Hollow half-shaft reducing die

Abstract

The utility model discloses a hollow half shaft reducing die, which belongs to the field of manufacturing of automobile parts and comprises an upper die, a lower die, a lower die, a lower die, a lower die and an upper pressing head. The upper die is connected with external pressurizing equipment, and the upper pressing head is used for limiting and abutting against a workpiece to be machined; the lower die is located under the upper die, the lower die comprises a hole shrinkage die body, and the upper die and the lower die are matched to press a workpiece to be machined into the hole shrinkage die body for hole shrinkage; the lower die further comprises a righting assembly, the righting assembly is located over the reducing die body, and the righting assembly is used for enabling a workpiece to be machined to enter the reducing die body at a fixed angle. The centering assembly is arranged to apply inward radial holding force to the to-be-machined part, so that the to-be-machined part is always kept at the correct axial position in the moving process in the lower die, the conditions that the end of the cold-rolled steel pipe is broken, the pipe wall is thinned and the like after diameter shrinkage are avoided, and the diameter shrinkage forming quality can be guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of automotive parts manufacturing, and more specifically, to a hollow half-shaft diameter reduction mold. Background Technology

[0002] The half-shaft of a car, also known as the drive shaft, is the shaft that connects the differential to the drive wheels. As a part that transmits torque in a car, the half-shaft has mandatory requirements for its torsional strength. In the industry, half-shafts are generally made by solid shaft forging, which results in relatively high weight. However, with the current national advocacy for energy conservation and emission reduction, reducing vehicle weight is a development trend, and solid half-shafts can no longer meet the needs of industry development. Therefore, the hollowing process of half-shafts has naturally become a cutting-edge technology discussed in the industry.

[0003] To improve raw material utilization and reduce the risk of defects such as center hole eccentricity and uneven wall thickness during deep hole machining of half-shafts, the relevant technology uses cold-rolled steel tubes to form hollow half-shafts by reducing their diameter. However, due to the limitation of material deformation, cold-rolled steel tubes cannot be reduced to the required diameter in one step and require multiple reductions to form hollow half-shafts. After the first reduction, the cold-rolled steel tubes are special-shaped tubes with different inner diameters. In subsequent reduction steps, when the cold-rolled steel tubes with different diameters move in the mold, due to the gap between them and the mold, the cold-rolled steel tubes are prone to being in a skewed position in the mold, which leads to cracks at the ends of the cold-rolled steel tubes after reduction, thinning of the tube walls, and affecting the forming quality. Utility Model Content

[0004] The purpose of this invention is to solve the technical problem that when cold-rolled steel pipes of different diameters move in the diameter reduction mold, their axial angle is in a skewed state, resulting in poor diameter reduction forming quality. Therefore, a hollow half-shaft diameter reduction mold is proposed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A hollow half-shaft diameter reduction mold, comprising:

[0007] The upper mold is connected to an external pressurizing device, and the upper mold is provided with an upper pressure head for limiting and abutting the workpiece to be processed;

[0008] The lower die is located directly below the upper die. The lower die includes a diameter reduction die body. The upper die and the lower die cooperate to press the workpiece to be processed into the diameter reduction die body for diameter reduction.

[0009] The lower mold further includes a straightening component, which is located directly above the diameter reduction mold body. The straightening component is used to keep the workpiece at a fixed angle when it enters the diameter reduction mold body.

[0010] Furthermore, the upper mold also includes:

[0011] An upper pad, wherein the upper pad has a concave structure and the concave surface of the upper pad faces downward;

[0012] The upper pressure head cover is detachably connected to the lower part of the upper pad block, and the interior of the upper pressure head cover is provided with a space for fixing the upper pressure head.

[0013] Furthermore, the upper pressure head includes:

[0014] Connector, the connector being connected to the inside of the upper pressure head jacket;

[0015] The abutting end face is located below the upper pressure head outer sleeve, and the abutting end face is provided with a groove that matches the shape of the workpiece to be processed.

[0016] Furthermore, the reducing die body is provided with a reducing through hole, the diameter of which gradually decreases from one end face to the other end face of the reducing die body; the lower die also includes:

[0017] An upper pressure ring is connected above the straightening assembly and located on the outside of the straightening assembly;

[0018] The lower die pull ring has a tubular structure, and its inner diameter matches the outer diameter of the upper pressure ring. The reducing die body, the straightening component, and the upper pressure ring are connected inside the lower die pull ring. The lower die pull ring is attached to and pressed against the upper pressure ring above the upper pressure ring.

