Multi-layer PE nano clean pipe and preparation method thereof

Abstract

The invention relates to the technical field of polymer pipes, in particular to a multi-layer PE nano clean pipe and a preparation method thereof.The multi-layer PE nano clean pipe comprises a physical barrier layer and a high-density PE shell and further comprises a lining layer and a buffer layer, the physical barrier layer is sleeved with the lining layer, the buffer layer is sleeved with the buffer layer, the buffer layer is sleeved with the high-density PE shell, and the high-density PE shell is sleeved with the high-density PE shell. A flow guide groove is formed in the inner wall of the physical blocking layer, and a containing groove is formed in the inner wall of the lining layer. Through the flow guide groove, the containing groove and the buffer layer, the cleaning effect can be improved while the inner wall of the pipe is prevented from generating'dead corners' of bacterium breeding, and normal operation of the semiconductor technology is effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of polymer pipe technology, specifically to a multilayer PE nano-clean pipe and its preparation method. Background Technology

[0002] PE pipe, simply put, refers to pipes made of polyethylene plastic. The conduits are usually made of low-density polyethylene, which is widely used because of its good chemical stability, high flexibility and good biocompatibility.

[0003] In urban construction, high-molecular-weight polyethylene (PE) pipes are widely used as protective devices for power cable pipelines. However, underground pipelines are complex and intertwined. During construction, to avoid damaging the road surface, PE pipes need to be pulled, which can lead to damage under friction, thus affecting their protective effect. To address this problem, existing technologies offer relatively good solutions, such as a multi-layer composite PE conduit and its preparation method disclosed in CN117511037A. This conduit includes a wear-resistant outer layer and a reinforced inner layer integrally formed with the wear-resistant outer layer. The wear-resistant outer layer comprises low-entanglement ultra-high molecular weight polyethylene, high-density polyethylene, trimethylolpropane trimethacrylate, tripropylene glycol diacrylate, a catalyst, silicon carbide whiskers, nano-grade bamboo powder, and calcium stearate. The reinforced inner layer comprises high-density polyethylene, low-density polyethylene, polypropylene, a crosslinking agent, rare earth stabilizers, auxiliary stabilizers, and modified graphite oxide nanoparticles, effectively improving the impact resistance and wear resistance of the PE pipe. However, the following defects still exist: Since PE nano-clean tubes are not universal products, in semiconductor high-temperature ultrapure water systems, under high-speed fluid flushing or pressure fluctuations, the inner wall surface of the PE nano-clean tube will expand due to heat and produce wavy wrinkles, thus forming "dead corners" for the growth of nano-impurities and bacteria, which in turn affects the semiconductor process.

[0004] Therefore, in order to solve the above problems, a multilayer PE nano-clean tube and its preparation method are proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a multilayer PE nanotube and its preparation method, solving the problem of bacterial growth "dead zones" on the inner wall of PE nanotubes in semiconductor manufacturing processes, which affects the semiconductor production process. By incorporating a flow guide channel, a receiving channel, and a buffer layer, the deformation direction is guided and buffered when the inner wall of the tube deforms due to temperature differences and fluid kinetic energy. This avoids bacterial growth "dead zones" on the inner wall of the tube while improving the cleaning effect, effectively ensuring the normal operation of the semiconductor process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A multi-layer PE nano-clean tube includes a physical barrier layer and a high-density PE outer shell, as well as an inner liner and a buffer layer. The inner liner is fitted outside the physical barrier layer, the buffer layer is fitted outside the inner liner, and the high-density PE outer shell is fitted outside the buffer layer. The inner wall of the physical barrier layer is provided with a flow guide channel, and the inner wall of the inner liner is provided with a receiving groove. When room temperature ultrapure water flows in the tube, the physical barrier layer is heated and expands into the flow guide channel, which expands into the receiving groove. When high temperature ultrapure water flows in the tube, the flow guide channel expands and adheres to the inner wall of the receiving groove, and the receiving groove transfers the heat of the high temperature ultrapure water to the buffer layer. The buffer layer deforms due to heat and squeezes the outer wall of the receiving groove.

