A method of forming a multi-material, non-homogeneous, complex thin-walled metal component

Abstract

The present application belongs to the technical field of thin-walled metal component forming manufacturing, and discloses a forming method of a multi-material non-homogeneous complex thin-walled metal component, which comprises the following steps: component analysis requirement; blank design; mold tooling design; pre-blank preparation; pre-blank bulging forming; and post-processing of the bulging component. The forming method can efficiently and quickly realize the preparation of the complex thin-walled metal component under the premise of ensuring the component area performance and forming size precision, and has low cost. The forming method solves the problems of poor forming performance of the traditional tailor-welded blank and long processing cycle, high cost and the problem that the laser beam cannot act on the end surface of the component due to the deformation of the component caused by residual stress when the existing laser metal deposition technology is used to prepare a large-size complex thin-walled component, thereby the continuous printing of the thin-walled component cannot be completed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thin-walled metal component forming manufacturing, and particularly relates to a forming method of a multi-material non-homogeneous complex thin-walled metal component. BACKGROUND

[0002] With the progress of aerospace technology, to meet the development requirements of high Mach number, high performance and high reliability of new generation of aircraft and its engines, the demand for large-size complex thin-walled metal components is increasing, and due to the functional requirements of specific areas, different materials are often used in the feature area of the component, which is manifested as in-plane non-homogeneous materials, customized connection of different strength, different thickness and different metal materials, to realize the optimization of component material design and performance improvement.

[0003] The existing preparation of such large-size non-homogeneous material complex thin-walled components usually adopts two forming processes of first block stamping forming and then welding or first tailor-welding blanking and then hot air pressure forming. The biggest advantage of the first block stamping forming and then welding process is that different thickness, different material or surface state blanks can be freely matched, and the stamping material thickness, material strength and corrosion resistance and other functions can be optimized and configured according to the shape and function of each part of the part on the stamping blank. However, since the formed component is welded from multiple smaller stamping parts, the stamping parts are prone to springback during the forming process, which is difficult to control, and in the subsequent welding process, due to the low bending stiffness of the thin plate itself, the initial deformation of the thin plate near the weld is usually bending, which increases the secondary bending moment under the axial tensile load, resulting in a decrease in the structural stiffness of the thin plate, and unstable deformation is prone to occur. The biggest advantage of the first tailor-welding blanking and then hot air pressure forming is also the free matching of blanks of different wall thicknesses or different material properties, and the optimization and configuration of the wall thickness, material and performance of each part of the part. However, due to the large difference between the shape of the pre-blank and the shape of the final component, wrinkles, cracks or uneven wall thickness defects are prone to occur in local areas during hot air pressure forming.

[0004] In the process of tailor-welding, two or more metal blanks of the same material or different materials, equal thickness or unequal thickness, are connected into a whole by welding method. However, welding is a high heat input process. In the welding process of some unequal thickness or dissimilar metal materials, if the groove structure or related welding parameter design is unreasonable, the heat absorbed by the two plates will be equivalent, resulting in severe deformation at one end and incomplete welding at the other end, which will seriously affect the consistency of the plastic forming quality of tailor-welded blanks in the later stage, and ultimately affect the stability of the performance of the structure. More importantly, after welding, due to the difference in microstructure and mechanical properties between the weld zone and the base metal, the interaction between different regions during deformation leads to difficulty in coordinating the deformation of the weld and the base metal, and it is difficult to regulate the microstructure and properties of the weld zone and the base metal after high temperature deformation. For example, the article "Threadgill P L, Leonard AJ, Shercliff H R, et al. Friction stir welding of aluminium alloys. [J]. International Materials Reviews, 2009, 54(2): 49-93." studies the high temperature deformation behavior of laser welded 2060-T8 aluminum alloy sheets, and finds that the strength of the weld zone after welding is 80% of the base metal, and the elongation is only 1.2%, and all the tensile specimens perpendicular to the weld break at the weld. "Zhang X, Huang T, Yang W, et al. Microstructure and mechanical properties of laser beam-welded AA2060 Al-Li alloy. [J]. Journal of Materials Processing Technology, 2016, 237: 301-308." The article points out that for laser welded and friction stir welded 6082-T6 aluminum alloy sheets, the strength at the weld is reduced by 33% and 25% respectively relative to the base metal, and the tensile specimens perpendicular to the weld also break at the weld. "Wang Z B, He Z B, Fan X B, et al. High temperature deformation behavior of friction stir welded 2024-T4 aluminum alloy sheets. [J]. Journal of Materials Processing Technology, 2017, 247: 184-191." The article studies the high temperature deformation behavior of friction stir welded 2024-T4 aluminum alloy sheets, and finds that at a temperature of 400℃ and a strain rate of 0.001s -1The flow stress and ultimate tensile strength of the tailor-welded joint are lower than that of the base material at the initial strain rate condition. During the uniaxial tensile test and hot gas pressure bulging at high temperature, the deformation is concentrated in the nugget zone of the weld, showing a significant inhomogeneous deformation characteristic. The main strain direction of the weld and the adjacent base material in the tailor-welded blank is perpendicular to each other, and this incompatible deformation behavior leads to poor formability of the tailor-welded blank. The article "Charit I, Mishra R S. High strain rate superplasticity in a commercial 2024 Al alloy via friction stir processing. [J]. Materials Science and Engineering: A, 2003, 359(1-2): 290-296." studies the deformation behavior of 2024 aluminum alloy treated by friction stir welding (300 rpm, 25.4 mm / min). At a comparable temperature and strain rate range, the ductility of the weld is significantly higher than that of the base material. But at a higher temperature, abnormal grain growth occurs in the weld area after the part is formed, and the ductility deteriorates sharply. Therefore, the presence of the weld greatly affects the coordination of the deformation of the weld area and the base material area of the blank at a high temperature.

