A differential extrusion coupled secondary correction integrated forming method for complex profile components with variable curvature

Abstract

The present invention provides a differential extrusion-coupled secondary correction integrated forming method for complex profile components with variable curvature, which can achieve one-time precise forming of complex profile structures with variable curvature, and belongs to the technical field of light alloy material forming. The curved profile structure forming of the material is achieved by a dual-channel differential speed extrusion method, and the secondary correction of the curvature of the curved extruded profile is achieved by the adjustable die mouth of the extrusion device. This method couples the one-time integral extrusion bending forming and the secondary correction method, which can efficiently form complex structures with variable curvature, reduce forming defects such as product rebound and wrinkling, and effectively improve the bending forming accuracy. At the same time, it greatly reduces the process complexity of the curved profile structure forming, which plays a role in reducing costs and increasing efficiency for the high-precision batch production of products.

Description

Technical Field

[0001] The present application relates to the field of light alloy profile forming, and is a differential extrusion coupled secondary correction integrated forming method for complex profile components with variable curvature. Background Art

[0002] Lightweighting vehicles is one of the most direct and effective measures to address energy issues and mitigate the greenhouse effect. It can reduce curb weight while ensuring vehicle strength and safety. The application of new materials and processes is the primary means of achieving lightweighting. Light alloys, due to their superior specific strength, good corrosion resistance, light weight, and excellent formability, and the fact that they can reduce weight by 10% to 60% compared to traditional materials, have become ideal materials for lightweighting vehicles. They are widely used in structural components in aerospace, rail transit, and other fields. With the development of integrated vehicle structures, the demand for profiles has increased significantly. Furthermore, using integral profiles instead of traditional spliced ​​structures can significantly improve the fatigue strength and stress corrosion cracking resistance of light alloys. Compared to straight profiles, curved profiles significantly reduce the amount of joining and welding work required. Therefore, the production of integral profile components with complex curvatures is a trend in the development of load-bearing vehicle structures.

[0003] At present, the mainstream process for curved profiles is the two-step forming process of "extrusion + subsequent bending", such as stretch bending, press bending, and stretch-press composite bending. However, during the bending process, profiles may suffer from forming defects such as springback and wrinkling. These defects will affect the precision and performance of the formed products, thereby increasing production costs and reducing production efficiency. The differential extrusion process can achieve the integrated forming of extruded profile components. This technology combines the characteristics and advantages of ordinary extrusion and equal-diameter angular extrusion, and adjusts the curvature of the profile by controlling the extrusion speed of the upper and lower rods. However, the curvature of the curved profiles actually produced does not meet the target curvature, which reduces the dimensional accuracy of the profile and affects subsequent production applications. Summary of the Invention

[0004] To address these issues, the present invention discloses a differential extrusion-coupled, secondary correction integrated forming method for complex, variable-curvature profile components. This method, while simultaneously forming the curved profile structure, incorporates a fixed, rotatable correction device at the exit of the extrusion barrel to achieve secondary correction of the curvature of the curved, extruded profile. This forming method, combining a one-time, integrated extrusion-bending method with a secondary correction method, enables efficient forming of complex, variable-curvature structures, reducing defects such as springback and wrinkling during the extrusion process. It improves the dimensional accuracy, mechanical properties, and fatigue resistance of the curved profile, while significantly reducing the process complexity of forming the curved profile structure.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] A forming method that can change the bending curvature of complex profile components: introducing the patented design of differential speed control, adjusting the extrusion speeds V1 and V2 of the upper and lower extrusion rods, and realizing the curved profile structure forming of the material through a dual-channel differential speed extrusion method; fixed rivets are installed on the outer end of the extrusion cylinder at the outlet and on the corrective device, and the extrusion cylinder and the corrective device are fixed by a crank and connecting rod mechanism. The middle part of the device is hollow, and its radius is the same as the radius of the blank at the outlet of the extrusion cylinder. It is connected to the channel at the outlet of the extrusion cylinder to perform secondary bending and correction on the profile.

