Large-drift-diameter polytetrafluoroethylene corrugated pipe

Abstract

The invention relates to the technical field of corrugated pipes, in particular to a large-drift-diameter polytetrafluoroethylene corrugated pipe which comprises a multi-layer composite pipe fitting and a connector buckling and pressing module. The multi-layer composite pipe fitting sequentially comprises a woven protective layer used for protection, a supporting reinforcing layer used for reinforcing supporting and a conductive composite layer on the inner side from outside to inside. The connector buckling and pressing module is arranged at the pipe end, a buckling and pressing connector of the connector buckling and pressing module is located between the woven protective layer and the supporting reinforcing layer, the woven protective layer is sleeved with the buckling and pressing shell, and a fixed filling layer is arranged between the buckling and pressing connector and the conductive composite layer. Through the multi-layer composite structure, the conductivity is ensured, and meanwhile, the defects that a traditional single-layer modified material is poor in flexibility and prone to cracking are effectively overcome; the unique buckling and pressing joint arrangement mode is matched with the fixed filling layer, so that thermal stress caused by a thermal flanging process is eliminated, mechanical constraint on radial expansion of the corrugated pipe is realized, the anti-fatigue performance of the polytetrafluoroethylene corrugated pipe is remarkably improved, and the service life of the polytetrafluoroethylene corrugated pipe is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of corrugated pipe technology, and more particularly to a large-diameter polytetrafluoroethylene corrugated pipe. Background Technology

[0002] Polytetrafluoroethylene (PTFE) corrugated pipes have advantages such as large flow area, resistance to high and low temperatures, fatigue resistance, and good flexibility. They are used to connect fuel tanks and fuel pipelines. Their main function is to transfer fuel, reduce pipeline installation stress, achieve flexible pipeline connection, and also have displacement compensation and anti-static functions. They are widely used in fuel transportation systems in aviation, aerospace, petrochemical and other industries.

[0003] Existing large-diameter corrugated hoses use a single-layer black conductive modified composite material inner tube, with end-face sealing achieved through hot flanging and pull-out prevented by a crimping structure. However, carbon black conductive particles are added to the polytetrafluoroethylene (PTFE) inner tube to achieve anti-static properties, which reduces its flexibility and makes it prone to cracking. Furthermore, the thermal stress generated by the secondary hot flanging process further reduces the hose's lifespan. In addition, for ease of assembly, the inner diameter of the connector is usually larger than the outer diameter of the corrugated tube crest; under internal pressure, the radial expansion of the inner tube lacks restraint, which also easily leads to cracking.

[0004] Based on the above-mentioned technical problems, the present invention proposes a large-diameter polytetrafluoroethylene corrugated pipe. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a large-diameter polytetrafluoroethylene corrugated pipe to solve the above-mentioned technical problems.

[0006] The present invention is achieved through the following technical solution: a large-diameter polytetrafluoroethylene corrugated pipe, comprising multi-layer composite pipe fittings and a joint crimping module; The multi-layer composite pipe fitting includes, from the outside to the inside, a braided protective layer for protection, a support reinforcing layer for reinforcement, and an inner conductive composite layer. The connector crimping module is located at the end of the multi-layer composite pipe fitting. The connector crimping module includes a crimping connector and a crimping shell for fastening. The crimping connector is located between the braided protective layer and the supporting reinforcement layer. The crimping shell is located on the outside of the braided protective layer. The crimping connector is fixedly connected to the supporting reinforcement layer, and a fixed filling layer is provided between the crimping connector and the conductive composite layer.

[0007] Furthermore, the conductive composite layer is a spiral double-layer composite pipe with a thickness of 2.5 mm. Both ends of the conductive composite layer are straight cylindrical sections, and the ends of the conductive composite layer are set to be outwardly flared.

[0008] Furthermore, the conductive composite layer includes an outer protective layer and an inner conductive layer, and the thickness ratio of the protective layer to the conductive layer is 22:3.

