Flexible extrusion device and processing method for thin-walled shaft member with special-shaped section

Abstract

The present application is a kind of flexible extrusion device and processing method for thin-walled special-shaped section shaft members, and the technical scheme of the present application aims at the problems that the internal organization performance uniformity of hollow blank obtained by extrusion cannot be accurately controlled, the internal stress distribution is relatively complex, it is more difficult to further improve the size precision of extruded parts, and the long shaft is prone to flexural deformation due to the disordered release of stress in subsequent processing, thereby causing the scrap of hollow rotor shaft. The present application realizes the short-process accurate forming of thin-walled special-shaped section shaft members, and improves the material utilization rate and optimizes the organization and performance through the mutual cooperation of multi-point flexible extrusion assemblies in the flexible extrusion forming process.

Description

Technical Field

[0001] This invention relates to a flexible extrusion device and processing method for thin-walled, irregularly shaped shaft components, belonging to the field of thermal processing technology. Background Technology

[0002] Currently, hollow shaft components under research and in service in China mainly employ either a process path of die forging alloy bars into solid blanks, followed by machining to obtain the final part dimensions, or a process method of directly machining alloy bars into parts. Both of these processes generally suffer from problems such as low material utilization, long processing cycles, and difficulty in controlling the microstructure and properties of the components. Furthermore, because the internal microstructure of hollow shaft components is not sufficiently strengthened, the fatigue life index fails to fully utilize the material's properties, resulting in a significant gap between the fatigue life index and design requirements.

[0003] Titanium alloys, high-strength steels, and high-temperature alloys used in aerospace applications are typical examples of difficult-to-deform alloys with narrow plastic forming process windows. Therefore, it is essential to improve the formability of these alloys to achieve precise deformation control and dimensional accuracy of the final product. With advancements in hollow rotor shaft manufacturing technology abroad, by the 1960s, leading aerospace manufacturers such as General Electric and Pratt & Whitney (USA), Rolls-Royce (UK), and Snecma and Aubudou (France) had transitioned from traditional solid forging machining to hollow extrusion combined with high-intensity spinning. This resulted in forgings with more uniform microstructure and properties, while significantly saving raw materials. Furthermore, the reduction in machining allowances lowered machining cycles and costs. Currently, hollow extrusion and high-intensity spinning technologies for high-performance hollow rotor shafts show promising application prospects. Researchers in aerospace powerhouses such as the UK, US, and Germany have conducted extensive research, and integrated form control forming technology for large-size hollow rotor shafts has achieved mature application.

[0004] Domestic breakthroughs have not yet been made in the hollow extrusion and high-pressure spinning manufacturing technology for titanium alloy rotor shafts. The uniformity of the internal structure and properties of the hollow blanks obtained by extrusion cannot be precisely controlled, and the internal stress distribution is relatively complex. It is difficult to further improve the dimensional accuracy of the extruded parts. The disordered release of stress during subsequent processing can easily lead to the bending deformation of the long shaft, resulting in the scrapping of the hollow rotor shaft. Summary of the Invention

[0005] This invention addresses the shortcomings of the existing technology by providing a flexible extrusion device and processing method for thin-walled irregular cross-section shaft components. Its purpose is to achieve precise forming of thin-walled irregular cross-section hollow shaft components in a short process, while improving material utilization and optimizing microstructure and performance.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The flexible extrusion device for thin-walled irregular cross-section shaft components of the present invention includes an extrusion cylinder 1, an extrusion head 2, and an extrusion rod 5. The extrusion head 2 and the extrusion rod 5 are respectively disposed at both ends of the extrusion cylinder 1. The billet 3 is subjected to the combined action of the extrusion head 2 and the extrusion rod 5 along the axial direction in the extrusion cylinder 1 to form a hollow shaft component. The feature is that an extrusion assembly 4 is provided on the inner wall of the extrusion cylinder 1 and the side of the extrusion rod 5. The extrusion assembly 4 on the inner wall of the extrusion cylinder 1 forms a radial extrusion action on the outer wall surface of the hollow shaft component, and the extrusion assembly 4 on the side of the extrusion rod 5 forms a radial extrusion action on the inner cavity surface of the hollow shaft component.

