Secondary forming forging die for high-stability motorcycle balance shaft

Abstract

The utility model discloses a secondary forming forging die for a high-stability motorcycle balance shaft, which comprises a lower die holder, a lower die block, a lower die boss, a lower die block, a lower die block, an upper die boss, a lower die block and a lower die block, and is characterized in that the lower die holder is provided with a pre-forging lower cavity and a finish-forging lower cavity; the upper die base comprises an upper die block and an upper die boss, and a pre-forging upper cavity and a finish-forging upper cavity are formed in the upper die base; and in a die assembly state, the width of a gap between the pre-forging upper cavity and the pre-forging lower cavity is larger than that of a gap between the finish-forging upper cavity and the finish-forging lower cavity. According to the secondary forming forging die for the high-stability motorcycle balance shaft, the gap width between the pre-forging lower cavity and the pre-forging upper cavity is controlled to be larger than the gap width between the finish-forging lower cavity and the finish-forging upper cavity during die assembly, so that the pressure power consumption requirement of pre-forging is reduced, and the forging cost is reduced; and meanwhile, the blank material can conveniently enter the deep positions of the pre-forging upper cavity and the pre-forging lower cavity through pressure, and the finish forging precision and the forging quality can be improved.

Description

Technical Field

[0001] This utility model relates to the field of balance shaft forging technology, and in particular to a secondary forming forging die for a high-stability motorcycle balance shaft. Background Technology

[0002] Balance shaft technology is a widely used technology in automobile and motorcycle engines. Its structure is simple and easy to use, mainly consisting of a main shaft and a balance weight integrally formed outside the main shaft. The balance weight can effectively reduce engine vibration, thereby reducing engine noise and extending engine life.

[0003] In the prior art, such as the Chinese utility model patents with announcement numbers CN217529096U and CN212945210U, a forging die for a balance shaft is disclosed. By opening the pre-forging lower cavity and the final forging lower cavity on the lower die base, and opening the pre-forging upper cavity and the final forging upper cavity on the upper die base, the upper die base and the lower die base can respectively perform pre-forging and final forging treatment on the two blanks after the die is closed, which improves forging efficiency. At the same time, it makes the die structure more compact and reduces costs.

[0004] However, in the aforementioned forging die, the openings of the pre-forging lower cavity and the final forging lower cavity are located on the same horizontal plane, while the openings of the pre-forging upper cavity and the final forging upper cavity are also located on the same horizontal plane. This results in the gap between the pre-forging lower cavity and the pre-forging upper cavity having the same thickness as the gap between the final forging lower cavity and the final forging upper cavity during die closing. Furthermore, the depths of the pre-forging lower cavity and the final forging lower cavity are the same, and the depths of the pre-forging upper cavity and the final forging lower cavity are also the same. This necessitates adjusting the blank between the pre-forging upper cavity and the pre-forging lower cavity, and the gap between the final forging upper cavity and the final forging lower cavity, during die closing. The pressure applied to the billets between the lower cavities is basically the same, which leads to a large power consumption required for forging pressure, increasing forging costs. In addition, during the pre-forging process, the billet material is not easy to penetrate deep into the pre-forging lower and upper cavities, which makes it difficult for the billet material to fill the space between the final forging lower and upper cavities during the final forging, affecting the forging accuracy of the billet and thus reducing the accuracy and stability of the final balance shaft product. Furthermore, the forging process also generates thick flash, which increases the amount of scrap material and further increases forging costs.

[0005] Therefore, it is necessary to improve the forging die for the balance shaft in the existing technology. Utility Model Content

[0006] The purpose of this invention is to overcome the defects in the existing technology and provide a secondary forming forging die for a motorcycle balance shaft that reduces power consumption requirements, thereby reducing forging costs and improving forging precision and quality.

[0007] To achieve the above technical effects, the technical solution of this utility model is: a secondary forming forging die for a high-stability motorcycle balance shaft, comprising:

[0008] The lower die base includes a lower module and a lower die boss integrally formed on the top surface of the lower module. The lower die base is provided with a pre-forging lower cavity and a final forging lower cavity. The cavity openings of the pre-forging lower cavity and the final forging lower cavity are both located on the top surface of the lower die boss.