[0009] Furthermore, the supporting reinforcement layer is a spiral reinforcing rib, and the supporting reinforcement layer is disposed at the bottom of the spiral groove on the surface of the conductive composite layer, and the pitch of the supporting reinforcement layer and the conductive composite layer is equal.

[0010] Furthermore, the braided protective layer is disposed on the outermost layer of the pipe fitting. The braided protective layer is woven from steel wire with a diameter of 0.3 mm and is bonded to the surface of the conductive composite layer.

[0011] Furthermore, the end of the snap-fit ​​housing is fitted to the outer wall of the snap-fit ​​connector, and the snap-fit ​​housing is longer than the snap-fit ​​connector. The bottom of the snap-fit ​​housing is tightly fitted to the conductive composite layer.

[0012] Furthermore, the crimping connector includes a filling section and a crimping section. The filling section is provided with a welding hole for connecting with the support reinforcement layer. The welding hole is a through hole inclined along the diameter direction of the crimping connector. The crimping connector is fixedly connected to the support reinforcement layer through the welding hole. The filling section is provided with an injection hole. The injection hole is located at the intersection of the filling section and the crimping section, and the injection hole is a through hole.

[0013] Furthermore, the inner diameter of the filling section is smaller than the inner diameter of the crimping section, and the filling section is in contact with the straight cylindrical section of the conductive composite layer.

[0014] Furthermore, the fixed filling layer is disposed inside the filling section of the crimping connector, and the fixed filling layer is fixedly connected to the crimping connector, the support reinforcement layer and the conductive composite layer.

[0015] Furthermore, a flange is provided on the outer side of the snap-fit ​​housing, and an electrostatic powder coating is provided on the end face of the flange.

[0016] The beneficial effects of this invention are as follows: A large-diameter polytetrafluoroethylene (PTFE) corrugated pipe includes a multi-layer composite pipe fitting and a crimping module. The multi-layer composite pipe fitting, from the outside to the inside, includes a braided protective layer for protection, a support reinforcing layer for reinforcement, and an inner conductive composite layer. By adopting a multi-layer composite pipe fitting structure composed of a conductive composite layer, a support reinforcing layer, and a braided protective layer, conductivity is ensured while effectively dispersing stress, significantly improving the pipe's flexibility and fatigue life, and avoiding cracking tendencies caused by material modification. By placing the crimping joint between the braided protective layer and the support reinforcing layer, and combining it with a fixed filling layer to achieve a tight internal fit and radial restraint, the reliability of the end-face seal is ensured, and the radial expansion of the corrugated pipe under internal pressure is effectively suppressed, fundamentally preventing inner pipe cracking. The overall structure, while maintaining advantages such as large diameter, high flexibility, resistance to high and low temperatures, and antistatic properties, significantly improves the service life and safety stability of the corrugated pipe under long-term alternating pressure. Attached Figure Description

[0017] Figure 1 A schematic diagram of the overall structure of a large-diameter polytetrafluoroethylene corrugated pipe; Figure 2 This is a cross-sectional view of a crimp connector; Figure 3 This is a schematic diagram showing the connection between the crimp connector and the reinforcing rib. Figure 4 This is a cross-sectional view of the welding position between the crimped connector and the reinforcing rib.

[0018] In the diagram: 1. Flange; 2. Crimped outer shell; 3. Braided protective layer; 4. Crimped connector; 41. Crimped section; 42. Limiting section; 43. Welding hole; 44. Injection hole; 5. Fixed filler layer; 6. Reinforcing rib; 7. Corrugated inner tube. Detailed Implementation

[0019] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1-4 As shown in the figure, this embodiment discloses a large-diameter polytetrafluoroethylene corrugated pipe, which is mainly used between the oil tank and the oil pipeline, and a multi-layer composite pipe fitting and joint crimping module.

