An aeronautical composite curved surface thermoforming machine
Patent Information
- Application Number
- CN202522027542.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-09-15
- Estimated Expiration
- 2035-09-22
AI Technical Summary
在现有技术中，现有的热成型机在进行真空压铸操作时，抽气系统的抽气效率较低，难以快速将模具型腔内部的空气抽净，导致型腔内部残留一定量的空气，真空抽气和墙内封闭能力不够好，热压精度相对不足，可能导致构件表面出现褶皱、凹陷等缺陷，且在合模压铸时，防偏移压铸精度相对不够好，无法精准高质量保持竖直精准压铸作业，进一步影响了精度压铸作用，由于压铸错位造成成型过程中无法紧密贴合模具表面，影响了曲面成型的精度，热形成完成度相对不足，难以满足航空领域对复合材料曲面构件的高精度和高质量要求，为此我们提出一种航空复合材料曲面热成型机来解决上述问题
[0011]与现有技术相比，本实用新型的优点和积极效果在于：
Smart Images
Figure CN224751874U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of curved surface thermoforming technology, and in particular to a curved surface thermoforming machine for aerospace composite materials. Background Technology
[0002] The aerospace composite material curved surface thermoforming machine is used to process aerospace composite materials into specific curved surface shapes. The curved surface thermoforming process typically involves first placing the aerospace composite material blank on the lower mold of a forming die. The blank is then heated by a heating device until it softens. The upper mold of the machine moves downwards under the drive mechanism, closing with the lower mold and applying pressure to the softened composite material blank, causing it to plastically deform according to the curved surface shape of the die, thereby forming the desired curved surface component. This facilitates curved surface thermoforming of aerospace composite materials. In existing technologies, the vacuum extraction efficiency of the existing thermoforming machine during vacuum die casting is low, making it difficult to quickly remove air from the mold cavity. This results in a certain amount of residual air inside the cavity, insufficient vacuum extraction and wall sealing capabilities, and relatively inadequate hot pressing precision. This can lead to defects such as wrinkles and dents on the surface of the component. Furthermore, the anti-displacement die casting precision is relatively poor during mold closing, making it impossible to maintain vertical precision during die casting, further affecting the precision die casting effect. Due to die casting misalignment, the surface cannot be tightly adhered to the mold surface during the forming process, affecting the precision of curved surface forming. The thermoforming completion is relatively insufficient, making it difficult to meet the high precision and high quality requirements of composite material curved surface components in the aerospace field. Therefore, we propose an aerospace composite material curved surface thermoforming machine to solve the above problems. Utility Model Content
[0003] In response to the problems raised, this utility model provides a thermoforming machine for curved surfaces of aerospace composite materials to solve the aforementioned problems.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: A thermoforming machine for curved surfaces of aerospace composite materials includes a hot pressing production table, the top of which is provided with a support frame; The top of the support frame is provided with a die-casting lifting cylinder, the bottom of the die-casting lifting cylinder is provided with a die-casting lifting plate, the top of the hot pressing production table is provided with a support positioning plate, and anti-deviation calibration seats that are sleeved and slidable at the support frame are bolted to the four corners of the die-casting lifting plate and the support positioning plate. Curved surface forming mold and top hot pressing mold are bolted to the opposite side of the die-casting lifting plate and the support positioning plate, respectively. The top of the hot pressing production platform is equipped with a vacuum pump that connects to the die-casting cavity of the curved surface forming mold. The curved surface forming mold and the top hot pressing mold are each equipped with a matching closed leak-proof ring on opposite sides.
[0005] Preferably, the support frame includes four support columns and one support plate. The four support columns are bolted to the four corners of the top of the hot pressing production table, and the tops of the four support columns are bolted to the four corners of the bottom of the support plate. The two die-casting lifting cylinders are symmetrically installed on the top of the support plate, and the bottoms of the die-casting lifting cylinders penetrate the support plate and are bolted to the top of the die-casting lifting plate.
[0006] Preferably, the eight anti-offset calibration seats are respectively sleeved and positioned on the four support columns, and the die-cast lifting plate and the supporting positioning plate are positioned and limited between the four support columns by the anti-offset calibration seats.
