TPV (thermoplastic vulcanizate) pipeline forming process adopting silica gel composite core rod as lining

Abstract

The invention relates to the technical field of TPV pipeline forming, and provides a TPV pipeline forming process adopting a silica gel composite core rod as a lining, and the TPV pipeline forming process comprises the following steps: preparing a pipe blank of a TPV pipeline; a silica gel composite core rod serves as a lining to be arranged in the pipe blank in a penetrating mode, the silica gel composite core rod comprises an inner layer, a reinforcing wire layer and an outer layer, the inner layer and the outer layer are both silicone rubber layers, and reinforcing wires in the reinforcing wire layer are aramid fiber wires and / or polyester wires; putting the pipe blank into a mould; performing thermal forming; cooling is performed; and demolding to obtain the TPV pipeline. The TPV pipeline forming process disclosed by the invention has the following advantages: 1, the direct contact between the spring and the inner wall of the TPV pipe is avoided, and the leakage hidden danger caused by spring impressing is eliminated; the silica gel composite core rod is not prone to deformation, so that the service life of the silica gel composite core rod is prolonged, and the stability of the production takt is guaranteed; and thirdly, the quality risk that the inner hole of the TPV pipe fitting is blocked due to accidental breakage can be prevented.

Description

Technical Field

[0001] This invention relates to the field of TPV pipe forming technology, and more specifically, to a TPV pipe forming process using a silicone composite mandrel as an inner liner. Background Technology

[0002] In recent years, TPV piping has demonstrated advantages such as material recyclability and weight reduction while meeting automotive performance requirements. Therefore, TPV cooling water pipes have been increasingly developed and applied.

[0003] The TPV pipe forming process typically includes the following steps: preparing a TPV pipe blank; inserting an inner liner into the inside of the blank; placing the blank into a die; thermoforming; cooling; demolding to remove the die and inner liner to obtain the TPV pipe.

[0004] The applicant is the first company in China to develop TPV tubing as an alternative to traditional EPDM rubber tubing and use it in passenger vehicles. In the early stages of development, we experimented with using springs, EPDM mandrels, and pure silicone mandrels as inner liners for TPV tubing. When using spring liners, severe spring indentations appeared on the inner wall of the TPV tubing, leading to a risk of leakage. For example, prior art patent application CN202010804412.6 discloses a cooling pipe, a cooling tubing assembly, and a cooling pipe manufacturing method, using a spring liner for the cooling pipe; however, severe spring indentations appeared on the inner wall of the TPV tubing, resulting in a risk of leakage. Furthermore, when using EPDM mandrels and pure silicone mandrels as inner liners for TPV tubing, these mandrels were prone to deformation, had a short service life, affected production cycle time, or broke, posing a quality risk of product blockage.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to propose a TPV pipe molding process using a silicone composite mandrel as an inner liner, in order to solve the problems in the prior art where, when using a spring liner, there are severe spring imprints on the inner wall of the TPV pipe, leading to the risk of product leakage; and when using EPDM mandrels and pure silicone mandrels as inner liners for TPV pipe fittings, the EPDM mandrels and pure silicone mandrels are prone to deformation, have a short service life, affect production cycle, or break and pose a quality risk of product blockage.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A TPV pipe forming process using a silicone composite mandrel as an inner liner, the TPV pipe forming process comprising the following steps:

[0009] S1. Prepare the tube blank for TPV pipeline;

[0010] S2. A silicone composite mandrel is inserted as an inner liner inside the tube blank. The silicone composite mandrel includes an inner layer, a reinforcing wire layer and an outer layer from the inside to the outside. The inner layer and the outer layer are both silicone rubber layers, and the reinforcing wires in the reinforcing wire layer are aramid fiber wires and / or polyester wires.

[0011] S3. Place the tube blank into the fixture;

[0012] S4, thermoforming;

[0013] S5, Cooling;

[0014] S6. Demolding yields TPV pipes.

[0015] Furthermore, the reinforcing thread is an aramid fiber thread.

