A forging production process for a crankshaft

Abstract

The present invention relates to the field of crankshaft forging technology, and in particular to a crankshaft forging production process, comprising the following steps: blanking, heating, pre-forging, final forging, trimming, twisting, residual heat quenching, tempering, flaw detection, shot blasting, and rust prevention to obtain a final product. The present invention can separate the forging from the axial plane, the forging mold cavity is shallow, the excess material edge of the forging is small, the material utilization rate is high, the mold stress is low, and the mold life is long; at the same time, using this set of twisting molds, the production cycle is fast, the twisting angle can be adjusted by the mold closing height, and the product scrap rate is low; in addition, the present invention uses residual heat quenching technology, which can save energy, reduce carbon emissions, and increase economic and social benefits while meeting the requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of crankshaft forging, and in particular to a crankshaft forging production process. Background Art

[0002] The crankshaft is the most critical component in the engine. It receives the force from the connecting rod and converts it into torque to drive the engine's accessories. The crankshaft is subjected to bending and torsional loads due to the combined effects of the centrifugal force of the rotating mass, the periodically changing gas inertia, and the reciprocating inertia. Therefore, the crankshaft must have sufficient strength and rigidity.

[0003] The existing Chinese patent with publication number CN201910979153, which can be referenced, discloses a crankshaft forging process, which includes the following steps: (1) blanking, (2) heating, (3) blanking, (4) primary die forging, (5) secondary die forging, (6) final die forging, and (7) flash removal. The prior art solutions in the above process have the following drawbacks: for crankshafts whose balancing blocks are not on the same horizontal plane, direct forging makes it difficult to separate the dies, and the forging die cavity is deep, making it difficult to fill the product, resulting in low material utilization and a short die life.

[0004] Another Chinese patent with the announcement number CN201470801U for reference discloses a special torsion mold for a small crankshaft. The existing technical solution has the following defects: the torsion angle cannot be adjusted, the scrap rate is high, and the production cycle is slow, which affects production efficiency. Summary of the Invention

[0005] The present invention solves the problems of difficulty in parting, low material utilization, short mold life, slow production cycle, unadjustable torsion angle and high product scrap rate in the related technology, and proposes a crankshaft forging production process, in which the forging is parted from the axial plane, the forging mold cavity is shallow, the excess material edge of the forging is small, the material utilization rate is high, the mold stress is low, and the mold life is long; at the same time, by using this set of torsion molds, the production cycle is fast, the torsion angle can be adjusted by the mold closing height, and the product scrap rate is low; in addition, the present invention uses waste heat quenching technology, which can save energy, reduce carbon emissions, and increase economic and social benefits while meeting the requirements.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: A crankshaft forging production process includes the following steps:

[0007] S1. Cutting: Cut the round bar into short blanks that meet the requirements;

[0008] S2. Heating: The short billet is heated to 1150-1250°C;

[0009] S3 pre-forging: The heated short billet is forged into the basic shape of the crankshaft using a pre-cut die to obtain a pre-forged part;

[0010] S4. Final Forging: The pre-forged piece is forged again through the final forging die to obtain a final forging whose dimensions, except for the angular dimensions of the balancing block and the outer contour dimensions of the parting surface, meet the requirements of the product drawing.

[0011] S5. Trimming: Remove excess material from the parting surface of the final forging to obtain a trimmed piece;

[0012] S6. Twisting: The trimmed pieces, all of which have balancing blocks on the same plane, are twisted through a twisting die, creating a specified angle between the balancing blocks to obtain a twisted piece that meets the dimensional requirements of the product drawing.

[0013] S7. Residual heat quenching: The twisted piece is placed into a residual heat quenching tank for residual heat quenching to obtain a residual heat quenched piece;

[0014] S8. Tempering: The residual heat quenched parts are placed in a tempering furnace for tempering to obtain tempered parts with mechanical properties that meet customer requirements;

[0015] S9. Flaw detection: Magnetize the tempered parts and spray them with magnetic particle detection fluid to check if there are any defects in the products;

[0016] S10. Shot blasting: Shot blast the products after flaw detection to remove impurities on the surface of the products and improve the appearance quality of the products;

[0017] S11. Anti-rust: Anti-rust the product after shot blasting, so that the surface of the product is evenly covered with anti-rust liquid to prevent the product from rusting and obtain the final product.