[0007] Preferably, the buffer layer includes a sheath, a spiral reinforcing rib, and an elastic sheet. The buffer layer is sleeved outside the inner lining layer. The outer wall of the inner lining layer has a spiral groove. The spiral reinforcing rib is sleeved between the inner lining layer and the buffer layer and matches the spiral groove. The elastic sheet is disposed on the inner wall of the spiral reinforcing rib and located inside the spiral groove.

[0008] Preferably, the elastic sheet is a shape memory metal sheet, and there are multiple elastic sheets arranged in an array along the spiral direction of the spiral groove. The projection of each elastic sheet along the radial direction of the physical barrier layer is located within the projection of the corresponding receiving groove along the radial direction of the physical barrier layer.

[0009] Preferably, both the guide channel and the receiving channel are arc-shaped channels, and there are multiple guide channels and receiving channels arranged in a circumferential array. The projection of each guide channel along the radial direction of the physical barrier layer is located within the projection of the corresponding receiving channel along the radial direction of the physical barrier layer.

[0010] Preferably, the phase change temperature of the elastic sheet is the temperature conducted to the spiral groove when high-temperature ultrapure water flows at 85°C.

[0011] Preferably, the depth of the receiving groove is one-third to one-half of the opening width, and the opening width of the receiving groove is greater than the opening width of the guide groove.

[0012] Preferably, the elastic sheet is arc-shaped and its two ends are movably sleeved with the inner wall of the spiral reinforcing rib, and the middle part of the elastic sheet is in contact with the bottom of the spiral groove.

[0013] A method for preparing a multilayer PE nanotube cleanroom includes the following steps: S1. Preparation of physical barrier layer: The physical barrier layer is extruded by an extrusion molding machine, and during the extrusion process, guide grooves distributed in a circumferential array are formed on its inner wall by a die. S2. Preparation of inner liner: The inner liner is extruded and coated on the outer wall surface of the physical barrier layer, and a receiving groove corresponding to the radial projection of the guide groove is formed on the inner wall of the inner liner during extrusion. At the same time, a spiral groove is formed on the outer wall of the inner liner. S3. Assemble the buffer layer: The elastic sheet, which is a memory metal sheet, is pre-installed on the inner wall of the spiral reinforcing rib by its two ends being movably sleeved; then, the spiral reinforcing rib with the elastic sheet is wound along the spiral direction and fitted into the spiral groove of the inner liner, so that the middle part of the elastic sheet contacts the bottom of the spiral groove, and then the outer sheath is extruded. S4. Preparation of the outer shell: A high-density PE shell is extruded and coated on the outside of the sheath of the buffer layer, and then shaped after cooling and traction.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By cooperating with the flow guide groove set on the inner wall of the physical barrier layer and the receiving groove on the inner wall of the inner lining layer, space can be reserved for the directional release of the thermal deformation of the physical barrier layer. This prevents the inner wall of the pipe from bulging into the cavity due to minor internal stress. Whether it is room temperature ultrapure water or high temperature ultrapure water, the inner wall can regularly expand and grow outward after being heated, thus always maintaining the smoothness and flatness of the inner wall of the pipe to eliminate the "dead corners" of nano-impurity residue and bacterial growth, and meeting the ultra-high cleanliness requirements of semiconductor process for ultrapure water transportation.

[0015] 2. Through the design of spiral grooves, spiral reinforcing ribs, and elastic sheets, when ultrapure water flows at high speed or water pressure pulsates inside the pipe, the stress caused by the fluid kinetic energy can be effectively guided and dissipated along a continuous spiral trajectory, avoiding local collapse of the pipe wall or interlayer tearing. At the same time, when the internal high temperature causes the inner layer to expand radially outward, the elastic compression generated by the elastic sheet can provide sufficient capacity for the thermal expansion volume transmitted by the inner layer, avoiding the hidden danger of the inner layer material being forced to compress inward due to lack of expansion space, greatly extending the overall fatigue life of the pipe, and thus ensuring the normal operation of the semiconductor process.

