Backward extrusion pipe production die

Abstract

The utility model relates to a backward extrusion pipe production die which comprises an upper die sleeve, a punch, a lower die and an ejector, and the inner wall of the upper die sleeve is matched with the outer wall of the lower die in a nested mode. The difference between the outer diameter of the lower die and the inner diameter of the upper die sleeve is a die assembly gap; the end face of the inner wall of the upper die sleeve and the end face of the top of the lower die form a closed die cavity during die assembly, and the punch is fixed to the middle of the upper die sleeve, extends in the axial direction and is used for applying reverse extrusion pressure to a blank. The ejector is arranged at the bottom of the lower die and used for ejecting the formed backward extrusion pipe. According to the scheme, accurate matching is formed between the inner wall of the upper die sleeve and the outer wall of the lower die, it is ensured that the upper die and the lower die are always kept on the same axis in the die assembly process, and the centering die assembly mechanism is designed, so that die alignment deviation is avoided, die abrasion is reduced, wall thickness consistency and size stability of products are ensured, and the production efficiency is improved. And the production precision is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of aluminum alloy forging, specifically to a reverse extrusion tube production mold. Background Technology

[0002] With the increasing demand for miniaturized and lightweight metal components in the industrial sector, thin-walled, small-diameter, and long ring forgings (such as tubes with an outer diameter < 800 mm, wall thickness < 60 mm, and length > 1000 mm) are gradually becoming a core requirement in the manufacturing industry. Traditionally, these products are mainly produced through hole expansion forming or ring rolling processes, but significant technical bottlenecks exist.

[0003] 1. Hole expansion forming requires a forging allowance of at least 35mm on one side of the billet, with a material feeding ratio of over 2.2, resulting in extremely low material utilization. In addition, the billet forming process requires an additional punching process, leading to low production efficiency.

[0004] 2. Although the ring rolling process can reduce the allowance to 12mm on one side (feed ratio of about 1.5), it still requires complex rolling equipment and has insufficient control over the dimensional stability of thin-walled tubes, which can easily lead to eccentricity or uneven wall thickness.

[0005] 3. In the existing mold structure, the upper and lower molds have insufficient closing accuracy and poor centering, which can easily lead to product coaxiality deviation and make demolding difficult, further affecting the finished product qualification rate.

[0006] To overcome the aforementioned limitations, the industry has developed a reverse extrusion forming process. This process involves directly placing preformed bars into the mold cavity, where a punch applies reverse extrusion force to shape the metal. This process can reduce the forging allowance to 7–10 mm per side (only 4–5 mm is needed on high-precision die forging presses), optimize the material feeding ratio to 1.3, and eliminate the punching process, significantly improving material utilization and production efficiency.

[0007] However, in the existing reverse extrusion process, the mold guidance and positioning mostly rely on simple cylindrical surface mating. When the mold is closed, misalignment can easily lead to mold wear or large deviations in product wall thickness. Utility Model Content

[0008] This utility model provides a reverse extrusion tube production mold, the purpose of which is to solve the problem in the prior art that mold wear or large deviation in product wall thickness is easily caused by misalignment during mold closing.

[0009] To achieve the above objectives, this utility model provides a reverse extrusion tube production mold, including an upper mold sleeve, a punch, a lower mold, and an ejector;

[0010] The inner wall of the upper mold sleeve and the outer wall of the lower mold form a nested fit; the difference between the outer diameter of the lower mold and the inner diameter of the upper mold sleeve is the mold closing clearance;

[0011] The inner wall end face of the upper die sleeve and the top end face of the lower die form a closed mold cavity when the mold is closed. The punch is fixed in the middle of the upper die sleeve and extends axially to apply a counter-extrusion force to the blank.

[0012] The ejector is located at the bottom of the lower mold and is used to eject the formed reverse extrusion tube.

[0013] Furthermore, the mold closing gap is 0.2±0.1mm.

[0014] Furthermore, the upper mold sleeve has an annular structure with a tapered guide surface on its inner wall, and the outer edge of the lower mold sleeve is provided with a tapered guide section that matches the tapered guide surface on the inner wall of the upper mold sleeve.

[0015] Furthermore, the taper angle of the tapered guide surface and the tapered guide segment is 1° to 50°.

[0016] Furthermore, the inner cavity of the lower mold is cylindrical, matching the outer diameter of the reverse extrusion tube.

[0017] Furthermore, the ejector is coaxial with the inner cavity of the lower mold.

[0018] Furthermore, the lower mold has a tapered inner cavity, and the ejector includes a top block, the outer wall of which is tapered and adapted to the inner cavity of the lower mold.

[0019] Furthermore, the punch includes a rod and a working end connected coaxially. One end of the rod is connected to the upper die sleeve, and the other end is connected to the working end. The outer wall of the working end is a transition slope, which is a conical structure with its outer diameter gradually increasing from the rod to the bottom surface of the working end.

[0020] Furthermore, the gap between the guide section and the inner wall of the lower die is greater than the thickness of the reverse extrusion tube.

[0021] Furthermore, the mold is made of alloy steel.