[0008] The extrusion assembly 4 includes an extrusion ball head 6, a pressure device 7, and a heater 8. The extrusion ball head 6 is mounted on the pressure device 7 and is provided with extrusion force by the pressure device 7. The heater 8 is connected to the pressure device 7 to heat the actuating position of the extrusion ball head 6.

[0009] In practice, the extrusion ball head 6 is made of ultra-high heat-resistant bearing steel, and the extrusion ball head 6 can perform single-pass multi-control, so that any position on the billet 3 can be independently deformed during the extrusion process.

[0010] Furthermore, the extrusion ball head 6 is semi-circular in shape.

[0011] In practice, the extrusion ball heads 6 are evenly distributed in a ring shape along the inner wall of the extrusion cylinder 1, and the inner ring extrusion ball heads 6 are arranged at equal intervals along the axial direction of the inner wall of the extrusion cylinder 1.

[0012] The present invention also proposes a method for processing shaft-like components with the aforementioned thin-walled irregular cross-section using a flexible extrusion device, characterized in that: the thin-walled irregular cross-section shaft-like component is a hollow shaft component, and the steps of the method are as follows:

[0013] Step 1: Preparation of billet

[0014] Based on the dimensions of the hollow shaft component and the coefficient of thermal expansion of the material, the blank 3 is processed and loaded into the extrusion cylinder 1 before extrusion, with the two being a transition fit.

[0015] Step 2: Preparation of the flexible extrusion device

[0016] Assemble the extrusion cylinder 1, extrusion head 2 and extrusion rod 5 and install the extrusion assembly 4. The extrusion cylinder 1, extrusion head 2 and extrusion rod 5 are coaxial. The extrusion ball head 6 in the extrusion assembly 4 is semi-circular in shape and made of ultra-high heat-resistant bearing steel. Set the pressure of the pressure device 7 to zero and start the heater 8 to heat the billet 3 to its plastic deformation temperature.

[0017] Step 3: Flexible Extrusion

[0018] The extrusion head 2 and the extrusion rod 5 move in opposite directions and abut against the billet 3, keeping the extrusion rod 5 stationary. The extrusion head 2 continues to move to the left at a speed of 5-20 mm / s. The extrusion ball heads 6 on the extrusion cylinder 1 are controlled by their respective pressure devices (7), providing and maintaining a pressure of 300-1000 MPa at intervals, while the pressure of the extrusion ball heads 6 at intervals remains zero. All the extrusion ball heads 6 on the extrusion rod 5 are controlled by their respective pressure devices (7), providing and maintaining a pressure of 1000-1500 MPa. In the flexible extrusion forming process, through the cooperation of multiple flexible extrusion components, a hollow shaft component with a wavy outer surface is finally obtained.

[0019] During implementation, in step three, the extrusion ball head 6 on the extrusion cylinder 1 is controlled by its respective pressure device (7) to provide and maintain a pressure of 1000-1500 MPa, and finally obtains a straight cylindrical hollow shaft component.

[0020] In practice, the blank 3 is made of a difficult-to-deform titanium alloy, high-strength steel, or high-temperature alloy.

[0021] The features and beneficial technical effects of the present invention are as follows:

[0022] I. The present invention addresses hollow thin-walled long-axis components by combining extrusion and spinning processes. The extrusion ball head 6 serves as both an extrusion die core and a spinning wheel. Through temperature and pressure control of the multi-point extrusion ball head 6, near-net-shape forming of hollow thin-walled long-axis components can be achieved in one step. The plastic flow lines on the outer and inner surfaces of the formed component are distributed according to the shape. The technical solution of the present invention is called flexible extrusion, which prevents the accumulation of flaw detection allowance and increased difficulty in microstructure control caused by multiple forming processes.