[0018] As a preferred solution, in step S3, the parting surface of the pre-forging mold used is a horizontal parting surface, and the main journal, connecting rod journal, and balance block are symmetrically distributed in the upper and lower pre-forging mold cavities; the material of the pre-forging part completely fills the pre-forging mold cavity, and there is excess material at the parting surface.

[0019] As a preferred solution, in step S4, the parting surface of the final forging mold used is a horizontal parting surface, and the main journal, connecting rod journal, and balance block are symmetrically distributed in the upper and lower final forging mold cavities; the material of the final forging completely fills the final forging mold cavity, and there is excess material at the parting surface.

[0020] As a preferred solution, in step S6, the twisting mold used includes an upper mold assembly and a lower mold assembly, the upper mold assembly is connected to the lower mold assembly through a guide column, the upper mold assembly and the lower mold assembly are both fixedly placed in a mold frame, and the mold frame is fixedly placed in a press.

[0021] As a preferred solution, the upper mold assembly includes a nitrogen spring, a swing arm, a right twist upper mold, a left twist upper mold and a mold pressing block, the cylinder end face of the nitrogen spring is fixedly mounted on the upper base plate, and the piston rod end face of the nitrogen spring is in contact with the upper mold bearing pressure plate; the upper mold bearing pressure plate is connected to the twist upper mold frame and the floating plate by screws and positioned by pins, the floating plate is connected to the upper base plate by bolts, and the floating plate can move up and down along the bolts with the upper mold bearing pressure plate and the twist upper mold frame; the swing arm is fixedly connected to the right twist upper mold and the left twist upper mold respectively, and the other end of the swing arm is provided with a shaft A and a bearing A, and the bearing A is in contact with the upper base plate and can roll along the lower surface of the upper base plate; A shaft B and a shaft C are further provided between the floating plate and the upper die bearing pressure plate, and at least one set of bearings B are provided on the shaft B and the shaft C. The bearings B are in contact with the right and left twist upper die, and the right and left twist upper die can be accurately positioned and rotate along the bearings B; the shape of the cavity formed by the right and left twist upper die is consistent with the upper half cavity of the final forging die; the right and left twist upper die are installed in the twist upper die frame through the die pressing block, and the right and left twist upper die are used in conjunction with the die pressing block and can rotate in the twist upper die frame; the die pressing block is fixed to the twist upper die frame by screws, and the guide column is fixedly placed in the twist upper die frame.

[0022] As a preferred solution, the lower die assembly includes a twist lower die frame, a lower die bearing pressure plate, a lower base plate, a lower die anti-rotation block, and a die pressing block. The lower die bearing pressure plate, the twist lower die frame and the lower base plate are connected by screws and positioned by pins; the lower base plate is fixedly mounted on the lower die support column, and the lower die support column is fixedly connected to the mold frame; an axis B and an axis C are further provided between the lower base plate and the lower die bearing pressure plate, and at least one set of bearings B are provided on the axis B and the axis C, and the bearings B are connected to the right and left sides of the twist lower die and the twist The left side of the lower die is in contact with the right side of the twist lower die, and the right and left side of the twist lower die can be accurately positioned and rotated along the bearing B; the shape of the cavity formed by the right and left side of the twist lower die is consistent with the cavity of the lower half of the final forging die; the right and left side of the twist lower die are installed in the twist lower die frame through the die pressing block and can rotate in the twist lower die frame; the two lower die stop blocks are respectively fixed to the right and left side of the twist lower die by screws, and the die pressing block is fixed to the twist lower die frame by screws.

[0023] As a preferred solution, in step S7, the residual heat quenching temperature is 850-950°C, the temperature of the forging when it leaves the quenching medium is 50-80°C, and the quenching time is 100 seconds to 140 seconds.

[0024] As a preferred solution, in step S8, the forging is tempered within 24 hours after quenching, the tempering temperature in the tempering process is 510-540°C, and the holding time is 2-3 hours.

