Intermediate rocker arm free-bending forging process

Abstract

The present application relates to the field of automobile parts forging technology, and more particularly to a middle rocker arm free-bending forging process, which upsizes one end of a metal bar stock, which occupies 60-70% of the overall length, into a large end, and the other end into a small end, and then extrudes and finish-forges the blank; wherein, during extrusion, the small end of the blank is placed upwardly inclined, and the large end is placed downwardly inclined, the small end is extruded from the root of the small end, and after deformation, the first rocker arm is preliminarily formed and the end part is ensured to be fully filled, the large end forms a connecting seat and simultaneously flows along the horizontal direction to one side to form the second rocker arm, for the middle rocker arm, the present application overturns the design concept of the inherent symmetrical piece forging process, cancels the blank bending process, the second rocker arm and the connecting seat of the forged piece are formed by extrusion after local upsize, the blank does not deform when the other end of the blank is up-sized, the bending process is saved, and the phenomenon of the middle angle folding or the middle boss being not fully filled in the forged piece is avoided, and the product quality is improved.

Description

Technical Field

[0001] This invention relates to the field of automotive parts forging technology, and in particular to a pressure-bending-free forging process for intermediate rocker arms. Background Technology

[0002] The center rocker arm is a component of the automotive chassis suspension system; its common forged structure is shown in the attached figure. Figure 4 As shown, the forging includes a connecting seat, a first rocker arm, and a second rocker arm. The first and second rocker arms are of roughly the same length and form an angle of approximately 80°-90°. The connecting seat, the first rocker arm, and the second rocker arm all require subsequent machining of through holes. The first rocker arm has a Z-shaped bend. This forging is a complex and difficult-to-form product. Forging is carried out on a 4000T press. The forging steps include upsetting, bending, pre-forging, and final forging. That is, a bar stock with a diameter of φ75 is used, its head is upset, then it is bent from the middle, and then pre-forging and final forging are performed. However, after upsetting in the middle, the diameter becomes larger, and the bending angle needs to be greater than 90°. After bending and forging, two problems are likely to occur: first, at the inner side of the bending (point A), the two arms flow towards the middle, causing folding; second, at the outer side of the bending (point B), the filling is not full. This process not only has many steps, but also has low production efficiency and high labor intensity, resulting in unstable product quality and a high scrap rate for forgings. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a non-pressure bending forging process for intermediate rocker arms. Unlike existing technologies that involve upsetting and bending in the middle, this process uses upsetting and extrusion at one end to form the second rocker arm, reducing the number of steps and improving the quality of the forgings.

[0004] The technical solution adopted by this invention to solve its technical problem is: a forging process for intermediate rocker arms without pressure bending, wherein one end of a metal bar, accounting for 60%-70% of the overall length, is upset into a large end, and the other end is a small end. The upsetting ratio of the large end is 3-3.5. After the large end is upset, it is truncated into a frustum shape. Then, the upset billet is extruded and finally forged. During extrusion, the small end of the billet is placed at an upward tilt and the large end is placed at a downward tilt. At the root of the small end, the small end is deformed after extrusion to initially form the first rocker arm and ensure that the end is fully filled. The large end forms a connecting seat and simultaneously flows to one side in the horizontal direction to form the second rocker arm.

[0005] Preferably, the metal bar is made of 42CrMo alloy steel, and its cross-sectional area is larger than that of the first rocker arm of the forged part.

[0006] Preferably, the diameter of the metal rod is φ80mm.

[0007] Preferably, the height of the large end of the upset is 75mm and the side angle is 70°-80°.

[0008] Preferably, during extrusion, the metal flows out of the mold cavity to form flash, which is removed after final forging.

[0009] Preferably, during extrusion, a first boss is formed at the connecting seat, a groove is formed at the circular end of the first boss, a curved arm is formed at the first rocker arm, a second boss is formed at the end of the curved arm, a straight arm is formed at the second rocker arm, and an elliptical third boss is formed at the end of the straight arm, and the draft angle of the blank is 5.5°.

[0010] Preferably, during the final forging, the groove forging forms a blind hole, the straight arm of the second rocker arm near the connecting seat forms a weight-reducing groove, and the third boss forging forms two cylindrical bosses. The draft angle of the blank is 5.2°.

[0011] The beneficial effects of this invention are as follows: A forging process for intermediate rocker arms without bending is provided, in which one end of a metal bar, accounting for 60%-70% of its overall length, is upset into a large end, and the other end becomes a small end. The upsetting ratio of the large end is 3-3.5, and the large end is frustum-shaped after upsetting. Then, the upset billet is extruded and finally forged. During extrusion, the small end of the billet is placed at an upward tilt, and the large end is placed at a downward tilt. At the root of the small end, the small end deforms after extrusion to initially form the first rocker arm and ensures that the end is fully filled. The large end forms a connecting seat and simultaneously flows to one side in the horizontal direction to form the second rocker arm. For intermediate rocker arms, this invention subverts the design concept of the traditional symmetrical part forging process, eliminates the billet bending process, and the second rocker arm and connecting seat of the forging are formed by partial upsetting and extrusion. The billet does not deform when the other end is upset, eliminating the bending process. At the same time, it avoids the phenomenon of folding at the middle angle of the forging or incomplete filling of the middle boss, thus improving product quality. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the billet after upsetting the bar stock according to the present invention.

[0013] Figure 2 This is a schematic diagram of the structure of the extruded billet.

