Press machine for manufacturing polytetrafluoroethylene sealing ring

Abstract

The utility model relates to a press machine for manufacturing a polytetrafluoroethylene sealing ring, and belongs to the field of press machines. The forming mold is used for containing raw materials; the stamping device comprises a hydraulic cylinder, the hydraulic cylinder is arranged at the top of the rack, the hydraulic cylinder is provided with a telescopic rod, the telescopic rod is connected with a pressing plate, and the pressing plate moves along with the telescopic rod and can extrude the forming die; the cutting device comprises a cutter and a chuck used for fixing the sealing ring, the cutter is arranged on the rack, the chuck is connected with a sliding assembly, the sliding assembly can drive the chuck to move in the direction close to or away from the cutter, and when the chuck moves to the position close to the cutter, the chuck drives the sealing ring to rotate, and the cutter cuts the sealing ring. The sealing ring production line has the effects of reducing manpower consumption and improving the production efficiency of sealing rings.

Description

Technical Field

[0001] The present application relates to the field of presses, and more particularly to a press for manufacturing polytetrafluoroethylene sealing rings. Background Art

[0002] Polytetrafluoroethylene, commonly known as "the king of plastics", is a high-molecular compound polymerized from tetrafluoroethylene. It has excellent chemical stability, corrosion resistance, sealing performance, high lubricity and non-stickiness, electrical insulation, and good anti-aging endurance. As an engineering plastic, it can be made into polytetrafluoroethylene sealing rings, rods, tapes, plates, films, etc.

[0003] The general method for manufacturing polytetrafluoroethylene sealing rings is the molding method. The specific molding method is as follows: Add powdered (compression molding powder), granular or fibrous plastic raw materials into a molding die. Under pressure, fill the die, close the die and apply pressure to make it form and cure, and then obtain a polytetrafluoroethylene sealing ring.

[0004] Regarding the related technology above, the end face of the sealing ring formed by molding generally has burrs formed by overflow materials. Existing presses generally lack cutting components, and manual grinding and cutting operations are required on its edges, resulting in low efficiency and large human consumption. Utility Model Content

[0005] In order to improve the production efficiency of the sealing ring and reduce human consumption, the present application provides a press for manufacturing polytetrafluoroethylene sealing rings.

[0006] The press for manufacturing polytetrafluoroethylene sealing rings provided by the present application adopts the following technical solutions:

[0007] A press for manufacturing polytetrafluoroethylene sealing rings, comprising a frame;

[0008] A molding die for containing raw materials;

[0009] A stamping device, including a hydraulic cylinder. The hydraulic cylinder is arranged on the top of the frame. The hydraulic cylinder is provided with a telescopic rod, and the telescopic rod is connected with a pressing plate. The pressing plate moves along with the telescopic rod and can squeeze the molding die;

[0010] A cutting device, including a cutting tool and a chuck for fixing the sealing ring. The cutting tool is arranged on the frame. The chuck is connected with a sliding component. The sliding component can drive the chuck to move towards or away from the cutting tool. When the chuck moves to a position close to the cutting tool, the chuck drives the sealing ring to rotate, and the cutting tool cuts the sealing ring.

[0011] By adopting the above technical solution, the chuck moves in the direction close to the cutting tool driven by the sliding component. When the chuck moves to a position close to the cutting tool, the chuck starts to work, fixes the sealing ring, and drives it to rotate. At this time, the cutting tool cuts the end face of the rotating sealing ring to remove burrs. The setting of the cutting device enables the sealing ring to be formed without manual edge grinding and cutting operations, reducing labor consumption and improving production efficiency. In addition, when the cutting device cuts the formed sealing ring, the operator can prepare to stamp the next sealing ring, further improving production efficiency.

[0012] Optionally, the cutting device further includes two guiding plates. The two guiding plates are respectively located on both sides of the chuck along the moving track of the chuck. The end of the guiding plate away from the cutting tool is a guiding portion, and the two guiding portions incline towards each other from the end away from the cutting tool to the end close to the cutting tool.