[0007] Furthermore, in order to achieve the effect of adjustable curvature, the forming method described above that can control the bending curvature of the profile connects two equal-diameter angular extrusion cylinders together, that is, there are two extrusion inlets, forming an extrusion channel for differential extrusion, constituting a complete mold cavity, and realizing dual-channel differential speed extrusion.

[0008] Furthermore, the extrusion device of the forming method is composed of two extrusion cylinders, each of which is equipped with an extrusion rod and an extrusion gasket. The extrusion directions of the two extrusion rods are both toward the inside of the extrusion device, that is, the two extrusion forces are in opposite directions.

[0009] Furthermore, the alloy billet enters from both ends of the extrusion cylinder respectively, pushing the extrusion rod to apply load to the billet for extrusion. The billet is extruded from the extrusion channel to the connection between the two extrusion cylinders. At this time, a strong force occurs between the billet and the inner wall of the extrusion cylinder. At the same time, it is constrained by the extrusion channel, and the billet will turn to flow in the direction of the extrusion cylinder outlet, thereby causing the flow direction of the billet to change by 90°.

[0010] Furthermore, by adjusting the extrusion speeds V1 and V2 of the extrusion rod, the bending direction of the molding material at the outlet of the extrusion cylinder can be changed, so as to achieve the purpose of changing the bending curvature of the profile.

[0011] Furthermore, the orthopedic device and the extrusion cylinder are connected by a connecting rod and a crank. The connection between the crank and the connecting rod is movably connected and can rotate, driving the orthopedic device to move in the extrusion direction of the profile and rotate in a plane perpendicular to the extrusion direction.

[0012] Furthermore, the orthopedic device can adjust the curvature of the extruded profile, and the connecting rod mechanism can drive the orthopedic device and the profile to deflect together, thereby realizing an integrated complex curved profile structure with adjustable curvature.

[0013] After the billet is extruded from the exit of the extruder, it enters the correction device for secondary bending correction. Using a connecting rod mechanism, the correction device can rotate and move the billet together, continuously and rapidly deflecting to change the curvature of the exit profile, obtaining an overall curved profile that meets the curvature requirements.

[0014] Beneficial effects of the present invention:

[0015] 1. This invention, applied to the technical field of light alloy forming, enables the precise, one-time formation of complex, variable-curvature, integral profile structures. Curved profile structures are formed through dual-channel, variable-speed extrusion, while a corrective device simultaneously achieves secondary correction of the curved profile's curvature. The entire forming process is simple to operate, with the deflection angle of the corrective device adjusted by controlling the swing amplitude of the connecting rod mechanism.

[0016] 2. This forming method couples one-time integral extrusion bending forming with secondary correction, which can efficiently form complex structures with variable curvature as a whole, with less workload for connection and welding. At the same time, it avoids defects such as springback, wrinkling, and reduced contour accuracy during the secondary bending process, improves the dimensional accuracy and mechanical properties of the product, and makes the grain size of the aluminum alloy more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the material microstructure before and after forming ((a) original microstructure; (b) microstructure after deformation);

[0018] Figure 2 A schematic diagram of the complete extrusion process of this application;

[0019] Figure 3 Schematic diagram of the orthotic device.

[0020] List of reference numerals: 1 - extrusion cylinder; 2 - extrusion blank; 3 - extrusion gasket; 4 - extrusion rod 1; 5 - extrusion rod 2; 6 - crank 1; 7 - connecting rod; 8 - crank 2; 9 - rivet fixing point; 10 - orthotic device; 11 - mold cavity. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively. Example

[0022] Combine Figure 2 and Figure 3, shown is a schematic diagram of an overall test device that can achieve adjustable curvature of bent profiles, the device includes: an extrusion cylinder 1, an extruded alloy billet 2, an extrusion gasket 3, extrusion rods 4 and 5, crank one 6 and crank two 8, a connecting rod 7, a rivet fixing point 9, an orthopedic device 10, and a mold cavity 11 of the orthopedic device.

