Tube forming device

Abstract

The utility model relates to a kind of pipe forming device, it includes shell, sleeve located in shell and plug rod located in sleeve, sleeve includes first circumferential wall portion, second circumferential wall portion and third circumferential wall portion between first circumferential wall portion and second circumferential wall portion and connect the two along the longitudinal axis of pipe forming device, first circumferential wall portion has constant first diameter, second circumferential wall portion has constant second diameter smaller than first diameter, the diameter of third circumferential wall portion gradually reduces from first diameter to second diameter along the longitudinal axis of pipe forming device.

Description

Technical Field

[0001] This utility model relates to a tube forming device, and more particularly to a tungsten tube forming tool. Technical Background

[0002] Tungsten tubes, as a type of refractory metal tubing with high melting point and high strength, are widely used in high-temperature furnaces, vacuum electronic devices, aerospace, and other fields. Traditional tungsten tube manufacturing processes typically employ powder metallurgy isostatic pressing technology, which involves loading tungsten powder into a mold, applying high pressure to form a green blank, and then sintering it at high temperature to obtain a dense tungsten tube. However, the forming tooling in existing technologies suffers from the following significant problems.

[0003] The use of straight-cylinder tooling leads to significant material waste. Traditional tungsten tube forming tooling employs a simple straight-cylinder structure (i.e., a constant inner diameter sleeve), producing green blanks of uniform diameter cylinders. Since straight-cylinder tooling cannot directly form variable-diameter structures, production requires overfeeding, leaving a large allowance, and then removing the excess material through subsequent machining (such as turning or grinding) to ultimately achieve the desired shape. This process results in extremely low material utilization, causing a severe waste of expensive tungsten powder resources and persistently high production costs.

[0004] The machining process is time-consuming and inefficient. Because the shape of the green blank formed by the straight tooling differs greatly from that of the final product, a large amount of excess material needs to be removed during subsequent machining, resulting in long green blank filling time, time-consuming turning process, and difficulty in controlling machining accuracy.

[0005] Tooling structure limits production efficiency. Traditional tooling typically adopts a one-piece design, meaning the sleeve and outer shell are fixedly connected or machined as a single unit. This structure has the following drawbacks: difficulty in demolding green blanks, inconvenient mold maintenance, and poor adaptability.

[0006] Therefore, there is an urgent need for a new type of tube forming device that can directly produce green blanks with variable diameter structures, reduce machining work, and at the same time take into account the convenience of demolding and the efficiency of mold maintenance. Utility Model Content

[0007] This utility model aims to significantly improve material utilization, shorten green billet filling time, and greatly reduce green billet turning time through the design of a variable diameter sleeve, which meets the core needs of cost reduction and efficiency improvement in modern manufacturing.

[0008] The tube forming device according to this utility model includes a shell, a sleeve located inside the shell, and a mandrel located inside the sleeve. The sleeve, along the longitudinal axis of the tube forming device, includes a first circumferential wall portion, a second circumferential wall portion, and a third circumferential wall portion located between and connecting the first and second circumferential wall portions. The first circumferential wall portion has a constant first diameter, the second circumferential wall portion has a constant second diameter smaller than the first diameter, and the diameter of the third circumferential wall portion gradually decreases from the first diameter to the second diameter along the longitudinal axis of the tube forming device. The tube forming device according to this utility model achieves a variable diameter sleeve design or a slimmer waist design through the second circumferential wall portion with a smaller diameter and the third circumferential wall portion with a transition diameter, resulting in a variable diameter green blank, thereby effectively reducing the material feeding weight and the green blank filling and machining time.

[0009] In a variation of the present invention, the sleeve further includes a fourth wall portion and a fifth wall portion, the fourth wall portion being located between and connecting the second circumferential wall portion and the fifth circumferential wall portion. In a preferred embodiment of the present invention, the fifth wall portion has a constant fifth diameter equal to the first diameter of the first circumferential wall portion, and the diameter of the fourth wall portion gradually increases from the second diameter to the fifth diameter along the longitudinal axis of the tube forming device. The arrangement of the fourth and fifth wall portions further highlights the variable diameter sleeve design of the present invention, giving the sleeve an overall structure with a large diameter at the top and bottom and a small diameter in the middle, directly forming a slimmer waist structure, making the green shape closer to the final product, and reducing machining allowance.