[0025] Compared with the prior art, the beneficial effects of the present invention are: the present invention can part the forging from the axial plane, the forging mold cavity is shallow, the excess material edge of the forging is small, the material utilization rate is high, the mold stress is low, and the mold life is long; at the same time, using this set of twisting molds, the production cycle is fast, the twisting angle can be adjusted by the mold closing height, and the product scrap rate is low; in addition, the present invention uses waste heat quenching technology, which can save energy, reduce carbon emissions, and increase economic and social benefits while meeting the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic structural diagram of a crankshaft forging exemplified by the present invention;

[0027] Figure 2 This is a flow chart of the crankshaft production process involved in the present invention;

[0028] Figure 3 It is a cross-sectional view of the slider of the twisting process equipment according to the present invention at the top dead center;

[0029] Figure 4 It is a schematic cross-sectional view of the twisting process equipment slider of the present invention at the bottom dead point, i.e., when the tooling mold completes twisting;

[0030] Figure 5 It is a side sectional view of the tooling die for the twisting process of the present invention when the twisting is completed;

[0031] Figure 6 It is a top view of the tooling die for the twisting process involved in the present invention.

[0032] In the picture:

[0033] 1. Upper base plate, 2. Nitrogen spring, 3. Shaft A, 4. Bearing A, 5. Swing arm, 6. Floating plate, 7. Upper die bearing pressure plate, 8. Guide column, 9. Twist-turn upper die frame, 10. Twist-turn lower die frame, 11. Lower die bearing pressure plate, 12. Lower base plate, 13. Shaft B, 14. Bearing B15. Elastic retaining ring for shaft, 16. Lower die stop block, 17. Shaft C, 18. Twist-turn lower die right, 19. Twist-turn lower die left, 20. Twist-turn upper die right, 21. Twist-turn upper die left, 22. Die pressure block, 23. Bolt, 24. Lower die support column. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0037] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0038] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0039] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0040] like Figures 1 to 6 As shown, a crankshaft forging production process includes the following steps:

[0041] S1. Cutting: Cut the round bar into short blanks that meet the requirements;

[0042] S2. Heating: The short billet is heated to 1150-1250°C;

[0043] S3 pre-forging: The short billet after heating is forged into the basic shape of the crankshaft using a pre-forging die to obtain a pre-forged part;

[0044] S4. Final Forging: The pre-forged piece is forged again through the final forging die to obtain a final forging whose dimensions, except for the angular dimensions of the balancing block and the outer contour dimensions of the parting surface, meet the requirements of the product drawing.

[0045] S5. Trimming: Remove excess material from the parting surface of the final forging to obtain a trimmed piece;

[0046] S6. Twisting: The trimmed parts, all of which have balancing blocks on the same plane, are twisted through a twisting die to create a specified angle between the balancing blocks, resulting in a twisted part that meets the dimensional requirements of the product drawing.

[0047] S7. Residual heat quenching: The twisted piece is placed into a residual heat quenching tank for residual heat quenching to obtain a residual heat quenched piece;

[0048] S8. Tempering: The residual heat quenched parts are placed in a tempering furnace for tempering to obtain tempered parts with mechanical properties that meet customer requirements;

[0049] S9. Flaw detection: Magnetize the tempered parts and spray them with magnetic particle detection fluid to check if there are any defects in the products;

[0050] S10. Shot blasting: Shot blast the products after flaw detection to remove impurities on the surface of the products and improve the appearance quality of the products;

[0051] S11. Anti-rust: Anti-rust the product after shot blasting, so that the surface of the product is evenly covered with anti-rust liquid to prevent the product from rusting and obtain the final product.

[0052] In one embodiment, in step S3, the parting surface of the pre-forging mold used is a horizontal parting surface, and the main journal, connecting rod journal, and balancing block are symmetrically distributed in the upper and lower pre-forging mold cavities; the material of the pre-forging part completely fills the pre-forging mold cavity, and there is excess material at the parting surface.

[0053] In one embodiment, in step S4, the parting surface of the final forging mold is horizontal, and the main journal, connecting rod journal, and balancing block are symmetrically distributed in the upper and lower final forging mold cavities; the material of the final forging completely fills the final forging mold cavity, and there is excess material at the parting surface.

[0054] In one embodiment, in step S6, the twist mold used includes an upper mold assembly and a lower mold assembly, and the upper mold assembly is connected to the lower mold assembly through a guide column 8. The guide column 8 cooperates with the lower mold assembly and can move in the lower mold assembly to play a guiding role, so that the upper mold assembly and the lower mold assembly are positioned in the same position and cooperate with each other; the upper mold assembly and the lower mold assembly are both fixedly placed in the mold frame, and the mold frame is fixedly placed in the press.

