Extrusion molding die set for spline bevel gear

Abstract

The utility model discloses a kind of extrusion forming die sets for spline bevel gear, belong to the technical field of metal punch die set, the die set includes finishing lower die, pressure upper die and follow-up core die;The upper end surface of finishing lower die has finishing die cavity, there are several tooth grooves on the lateral wall of finishing die cavity, the bottom surface middle part of finishing die cavity has a clearance hole, the diameter of clearance hole is greater than the inner diameter of spline bevel gear;Pressure upper die is vertically movably arranged directly above finishing lower die;Follow-up core die is columnar and has outer spline.The die set discards traditional multi-process cutting processing mode, simplifies manufacturing process, utilizes blank center hole metal plastic flow to directly form inner spline, reduces material cutting, material utilization is high, synchronous forming makes tooth profile precision and quality be guaranteed;The die set structure is reasonable, easy to operate, production efficiency is high, reduce production cost, can be applicable to the large-scale manufacturing of spline bevel gear.

Description

Technical Field

[0001] This utility model belongs to the technical field of metal stamping die sets, specifically relating to an extrusion forming die set for spline bevel gears. Background Technology

[0002] Splined bevel gears are gears with internal splines and external bevel tooth surfaces, widely used in automotive drive axles, transfer cases, wheel-side reducers, and transmission boxes for equipment. The manufacturing process typically involves cutting round steel, drilling holes, and broaching to create the internal splines. Finally, using the spline holes as a reference, the external bevel teeth are machined through broaching and grinding. This process is complex, produces a lot of waste, and is costly. Alternatively, some manufacturers first forge a metal billet into a toothed blank using warm forging, then drill holes and broach to create the internal splines. Finally, the bevel teeth are finished using a die. This method also suffers from high waste. Furthermore, during the finishing of the bevel teeth, it is difficult to ensure the coaxiality of the bevel teeth and the spline holes. The presence of the spline holes also makes inward deformation prone to occur during the finishing process, resulting in inconsistent forming quality. Therefore, a die set for extrusion forming is needed to improve processing efficiency, reduce costs, and ensure the positional relationship between the spline holes and the bevel teeth. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of this utility model is to provide an extrusion molding die set for spline bevel gears, which solves the technical problems of complex manufacturing and high waste in current spline bevel gear manufacturing, and achieves the effect of reducing manufacturing costs and improving molding quality.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An extrusion molding die assembly for splined bevel gears includes an integral extrusion die, comprising a finishing lower die, a pressure upper die, and a follower core die. The upper end face of the finishing lower die is recessed to form a finishing cavity. The sidewalls of the finishing cavity are circumferentially distributed with several tooth grooves that are adapted to the bevel teeth of the splined bevel gear to be formed. The bottom surface of the finishing cavity has a relief hole in the middle, the diameter of which is larger than the inner diameter of the splined bevel gear to be formed. The pressure upper die is vertically movable and positioned directly above the finishing lower die to provide downward thrust. The follower core die is columnar and has an external spline, and its diameter is adapted to the inner diameter of the splined bevel gear to be formed. In use, the follower core die is located between the finishing lower die and the pressure upper die, and its upper end face is used to abut against the lower end face of the pressure upper die.

[0005] Furthermore, the follower mandrel includes a forming section and a pre-setting section. The external spline is located on the forming section, and the diameter of the forming section is adapted to the inner diameter of the spline bevel gear to be formed. The diameter of the pre-setting section is smaller than the diameter of the forming section.

[0006] Furthermore, a guide section is provided between the forming section and the pre-setting section. The diameter of the guide section changes tapered. The large-diameter end of the guide section connects with the forming section and is matched with the diameter, while the small-diameter end connects with the pre-setting section and is matched with the diameter. The external spline on the forming section extends vertically to the transition section.

[0007] Furthermore, the free ends of the pre-set segments have chamfers.

[0008] Furthermore, the clearance hole extends vertically through the finishing lower die, and the integrated extrusion die also includes an ejector pin, which is vertically movable and positioned in the clearance hole to eject the workpiece upwards.

[0009] Furthermore, the relief hole is a stepped hole with the large diameter section above the small diameter section, the push rod is a stepped shaft with a diameter that matches the diameter of the relief hole, the length of the large diameter section of the push rod is equal to the length of the large diameter section of the relief hole, and a relief groove is provided on the upper end face of the push rod, the diameter of the relief groove being larger than the inner diameter of the spline bevel gear to be formed.

