Hot gas expansion tube die
By using a split-type side-push plug and a high-temperature resistant sealing layer, the problems of sealing failure, wear and insufficient precision in hot gas expansion forming technology are solved, achieving efficient and reliable pipe forming and extending the service life of the mold.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHONGQING BOJUN IND TECH CO LTD
- Filing Date
- 2025-07-29
- Publication Date
- 2026-06-23
AI Technical Summary
In existing hot gas expansion forming technology, side-push plug sealing failure, end face wear, thermal fatigue cracks, and insufficient forming accuracy lead to poor forming quality and low production efficiency.
The design features a split-type side-push plug with a tapered head surface treated with nitriding to achieve a hardness ≥ HRC60. Combined with a high-temperature resistant sealing layer and a multi-pneumatic ejector assembly, it ensures sealing performance and demolding efficiency.
It improves the sealing reliability and forming accuracy of pipe fittings, extends mold life, reduces the risk of air leakage and maintenance costs, and improves production efficiency.
Smart Images
Figure CN224389728U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of automotive stamping parts manufacturing technology, specifically to a hot gas expansion tube mold for hot gas expansion forming process, which is particularly suitable for the production of high-strength, closed-section structural parts. Background Technology
[0002] With the rapid development of the automotive industry towards lightweighting, high strength, and environmental friendliness, thermoforming technology (also known as hot gas forming) has gained widespread attention and application in the automotive manufacturing field in recent years as a breakthrough process. This technology uses high-temperature, high-pressure gas to plastically process metal tubing or profiles, enabling the production of structural components with complex cross-sections that are lightweight and high-strength, significantly improving the flexibility and performance limits of vehicle body structure design. Especially in the field of new energy vehicles, thermoforming technology effectively balances vehicle safety performance and range requirements by producing high-strength, low-weight body parts, becoming an important technological means to promote the dual goals of green and safe automotive manufacturing. In recent years, with the continuous maturation of domestic production lines and the gradual reduction of manufacturing costs, thermoforming technology has gradually penetrated from high-end models to the mainstream market and is expected to become a standard process in next-generation vehicle body manufacturing. However, this technology still faces challenges in practical applications, such as efficiency optimization and breaking through material performance limits, to meet the automotive industry's continuous demand for higher performance and lower costs.
[0003] In the hot gas expansion forming process, the mold is one of the core pieces of equipment, and the side-push plug, as a key component, directly affects the forming quality and production efficiency. Traditional hot gas expansion tube molds typically have the following functions for their side-push plugs: first, to achieve high-pressure sealing, ensuring no leakage of high-temperature, high-pressure gas during forming; second, to withstand tens of tons of axial thrust transmitted by the hydraulic system to ensure the stability of the tube during forming; third, to integrate gas interface for the injection and discharge of high-temperature, high-pressure gas; and fourth, to incorporate cooling water channels in some designs to prevent deformation of the product due to high temperatures after demolding. These functions place extremely high demands on the structural design and material selection of the mold. However, existing side-push plugs have significant shortcomings, mainly in the following aspects:
[0004] 1. Sealing failure problem: Under high temperature and high pressure environment, the contact surface between the side push plug and the end of the pipe is prone to sealing failure due to repeated heating and high pressure impact, resulting in gas leakage, which in turn causes molding failure or product shape not meeting requirements.
[0005] 2. End face wear and thermal fatigue cracks: During the forming process, the side push plug needs to withstand the repeated action of high temperature and high pressure gas. The end face material is prone to wear, and thermal fatigue cracks are generated during the cyclic heating and cooling process, which shortens the service life of the mold and increases maintenance costs.
[0006] 3. Insufficient forming accuracy: In existing mold designs, axial feeding and radial bulging usually lack independent control, resulting in uneven stress during the forming process of pipe fittings, which affects the dimensional accuracy and performance consistency of the products.
[0007] 4. Low demolding efficiency: The demolding mechanism of traditional molds is relatively simple in design, and pipe parts are prone to jamming or damage during demolding, which affects production efficiency and product qualification rate. Utility Model Content
[0008] In view of this, the purpose of this utility model is to provide a hot gas expansion tube mold that solves the problems of side-push plug sealing failure, end face wear, thermal fatigue cracks and insufficient forming accuracy in the prior art, and ensures effective sealing of the tube end during high temperature and high pressure gas expansion forming process, thereby improving product forming quality and production efficiency.
[0009] To achieve the above objectives, this utility model provides the following technical solution:
[0010] A hot gas expansion tube mold includes an upper mold and a lower mold. When the upper mold and the lower mold are closed and spliced, a cavity for forming a tube is formed inside. A side push plug is provided on one side of the cavity and a stripping component is provided on the other side.
[0011] The bottom of the side-push plug is slidably mounted on one side of the cavity via a guide rail. One end of the side-push plug is connected to a hydraulic cylinder, and the other end of the side-push plug is conical with an internal air passage. Under the drive of the hydraulic cylinder, the conical end face of the side-push plug seals the end of the pipe fitting, and the pipe fitting is air-expanded and formed through the air passage inside the side-push plug.