[0016] Furthermore, the aramid fiber yarn has a diameter of 1100d to 1700d, and the polyester yarn has a diameter of 1000d to 1500d.

[0017] Furthermore, the reinforcing thread is formed into a reinforcing thread layer through a braiding or knitting process.

[0018] Furthermore, when the diameter of the inner layer is φ14~φ19, the weight of the reinforcing line layer is 4.5~7.5g / 1000mm.

[0019] Furthermore, the hardness of the inner and outer layers is 70~90A.

[0020] Furthermore, in step S4, the thermoforming temperature is 150~160℃, and the thermoforming time is 20~30min.

[0021] Furthermore, in step S5, the cooling is divided into two steps. The temperature of the first step is 5~20℃ and the cooling time is 30~90s. The temperature of the second step is 5~15℃ and the cooling time is 3~5min.

[0022] Furthermore, in step S4, thermoforming is performed inside a tunnel furnace.

[0023] Furthermore, in step S1, a tube blank for the TPV pipeline is prepared using an extrusion process.

[0024] Compared with the prior art, the TPV pipeline molding process using a silicone composite mandrel as an inner liner described in this invention has the following beneficial effects:

[0025] 1) The TPV pipe forming process described in this invention uses a silicone composite mandrel as an inner liner. The silicone composite mandrel is inserted into the inside of the pipe blank as an inner liner of the TPV pipe, avoiding direct contact between the spring and the inner wall of the TPV pipe. This fundamentally eliminates the leakage risk caused by spring imprinting, greatly improves the sealing performance and reliability of the product, and ensures the safety of the product in use.

[0026] 2) The TPV pipe forming process described in this invention uses a silicone composite mandrel as an inner liner. Both the inner and outer layers are silicone rubber layers, which ensures good adhesion and sealing between the silicone composite mandrel and the inner wall of the TPV pipe. The reinforcing line layer can enhance the deformation resistance of the silicone composite mandrel. The silicone composite mandrel is not easily deformed, thereby extending its service life and ensuring the stability of the production cycle.

[0027] 3) The TPV pipeline molding process using a silicone composite mandrel as an inner liner described in this invention greatly enhances the fracture resistance of the silicone composite mandrel by the reinforcing line layer, effectively preventing accidental breakage. Even in the rare event of a breakage, the reinforcing line layer will hold the broken section, ensuring that the broken silicone composite mandrel can be pulled out of the TPV pipeline without being left inside. This completely avoids the quality risk of product pore blockage and improves the product's pass rate and quality stability. Attached Figure Description

[0028] Figure 1 This is one of the structural schematic diagrams of a silicone composite mandrel used as an inner liner in a TPV pipeline molding process according to an embodiment of the present invention;

[0029] Figure 2 This is the second schematic diagram of the structure of the silicone composite mandrel in the TPV pipeline molding process using a silicone composite mandrel as an inner liner, as described in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Silicone composite core rod; 11. Inner layer; 12. Reinforcing line layer; 13. Outer layer. Detailed Implementation

[0032] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0033] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Example 1

[0038] In existing technologies, when using spring liners, severe spring indentations appear on the inner wall of the TPV pipe, leading to a risk of leakage. When using EPDM mandrels or pure silicone mandrels as liners for TPV pipe fittings, these mandrels are prone to deformation, have short service life, affecting production cycle time, or may break, posing a quality risk of product blockage.

[0039] To address the aforementioned technical problems, the applicant proposes a TPV pipe forming process using a silicone composite mandrel as an inner liner. The TPV pipe forming process includes the following steps:

[0040] S1. Prepare a tube blank for a TPV pipeline, wherein the tube blank has a bending structure and a perforated structure is formed on the tube blank;

[0041] S2. Insert the silicone composite mandrel 1 as an inner lining inside the tube blank, such as... Figure 1 As shown, the silicone composite mandrel 1 includes an inner layer 11, a reinforcing wire layer 12, and an outer layer 13 from the inside out. The inner layer 11 and the outer layer 13 are both silicone rubber layers, and the reinforcing wires in the reinforcing wire layer 12 are aramid fiber wires and / or polyester wires.