[0022] The beneficial effects of this utility model are:

[0023] Compared with existing technologies, the reverse extrusion tube production mold provided by this utility model effectively solves the problem of mold wear or large product wall thickness deviation caused by misalignment during mold closing by adopting a nested fit design between the upper mold sleeve and the outer wall of the lower mold. This ensures that the industry has been unable to produce high-precision reverse extrusion tubes. Specifically, the inner wall of the upper mold sleeve and the outer wall of the lower mold form a precise fit, ensuring that the upper and lower molds remain on the same axis during the mold closing process. This avoids mold misalignment, reduces mold wear, and guarantees the consistency of product wall thickness and dimensional stability, thereby effectively improving production accuracy and mold lifespan. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0025] Figure 1 This is a structural diagram of a reverse extrusion tube production mold disclosed in an embodiment of this utility model.

[0026] Figure 2 This is a schematic diagram of a reverse extrusion structure after mold closing, as disclosed in an embodiment of this utility model.

[0027] Figure 3 This is a schematic diagram of a reverse extrusion molding structure disclosed in an embodiment of this utility model.

[0028] Figure 4 This is a schematic diagram of a material discharge structure disclosed in an embodiment of this utility model.

[0029] Reference numerals: 1. Upper die sleeve; 2. Punch; 3. Lower die; 4. Ejector; 5. Blank; 2a. Rod; 2b. Working end; 2c. Transition slope; 10. Conical guide surface; 20. Gap; 30. Conical guide section; 31. Inner cavity; 40. Ejector block. Detailed Implementation

[0030] The following detailed description of the reverse extrusion tube production mold of this utility model is provided in conjunction with the accompanying drawings. This embodiment is only used to explain this utility model and does not constitute a limitation.

[0031] like Figure 1 As shown, the reverse extrusion tube production mold in this embodiment includes an upper die sleeve 1, a punch 2, a lower die 3, and an ejector 4. The specific structure and cooperation relationship of each component are as follows:

[0032] The upper die sleeve 1 is a ring-shaped forged steel component. Its inner wall forms a tight nested fit with the outer wall of the lower die 3, ensuring the coaxiality of the upper die sleeve 1 and the lower die 3 when the mold is closed, and ensuring that the punch 2 is in the center position in the mold cavity. The inner wall end face of the upper die sleeve 1 and the top end face of the lower die 3 form a closed mold cavity when the mold is closed, providing a stable spatial environment for reverse extrusion molding.

[0033] like Figure 2 As shown, the punch 2 is fixed to the middle of the upper die sleeve 1 and extends axially in the direction of extrusion. Its function is to apply a counter-extrusion force to the blank 5, causing the blank 5 to be extruded and deformed within the die, thereby producing a counter-extruded tube. In practical applications, the material and surface treatment of the punch are selected according to different production requirements.

[0034] The lower die 3 is the bottom part of the die for producing the reverse extrusion tube. Its outer wall and the inner wall of the upper die sleeve 1 form a nested fit to ensure that the upper and lower dies are coaxial when the die is closed. The difference between the outer diameter of the lower die 3 and the inner diameter of the upper die sleeve 1 is the die closing clearance.

[0035] Ejector 4 is installed at the bottom of the lower die 3 and serves to eject the formed reverse extrusion tube. The driving and adjustment methods of ejector 4 can be adjusted appropriately according to the needs of different production batches.

[0036] When using this reverse extrusion tube production mold, the blank 5 is first placed in the lower mold 3. When the mold closes, the upper mold sleeve 1 fits tightly with the lower mold 3, allowing the punch to automatically align and position itself axially, enabling the upper and lower molds to achieve dynamic self-centering. During the mold closing process, the punch 2 applies reverse extrusion force, causing the blank 5 to be extruded and deformed within the mold cavity, ultimately forming the required reverse extrusion tube. After the reverse extrusion forming is completed, the ejector 4 ejects the formed reverse extrusion tube from the mold, allowing it to proceed to subsequent processing stages.

[0037] In this embodiment, the mold closing clearance is 0.2±0.1mm (see...). Figure 1 The design of the mold closing gap ensures that an appropriate fitting gap is formed between the upper mold sleeve and the lower mold during mold closing, thereby ensuring the coaxiality and stability of the mold during mold closing, and further improving the wall thickness consistency and accuracy during the reverse extrusion tube forming process.

[0038] In this embodiment, because the mold closing clearance between the upper mold sleeve 1 and the lower mold 3 is small, a wedge-shaped structure is designed on the inner diameter of the upper mold sleeve 1 and the outer diameter of the lower mold 3 to facilitate centering and positioning, specifically as follows: Figure 4 As shown, the inner wall of the upper mold sleeve 1 is machined with a tapered guide surface 10 with a height of 50-80mm, and the outer edge of the lower mold 3 is provided with a tapered guide section 30 corresponding to the guide surface 10. The taper angle of the tapered guide surface 10 and the tapered guide section 30 is 1° to 50°. When the mold is closed, the tapered guide section 30 can automatically slide and guide along the tapered guide surface 10. Through the linear contact or surface contact between the tapered guide surface 10 and the tapered guide section 30, the mold closing trajectory is forcibly corrected, and the concentricity deviation between the punch 2 and the mold cavity is controlled within ±0.05mm. This effectively eliminates the radial offset caused by traditional split molds, ensures the uniformity of the annular gap formed when the mold cavity is closed, and controls the wall thickness difference of the reverse extrusion tube within the qualified range. This fundamentally solves the product defect problem caused by uneven wall thickness due to alignment deviation.