[0013] By adopting the above technical solution, the main function of the guiding plate is to ensure that the sealing ring can maintain the correct position when moving to the position of the cutting tool, improving the accuracy and efficiency of cutting. Through the guidance of the guiding plate, the trouble of manually aligning the end of the sealing ring with the cutting tool is avoided, and cutting mistakes or quality problems caused by inaccurate positions are reduced.

[0014] Optionally, the sliding component includes a sliding block. The sliding block is connected to the chuck. The sliding block is threadedly connected to a screw rod. One end of the screw rod is fixedly connected to a driving member, and the driving member drives the screw rod to rotate to drive the sliding block to move.

[0015] By adopting the above technical solution, the design of the sliding block, the screw rod and the driving member realizes the reliable sliding of the chuck, ensures the accuracy and stability of the movement of the chuck, provides a good foundation for subsequent cutting operations, and improves production efficiency and product quality.

[0016] Optionally, the sliding block is provided with a slider, and the frame is provided with a slide rail. The slider slides in the slide rail in the direction close to or away from the cutting tool.

[0017] By adopting the above technical solution, the slide rail provides a stable and smooth moving path for the sliding block, ensuring that the sliding block and the chuck can accurately and quickly move to the predetermined position, improving the stability and efficiency of the entire production process, and reducing cutting mistakes or quality problems caused by inaccurate positions.

[0018] Optionally, the forming die includes an outer sleeve, an inner sleeve, and an extrusion sleeve. The outer sleeve and the inner sleeve are coaxially arranged, and the inner diameter of the outer sleeve is greater than the outer diameter of the inner sleeve. The outer sleeve and the inner sleeve together form a placement cavity for placing raw materials. The extrusion sleeve can extrude the raw materials in the placement cavity under the action of the pressing plate.

[0019] By adopting the above technical solution, the combined design of the outer sleeve, the inner sleeve, and the extrusion sleeve makes the structure of the die more compact and the operation more convenient. Under the action of the pressing plate, the extrusion sleeve can accurately extrude the raw materials in the placement cavity, enabling the raw materials to form the required sealing ring shape under the constraint of the die, achieving precise positioning and effective extrusion of the raw materials, and thus producing a sealing ring with stable quality and precise shape.

[0020] Optionally, a limiting ring is arranged in the placement cavity. The inner side wall of the limiting ring abuts against the outer side wall of the inner sleeve, and the outer side wall of the limiting ring abuts against the inner side wall of the outer sleeve.

[0021] By adopting the above technical solution, the limiting ring is used to limit the relative position of the outer sleeve and the inner sleeve, ensuring that the two are in the correct position in the placement cavity and achieving precise positioning. This helps to maintain the stability of the outer sleeve and the inner sleeve during the extrusion process, avoiding deviation or deformation, and thus ensuring the accuracy and consistency of the sealing ring forming.

[0022] Optionally, there are two extrusion sleeves. A convex ring is arranged at one end of one of the extrusion sleeves. The inner side wall of the convex ring abuts against the outer side wall of the inner sleeve, and the outer side wall of the convex ring abuts against the inner side wall of the outer sleeve. The end face of the extrusion sleeve provided with the convex ring can abut against both the end faces of the outer sleeve and the inner sleeve.

[0023] By adopting the above technical solution, the convex ring can extrude the raw materials in the placement cavity to make them form. At the same time, the end face of the extrusion sleeve can abut against both the end faces of the outer sleeve and the inner sleeve, thereby providing support for the outer sleeve and the inner sleeve, reducing the possibility of the outer sleeve or the inner sleeve falling off during the extrusion process, and ensuring the stability and reliability of the extrusion process.

[0024] Optionally, the forming die further includes a guiding sleeve. The guiding sleeve is located inside the inner sleeve, and the outer side wall of the guiding sleeve can abut against both the inner side wall of the inner sleeve and the inner side wall of the extrusion sleeve.