[0042] S3. Place the tube blank into the fixture;

[0043] S4, thermoforming;

[0044] S5, Cooling;

[0045] S6. Demolding yields TPV pipes.

[0046] The TPV pipe forming process using a silicone composite mandrel as an inner liner described in this embodiment has the following advantages:

[0047] I. The TPV pipe molding process using a silicone composite mandrel as an inner liner described in this embodiment avoids direct contact between the spring and the inner wall of the TPV pipe, fundamentally eliminating the leakage risk caused by spring imprinting, greatly improving the sealing performance and reliability of the product, and ensuring the safety of product use.

[0048] II. The TPV pipe molding process described in this embodiment, which uses a silicone composite mandrel as an inner liner, features inner layer 11 and outer layer 13 both being silicone rubber layers. This ensures good adhesion and sealing between the silicone composite mandrel 1 and the inner wall of the TPV pipe. The reinforcing layer 12 significantly enhances the deformation resistance of the silicone composite mandrel 1. On one hand, this makes the silicone composite mandrel 1 less prone to deformation, maintaining shape stability. The silicone composite mandrel 1 can be reused multiple times, greatly extending its service life and ensuring stable production cycle. On the other hand, this provides a precise and stable inner cavity mold for the TPV pipe blank (especially complex blanks with bending and hole structures) during heating and softening, helping to maintain the dimensional accuracy of the TPV pipe and ensuring that the molded TPV pipe meets design requirements and satisfies the stringent dimensional standards for different application scenarios.

[0049] Third, the TPV pipeline molding process using a silicone composite mandrel as an inner liner described in this embodiment greatly enhances the fracture resistance of the silicone composite mandrel 1 and effectively prevents accidental breakage. Even if a breakage occurs with a very low probability, the fracture point will be held in place by the reinforcing layer, ensuring that the broken silicone composite mandrel 1 can be smoothly pulled out of the TPV pipeline as a whole or in sections, without being left inside the pipe. This completely avoids the quality risk of product pore blockage and improves the product's pass rate and quality stability.

[0050] Specifically, in step S4, the thermoforming temperature is 150~160℃ and the thermoforming time is 20~30min.

[0051] This design has the following key advantages:

[0052] 1. Optimize the crosslinking and melting balance of TPV materials: This temperature range precisely matches the dynamic vulcanization rubber phase melting temperature and plastic phase flow temperature of TPV materials. It can ensure that the material is fully softened, achieve good welding and shaping, while promoting the stable formation of the crosslinking network structure. It effectively avoids material degradation or performance decline caused by excessively high temperature, as well as insufficient plasticization or insufficient flow filling caused by excessively low temperature.

[0053] II. Ensuring the stability and service life of the silicone composite mandrel 1: The selected temperature is significantly lower than the critical temperature for conventional thermal aging or significant softening of silicone rubber materials, which can maximize the protection of the inner layer 11 and outer layer 13 of the silicone composite mandrel 1 to maintain elasticity and structural integrity in long-term thermal environments, preventing the silicone composite mandrel 1 from sticking, deforming, or being damaged due to overheating. Combined with the support of the reinforcing line layer 12, this thermoforming condition further extends the repeated service life of the silicone composite mandrel 1 and maintains its dimensional accuracy as an internal cavity mold.

[0054] Third, it can achieve efficient and uniform molding results: The 20-30 minute thermoforming time provides sufficient heat penetration and stress relaxation time for the tube blank (especially for parts with complex features such as bending and hole structure), ensuring that the TPV material can be uniformly and densely attached to the outer molding mold under the support of the mandrel, eliminating internal stress concentration, and making the final formed pipe dimension accurate, wall thickness uniform, structure stable, and hole structure edge clear and regular.

[0055] In this embodiment, the thermoforming temperature is 151°C and the thermoforming time is 30 minutes.

