Rotary swaging die for hollow pipes

Abstract

The utility model discloses a hollow pipe rotary swaging die which comprises a supporting table located on the lower portion and a workpiece forging placing table located on the upper portion and used for placing the outer contour of a hollow pipe. The upper portion of an inner bent face of the front end face of the supporting table extends upwards and outwards to form an extension section for increasing the forgeable length of the supporting table, the lower portion of the inner bent face of the front end face of the supporting table extends downwards and outwards and is vertically bent to form an assembly connector section, and the joint of the extension section and the assembly connector section is in smooth transition through a tangent arc section. Left and right symmetrical concave surfaces are arranged at the top of the workpiece forging placement table, each concave surface comprises a cambered surface precision forging forming area arranged in the middle and a plane pre-forging shrinkage area extending outwards along the left edge and the right edge of the cambered surface precision forging forming area, and the plane pre-forging shrinkage areas are tangent to the left edge and the right edge of the cambered surface precision forging forming area; therefore, the hollow pipe with the forged diameter reduced can fall into the cambered surface precision forging forming area from the plane pre-forging shrinkage area, and the rotary forging method has the advantages that the rotary forging difficulty is greatly reduced, the fracture resistance of the die is high, the metal fluidity is improved, and the product precision is high.

Description

Technical Field

[0001] The utility model belongs to the technical field of hollow tube rotary forging, and in particular relates to a hollow tube rotary forging die. Background Art

[0002] Rotary forging (rotary forging) is a process method used for precision forming of parts such as pipes and bars. The forging hammers are evenly distributed around the parts to be processed along the circumference. While rotating around the parts, the forging hammers perform high-frequency, short-stroke forging movements in the radial direction, causing the parts to be processed to accumulate from small deformation to larger deformation.

[0003] The automotive industry currently widely uses rotary forging technology in steering columns and transmission systems. Due to the improvement of part performance by rotary forging and the diversity of applications of precision rotary forging technology, many processes that were originally unable to be processed by ordinary rotary forging machines have been solved. Parts that were originally used for solid bars can now be widely replaced by tube parts.

[0004] The hollow half-axle belonging to the hollow tube type is also called the drive shaft. It is the shaft that transmits torque between the gearbox reducer and the drive wheel. It has the characteristics of high speed and high torque. The hollow half-axle products produced by rotary forging technology can achieve 100% hollowness and more than 85% material utilization. However, the hollow shaft often has a blank tube length of 400mm to 700mm, an outer diameter of 30mm to 40mm, and a wall thickness of 5mm to 8mm. The existing rotary forging die support table is short and cannot contact the end area of ​​the longer hollow tube workpiece, resulting in great difficulty in rotary forging. In addition, the metal fluidity is poor during forging, and fish scales and wrinkles are easily formed during the forging process, which will greatly affect product performance and production efficiency. Utility Model Content

[0005] The utility model aims to provide a hollow tube rotary forging die, which has low rotary forging difficulty and strong forging metal fluidity, and solves the problems that the current rotary forging die support table is short and cannot contact the end of a longer hollow tube workpiece, resulting in great difficulty in rotary forging, and the poor metal fluidity during forging leads to fish scale patterns and wrinkles in the forging process.

[0006] To this end, the technical solution adopted by the utility model is: a hollow tube rotary forging die, comprising a support platform located at the bottom and a workpiece forging placement platform located at the top for placing the outer contour of the hollow tube, the front and rear end faces of the support platform are provided with asymmetric inner bending surfaces, the upper part of the inner bending surface of the front end face of the support platform extends upward and outward to form an extension section for increasing the forging length of the support platform, the lower part extends downward and outward and is vertically bent to form an assembly interface section, the intersection of the extension section and the assembly interface section is smoothly transitioned through a tangent arc section, the top of the workpiece forging placement platform is provided with a left-right symmetrical concave surface, the concave surface includes a centrally arranged arc surface precision forging forming area and a plane pre-forging shrinkage area extending outward along the left and right edges of the arc surface precision forging forming area, the plane pre-forging shrinkage area is tangent to the left and right edges of the arc surface precision forging forming area, so that the hollow tube after the diameter is reduced by forging can fall from the plane pre-forging shrinkage area into the arc surface precision forging forming area.

[0007] As a preferred embodiment of the above scheme, the horizontal length of the extension section is 3.5mm~23.8mm, and the angle with the horizontal direction is 10°~30°. The size is reasonable. By adjusting the horizontal length of the extension section and the angle with the horizontal direction, the mold can be ensured to meet the forging surface length while avoiding interference between the mold and the equipment.

