 600: setting SLM forming lattice impeller process parameters, performing selective laser melting on the lattice filling impeller model, and obtaining laser selective melting simulation results;

[0055] Specifically, the SLM forming process parameters for the lattice impeller include but are not limited to laser power and scanning speed. The process parameters for SLM forming of the lattice model are laser power 210W and scanning speed 1200mm / s, and no contour scanning is performed during the forming process. The process parameters for SLM forming of the solid impeller model are laser power 190W and scanning speed 1250mm / s, and the impeller contour is contour scanned during the forming process. Contour scanning will perform a separate laser scan on the edge of the part contour after each layer of cross-section is sintered, so that the forming surface accuracy can reach about 8μm. The other process parameters remain the same. With a spot diameter of 0.1mm, a scanning interval of 0.12mm, a powder layer thickness of 0.03mm, and a steel scraper for unidirectional powder spreading, the forming chamber is formed in an environment with high-purity argon as the protective gas. Under these process conditions, the forming density can reach 99.96%, and the surface roughness is about 8μm.

[0056] In addition, the Simufact Additive stress field prediction of the lattice-filled impeller model after laser selective melting is carried out, and the results are as follows Figure 6 The deformation prediction results are shown in Figure 7 As shown in the figure, the high stress areas in the Gyroid impeller during the printing process are mainly concentrated in the middle shrinkage position of the impeller hub and the edge of the blade, compared with the solid impeller as shown in the figure. Figure 8 The stress shown is 1197 MPa and the deformation is 0.96 mm; the stress of the lattice impeller is 1177 MPa and the deformation is 0.13 mm, indicating that the filling of the lattice is more conducive to the formation of the impeller.

[0057] Step 700: Based on the selective laser melting simulation results, design powder discharge holes for the lattice filling impeller model to obtain a lattice structure compressor impeller.

[0058] Specifically, refer to Figure 9 The powder discharge holes are arranged at the bottom of the lattice filling impeller model, and the powder discharge holes are arranged symmetrically. The size of the two powder discharge holes is 4 mm and the depth is 3.5 mm.

[0059] Therefore, compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The method provided by the present invention utilizes the laser selective melting technology to design the internal cavity structure of the compressor impeller and fill the cavity with a lattice structure. Under the provided process parameters, a perfect combination of the lattice structure and the impeller shell is achieved.

[0061] (2) The lattice structure design provided by the present invention can reduce deformation during the impeller forming process, so that the forming surface roughness can reach 8μm and the density can reach 99.96%, achieving a 20% weight reduction effect and realizing the effect of reducing costs and increasing efficiency.

[0062] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A lightweight method for a titanium alloy lattice impeller formed by laser selective melting, characterized in that: The following steps are involved: By performing parameterized modeling based on the Gyroid function, a classic implicit function of TPMS, a lattice model with a specific structure is obtained; The solid impeller model of the compressor impeller is designed using UG 3D modeling software; Performing numerical simulation on the solid impeller model and applying a rotational load to determine the distribution trend of the impeller stress and deformation under high-speed rotation conditions of the solid impeller model; Designing the internal cavity of the solid impeller model according to the distribution trend of the impeller stress and deformation, and determining the internal filling area and outer wall thickness of the solid impeller model; The solid impeller model is solidly filled with the lattice model having a specific structure to obtain a lattice-filled impeller model; Setting the SLM forming lattice impeller process parameters, performing selective laser melting forming on the lattice filling impeller model, and obtaining the laser selective melting simulation results; According to the laser selective melting simulation results, the powder discharge holes of the lattice filling impeller model are designed to obtain a lattice structure compressor impeller.

2. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 1 is characterized in that: In the parametric modeling based on the Gyroid function, a classic implicit function of TPMS, the porosity of the lattice structure is controlled by changing the parameters of the Gyroid function, and the porosity is adjusted between 35% and 85%.

3. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 2, characterized in that: The Gyroid function is: When t=0, the porosity of the lattice model is 50%.

4. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 1 is characterized in that: In the numerical simulation of the solid impeller model, a rotational load is applied to determine the distribution trend of the impeller stress and deformation of the solid impeller model under high-speed rotation conditions. The impeller stress is maximized at the blade position of the solid impeller model, and the impeller deformation is maximized at the blade edge guide position of the solid impeller model.

5. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 4, characterized in that: According to the distribution trend of the impeller stress and deformation, the internal cavity of the solid impeller model is designed to determine the internal filling area and outer wall thickness of the solid impeller model, including: according to the blade position where the impeller stress is maximized and concentrated in the solid impeller model, the wall thickness of the design axis and hub of the impeller is determined to be 3 mm, and then the internal filling area is separately filled with a lattice model, and then merged with the impeller shell to avoid discontinuity and damage of the lattice model structure during internal filling.

6. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 1, characterized in that: The solid impeller model is solidly filled with the lattice model with a specific structure, including: selecting a lattice model with a size of 3 mm and a porosity of 50% for solid filling, and retaining a thickness of 0.5 mm in the filling area for smooth connection processing to ensure the continuity and smoothness of the conformal filling of the lattice model structure.

7. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 1, characterized in that: The process parameters for SLM forming the lattice impeller include but are not limited to laser power and scanning speed. The process parameters for SLM forming the lattice model are laser power 210W and scanning speed 1200mm / s, and no contour scanning is performed during the forming process; the process parameters for SLM forming the solid impeller model are laser power 190W and scanning speed 1250mm / s, and contour scanning of the impeller contour is performed during the forming process.

8. The lightweight method for a titanium alloy lattice impeller formed by selective laser melting according to claim 1, characterized in that: The powder discharge holes are arranged at the bottom of the dot matrix filling impeller model, and the powder discharge holes are arranged symmetrically. The size of the two powder discharge holes is 4 mm and the depth is 3.5 mm.

Images