[0022] The multi-layer composite pipe fitting includes, from the outside to the inside, a braided protective layer 3 for protection, a support reinforcing layer for reinforcement, and an inner conductive composite layer.

[0023] The connector crimping module is installed at the end of the multi-layer composite pipe fitting, and the connector crimping module is installed between the braided protective layer 3 and the support reinforcement layer. The connector crimping module includes a crimping connector 4 and a crimping housing 2 for fastening. The crimping housing 2 is installed on the outermost side of the braided protective layer 3. The crimping connector 4 is fixedly connected to the support reinforcement layer, and a fixed filling layer 5 is provided between the crimping connector 4 and the conductive composite layer.

[0024] The conductive composite layer is a spiral double-layered corrugated inner tube 7, which includes an outer protective layer and an inner conductive layer. The conductive layer is a modified composite material made of polytetrafluoroethylene (PTFE) with added carbon black, giving the inner layer of the tube conductivity. The outer protective layer is made of pure PTFE, which is resistant to high temperatures and corrosion. The total thickness of the corrugated inner tube 7 is 2.5 mm, with the inner conductive layer having a thickness of 0.3 mm to 0.5 mm. The corrugated inner tube 7 is produced by co-extrusion. First, a straight tube blank is made using an extruder, and then the tube blank is clamped inside and outside a die and heated and pressurized to form a spiral pipe.

[0025] The two ends of the corrugated inner tube 7 are designed as straight cylindrical sections, with the ends of these sections turned outwards. This allows for better mating with the crimp connector 4, enhancing the stability of the connection and effectively preventing loosening or detachment during use. Simultaneously, the spiral structure and specific thickness ratio not only ensure good anti-static performance of the corrugated inner tube 7 but also reduce the impact of conductive carbon black on the physical properties of the polytetrafluoroethylene material, preserving the original tensile strength and other performance indicators of the tube body, and to a certain extent extending the service life of the fitting.

[0026] A supporting reinforcement layer is installed within the spiral groove of the corrugated inner tube 7. This layer consists of spiral reinforcing ribs 6, which are installed at the bottom of the spiral groove by rotating and winding. The pitch of the reinforcing ribs 6 is equal to that of the spiral groove of the corrugated inner tube 7. Furthermore, the reinforcing ribs 6 do not exceed the crest of the corrugated inner tube 7 within the spiral groove. The diameter of the reinforcing ribs 6 is 4mm. These ribs ensure stable support for the pipe fitting in complex operating environments. The reinforcing ribs 6 fit seamlessly with the spiral structure of the corrugated inner tube 7, enhancing the overall structural strength of the pipe fitting. This not only effectively disperses the stress generated when the pipe fitting is subjected to external forces but also provides additional support to the corrugated inner tube 7 when fluid pressure suddenly increases, preventing deformation or damage due to pressure changes. This allows the pipe fitting to maintain stable performance and structural integrity even when subjected to high pressure, high temperature, or frequent fluid impacts.

[0027] A braided protective layer 3 is installed on the outside of the reinforcing rib 6 and the corrugated inner tube 7. The braided protective layer 3 is made of steel wire with a diameter of 0.3mm. It fits tightly against the outside of the corrugated inner tube 7, effectively resisting external physical impacts and wear, further extending the service life of the pipe fitting. During the pipe fitting production process, the braided protective layer 3 is applied to the outside of the corrugated inner tube 7 after the reinforcing rib 6 has been wound. The steel wires of the braided protective layer 3 are cross-woven, giving the large-diameter PTFE corrugated pipe higher strength and toughness, enabling it to better withstand external forces in different directions. Moreover, the tight fit between the braided protective layer 3 and the corrugated inner tube 7 fully utilizes its protective function, ensuring the pressure-bearing and electrical conductivity of the large-diameter pipe body while guaranteeing its service life of 100,000 pressure cycles.