[0023] The forming method proposed in this application is used to produce solid, integrally bent AA6061 aluminum alloy bars. The cross-sectional shapes at both the inlet and outlet of the extrusion barrel are circular, and the extrusion rod within the barrel can move up and down along the extrusion channel, pushing the billets in the direction of the extrusion force, i.e., billet 1 moves downward and billet 2 moves upward.

[0024] In this embodiment, the extrusion cylinder 1, the extrusion rod 1 4, the extrusion rod 2 5 and the extrusion gasket are in close contact to form a complete extrusion die cavity.

[0025] During specific use, the forming process is carried out at high temperature. The billet enters the extrusion cylinder 1, and the two extrusion rods are used to apply load to the billet. At this time, the billet flows downward at a speed of V1, and the billet flows upward at a speed of V2. The fluidity of the material is better at high temperature, which is conducive to the smooth progress of the extrusion process.

[0026] When used specifically, the direction of movement of the extrusion rod is Figure 1 The movement direction of V1 and V2 is shown. This forming process is equivalent to two equal-diameter angular extrusions and belongs to forward extrusion. The friction coefficient in the die cavity is optimally 0.2 to 0.4. Graphite lubricant can be used to lubricate the inner wall of the extrusion barrel to reduce the friction coefficient.

[0027] In this embodiment, the extrusion cylinder 1 and the billet are in close contact, the billet is constrained by the extrusion cylinder 1 during movement, and the forming temperature is high, causing the flow direction of the billet 2 to deflect 90° and start forming to the right.

[0028] During specific use, the two billets interact with each other, causing the flow direction of the material to change, forming a complete rod profile. Under the action of extrusion rod 1 4 and extrusion rod 2 5, it flows toward the outlet of extrusion cylinder 1. At this time, the movement direction of the extrusion rod is perpendicular to the outflow direction of the billet, completing the side extrusion forming process.

[0029] In this embodiment, by adjusting the speed difference between the extrusion rod 4 and the extrusion rod 5, the flow speed of the blank can be changed to obtain the required integral curved profile component.

[0030] In specific use, by changing the speed difference between the extrusion rod 4 and the extrusion rod 5, the blank can be deflected toward the extrusion rod with a slower speed. That is, when V1>V2, the blank will be deflected toward the extrusion rod 5.

[0031] In this embodiment, the extrusion cylinder 1 and the orthopedic device 10 are connected by cranks 6, 8 and a connecting rod 7. The cranks 6, 8 and the connecting rod 7 are connected by a rotating shaft, which can drive the orthopedic device 10 to rotate.

[0032] During specific use, the blank will continue to move forward along the direction of the extrusion outlet under the action of the extrusion force and enter the mold cavity 11 of the orthopedic device 10. At this time, the connecting rod mechanism can drive the orthopedic device 10 and the extruded blank to deflect a certain angle to achieve the purpose of secondary correction, and finally prepare an integral curved profile component that meets the curvature requirements.

[0033] Working Principle: During the forming process, the billet is first fed into the extrusion barrel 1, which pushes the extrusion rods 1 4 and 2 5. A load is applied to initiate the flow of the billet within the extrusion barrel 1. When the extrusion barrel 1 and the billet come into contact, a strong interaction occurs, causing the billet's flow direction to deflect by 90°. Simultaneously, the speed difference between the extrusion rods 1 4 and 2 5 is adjusted, producing a single, fully curved profile. The extruded billet is then fed into the die cavity 11 of the orthopedic device 10. The connecting rods 6, 7, and 8 simultaneously deflect the orthopedic device 10 and the billet, achieving a secondary correction of the extruded profile. This forming method achieves adjustable profile curvature in two main ways. First, the curvature of the profile is adjusted by varying the speed difference between V1 and V2. The extruded profile at the die exit bends toward the slower extrusion barrel. For example, when V1 > V2, the extruded profile bends downward. Second, the orthopedic device deflects the extruded profile together. This process can be fully automated, enabling the production of profile components with arbitrary deflection.