[0025] By adopting the above technical solution, the guiding sleeve provides guidance for the sliding of the extrusion sleeve during the extrusion process. This helps to ensure that the extrusion sleeve can move along a predetermined path during the extrusion process, avoiding deviation or misalignment, and thus improving the stability and accuracy of the extrusion process.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] 1. The setting of the cutting device enables the sealing ring not to require manual edge grinding and cutting operations after molding, reducing labor consumption and improving production efficiency. In addition, when the cutting device performs cutting on the molded sealing ring, the operator can prepare to stamp the next sealing ring, further improving production efficiency;

[0028] 2. The main function of the guide plate is to ensure that the sealing ring can maintain the correct position when moving to the cutter position, improving the accuracy and efficiency of cutting. Through the guidance of the guide plate, the trouble of manually aligning the end of the sealing ring with the cutter is avoided, and cutting errors or quality problems caused by inaccurate positions are reduced;

[0029] 3. The combined design of the outer sleeve, inner sleeve and extrusion sleeve makes the structure of the mold more compact and the operation more convenient. Under the action of the pressing plate, the extrusion sleeve can accurately extrude the raw material in the placement cavity, enabling the raw material to form the required shape of the sealing ring under the constraint of the mold, achieving precise positioning and effective extrusion of the raw material, thereby producing a sealing ring with stable quality and precise shape. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a press for manufacturing a polytetrafluoroethylene sealing ring according to an embodiment of the present application.

[0031] Figure 2 is a schematic structural diagram of the cutting device according to an embodiment of the present application.

[0032] Figure 3 is a cross-sectional view of the first assembled state of the molding die according to an embodiment of the present application.

[0033] Figure 4 is a cross-sectional view of the second assembled state of the molding die according to an embodiment of the present application.

[0034] Description of the reference numerals: 1, frame; 11, partition plate; 12, slide rail; 2, molding die; 21, outer sleeve; 22, inner sleeve; 23, placement cavity; 24, extrusion sleeve; 241, first sleeve; 242, second sleeve; 25, limiting ring; 26, guiding sleeve; 3, stamping device; 31, hydraulic cylinder; 32, telescopic rod; 33, pressing plate; 4, cutting device; 41, chuck; 42, cutter; 43, sliding assembly; 431, sliding block; 432, screw; 433, driving member; 44, guide plate; 441, guiding portion; 442, limiting portion. Detailed Description of the Embodiment

[0035] The following further describes the present application in detail with reference to the attached Figures 1-4 drawings.

[0036] In this application, unless otherwise clearly defined and limited, terms such as "install", "connect", "couple", "fix", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0038] The embodiment of this application discloses a press for manufacturing a polytetrafluoroethylene sealing ring. Refer to Figure 1 , a press for manufacturing a polytetrafluoroethylene sealing ring includes a frame 1. A vertical partition plate 11 is fixedly connected inside the frame 1. The partition plate 11 divides the space into a stamping space and a cutting space. The partition plate 11 is provided with a communication window that communicates the stamping space and the cutting space. A forming die 2 is arranged in the stamping space, and a stamping device 3 is installed. A cutting device 4 is installed in the cutting space. The raw material is placed in the forming die 2, and the stamping device 3 extrudes the forming die 2 to stamp the sealing ring into shape. The cutting device 4 cuts off the stroke edge of the end face of the stamped sealing ring. The setting of the cutting device 4 reduces the labor consumption and improves the production efficiency of the sealing ring.

[0039] Refer to Figure 2, the cutting device 4 includes two cutting tools 42 and a chuck 41 for fixing the sealing ring. Both cutting tools 42 are fixedly connected to the frame 1 at a position away from the stamping device 3, and the two cutting tools 42 respectively perform trimming on both ends of the sealing ring. The chuck 41 is connected to a sliding component 43. The sliding component 43 includes a sliding block 431. The frame 1 is fixedly connected with a slide rail 12 corresponding to the position of the sliding block 431. One side of the sliding block 431 is connected to the chuck 41 through a connecting rod. A slider is fixedly connected to the side of the sliding block 431 away from the chuck 41, and the slider slides within the slide rail 12. The sliding block 431 is threadedly connected to a horizontally arranged screw rod 432. The screw rod 432 is parallel to the slide rail 12. One end of the screw rod 432 is fixedly connected to a driving member 433. The driving member 433 is fixedly connected to the frame 1, and the driving member 433 drives the screw rod 432 to rotate, driving the sliding block 431 and the chuck 41 to move towards or away from the cutting tool 42. In this embodiment, the driving member 433 uses a servo motor, and the chuck 41 uses an electric three-jaw chuck 41. In other embodiments, the driving member 433 can also use other devices for driving the screw rod 432 to rotate.