[0056] Preferably, in this embodiment, the reinforcing thread is an aramid fiber thread.

[0057] This configuration has the following significant advantages, which synergize with the overall technical solution of the present invention:

[0058] 1. Provides excellent dimensional stability and creep resistance, ensuring the molding precision of TPV pipelines: Aramid fibers possess extremely high tensile modulus and extremely low elongation, with very low thermal shrinkage. During thermoforming at 150~160℃, the reinforcing layer 12 composed of aramid fiber threads provides extremely rigid skeletal support for the silicone composite mandrel 1, effectively resisting any tensile, compressive, or bending deformation that may occur under heating and preform molding pressure. This ensures that the mandrel maintains high geometric and dimensional stability throughout the entire thermoforming cycle, thus providing an absolutely precise and non-deformable internal mold for complex TPV preforms with bending and hole structures. This directly guarantees the ultra-high precision and consistency of the final TPV pipeline product, especially the critical bending angles and hole dimensions, fully meeting the stringent tolerance requirements for fluid pipeline dimensions in the automotive, medical, and other fields.

[0059] 2. The silicone composite mandrel 1 possesses excellent fracture resistance and resistance to permanent deformation, significantly extending its service life and ensuring production safety: Aramid fibers have high strength and are lighter in weight; the reinforcing thread is made of aramid fiber, greatly improving the overall mechanical strength of the silicone composite mandrel 1, enabling it to withstand mechanical stresses such as tension and bending during repeated tube insertion and demolding processes, fundamentally eliminating the problems of easy deformation and breakage of traditional pure silicone or EPDM mandrels. Even if the outer layer 13 of the silicone composite mandrel 1 is damaged in extreme cases, the aramid fiber reinforcing layer 12 can firmly lock the broken part, preventing it from falling off or dispersing, ensuring that the silicone composite mandrel 1 can be safely and completely extracted as a whole. This eliminates the serious quality risk of pipeline blockage caused by silicone composite mandrel 1 material residue, while also increasing the number of times the silicone composite mandrel 1 can be reused by orders of magnitude, significantly reducing consumable costs and stabilizing production cycle time.

[0060] 3. Aramid fibers possess excellent high-temperature resistance and thermal stability, perfectly matching the thermoforming temperature range of 150~160℃: Aramid fibers have a wide long-term service temperature range, exhibiting extremely high performance retention at thermoforming temperatures of 160℃ and below, without melting, softening, or significant thermal aging, ensuring the structural stability and performance non-degradation of the silicone composite mandrel 1 during the thermoforming process. This characteristic makes it fully adaptable to thermoforming temperatures of 150~160℃ and thermoforming times of 20~30 minutes.

[0061] 4. Achieves lightweight and ease of operation: Although aramid fibers have extremely high strength, they also have low density. This means that the reinforced silicone composite mandrel 1 achieves exceptional strength while maintaining very limited weight gain. This significantly reduces the labor intensity of operators, facilitates the insertion and extraction of the silicone composite mandrel 1 within long tube blanks, and improves the operability and production efficiency of the process. It is especially beneficial for the large-scale continuous production of complex pipelines.

[0062] Specifically, in step S5, cooling is divided into two steps.

[0063] Specifically, in step S5, the temperature of the first cooling step is 18°C ​​and the cooling time is 60 seconds; the temperature of the second cooling step is 8°C and the cooling time is 4 minutes.

[0064] This setup helps the TPV material crystallize and stabilize, releases internal stress, and achieves better final product performance, giving the silicone composite mandrel 1 good thermal stability and strength.

[0065] Specifically, in step S4, thermoforming is performed inside a tunnel furnace.

[0066] This setup not only enables continuous, stable, and uniform heat treatment, ensuring process consistency and product uniformity, but also provides precise temperature control and zoned regulation capabilities, optimizing the crosslinking and molding process of TPV materials. Furthermore, it significantly improves production efficiency and cycle time stability.