[0023] Second, during the extrusion process, the billet is subjected not only to the axial force applied by the extrusion rod and extrusion head, which causes the billet to change from a cylindrical shape to a hollow tube shape, but also to the radial force applied by the flexible ball head, which causes the outer diameter and inner diameter of the billet to change along the axial direction.

[0024] Third, during the flexible extrusion process, the billet is subjected to both axial and radial forces, integrating the process characteristics of extrusion and spinning, achieving one-fire forming, optimizing the microstructure, and avoiding dry firing;

[0025] IV. During the forming process, a certain point on the billet can be subjected to tensile stress while simultaneously being subjected to compressive stress on the inner and outer surfaces. The plastic streamlines are distributed according to the shape, which improves the fatigue performance of the component.

[0026] 5. The ball head assembly has an auxiliary heater. When radial pressure is applied, as the auxiliary heating temperature increases, the radial force can be transmitted to a thicker blank, resulting in more uniform microstructure deformation. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the flexible extrusion device in the technical solution of the present invention.

[0028] Figure 2 This is a schematic diagram of the extrusion component structure in the technical solution of this invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0030] Referring to Appendices 1 and 2, the flexible extrusion device for thin-walled irregular cross-section shaft components according to the technical solution of the present invention includes an extrusion cylinder 1, an extrusion head 2, and an extrusion rod 5. The extrusion head 2 and the extrusion rod 5 are respectively disposed at both ends of the extrusion cylinder 1. The billet 3 is subjected to the combined action of the extrusion head 2 and the extrusion rod 5 along the axial direction within the extrusion cylinder 1, forming a hollow shaft component. The invention is characterized in that: an extrusion assembly 4 is disposed on the inner wall of the extrusion cylinder 1 and the side of the extrusion rod 5. The extrusion assembly 4 on the inner wall of the extrusion cylinder 1 forms a radial extrusion action on the outer wall surface of the hollow shaft component, and the extrusion assembly 4 on the side of the extrusion rod 5 forms a radial extrusion action on the inner cavity surface of the hollow shaft component; the extrusion ball heads 6 are evenly distributed in a ring shape along the inner wall of the extrusion cylinder 1, and the inner ring extrusion ball heads 6 are arranged at equal intervals along the axial direction of the inner wall of the extrusion cylinder 1.

[0031] The extrusion assembly 4 includes an extrusion ball head 6, a pressure device 7, and a heater 8. The extrusion ball head 6 is mounted on the pressure device 7 and is provided with extrusion force by the pressure device 7. The heater 8 is connected to the pressure device 7 to heat the actuating position of the extrusion ball head 6.

[0032] In this embodiment, the thin-walled irregular cross-section shaft component is a hollow shaft component, and the material of its blank 3 is titanium alloy, high-temperature alloy or high-strength steel. The processing steps of the above-mentioned thin-walled irregular cross-section shaft component flexible extrusion device are as follows:

[0033] Step 1: Preparation of billet

[0034] Based on the dimensions of the hollow shaft component and the coefficient of thermal expansion of the material, the blank 3 is processed and loaded into the extrusion cylinder 1 before extrusion, with the two being a transition fit.

[0035] Step 2: Preparation of the flexible extrusion device

[0036] Assemble the extrusion cylinder 1, extrusion head 2 and extrusion rod 5 and install the extrusion assembly 4. The extrusion cylinder 1, extrusion head 2 and extrusion rod 5 are coaxial. The extrusion ball head 6 in the extrusion assembly 4 is semi-circular in shape and made of ultra-high heat-resistant bearing steel. Set the pressure of the pressure device 7 to zero and start the heater 8 to heat the billet 3 to its plastic deformation temperature.

[0037] Step 3: Flexible Extrusion

[0038] The extrusion head 2 and extrusion rod 5 move in opposite directions and abut against the billet 3, keeping the extrusion rod 5 stationary. The extrusion head 2 continues to move to the left at a speed of 5-20 mm / s. The extrusion ball heads 6 on the extrusion cylinder 1 are controlled by their respective pressure devices 7, providing and maintaining a pressure of 300-1000 MPa at intervals, while the pressure of the extrusion ball heads 6 at intervals remains zero. All the extrusion ball heads 6 on the extrusion rod 5 are controlled by their respective pressure devices 7, providing and maintaining a pressure of 1000-1500 MPa, ultimately obtaining a hollow shaft component with a wavy outer surface.