[0010] Furthermore, the integrated extrusion die also includes a ring-shaped fixed lower die, with the finishing lower die located inside the fixed lower die, and a prestressed ring provided between the finishing lower die and the fixed lower die.

[0011] Furthermore, the spline bevel gear extrusion molding die assembly also includes a demolding die, which includes a supporting lower die and an ejector upper die. The supporting lower die has a vertically penetrating demolding hole with a diameter larger than the inner diameter of the spline bevel gear to be formed. The ejector upper die is vertically movable and positioned directly above the supporting lower die, and is used to provide a downward thrust. The ejector upper die has a downwardly protruding punch with a diameter smaller than the inner diameter of the spline bevel gear to be formed.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The spline bevel gear extrusion molding die set described in this utility model provides a high-efficiency and precise overall solution for spline bevel gear extrusion molding. The main feature is the use of an integrated extrusion die. In a single pressurization process, the internal spline extrusion molding and external bevel gear finishing are completed simultaneously using a follower mandrel. This fundamentally eliminates the traditional cutting process, resulting in higher material utilization, significantly reduced waste, and perfect guarantee of the coaxiality and dimensional accuracy of the internal and external tooth profiles. In addition, the internal follower mandrel support during the extrusion process effectively avoids thin-wall deformation, ensuring the accuracy and quality of the tooth profile.

[0013] 2. The spline bevel gear extrusion molding die set of this utility model separates extrusion molding and core mold ejection into two independent steps. A dedicated demolding die is responsible for ejecting the follower core mold. This avoids completing complex actions on a single die set, greatly shortens the cycle time of the main extrusion die, improves equipment utilization and production cycle, and reduces die wear, which is beneficial for protecting the precision-formed tooth surface. The die set has a reasonable structure, is easy to operate, has high production efficiency, and significantly reduces production costs. It is particularly suitable for the large-scale manufacturing of spline bevel gears. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the integrated extrusion die described in the embodiment; Figure 2 This is a schematic diagram of the demolding mold described in the embodiment; Figure 3 This is a schematic diagram of the structure of the first blank in the embodiment; Figure 4 This is a schematic diagram of the structure corresponding to step 3) in the embodiment; Figure 5 This is a schematic diagram of the structure corresponding to step 4) in the embodiment; Figure 6 This is a schematic diagram of the structure corresponding to step 7) in the embodiment; Figure 7 This is a schematic diagram of the structure of the spline bevel gear to be formed as described in the embodiment; Among them, the finishing lower mold 1, the pressure upper mold 2, the follower core mold 3, the finishing mold cavity 4, the tooth groove 5, the forming section 6, the pre-positioned section 7, the guide section 8, the chamfer 9, the ejector pin 10, the relief groove 11, the fixed lower mold 12, the prestress ring 13, the supporting lower mold 14, the ejector upper mold 15, the demolding hole 16, the punch 17, the first blank 18, the central groove 19, the second blank 20, the central hole 21, the conical tooth 22, and the internal spline 23. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0016] Example: Please see Figure 1 and Figure 7An extrusion molding die assembly for spline bevel gears includes an integral extrusion die, comprising a finishing lower die 1, a pressure upper die 2, and a follower core die 3. The upper end face of the finishing lower die 1 is recessed to form a finishing cavity 4. The side wall of the finishing cavity 4 is circumferentially distributed with several tooth grooves 5, which are adapted to the bevel teeth 22 of the spline bevel gear to be formed. The bottom surface of the finishing cavity 4 has a relief hole in the middle, the diameter of which is larger than the inner diameter of the spline bevel gear to be formed. The pressure upper die 2 is vertically movable and positioned directly above the finishing lower die 1 to provide downward thrust. The follower core die 3 is columnar and has an external spline, and its diameter is adapted to the inner diameter of the spline bevel gear to be formed. In use, the follower core die 3 is located between the finishing lower die 1 and the pressure upper die 2, and its upper end face is used to abut against the lower end face of the pressure upper die 2.