[0016] 3. By utilizing the shape memory properties of the elastic sheet, it deforms and changes the squeezing force on the spiral groove when 85℃ high-temperature ultrapure water is introduced, thereby increasing the turbulence of the internal water flow to improve the cleaning effect without dead corners; when the water flow returns to normal temperature, the elastic sheet can undergo a martensitic phase transformation as the temperature drops, instantly unloading the inward squeezing force and returning to a soft state, allowing the inner PE material to naturally shrink back to its original position, ensuring that the pipe maintains extremely high initial dimensional accuracy even after frequent alternation of hot and cold cycles, further ensuring the normal operation of semiconductor processes. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 Enlarged view of part A in the middle section; Figure 3This is a schematic diagram of the connection structure between the physical barrier layer, the inner lining layer, the buffer layer, and the high-density PE shell of the present invention. Figure 4 This is a schematic diagram of the connection structure between the spiral reinforcing rib and the elastic sheet of the present invention.

[0018] In the diagram: 1. Physical barrier layer; 11. Flow guide channel; 2. High-density PE shell; 3. Inner lining layer; 31. Receiving groove; 32. Spiral groove; 4. Buffer layer; 41. Sheath; 42. Spiral reinforcing rib; 43. Elastic sheet. Detailed Implementation

[0019] 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.

[0020] Please see Figures 1 to 4 This invention provides a multilayer PE nano-clean tube and its preparation method, the technical solution of which is as follows: For details, please refer to Figure 1 , Figure 2 and Figure 3 A multi-layer PE nano-clean tube includes a physical barrier layer 1 and a high-density PE outer shell 2, as well as an inner liner layer 3 and a buffer layer 4. The inner liner layer 3 is fitted outside the physical barrier layer 1, the buffer layer 4 is fitted outside the inner liner layer 3, and the high-density PE outer shell 2 is fitted outside the buffer layer 4. The inner wall of the physical barrier layer 1 is provided with a flow guide groove 11, and the inner wall of the inner liner layer 3 is provided with a receiving groove 31. When room temperature ultrapure water flows in the tube, the physical barrier layer 1 is heated and expands into the flow guide groove 11. When the flow guide groove 11 expands, it expands into the receiving groove 31. When high temperature ultrapure water flows in the tube, the flow guide groove 11 expands and adheres to the inner wall of the receiving groove 31. The receiving groove 31 transfers the heat of the high temperature ultrapure water to the buffer layer 4. The buffer layer 4 is heated and deforms, squeezing the outer wall of the receiving groove 31.

[0021] It is known that in semiconductor manufacturing processes, the high-speed flow of ultrapure water inside the pipe causes vibration of the inner wall of the pipe, resulting in local expansion or contraction of the inner wall of the pipe. This causes wavy folds on the inner wall of the pipe, creating dead corners for bacterial growth, which seriously affects the production operation of semiconductor processes. Therefore, this solution is adopted. In semiconductor manufacturing processes, even when conveying ultrapure water at room temperature, the tubing undergoes slight deformation due to basic physical factors such as ambient temperature differences, fluid friction heat generation, and internal water pressure. By creating flow channels 11 on the inner wall of the physical barrier layer 1, space can be reserved for the directional release of this deformation. This prevents the inner wall of the physical barrier layer 1 from bulging into the tube cavity due to minor internal stress, thus maintaining absolute smoothness and flatness inside the tube cavity under room temperature conditions and reducing flow field disturbances caused by minor deformations. Furthermore, when high-temperature ultrapure water is introduced to clean the inner wall of the tubing, the physical barrier layer 1 expands and extends regularly in the direction of the flow channels 11 after being heated, maintaining the overall flatness and smoothness of the inner wall. This effectively prevents the formation of disordered wrinkles, eliminates the potential for nano-impurities and bacterial residues, and effectively ensures the ultra-high cleanliness requirements of the nano-clean tube, thereby guaranteeing the quality of the semiconductor process.

[0022] As one embodiment of the present invention, refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 The buffer layer 4 includes a sheath 41, a spiral reinforcing rib 42, and an elastic sheet 43. The buffer layer 4 is sleeved on the outside of the inner lining layer 3. The outer wall of the inner lining layer 3 has a spiral groove 32. The spiral reinforcing rib 42 is sleeved between the inner lining layer 3 and the buffer layer 4 and matches the spiral groove 32. The elastic sheet 43 is disposed on the inner wall of the spiral reinforcing rib 42 and is located inside the spiral groove 32.