[0010] In one variation of this utility model, the outer shell has a shape consistent with that of the sleeve. The consistency between the outer shell and the sleeve shape (i.e., the inner wall of the outer shell completely fits the outer wall of the sleeve) ensures that the isostatic pressure is evenly transmitted throughout the entire sleeve, guaranteeing that the narrower portion and both ends bear the same pressure. This prevents cracking or deformation of the green blank due to excessively low local density, improves the overall density of the green blank, and reduces product defects after sintering.

[0011] In one variation of this utility model, the outer shell includes a first outer shell portion with a shape consistent with the first circumferential wall portion, a second outer shell portion with a shape consistent with the second circumferential wall portion, a third outer shell portion with a shape consistent with the third circumferential wall portion, a fourth outer shell portion with a shape consistent with the fourth circumferential wall portion, a fifth outer shell portion with a shape consistent with the fifth circumferential wall portion, and a base. The outer shell synchronously changes diameter with the sleeve, providing precise support for the diameter-changing areas of the sleeve (such as the third and fourth circumferential wall portions), thereby reducing the elastic deformation of the sleeve under high pressure; reducing mold fatigue damage; and extending the service life of the tooling.

[0012] In a preferred embodiment of the present invention, the first outer shell portion is detachably connected to the third outer shell portion. The detachable shell achieves several advantages through its split design: quick assembly and disassembly, i.e., the shell and sleeve adopt a split structure (such as flange bolt connection), allowing for segmented disassembly during demolding of the green blank, avoiding damage caused by forced ejection; modular maintenance, i.e., only the corresponding module needs to be replaced when a single component is damaged, reducing maintenance costs; and enhanced adaptability, i.e., different specifications of products can be quickly adapted by adjusting the combination of sleeves with different diameters.

[0013] In a preferred embodiment of the present invention, the lower end of the first housing portion includes a first circumferential flange, and the upper end of the third housing portion includes a third circumferential flange, the first circumferential flange being detachably connected to the third circumferential flange. The first and third circumferential flanges particularly advantageously enable quick assembly and disassembly of the housing and modular maintenance.

[0014] In one variation of the present invention, one or more holes are provided on the outer wall of the outer shell (10). The holes on the outer wall of the outer shell serve as exhaust channels, allowing gas to escape quickly during pressing, thereby reducing internal defects in the green body and improving the product qualification rate; ensuring uniform compression of powder and improving the overall density of the green body.

[0015] In one variation of this invention, the ratio of the difference between the first diameter (211) and the second diameter (221) to the first diameter (211) is between 0.01 and 0.2. This optimized ratio of 0.01-0.2 achieves the best balance in the waist-slimming structure: the diameter difference is sufficiently significant (saving 20-40% of waist material) without affecting the pressing quality, and the measured material utilization rate remains stable in the 60-70% range.

[0016] In one variation of this invention, the ratio of the axial length of the third circumferential wall portion along the longitudinal axis of the tube forming device to the axial length of the second circumferential wall portion along the longitudinal axis of the tube forming device is between 0.02 and 0.4. By controlling the ratio of the axial length of the third circumferential wall portion to the second circumferential wall portion within the range of 0.02-0.4, the axial compressive strength of the transition zone can be improved, preventing the slender waist area from becoming a mechanically weak point. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example in the corresponding accompanying drawings. These illustrative descriptions do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 This is a schematic diagram of the outer casing of a tube forming apparatus based on existing technology;

[0019] Figure 2 This is a schematic diagram of the sleeve of a tube forming device based on existing technology;

[0020] Figure 3 This is a schematic diagram of a green blank prepared using a tube forming device based on existing technology;

[0021] Figure 4 This is a schematic diagram of the outer shell of the tube forming device according to this utility model;

[0022] Figure 5 This is a schematic diagram of the sleeve of the tube forming device according to this utility model;

[0023] Figure 6 This is a schematic diagram of the green blank prepared according to the tube forming device of this utility model;

[0024] Figure 7 This is a schematic diagram of the final processed product of the green blank prepared according to the tube forming device of this utility model. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the various embodiments of this utility model will be described in detail below with reference to the accompanying drawings. The following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to illustrate selected embodiments of the utility model. The technical solutions claimed by this utility model can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0026] In the description of this utility model, the terms "first", "second", and "third" are used only to describe features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of the indicated technical features.