[0009] The upper die base includes an upper module and an upper die boss integrally formed on the bottom surface of the upper module. The upper die base is provided with a pre-forging upper cavity and a final forging upper cavity for cooperating with the pre-forging lower cavity and the final forging lower cavity, respectively. The cavity openings of the pre-forging upper cavity and the final forging upper cavity are both located on the bottom surface of the upper die boss.

[0010] The lower die holder and the upper die holder are used to connect the mold closing assembly to close and separate the molds. In the mold closing state, the pre-forging upper cavity is directly opposite and adjacent to the upper pre-forging lower cavity, and the final forging upper cavity is directly opposite and adjacent to the upper final forging lower cavity. The gap width between the pre-forging upper cavity and the pre-forging lower cavity is greater than the gap width between the final forging upper cavity and the final forging lower cavity.

[0011] Preferably, in order to ensure that the gap width between the pre-forging upper cavity and the pre-forging lower cavity is greater than the gap width between the final forging upper cavity and the final forging lower cavity during mold closing, the lower mold boss includes an integrally connected pre-forging lower boss and a final forging lower boss, the upper mold boss includes an integrally connected pre-forging upper boss and a final forging upper boss, the top surface of the lower module and the bottom surface of the upper module are both horizontal; the thickness of the pre-forging lower boss is less than the thickness of the final forging lower boss, and / or the thickness of the pre-forging upper boss is less than the thickness of the final forging upper boss.

[0012] Preferably, in order to ensure uniform stress on the upper and lower die holders and extend the service life of the die, the thickness of the pre-forged lower boss is less than the thickness of the final forged lower boss, and the thickness of the pre-forged upper boss is less than the thickness of the final forged upper boss.

[0013] Preferably, in order to ensure forging accuracy, the thickness difference between the final forging lower boss and the pre-forging lower boss, as well as the height difference between the final forging upper boss and the final forging lower boss, are both 0.3-0.7 mm.

[0014] Preferably, in order to facilitate the entry of the billet material into the pre-forging upper cavity, pre-forging lower cavity, final forging upper cavity, and final forging lower cavity during forging, the cavity walls of the pre-forging lower cavity and the final forging lower cavity are both connected to the top surface of the lower die boss via a circular arc transition, and the cavity walls of the pre-forging upper cavity and the final forging upper cavity are both connected to the bottom surface of the upper die boss via a circular arc transition.

[0015] Preferably, in order to improve forging accuracy, the transition connection radius between the pre-forging lower cavity wall and the top surface of the lower die boss is greater than the transition connection radius between the final forging lower cavity wall and the top surface of the lower die boss, and the transition connection radius between the pre-forging upper cavity wall and the bottom surface of the upper die boss is greater than the transition connection radius between the final forging upper cavity wall and the bottom surface of the upper die boss.

[0016] Preferably, in order to facilitate the material filling the lower and lower cavities of the final forging during final forging and improve forging accuracy, the cavity depth of the pre-forging lower cavity is greater than the cavity depth of the lower cavities of the final forging, and the cavity depth of the pre-forging upper cavity is greater than the cavity depth of the upper cavities of the final forging.

[0017] Preferably, in order to further reduce the pressure requirements during forging and lower forging costs, the pre-forging lower cavity and the final forging lower cavity are adjacent to each other, and the openings of the pre-forging lower cavity and the final forging lower cavity are both adjacent to the circumferential outer edge of the lower die boss; the pre-forging upper cavity and the final forging upper cavity are adjacent to each other, and the openings of the pre-forging upper cavity and the final forging upper cavity are both adjacent to the circumferential outer edge of the upper die boss.

[0018] Preferably, in order to facilitate the removal of the billet or product after forging, the lower die base is also provided with a top hole extending in the vertical direction, the top end of the top hole extending upward to the top surface of the lower die boss.

[0019] Preferably, to further facilitate the removal of the billet or product after forging, the top hole is located between the pre-forging lower cavity and the final forging lower cavity.