[0019] The lower mold cavity is connected directly below the lower mold pull ring, and an accommodating space is provided inside the lower mold cavity;

[0020] A straightening assembly is disposed within the lower mold cavity and located below the diameter reduction mold body;

[0021] A lower pad assembly is disposed within the lower mold cavity to fix the position of the straightening assembly within the lower mold cavity;

[0022] A lower pressure ring is sleeved on the outer side of the lower mold cavity and the lower mold pull ring, and presses the lower mold pull ring tightly above the lower mold cavity.

[0023] Furthermore, the straightening component includes:

[0024] A guide cover, which has a cylindrical structure and a through hole, is connected above the main body of the diameter reduction die, such that the axis of the diameter reduction through hole and the through hole on the guide cover are on the same straight line. The guide cover is used to limit the outward expansion of the workpiece to be processed.

[0025] A pressure plate, which is in the shape of a cover, is detachably connected to the upper surface of the guide cover, and the gap between the pressure plate and the guide cover forms a track;

[0026] A slider is located within a track between the pressure plate and the guide cover; the three-lobed slider is circumferentially arranged along the edge of the through hole on the guide cover.

[0027] A spring clamp abuts against the outside of the three-lobed slider, bringing the three-lobed slider closer together.

[0028] Furthermore, the main body of the diameter reduction mold adopts a double-layer structure of inner and outer molds, including:

[0029] The inner mold has a reduced-diameter through hole located at the center of the end face of the inner mold.

[0030] An outer mold is fitted over the outer side of the inner mold. The outer mold and the inner mold are joined by heat sealing. The outer mold is used to provide inward prestress to the inner mold.

[0031] Furthermore, the straightening component includes:

[0032] A guide sleeve, which has a tubular structure, is disposed inside the lower mold cavity and located below the diameter reduction mold body. The guide sleeve is positioned corresponding to the diameter reduction through hole, so that the axis of the guide sleeve and the axis of the diameter reduction through hole are on the same straight line.

[0033] The lower mold guide sleeve is sleeved on the outside of the guide sleeve to limit the deformation of the guide sleeve.

[0034] Furthermore, the lower pad assembly includes:

[0035] The first lower pad is located at the bottom of the lower mold cavity;

[0036] The second lower pad is disposed above the first lower pad and below the lower mold guide sleeve and the straight guide sleeve. The straight guide sleeve is limited and fixed between the second lower pad and the diameter reduction mold body.

[0037] The third lower pad is disposed between the diameter reduction die body and the lower die guide sleeve, and cooperates with the second lower pad to press and fix the lower die guide sleeve.

[0038] The beneficial effects of this utility model are as follows: The hollow half-shaft diameter reduction mold provided in this application applies an inward radial clamping force to the workpiece through the straightening component, so that the workpiece is always kept in the correct axial position during the movement of the workpiece in the lower mold, thereby avoiding end cracking, thinning of the tube wall and other situations after the workpiece is diameter reduced, and the diameter reduction forming quality can be guaranteed. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of a hollow half-shaft diameter reduction mold provided in an embodiment of the present utility model;

[0040] Figure 2 This is an enlarged view of the straightening component structure in an embodiment of this utility model.

[0041] The markings in the diagram are as follows:

[0042] 1. Upper mold; 11. Upper pad block; 12. Upper pressure head sleeve; 13. Upper pressure head; 131. Connector; 132. Abutment end face;

[0043] 2. Lower mold; 21. Reduction mold body; 211. Inner mold; 212. Outer mold; 22. Straightening assembly; 221. Guide cover; 222. Pressure plate; 223. Slider; 224. Spring clamp; 23. Upper pressure ring; 24. Lower mold pull ring; 25. Lower mold cavity; 26. Straightening assembly; 261. Straightening sleeve; 262. Lower mold guide sleeve; 27. Lower pad assembly; 271. First lower pad; 272. Second lower pad; 273. Third lower pad; 28. Lower pressure ring. Detailed Implementation

[0044] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0045] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0046] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0047] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0048] In this embodiment, the workpiece to be processed is a pre-treated cold-rolled steel pipe. The pre-treatment steps include, but are not limited to, blanking, normalizing, shot blasting, lubrication, and diameter reduction of the cold-rolled steel pipe; for further details, please refer to [link to relevant documentation]. Figures 1 to 2 The embodiment of this application shown provides a hollow half-shaft diameter reduction mold. In practical applications, the hollow half-shaft diameter reduction mold is used to further reduce the diameter of the cold-rolled steel pipe obtained after diameter reduction, thereby changing the diameter of the cold-rolled steel pipe to achieve the required size.