[0027] In the description of this utility model, unless otherwise explicitly defined, terms such as "provided," "set up," "connected," and "linked" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0028] Figures 1-3A schematic diagram of a tube forming apparatus according to the prior art and the green blank produced therefrom is shown. In the conventional straight-tube tooling, the tungsten tube shell 10' and sleeve 20' are both cylinders of equal diameter, and the green blank 40' formed by pressing is also cylindrical. In the straight-tube mold, tungsten powder can only be overfilled during production, and the excess material is then removed through subsequent machining, resulting in significant material waste. The finished product weight accounts for only about 30% of the initial feed, with 70% of the tungsten powder being cut away. Costs are high, as tungsten is a high-value rare metal, and overfilling significantly increases raw material costs. Furthermore, in the traditional process, the straight-tube green blank requires turning to remove a large amount of material to form a slender structure, resulting in a large machining allowance. Most of the material in the middle of the tube needs to be cut away, which is time-consuming; tool wear is rapid, and the high hardness of tungsten exacerbates tool wear during prolonged cutting, increasing production costs. Moreover, the traditional straight-tube tooling is an integrated mold, which has many drawbacks, such as difficulty in demolding and inconvenient maintenance.

[0029] The following is combined Figures 4 to 7 The following is a further detailed description of the tube forming apparatus 1 according to the present invention.

[0030] like Figure 4 and Figure 5 As shown, a tube forming apparatus 1 according to the present invention, preferably a tungsten tube forming fixture, includes a housing 10, a sleeve 20 located within the housing 10, and a mandrel 30 located within the sleeve 20. The sleeve 20, along the longitudinal axis X of the tube forming apparatus 1, includes a first circumferential wall portion 21, a second circumferential wall portion 22, and a third circumferential wall portion 23 located between the first circumferential wall portion 21 and the second circumferential wall portion 22 and connecting the two. Figure 5 As shown, the first circumferential wall portion 21 has a constant first diameter 211, the second circumferential wall portion 22 has a constant second diameter 221 smaller than the first diameter 211, and the diameter of the third circumferential wall portion 23 gradually decreases from the first diameter 211 to the second diameter 221 along the longitudinal axis X of the tube forming device 1. The tube forming device according to this invention achieves a variable diameter sleeve design or a slimmer waist design through the second circumferential wall portion 22 with a smaller diameter and the third circumferential wall portion 23 with a transition diameter, thus giving the formed green blank a variable diameter characteristic, effectively reducing the material feeding weight and the green blank filling and machining time.

[0031] In one embodiment of the present invention, the sleeve 20 further includes a fourth wall portion 24 and a fifth wall portion 25, the fourth wall portion 24 being located between and connecting the second circumferential wall portion 22 and the fifth circumferential wall portion 25. In a preferred embodiment, the fifth wall portion 25 has a constant fifth diameter 251 equal to the first diameter 211 of the first circumferential wall portion 21, and the diameter of the fourth wall portion 24 gradually increases from the second diameter 221 to the fifth diameter 251 along the longitudinal axis X of the tube forming apparatus 1. In this embodiment, the sleeve 20 includes, along the longitudinal axis X of the tube forming apparatus 1, a first circumferential wall portion 21, a second circumferential wall portion 22, a third circumferential wall portion 23 located between and connecting the first circumferential wall portion 21 and the second circumferential wall portion 22, a fourth wall portion 24 located below the second circumferential wall portion 22, and a fifth circumferential wall portion 25 located below the fourth wall portion 24. Preferably, the first circumferential wall portion 21 and the fifth circumferential wall portion 25 have the same constant diameter. Preferably, both the third circumferential wall portion 23 and the fourth wall portion 24 have gradually changing diameters and are symmetrical relative to the second circumferential wall portion 22, which has a smaller diameter. That is, the third circumferential wall portion 23 and the fourth wall portion 24 have the same axial length and transition slope. In this structure, the sleeve 20, as a whole, has a structure with large diameters at the top and bottom, a small diameter in the middle, and a transition section, directly forming a slender waist structure, making the green shape closer to the final product and reducing machining allowance.

[0032] In one embodiment of the present invention, the outer shell 10 has a shape consistent with that of the sleeve 20. The inner wall of the outer shell 10 fits against the outer wall of the sleeve 20, so that the isostatic pressure is evenly transmitted to the entire sleeve, ensuring that the waist section and both ends bear the same pressure, thereby avoiding cracking or deformation of the green blank caused by local low density; improving the overall density of the green blank and reducing product defects after sintering.

[0033] In one embodiment of the present invention, the outer shell 10 includes a first outer shell portion 11 with a shape consistent with the first circumferential wall portion 21, a second outer shell portion 12 with a shape consistent with the second circumferential wall portion 22, a third outer shell portion 13 with a shape consistent with the third circumferential wall portion 23, a fourth outer shell portion 14 with a shape consistent with the fourth circumferential wall portion 24, a fifth outer shell portion 15 with a shape consistent with the fifth circumferential wall portion 25, and a base 16. That is, similar to the overall shape of the sleeve 20, the outer shell 10 also has a structure with a large diameter at the top and bottom, a small diameter in the middle, and a transition section, thereby providing precise support for the variable diameter areas of the sleeve (such as the third circumferential wall portion 23 and the fourth circumferential wall portion 24), thereby reducing the elastic deformation of the sleeve under high pressure.