[0008] It is further preferred that the angle between the inclined surface of the assembly interface section and the horizontal direction is 60° to 90°, and the diameter of the arc section is 2mm to 4mm. The angle between the extension section and the horizontal direction can be reduced by adjusting the diameter of the arc section. During normal forging, the arc end structure can effectively enhance the strength of the mold and prevent breakage caused by excessive forging force.

[0009] It is further preferred that the angle of the plane pre-forging shrinkage zone is 130° to 150°, which is a reasonable angle. The diameter of the arc surface precision forging forming zone is 4mm to 8mm larger than the diameter of the hollow tube before forging. By setting a 4-8mm margin, the starting diameter and the final diameter of the arc surface precision forging forming zone can be adjusted to avoid excessive diameter margin of the arc surface precision forging forming zone, which increases the forging difficulty during forging.

[0010] More preferably, the workpiece forging placement table is in a horizontally extended state in the middle, and the front and rear ends are bent downward in an inclined state, and the structure is reasonable.

[0011] Beneficial effects of the utility model:

[0012] (1) Compared with the current rotary forging die support table, which is short and cannot contact the end of a longer hollow tube workpiece, this solution uses the upper part of the inner bending surface of the front end surface of the support table to extend upward and outward to form an extension section, which lengthens the forging length of the die, allowing the die support table to contact the end of the hollow tube, greatly reducing the difficulty of rotary forging. Then, the arc section tangent to the extension section and the assembly interface section ensures the anti-fracture ability of the die under high forging force working conditions. The assembly interface section ensures the die assembly effect. The asymmetric inner bending surfaces of the front and rear end surfaces of the support table can meet the interface requirements of the precision forging equipment and the forging requirements of the hollow tube. The conception is ingenious and the structural design is reasonable.

[0013] (2) Compared with the poor metal fluidity during current forging, this solution adopts an arc surface precision forging forming area and a plane pre-forging shrinkage area tangent to the left and right edges of the arc surface precision forging forming area. During the forging process, the plane pre-forging shrinkage area in the forging surface first contacts the metal surface of the hollow tube semi-axle blank, and the arc surface precision forging forming area does not participate in the forging. At this time, it is actually a line contact between the plane pre-forging shrinkage area and the arc surface of the blank tube, which minimizes the contact area during the rotary forging process. Under the same forging force and forging speed, that is, the deformation amount of the metal per forging, it can effectively reduce the difficulty of metal flow and improve metal fluidity. Then, after the hollow tube with a reduced diameter after forging falls from the plane pre-forging shrinkage area into the arc surface precision forging forming area, the arc surface precision forging forming area is used to realize the precision forming of the raw materials, thereby improving the product precision. The structure is linked together, the process flow is simple, and the operation is convenient and fast.

[0014] In summary, it has the advantages of greatly reducing the difficulty of rotary forging, strong resistance to mold fracture, improved metal fluidity, and high product precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the utility model.

[0016] Figure 2 for Figure 1 Side view of.

[0017] Figure 3 Schematic diagram of hollow tubes placed on a rotary forging die. DETAILED DESCRIPTION

[0018] The present invention will be further described below by way of embodiments and in conjunction with the accompanying drawings:

[0019] Combination Figure 1 — Figure 3 As shown, a hollow tube rotary forging die is composed of a support platform 1 located at the bottom and a workpiece forging placement platform 2 located at the top for placing the outer contour of the hollow tube 3.

[0020] The front and rear end surfaces of the support platform 1 are provided with asymmetric inner bending surfaces.

[0021] The upper part of the inner bending surface of the front end surface of the support platform 1 extends upward and outward to form an extension section 11 that increases the forging length of the support platform 1, and the lower part extends downward and outward and is vertically bent to form an assembly interface section 12.

[0022] The junction between the extension section 11 and the assembly interface section 12 is smoothly transitioned through a tangent arc section 13 .

[0023] The horizontal length of the extension section 11 is preferably 3.5 mm to 23.8 mm, and the angle between the extension section 11 and the horizontal direction is 10° to 30°.

[0024] The angle between the inclined surface of the assembly interface section 12 and the horizontal direction is preferably 60° to 90°.

[0025] The diameter of the arc segment 13 is preferably 2 mm to 4 mm.

[0026] The top of the workpiece forging placement table 2 is provided with a bilaterally symmetrical concave surface.

[0027] The workpiece forging placement table 2 is in a horizontally extending state in the middle, and the front and rear ends are bent downward and in an inclined state.

[0028] The concave surface is composed of a centrally arranged arc surface precision forging forming area 21 and a plane pre-forging shrinkage area 22 extending outward along the left and right edges of the arc surface precision forging forming area 21 .

