CN110560544B - Large-section-difference hollow structural member axial compression expansion forging process method - Google Patents
Large-section-difference hollow structural member axial compression expansion forging process method Download PDFInfo
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- CN110560544B CN110560544B CN201910990431.XA CN201910990431A CN110560544B CN 110560544 B CN110560544 B CN 110560544B CN 201910990431 A CN201910990431 A CN 201910990431A CN 110560544 B CN110560544 B CN 110560544B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
- B21D26/047—Mould construction
Abstract
A method for forming a hollow part, in particular to a method for carrying out axial compression and expansion forging on a hollow structural member with a large section difference. The invention solves the problem of wall thickness reduction in the existing high-pressure forming of parts with large section difference. The method comprises the following steps: firstly, manufacturing a large-section-difference preform, then filling fluid medium in the preform, namely changing a pipe into a solid bar, axially compressing a large-diameter area, and gradually attaching the mould to each part along with compression under the support of the internal medium; finally, the large-diameter area is further compressed to shorten the length of the large-diameter area and thicken the wall to a target value, and the forming is finished. The invention is a method for improving the uniformity of the wall thickness of the parts, and can also play a role in improving the shape precision.
Description
Technical Field
The invention relates to a forming method in the technical field of industrial manufacturing, in particular to a process method for axial compression and expansion forging of a large-section-difference hollow structural part.
Background
The large-section-difference reducer pipe is a key shape of an automobile exhaust system and is characterized by large section reducing rate which generally exceeds 1.5. The large-variable-diameter-rate part is manufactured by adopting a welding and assembling method at the earliest time, and has the defects of multiple working procedures, easy corrosion of a welding line, large welding thermal deformation and the like. With the improvement of the quality requirements of automobiles on the parts, the welding and assembling process cannot meet the high-quality manufacturing requirements. Hydroforming has been used in recent years to manufacture such parts. The introduction of welding seams is avoided in the hydraulic forming process, but the problem of wall thickness reduction exists, the wall thickness reduction rate of a large-diameter area exceeds 20%, and the use performance of parts is seriously reduced. Patent CN106311857A proposes a forming method capable of reducing wall thickness reduction, but the method is to compress the cross section, that is, the circumference of the cross section of the formed part is reduced, so that the method cannot be used for manufacturing parts with enlarged cross sections. More importantly, the wall thickness of the part cannot be uniform along the axial direction without improving the wall thickness. Aiming at the problem, the invention provides a method for improving the wall thickness uniformity of the parts, and simultaneously has the function of improving the shape precision.
Disclosure of Invention
In order to solve the problems, the invention provides a process method for axial compression and expansion forging of a large-section-difference hollow structural part.
The technical scheme adopted by the invention is as follows:
a large-section-difference hollow structural member axial compression expansion forging process method is characterized by comprising the following steps: the method comprises the following steps:
step one, forming a large-section-difference preformed part, wherein a diameter-changing process of hydraulic forming or spinning forming can be adopted; the preformed part is divided into three characteristic areas, namely a large-diameter area a, a transition area b and a small-diameter area c; in the diameter-changing process, the wall thickness of the large-diameter area is smaller than that of the transition area and the small-diameter area, and the preforming quality requirement of the preformed part is that the shape of the small-diameter area is the same as that of the small-diameter area of the final-formed part; the shape of the transition zone is close to that of a finished formed part, and the specific shape error is not more than 30%; the length of the large-diameter area is greater than that of the large-diameter area of the final forming part, and is 1% -50% greater than that of the large-diameter area of the final forming part; the perimeter of the section profile of the large-diameter area is not more than that of the section profile of the final forming part, and is specifically 0-20% smaller than that of the large-diameter area of the final forming part;
step two, a final forming die comprises an end part punch I, an end part punch II, an upper die and a lower die, the preformed part is placed in the lower die, the die is closed, then the preformed part is filled with fluid medium and sealed, namely the preformed part is converted into a solid structure,
step three, the first end punch and the second end punch push the large-diameter area along the axial direction, the pipe blank material moves to the area without being attached with the die under the support of the internal fluid medium, the die cavity of the die is filled, the deformation mode is similar to closed die forging,
step four, when the die attaching degree reaches more than 90%, controlling the supporting pressure p of the internal fluid medium through a pressure regulating valve, wherein the internal pressure p needs to ensure that the pipe blank attached to the die in the step five is always attached to the die cavity,
step five, the first end punch and the second end punch move in opposite directions continuously along the axial direction to compress the large-diameter area, so that the axial length of the large-diameter area is shortened, the wall thickness of the large-diameter area is thickened, when the wall thickness of the large-diameter area is thickened to a target value, the compression is stopped,
and sixthly, removing the internal fluid medium, opening the mold and taking out the final formed part.