[0067] Specifically, in step S1, a tube blank for the TPV pipeline is prepared using an extrusion process.

[0068] This setting can further improve production efficiency.

[0069] Since the specific steps for preparing TPV pipe blanks using the extrusion process are existing technologies, they will not be described in detail here.

[0070] Since the specific structure of the fixture is existing technology, it will not be described in detail here.

[0071] Specifically, in step S6, the mold and liner are removed to obtain the TPV pipeline.

[0072] The preparation of the silicone composite mandrel 1 includes: extruding an inner silicone rubber layer 11; forming a reinforcing thread layer 12 by braiding or knitting reinforcing threads; and extruding an outer silicone rubber layer 13.

[0073] Since the extruded silicone rubber inner layer 11 and the extruded silicone rubber outer layer 13 are existing technologies, they will not be described in detail here.

[0074] In this embodiment, the inner layer 11 has a diameter of φ14.3, and the reinforcing line layer 12 weighs 6.5g / 1000mm.

[0075] This greatly reduces the labor intensity of operators, facilitates the insertion and extraction of silicone composite mandrel 1 in long tube blanks, improves the operability and production efficiency of the process, and is especially beneficial for the large-scale continuous production of complex pipelines.

[0076] Specifically, in this embodiment, such as Figure 2As shown, the reinforcing thread is formed into a reinforcing layer 12 by a knitting process.

[0077] Specifically, the reinforcing thread is formed into a reinforcing thread layer 12 using a 12-needle knitting machine through a knitting process.

[0078] Since knitting technology is an existing technology, it will not be elaborated here.

[0079] Furthermore, the aramid fiber yarn has a diameter of 1100d to 1700d.

[0080] Specifically, in this embodiment, the aramid fiber thread has a diameter of 1100d.

[0081] The hardness of the inner layer 11 and the outer layer 13 is 70~90A.

[0082] This design has the following advantages:

[0083] 1. A hardness range of 70~90A gives the silicone layer both the necessary flexibility and sufficient rigid support. For the inner layer 11, this hardness allows it to pass through the tube blank well and conform to the bending structure without getting stuck. For the outer layer 13, this hardness allows it to form a tight and uniform contact and support with the inner wall of the TPV tube blank during thermoforming. It is neither too soft (<70A) which would result in insufficient support and easy deformation due to compression, affecting the accuracy of the inner diameter of the tube, nor too hard (>90A) which would result in poor adhesion to complex tube walls or introduce additional internal stress into the TPV material.

[0084] Second, the moderate hardness allows the inner layer 11 and outer layer 13 to work synergistically with the reinforcing layer 12 to construct a stable and durable composite structure. The inner layer 11 and outer layer 13, as the matrix, provide elasticity, sealing, and an adhesive interface with the reinforcing lines; the reinforcing layer 12 provides a tensile and creep-resistant framework. A hardness of 70~90A ensures that the inner layer 11 and outer layer 13 of the silicone matrix have sufficient strength and modulus to effectively transfer stress to the reinforcing layer 12 and resist permanent compression deformation during repeated use. Together, they make the silicone composite mandrel 1 less prone to deformation, reusable, and with a long service life.

[0085] Furthermore, the hardness of the inner layer 11 and the outer layer 13 is 80A.

[0086] Example 2

[0087] In this embodiment, unlike in embodiment 1, as follows: Figure 1 As shown, the reinforcing wire is formed into a reinforcing wire layer 12 through a braiding process.

[0088] Specifically, the reinforcing thread is formed into a reinforcing thread layer 12 using a 24-spindle braiding machine through a braiding process.

[0089] Since the weaving technique is existing technology, it will not be described in detail here.

[0090] Specifically, in this embodiment, the aramid fiber thread has a diameter of 1700d.

[0091] In this embodiment, the thermoforming temperature is 153°C and the thermoforming time is 25 minutes.

[0092] Specifically, in step S5, the temperature of the first cooling step is 20°C and the cooling time is 90 seconds; the temperature of the second cooling step is 5°C and the cooling time is 5 minutes.