[0049] The hollow half-shaft diameter reduction mold includes: an upper mold 1 and a lower mold 2 located directly below the upper mold 1; the upper mold 1 includes: an upper pad block 11, an upper pressure head sleeve 12, and an upper pressure head 13; more specifically, the upper pad block 11 has a concave structure, with the concave surface of the upper pad block 11 facing downwards, and its upper surface is connected to an external pressurizing device. The upper pad block 11 moves synchronously with the external pressurizing device to transmit the pressure applied by the external pressurizing device. In this embodiment, the external pressurizing device is a press.

[0050] The upper pressure head sleeve 12 has a columnar structure. The upper pressure head sleeve 12 is detachably connected to the lower part of the upper pad block 11 by bolts. The interior of the upper pressure head sleeve 12 is provided with a space for fixing the upper pressure head 13.

[0051] The upper pressure head 13 is the main load-bearing component in the upper die 1. Its cross-section is T-shaped. The upper pressure head 13 is made of Cr12MoV material and has a heat treatment hardness of 58 to 62 HRC. The upper pressure head 13 includes a connector 131 and an abutment end face 132. The connector 131 is located in the internal space of the upper pressure head outer sleeve 12. In the above technical solution, the connector 131 is provided with a screw hole. The upper pressure head 13 is fixed to the upper pressure head outer sleeve 12 by threading a bolt into the screw hole of the connector 131. The abutment end face 132 is located below the upper pressure head outer sleeve 12. The abutment end face 132 is provided with a groove that matches the shape of the end of the cold-rolled steel pipe. The cold-rolled steel pipe is fixed to the upper pressure head 13 by abutting against the groove of the abutment end face 132.

[0052] The lower die 2 includes: a reducing die body 21, a straightening assembly 22, an upper pressure ring 23, a lower die pull ring 24, a lower die cavity 25, a straightening assembly 26, a lower pad assembly 27, and a lower pressure ring 28; wherein, the reducing die body 21 is generally annular in structure, with a reducing through hole in its middle, and the diameter of the reducing through hole gradually decreases from one end face of the reducing die body 21 to the other end face. The large end diameter of the reducing through hole on the reducing die body 21 matches the diameter of the unreduced part of the cold-rolled steel pipe, and its small end diameter is determined according to the diameter of the cold-rolled steel pipe. The diameter reduction requirement of the pipe is set, and the end face of the large end of the diameter reduction through hole on the diameter reduction die body 21 is set upward and close to the upper die 1. The diameter reduction die body 21 is the main component for reducing the diameter of cold-rolled steel pipe. The lower die 2 cooperates with the upper die 1 to press the cold-rolled steel pipe into the diameter reduction die body 21 for diameter reduction. Specifically, the part of the cold-rolled steel pipe to be reduced enters the diameter reduction die body 21 from the large end of the diameter reduction through hole. During the process of passing through the diameter reduction through hole, the outer diameter gradually decreases until the part to be reduced completely passes through the small end of the diameter reduction through hole, and the diameter reduction is completed.

[0053] In a preferred embodiment of this application, the diameter reduction die body 21 adopts a double-layer structure of inner and outer molds, including: an inner mold 211 and an outer mold 212; the inner mold 211 is made of hard alloy material, and the diameter reduction through hole is opened at the center of the end face of the inner mold 211. The inner surface of the diameter reduction through hole is polished and the roughness Ra is within 0.2; the outer mold 212 is sleeved on the outside of the inner mold 211, and is made of 40Cr material with a hardness of 28 to 32 HRC. The outer mold 212 and the inner mold 211 are joined by heat sealing, and the contour junction is smoothly transitioned; the outer mold 212 provides inward prestress to the inner mold 211 to ensure that the inner mold 211 can apply sufficient clamping force to the cold-rolled steel pipe and avoid the inner mold 211 being cracked by the cold-rolled steel pipe during the diameter reduction process.