[0014] Figure 3 yes Figure 2 The left view.

[0015] Figure 4 This is a schematic diagram of the structure of the billet after final forging according to the present invention.

[0016] Figure 5 yes Figure 4 The left view.

[0017] Figure 6 This is an image of the extruded billet simulated using DEFORM software according to the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0019] In this embodiment, the intermediate rocker arm forging process without bending uses a round bar made of 42CrMo alloy steel with a diameter of φ80mm, which is larger than the diameter of the bar in the original technology, making its cross-sectional area larger than that of the first rocker arm in the forged part. The processing technology mainly includes three steps: upsetting, extrusion, and final forging. First, the bar is heated to 1180℃, and the die is heated to 200±50℃. Then, one end of the bar is upset, with the upset end accounting for 60%-70% of the overall length. This end is called the large end, and the other end is called the small end. The upsetting ratio of the large end is required to be greater than, preferably 3-3.5, so as to ensure that the cross-section of the large end is sufficient to form the connecting seat and the second rocker arm during extrusion. In this embodiment, the total length of the bar is 400mm, and a section with a length of 255mm at one end is upset to 75mm. The structure after upsetting is as follows. Figure 1 As shown, after upsetting the large end, it becomes a frustum shape with a side angle of 70°-80°. This angle prevents bending and folding during the upsetting of the large end.

[0020] Then the upset billet is extruded, such as Figure 2 , Figure 3 As shown, during extrusion, the length direction of the billet is along... Figure 2 From the center of the first boss to the center of the second boss, the smaller end is tilted upwards and the larger end is tilted downwards. The flow of metal differs from the root of the smaller end. After being extruded, the smaller end deforms into a Z-shaped bent arm. The end of this bent arm forms the second boss, thus initially forming the first rocker arm and ensuring full filling at the end. The larger end forms the first boss at the connecting seat. The circular end of this first boss has a groove. Simultaneously, the larger end flows horizontally to one side to form a straight arm. The end of this straight arm forms an elliptical third boss, thus initially forming the second rocker arm. The draft angle of this blank is 5.5°.

[0021] In comparison, the original technology involves bending and forging the upset portion in the middle to form the connecting seat. This solution involves upsetting and extruding one end to form the connecting seat and the second rocker arm. Since the connecting seat at point A is formed by the metal flowing outward after being compressed, and the metal at point B flows outward to form the second rocker arm, problems such as folding and incomplete filling will not occur at this position.

[0022] Then the extruded billet is subjected to final forging, such as... Figure 4 , 5As shown, during final forging, the groove forging forms a blind hole, the straight arm of the second rocker arm near the connecting seat forms a weight-reducing groove, and the third boss forging forms two cylindrical bosses. The draft angle of the blank is 5.2°. After final forging, the thickness of the first boss decreases by 2%-3%, the thickness of the first rocker arm decreases by 8%-10%, the thickness of the second boss decreases by 1%-1.5%, the thickness of the second rocker arm decreases by 8%-10%, and the thickness of the third boss decreases by 4%-6%.

[0023] The extruded billet was simulated using DEFORM software as follows: Figure 6 As shown. During extrusion, metal flows out of the die cavity, forming flash, which is removed after final forging.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A pressure-bending-free forging process for an intermediate rocker arm, characterized in that: One end of the metal bar, which accounts for 60%-70% of the overall length, is upset into a large end, and the other end becomes a small end. The upsetting ratio of the large end is 3-3.

5. After upsetting, the large end is truncated into a frustum shape. Then, the upset billet is extruded and finally forged. During extrusion, the small end of the billet is placed at an upward tilt and the large end is placed at a downward tilt. At the root of the small end, the small end is deformed after extrusion to initially form the first rocker arm and ensure that the end is fully filled. The large end forms a connecting seat and simultaneously flows to one side in the horizontal direction to form the second rocker arm. During extrusion, a first boss is formed at the connecting seat, and a groove is formed at the circular end of the first boss. A curved arm is formed at the first rocker arm, and a second boss is formed at the end of the curved arm. A straight arm is formed at the second rocker arm, and an elliptical third boss is formed at the end of the straight arm. The draft angle of the blank is 5.5°. During the final forging, the groove forging forms a blind hole, the straight arm of the second rocker arm near the connecting seat forms a weight reduction groove, and the third boss forging forms two cylindrical bosses. The draft angle of the blank is 5.2°. After the extruded billet undergoes final forging, the thickness of the first boss decreases by 2%-3%, the thickness of the first rocker arm decreases by 8%-10%, the thickness of the second boss decreases by 1%-1.5%, the thickness of the second rocker arm decreases by 8%-10%, and the thickness of the third boss decreases by 4%-6%.

2. The intermediate rocker arm non-pressure bending forging process according to claim 1, characterized in that: The metal bar is made of 42CrMo alloy steel, and its cross-sectional area is larger than that of the first rocker arm of the forged part.

3. The intermediate rocker arm forging process without pressure bending according to claim 2, characterized in that: The diameter of the metal rod is φ80mm.

4. The intermediate rocker arm non-pressure bending forging process according to claim 1, characterized in that: The height of the large end of the upset is 75mm, and the side angle is 70°-80°.

5. The intermediate rocker arm non-pressure bending forging process according to claim 1, characterized in that: During extrusion, metal flows out of the mold cavity, forming flash, which is removed after final forging.

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