A connector with an anti-slip external thread structure and its method

Abstract

This invention discloses a connector and method with an anti-slip external thread structure, relating to the field of pipe fitting technology. It solves the problems of insufficient tightness and poor sealing of PTFE tape wound around the external thread structure in existing technologies. It has the beneficial effects of improving the tightness of the PTFE tape and preventing slippage during winding. The specific solution is as follows: A connector with an anti-slip external thread structure is provided on one side of the connector. A straight-knurled structure is provided along the circumferential direction of the external thread structure to enhance mechanical interlocking force and avoid damage to the PTFE tape wound around the external thread structure. The straight-knurled structure is arranged along the axial direction of the external thread, and the knurling is located on the helix of the external thread structure. The knurling pattern is arranged along the axial direction of the connector. The length of the straight-knurled structure is less than the length of the external thread structure, and the depth of the straight-knurled structure is less than the protrusion depth of the helix in the external thread structure.

Description

Technical Field

[0001] This invention relates to the field of pipe fitting technology, and in particular to a fitting and method having an anti-slip external thread structure. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In pipeline connections, such as natural gas pipeline connections, traditional pipe joints feature threaded structures to connect to other pipelines. Currently, the external thread structure is typically a smooth helical surface. Considering natural gas pipelines or other pipelines, to ensure the sealing of the connection, existing technology involves wrapping PTFE tape (polytetrafluoroethylene sealing tape) around the external thread structure of the joint. The PTFE tape is wrapped multiple times along the external thread structure. However, currently, when PTFE tape is wrapped around the joint, the following problems usually exist: Because the external thread structure is a smooth helical surface, the friction between the PTFE tape and the external thread structure is low, resulting in poor tightness of the PTFE tape winding. Moreover, the lack of mechanical interlocking structure between the PTFE tape and the external thread structure leads to weak overall vibration resistance and temperature difference resistance. After a period of use, the sealing performance often deteriorates, and sealing failure occurs. The leakage rate after PTFE tape is wrapped at the external thread of the joint is about 15%-20%, which is difficult to meet the long-term sealing requirements of gas, fire protection and other pipeline systems. The PTFE tape comes into direct contact with the smooth external thread structure, which can easily damage the PTFE tape and destroy the sealing layer. Teflon tape often slips during winding, which hinders rapid winding and makes the winding process highly dependent on the operator's technique, making it difficult for non-professionals to guarantee quality. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a connector with an anti-slip external thread structure, which can improve the tightness of the circumferential PTFE tape winding of the external thread structure, improve the sealing of the pipeline, generate frictional constraint on the PTFE tape, and play an anti-slip role.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: A connector with an anti-slip external thread structure is provided. One side of the connector has an external thread structure, and a knurled structure is provided circumferentially along the external thread structure to enhance mechanical engagement and prevent damage to the PTFE tape wrapped around the external thread structure. The knurled structure is arranged along the axial direction of the external thread and includes multiple knurling points. The knurling of the knurled structure is located on the helix of the external thread structure. The knurling pattern is arranged along the axial direction of the connector. The length of the knurled structure is less than the length of the external thread structure, and the depth of the knurled structure is less than the protrusion depth of the helix in the external thread structure. Gaps are left between the two ends of the knurled structure and the limiting part of the connector and the end of the external thread structure, respectively, so that the PTFE tape can completely cover the knurled structure.

[0006] As described above, a connector with an anti-slip external thread structure, wherein the knurling of the straight knurling structure is evenly distributed on the external thread structure; Along the plane containing the major diameter of the external thread structure, the cross-section of the knurling in the straight-knurled structure is triangular.

[0007] As described above, a connector with an anti-slip external thread structure has knurled knurling that spreads out along the circumferential direction of the connector, with an opening angle of 80°-96°.

[0008] As described above, a connector with an anti-slip external thread structure has a knurling opening angle of 90° in the straight knurling structure.

[0009] As described above, a connector with an anti-slip external thread structure has multiple rows and columns of knurled knurling along the external thread structure. Each row of knurling in the knurled knurling structure is located on the major diameter of the external thread, and each column of knurling is arranged along the axial direction of the external thread structure, so that the knurling pattern intersects the thread helix direction at approximately 90°, forming a bidirectional axial and circumferential frictional constraint on the raw material strip. Along the axial direction of the external thread structure, the angle between two adjacent lines in the knurled knurling structure is 8°-13°.