[0020] In summary, compared with the prior art, the secondary forming forging die for the high-stability motorcycle balance shaft of this utility model reduces the pressure and power consumption requirements of pre-forging and lowers the forging cost by controlling the gap width between the pre-forging lower cavity and the pre-forging upper cavity to be greater than the gap width between the final forging lower cavity and the final forging upper cavity during die closing. At the same time, it facilitates the pressure of the billet material to enter the depth of the pre-forging upper cavity and the pre-forging lower cavity, which is beneficial to improving the final forging accuracy and forging quality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model in the mold-closed state;

[0022] Figure 2 This is a schematic diagram of the structure of this utility model in its molded state;

[0023] Figure 3 This is a schematic diagram of the structure of the lower mold base of this utility model;

[0024] Figure 4 yes Figure 3 Top view;

[0025] Figure 5 This is a schematic diagram of the upper mold base of this utility model;

[0026] Figure 6 yes Figure 5 A bottom view;

[0027] Figure 7 yes Figure 1 A schematic diagram of the cross-sectional structure;

[0028] In the diagram: 1. Lower die holder; 11. Lower module; 12. Lower die boss; 121. Pre-forging lower boss; 122. Final forging lower boss; 13. Pre-forging lower cavity; 14. Final forging lower cavity; 15. Top hole; 2. Upper die holder; 21. Upper module; 22. Upper die boss; 221. Pre-forging upper boss; 222. Final forging upper boss; 23. Pre-forging upper cavity; 24. Final forging upper cavity. Detailed Implementation

[0029] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0030] like Figures 1-7 As shown, the present invention provides a secondary forming forging die for a high-stability motorcycle balance shaft, comprising:

[0031] The lower die base 1 includes a lower module 11 and a lower die boss 12 integrally formed on the top surface of the lower module 11. The lower die base 1 is provided with a pre-forging lower cavity 13 and a final forging lower cavity 14. The cavity openings of the pre-forging lower cavity 13 and the final forging lower cavity 14 are both located on the top surface of the lower die boss 12.

[0032] The upper die base 2 includes an upper module 21 and an upper die boss 22 integrally formed on the bottom surface of the upper module 21. The upper die base 2 is provided with a pre-forging upper cavity 23 and a final forging upper cavity 24 for cooperating with the pre-forging lower cavity 13 and the final forging lower cavity 14, respectively. The cavity openings of the pre-forging upper cavity 23 and the final forging upper cavity 24 are both located on the bottom surface of the upper die boss 22.

[0033] The lower die holder 1 and the upper die holder 2 are used to connect the die closing assembly to close and separate the two dies. In the die closing state, the pre-forging upper cavity 23 is directly opposite and adjacent to the upper pre-forging lower cavity 13, and the final forging upper cavity 24 is directly opposite and adjacent to the upper final forging lower cavity 14. The gap width between the pre-forging upper cavity 23 and the pre-forging lower cavity 13 is greater than the gap width between the final forging upper cavity 24 and the final forging lower cavity 14.

[0034] Specifically, the mold-closing assembly used to connect the lower mold base 1 and the upper mold base 2 in this utility model typically includes a base and a lifting unit (preferably a hydraulic cylinder). The lower mold base 1 is usually fixed above the base, and the upper mold base 2 is positioned directly above the lower mold base 1. The pre-forging upper cavity 23 is directly opposite the pre-forging lower cavity 13, and the final forging upper cavity 24 is directly opposite the final forging lower cavity 14. The upper mold base 2 is connected to the output end of the lifting unit, which controls the lifting and lowering movement of the upper mold base 2. When the upper mold base 2 moves upward to the mold-separating position, the upper mold base 2 and the lower mold base 1 maintain a certain distance. Figure 2 The gaps shown facilitate the placement of billets in the pre-forging lower cavity 13 and the final forging lower cavity 14 of the lower die holder 1, or the removal of pre-forged billets from the pre-forging lower cavity 13 and the final forging lower cavity 14 from the lower die holder 1. The upper die holder 2 moves downward to the die-closing position, and the pre-forging lower cavity 13 and the pre-forging upper cavity 23 cooperate to pre-forge the billet. The final forging lower cavity 14 and the final forging upper cavity 24 cooperate to final forge another billet. In this way, two billets can be pre-forged and final forged simultaneously, improving forging efficiency. Furthermore, the design of two cavities in the lower die holder 1 and the upper die holder 2 makes the structure more compact and reduces forging costs.