[0028] A crimping module is installed at the end of the pipe fitting. The crimping module includes a crimping connector 4 and a crimping housing 2 for fastening. The crimping housing 2 is installed on the outside of the braided protective layer 3, and the crimping connector 4 is installed between the braided protective layer 3 and the reinforcing rib 6. The crimping connector 4 includes a crimping section 41 and a filling section 42. The crimping section 41 is a straight cylindrical section that contacts the straight cylindrical section at the end of the corrugated inner pipe 7. The inner diameter of the crimping section 41 is the same as the outer diameter of the straight cylindrical section of the corrugated inner pipe 7. To fix the reinforcing rib 6, a welding hole 43 is provided on the filling section 42. The crimping connector 4 is fixed to the reinforcing rib 6 through the welding hole 43. Since the reinforcing rib 6 is spiral-shaped and the spiral direction is along the circumference of the crimping connector 4, in order to ensure that the physical properties of the reinforcing rib are not affected, the welding hole 43 is a through hole inclined along the diameter direction of the crimping connector 4. The end of the reinforcing rib 6 only needs a very small angle of deformation to be inserted into the welding hole 43. After inserting the end of the reinforcing rib 6 into the welding hole 43, the reinforcing rib protruding from the surface of the crimping connector 4 needs to be cut off. Then, the crimping connector 4 and the reinforcing rib 6 are fixed by argon arc welding. After the welding is completed, the braided protective layer 3 of the welded part needs to be restored to the installation position.

[0029] The crimping housing 2 can be made of stainless steel. By compressing and deforming the end of the crimping housing 2, the braided protective layer 3 can be fixedly connected to the crimping connector 4. The length of the crimping housing 2 is longer than that of the crimping connector 4. The bottom of the crimping housing 2 is fitted with the corrugated inner tube 7. By compressing and deforming the crimping housing 2, the braided protective layer 3 can be fixedly connected to the corrugated inner tube 7.

[0030] To eliminate the gap between the corrugated inner tube 7 and the crimping connector 4, an injection hole 44 is provided at the junction of the crimping section 41 and the filling section 42. An appropriate amount of epoxy resin is injected into the gap through the injection hole 44. After the epoxy resin solidifies, a solid fixed filling layer 5 is formed at the filling section 42 of the corrugated inner tube 7 and the crimping connector 4, which provides support for the corrugated inner tube 7 and prevents the pipe from deforming due to excessive pressure inside the pipe.

[0031] After the crimping connector 4 is installed, the straight section of the corrugated inner tube 7 is turned outward by hot flanging, so that the outer wall of the corrugated inner tube 7 fits with the end of the crimping connector 4, and the flanged part that extends beyond the end face of the crimping connector 4 is cut off, thereby forming a complete pipe fitting mating surface.

[0032] A flange 1 is installed on the outside of the crimp connector 4. The flange 1 can be a butt flange. After the flange 1 is installed, electrostatic powder spraying is performed on the end face of the flange 1 and the outward turn of the corrugated inner tube 7 to form a uniform coating. When the large-diameter polytetrafluoroethylene corrugated tube is connected to the components, the sealing of the connection surface is ensured.

[0033] When installing large-diameter PTFE corrugated pipes and fittings, firstly, a braided protective layer 3 of appropriate size is placed on the outside of the corrugated inner tube 7, which has been wrapped with reinforcing ribs 6. Then, the crimping shell 2 is inserted into the corrugated pipe body. The crimping connector 4 is installed between the corrugated inner tube 7 and the braided protective layer 3 at the end of the fitting. The braided protective layer 3 at the welding hole 43 is then removed to expose the crimping connector 4. The position of the crimping connector 4 is adjusted so that the end of the reinforcing rib 6 is inserted into the welding hole 43. The reinforcing rib protruding from the welding hole 43 is then cut off. The reinforcing rib 6 and the crimping connector 4 are then welded. After welding, the weld is ground smooth and the braided protective layer 3 is repositioned. Epoxy resin is then injected into the filling section 42 to fill and support the gaps. After the epoxy resin solidifies, a fixed filling layer 5 is formed between the crimping connector 4 and the corrugated inner tube 7. The crimping shell 2 is then moved to the location of the crimping connector 4, and the braided protective layer 3 is fixedly connected to the crimping connector 4 and the corrugated inner tube 7 by axially pressing the crimping shell 2. Then, the straight section of the corrugated inner tube 7 extending beyond the end face of the crimping connector 4 is heated and turned outward to fit the end of the crimping connector 4. The turned-out portion extending beyond the end face of the crimping connector 4 is then cut off. Finally, a butt flange 1 is installed on the outside of the crimping connector 4. After fixing the flange 1 to the pipe fitting, electrostatic powder coating is applied to the end faces of the flange 1 and the corrugated inner tube 7. The installation of the large-diameter polytetrafluoroethylene corrugated pipe is then completed.