[0012] The stripping assembly includes a pneumatic ejector rod and a push block. The push block is located outside the cavity and in contact with the tube. The pneumatic ejector rod is connected to the push block. When the mold is opened, the push block is driven to rise and push the tube out of the cavity to achieve stripping.
[0013] Furthermore, the lower mold includes a lower template, a fixing block, and a lower mold insert; the upper mold includes an upper template and an upper mold pressure plate insert; the fixing block is fixedly disposed on the lower template, and the lower mold insert is fixedly disposed on the fixing block; the upper mold pressure plate insert is fixedly disposed at the bottom of the upper template, and the lower mold insert and the upper mold pressure plate insert are closed and spliced to form a cavity.
[0014] Furthermore, the hydraulic cylinder is mounted on the lower template via a hydraulic cylinder fixing block, and the guide rail is fixedly mounted on the fixing block; the push block of the unloading assembly is slidably disposed in the fixing block.
[0015] Furthermore, the side-push plug adopts a split structure, including a detachable conical head and a main body. The surface of the conical head has a nitrided layer with a hardness ≥ HRC60 to enhance wear resistance and resistance to thermal fatigue cracking.
[0016] Furthermore, the contact surfaces of the upper die insert and the lower die insert are provided with a high-temperature resistant sealing layer to ensure the sealing of the cavity during the high-temperature and high-pressure gas expansion forming process.
[0017] Furthermore, the stripping assembly contains at least two pneumatic push rods that simultaneously drive the push block to move.
[0018] Furthermore, the lower mold is provided with a positioning pin, which cooperates with the outer contour of the tube to position the tube when it is placed into the cavity, preventing the tube from shifting during the forming process.
[0019] The beneficial effects of this utility model are as follows:
[0020] The hot gas expansion tube mold provided by this utility model has the following significant advantages compared with the prior art:
[0021] 1. Improved sealing performance and reduced risk of leakage: The split-type side-push plug is designed with a tapered head that undergoes surface nitriding treatment, achieving a hardness of HRC60 or higher, significantly enhancing wear resistance and resistance to thermal fatigue cracking. The tight fit between the tapered end face and the pipe end ensures reliable sealing during high-temperature and high-pressure gas injection, effectively preventing gas leakage and thus improving the pass rate of pipe forming.
[0022] 2. Improved forming accuracy: The mold employs a high-temperature resistant sealing layer on the contact surfaces of the upper mold insert and the lower mold insert to ensure the sealing of the cavity under high temperature and high pressure conditions, reducing the risk of deformation during the forming process. Simultaneously, the locating pins on the lower mold precisely match the outer contour of the pipe, effectively preventing displacement of the pipe during forming, further improving the dimensional accuracy and product consistency.
[0023] 3. Optimize demolding efficiency: The demolding assembly adopts a structure design of multiple pneumatic ejectors working together to drive the push block, ensuring uniform pushing force during demolding, reducing the possibility of pipe jamming or damage, and improving production efficiency and product surface quality.
[0024] 4. Extend mold life: The split structure of the side-push plug facilitates the replacement and maintenance of the conical head. Combined with the high-hardness surface treated by nitriding, it significantly extends the service life of the plug and reduces the maintenance cost of the mold.
[0025] In summary, this utility model, through structural optimization and material improvement, solves the shortcomings of traditional hot gas tube expansion molds in terms of sealing, precision, and demolding. It is suitable for round tube bulging processes, has high versatility and reliability, and provides an efficient and stable production solution for the automotive stamping parts manufacturing industry.
[0026] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description
[0027] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein:
[0028] Figure 1 This is a schematic diagram of the structure of the hot gas expansion tube mold in this utility model.
[0029] Figure 2 This is a schematic diagram of the side-push plug.
[0030] Reference numerals: 1-Upper mold plate; 2-Upper mold pressure plate insert; 3-Pipe fitting; 4-Lower mold insert; 5-Side push plug; 6-Hydraulic cylinder; 7-Slide rail; 8-Fixing block; 9-Upper mold plate; 10-Push block; 11-Pneumatic push rod; 12-Hydraulic cylinder fixing block. Detailed Implementation
[0031] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0032] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.
[0033] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0034] like Figures 1-2 As shown, this utility model provides a hot gas expansion tube mold, including an upper mold and a lower mold. The upper mold includes an upper template 1 and an upper mold pressure insert 2, and the lower mold includes a lower template 9, a fixing block 8, and a lower mold insert 4. When the upper template 1 and the lower template 9 are closed and spliced, the upper mold pressure insert 2 and the lower mold insert 4 together form a cavity for forming the tube 3. A side push plug 5 is provided on one side of the cavity, and a stripping assembly is provided on the other side.