[0035] Unlike existing technologies, in this invention, during mold closing, the gap width between the pre-forging lower cavity 13 and the pre-forging upper cavity 23 is greater than the gap width between the final forging lower cavity 14 and the final forging upper cavity 24. This facilitates the material of the billet entering the depth of the pre-forging upper cavity 23 and the pre-forging lower cavity 13 during the pre-forging process, which is beneficial to improving the final forging accuracy and forging quality, and reducing the power consumption required during pre-forging, i.e., reducing the power consumption required for the lifting unit to perform pre-forging processing, and reducing forging costs.

[0036] A further improvement is that the lower die boss 12 includes an integrally connected pre-forging lower boss 121 and a final forging lower boss 122, and the upper die boss 22 includes an integrally connected pre-forging upper boss 221 and a final forging upper boss 222. The top surface of the lower module 11 and the bottom surface of the upper module 21 are both horizontal. The thickness of the pre-forging lower boss 121 is less than the thickness of the final forging lower boss 122, and the thickness of the pre-forging upper boss 221 is less than the thickness of the final forging upper boss 222.

[0037] Specifically, the top surface of the lower die boss 12 and the bottom surface of the upper die boss 22 are both stepped surfaces. The protrusion thickness of the pre-forging lower boss 121 is less than the thickness of the final forging lower boss 122, and the thickness of the pre-forging upper boss 221 is less than the thickness of the final forging upper boss 222. This results in the gap width between the pre-forging lower boss 121 and the pre-forging upper boss 221 being greater than the gap width between the final forging lower boss 122 and the final forging upper boss 222 when the mold is closed. In other words, the distance between the cavity opening of the pre-forging lower cavity 13 and the cavity opening of the pre-forging upper cavity 23 is greater than that between the final forging lower cavity 13 and the cavity opening of the pre-forging upper cavity 23. The distance between cavity 14 and cavity 24 of the final forging cavity reduces the contact area between the lower die holder 1 and the upper die holder 2 during the pre-forging process, thereby reducing the power consumption requirements of pre-forging. Furthermore, there is sufficient clearance during pre-forging to facilitate the entry of the billet material into the interior of the lower pre-forging cavity 13 and the upper pre-forging cavity 23, which is conducive to improving the forging quality. In addition, the top surface of the lower die boss 12 and the bottom surface of the upper die boss 22 are both stepped, which makes the top of the lower die holder 1 and the top of the upper die holder 2 uniformly stressed during the mold closing process, thus extending the service life of the entire mold.

[0038] A further improvement is that the thickness difference between the final forging lower boss 122 and the pre-forging lower boss 121, as well as the height difference between the final forging upper boss 222 and the final forging lower boss 122, are both 0.3-0.7mm.

[0039] Specifically, the thickness of the lower boss 122 in the final forging is 0.5 mm greater than the thickness of the lower boss 121 in the pre-forging, and the thickness of the upper boss 222 in the final forging is 0.5 mm greater than the thickness of the lower boss 122 in the final forging. With the above design, the difference between the gap width between the pre-forging upper cavity 23 and the pre-forging lower cavity 13 and the gap width between the final forging upper cavity 24 and the final forging lower cavity 14 is 1mm when the mold is closed. This avoids the gap between the pre-forging upper cavity 23 and the pre-forging lower cavity 13 being too large or too small after mold closing. If the gap is too large, it will easily affect the accuracy of pre-forging and reduce the quality of final forging. If the gap is too small, it will easily increase the forging pressure and increase the power consumption. At the same time, it is not conducive to the excess material of the billet flowing to the bottom of the upper die holder 2 and the top of the lower die holder 1 during forging to form flash. Therefore, the thickness of the final forging lower boss 122 is 0.5mm greater than the thickness of the pre-forging lower boss 121, and the thickness of the final forging upper boss 222 is 0.5mm greater than the thickness of the final forging lower boss 122. Of course, as a substitute for a similar effect, the thickness difference between the final forging lower boss 122 and the pre-forging lower boss 121, as well as the height difference between the final forging upper boss 222 and the final forging lower boss 122, can all be controlled within 0.3-0.7mm.

[0040] A further improvement is that the cavity walls of the pre-forging lower cavity 13 and the final forging lower cavity 14 are both connected to the top surface of the lower die boss 12 by a circular arc transition, and the cavity walls of the pre-forging upper cavity 23 and the final forging upper cavity 24 are both connected to the bottom surface of the upper die boss 22 by a circular arc transition.