[0054] The straightening assembly 22 is located directly above the reducing die body 21 and is used to maintain the cold-rolled steel pipe at a fixed angle and in the correct axial position when it enters the reducing die body 21; please refer to Figure 2The straightening assembly 22 includes: a guide cover 221, a pressure plate 222, a slider 223, and a spring clamp 224. The guide cover 221 has a cylindrical structure with a through hole in its middle that allows the cold-rolled steel pipe to pass through. The diameter of the through hole on the guide cover 221 matches the diameter of the large end of the diameter reduction through hole. The guide cover 221 is connected above the diameter reduction die body 21, and the axis of the diameter reduction through hole and the through hole on the guide cover 221 are on the same straight line. The cold-rolled steel pipe passes through the guide cover 221 and enters the diameter reduction die body 21 for diameter reduction. The guide cover 221 plays a guiding role during the diameter reduction movement of the cold-rolled steel pipe, while restricting the outward expansion of the cold-rolled steel pipe.

[0055] Because when the cold-rolled steel pipe of different diameters moves in the through hole on the guide cover 221, there is a gap between the reduced diameter part and the guide cover 221, which causes the cold-rolled steel pipe to pass through the guide cover 221 at an angle and be inserted into the reducing die body 21, ultimately affecting the forming quality of the cold-rolled steel pipe after further reducing diameter; in the above technical solution, the pressure plate 222 is generally cover-shaped, and the pressure plate 222 is detachably connected to the upper surface of the guide cover 221 by bolts, and the gap between the pressure plate 222 and the guide cover 221 forms a track to accommodate the slider 223. The middle of the plate surface of the pressure plate 222 is provided with a through hole corresponding to the position of the guide cover 221, which is large enough for the cold-rolled steel pipe to pass through; the slider 223 is located at The track between the pressure plate 222 and the guide cover 221; in this embodiment, the three-lobed slider 223 is circumferentially arranged along the edge of the through hole on the guide cover 221; the spring clamp 224 abuts against the outside of the three-lobed slider 223, so that the three-lobed slider 223 moves along the track and approaches each other; with the design of the straightening component 22, during the movement of the cold-rolled steel pipe in the guide cover 221, the slider 223 abuts against the surface of the cold-rolled steel pipe, and at the same time, it moves radially according to the diameter of the cold-rolled steel pipe, changing the distance between the three-lobed slider 223, thereby adapting to the diameter change of the cold-rolled steel pipe. The cold-rolled steel pipe is subjected to an inward radial clamping force, and always remains in the correct axial position during the movement.

[0056] The upper pressure ring 23 is connected above the guide cover 221 and located outside the guide cover 221, and is used to limit the guide cover 221 from expanding outward due to the compression of the cold-rolled steel pipe.

[0057] The lower die pull ring 24 is generally tubular in shape. The inner diameter of the lower die pull ring 24 matches the outer diameter of the upper pressure ring 23. The inner wall at the upper end and the outer wall at the lower end of the lower die pull ring 24 are respectively provided with protruding structures. The reducing die body 21, the straightening component 22, and the upper pressure ring 23 are connected inside the lower die pull ring 24, and the upper pressure ring 23 is in contact with the inner wall of the lower die pull ring 24. The lower die pull ring 24 is pressed against the upper pressure ring 23 through the protruding structure on its inner wall.

[0058] The lower mold cavity 25 has a tubular structure, and its interior is a space for accommodating the guide assembly 26 and the lower pad assembly 27. The lower end of the lower mold cavity 25 is detachably connected to the worktable of the press, and its upper end is connected to the lower mold pull ring 24. The lower mold cavity 25 and the lower mold pull ring 24 cooperate to limit the components inside the lower mold 2.