[0093] Specifically, the weight of the reinforcing line layer 12 is 5.1g / 1000mm.

[0094] This greatly reduces the labor intensity of operators, facilitates the insertion and extraction of silicone composite mandrel 1 in long tube blanks, improves the operability and production efficiency of the process, and is especially beneficial for the large-scale continuous production of complex pipelines.

[0095] Furthermore, after extruding the silicone rubber inner layer 11, it needs to be left to stand for 3-5 hours before using reinforcing wires to form the reinforcing wire layer 12 through a braiding process.

[0096] This design has the following advantages:

[0097] I. Ensuring the dimensional accuracy and initial shape stability of the inner layer 11 to provide an ideal substrate for core manufacturing processes: This is because the silicone rubber inner layer 11 is in a thermoplastic state when it is first extruded, with a relatively soft texture and incomplete release of internal stress. If it is woven immediately at this time, the pulling force of the weaving will cause the inner layer 11 to deform. Therefore, it is left to stand for 3-5 hours to allow it to cool fully and complete the stress relaxation process, thereby obtaining a dimensionally stable and mechanically uniform cured inner layer 11. This provides an ideal substrate with a regular shape, moderate hardness, and resistance to deformation for subsequent weaving / knitting processes. It fundamentally avoids problems such as uneven overall dimensions and irregular wall thickness of the silicone composite mandrel 1 caused by excessive deformation of the inner layer 11 during the reinforcement line laying process, ensuring that the reinforcement line layer 12 can be accurately and uniformly attached to the surface of the inner layer 11, laying the foundation for the dimensional accuracy and structural consistency of the final silicone composite mandrel 1.

[0098] 2. Protect the integrity of the inner layer 11 material and avoid mechanical damage and performance degradation: The cooling process allows the inner layer 11 to reach sufficient strength and elastic modulus, which can effectively resist mechanical stress during the weaving process and prevent physical damage to the inner layer 11, thereby maintaining the overall reliability, durability and service life of the silicone composite mandrel 1.

[0099] III. Optimize and enhance the adhesion and structural uniformity of the enhanced line layer 12 to improve the overall performance of the silicone composite mandrel 1.

[0100] IV. Improve process controllability and production stability to ensure product consistency and yield.

[0101] In this embodiment, after the inner silicone rubber layer 11 is extruded, it needs to be left to stand for 4 hours before the reinforcing thread layer 12 is formed by braiding the reinforcing thread.

[0102] Furthermore, the hardness of the inner layer 11 and the outer layer 13 is 70A.

[0103] Example 3

[0104] In this embodiment, unlike in Embodiment 1, the reinforcing lines in the reinforcing line layer 12 are polyester lines.

[0105] This design has the following advantages:

[0106] I. Achieving excellent comprehensive mechanical balance and fatigue resistance, ensuring the shape stability of the mandrel during long-term use. Polyester yarn possesses high strength, high modulus, and excellent creep and fatigue resistance. Using it as the reinforcing layer 12 effectively endows the silicone composite mandrel 1 with excellent tensile and bending resistance, enabling it to resist plastic deformation and maintain its initial shape and dimensional accuracy over a long period during repeated tube threading, demolding, and thermoforming cycles. This directly guarantees the accuracy and stability of the inner cavity mold during the heating and softening of TPV tube blanks (especially complex blanks with bending and hole structures), which is crucial for maintaining the dimensional accuracy of the formed TPV pipeline and meets the standard requirements of stringent application scenarios.

[0107] II. Providing excellent flexibility and bending compliance, particularly suitable for complex pipe structures. Compared with high-performance fibers such as aramid, polyester yarns typically exhibit better flexibility and flexural fatigue performance while possessing sufficient strength. This allows the silicone composite mandrel 1 reinforced with polyester yarns to pass through bends more smoothly when threading TPV tube blanks with complex, multi-angle bending structures, reducing frictional resistance with the inner wall of the tube blank, lowering the difficulty of threading, and reducing the risk of damage to the mandrel itself. Simultaneously, during thermoforming, its flexibility helps the mandrel better conform to the inner wall shape at the bend of the tube blank, providing more uniform support pressure, thus contributing to the formation of a smooth inner wall and uniformly transitioned bent pipe structure.