[0034] like Figure 1 As shown in the figure, before deformation, there are grains of different sizes in the material, with larger grains in some areas and smaller grains in some areas; after deformation, the grain size of the material is more uniform, and the grains are distributed in an equiaxed shape. The more uniform grain distribution is beneficial to improving the corrosion resistance of the material, extending the service life of the material, and ensuring the production quality and safety of the formed structural parts.

[0035] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A differential extrusion coupled secondary correction integrated forming method for complex profile components with variable curvature, characterized in that: The curved profile of the material is formed by dual-channel extrusion at different speeds. A correction device is installed at the outlet of the extrusion cylinder to drive the extruded profile to deflect in any direction, thereby achieving secondary correction of the entire curved profile and forming a curved profile component with the required curvature. The specific steps include: Step 1: Heat the alloy billet to the test temperature; Step 2: The alloy billet is placed in an extrusion die, wherein the extrusion rods arranged opposite to each other on the extrusion die move in opposite directions. Due to the constraint of the upper cylinder wall of the extrusion die, the flow direction of the billet is deflected by 90 degrees, and the alloy profile is extruded forward; Step 3: The extruded alloy profile enters the mold cavity (11) of the orthopedic device (10), wherein the orthopedic device (10) is connected to the discharge end of the extrusion die by adjusting the connecting rod mechanism; in the initial stage of extrusion, the orthopedic device and the discharge end of the extrusion die are tightly fitted, and as the extrusion process proceeds, the orthopedic device can be moved in the direction of profile extrusion by adjusting the swing angle of the connecting rod mechanism. At this time, the connecting rod mechanism can simultaneously drive the orthopedic device (10) and the profile to deflect in any direction in a plane perpendicular to the extrusion outlet direction, and the deflection angle is less than 90°, which can be An integral curved profile component meeting production conditions is obtained; the forming method is carried out at a temperature of 450°C-530°C, and the alloy billet will soften; the alloy billet needs to be placed in an extrusion die in advance, and the extrusion die has two extrusion cylinders (1), wherein billet one and billet two are fed in from both ends of the extrusion cylinder (1); double-channel extrusion is achieved, and extrusion rod one (4) and extrusion rod two (5) apply loads at the same time to promote the flow of the billet; the method of applying loads at both ends causes the two extrusion rods to push the billet to flow at different speeds, and regulates the speed of the extrusion rods The speed difference between the first (4) and the second (5) extrusion rod can change the flow speed of the two blanks to achieve the purpose of changing the curvature of the profile and realize the one-time accurate forming of the complex variable curvature profile structure; the swing of the adjusting connecting rod mechanism can drive the correction device (10) to achieve secondary correction of the extruded profile. The connecting rod mechanism can drive the correction device (10) to move. In the initial stage of extrusion, the correction device (10) moves in the direction of profile extrusion. During extrusion, the correction device (10) can rotate in any direction. The adjusting connecting rod mechanism includes the crank one (6) , connecting rod (7), crank 2 (8) and rivet fixing point (9); wherein a plurality of rivet fixing points (9) are evenly arranged on the outer surface of the orthopedic device (10); a plurality of rivet fixing points (9) are evenly arranged on the outer surface of the discharge end of the extrusion die; wherein crank 1 (6) and crank 2 (8) are movably connected through the connecting rod (7); the other end of crank 1 (6) is rotatably connected to the rivet fixing point (9) fixed on the extrusion die; the other end of crank 2 (8) is rotatably connected to the rivet fixing point (9) fixed on the surface of the orthopedic device (10).

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