[0005] At present, laser metal deposition as an advanced additive manufacturing technology has been widely used in the field of aerospace. This technology uses a high-power laser beam to produce a molten pool in the deposition area and continuously melt the metal powder material, and through layer-by-layer deposition to prepare metal components. This technology can form thin-walled components with complex curvature, large cross-section difference and curved axis. However, when using laser metal deposition technology to prepare large-size complex thin-walled metal components, the high temperature gradient and cooling rate will cause uncontrollable deformation of the component, thereby affecting its dimensional accuracy and surface quality. Patent No. (CN201911365925.5) proposes a method for manufacturing thin-walled metal components using 3D printing and hot gas pressure bulging. This method first uses 3D printing to prepare a preform close to the final component, and then obtains the final formed component through hot gas pressure bulging. Although this technology can theoretically prepare multi-material heterogeneous thin-walled parts, the 3D printing process requires the powder to be melted layer by layer, usually with a layer thickness of microns or millimeters. This process has the disadvantages of long processing cycle and high cost. Especially when preparing large-size complex-shaped thin-walled components, the high temperature gradient and cooling rate existing in the additive manufacturing process increase the residual stress inside the printed material. When the deformation amount is large enough, the laser beam cannot act on the end face of the component, thereby failing to complete the continuous printing of the thin-walled component. More importantly, the existing 3D printing has the problems of limited types of applicable materials, high cost of materials, and limited size of manufactured parts.

[0006] Therefore, finding an efficient, controllable, and high-performance forming method for complex thin-walled metal components made of multiple materials with heterogeneity is an urgent problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a forming method for complex thin-walled metal components with multi-material heterogeneity. It utilizes an existing rolled plate / tube A as the substrate material, and additive powder capable of metallurgical bonding is continuously deposited onto the substrate A to form a thin-walled preform composed of the rolled plate / tube A and a powder deposition layer B. Finally, a thin-walled component meeting dimensional accuracy and performance requirements is obtained through subsequent hot gas compression forming. This technology solves the problems of poor forming performance of traditional welded plates, long processing cycles and high costs in the fabrication of large-size complex thin-walled components using existing laser metal deposition technology, and the inability to continuously print thin-walled components due to component deformation caused by residual stress, which prevents the laser beam from acting on the component's end face.

[0008] The technical solution of this invention:

[0009] A method for forming a complex thin-walled metal component with multi-material heterogeneity includes the following steps:

[0010] Step 1, Component Analysis Requirements: Determine the shape and size of the complex thin-walled metal component to be prepared, and analyze the component characteristics to obtain the geometric features of the complex feature areas and the overall geometry of the component's exterior. The preform is prepared by additive manufacturing of the original rolled sheet / tube and local feature areas. The overall shape of the component's exterior is achieved by subsequent hot gas pressure forming process to achieve overall gas expansion forming.

[0011] Step 2: Design the billet: Based on the analysis results of Step 1, determine the materials of the required rolled plate / tube A and the additive powder. The materials are determined according to the functional requirements of specific areas of the component, and the materials between different areas need to achieve good metallurgical bonding. Also, determine the materials, contour shape and deposition process parameters of the areas to be laser metal deposition, including: laser power, laser scanning path, laser scanning speed and powder feed rate.

[0012] Step 3: Mold and tooling design: Based on the analysis results of Step 2, determine the displacement constraint mold for the rolled plate / tube to prevent large-sized billets from deforming due to uneven heating during the laser metal deposition process, which would cause the deposition process to be unable to continue.