[0007] Preferably, the die-casting lifting plate and the supporting positioning plate are each provided with a limiting protection frame plate on their opposite sides. The curved surface forming mold and the top hot pressing mold are respectively inserted and bolted into the two limiting protection frame plates on their opposite sides. The supporting positioning plate is provided with auxiliary fixing pads on both sides. The two auxiliary fixing pads are bolted to the top of the hot pressing production table. The supporting positioning plate is bolted to the top of the hot pressing production table by the two auxiliary fixing pads.
[0008] Preferably, the eight anti-offset calibration seats are rectangularly bolted together at the four corners of the two die-casting lifting plates and the supporting positioning plate. The anti-offset calibration seats are semi-circular tubes that slide on the support column of the support frame. The top of the curved surface forming mold and the bottom of the top hot pressing mold are matched.
[0009] Preferably, the vacuum pump is installed and fixed on the top of the hot pressing production table, and a vacuum extraction pipe is provided at the end of the vacuum pump. The vacuum extraction pipe is connected to the die-casting cavity of the curved forming mold, and a pressure monitoring gauge and a switch control valve are provided on the vacuum extraction pipe.
[0010] Preferably, the closed leak-proof ring is a rubber elastic ring, and the curved surface forming mold and the top hot pressing mold are sealed by two closed leak-proof rings.
[0011] Compared with the prior art, the advantages and positive effects of this utility model are as follows: 1. This aerospace composite material curved surface thermoforming machine features a support frame on top of the hot pressing production table, which supports the die-casting lifting cylinder. Operating the die-casting lifting cylinder controls the lifting of the die-casting lifting plate. The die-casting lifting plate and the supporting positioning plate are respectively equipped with a curved surface forming mold and a top hot pressing mold on opposite sides. The die-casting lifting plate can drive the top hot pressing mold and the curved surface forming mold to close and hot press. Anti-deviation calibration seats are bolted to the four corners of the die-casting lifting plate and the supporting positioning plate. Multiple anti-deviation calibration seats are correspondingly sleeved and positioned on the support frame's pillars, providing precise positioning of the die-casting lifting plate and the supporting positioning plate. This results in high mold closing accuracy, high mold fitting quality, and excellent quality and precision in the curved surface thermoforming of materials. This also contributes to the excellent installation accuracy and mold closing calibration accuracy of the device, resulting in high mold fitting quality and excellent quality and precision in the curved surface thermoforming of materials.
[0012] 2. This aerospace composite material curved surface thermoforming machine has a vacuum pump connected to the die-casting cavity of the curved surface forming mold at the top of the hot pressing production table. The vacuum pump can perform vacuum adsorption operation on the die-casting cavity of the curved surface forming mold, which facilitates the fit of the molding. The curved surface forming mold and the top hot pressing mold are equipped with matching closed anti-leakage rings on opposite sides, which play a role in preventing vacuum leakage, further improving the molding accuracy, making the vacuum closure effect of the device cavity good, and improving the quality of vacuum hot pressing. Attached Figure Description
[0013] Figure 1 This utility model provides a frontal three-dimensional schematic diagram of a thermoforming machine for curved surfaces of aerospace composite materials; Figure 2 This utility model provides a front view sectional three-dimensional schematic diagram of a thermoforming machine for curved surfaces of aerospace composite materials; Figure 3 A top-view three-dimensional schematic diagram of a thermoforming machine for curved surfaces of aerospace composite materials is provided for this utility model; Figure 4 This is a frontal perspective three-dimensional schematic diagram of the connection structure between the support positioning plate and the curved surface forming mold of this utility model.
[0014] In the diagram: 1. Hot pressing production table; 2. Support column; 201. Support column; 202. Support plate; 3. Die-casting lifting cylinder; 4. Die-casting lifting plate; 5. Supporting positioning plate; 501. Limit protection frame plate; 502. Auxiliary fixing pad; 6. Anti-deviation calibration seat; 7. Curved surface forming mold; 8. Top hot pressing mold; 9. Vacuum pump; 901. Vacuum extraction pipe; 902. Pressure monitoring gauge; 903. Switch control valve body; 10. Closing anti-leakage ring. Detailed Implementation
[0015] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.