[0034] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A large-diameter polytetrafluoroethylene corrugated pipe, characterized in that, Includes multi-layer composite pipe fittings and connector crimping modules; The multi-layer composite pipe fitting includes, from the outside to the inside, a braided protective layer (3) for protection, a support reinforcing layer for reinforcement, and an inner conductive composite layer. The connector crimping module is located at the end of the multi-layer composite pipe fitting. The connector crimping module includes a crimping connector (4) and a crimping shell (2) for fastening. The crimping connector (4) is located between the braided protective layer (3) and the support reinforcement layer. The crimping shell (2) is located on the outside of the braided protective layer (3). The crimping connector (4) is fixedly connected to the support reinforcement layer. A fixed filling layer (5) is provided between the crimping connector (4) and the conductive composite layer.

2. The large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The conductive composite layer is a spiral double-layer composite pipe with a thickness of 2.5 mm. Both ends of the conductive composite layer are straight cylindrical sections, and the ends of the conductive composite layer are flared outwards.

3. The large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The conductive composite layer includes an outer protective layer and an inner conductive layer, and the thickness ratio of the protective layer to the conductive layer is 22:

3.

4. The large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The supporting reinforcement layer is a spiral reinforcing rib, which is disposed at the bottom of the spiral groove on the surface of the conductive composite layer, and the pitch of the supporting reinforcement layer is equal to that of the conductive composite layer.

5. A large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The braided protective layer (3) is set on the outermost layer of the pipe fitting. The braided protective layer is made of steel wire with a diameter of 0.3 mm and is attached to the surface of the conductive composite layer.

6. A large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The end of the snap-fit ​​housing (2) is attached to the outer wall of the snap-fit ​​connector (4), and the snap-fit ​​housing (2) is longer than the snap-fit ​​connector (4). The bottom of the snap-fit ​​housing (2) is tightly attached to the conductive composite layer.

7. A large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The crimping connector (4) includes a filling section (42) and a crimping section (41). A welding hole (43) for connecting with the support reinforcement layer is provided on the filling section (42). The welding hole (43) is a through hole inclined along the diameter direction of the crimping connector (4). The crimping connector (4) is fixedly connected to the support reinforcement layer through the welding hole (43). An injection hole (44) is provided in the filling section (42). The injection hole (44) is located at the intersection of the filling section (42) and the crimping section (41), and the injection hole (44) is a through hole.

8. A large-diameter polytetrafluoroethylene corrugated pipe according to claim 7, characterized in that, The inner diameter of the filling section (42) is smaller than that of the crimping section (41), and the filling section (42) is in contact with the straight section of the conductive composite layer.

9. A large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, The fixed filling layer (5) is disposed inside the filling section (42) of the crimp connector (4), and the fixed filling layer (5) is fixedly connected to the crimp connector (4), the support reinforcement layer and the conductive composite layer.

10. A large-diameter polytetrafluoroethylene corrugated pipe according to claim 1, characterized in that, A flange is provided on the outside of the snap-fit ​​housing (2), and an electrostatic powder coating is provided on the end face of the flange.

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