[0017] The spline bevel gear extrusion molding die set of this utility model has an integrated extrusion die as its core, which consists of a finishing lower die 1, a pressure upper die 2, and a follower core die 3 working together. In use, a first blank 18 with bevel teeth on the outside and central grooves 19 on both ends is first prepared by warm forging, and then a through central hole 21 is formed by punching to obtain a second blank 20. Subsequently, the integrated extrusion die is used for processing: the second blank 20 is placed in the cavity of the finishing lower die 1, and the follower core die 3 is pre-positioned above its central hole 21; the pressure upper die 2 is pressed down, pushing the follower core die 3 into the central hole 21, and simultaneously achieving the finishing of the inner spline 23 and the outer bevel teeth 22 in the hole wall; after forming, the workpiece is taken out, and in the subsequent process, the follower core die 3 is taken out from the central hole 21, finally obtaining a complete spline bevel gear product.

[0018] The splined bevel gear extrusion molding die assembly of this utility model achieves simultaneous extrusion molding of the internal spline 23 and finishing of the external bevel gear 22 in a single pressurization process by pressing the follower mandrel 3 into the second blank 20 with a center hole 21. This design eliminates the complex multi-step process of drilling holes, broaching the spline, and then machining the tooth profile based on the spline in the traditional process, greatly simplifying the manufacturing steps. It not only improves the processing efficiency and reduces material waste, but also avoids the multiple positioning errors caused by broaching the spline first and then machining the tooth profile in the traditional process. The design significantly improves the coaxiality of the internal spline 23 and the bevel gear 22. Simultaneously, the follower mold 3 provides support to the inner hole of the blank during extrusion molding, preventing inward deformation of the bevel gear 22 during finishing and ensuring tooth integrity and dimensional stability. Furthermore, the clearance hole design provides downward space for the follower mold 3, which can be modularly replaced, enhancing the mold's versatility and adaptability. Therefore, this invention effectively solves the current problems of complex spline bevel gear manufacturing and high waste, and is beneficial for reducing manufacturing costs and improving molding quality.

[0019] Please see Figure 1The follower mandrel 3 includes a forming section 6 and a pre-positioning section 7. The external spline is located on the forming section 6. The diameter of the forming section 6 is adapted to the inner diameter of the spline bevel gear to be formed. The diameter of the pre-positioning section 7 is smaller than the diameter of the forming section 6. In this way, the follower mandrel 3 is designed in segments. The forming section 6 is used to extrude and form the internal spline 23. The diameter of the pre-positioning section 7 is slightly smaller. It can be pre-inserted into the center hole 21 of the blank before extrusion, which plays a preliminary positioning and guiding role, ensuring that the mandrel and the blank are aligned during the pressing process, and avoiding spline misalignment or uneven tooth profile caused by off-center loading.

[0020] Please see Figure 1 A guide section 8 is provided between the forming section 6 and the pre-setting section 7. The diameter of the guide section 8 is tapered. The large diameter end of the guide section 8 connects with the forming section 6 and is compatible with the diameter, while the small diameter end connects with the pre-setting section 7 and is compatible with the diameter. The external spline on the forming section 6 extends vertically to the transition section. In this way, the tapered guide section 8 is provided between the forming section 6 and the pre-setting section 7, and the external spline extends to this section. It can guide the mandrel to smoothly enter the center hole 21 in the initial pressing stage, gradually expand the contact area, smoothly transition to full tooth extrusion, reduce impact load, and help improve the spline forming quality and mold life.

[0021] Please see Figure 1 The free end of the pre-positioned section 7 has a chamfer 9; thus, the chamfer 9 at the end of the pre-positioned section 7 makes it easier for manual or robotic arms to quickly and accurately insert it into the center hole 21 of the blank, improving assembly efficiency, reducing pre-positioning difficulty, and making the spline bevel gear extrusion molding die set more suitable for automated production lines.

[0022] Please see Figure 1 The clearance hole extends vertically through the finishing lower die 1. The integrated extrusion die also includes an ejector pin 10, which is vertically movable and installed in the clearance hole to eject the workpiece upwards. In this way, the clearance hole through-hole design and the matching ejector pin 10 can quickly eject the workpiece out of the finishing die cavity 4 after molding, avoiding workpiece damage or die scratching caused by manual prying, and improving production rhythm and operational safety.