[0010] As described above, in a connector with an anti-slip external thread structure, the angle between two adjacent lines in the straight knurled structure is 10° along the axial direction of the external thread structure.

[0011] As described above, in a connector with an anti-slip external thread structure, the depth of the knurling in the straight knurling structure is 1 / 12 to 1 / 9 of the protrusion depth of the helix. In a straight-knurled structure, the knurling depth is 0.1mm~0.3mm, and in an external thread structure, the distance between two adjacent knurls in the same spiral plane is 2mm~3mm.

[0012] As described above, a connector with an anti-slip external thread structure includes a tube body, a circumferentially arranged protrusion to form the limiting portion, the external thread structure being located on at least one side of the protrusion, one end of the knurled structure being spaced apart from the protrusion, and the other end of the knurled structure being spaced apart from one end of the external thread structure of the tube body.

[0013] As described above, a connector with an anti-slip external thread structure has a PTFE tape wound circumferentially around the external thread structure, the width of which covers the knurled structure.

[0014] Secondly, the present invention also provides a method for manufacturing a connector with an anti-slip external thread structure, comprising the following: An external thread structure is machined on one side of the connector; The knurled structure is set along the axial direction of the external thread. The knurling of the knurled structure is located on the helix of the external thread structure. The knurling pattern of the knurled structure is set along the axial direction of the joint. The length of the knurled structure is less than the length of the external thread structure. The depth of the knurled structure is less than the protrusion depth of the helix in the external thread structure. Gaps are left between the two ends of the knurled structure and the limiting part of the joint and the end of the external thread structure, respectively, so that the PTFE tape can completely cover the knurled structure.

[0015] The beneficial effects of the present invention are as follows: 1) The connector provided by the present invention has a straight knurled structure at the external thread structure. The knurling of the straight knurled structure is located on the helix of the external thread structure. The knurling pattern of the straight knurled structure is set along the axial direction of the connector. When the PTFE tape is wound at the external thread structure, the knurling pattern of the straight knurled structure contacts the PTFE tape, which effectively enhances the mechanical interlocking force, avoids slippage during PTFE tape winding, and improves the winding speed. The straight-knurled structure creates a convex-concave interlocking seal at the external thread. When combined with PTFE tape wrapped around the external thread, this forms a continuous, gapless sealing layer on the thread surface, significantly improving its density. This increases the tightness of the PTFE tape wrapping by over 40%, reducing the joint leakage rate from the traditional 15%~20% to below 1%, fully meeting the sealing requirements of medium- and high-pressure pipeline systems such as gas and fire protection systems. Furthermore, the constraint of the straight-knurled pattern enhances the sealing layer's resistance to vibration and temperature differences by over 50%. Even after long-term service, it effectively resists the decline in sealing performance caused by thread loosening, extending the sealing life to 1.5~2 times that of traditional products.

[0016] 2) In this invention, the straight knurled structure is opened at the external thread structure, forming a reliable anti-slip structure. The anti-slip structure reduces the dependence on the operation method of wrapping raw material tape. Even non-professionals can avoid slipping and rework, ensuring the consistency of sealing quality. At the same time, the wrapping time is shortened by 30% to 50%, significantly improving the construction error tolerance rate.

[0017] 3) In this invention, the opening angle of the knurling in the straight-knurled structure is reasonably set to achieve uniform fit of the PTFE tape to the entire thread, enhance the vibration resistance of the sealing layer, effectively resist the axial and circumferential displacement of the PTFE tape, and prevent the sealing layer from failing due to loosening; the interval angle between adjacent knurling is reasonably set to ensure the formation of a toothed structure at the external thread structure, enhance the mechanical interlocking force of the straight-knurled structure, and avoid damage to the PTFE tape; the depth of knurling is reasonably controlled to adapt to the embedding requirements of the PTFE tape, so that the PTFE tape and the thread surface form a tight "concave-convex meshing" structure, without affecting the nominal size and strength of the thread.