[0040] Further, referring to Figure 1 and Figure 2 , the cutting device 4 further includes two guiding plates 44. The two guiding plates 44 are fixedly connected to the frame 1 below the chuck 41. The two guiding plates 44 are respectively located on both sides of the chuck 41 along the moving trajectory of the chuck 41. The end of the guiding plate 44 away from the cutting tool 42 is a guiding portion 441, and the direction towards the cutting tool 42 is a limiting portion 442. The two guiding portions 441 are inclined towards each other from the end away from the cutting tool 42 to the end close to the cutting tool 42. The two limiting portions 442 are horizontal, and the distance between them is equal to the length of the sealing ring. The extending positions of the two limiting portions 442 respectively correspond to the positions where the two cutting tools 42 are located.

[0041] The operator sleeves the stamped sealing ring outside the chuck 41, starts the driving member 433, and the driving member 433 drives the sealing ring to move towards the cutting tool 42. During the movement of the sealing ring, it contacts the guiding plate 44 at a position close to the bottom. Under the action of the guiding plate 44, the sealing ring moves to a specific position. When the sealing ring moves to the position of the limiting portion 442, the chuck 41 is started, and the chuck 41 fixes the sealing ring inside the sealing ring. The sealing ring moves towards the cutting tool 42 under the restriction of the limiting portion 442. When the end face of the sealing ring contacts the cutting tool 42, the chuck 41 drives the cutting tool 42 to rotate around the axis, and the two cutting tools 42 remove the burrs on the two end faces of the sealing ring.

[0042] Referring to Figure 1, the stamping device 3 includes a hydraulic cylinder 31 fixedly connected to the top of the frame 1. The hydraulic cylinder 31 is fixedly connected with a telescopic rod 32. The telescopic rod 32 passes through the frame 1 and is connected with a pressing plate 33 in the stamping space. The pressing plate 33 is slidably connected with the frame 1. The pressing plate 33 can move up and down along the frame 1 with the telescopic rod 32 to extrude the forming die 2 and form the sealing ring.

[0043] Referring to Figure 3 and Figure 4 , the forming die 2 includes an outer sleeve 21, an inner sleeve 22 and an extrusion sleeve 24. The outer sleeve 21 and the inner sleeve 22 are of the same height and coaxially arranged. The inner diameter of the outer sleeve 21 is larger than the outer diameter of the inner sleeve 22. The outer sleeve 21 and the inner sleeve 22 together form a placement cavity 23 for placing raw materials.

[0044] Referring to Figure 3 and Figure 4 , a limiting ring 25 is placed in the placement cavity 23. The inner side wall of the limiting ring 25 abuts against the outer side wall of the inner sleeve 22, and the outer side wall of the limiting ring 25 abuts against the inner side wall of the outer sleeve 21. The setting of the limiting ring 25 can limit the relative position of the outer sleeve 21 and the inner sleeve 22 and facilitate the positioning between the outer sleeve 21 and the inner sleeve 22.

[0045] Furthermore, referring to Figure 3 and Figure 4 , there are two limiting rings 25. When raw materials are placed in the placement cavity 23, the two limiting rings 25 are respectively located at both ends in the placement cavity 23 and abut against the raw materials. On the one hand, the two limiting rings 25 can ensure the stability of the outer sleeve 21 and the inner sleeve 22 during the extrusion process. On the other hand, by adjusting the number and height of the limiting rings 25, the height of the formed sealing ring can also be adjusted, improving the flexibility of the device.

[0046] Referring to Figure 4, there are two extrusion sleeves 24, namely the first sleeve 241 and the second sleeve 242 respectively. During assembly, the first sleeve 241 and the second sleeve 242 are located at both ends of the outer sleeve 21 respectively. One end of both the first sleeve 241 and the second sleeve 242 is fixedly connected with a convex ring. When the first sleeve 241, the second sleeve 242, the outer sleeve 21 and the inner sleeve 22 are assembled, the convex ring is placed at the position of the corresponding placement cavity 23 and abuts against the end face of the limiting ring 25. During the extrusion process, the convex ring can enter the placement cavity 23. At this time, the inner side wall of the convex ring abuts against the outer side wall of the inner sleeve 22, and the outer side wall abuts against the inner side wall of the outer sleeve 21. In the assembled state, the inner side walls of the first sleeve 241 and the second sleeve 242 are flush with the inner side wall of the inner sleeve 22, the outer side wall of the first sleeve 241 is flush with the outer side wall of the outer sleeve 21, and the end face of the first sleeve 241 provided with the convex ring can abut against the end faces of both the outer sleeve 21 and the inner sleeve 22. The first sleeve 241 and the second sleeve 242 can extrude the raw material in the placement cavity 23 under the action of the pressing plate 33 to form the sealing ring.