[0023] Please see Figure 1 The relief hole is a stepped hole with the larger diameter section above the smaller diameter section. The ejector rod 10 is a stepped shaft with a diameter that matches the diameter of the relief hole. The length of the larger diameter section of the ejector rod 10 is equal to the length of the larger diameter section of the relief hole. A relief groove 11 is provided on the upper end face of the ejector rod 10. The diameter of the relief groove 11 is larger than the inner diameter of the spline bevel gear to be formed. In this way, the ejector rod 10 adopts a stepped shaft structure and cooperates with the stepped relief hole. During extrusion, the stepped surface of the ejector rod 10 contacts the mold base, providing reverse support force for the blank, enhancing extrusion stability, and preventing the blank from moving down too much, resulting in insufficient tooth filling. The relief groove 11 at the upper end of the ejector rod 10 provides a receiving space for the lower end of the follower core mold 3, avoiding structural interference and ensuring the integrity of the extrusion stroke.

[0024] Please see Figure 1 The integrated extrusion die also includes a ring-shaped fixed lower die 12, with the finishing lower die 1 located inside the fixed lower die 12, and a prestressed ring 13 provided between the finishing lower die 1 and the fixed lower die 12; in this way, the finishing lower die 1 is assembled into the fixed lower die 12 through the prestressed ring 13, which can enhance the rigidity of the die cavity during the high-pressure extrusion process, reduce elastic deformation, and ensure the accuracy of the tooth profile; at the same time, the modular design facilitates the quick replacement of the finishing lower die 1, adapts to the production of gears of different specifications, reduces changeover time, and improves the flexibility of the production line.

[0025] Please see Figure 2 The spline bevel gear extrusion molding die set also includes a demolding die, which includes a supporting lower die 14 and an ejector upper die 15. The supporting lower die 14 has a vertically penetrating demolding hole 16, the diameter of which is larger than the inner diameter of the spline bevel gear to be formed. The ejector upper die 15 is vertically movable and positioned directly above the supporting lower die 14, and is used to provide downward thrust. The ejector upper die 15 has a downwardly protruding punch 17, the diameter of which is smaller than the inner diameter of the spline bevel gear to be formed. In this way, the independently set demolding die is specifically used to eject the follower core mold 3 from the formed gear, separating it from the extrusion process, avoiding complex demolding operations on an integrated die, shortening the extrusion die occupation time, and improving overall production efficiency. The diameter of the punch 17 is smaller than the inner diameter of the gear, so it can accurately apply force to the follower core mold 3 rather than the gear body, protecting the formed tooth surface and spline structure from damage.

[0026] To facilitate a better understanding of the extrusion molding die assembly for splined bevel gears described in this utility model, its working principle is briefly introduced as follows: 1) Preparation of precast blanks: First, the metal material is formed into the first blank 18 through a warm forging process, such as... Figure 3 As shown, the blank has aligned central grooves 19 on both ends, and the outer surface has been initially formed with a tapered tooth profile, laying the foundation for subsequent finishing. 2) Trimming and punching: Trim the edges of the first blank 18 to remove the burrs, and punch the grooves at both ends to form a central through hole to obtain the second blank 20; this step is used to standardize the blank size and provide pre-machined holes for the extrusion of the internal spline 23. 3) Blank positioning and mold assembly: Place the second blank 20 into the finishing mold cavity 4 of the finishing lower mold 1, ensuring that its conical teeth 22 initially engage with the mold cavity tooth grooves 5 to achieve radial positioning, such as... Figure 4 As shown; 4) Pre-setting the follower core mold 3: Insert the pre-set section 7 of the follower core mold 3 downwards into the center hole 21 of the second blank 20. The diameter of the pre-set section 7 is clearance-fitted with the center hole 21 to achieve preliminary centering and ensure accurate relative position between the core mold and the blank before extrusion. Figure 5 As shown; 5) Synchronous extrusion molding: The pressure upper die 2 moves downward, applying axial pressure and pushing the follower core die 3 to move downward as a whole. The forming section 6 of the follower core die 3 is extruded into the central hole 21, causing the metal on the hole wall to plastically flow and fill the space of the spline tooth groove 5, thereby precisely forming the inner spline 23. At the same time, under the action of pressure, the blank moves downward as a whole, and its outer conical teeth 22 are further extruded with the tooth groove 5 of the finishing die cavity 4 to complete the finishing and calibration of the tooth surface. During this process, the internal follower core die 3 provides rigid support for the blank, effectively preventing the teeth from collapsing and deforming inward, and ensuring the coaxiality and dimensional accuracy of the inner spline 23 and the outer conical teeth 22. 6) Ejection and demolding of workpiece: After extrusion, the upper pressure die 2 returns upward; the ejector rod 10 moves upward and smoothly ejects the formed workpiece from the finishing die cavity 4 through the clearance hole of the finishing lower die 1, so that it is separated from the finishing lower die 1. 7) Transfer and Inverted Positioning: Transfer the formed gear workpiece with the follower core mold 3 to the demolding station and invert it onto the supporting lower mold 14, aligning the follower core mold 3 with the demolding hole 16. Figure 6 As shown; 8) Ejecting the follower core mold 3: The ejector upper mold 15 moves downward, and its punch 17 presses into the spline 23 hole of the gear, directly acting on the upper end of the follower core mold 3, pushing it downward until it completely disengages from the gear inner hole and falls into and passes through the demolding hole 16 of the supporting lower mold 14. 9) Removing the final part: As the upper die 15 returns, the punch 17 retracts. At this point, the follower core die 3 has been removed, and the final splined bevel gear can be removed from the supporting lower die 14. The entire manufacturing process is complete, and the splined bevel gear is as follows: Figure 7 As shown; When in use, three follower core molds of the same specifications can be prepared. Two are used to alternate between the integrated extrusion mold and the demolding mold to ensure the continuity of extrusion molding and demolding, thereby improving the processing effect. The other one is reserved.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of this utility model that do not depart from the spirit and scope of this technical solution should be covered within the scope of the claims of this utility model.