[0018] 4) The present invention rationally sets the knurling depth, knurling opening angle and the angle between two adjacent knurlings in the straight knurling structure. It is designed by comprehensively considering the structural strength of the joint, the improvement of friction, the compatibility of the PTFE tape and the guarantee of thread performance. It can solve the pain point of traditional threaded PTFE tape wrapping and slipping, while taking into account the sealing connection reliability and processing economy of the joint, and ensuring the structural strength of the joint. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a schematic diagram of a connector with an anti-slip external thread structure according to one or more embodiments of the present invention. Figure 1 .

[0021] Figure 2 This is a schematic diagram of a connector with an anti-slip external thread structure according to one or more embodiments of the present invention. Figure 2 .

[0022] Figure 3 This is a cross-sectional view of a connector component with an anti-slip external thread structure according to one or more embodiments of the present invention.

[0023] Figure 4 This is a schematic diagram of the knurling opening angle in a joint with an anti-slip external thread structure according to one or more embodiments of the present invention.

[0024] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0025] Among them: 1. tube body, 2. protrusion, 3. external thread structure, 4. straight knurled structure, 5. knurling. Detailed Implementation

[0026] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, the existing technology has poor joint material tape tightness and slippage during winding. In order to solve the above technical problems, the present invention proposes a joint with an anti-slip external thread structure.

[0028] Example 1 In a typical embodiment of the present invention, reference is made to Figure 1 and Figure 2 As shown, a connector with an anti-slip external thread structure is provided on one side of the connector. An external thread structure 3 is provided on one side of the connector. A straight knurled structure 4 is provided along the circumferential direction of the external thread structure 3, so that a concave-convex interlocking sealing interface is formed at the external thread structure to enhance the mechanical interlocking force and avoid damage to the PTFE tape wrapped around the external thread structure 3. The straight knurled structure 4 is provided along the axial direction of the external thread. The knurling 5 of the straight knurled structure 4 is located on the helix of the external thread structure 3. The pattern of the straight knurled structure 4 (multiple knurlings in the same axial direction form a pattern) is provided along the axial direction of the connector. The length of the straight knurled structure 4 is less than the length of the external thread structure 3. The depth of the straight knurled structure 4 is less than the protrusion depth of the helix in the external thread structure 3. Gaps are left between the two ends of the straight knurled structure and the limiting part (protrusion) of the connector and the end of the external thread structure, respectively, so that the PTFE tape can completely cover the straight knurled structure.

[0029] In this embodiment, reference Figure 2 and Figure 3As shown, the connector includes a pipe body 1 with a circumferentially arranged protrusion 2. The protrusion 2 is located in the middle of the pipe body 1 or near one end. The outer diameter of the protrusion 2 is larger than the outer diameter of the pipe body 1. A stepped structure is formed between the protrusion 2 and the pipe body 1. An external thread structure 3 is located on at least one side of the protrusion 2. PTFE tape is wrapped circumferentially around the external thread structure 3 to enhance the sealing of the pipe connection. The width of the PTFE tape covers the knurled structure 4. One end of the knurled structure 4 is spaced apart from the protrusion 2, and the other end of the knurled structure 4 is spaced apart from one end of the external thread structure 3 of the pipe body. This ensures that the length of the knurled structure 4 at the external thread structure 3 is less than the wrapping width of the PTFE tape, i.e., there are gaps between the two ends of the knurling and the protrusion and the thread end, respectively, to ensure that the PTFE tape completely covers the knurled area.

[0030] The connector provided in this embodiment features a straight-knurled structure 4 at the external thread structure 3. The knurling 5 of the straight-knurled structure 4 is located on the helix of the external thread structure 3. The knurling pattern of the straight-knurled structure 4 is set along the axial direction of the connector. When the knurling pattern of the straight-knurled structure comes into contact with the PTFE tape, it can achieve an interlocking effect, increasing the tightness of the PTFE tape winding by more than 40%. Combined with the uniform winding of the PTFE tape, a continuous and gapless sealing layer can be formed on the surface of the external thread, reducing the joint leakage rate from the traditional 15%~20% to below 1%, fully meeting the sealing requirements of medium and high pressure pipeline systems such as gas and fire protection. Moreover, the knurling pattern of the straight-knurled structure 4 is located at the external thread structure 3, forming a concave-convex interlocking structure at the structural component. When the PTFE tape is wound around the external thread structure 3, a tight anti-slip structure is formed, which can effectively reduce the dependence on the PTFE tape winding method. Even non-professionals can avoid slippage and rework, ensuring the consistency of sealing quality, while shortening the winding time by 30%~50%.