[0047] Further, referring to Figure 3 and Figure 4 , a guide sleeve 26 is further sleeved inside the inner sleeve 22. The guide sleeve 26 is located inside the inner sleeve 22, and the outer side wall of the guide sleeve 26 can abut against the inner side wall of the inner sleeve 22, the inner side wall of the first sleeve 241 and the inner side wall of the second sleeve 242. There are multiple guide sleeves 26, and the multiple guide sleeves 26 have at least two heights. The height value of the guide sleeve 26 of the first height is greater than the height of the first sleeve 241 and less than the sum of the heights of the first sleeve 241 and the outer sleeve 21. The height value of the guide sleeve 26 of the second height is greater than the sum of the heights of the first sleeve 241 and the outer sleeve 21 and less than the sum of the heights of the first sleeve 241, the outer sleeve 21 and the second sleeve 242. The guide sleeve 26 can provide guidance for the sliding of the first sleeve 241 and the second sleeve 242 during the extrusion process, improving the stability during the extrusion process.

[0048] The forming die 2 has two assembled states during use. Referring to Figure 3 , the first assembled state is used for preforming the raw material: the limiting ring 25 is sleeved outside one end of the inner sleeve 22, and then the outer sleeve 21 is sleeved outside the limiting ring 25 to form the placement cavity 23. The placement cavity 23 is filled with the raw material, and another limiting ring 25 is placed above the placement cavity 23 to press the raw material tightly. Then the first sleeve 241 is placed above the outer sleeve 21, the convex ring is aligned with the limiting ring 25, and finally the guide sleeve 26 of the first height is placed inside the inner sleeve 22, and the assembly of the first assembled state is completed. Referring to Figure 4, Assembly state two is used to complete the forming of the sealing ring: On the basis of assembly state one, after taking out the guide sleeve 26, the whole is turned over. At this time, the end of the first sleeve 241 abuts against the workbench surface. Then, place the second sleeve 242 above the outer sleeve 21, align the convex ring with the limit ring 25, and finally place the guide sleeve 26 with the second height inside the inner sleeve 22, thus completing the assembly of assembly state two.

[0049] The implementation principle of a press for manufacturing a polytetrafluoroethylene sealing ring in an embodiment of the present application is as follows: Before stamping, it is first necessary to assemble the forming die 2. First, assemble the forming die 2 according to assembly state one. After the assembly is completed, start the hydraulic cylinder 31. The pressing plate 33 stamps the end of the first sleeve 241. When the convex ring of the first sleeve 241 enters the placement groove and the end of the first sleeve 241 abuts against the end of the outer sleeve 21, the pressing plate 33 is lifted, thus completing the first step of stamping. Then, assemble the forming die 2 according to assembly state two. After the assembly is completed, start the hydraulic cylinder 31 again. The pressing plate 33 stamps the end of the second sleeve 242. When the convex ring of the second sleeve 242 enters the placement groove and the end of the second sleeve 242 abuts against the end of the outer sleeve 21, the pressing plate 33 is lifted, thus completing the stamping and the sealing ring is stamped and formed.

[0050] The operator takes out the stamped sealing ring from the die and slews it outside the chuck 41. Start the driving member 433. The driving member 433 drives the sealing ring to move towards the direction close to the cutting knife 42. When the sealing ring reaches the position of the limiting portion 442, start the chuck 41. The chuck 41 fixes the sealing ring inside the sealing ring and continues to move. When the end face of the sealing ring contacts the cutting knife 42, stop moving. The chuck 41 drives the cutting knife 42 to rotate around the axis, and the two cutting knives 42 cut off the burrs on the two end faces of the sealing ring.