[0039] In this embodiment, the inner cavity of the lower die 3 is cylindrical and matches the outer diameter of the reverse extrusion tube, ensuring that the inner cavity of the lower die 3 can fit tightly with the outer wall of the reverse extrusion tube. This allows the reverse extrusion tube to maintain a stable outer diameter during the reverse extrusion molding process. The cylindrical inner cavity structure also effectively supports the molding process of the reverse extrusion tube and avoids deformation.

[0040] In this embodiment, the ejector 4 is coaxial with the inner cavity of the lower mold 3, and the lower mold 3 has a tapered inner cavity hole 31. The ejector 4 includes a top block 40, the outer wall of which is tapered and adapted to the inner cavity hole 31 of the lower mold 3. This allows the reverse extrusion tube to be smoothly pushed out of the mold after molding, and the tapered structure reduces friction during the ejection process.

[0041] In this embodiment, as Figure 4 As shown, the punch 2 includes a rod 2a and a working end 2b coaxially connected. One end of the rod 2a is connected to the upper die sleeve 1, and the other end is connected to the working end 2b. The outer wall of the working end 2b is provided with a transition slope 2c, which is a conical structure. Its outer diameter gradually increases from the rod 2a to the bottom surface of the working end 2b. This can effectively guide the blank to be evenly stressed during the reverse extrusion molding process, ensuring the molding quality of the reverse extrusion tube. At the same time, the conical transition slope helps to reduce the friction between the punch and the blank, improving molding efficiency and die life.

[0042] In this embodiment, as Figure 3 As shown, the gap 20 between the rod 2a and the inner wall of the lower die 3 is greater than the thickness of the reverse extrusion tube. This design ensures that when the punch 2 applies reverse extrusion force, it can effectively avoid direct contact between the rod 2a and the reverse extrusion tube, thereby reducing friction and resistance and improving the smoothness of the molding process.

[0043] In this embodiment, using alloy steel as the mold material can improve the durability and service life of the mold. The mold can be used to produce precision forgings not only on a die forging press, but also on a free forging press.

[0044] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0045] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A reverse extrusion tube production mold, characterized in that, It includes an upper die sleeve (1), a punch (2), a lower die (3), and an ejector (4); The inner wall of the upper mold sleeve (1) and the outer wall of the lower mold (3) form a nested fit; the difference between the outer diameter of the lower mold (3) and the inner diameter of the upper mold sleeve (1) is the mold closing clearance; The inner wall end face of the upper mold sleeve (1) and the top end face of the lower mold (3) form a closed mold cavity when the mold is closed. The punch (2) is fixed in the middle of the upper mold sleeve (1) and extends axially to apply a counter-extrusion force to the blank (5). The ejector (4) is located at the bottom of the lower mold (3) and is used to eject the formed reverse extrusion tube.

2. The reverse extrusion tube production mold as described in claim 1, characterized in that, The mold closing gap is 0.2±0.1mm.

3. The reverse extrusion tube production mold as described in claim 1, characterized in that, The upper mold sleeve (1) has an annular structure and its inner wall has a tapered guide surface (10). The outer edge of the lower mold (3) is provided with a tapered guide section (30) that matches the tapered guide surface (10) of the inner wall of the upper mold sleeve (1).

4. The reverse extrusion tube production mold as described in claim 3, characterized in that, The taper angle of the tapered guide surface (10) and the tapered guide section (30) is 1° to 50°.

5. The reverse extrusion tube production mold as described in claim 1, characterized in that, The inner cavity of the lower mold (3) is cylindrical and matches the outer diameter of the reverse extrusion tube.

6. The reverse extrusion tube production mold as described in claim 1, characterized in that, The ejector (4) is coaxial with the inner cavity of the lower mold (3).

7. The reverse extrusion tube production mold as described in claim 6, characterized in that, The lower mold (3) has a tapered inner cavity (31), and the ejector (4) includes a top block (40). The outer wall of the top block (40) is tapered and is adapted to the inner cavity (31) of the lower mold (3).

8. The reverse extrusion tube production mold as described in claim 1, characterized in that, The punch (2) includes a rod (2a) and a working end (2b) connected coaxially. One end of the rod (2a) is connected to the upper die sleeve (1), and the other end is connected to the working end (2b). The outer wall of the working end (2b) is a transition slope (2c), which is a conical structure with its outer diameter gradually increasing from the rod (2a) to the bottom surface of the working end (2b).

9. The reverse extrusion tube production mold as described in claim 8, characterized in that, The gap (20) between the rod (2a) and the inner wall of the lower die (3) is greater than the thickness of the reverse extrusion tube.

10. The reverse extrusion tube production mold as described in claim 1, characterized in that, The mold is made of alloy steel.

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