[0059] The straightening assembly 26 includes a straightening sleeve 261 and a lower die guide sleeve 262. The straightening sleeve 261 is a tubular structure, its inner diameter matching the small end diameter of the reduction through-hole on the reduction die body 21. The straightening sleeve 261 is located inside the lower die cavity 25, below the reduction die body 21, and its position corresponds to the reduction through-hole on the reduction die body 21, ensuring that the axis of the straightening sleeve 261 and the axis of the reduction through-hole are on the same straight line. After the reduction section on the cold-rolled steel pipe completes its reduction, it leaves the reduction die body 21 and further inserts into the straightening sleeve 261, continuing to move along the inner wall of the straightening sleeve 261. The straightening sleeve 261 serves to correct and straighten the pipe, preventing excessive bending of the pipe wall after reduction. The lower die guide sleeve 262 is fitted onto the outside of the straightening sleeve 261 to limit deformation of the straightening sleeve 261.

[0060] The lower pad assembly 27 is disposed inside the lower mold cavity 25. It plays a supporting role between the guide sleeve 261 and the press working platform and the lower mold cavity 25, so that the guide sleeve 261 and the lower mold guide sleeve 262 are fixed in position in the lower mold cavity 25. By filling the gap in the lower mold cavity 25 through the lower pad assembly 27, the overall stability of the lower mold 2 is improved, and its impact resistance and fatigue resistance are stronger, which can avoid damage to the guide sleeve 261 caused by stress imbalance.

[0061] In one embodiment of this application, the lower pad assembly 27 is made of 40Cr material with a hardness of 28 to 32 HRC, and includes: a first lower pad 271, a second lower pad 272, and a third lower pad 273; the first lower pad 271, the second lower pad 272, and the third lower pad 273 are all cylindrical structures, and their outer diameters match the inner diameter of the lower mold cavity 25; wherein, the first lower pad 271 is located at the bottom of the lower mold cavity 25, used to adjust the height of the guide sleeve 261 and bear the pressure transmitted by the upper component; the second lower pad 272 is placed above the first lower pad 271 and below the lower mold guide sleeve 262, the second lower... The upper surface of the pad 272 is provided with a limiting groove for engaging the guide sleeve 261. The guide sleeve 261 is fixed between the second lower pad 272 and the reducing die body 21. The second lower pad 272 restricts the position of the guide sleeve 261 in the lower die cavity 25. The middle part of the third lower pad 273 is provided with a through hole that matches the outer diameter of the guide sleeve 261. The third lower pad 273 is sleeved on the outside of the guide sleeve 261. The upper end of the third lower pad 273 abuts against the lower surface of the reducing die body 21, and its lower end abuts against the upper surface of the lower die guide sleeve 262. It cooperates with the second lower pad 272 to press and fix the lower die guide sleeve 262.

[0062] The inner diameter of the lower pressure ring 28 matches the outer diameter of the lower mold cavity 25. The inner wall of the lower pressure ring 28 is provided with a protruding structure that cooperates with the lower mold pull ring 24. The lower pressure ring 28 is sleeved on the outside of the lower mold cavity 25 and the lower mold pull ring 24, and the protruding structure on the inner wall of the lower pressure ring 28 abuts against the protruding structure on the outer wall of the lower mold pull ring 24, thereby pressing the lower mold pull ring 24 tightly above the lower mold cavity 25, so that the lower mold pull ring 24 and the lower mold cavity 25 are connected to form a whole.

[0063] As one embodiment of this application, the large end diameter of the through hole on the reducing die body 21 is 50mm, and the small end diameter is 34mm. When reducing the diameter of a cold-rolled steel pipe of different diameters, the reducing part of the cold-rolled steel pipe is inserted into the guide cover 221. The straightening component 22 holds and straightens the cold-rolled steel pipe, controls the upper die 1 to approach the lower die 2, and makes the upper end of the cold-rolled steel pipe limit and abut against the groove on the lower surface of the upper pressure head 13. The upper die 1 continues to approach the lower die 2 and presses the reducing part of the cold-rolled steel pipe into the reducing die body 21, passes through the reducing die body 21 and enters the reducing part of the guide sleeve 261 to complete the reducing. The upper die 1 moves until the upper pressure head 13 completely presses the cold-rolled steel pipe into the lower die 2. The outer diameter of the reducing part of the cold-rolled steel pipe after reducing is 24mm. The target size requirement can be achieved. The above solution optimizes the deep hole processing step on the bar in the traditional process and effectively avoids the occurrence of undesirable phenomena such as center hole eccentricity and uneven wall thickness.