[0013] Step 4: Preform preparation: Based on the analysis results of Steps 1, 2 and 3, the rolled plate / tube A is fixed on the working platform as the substrate material, and the laser head continuously deposits on the substrate of the rolled plate / tube A to obtain a preform composed of the rolled plate / tube substrate A and the powder deposition layer B;

[0014] Step 5: Preform Expansion Forming: Heat the hot gas expansion forming mold to reach the set temperature. Place the preform obtained in Step 4 after partial additive forming into the expansion forming mold, close the mold, and then fill the tube blank with high-pressure gas medium to cause the preform to expand and deform and adhere to the mold cavity to obtain the required outer contour. At the same time, keep the mold closed so that the formed component stays under high temperature and high pressure for a certain period of time. Reduce the gas pressure inside or on the surface of the component to the set value and reduce the mold temperature to the set value before taking out the formed component.

[0015] Step 6: Post-processing of bulging components: Remove the process sections from the thin-walled metal components after hot gas bulging, and perform necessary deburring, polishing and cleaning on the ends and surfaces of the components to obtain the final complex thin-walled metal components required.

[0016] The beneficial effects of this invention are:

[0017] (1) The present invention provides a forming method for a multi-material heterogeneous complex thin-walled metal component. It uses an existing rolled plate / tube A as the substrate material, and a powder layer capable of metallurgical bonding is continuously deposited on the substrate A to form a thin-walled preform composed of the rolled plate / tube A and the powder deposition layer B. Finally, the formed component is obtained through hot gas pressure bulging. This technology solves the problems of poor forming performance of traditional welded plates and the long processing cycle, high cost, and inability to continuously print thin-walled components due to residual stress causing component deformation and preventing the laser beam from acting on the component's end face.

[0018] (2) The forming method of a multi-material heterogeneous complex thin-walled metal component of the present invention can combine the complex features of the laser metal deposition layer B with the simple / complex features of the large-size substrate material A, thereby achieving material design optimization and performance improvement. In addition, regions A and B can achieve a continuous and smooth transition, especially for the combination of regions A and B with variable wall thickness, which is easier to achieve.

[0019] (3) The forming method of a multi-material heterogeneous complex thin-walled metal component of the present invention can efficiently and quickly prepare complex thin-walled metal components while ensuring the regional performance and forming dimensional accuracy of the component, and at a low cost. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the forming method of a complex thin-walled metal component with multi-material heterogeneity.

[0021] Figure 2 This is a schematic diagram of the rolled tube A of the present invention.

[0022] Figure 3This is a schematic diagram of the rolled tube A of the present invention constrained by the mold.

[0023] Figure 4 This is a schematic diagram of the laser metal deposition process using rolled tube A as the substrate material in this invention.

[0024] Figure 5 This is a schematic diagram of the preform of the present invention.

[0025] Figure 6 This is a schematic diagram of the preform expansion forming process of the present invention.

[0026] Figure 7 This is a schematic diagram of the complex thin-walled metal component that is finally formed according to the present invention.

[0027] In the figure: 1 Rolling tube A, 2 Constraint mold, 3 Deposition layer B, 4 Working platform, 5 Rotary spindle, 6 Laser head, 7 Powder feeder, 8 Powder nozzle, 9 Preform, 10 Mold cavity, 11 Thermoforming mold, 12 Air source, 13 Forming component. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0029] Example 1: Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 This invention provides a method for forming complex thin-walled metal components with multi-material heterogeneity. The method is carried out according to the following steps:

[0030] Step 1, Component Feature Analysis: Determine the shape and size of the complex thin-walled metal component to be prepared, and analyze the component features to obtain the geometric features of the complex feature areas and the overall geometry of the component's exterior. The preform is prepared by additive manufacturing of the original rolled sheet / tube and local feature areas. The overall shape of the component's exterior is achieved by the subsequent hot gas pressure forming process to achieve overall gas expansion forming.

[0031] Step 2: Design the billet: Based on the analysis results of Step 1, determine the material TA2 for the required rolled tube A and the material TA15 titanium alloy powder for the additive powder, as well as the contour shape and deposition process parameters of the area to be processed by laser metal deposition, including: laser power of 1000-1600w, laser single-layer lifting amount of 0.2-0.5mm, powder feeding speed of 6g / min-10g / min, and laser scanning speed of 400mm / min-800mm / min;

[0032] Step 3: Mold and tooling design: Based on the analysis results of Step 2, determine the displacement constraint mold for the rolled tube A to prevent deformation due to uneven heating during laser metal deposition, which could cause the deposition process to stop.

[0033] Step 4: Preform preparation: Based on the analysis results of steps 1, 2 and 3, the rolled tube TA2 is fixed on the working platform as the base material, and the laser head deposits on the TA2 base to obtain a preform composed of the base TA2 and the deposited layer TA15.

[0034] Step 5: Preform Expansion Forming: Heat the hot gas expansion forming mold to reach the set temperature. Place the preform obtained in Step 4 after partial additive forming into the expansion forming mold, close the mold, and then fill the tube blank with high-pressure gas medium to cause the preform to expand and deform and adhere to the mold cavity to obtain the required outer contour. At the same time, keep the mold closed so that the formed component stays under high temperature and high pressure for a certain period of time. Reduce the gas pressure inside or on the surface of the component to the set value and reduce the mold temperature to the set value before taking out the formed component.