[0034] In one embodiment of the present invention, the first housing portion 11 is detachably connected to the third housing portion 13. In a preferred embodiment, the lower end of the first housing portion 11 includes a first circumferential flange 111, and the upper end of the third housing portion 13 includes a third circumferential flange 131, with the first circumferential flange 111 detachably connected to the third circumferential flange 131. The detachable housing achieves advantageous technical effects such as quick assembly and disassembly, modular maintenance, and enhanced adaptability through its split design.

[0035] In one embodiment of the present invention, one or more holes are provided on the outer wall of the outer casing 10. In a preferred embodiment, the one or more holes are evenly distributed circumferentially on one or more of the first outer casing portion 11, the second outer casing portion 12, the third outer casing portion 13, the fourth outer casing portion 14, and the fifth outer casing portion 15 of the outer casing 10. The holes on the outer wall of the outer casing serve as exhaust channels, allowing gas to escape quickly during pressing, thereby reducing internal defects in the green body and improving the product yield; ensuring uniform powder compression and improving the overall density of the green body.

[0036] In one embodiment of the present invention, the ratio of the difference between the first diameter 211 of the first circumferential wall portion 21 and the second diameter 221 of the second circumferential wall portion 22 to the first diameter 211 of the first circumferential wall portion 21 is between 0.01 and 0.2, preferably between 0.05 and 0.15. Similarly, the ratio of the difference between the first diameter 251 of the fifth circumferential wall portion 25 and the second diameter 221 of the second circumferential wall portion 22 to the first diameter 251 of the fifth circumferential wall portion 25 is between 0.01 and 0.2, preferably between 0.05 and 0.15. By optimizing the ratio, an optimal balance of the waist-slimming structure is achieved: the diameter difference is sufficiently significant (saving 20-40% of waist material) without affecting the pressing quality, and the measured material utilization rate is consistently in the 60-70% range.

[0037] In one embodiment of the present invention, the ratio of the axial length L23 of the third circumferential wall portion 23 along the longitudinal axis X of the tube forming device 1 to the axial length L22 of the second circumferential wall portion 22 along the longitudinal axis X of the tube forming device 1 is between 0.02 and 0.4, preferably between 0.05 and 0.2. Similarly, the ratio of the axial length of the fourth circumferential wall portion 24 along the longitudinal axis X of the tube forming device 1 to the axial length of the second circumferential wall portion 22 along the longitudinal axis X of the tube forming device 1 is between 0.02 and 0.4, preferably between 0.05 and 0.2. Having an optimized axial length ratio can improve the axial compressive strength of the transition zone and prevent the slender waist area from becoming a mechanically weak point.

[0038] Figure 6 A schematic diagram of the green blank 40 prepared by the tube forming apparatus according to the present invention is shown. Figure 7 This is a schematic diagram of the final processed product of the green blank 40 prepared according to the tube forming apparatus of this utility model. Figure 6 As shown, the green blank 40 prepared by the tube forming device according to this utility model also has a waist-shaped design 401 corresponding to the variable diameter design of the sleeve 20, so that the shape of the green blank is closer to the final product and the machining allowance is reduced.

[0039] The applicant compared the processing using the tube forming device according to this utility model with that of a conventional tube forming device in the prior art, and found that the tube forming device according to this utility model improves material utilization, increasing the ratio of finished product to raw material from about 30% to 60-70%. Furthermore, it saves processing time; the green blank filling time is reduced from the traditional 6 hours to 4 hours, increasing filling efficiency by 50%; and the green blank turning time is reduced from the traditional 12 hours to 7 hours, increasing green blank turning efficiency by 71.43%.

[0040] Therefore, the tube forming apparatus according to this utility model has achieved significant advantages in at least the following aspects:

[0041] 1. Significantly improved material utilization. A slimmer structure is formed directly during the green forming stage, making the green shape closer to the final product and reducing machining allowance. The optimized mold structure allows for the calculation of the required tungsten powder amount based on the actual product shape, avoiding overfilling. Actual test data shows that the ratio of finished product to raw material increases from 30% to 60-70%, and material costs are reduced by more than 40%.