[0055] In one embodiment, the upper mold assembly includes a nitrogen spring 2, a swing arm 5, a right twist upper mold 20, a left twist upper mold 21 and a mold pressing block 22. The cylinder end face of the nitrogen spring 2 is fixedly mounted on the upper base plate 1, and the piston rod end face of the nitrogen spring 2 is in contact with the upper mold bearing pressure plate 7; the upper mold bearing pressure plate 7 is connected to the twist upper mold frame 9 and the floating plate 6 by screws and positioned by pins, and the floating plate 6 is connected to the upper base plate 1 by bolts 23, and the floating plate 6 can move up and down with the upper mold bearing pressure plate 7 and the twist upper mold frame 9 along the bolts 23; the swing arm 5 is fixedly connected to the right twist upper mold 20 and the left twist upper mold 21 respectively, and the other end of the swing arm 5 is provided with a shaft A3 and a bearing A4, which are fixedly connected to the swing arm 5 by screws and used in conjunction with each other; the bearing A4 is in contact with the upper base plate 1 and can roll along the lower surface of the upper base plate 1; the floating plate 6 A shaft B13 and a shaft C17 are provided between the upper die bearing pressure plate 7. At least one set of bearings B14 are provided on the shaft B13 and the shaft C17. Elastic rings 15 for the shaft are provided on both sides of the bearings B14. The bearings B14 are in contact with the right twist upper die 20 and the left twist upper die 21. The right twist upper die 20 and the left twist upper die 21 can be accurately positioned and rotated along the bearings B14; the shape of the cavity formed by the right twist upper die 20 and the left twist upper die 21 is consistent with the cavity of the upper half of the final forging die; the right twist upper die 20 and the left twist upper die 21 are installed in the twist upper die frame 9 through the die pressing block 22. The right twist upper die 20 and the left twist upper die 21 are used in conjunction with the die pressing block 22 and can rotate in the twist upper die frame 9; the die pressing block 22 is fixed to the twist upper die frame 9 by screws, and the guide column 8 is fixedly placed in the twist upper die frame 9.

[0056] In one embodiment, the lower die assembly includes a twisted lower die frame 10, a lower die bearing pressure plate 11, a lower base plate 12, a lower die anti-rotation block 16, and a mold pressing block 22. The lower die bearing pressure plate 11, the twisted lower die frame 10 and the lower base plate 12 are connected by screws and positioned by pins; the lower base plate 12 is fixedly mounted on the lower die support column 24, and the lower die support column 24 is fixedly connected to the mold frame; a shaft B13 and a shaft C17 are further provided between the lower base plate 12 and the lower die bearing pressure plate 11, and at least one set of bearings B14 are provided on the shafts B13 and C17, and shaft elastic retaining rings 15 are provided on both sides of the bearings B14. 14 is in contact with the right twist lower die 18 and the left twist lower die 19, which can be accurately positioned and rotated along the bearing B14; the shape of the cavity formed by the right twist lower die 18 and the left twist lower die 19 is consistent with the cavity of the lower half of the final forging die; the right twist lower die 18 and the left twist lower die 19 are installed in the twist lower die frame 10 through the die pressing block 22 and can rotate in the twist lower die frame 10; the two lower die stop blocks 16 are respectively fixed to the right twist lower die 18 and the left twist lower die 19 by screws, and the die pressing block 22 is fixed to the twist lower die frame 10 by screws.

[0057] In one embodiment, in step S7, the residual heat quenching temperature is 850-950° C., the temperature of the forging when it exits the quenching medium is 50-80° C., and the quenching time is 100 seconds to 140 seconds.

[0058] In one embodiment, in step S8, the forging is tempered within 24 hours after quenching, and the tempering temperature in the tempering process is 510-540° C., and the holding time is 2-3 hours.