[0023] Under the above conditions, the spiral reinforcing rib 42 located between the inner liner 3 and the buffer layer 4 can reinforce the inner liner 3 from the outside. Simultaneously, in conjunction with the spiral groove 32 on the outer wall of the inner liner 3, the stress generated by the fluid kinetic energy during high-speed flow of ultrapure water inside the pipe is spirally guided and dissipated along the continuous trajectory of the spiral groove 32 and the spiral reinforcing rib 42, effectively extending the overall fatigue life of the multi-layer PE nano-clean pipe. Furthermore, when the high-temperature ultrapure water causes the inner liner 3 and the physical barrier layer 1 to expand radially outward, resulting in the elastic sheet 43 being compressed, the elastic sheet 43 absorbs the thermal expansion volume transmitted from the inner layer through its own elastic compression, providing sufficient capacity for the expansion of the internal material. This prevents the inner wall material from being squeezed into the pipe cavity due to lack of expansion space, thus preventing "wavy wrinkles" and ensuring the smoothness and cleanliness of the inner wall of the pipe. Moreover, during the repositioning process, the elastic sheet 43 can also increase the turbulence of the high-temperature ultrapure water inside the pipe, further preventing the formation of cleaning dead zones and improving the cleaning effect.

[0024] As one embodiment of the present invention, refer to Figure 3 and Figure 4 The elastic sheet 43 is a shape memory metal sheet. Multiple elastic sheets 43 are arrayed along the spiral direction of the spiral groove 32. The projection of each elastic sheet 43 along the radial direction of the physical barrier layer 1 is located within the projection of the corresponding receiving groove 31 along the radial direction of the physical barrier layer 1. The phase change temperature of the elastic sheet 43 is the temperature conducted to the spiral groove 32 when high-temperature ultrapure water flows at 85°C. The elastic sheet 43 is arc-shaped and its two ends are movably sleeved with the inner wall of the spiral reinforcing rib 42. The middle part of the elastic sheet 43 is in contact with the bottom of the spiral groove 32.

[0025] It is known that ordinary elastic components inevitably experience stress decay under long-term alternating heating and cooling and stress. However, due to the superelasticity and bidirectional shape memory effect of shape memory alloys, when the water flow inside the pipe returns to normal temperature, the elastic sheet 43 undergoes a martensitic phase transformation as the temperature drops, instantly "unloading" the inward compressive force and returning to its soft initial state. This allows the inner PE material to naturally shrink back to its original position. By utilizing this dynamic effect of actively pressurizing during thermal expansion and automatically releasing pressure during cold contraction, the pipe maintains its initial dimensional accuracy even after frequent thermal cycles. At the same time, since the temperature of the high-temperature ultrapure water used for cleaning is 80℃-85℃, the shape of the elastic sheet 43 can be indirectly adjusted by adjusting the temperature of the high-temperature ultrapure water during cleaning. This allows the elastic sheet 43 to continuously change the compressive force on the spiral groove 32 during deformation, thereby continuously adjusting the turbulence effect of the ultrapure water used for cleaning inside the pipe and further improving the cleaning effect.

[0026] As one embodiment of the present invention, refer to Figure 1 , Figure 2 and Figure 3 Both the guide channel 11 and the receiving channel 31 are arc-shaped channels. There are multiple guide channels 11 and receiving channels 31 arranged in a circular array. The projection of each guide channel 11 along the radial direction of the physical barrier layer 1 is located within the projection of the corresponding receiving channel 31 along the radial direction of the physical barrier layer 1. The depth of the receiving channel 31 is one-third to one-half of the opening width, and the opening width of the receiving channel 31 is greater than the opening width of the guide channel 11.

[0027] Under the above conditions, after the flow channel 11 expands due to heat, its arc surface can fit with the inner arc surface of the receiving channel 31, thereby reducing the contact thermal resistance. This allows the heat from the high-temperature ultrapure water to be quickly and efficiently conducted to the elastic sheet 43, enabling the elastic sheet 43 to respond quickly. At the same time, each flow channel 11 and the corresponding receiving channel 31 form a "gear spline" interlocking structure, providing effective anti-torsion and anti-peeling capabilities. This ensures that the inner liner 3 has a sufficiently thick and continuous solid skeleton, thus preventing interlayer tearing or local collapse of the tube wall when the inner liner 3 is subjected to severe fluid pulsation, further guaranteeing the normal operation of the semiconductor process.