[0029] The diameter of the arc surface precision forging forming area 21 is preferably 4 mm to 8 mm larger than the diameter of the hollow tube 3 before forging.

[0030] The included angle of the planar pre-forging contraction zone 22 is preferably 130° to 150°.

[0031] The plane pre-forging shrinkage zone 22 is tangent to the left and right edges of the cambered surface precision forging forming zone 21 , so that the hollow tube 3 with a reduced diameter after forging can fall from the plane pre-forging shrinkage zone 22 into the cambered surface precision forging forming zone 21 .

[0032] Hollow tube type 3 uses a forging area with an outer diameter of φ29mm and a raw material area with an outer diameter of φ34.

[0033] Four rotary forging dies are evenly distributed and fixedly installed in the groove of the rotary forging machine along the circumferential direction. The final structural dimension of the product is designed to be φ29mm. According to the volume release value set in the arc surface precision forging forming area 21, the arc surface diameter is φ35mm. According to the structural dimension of the product, the outer diameter of the raw material blank tube is selected as φ37mm. During the feeding process of the rotary forging die, when the forging arc value formed by the forging surface of the rotary forging die is reduced to φ37mm, the forging surface of the rotary forging die begins to contact with the plane pre-forging shrinkage area 22, that is, the plane pre-forging shrinkage area 22 contacts the blank tube line to implement forging, thereby accelerating the flow of metal. When the diameter of the forging surface of the rotary forging die is reduced to Φ35mm, the arc surface precision forging forming area 21 begins to contact with the workpiece, and forging is implemented under the action of the arc surface until it is reduced to the final outer circle size of the left end of the product of φ29mm.

[0034] The rotary forging die adopts the above structural design, which can complete the rotary forging process of larger diameter and thicker wall blank tubes, reduce the equipment vibration value to below 25, and improve the external forging accuracy to H7 level, which solves the problems of wrinkles and cracks that are easy to appear in the forging process of hollow shafts or tubes. It is not only suitable for the design of rotary forging dies for hollow semi-axle products in automobiles, but also can be used for the design of rotary forging dies for hollow tube rotary forging products with a diameter of 20-36mm and a wall thickness of 4-10mm.

[0035] If the flat pre-forging shrinkage area 22 and the arc-surface finishing forging forming area 21 fail to achieve a smooth transition during the manufacturing process of the rotary forging die, it is necessary to use rubber grinding wheel polishing to repair it, which can improve the fluidity of the material and solve the problem of difficult or abnormal material flow caused by the die in the process from the pre-forging area to the finishing forging area, thereby improving the dimensional accuracy and surface roughness of the parts after forging.

Claims

1. A hollow tube rotary forging die, comprising a support platform (1) at the bottom and a workpiece forging placement platform (2) at the top for placing the outer contour of the hollow tube (3), characterized in that: The front and rear end surfaces of the support platform (1) are provided with asymmetric inner bending surfaces. The upper part of the inner bending surface of the front end surface of the support platform (1) extends upward and outward to form an extension section (11) that increases the forging length of the support platform (1), and the lower part extends downward and outward and is vertically bent to form an assembly interface section (12). The intersection of the extension section (11) and the assembly interface section (12) is smoothly transitioned through a tangent arc section (13). The top of the workpiece forging placement platform (2) is provided with a left-right symmetrical concave surface, which includes a centrally arranged arc surface precision forging forming area (21) and a plane pre-forging shrinkage area (22) extending outward along the left and right edges of the arc surface precision forging forming area (21). The plane pre-forging shrinkage area (22) is tangent to the left and right edges of the arc surface precision forging forming area (21), so that the hollow tube (3) with a reduced diameter after forging can fall from the plane pre-forging shrinkage area (22) into the arc surface precision forging forming area (21).

2. The hollow tube rotary forging die according to claim 1, characterized in that: The horizontal length of the extension section (11) is 3.5 mm to 23.8 mm, and the angle between the extension section (11) and the horizontal direction is 10° to 30°.

3. The hollow tube rotary forging die according to claim 1, characterized in that: The angle between the inclined surface of the assembly interface section (12) and the horizontal direction is 60° to 90°, and the diameter of the circular arc section (13) is 2 mm to 4 mm.

4. The hollow tube rotary forging die according to claim 1, characterized in that: The included angle of the plane pre-forging shrinkage zone (22) is 130° to 150°, and the diameter of the arc surface precision forging forming zone (21) is 4mm to 8mm larger than the diameter of the hollow tube (3) before forging.

5. The hollow tube rotary forging die according to claim 1, characterized in that: The workpiece forging placement platform (2) is in a horizontally extended state in the middle, and the front and rear ends are bent downwards in an inclined state.

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