[0051] When the cutting device 4 operates on the stamped sealing ring, the operator can prepare to stamp the next sealing ring.

[0052] The embodiment of the present application has the effects of reducing labor consumption and improving the production efficiency of the sealing ring.

[0053] The above are all the preferred embodiments of the present application. The protection scope of the present application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A press for making polytetrafluoroethylene sealing rings, characterized in that: include: Rack (1); A forming mold (2) for containing raw materials; The punching device (3) comprises a hydraulic cylinder (31), wherein the hydraulic cylinder (31) is arranged on the top of the frame (1), the hydraulic cylinder (31) is provided with a telescopic rod (32), the telescopic rod (32) is connected to a pressing plate (33), and the pressing plate (33) moves with the telescopic rod (32) and is capable of squeezing the forming die (2); The cutting device (4) comprises a cutter (42) and a chuck (41) for fixing a sealing ring, wherein the cutter (42) is arranged on the frame (1), and the chuck (41) is connected to a sliding assembly (43), wherein the sliding assembly (43) can drive the chuck (41) to move towards or away from the cutter (42); when the chuck (41) moves to a position close to the cutter (42), the chuck (41) drives the sealing ring to rotate, and the cutter (42) cuts the sealing ring.

2. A press for making a polytetrafluoroethylene sealing ring according to claim 1, characterized in that: The cutting device (4) further comprises two guide plates (44), the two guide plates (44) being respectively located on two sides of the chuck (41) along the moving track of the chuck (41), the end of the guide plate (44) away from the cutter (42) being a guide portion (441), and the two guide portions (441) being inclined in a direction of approaching each other from the end away from the cutter (42) to the end close to the cutter (42).

3. A press for making polytetrafluoroethylene sealing rings according to claim 1, characterized in that: The sliding assembly (43) comprises a sliding block (431), wherein the sliding block (431) is connected to the chuck (41), the sliding block (431) is threadedly connected to a screw rod (432), one end of the screw rod (432) is fixedly connected to a driving member (433), and the driving member (433) drives the screw rod (432) to rotate and drive the sliding block (431) to move.

4. A press for making a polytetrafluoroethylene sealing ring according to claim 3, characterized in that: The sliding block (431) is provided with a sliding block, and the frame (1) is provided with a sliding rail (12), and the sliding block slides in the sliding rail (12) in a direction approaching or moving away from the cutter (42).

5. A press for making a polytetrafluoroethylene sealing ring according to claim 1, characterized in that: The molding die (2) comprises an outer sleeve (21), an inner sleeve (22) and an extrusion sleeve (24); the outer sleeve (21) and the inner sleeve (22) are coaxially arranged, and the inner diameter of the outer sleeve (21) is larger than the outer diameter of the inner sleeve (22); the outer sleeve (21) and the inner sleeve (22) together form a placement cavity (23) for placing raw materials; and the extrusion sleeve (24) can extrude the raw materials in the placement cavity (23) under the action of the pressing plate (33).

6. A press for making polytetrafluoroethylene sealing rings according to claim 5, characterized in that: A limiting ring (25) is arranged in the placement cavity (23), the inner side wall of the limiting ring (25) abuts against the outer side wall of the inner sleeve (22), and the outer side wall of the limiting ring (25) abuts against the inner side wall of the outer sleeve (21).

7. A press for making polytetrafluoroethylene sealing rings according to claim 5, characterized in that: Two extrusion sleeves (24) are provided, one end of one of the extrusion sleeves (24) is provided with a convex ring, the inner side wall of the convex ring abuts against the outer side wall of the inner sleeve (22), and the outer side wall of the convex ring abuts against the inner side wall of the outer sleeve (21); the end face of the extrusion sleeve (24) provided with the convex ring can abut against the end faces of both the outer sleeve (21) and the inner sleeve (22).

8. A press for making polytetrafluoroethylene sealing rings according to claim 5, characterized in that: The molding die (2) further comprises a guide sleeve (26), wherein the guide sleeve (26) is located inside the inner sleeve (22), and the outer side wall of the guide sleeve (26) can abut against the inner side wall of the inner sleeve (22) and the inner side wall of the extrusion sleeve (24).

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