[0028] A method for preparing a multilayer PE nanotube cleanroom includes the following steps: S1. Preparation of physical barrier layer 1: Extruding physical barrier layer 1 through an extrusion molding machine, and forming guide grooves 11 distributed in a circumferential array on its inner wall through a die during the extrusion process; S2. Preparation of inner liner 3: The inner liner 3 is extruded and coated on the outer wall surface of the physical barrier layer 1, and during extrusion, a receiving groove 31 corresponding to the radial projection of the guide groove 11 is formed on the inner wall of the inner liner 3. At the same time, a spiral groove 32 is formed on the outer wall of the inner liner 3. S3. Assemble the buffer layer 4: The elastic sheet 43, which is a memory metal sheet, is pre-installed on the inner wall of the spiral reinforcing rib 42 with its two ends movably sleeved; then, the spiral reinforcing rib 42 with the elastic sheet 43 is wound along the spiral direction and fitted into the spiral groove 32 of the inner liner layer 3, so that the middle part of the elastic sheet 43 contacts the bottom of the spiral groove 32, and then the outer sheath 41 is extruded. S4. Preparation of the outer shell: A high-density PE outer shell 2 is extruded and coated on the outside of the sheath 41 of the buffer layer 4, and then shaped after cooling and traction.

[0029] Working principle: When transporting room temperature ultrapure water inside the pipe, the physical barrier layer 1 undergoes slight deformation due to physical influences such as ambient temperature difference, fluid friction heat generation, or water pressure inside the pipe. At this time, the physical barrier layer 1 is heated and expands directionally towards the pre-set guide groove 11 on its inner wall. When the guide groove 11 expands, it initially expands into the receiving groove 31 on the inner wall of the inner lining layer 3, preventing the inner wall of the pipe from bulging inward. Under room temperature conditions, it always maintains absolute smoothness and flatness, thereby reducing flow field disturbance. When the system is supplied with high-temperature ultrapure water at 80℃-85℃ to clean the inner wall of the pipe, the physical barrier layer 1 is heated. The large, regular outward expansion causes the outer edge of the arc-shaped guide channel 11 to adhere to and fit into the inner wall of the arc-shaped receiving channel 31, forming a "gear spline"-like structure to resist twisting and peeling during violent fluid pulsation. Simultaneously, this adherence effectively reduces contact thermal resistance, efficiently transferring the heat of the high-temperature ultrapure water to the outer buffer layer 4. During the high-temperature fluid flushing process, the stress generated by the fluid kinetic energy is spirally guided and dissipated along the continuous trajectory of the spiral groove 32 on the outer wall of the inner liner 3 and the spiral reinforcing ribs 42 sleeved on its exterior, preventing local collapse of the pipe wall. The outward radial expansion of the physical barrier layer 1 and the inner lining layer 3 strongly compresses the elastic sheet 43 located on the inner wall of the spiral reinforcing rib 42 and embedded inside the spiral groove 32. After being compressed, the elastic sheet 43 absorbs the thermal expansion volume transferred from the inner layer through its own elastic deformation compression, providing sufficient outward expansion capacity for the internal material of the pipe. Furthermore, as a shape memory metal sheet, the elastic sheet 43 undergoes phase change deformation under high-temperature heat transfer. This deformation process continuously changes the compressive force on the spiral groove 32, using minute deformation compression to increase the turbulence and disturbance effect of the internal high-temperature ultrapure water. This significantly improves the cleaning power for hard-to-reach areas. When the cleaning operation is completed and the water flow returns to normal temperature inside the pipe, the internal temperature of the pipe drops rapidly. The elastic sheet 43 of the shape memory metal material undergoes a martensitic phase transformation, instantly "unloading" the inward squeezing force and returning to its initial soft state. The dynamic effect of automatic pressure relief allows the inner PE material to naturally shrink back to its original position, which not only extends the overall fatigue life of the multi-layer PE nano-clean pipe, but also ensures that the pipe maintains its initial dimensional accuracy and extremely flat inner wall after frequent hot and cold cycles, effectively ensuring the normal operation of semiconductor processes.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multilayer PE nano-clean tube, comprising a physical barrier layer (1) and a high-density PE outer shell (2), characterized in that: It also includes an inner liner (3) and a buffer layer (4). The inner liner (3) is fitted outside the physical barrier layer (1), the buffer layer (4) is fitted outside the inner liner (3), and the high-density PE shell (2) is fitted outside the buffer layer (4). The inner wall of the physical barrier layer (1) is provided with a flow guide groove (11), and the inner wall of the inner liner (3) is provided with a receiving groove (31). When room temperature ultrapure water flows in the pipe, the physical barrier layer (1) is heated and expands into the flow guide groove (11). When the flow guide groove (11) expands, it expands into the receiving groove (31). When high temperature ultrapure water flows in the pipe, the flow guide groove (11) expands and fits the inner wall of the receiving groove (31). The receiving groove (31) transfers the heat of the high temperature ultrapure water to the buffer layer (4). The buffer layer (4) is heated and deforms and squeezes the outer wall of the receiving groove (31).