[0035] The side-push plug 5 is slidably mounted on the fixed block 8 via a slide rail 7 at its bottom. One end of the side-push plug 5 is connected to a hydraulic cylinder 6, which is fixed to the lower template 9 via a hydraulic cylinder fixing block 12. The other end of the side-push plug 5 is conical and has an internal air passage. Driven by the hydraulic cylinder 6, the conical end face of the side-push plug 5 seals the end of the pipe fitting 3, and high-temperature, high-pressure gas is injected through the air passage to inflate and shape the pipe fitting 3. The side-push plug 5 adopts a split structure, including a detachable conical head and a main body. The surface of the conical head is nitrided to a hardness ≥ HRC60 to enhance wear resistance and resistance to thermal fatigue cracking.
[0036] The stripping assembly includes at least two pneumatic push rods 11 and push blocks 10. The push blocks 10 are located outside the cavity and in contact with the tube 3. The pneumatic push rods 11 are connected to the push blocks 10, and the push blocks 10 are slidably disposed in the fixed block 8. When the mold opens, the pneumatic push rods 11 drive the push blocks 10 to rise, pushing the tube 3 out of the cavity, thus achieving stripping.
[0037] The fixing block 8 is fixed to the lower mold plate 9, and the lower mold insert 4 is fixed to the fixing block 8. The upper mold pressure plate insert 2 is fixed to the bottom of the upper mold plate 1. The contact surface between the upper mold pressure plate insert 2 and the lower mold insert 4 is provided with a high-temperature resistant sealing layer to ensure the cavity sealing performance under high temperature and high pressure environment. The lower mold plate 9 is provided with a positioning pin, which cooperates with the outer contour of the tube 3 to prevent the tube 3 from shifting during the forming process.
[0038] Work process:
[0039] 1. Place the pipe fitting 3 into the cavity of the lower mold, and use the positioning pin to ensure that the pipe fitting 3 is accurately positioned.
[0040] 2. The upper template 1 and the lower template 9 are closed, and the upper mold pressure platen insert 2 and the lower mold insert 4 form a closed cavity. The high-temperature resistant sealing layer ensures a seal.
[0041] 3. The hydraulic cylinder 6 drives the side-push plug 5 to slide along the slide rail 7, and the conical end face seals the end of the pipe fitting 3. High temperature and high pressure gas is injected through the air passage to form air expansion.
[0042] 4. After forming is completed, the mold is opened, and the pneumatic push rod 11 drives the push block 10 to rise, pushing the tube 3 out of the cavity and completing the unloading.
[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A hot gas expansion tube mold, comprising an upper mold and a lower mold, wherein when the upper mold and the lower mold are closed and spliced, a cavity for forming a tube fitting is formed inside, characterized in that, A side-push plug is provided on one side of the cavity, and a material unloading assembly is provided on the other side; The bottom of the side-push plug is slidably mounted on one side of the cavity via a guide rail. One end of the side-push plug is connected to a hydraulic cylinder, and the other end of the side-push plug is conical with an internal air passage. Under the drive of the hydraulic cylinder, the conical end face of the side-push plug seals the end of the pipe fitting, and the pipe fitting is air-expanded and formed through the air passage inside the side-push plug. The stripping assembly includes a pneumatic ejector rod and a push block. The push block is located outside the cavity and in contact with the tube. The pneumatic ejector rod is connected to the push block. When the mold is opened, the push block is driven to rise and push the tube out of the cavity to achieve stripping.
2. The hot gas expansion tube mold according to claim 1, characterized in that, The lower mold includes a lower template, a fixing block, and a lower mold insert; the upper mold includes an upper template and an upper mold pressure plate insert; the fixing block is fixedly disposed on the lower template, and the lower mold insert is fixedly disposed on the fixing block; the upper mold pressure plate insert is fixedly disposed at the bottom of the upper template, and the lower mold insert and the upper mold pressure plate insert are closed and spliced to form a cavity.
3. The hot gas expansion tube mold according to claim 2, characterized in that, The hydraulic cylinder is mounted on the lower template via a hydraulic cylinder fixing block, and the guide rail is fixedly mounted on the fixing block; the push block of the unloading assembly is slidably mounted in the fixing block.
4. The hot gas expansion tube mold according to claim 1, characterized in that, The side-push plug adopts a split structure, including a detachable conical head and a main body. The surface of the conical head has a nitrided layer with a hardness ≥ HRC60 to enhance wear resistance and resistance to thermal fatigue cracking.
5. The hot gas expansion tube mold according to claim 1, characterized in that, The contact surfaces of the upper die insert and the lower die insert are provided with a high-temperature resistant sealing layer to ensure the sealing of the cavity during the high-temperature and high-pressure gas expansion forming process.
6. The hot gas expansion tube mold according to claim 1, characterized in that, The unloading assembly has at least two pneumatic push rods that simultaneously drive the push block to move.
7. The hot gas expansion tube mold according to claim 1, characterized in that, The lower mold is provided with a positioning pin, which cooperates with the outer contour of the tube to position the tube when it is placed into the cavity, preventing the tube from shifting during the forming process.