[0059] The working principle of the twisting mold used in the twisting process provided in this embodiment is as follows:

[0060] like Figure 3 As shown in the figure, it is the initial state of the twisting process equipment at the top dead center. The trimmed forging is placed on the twisting lower die (twisting lower die right 18 and twisting lower die left 19) shown in the figure. The equipment slider starts to move downward, driving the upper base plate 1 to move. At the same time, the upper base plate drives the nitrogen spring 2 to push the floating plate 6, the upper die bearing pressure plate 7, the guide column 8, the twisting upper die frame 9 and the twisting upper die (twisting upper die right 20 and twisting upper die left 21) downward until the twisting upper die is completely fitted with the twisting lower die, as shown in the figure. Figure 2 As shown; the upper base plate 1 then drives the nitrogen spring 2 to continue to move downward. At this time, the piston rod of the nitrogen spring 2 begins to compress, prompting the bearing A4 to drive the swing arm 5 to slide on the lower surface of the upper base plate 1, thereby causing the swing arm 5 to drive the right and left twisting dies to rotate in the forward and backward directions respectively, until the slider moves downward to the bottom dead center, completing the twisting of the crankshaft. Adjusting the bottom dead center position of the press slider also adjusts the crankshaft twist angle, which can effectively control the twisting accuracy of the crankshaft, as shown in the figure. Figure 5 shown.

[0061] Then the slider moves upward, and the upper base plate 1 moves upward with the nitrogen spring 2. The piston rod of the nitrogen spring 2 gradually extends until the bolt 23 contacts the floating plate 6, and the floating plate 6, the upper die bearing pressure plate 7, the guide column 8, the twist upper die frame 9 and the twist upper die are pulled upward to separate the twist upper die and the twist lower die until the slider moves upward to the top dead center and stops. The twisted crankshaft is taken out, and the twist upper and lower dies are reset to complete the twisting process of the crankshaft.

[0062] The present invention provides a crankshaft forging production process, which, on the one hand, can split the crankshaft forging from the axial plane, resulting in a shallow forging mold cavity, small excess material edge of the forging, high material utilization rate, low mold stress, and long mold life; on the other hand, using this set of twisting molds, the production cycle is fast, the twisting angle can be adjusted by the mold closing height, and the product scrap rate is low; furthermore, the present invention uses residual heat quenching technology, which can save energy and reduce production costs while meeting the requirements.

[0063] The above are preferred embodiments of the present invention. Those skilled in the art to which the present invention belongs can also change and modify the above embodiments. Therefore, the present invention is not limited to the above specific embodiments. Any obvious improvements, replacements or modifications made by those skilled in the art on the basis of the present invention fall within the scope of protection of the present invention.

Claims

1. A crankshaft forging production process, characterized in that: The following steps are involved: S1. Cutting: Cut the round bar into short blanks that meet the requirements; S2. Heating: Heat the short billet to 1150~1250℃; S3 pre-forging: The short billet after heating is forged into the basic shape of the crankshaft using a pre-forging die to obtain a pre-forged part; S4. Final Forging: The pre-forged piece is forged again through the final forging die to obtain a final forging whose dimensions, except for the angular dimensions of the balancing block and the outer contour dimensions of the parting surface, meet the requirements of the product drawing. S5. Trimming: Remove excess material from the parting surface of the final forging to obtain a trimmed piece; S6. Twisting: The trimmed pieces, all of which have balancing blocks on the same plane, are twisted through a twisting die, creating a specified angle between the balancing blocks to obtain a twisted piece that meets the dimensional requirements of the product drawing. S7. Residual heat quenching: The twisted piece is placed into a residual heat quenching tank for residual heat quenching to obtain a residual heat quenched piece; S8. Tempering: The residual heat quenched parts are placed in a tempering furnace for tempering to obtain tempered parts with mechanical properties that meet customer requirements; S9. Flaw detection: Magnetize the tempered parts and spray them with magnetic particle detection fluid to check if there are any defects in the products; S10. Shot blasting: Shot blast the products after flaw detection to remove impurities on the surface of the products and improve the appearance quality of the products; S11. Anti-rust: Anti-rust the product after shot blasting, so that the surface of the product is evenly covered with anti-rust liquid to prevent the product from rusting and obtain the final product; In step S6, the twisting mold used includes an upper mold assembly and a lower mold assembly, the upper mold assembly and the lower mold assembly are connected via a guide column (8), the upper mold assembly and the lower mold assembly are fixedly placed in a mold frame, and the mold frame is fixedly placed in a press; The upper die assembly comprises a nitrogen spring (2), a swing arm (5), a right twist upper die (20), a left twist upper die (21) and a die pressing block (22); the cylinder end face of the nitrogen spring (2) is fixedly mounted on the upper base plate (1); the piston rod end face of the nitrogen spring (2) contacts the upper die bearing pressure plate (7); the upper die bearing pressure plate (7) is connected to the twist upper die frame (9) and the floating plate (6) by screws and is positioned by pins; the floating plate (6) is fixed by bolts (23) is connected to the upper base plate (1), and the floating plate (6) can move up and down along the bolt (23) with the upper die bearing pressure plate (7) and the twist upper die frame (9); the swing arm (5) is fixedly connected to the twist upper die right (20) and the twist upper die left (21), respectively, and the other end of the swing arm (5) is provided with a shaft A (3) and a bearing A (4), and the bearing A (4) is in contact with the upper base plate (1) and can roll along the lower surface of the upper base plate (1); the floating plate (6) and A shaft B (13) and a shaft C (17) are provided between the upper die bearing pressure plate (7), and at least one set of bearings B (14) are provided on each of the shafts B (13) and C (17). The bearings B (14) are in contact with the right twist upper die (20) and the left twist upper die (21). The right twist upper die (20) and the left twist upper die (21) can be accurately positioned and rotated along the bearings B (14); the shape of the cavity formed by the right twist upper die (20) and the left twist upper die (21) is consistent with the final shape. The upper half of the forging die has the same cavity; the right twist upper die (20) and the left twist upper die (21) are installed in the twist upper die frame (9) through the die pressing block (22); the right twist upper die (20) and the left twist upper die (21) cooperate with the die pressing block (22) and can rotate in the twist upper die frame (9); the die pressing block (22) is fixedly installed on the twist upper die frame (9) by screws, and the guide column (8) is fixedly placed in the twist upper die frame (9).