[0064] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A hollow half-shaft diameter reduction mold, characterized in that, include: The upper mold is connected to an external pressurizing device, and the upper mold is provided with an upper pressure head for limiting and abutting the workpiece to be processed; The lower die is located directly below the upper die. The lower die includes a diameter reduction die body. The upper die and the lower die cooperate to press the workpiece to be processed into the diameter reduction die body for diameter reduction. The lower mold further includes a straightening component, which is located directly above the diameter reduction mold body. The straightening component is used to keep the workpiece at a fixed angle when it enters the diameter reduction mold body.

2. The hollow half-shaft diameter reduction mold according to claim 1, characterized in that, The upper mold also includes: The upper pad has a concave structure with the concave surface facing downwards; The upper pressure head cover is detachably connected to the lower part of the upper pad block, and the interior of the upper pressure head cover is provided with a space for fixing the upper pressure head.

3. The hollow half-shaft diameter reduction mold according to claim 2, characterized in that, The upper pressure head includes: A connector, which connects to the inside of the upper pressure head jacket; The abutting end face is located below the upper pressure head jacket, and the abutting end face is provided with a groove that matches the shape of the workpiece to be processed.

4. The hollow half-shaft diameter reduction mold according to claim 1, characterized in that, The reducing die body is provided with a reducing through hole, the diameter of which gradually decreases from one end face to the other end face of the reducing die body; the lower die also includes: An upper pressure ring is connected above the straightening assembly and located on the outside of the straightening assembly; The lower die pull ring has a tubular structure, and its inner diameter matches the outer diameter of the upper pressure ring. The reducing die body, the straightening component, and the upper pressure ring are connected inside the lower die pull ring. The lower die pull ring is attached to and pressed against the upper pressure ring above the upper pressure ring. The lower mold cavity is connected directly below the lower mold pull ring, and an accommodating space is provided inside the lower mold cavity; A straightening assembly is disposed within the lower mold cavity and located below the diameter reduction mold body; A lower pad assembly is disposed within the lower mold cavity to fix the position of the straightening assembly within the lower mold cavity; A lower pressure ring is sleeved on the outer side of the lower mold cavity and the lower mold pull ring, and presses the lower mold pull ring tightly above the lower mold cavity.

5. A hollow half-shaft diameter reduction mold according to claim 4, characterized in that, The straightening component includes: A guide cover, which has a cylindrical structure and a through hole, is connected above the main body of the diameter reduction die, such that the axis of the diameter reduction through hole and the through hole on the guide cover are on the same straight line. The guide cover is used to limit the outward expansion of the workpiece to be processed. A pressure plate, which is in the shape of a cover, is detachably connected to the upper surface of the guide cover, and the gap between the pressure plate and the guide cover forms a track; A slider is located within a track between the pressure plate and the guide cover; the three-lobed slider is circumferentially arranged along the edge of the through hole on the guide cover. A spring clamp abuts against the outside of the three-lobed slider, bringing the three-lobed slider closer together.

6. A hollow half-shaft diameter reduction mold according to claim 4, characterized in that, The diameter reduction die body adopts a double-layer structure of inner and outer molds, including: The inner mold has a reduced-diameter through hole located at the center of the end face of the inner mold. An outer mold is fitted over the outer side of the inner mold. The outer mold and the inner mold are joined by heat sealing. The outer mold is used to provide inward prestress to the inner mold.

7. A hollow half-shaft diameter reduction mold according to claim 4, characterized in that, The straightening component includes: A guide sleeve, which has a tubular structure, is disposed inside the lower mold cavity and located below the diameter reduction mold body. The guide sleeve is positioned corresponding to the diameter reduction through hole, so that the axis of the guide sleeve and the axis of the diameter reduction through hole are on the same straight line. The lower mold guide sleeve is sleeved on the outside of the guide sleeve to limit the deformation of the guide sleeve.

8. A hollow half-shaft diameter reduction mold according to claim 7, characterized in that, The lower pad assembly includes: The first lower pad is located at the bottom of the lower mold cavity; The second lower pad is disposed above the first lower pad and below the lower mold guide sleeve and the straight guide sleeve. The straight guide sleeve is limited and fixed between the second lower pad and the diameter reduction mold body. The third lower pad is disposed between the diameter reduction die body and the lower die guide sleeve, and cooperates with the second lower pad to press and fix the lower die guide sleeve.

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