[0041] With the above design, during the forging process, when the die extrudes the billet, the billet material enters the depths of the pre-forging lower cavity 13, the final forging lower cavity 14, the pre-forging upper cavity 23, and the final forging upper cavity 24 through the arc transition corner. It also facilitates the flow of excess material from the above four cavities, forming flash between the top surfaces of the lower die boss 12 and the upper die boss 22, which is convenient for subsequent edge trimming and ultimately improves the quality of the forged product.

[0042] A further improvement is that the transition connection radius between the wall of the pre-forging lower cavity 13 and the top surface of the lower die boss 12 is greater than the transition connection radius between the wall of the final forging lower cavity 14 and the top surface of the lower die boss 12, and the transition connection radius between the wall of the pre-forging upper cavity 23 and the bottom surface of the upper die boss 22 is greater than the transition connection radius between the wall of the final forging upper cavity 24 and the bottom surface of the upper die boss 22.

[0043] Specifically, the transition connection radius between the wall of the pre-forging lower cavity 13 and the top surface of the lower die boss 12, and the transition connection radius between the wall of the pre-forging upper cavity 23 and the bottom surface of the upper die boss 22 are both 0.3mm, which facilitates the material flow of the billet during the pre-forging process. However, the transition connection radius between the wall of the final forging lower cavity 14 and the top surface of the lower die boss 12, and the transition connection radius between the bottom surface of the upper die boss 22 are both greater than the transition connection radius between the wall of the final forging upper cavity 24 and the bottom surface of the upper die boss 22, which is 0.2mm, thus ensuring the final forging accuracy and improving the quality of the forged products.

[0044] A further improvement is that the cavity depth of the pre-forging lower cavity 13 is greater than the cavity depth of the final forging lower cavity 14, and the cavity depth of the pre-forging upper cavity 23 is greater than the cavity depth of the final forging upper cavity 24.

[0045] This design ensures sufficient depth within the pre-forging lower cavity 13 and pre-forging upper cavity 23, facilitating the flow of billet material into these cavities during pre-forging. This improves pre-forging quality and prevents situations where the depth of the pre-forging lower cavity 13 equals the depth of the final forging lower cavity 14, or the depth of the pre-forging upper cavity 23 is greater than the depth of the final forging upper cavity 24. In such cases, the billet material may fail to fill the bottom of the pre-forging upper cavity 23 and pre-forging lower cavity 13 during pre-forging, resulting in incomplete filling of the final forging lower cavity 14 and final forging upper cavity 24 during final forging. This reduces final forging quality and ultimately lowers product quality.

[0046] A further improvement is that the pre-forging lower cavity 13 and the final forging lower cavity 14 are adjacent to each other, and the openings of both the pre-forging lower cavity 13 and the final forging lower cavity 14 are adjacent to the circumferential outer edge of the lower die boss 12; the pre-forging upper cavity 23 and the final forging upper cavity 24 are adjacent to each other, and the openings of both the pre-forging upper cavity 23 and the final forging upper cavity 24 are adjacent to the circumferential outer edge of the upper die boss 22.

[0047] By adopting the above design, the top surface area of ​​the lower die boss 12 and the bottom surface area of ​​the upper die boss 22 are reduced, thereby reducing the contact area between the lower die boss 12 and the upper die boss 22 when the die is closed, reducing the forging power consumption requirements, and thus reducing the forging cost.

[0048] A further improvement is that the lower die base 1 is also provided with a top hole 15 extending in the vertical direction. The top of the top hole 15 extends upward to the top surface of the lower die boss 12. The top hole 15 is located between the pre-forging lower cavity 13 and the final forging lower cavity 14.

[0049] The top hole 15 is a through hole for the ejector pin to pass through. After the lower die holder 1 and the upper die holder 2 are closed and separated, the excess material of the billet flows to the top hole 15 to form a flash. The ejector pin passes through the bottom of the top hole 15 and acts on the flash at the top of the top hole 15. The flash can lift the pre-forged billet and the final forged billet, making it easier for the mechanical claw to grasp and remove the forged workpiece for subsequent processing, such as trimming and shaping.