2. The crankshaft forging production process according to claim 1, characterized in that: In step S3, the parting surface of the pre-forging mold used is horizontal, and the main journal, connecting rod journal, and balancing block are symmetrically distributed in the upper and lower pre-forging mold cavities; the material of the pre-forging part completely fills the pre-forging mold cavity, and there is excess material at the parting surface.

3. The crankshaft forging production process according to claim 1, characterized in that: In step S4, the parting surface of the final forging mold is horizontal, and the main journal, connecting rod journal, and balancing block are symmetrically distributed in the upper and lower final forging mold cavities; the material of the final forging completely fills the final forging mold cavity, and there is excess material at the parting surface.

4. The crankshaft forging production process according to claim 1, characterized in that: The lower die assembly comprises a twisted lower die frame (10), a lower die bearing pressure plate (11), a lower base plate (12), a lower die anti-rotation block (16), and a die pressing block (22). The lower die bearing pressure plate (11), the twisted lower die frame (10) and the lower base plate (12) are connected by screws and positioned by pins. The lower base plate (12) is fixedly mounted on the lower die support column (24), and the lower die support column (24) is fixedly connected to the die frame. A shaft B (13) and a shaft C (17) are further provided between the lower base plate (12) and the lower die bearing pressure plate (11). At least one set of bearings B (14) are provided on each of the shafts B (13) and C (17). The bearings B (14) are connected to the right side of the twisted lower die (1 8) and the left twist lower die (19), the right twist lower die (18) and the left twist lower die (19) can be accurately positioned and rotated along the bearing B (14); the shape of the cavity formed by the right twist lower die (18) and the left twist lower die (19) is consistent with the cavity of the lower half of the final forging die; the right twist lower die (18) and the left twist lower die (19) are installed in the twist lower die frame (10) through the die pressing block (22) and can rotate in the twist lower die frame (10); the two lower die stop blocks (16) are fixedly installed in the right twist lower die (18) and the left twist lower die (19) by screws, and the die pressing block (22) is fixedly installed on the twist lower die frame (10) by screws.

5. The crankshaft forging production process according to claim 1, characterized in that: In step S7, the residual heat quenching temperature is 850-950°C, the temperature of the forging when it leaves the quenching medium is 50-80°C, and the quenching time is 100 seconds to 140 seconds.

6. The crankshaft forging production process according to claim 1, characterized in that: In step S8, the forging is tempered within 24 hours after quenching. The tempering temperature in the tempering process is 510-540° C. and the holding time is 2-3 hours.

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