2. The multilayer PE nano-clean tube according to claim 1, characterized in that: The buffer layer (4) includes a sheath (41), a spiral reinforcing rib (42), and an elastic sheet (43). The buffer layer (4) is fitted outside the inner lining layer (3). The outer wall of the inner lining layer (3) is provided with a spiral groove (32). The spiral reinforcing rib (42) is fitted between the inner lining layer (3) and the buffer layer (4) and matches the spiral groove (32). The elastic sheet (43) is disposed on the inner wall of the spiral reinforcing rib (42) and located inside the spiral groove (32).

3. The multilayer PE nano-clean tube according to claim 2, characterized in that: The elastic sheet (43) is a memory metal sheet. Multiple elastic sheets (43) are arranged in a spiral direction along the spiral groove (32). The projection of each elastic sheet (43) along the radial direction of the physical barrier layer (1) is located within the projection of the corresponding receiving groove (31) along the radial direction of the physical barrier layer (1).

4. The multilayer PE nano-clean tube according to claim 1, characterized in that: Both the guide groove (11) and the receiving groove (31) are arc-shaped grooves. There are multiple guide grooves (11) and receiving grooves (31) arranged in a circular array. The projection of each guide groove (11) along the radial direction of the physical barrier layer (1) is located within the projection of the corresponding receiving groove (31) along the radial direction of the physical barrier layer (1).

5. A multilayer PE nano-clean tube according to claim 2, characterized in that: The phase change temperature of the elastic sheet (43) is the temperature conducted to the spiral groove (32) when high-temperature ultrapure water flows at 85°C.

6. The multilayer PE nano-clean tube according to claim 1, characterized in that: The depth of the receiving groove (31) is one-third to one-half of the opening width, and the opening width of the receiving groove (31) is greater than the opening width of the guide groove (11).

7. The multilayer PE nano-clean tube according to claim 2, characterized in that: The elastic sheet (43) is arc-shaped and its two ends are movably sleeved with the inner wall of the spiral reinforcing rib (42). The middle part of the elastic sheet (43) is in contact with the bottom of the spiral groove (32).

8. A method for preparing the multilayer PE nanotubes according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of physical barrier layer: The physical barrier layer (1) is extruded by an extrusion molding machine, and during the extrusion process, guide grooves (11) distributed in a circumferential array are formed on its inner wall by a die. S2. Preparation of inner liner: The inner liner (3) is extruded and coated on the outer wall surface of the physical barrier layer (1), and a receiving groove (31) corresponding to the radial projection of the guide groove (11) is formed on the inner wall of the inner liner (3) during extrusion, and a spiral groove (32) is simultaneously formed on the outer wall of the inner liner (3). S3. Assemble the buffer layer: The elastic sheet (43) which is a memory metal sheet is pre-installed on the inner wall of the spiral reinforcing rib (42) with its two ends movably sleeved; then, the spiral reinforcing rib (42) with the elastic sheet (43) is wound along the spiral direction and fitted into the spiral groove (32) of the inner liner (3), so that the middle part of the elastic sheet (43) contacts the bottom of the spiral groove (32), and then the outer sheath (41) is extruded. S4. Preparation of the outer shell: A high-density PE shell (2) is extruded and coated on the outside of the sheath (41) of the buffer layer (4), and then shaped after cooling and traction.

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