[0031] In this embodiment, the knurling of the straight-knurled structure is evenly distributed on the external thread structure; along the plane where the major diameter of the external thread structure is located, the cross section of the knurling of the straight-knurled structure is triangular, which is convenient for processing and will not affect the connection capability of the external thread structure.

[0032] It should be noted that along the external thread structure, the knurling of the straight knurling structure has multiple rows and columns. Each row of knurling in the straight knurling structure is located on the major diameter of the external thread, and each column of knurling is set along the axial direction of the external thread structure. The knurling of each column forms the pattern of the straight knurling structure, so that the knurling pattern intersects the thread helix direction at nearly 90°, forming a bidirectional frictional constraint on the raw material strip in both axial and circumferential directions, which fully ensures the friction between the external thread structure and the raw material strip.

[0033] It needs to be explained that the opening angle of a single knurl 5 in the straight-knurled structure 4 (along the plane of the spiral line of the external thread) is 80°-96°. Specifically, the opening angle of knurl 5 in the straight-knurled structure 4 is 90°, which can ensure the uniformity of the PTFE tape winding and the adaptability to working conditions, and achieve uniform fit of the PTFE tape throughout the thread: the orthogonally distributed straight-knurled structure spans the tooth peaks and valleys of the external thread structure 3. During the winding process of the PTFE tape, regardless of the winding direction, the knurling can form a uniform frictional constraint on the PTFE tape, avoiding the phenomenon of local winding being too loose or too tight, and ensuring that the density of the sealing layer is consistent throughout the entire thread length; enhancing the vibration resistance of the sealing layer: the 80°-96° orthogonal knurling and the spiral direction of the thread form a "cross constraint" structure, which can effectively resist the axial and circumferential displacement of the PTFE tape under complex working conditions such as vibration and temperature difference changes, preventing the sealing layer from failing due to loosening and extending the sealing life.

[0034] Specifically, the knurled structure 4 is located on the major diameter of the external thread, along the axial direction of the external thread structure 3. The angle between two adjacent lines in the knurled structure 4 is 8°-13°. In some examples, the angle between two adjacent lines in the knurled structure is 10°. The 8°-13° design balances the protective biting force and the integrity of the PTFE tape. The 8°-13° acute angle pattern is the optimal choice to balance the "anti-slip effect" and "PTFE tape protection," mainly in two aspects: Enhanced mechanical interlocking force: The knurling 5, spaced 8°-13° apart, forms a "tooth-like structure" at the external thread structure 3. When the PTFE tape is wound and tightened, the knurling can slightly embed into the fiber layer of the PTFE tape, significantly increasing the static friction between the thread and the PTFE tape, structurally preventing slippage and displacement of the PTFE tape. Avoiding damage to the PTFE tape: If the angle is too large (e.g., >15°), the anti-slip effect of the PTFE tape will significantly decrease during winding and the PTFE tape fibers will be easily cut, leading to damage to the sealing layer. If the angle is too small (e.g., <5°), it will reduce the strength of the external thread structure 3 and increase processing costs. An angle design of 8°-13°, especially 10°, maximizes the anti-slip effect and ensures optimal thread strength without compromising the integrity of the PTFE tape.