[0108] Third, it possesses good cost-effectiveness and processability, facilitating industrial production and promotion: Polyester yarn is a mature industrial fiber, with significantly lower costs than specialty fibers such as aramid, and a stable supply. Polyester yarn is easy to weave, knit, and process, and the technology is mature.

[0109] IV. The polyester thread exhibits excellent adhesion and heat resistance to the silicone rubber layers of the inner layer 11 and outer layer 13. The surface of the polyester thread is typically easy to treat to achieve good adhesion to the rubber material. Through appropriate adhesive systems or surface treatments, a strong interfacial bond can be ensured between the polyester reinforcing thread layer 12 and the inner layer 11 and outer layer 13, preventing interlayer delamination during repeated use. Furthermore, the upper limit of the long-term service temperature of the polyester thread is essentially matched with the thermoforming temperature of this design (150~160℃). Within this temperature range, its performance remains stable for short periods, enabling it to work in conjunction with the silicone layer to withstand the thermal stress of the thermoforming process, ensuring the structural integrity and service life of the silicone composite mandrel 1 under thermal conditions.

[0110] In this embodiment, the thermoforming temperature is 150°C and the thermoforming time is 20 minutes.

[0111] Specifically, in step S5, the temperature of the first cooling step is 6°C and the cooling time is 30 seconds; the temperature of the second cooling step is 5°C and the cooling time is 3 minutes.

[0112] Furthermore, the hardness of the inner layer 11 and the outer layer 13 is 90A.

[0113] In this embodiment, the polyester yarn has a thickness of 1000D.

[0114] Example 4

[0115] In this embodiment, unlike in Embodiment 1, the reinforcing threads in the reinforcing thread layer 12 are aramid fiber threads and polyester threads.

[0116] In this embodiment, the polyester yarn has a thickness of 1500D.

[0117] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A TPV pipe forming process using a silicone composite mandrel as an inner liner, characterized in that, The TPV pipeline forming process includes the following steps: S1. Prepare the tube blank for TPV pipeline; S2. A silicone composite mandrel (1) is inserted into the interior of the tube blank as an inner liner. The silicone composite mandrel (1) includes an inner layer (11), a reinforcing wire layer (12), and an outer layer (13) from the inside to the outside. The inner layer (11) and the outer layer (13) are both silicone rubber layers, and the reinforcing wires in the reinforcing wire layer (12) are aramid fiber wires and / or polyester wires. S3. Place the tube blank into the fixture; S4, thermoforming; S5, Cooling; S6. Demolding yields TPV pipes.

2. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, The reinforcing thread is an aramid fiber thread.

3. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, The aramid fiber yarn has a thickness of 1100d~1700d, and the polyester yarn has a thickness of 1000~1500D.

4. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, The reinforcing thread is formed into a reinforcing thread layer (12) by a braiding or knitting process.

5. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, When the diameter of the inner layer (11) is φ14~φ19, the weight of the reinforcing line layer (12) is 4.5~7.5g / 1000mm.

6. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, The hardness of the inner layer (11) and the outer layer (13) is 70~90A.

7. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, In step S4, the thermoforming temperature is 150~160℃ and the thermoforming time is 20~30min.

8. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, In step S5, the cooling is divided into two steps. The temperature of the first step is 5~20℃ and the cooling time is 30~90s. The temperature of the second step is 5~15℃ and the cooling time is 3~5min.

9. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, In step S4, thermoforming is performed inside a tunnel furnace.

10. The TPV pipeline molding process using a silicone composite mandrel as an inner liner according to claim 1, characterized in that, In step S1, a tube blank for the TPV pipeline is prepared using an extrusion process.

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