[0016] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed in the following specification.
[0017] Please see Figures 1-4 A thermoforming machine for curved surfaces of aerospace composite materials includes a hot press production table 1, and a support frame 2 is provided on the top of the hot press production table 1. The top of the support frame 2 is provided with a die-casting lifting cylinder 3, the bottom of the die-casting lifting cylinder 3 is provided with a die-casting lifting plate 4, the top of the hot pressing production table 1 is provided with a support positioning plate 5, and the four corners of the die-casting lifting plate 4 and the support positioning plate 5 are all bolted and fixed with anti-deviation calibration seats 6 that are sleeved and slid at the support of the support frame 2. The die-casting lifting plate 4 and the support positioning plate 5 are respectively bolted and fixed with curved surface forming mold 7 and top hot pressing mold 8 on opposite sides. The top of the hot pressing production table 1 is equipped with a vacuum pump 9 that connects to the die-casting cavity of the curved surface forming mold 7. The curved surface forming mold 7 and the top hot pressing mold 8 are equipped with matching closed anti-leakage rings 10 on opposite sides. The beneficial effects that this plan aims to achieve are: By providing a support frame 2 on the top of the hot pressing production table 1, the die-casting lifting cylinder 3 can be supported. Running the die-casting lifting cylinder 3 can control the lifting of the die-casting lifting plate 4. The die-casting lifting plate 4 and the support positioning plate 5 are respectively provided with a curved surface forming mold 7 and a top hot pressing mold 8 on opposite sides. The die-casting lifting plate 4 can drive the top hot pressing mold 8 and the curved surface forming mold 7 to close and hot press. Anti-deviation calibration seats 6 are bolted to the four corners of the die-casting lifting plate 4 and the support positioning plate 5. Multiple anti-deviation calibration seats 6 are correspondingly sleeved and positioned on the support frame 2, which can accurately position the die-casting lifting plate 4 and the support positioning plate 5, resulting in excellent quality and precision of curved surface hot forming of materials. The top of the hot pressing production table 1 is equipped with a vacuum pump 9 that connects to the die-casting cavity of the curved surface forming mold 7. The vacuum pump 9 can perform vacuum adsorption operation on the die-casting cavity of the curved surface forming mold 7, which facilitates the fit of the molding process. The curved surface forming mold 7 and the top hot pressing mold 8 are equipped with matching closed anti-leakage rings 10 on opposite sides, which play a role in preventing vacuum leakage. This ensures excellent installation accuracy and mold closing calibration accuracy of the device, high mold closing quality, excellent quality and accuracy of curved surface thermoforming of materials, and good vacuum closure effect of the inner cavity, thus improving the quality of vacuum hot pressing.
[0018] Furthermore, the support frame 2 includes four support columns 201 and a support plate 202. The four support columns 201 are bolted to the four corners of the top of the hot pressing production table 1, and the tops of the four support columns 201 are bolted to the four corners of the bottom of the support plate 202. Two die-casting lifting cylinders 3 are symmetrically installed on the top of the support plate 202. The bottom of the die-casting lifting cylinder 3 passes through the support plate 202 and is bolted to the top of the die-casting lifting plate 4. Specifically, the four support columns 201 can be stably bolted to the four corners of the top of the hot pressing production table 1, which can stably support the support plate 202, with excellent support adaptability. The support plate 202 can support the die-casting lifting cylinder 3 and has telescopic support adaptability.
[0019] Furthermore, eight anti-offset calibration seats 6 are respectively fitted and positioned on four support columns 201, and the die-cast lifting plate 4 and the supporting positioning plate 5 are positioned and limited between the four support columns 201 by the anti-offset calibration seats 6. Specifically, multiple anti-offset calibration seats 6 slide on four support columns 201 respectively, which facilitates the support of the die-casting lifting plate 4 and the support positioning plate 5. The support and positioning effect is good. When the die-casting lifting plate 4 is raised or lowered, it can be anti-offset calibrated by the anti-offset calibration seats 6. The calibration effect is good, the hot pressing is accurate and not easy to deviate, the molding accuracy is high, and the cost effect is good.