[0035] In this embodiment, the knurling depth in the straight-knurled structure is related to the thickness of the raw material strip, specifically 1-3 times the thickness of a single layer of raw material strip; (Reference) Figure 4As shown, the distance between two adjacent knurls 5 (the distance between the center lines of two adjacent knurls 5) in the plane containing the same spiral line of the straight-knurled structure 4 is 2mm~3mm. This effectively avoids the impact on the strength of the external thread structure while ensuring a tight fit between the PTFE tape and the thread surface. The depth of the knurls 5 in the straight-knurled structure 4 is 0.1mm~0.3mm. This depth range of 0.1mm~0.3mm is a precise value considering sealing fit, thread strength, and interchangeability. Its advantages are as follows: Adaptable to the embedding requirements of PTFE tape: The conventional winding thickness of PTFE tape is 0.07mm~0.1mm, and the knurling depth of 0.1~0.3mm can accommodate 1~3 layers of PTFE tape embedding patterns, so that the PTFE tape and the thread surface form a tight "concave-convex interlocking" structure, which significantly improves the density of the sealing layer. The nominal size and strength of the external thread structure 3 are not affected: the knurling depth is strictly controlled within the tolerance range of the major diameter of the thread, which will not change the nominal diameter of the joint, ensuring that the anti-slip joint can be seamlessly connected with traditional pipe fittings without adjusting the pipeline system; at the same time, the shallow knurling will not damage the base structure of the thread, avoid the decrease in thread strength due to processing, and meet the load-bearing requirements of the high-pressure pipeline system. Prevent overfilling of PTFE tape: If the depth exceeds 0.3mm, the amount of PTFE tape embedded is too large, which can easily lead to excessive resistance when the threads are screwed on, or even cause the PTFE tape to be squeezed out; if the depth is less than 0.1mm, the texture is too shallow and cannot form an effective anti-slip effect.

[0036] The connector provided in this embodiment innovatively incorporates a knurled structure 4 circumferentially machined on the external thread structure 3. During the winding of the PTFE tape, the knurled structure 4 provides an interlocking effect, enhancing the friction between the PTFE tape and the external thread structure, preventing slippage during PTFE tape winding, and shortening the PTFE tape winding time by 30%-50%, effectively improving construction efficiency and reducing reliance on technical personnel, allowing even non-professionals to operate it. After the PTFE tape is wound, the knurled structure 4 effectively engages the PTFE tape, improving the winding tightness and ensuring the connector's sealing performance. Testing shows that after a period of use, the leakage rate of the connector is reduced to below 1%, and its service life is extended.

[0037] The rational setting of the depth of knurling 5, the opening angle of knurling 5, and the angle between adjacent knurling lines in the straight-knurled knurled structure is a comprehensive design that improves friction, adapts to PTFE tape, and ensures thread performance. It not only solves the problem of slippage and winding of traditional threaded PTFE tape, but also takes into account the reliability of the joint's sealing connection and the economy of processing. The setting of the straight-knurled knurled structure creates a concave-convex interlocking sealing structure at the external thread structure and the constraint effect of the 90° orthogonal knurling lines, which effectively improves the vibration resistance of the sealing layer. Because of the better sealing performance, the temperature difference resistance of the joint is improved by more than 50%.

[0038] Example 2 This embodiment provides a method for manufacturing a connector with an anti-slip external thread structure, including the following: 3. An external thread structure is machined on one side of the connector; A knurled structure 4 is machined circumferentially along the external thread structure 3. The knurled structure 4 is set along the axial direction of the external thread. The knurling 5 of the knurled structure 4 is located on the helix of the external thread structure 3. The knurling pattern of the knurled structure 4 is set along the axial direction of the joint. The knurled structure 4 is evenly distributed at the external thread structure 3. The length of the knurled structure 4 is less than the length of the external thread structure 3. The depth of the knurled structure 4 is less than the protrusion depth of the helix in the external thread structure 3 (the depth of the thread). Gaps are left between the two ends of the straight knurled structure and the protrusion of the connector and the end of the external thread structure so that the PTFE tape can completely cover the straight knurled structure. During the processing of the knurled structure, the knurling 5 of the knurled structure is arranged in multiple rows and columns. Each row of knurling 5 in the knurled structure is located on the major diameter of the external thread. The knurling of each column is arranged along the axial direction of the external thread structure. Each column of knurling 5 forms the pattern of the knurled structure. The depth of the knurling 5 in the knurled structure 4 is 0.1mm~0.3mm, which makes the knurling adapt to the embedding depth of the PTFE tape and does not affect the nominal size and strength of the thread. Along the plane of the spiral line of the external thread, the opening angle of a single knurling 5 in the knurled structure 4 (along the plane of the spiral line of the external thread) is 80°-96°. Along the axial direction of the external thread structure 3, the angle between two adjacent patterns in the knurled structure 4 is 8°-13°.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A connector with an anti-slip external thread structure, characterized in that, One side of the connector has an external thread structure, and a straight-knurled structure is provided along the circumferential direction of the external thread structure to enhance mechanical interlocking force and avoid damage to the PTFE tape wrapped around the external thread structure. The straight-knurled structure is set along the axial direction of the external thread and includes multiple knurlings. The knurlings of the straight-knurled structure are located on the helix of the external thread structure. The knurling pattern of the straight-knurled structure is set along the axial direction of the connector. The length of the straight-knurled structure is less than the length of the external thread structure, and the depth of the straight-knurled structure is less than the protrusion depth of the helix in the external thread structure. Gaps are left between the two ends of the straight-knurled structure and the limiting part of the connector and the end of the external thread structure, respectively, so that the PTFE tape can completely cover the straight-knurled structure.