[0050] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A secondary forming forging die for a high-stability motorcycle balance shaft, characterized in that, include: The lower die base (1) includes a lower module (11) and a lower die boss (12) integrally formed on the top surface of the lower module (11). The lower die base (1) is provided with a pre-forging lower cavity (13) and a final forging lower cavity (14). The cavity opening of the pre-forging lower cavity (13) and the cavity opening of the final forging lower cavity (14) are both located on the top surface of the lower die boss (12). The upper mold base (2) includes an upper module (21) and an upper mold boss (22) integrally formed on the bottom surface of the upper module (21). The upper mold base (2) is provided with a pre-forging upper cavity (23) and a final forging upper cavity (24) for cooperating with the pre-forging lower cavity (13) and the final forging lower cavity (14), respectively. The cavity openings of the pre-forging upper cavity (23) and the final forging upper cavity (24) are both located on the bottom surface of the upper mold boss (22). The lower mold base (1) and the upper mold base (2) are used to connect the mold closing assembly to close and separate the molds. In the mold closing state, the pre-forging upper cavity (23) is directly opposite and adjacent to the pre-forging lower cavity (13) directly above, and the final forging upper cavity (24) is directly opposite and adjacent to the final forging lower cavity (14) directly above. The gap width between the pre-forging upper cavity (23) and the pre-forging lower cavity (13) is greater than the gap width between the final forging upper cavity (24) and the final forging lower cavity (14).

2. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 1, characterized in that: The lower die boss (12) includes a pre-forging lower boss (121) and a final forging lower boss (122) integrally connected. The upper die boss (22) includes a pre-forging upper boss (221) and a final forging upper boss (222) integrally connected. The top surface of the lower module (11) and the bottom surface of the upper module (21) are both horizontal. The thickness of the pre-forging lower boss (121) is less than the thickness of the final forging lower boss (122), and / or the thickness of the pre-forging upper boss (221) is less than the thickness of the final forging upper boss (222).

3. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 2, characterized in that: The thickness of the pre-forged lower boss (121) is less than the thickness of the final forged lower boss (122), and the thickness of the pre-forged upper boss (221) is less than the thickness of the final forged upper boss (222).

4. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 3, characterized in that: The thickness difference between the final forging lower boss (122) and the pre-forging lower boss (121), and the height difference between the final forging upper boss (222) and the final forging lower boss (122) are both 0.3-0.7mm.

5. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 1, characterized in that: The cavity walls of the pre-forging lower cavity (13) and the final forging lower cavity (14) are both connected to the top surface of the lower die boss (12) by a circular arc transition. The cavity walls of the pre-forging upper cavity (23) and the final forging upper cavity (24) are both connected to the bottom surface of the upper die boss (22) by a circular arc transition.

6. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 5, characterized in that: The transition radius between the wall of the pre-forging lower cavity (13) and the top surface of the lower die boss (12) is greater than the transition radius between the wall of the final forging lower cavity (14) and the top surface of the lower die boss (12), and the transition radius between the wall of the pre-forging upper cavity (23) and the bottom surface of the upper die boss (22) is greater than the transition radius between the wall of the final forging upper cavity (24) and the bottom surface of the upper die boss (22).

7. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 5, characterized in that: The cavity depth of the pre-forging lower cavity (13) is greater than the cavity depth of the final forging lower cavity (14), and the cavity depth of the pre-forging upper cavity (23) is greater than the cavity depth of the final forging upper cavity (24).

8. The secondary forming forging die for a high-stability motorcycle balance shaft according to any one of claims 1-7, characterized in that: The pre-forging lower cavity (13) and the final forging lower cavity (14) are adjacent to each other. The openings of the pre-forging lower cavity (13) and the final forging lower cavity (14) are both adjacent to the circumferential outer edge of the lower die boss (12). The pre-forging upper cavity (23) and the final forging upper cavity (24) are adjacent to each other. The openings of the pre-forging upper cavity (23) and the final forging upper cavity (24) are both adjacent to the circumferential outer edge of the upper die boss (22).

9. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 8, characterized in that: The lower mold base (1) is also provided with a top hole (15) extending in the vertical direction, and the top of the top hole (15) extends upward to the top surface of the lower mold boss (12).

10. The secondary forming forging die for a high-stability motorcycle balance shaft according to claim 9, characterized in that: The top hole (15) is located between the pre-forging lower cavity (13) and the final forging lower cavity (14).

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