[0020] Furthermore, the die-casting lifting plate 4 and the supporting positioning plate 5 are each provided with a limiting protection frame plate 501 on the opposite side. The curved surface forming mold 7 and the top hot pressing mold 8 are respectively inserted and bolted into the two limiting protection frame plates 501 on opposite sides. The supporting positioning plate 5 is provided with auxiliary fixing pads 502 on both sides. The two auxiliary fixing pads 502 are bolted to the top of the hot pressing production table 1. The supporting positioning plate 5 is bolted to the top of the hot pressing production table 1 by the two auxiliary fixing pads 502. Specifically, the die-casting lifting plate 4 and the supporting positioning plate 5 are each provided with a limiting protection frame plate 501 on the opposite side. The limiting protection frame plate 501 can bolt and fix the curved surface forming mold 7 and the top hot pressing mold 8, making it convenient to disassemble and assemble the curved surface forming mold 7 and the top hot pressing mold 8, and the bolting and fixing are precise, with high hot pressing accuracy. The auxiliary fixing pad 502 is installed on both sides of the supporting positioning plate 5. The auxiliary fixing pad 502 can be bolted to the top of the hot pressing production table 1, with good installation and adaptation effect and good installation and fixing effect.
[0021] Furthermore, eight anti-offset calibration seats 6 are rectangularly bolted together at the four corners of the two die-casting lifting plates 4 and the supporting positioning plate 5. The anti-offset calibration seats 6 are semi-circular tubes that slide on the support column of the support frame 2. The top of the curved surface forming mold 7 and the bottom of the top hot pressing mold 8 are matched. Specifically, the anti-offset calibration seats 6 are rectangularly bolted to the four corners of the two die-casting lifting plates 4 and the supporting positioning plate 5. The die-casting lifting plates 4 and the supporting positioning plate 5 are precisely matched and positioned by different anti-offset calibration seats 6. During the lifting and hot pressing of the die-casting lifting plates 4, the anti-offset positioning effect is good and the forming accuracy is high. The top of the curved surface forming mold 7 and the bottom of the top hot pressing mold 8 are matched and the mold closing accuracy is high, the hot pressing effect is good, and the product quality is high.
[0022] Furthermore, the vacuum pump 9 is installed and fixed on the top of the hot press production table 1. The end of the vacuum pump 9 is provided with a vacuum extraction pipe 901, which is connected to the die-casting cavity of the curved forming mold 7. The vacuum extraction pipe 901 is provided with a pressure monitoring gauge 902 and a switch control valve body 903. Specifically, the vacuum pump 9 is installed and fixed at the top of the hot pressing production table 1. It can achieve vacuum extraction through the vacuum extraction pipe 901, which facilitates the vacuum extraction of the curved forming mold 7. As a result, air is not easily left inside the cavity during hot pressing, the hot pressing bending effect is good, and the forming accuracy is high. The vacuum extraction pipe 901 is equipped with a pressure monitoring gauge 902 and a switch control valve body 903. During the vacuum extraction, the pressure monitoring gauge 902 detects the pressure to maintain the vacuum state, and the switch control valve body 903 acts as a switch, which has a good switching control effect and is easy to operate.
[0023] Furthermore, the closed leak-proof ring 10 is a rubber elastic ring, and the curved surface forming mold 7 and the top hot pressing mold 8 are sealed by two closed leak-proof rings 10. Specifically, the closing anti-leakage ring 10 is a rubber elastic ring, which makes the curved surface forming mold 7 and the top hot pressing mold 8 have a good anti-leakage effect when the mold is closed, excellent closing ability, and facilitates vacuum pumping 9 to perform vacuum pumping, resulting in good performance.