[0035] Step 6: Post-processing of bulging components: Remove the process sections from the thin-walled metal components after hot gas bulging, and perform necessary deburring, polishing and cleaning on the ends and surfaces of the components to obtain the final complex thin-walled metal components required.

[0036] Using existing rolled tube TA2 as the substrate material, a powder layer TA15, which can achieve metallurgical bonding with the substrate, is continuously deposited on the TA2 substrate to form a thin-walled preform composed of the rolled tube TA2 and the powder deposition layer TA15. Finally, the formed component is obtained through hot gas pressure bulging. This technology solves the problems of poor forming performance of traditional welded plates and the long processing cycle, high cost, and the inability to continuously print thin-walled components due to component deformation caused by residual stress, which prevents the laser beam from acting on the end face of the component. In addition, while ensuring the regional performance and forming dimensional accuracy of the component, it can efficiently and quickly realize the preparation of complex thin-walled metal components at a lower cost.

[0037] Example 2: In step four, the metallurgical bonding area between region A and region B of the prepared preform is pretreated by grinding. Other steps are the same as in Example 1.

[0038] By grinding the metallurgical bonding area between region A and region B, the subsequent hot gas pressure expansion is ensured to improve the forming quality of the metal components.

[0039] Example 3: Combination Figure 6Note that in step five, a high-frequency induction heating device is used to heat the mold to 650-850℃. The other steps are the same as in Example 1.

[0040] Heating the titanium alloy tube blank to about 600°C in a short time, within the stress relief range, improves the plasticity of the blank, enhances the material's deformation capacity, and significantly reduces deformation resistance. When preparing metal tubes, heating the mold changes the bulging temperature of the preform, and the high temperature softens the preform, thereby reducing the maximum pressure required for forming.

[0041] Example 4: Combination Figure 7 Note that in step six, the formed bulging component is cut locally using wire cutting, then the surface and ends of the component are polished using fine sandpaper, and then the surface is cleaned using ultrasonic waves. Other steps are the same as in Example 1.

[0042] When removing localized materials using wire cutting, the machining allowance is small, the precision is high, the production cost is low, and valuable materials can be effectively saved; polishing the surface and ends of components with fine sandpaper can improve the dimensional and geometric accuracy of the components and make the surface smoother; ultrasonic cleaning can remove impurities from the surface.

Claims

1. A method of forming a multi-material, non-homogeneous, complex thin-walled metal component, characterized in that, The steps are as follows: Step one, component analysis: determine the shape and size of the complex thin-walled metal component to be prepared, and analyze the features of the complex thin-walled metal component to obtain the geometric features of the complex feature area of the complex thin-walled metal component and the overall geometric shape of the complex thin-walled metal component. The preform is prepared by original rolling plate or original rolling pipe and additive manufacturing in the complex feature area. The overall shape of the component is realized by subsequent hot air forming process. Step two, design the blank: according to the analysis results of step one, determine the material of the rolling plate A or the rolling pipe A and the material of the additive powder. The material is determined according to the needs of the specific area of the complex thin-walled metal component, and the materials between different areas need to realize good metallurgical bonding. In addition, the material, contour shape and deposition process parameters of the laser metal deposition area need to be determined, including laser power, laser scanning path, laser scanning speed and powder feeding amount. Step three, mold tooling design: according to the analysis results of step two, determine the displacement constraint mold of the rolling plate A or the rolling pipe A to prevent the large-sized blank from deforming due to uneven heating during laser metal deposition, which may cause the deposition process to stop. Step four, preform preparation: according to the analysis results of steps one, two and three, fix the rolling plate A or the rolling pipe A as the base material on the working platform, and continuously deposit on the base material with the laser head to obtain the preform composed of the rolling plate A or the rolling pipe A and the powder deposition layer B. Step five, preform bulging forming: heat the hot bulging forming mold to reach the set condition, place the preform obtained after local additive forming in step four in the bulging forming mold, close the mold, then fill high-pressure gas medium into the preform, make the preform bulge and deform and adhere to the hot bulging forming mold cavity, obtain the required external contour, and keep the hot bulging forming mold closed to make the formed complex thin-walled metal component stay at high temperature and high pressure for a certain time, reduce the gas pressure inside or on the surface of the complex thin-walled metal component to the set value, and then take out the formed complex thin-walled metal component. Step six, post-processing of bulging component: process section removal is performed on the hot bulging formed complex thin-walled metal component, and deburring, polishing and cleaning treatment are performed on the end and surface of the complex thin-walled metal component as needed to obtain the final required complex thin-walled metal component.

Images