2. A connector with an anti-slip external thread structure according to claim 1, characterized in that, The knurling of the straight knurling structure is evenly distributed on the external thread structure. Along the plane containing the major diameter of the external thread structure, the cross-section of the knurling in the straight-knurled structure is triangular.

3. A connector with an anti-slip external thread structure according to claim 1, characterized in that, In the knurled structure, the knurling opens along the circumferential direction of the joint, and the opening angle of the knurling is 80°-96°.

4. A connector with an anti-slip external thread structure according to claim 3, characterized in that, The knurling opening angle in the straight knurling structure is 90°.

5. A connector with an anti-slip external thread structure according to claim 1, characterized in that, Along the external thread structure, the knurling of the straight knurling structure has multiple rows and columns. Each row of knurling in the straight knurling structure is located on the major diameter of the external thread. Each column of knurling is arranged along the axial direction of the external thread structure, so that the knurling pattern intersects the helical direction of the thread at nearly 90°, forming a bidirectional frictional constraint on the raw material strip in both axial and circumferential directions. Along the axial direction of the external thread structure, the angle between two adjacent lines in the straight knurling structure is 8°-13°.

6. A connector with an anti-slip external thread structure according to claim 5, characterized in that, Along the axial direction of the external thread structure, the angle between two adjacent stripes in the straight knurled structure is 10°.

7. A connector with an anti-slip external thread structure according to claim 1, characterized in that, The depth of the knurling in the knurled structure is 1 / 12 to 1 / 9 of the protruding depth of the spiral line; In a straight-knurled structure, the knurling depth is 0.1mm~0.3mm, and in an external thread structure, the distance between two adjacent knurls in the same spiral plane is 2mm~3mm.

8. A connector with an anti-slip external thread structure according to claim 1, characterized in that, The connector includes a tube body with a circumferentially arranged protrusion to form the limiting portion. The external thread structure is located on at least one side of the protrusion. One end of the straight knurled structure is spaced apart from the protrusion, and the other end of the straight knurled structure is spaced apart from one end of the external thread structure of the tube body.

9. A connector with an anti-slip external thread structure according to claim 1, characterized in that, A PTFE tape is wound circumferentially around the external thread structure, and the width of the PTFE tape covers the straight knurled structure.

10. A method for manufacturing a connector with an anti-slip external thread structure according to any one of claims 1-9, characterized in that, Includes the following: An external thread structure is machined on one side of the connector; A straight-knurled structure is machined circumferentially along the external thread structure. The straight-knurled structure is set along the axial direction of the external thread. The knurling of the straight-knurled structure is located on the helix of the external thread structure. The knurling pattern of the straight-knurled structure is set along the axial direction of the joint. The length of the straight-knurled structure is less than the length of the external thread structure. The depth of the straight-knurled structure is less than the protrusion depth of the helix in the external thread structure. Gaps are left between the two ends of the straight-knurled structure and the limiting part of the joint and the end of the external thread structure, respectively, so that the PTFE tape can completely cover the straight-knurled structure.

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