[0024] How to use and how to work this device: A support frame 2 is provided on the top of the hot pressing production table 1 to support the die casting lifting cylinder 3. The operation of the die casting lifting cylinder 3 can control the lifting of the die casting lifting plate 4. A support positioning plate 5 is provided on the top of the hot pressing production table 1. A curved surface forming mold 7 and a top hot pressing mold 8 are respectively provided on the opposite side of the die casting lifting plate 4 and the support positioning plate 5. The die casting lifting plate 4 can drive the top hot pressing mold 8, so that the top hot pressing mold 8 can be closed with the curved surface forming mold 7 for hot pressing of the curved surface of aerospace composite materials. Anti-offset calibration seats 6 are bolted to the four corners of the die casting lifting plate 4 and the support positioning plate 5. Multiple anti-offset calibration seats 6 are correspondingly sleeved and positioned on the support frame 2 to accurately position the die casting lifting plate 4 and the support positioning plate 5. The mold closing accuracy is high, and the whole is easy to disassemble and install. The installation accuracy and mold closing calibration accuracy are excellent, the mold closing fit quality is high, and the quality and accuracy of the curved surface hot forming of the material are excellent. The top of the hot pressing production table 1 is equipped with a vacuum pump 9 that connects to the die-casting cavity of the curved surface forming mold 7. When the mold is closed, the vacuum pump 9 can perform vacuum adsorption on the die-casting cavity of the curved surface forming mold 7, which facilitates the fit of the hot pressing and prevents distortion due to air, thus improving the quality of the hot-pressed product. The curved surface forming mold 7 and the top hot pressing mold 8 are equipped with matching closed anti-leakage rings 10 on opposite sides. During hot pressing, the closed anti-leakage rings 10 can form a closed inner cavity, which plays a better closed vacuum role during vacuum evacuation, further improving the vacuum performance of the inner cavity and resulting in excellent vacuum hot pressing quality. The support frame 2 includes four support columns 201 and one support plate 202. The four support columns 201 can be stably bolted to the four corners of the top of the hot pressing production table 1, and can stably support the support plate 202. The support adaptability is excellent. The support plate 202 can support the die-casting lifting cylinder 3 and has telescopic support adaptability. Multiple anti-offset calibration seats 6 slide on four support columns 201 respectively, which facilitates the support of the die-casting lifting plate 4 and the support positioning plate 5. The support and positioning effect is good. When the die-casting lifting plate 4 is raised and lowered, it can be anti-offset calibrated by the anti-offset calibration seats 6. The calibration effect is good, the hot pressing is accurate and not easy to deviate, the molding accuracy is high, and the cost effect is good. Both the die-casting lifting plate 4 and the supporting positioning plate 5 are provided with a limiting protection frame plate 501 on the opposite side. The limiting protection frame plate 501 can bolt and fix the curved surface forming mold 7 and the top hot pressing mold 8, making it convenient to disassemble and assemble the curved surface forming mold 7 and the top hot pressing mold 8, and the bolting and fixing are precise, with high hot pressing accuracy. The auxiliary fixing pad 502 is installed on both sides of the supporting positioning plate 5. The auxiliary fixing pad 502 can be bolted to the top of the hot pressing production table 1, with good installation and adaptation effect and good installation and fixing effect. The anti-offset calibration seat 6 is rectangularly bolted to the four corners of the two die-casting lifting plates 4 and the supporting positioning plate 5. The die-casting lifting plates 4 and the supporting positioning plate 5 are precisely matched and positioned by different anti-offset calibration seats 6. During the lifting and hot pressing, the die-casting lifting plate 4 has a good anti-offset positioning effect and high forming accuracy. The top of the curved surface forming mold 7 and the bottom of the top hot pressing mold 8 are matched and matched, resulting in high mold closing accuracy, good hot pressing effect, and high product quality. The vacuum pump 9 is installed and fixed on the top of the hot pressing production table 1. It can achieve vacuum extraction through the vacuum extraction pipe 901, which facilitates the vacuum extraction of the curved forming mold 7. As a result, air is not easily left inside the cavity during hot pressing, the hot pressing bending effect is good, and the forming accuracy is high. The vacuum extraction pipe 901 is equipped with a pressure monitoring gauge 902 and a switch control valve body 903. During the vacuum extraction, the pressure monitoring gauge 902 detects the pressure to maintain the vacuum state, and the switch control valve body 903 acts as a switch, which has a good switching control effect and is easy to operate. The closing anti-leakage ring 10 is a rubber elastic ring, which makes the curved surface forming mold 7 and the top hot pressing mold 8 have a good anti-leakage effect when the mold is closed, excellent closing ability, and facilitates vacuum pumping 9 to perform vacuum pumping, resulting in good performance. The device boasts excellent installation and mold calibration accuracy, high mold fitting quality, and superior quality and precision in the thermoforming of curved surfaces of materials. Furthermore, it exhibits excellent vacuum closure within the cavity, thereby improving the quality of vacuum hot pressing and meeting the production requirements of composite materials in the aerospace field.