The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make variations, modifications, additions or substitutions within the technical scope of the present invention.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with a manufacturing method of welding and assembling, the method has the advantages that no welding seam exists, the corrosion resistance of parts is good, the appearance is attractive, and the shape precision is high;
2. the large-diameter area of the formed part has no wall thickness reduction, and the structural performance is excellent;
3. the sticking dies are pressed to make the parts expand and stick the dies like air blowing balls instead of increasing the internal pressure, the required pressure is small, and particularly sharp contour lines can be formed;
4. the material is always in compression deformation in the forming process, and is not easy to break under the action of three-dimensional compressive stress, so that the technology can be used for forming low-plasticity materials;
the invention has reasonable design, reliable work, obvious effect and stronger popularization value.
Drawings
FIG. 1 is a schematic view of a preformed part and a final forming die.
FIG. 2 is a schematic view of the clamping of a preform part into a final mold.
FIG. 3 is a schematic view of the large diameter section a being pushed axially against the mold by 90%.
FIG. 4 is a schematic view of the pressure regulating tube blank attached to a mold cavity.
FIG. 5 is a schematic view of the compression of the large diameter area by moving the first end punch and the second end punch toward each other.
Fig. 6 shows a schematic view of the final-shaped part 7.
1-preformed part 2-end punch one 3-end punch two 4-upper die 5-lower die 6-pressure regulating valve 7-final formed part
Detailed Description
The present invention is described in further detail below with reference to the accompanying drawings and the detailed description, as shown in fig. 1-6.
The first method is as follows: step one, forming a large-section-difference pre-formed part (1), wherein a diameter-changing process of hydraulic forming or spinning forming can be adopted; dividing the preformed part (1) into three characteristic areas, namely a large-diameter area a, a transition area b and a small-diameter area c; in the diameter-changing process, the wall thickness of the large-diameter area a is smaller than that of the transition area b and the small-diameter area c, and the preforming quality requirement of the preformed part (1) is that the shape of the small-diameter area c is the same as that of the small-diameter area c of the final-formed part (7); the shape of the transition region b is close to that of a final forming part (7), and the specific shape error is not more than 30%; the length of the large-diameter area a is greater than that of the large-diameter area a of the final forming part (7), and is specifically 1-50% greater than that of the large-diameter area a of the final forming part (7); the perimeter of the section profile of the large-diameter area a is not more than that of the section profile of the final forming part (7), and is specifically 0-20% smaller than that of the large-diameter area a of the final forming part (7);
step two, a final forming die comprises an end punch I (2), an end punch II (3), an upper die (4) and a lower die (5), the preformed part (1) is placed into the lower die (5), the dies are closed, then the preformed part (1) is filled with fluid medium and sealed, which is equivalent to the step of converting the preformed part into a solid structure,
step three, the first end punch (2) and the second end punch (3) push the large-diameter area a along the axial direction, the tube blank material moves to an area without die attachment under the support of an internal fluid medium, the die cavity is filled, the deformation mode is similar to closed die forging,
step four, when the sticking degree reaches more than 90 percent, controlling the supporting pressure p of the internal fluid medium through a pressure regulating valve (6), wherein the internal pressure p needs to ensure that the pipe blank which is already attached to the mold in the step five is always attached to the mold cavity,
step five, continuously moving the end part punch I (2) and the end part punch II (3) in opposite directions along the axial direction to compress the large-diameter area a, so that the axial length of the large-diameter area a is shortened, the wall thickness of the large-diameter area a is thickened, when the wall thickness of the large-diameter area a is thickened to a target value, the compression is stopped,
and sixthly, removing the internal fluid medium, opening the mould and taking out the final forming part (7).
The second method comprises the following steps: the support pressure p in this embodiment is 1 to 1000 MPa. The rest is the same as the first embodiment.