[0042] 2. Reduced green compact filling time. The sleeve and outer shell adopt a detachable structure, facilitating segmented filling during powder loading and reducing uneven powder accumulation. The gradient design of the narrower section (third circumferential wall) makes tungsten powder easier to distribute evenly, reducing manual intervention. Actual test data shows that the green compact filling time is reduced from 6 hours to 4 hours, improving efficiency by 50%, while also reducing the labor intensity of operators.

[0043] 3. Significantly reduced green blank turning time. The variable-diameter die directly presses out a slimmer structure, requiring only minimal finishing during machining, reducing turning allowance by over 50%. Tool life is extended; with reduced cutting depth, tool wear is slowed, and tool replacement frequency decreases. Machining accuracy is improved, reducing the risk of cutting deformation and resulting in better product dimensional consistency. Actual test data shows that turning time is reduced from 12 hours to 7 hours, efficiency is increased by 71.43%, and tool costs are reduced by 30%.

[0044] 4. The split design enhances ease of operation. The outer shell and sleeve adopt a split structure (such as flange bolt connection), which can be disassembled in sections when the blank is demolded, avoiding damage caused by forced ejection; if a single part is damaged, only the corresponding module needs to be replaced, reducing maintenance costs; enhanced adaptability: by adjusting the combination of sleeves with different diameters, it can be quickly adapted to different specifications of products.

[0045] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A tube forming apparatus (1), characterized in that, The tube forming device (1) includes a housing (10), a sleeve (20) located inside the housing (10), and a mandrel (30) located inside the sleeve (20). The sleeve (20) includes a first circumferential wall portion (21), a second circumferential wall portion (22), and a third circumferential wall portion (23) located between and connecting the first circumferential wall portion (21) and the second circumferential wall portion (22). The first circumferential wall portion (21) has a constant first diameter (211), the second circumferential wall portion (22) has a constant second diameter (221) smaller than the first diameter (211), and the diameter of the third circumferential wall portion (23) gradually decreases from the first diameter (211) to the second diameter (221) along the longitudinal axis (X) of the tube forming device (1).

2. The tube forming apparatus (1) according to claim 1, characterized in that, The sleeve (20) further includes a fourth circumferential wall portion (24) and a fifth circumferential wall portion (25), the fourth circumferential wall portion (24) being located between and connecting the second circumferential wall portion (22) and the fifth circumferential wall portion (25).

3. The tube forming apparatus (1) according to claim 2, characterized in that, The fifth circumferential wall portion (25) has a constant fifth diameter (251) equal to the first diameter (211) of the first circumferential wall portion (21), and the diameter of the fourth circumferential wall portion (24) gradually increases from the second diameter (221) to the fifth diameter (251) along the longitudinal axis (X) of the tube forming device (1).

4. The tube forming apparatus (1) according to any one of claims 1 to 3, characterized in that, The outer shell (10) has a shape that matches the shape of the sleeve (20).

5. The tube forming apparatus (1) according to claim 2, characterized in that, The outer shell (10) includes a first outer shell portion (11) with the shape of the first circumferential wall portion (21), a second outer shell portion (12) with the shape of the second circumferential wall portion (22), a third outer shell portion (13) with the shape of the third circumferential wall portion (23), a fourth outer shell portion (14) with the shape of the fourth circumferential wall portion (24), a fifth outer shell portion (15) with the shape of the fifth circumferential wall portion (25), and a base (16).

6. The tube forming apparatus (1) according to claim 5, characterized in that, The first housing portion (11) is detachably connected to the third housing portion (13).

7. The tube forming apparatus (1) according to claim 6, characterized in that, The lower end of the first housing portion (11) includes a first circumferential flange (111), and the upper end of the third housing portion (13) includes a third circumferential flange (131). The first circumferential flange (111) is detachably connected to the third circumferential flange (131).

8. The tube forming apparatus (1) according to any one of claims 1 to 3, characterized in that, One or more holes are provided on the outer wall of the outer casing (10).

9. The tube forming apparatus (1) according to any one of claims 1 to 3, characterized in that, The ratio of the difference between the first diameter (211) and the second diameter (221) to the first diameter (211) is between 0.01 and 0.

2.

10. The tube forming apparatus (1) according to any one of claims 1 to 3, characterized in that, The ratio of the axial length (L23) of the third circumferential wall portion (23) along the longitudinal axis (X) of the tube forming device (1) to the axial length (L22) of the second circumferential wall portion (22) along the longitudinal axis (X) of the tube forming device (1) is between 0.02 and 0.4.

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