Claims

1. A method for processing a thin-walled, irregularly shaped shaft component using a flexible extrusion device, comprising an extrusion cylinder (1), an extrusion head (2), and an extrusion rod (5), wherein the extrusion head (2) and the extrusion rod (5) are respectively disposed at both ends of the extrusion cylinder (1), and the blank (3) is subjected to the combined axial action of the extrusion head (2) and the extrusion rod (5) within the extrusion cylinder (1) to form a hollow shaft component, characterized in that: An extrusion assembly (4) is provided on the inner wall of the extrusion cylinder (1) and the side of the extrusion rod (5). The extrusion assembly (4) on the inner wall of the extrusion cylinder (1) forms a radial extrusion action on the outer wall surface of the hollow shaft component, and the extrusion assembly (4) on the side of the extrusion rod (5) forms a radial extrusion action on the inner cavity surface of the hollow shaft component. The extrusion assembly (4) includes an extrusion ball head (6), a pressure device (7), and a heater (8). The extrusion ball head (6) is mounted on the pressure device (7) and is provided with extrusion force by the pressure device (7). The heater (8) is connected to the pressure device (7) to heat the actuation position of the extrusion ball head (6). The extrusion ball head (6) can be controlled in a single stroke, so that any position on the billet (3) can be independently deformed during the extrusion process. The steps of the method are as follows: Step 1: Preparation of billet Based on the dimensions of the hollow shaft component and the coefficient of thermal expansion of the material, the blank (3) is processed and loaded into the extrusion cylinder (1) before extrusion, and the two are in transition fit; Step 2: Preparation of the flexible extrusion device Assemble the extrusion cylinder (1), extrusion head (2) and extrusion rod (5) and install the extrusion assembly (4). The extrusion cylinder (1), extrusion head (2) and extrusion rod (5) are coaxial. The extrusion ball head (6) in the extrusion assembly (4) is semi-circular in shape and made of ultra-strong heat-resistant bearing steel. Set the pressure of the pressure device (7) to zero and start the heater (8) to heat the billet (3) to its plastic deformation temperature. Step 3: Flexible Extrusion The extrusion head (2) and extrusion rod (5) move in opposite directions and abut against the billet (3), keeping the extrusion rod (5) stationary. The extrusion head (2) continues to move to the left at a speed of 5-20 mm / s. The extrusion ball heads (6) on the extrusion cylinder (1) are controlled by their respective pressure devices (7), providing and maintaining a pressure of 300-1000 MPa at intervals, while the pressure of the extrusion ball heads (6) at intervals is kept at zero. All the extrusion ball heads (6) on the extrusion rod (5) are controlled by their respective pressure devices (7), providing and maintaining a pressure of 1000-1500 MPa, ultimately obtaining a hollow shaft component with a wavy outer surface.

2. The method according to claim 1, characterized in that: The extrusion ball head (6) is semi-circular in shape.

3. The method according to claim 1, characterized in that: The extrusion ball heads (6) are evenly distributed in a ring shape along the inner wall of the extrusion cylinder (1), and the inner ring extrusion ball heads (6) are arranged at equal intervals along the axial direction of the inner wall of the extrusion cylinder (1).

4. The method according to claim 1, characterized in that: The extrusion ball head (6) is made of a hard material.

5. The method according to claim 1, characterized in that: In step three, the extrusion ball head (6) on the extrusion cylinder (1) is controlled by its respective pressure device (7) to provide and maintain a pressure of 1000-1500 MPa, and finally obtains a straight cylindrical hollow shaft component.

6. According to the method of claim 1, the material of the billet (3) is a difficult-to-deform titanium alloy, high-strength steel or high-temperature alloy.

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