Claims (3)
1. A large-section-difference hollow structural member axial compression expansion forging process method is characterized by comprising the following steps: the method comprises the following steps:
step one, forming a large-section-difference preformed part (1) through a diameter-changing process of hydraulic forming or spinning forming, and dividing the preformed part (1) into three characteristic areas, namely a large-diameter area a, a transition area b and a small-diameter area c; in the diameter-changing process, the wall thickness of the large-diameter area a is smaller than that of the transition area b and the small-diameter area c, and the preforming quality requirement of the preformed part (1) is that the shape of the small-diameter area c is the same as that of the small-diameter area c of the final-formed part (7); the shape of the transition region b is close to that of the transition region b of the final forming part (7), and the shape error is not more than 30%; the length of the large-diameter area a is 1-50% longer than that of the large-diameter area a of the final forming part (7); the perimeter of the cross-section outline of the large-diameter area a is 0 to 20 percent smaller than that of the cross-section outline of the large-diameter area a of the final forming part (7);
step two, a final forming die comprises an end punch I (2), an end punch II (3), an upper die (4) and a lower die (5), the preformed part (1) is placed into the lower die (5), the dies are closed, then the preformed part (1) is filled with fluid medium and sealed, which is equivalent to the step of converting the preformed part into a solid structure,
step three, the first end punch head (2) and the second end punch head (3) push the large-diameter area a along the axial direction, the pipe blank material moves to the area without being attached with the die under the support of the internal fluid medium, the die cavity is filled with the pipe blank material,
step four, when the sticking degree reaches more than 90 percent, controlling the internal pressure p supported by the internal fluid medium through a pressure regulating valve (6), wherein the internal pressure p needs to ensure that the pipe blank which is already attached to the mold in the step five is always attached to the mold cavity,
step five, continuously moving the end part punch I (2) and the end part punch II (3) in opposite directions along the axial direction to compress the large-diameter area a, so that the axial length of the large-diameter area a is shortened, the wall thickness of the large-diameter area a is thickened, when the wall thickness of the large-diameter area a is thickened to a target value, the compression is stopped,
and sixthly, removing the internal fluid medium, opening the mould and taking out the final forming part (7).
2. The axial compression and expansion forging process method for the large-section-difference hollow structural part according to claim 1, characterized by comprising the following steps of: the fluid medium is a liquid or a gas.
3. The axial compression and expansion forging process method for the large-section-difference hollow structural part according to claim 1, characterized by comprising the following steps of: the internal pressure p is 1-1000 MPa.
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| DE102020200853A1 (en) * | 2020-01-24 | 2021-07-29 | Volkswagen Aktiengesellschaft | Process for the forming production of a closed hollow shaft |
| CN111451351B (en) * | 2020-04-30 | 2022-08-09 | 初冠南 | Forming and integrating method for tubular part |
| CN113878016B (en) * | 2021-09-28 | 2024-03-08 | 上海孚庭科技有限公司 | Forming method of pipe fitting with complex section |
| CN114653806B (en) * | 2022-03-01 | 2023-12-22 | 哈尔滨工业大学（威海） | Preforming method for high-strength steel reducing tubular part |
| CN114789217A (en) * | 2022-04-27 | 2022-07-26 | 广东轻量科技发展有限责任公司 | Automobile axle housing, automobile axle housing mold and forming method |
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| JP4133465B2 (en) * | 2003-03-10 | 2008-08-13 | 新日本製鐵株式会社 | Hydroform processing method |
| JP2005288532A (en) * | 2004-04-05 | 2005-10-20 | Nippon Steel Corp | Hydroforming method |
| JP4630218B2 (en) * | 2006-04-11 | 2011-02-09 | 新日本製鐵株式会社 | Method and apparatus for detecting cracks in dies for hydroforming |
| BR112012019550B1 (en) * | 2010-02-04 | 2020-05-26 | Nippon Steel Corporation | HYDROFORMATION METHOD AND HYDROFORMATION DEVICE. |
| CN204448968U (en) * | 2015-02-14 | 2015-07-08 | 中国重型机械研究院股份公司 | A kind of pipe fitting internal high pressure forming device |
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Effective date of registration: 20230110 Address after: 264200 No. 2, Wenhua West Road, Shandong, Weihai Patentee after: HARBIN INSTITUTE OF TECHNOLOGY (WEIHAI) Patentee after: HIT (WEIHAI) INNOVATION PIONEER PARK Co.,Ltd. Address before: 264200 No. 2, Wenhua West Road, Shandong, Weihai Patentee before: HARBIN INSTITUTE OF TECHNOLOGY (WEIHAI) |
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