[0025] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the technical solution of the present utility model.
Claims
1. An aircraft composite curved surface thermoforming machine comprising a hot-press production table (1), characterized in that: The top of the hot pressing production table (1) is provided with a support frame (2). The top of the support frame (2) is provided with a die-casting lifting cylinder (3), the bottom of the die-casting lifting cylinder (3) is provided with a die-casting lifting plate (4), the top of the hot pressing production table (1) is provided with a support positioning plate (5), and the four corners of the die-casting lifting plate (4) and the support positioning plate (5) are all bolted with anti-offset calibration seats (6) that are slidably attached to the support frame (2) of the support frame (2). The die-casting lifting plate (4) and the support positioning plate (5) are respectively bolted with curved surface forming mold (7) and top hot pressing mold (8) on opposite sides. The top of the hot pressing production platform (1) is provided with a vacuum pump (9) that connects to the die-casting cavity of the curved surface forming mold (7). The curved surface forming mold (7) and the top hot pressing mold (8) are each provided with a matching closed leak-proof ring (10) on opposite sides.
2. An aircraft composite curved thermoforming machine as claimed in claim 1, wherein: The support frame (2) includes four support columns (201) and a support plate (202). The four support columns (201) are bolted to the four corners of the top of the hot pressing production table (1). The tops of the four support columns (201) are bolted to the four corners of the bottom of the support plate (202). The two die-casting lifting cylinders (3) are symmetrically installed on the top of the support plate (202). The bottom of the die-casting lifting cylinder (3) penetrates the support plate (202) and is bolted to the top of the die-casting lifting plate (4).
3. An aircraft composite curved thermoforming machine as claimed in claim 2, wherein: The eight anti-offset calibration seats (6) are respectively fitted and positioned on the four support columns (201), and the die-cast lifting plate (4) and the supporting positioning plate (5) are positioned and limited between the four support columns (201) by the anti-offset calibration seats (6).
4. The aerospace composite material curved surface thermoforming machine according to claim 1, characterized in that: The die-casting lifting plate (4) and the support positioning plate (5) are provided with a limiting protection frame plate (501) on opposite sides. The curved surface forming mold (7) and the top hot pressing mold (8) are respectively inserted and bolted into the two limiting protection frame plates (501) on opposite sides. The support positioning plate (5) is provided with auxiliary fixing pads (502) on both sides. The two auxiliary fixing pads (502) are bolted to the top of the hot pressing production table (1). The support positioning plate (5) is bolted to the top of the hot pressing production table (1) by the two auxiliary fixing pads (502).
5. The aerospace composite material curved surface thermoforming machine according to claim 1, characterized in that: The eight anti-offset calibration seats (6) are rectangularly bolted together at the four corners of the two die-casting lifting plates (4) and the supporting positioning plate (5). The anti-offset calibration seats (6) are semi-circular tubes that slide on the support column of the support frame (2). The top of the curved surface forming mold (7) and the bottom of the top hot pressing mold (8) are matched.
6. The aerospace composite material curved surface thermoforming machine according to claim 1, characterized in that: The vacuum pump (9) is installed and fixed on the top of the hot press production table (1). The vacuum pump (9) has a vacuum pipe (901) at its end. The vacuum pipe (901) is connected to the die-casting cavity of the curved surface forming mold (7). The vacuum pipe (901) is equipped with a pressure monitoring gauge (902) and a switch control valve body (903).
7. The aerospace composite material curved surface thermoforming machine according to claim 1, characterized in that: The closed leak-proof ring (10) is a rubber elastic ring, and the curved surface forming mold (7) and the top hot pressing mold (8) are sealed by two closed leak-proof rings (10).