Claims

1. An extrusion molding die set for splined bevel gears, characterized in that: The device includes an integrated extrusion die, comprising a finishing lower die, a pressure upper die, and a follower core die. The upper end face of the finishing lower die is recessed to form a finishing cavity. The side wall of the finishing cavity has several circumferentially distributed tooth grooves that are adapted to the bevel teeth of the spline bevel gear to be formed. The bottom surface of the finishing cavity has a relief hole in the middle, the diameter of which is larger than the inner diameter of the spline bevel gear to be formed. The pressure upper die is vertically movable and positioned directly above the finishing lower die to provide downward thrust. The follower core die is columnar and has an external spline, and its diameter is adapted to the inner diameter of the spline bevel gear to be formed. In use, the follower core die is located between the finishing lower die and the pressure upper die, and its upper end face is used to abut against the lower end face of the pressure upper die.

2. The extrusion molding die set for splined bevel gears according to claim 1, characterized in that: The follower mandrel includes a forming section and a pre-setting section. The external spline is located on the forming section. The diameter of the forming section is adapted to the inner diameter of the spline bevel gear to be formed. The diameter of the pre-setting section is smaller than the diameter of the forming section.

3. The extrusion molding die set for splined bevel gears according to claim 2, characterized in that: A guide section is provided between the forming section and the pre-setting section. The diameter of the guide section changes tapered. The large diameter end of the guide section connects with the forming section and is compatible with the diameter, while the small diameter end connects with the pre-setting section and is compatible with the diameter. The external spline on the forming section extends vertically to the transition section.

4. The extrusion molding die set for splined bevel gears according to claim 3, characterized in that: The free end of the preset segment has a chamfer.

5. The extrusion molding die set for splined bevel gears according to claim 1, characterized in that: The clearance hole extends vertically through the finishing lower die. The integrated extrusion die also includes an ejector pin, which is vertically movable and positioned in the clearance hole to eject the workpiece upwards.

6. The extrusion molding die set for splined bevel gears according to claim 5, characterized in that: The relief hole is a stepped hole with the large diameter section above the small diameter section. The push rod is a stepped shaft with a diameter that matches the diameter of the relief hole. The length of the large diameter section of the push rod is equal to the length of the large diameter section of the relief hole. A relief groove is provided on the upper end face of the push rod, and the diameter of the relief groove is larger than the inner diameter of the spline bevel gear to be formed.

7. The extrusion molding die set for splined bevel gears according to claim 1, characterized in that: The integrated extrusion die also includes a ring-shaped fixed lower die, with the finishing lower die located inside the fixed lower die, and a prestressed ring provided between the finishing lower die and the fixed lower die.

8. The extrusion molding die set for splined bevel gears according to claim 1, characterized in that: The spline bevel gear extrusion molding die set also includes a demolding die, which includes a supporting lower die and an ejector upper die. The supporting lower die has a vertically penetrating demolding hole with a diameter larger than the inner diameter of the spline bevel gear to be formed. The ejector upper die is vertically movable and positioned directly above the supporting lower die, and is used to provide downward thrust. The ejector upper die has a downwardly protruding punch with a diameter smaller than the inner diameter of the spline bevel gear to be formed.

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