High-strength polyurethane winding pultrusion pipe for railway cable crossing and its preparation method

Abstract

The application discloses a high-strength polyurethane winding pultrusion pipe for railway cable and a preparation method thereof. The pipe is a polyurethane winding pultrusion pipe, and the content of the reinforcing fiber in the pipe is 75-82% of the total weight of the pipe. The pipe is prepared by using a cushion block to assist a core rod and a mold to form the pipe, and a yarn cloth felt link is arranged. The distribution and arrangement of the reinforcing fiber are performed according to the cross-sectional view of the pipe, the amount of the axial reinforcing fiber is increased, and the lateral compressive force is improved. A guide support is arranged in the glue injection box to ensure the glue injection and immersion space, and glue is injected in multiple directions to avoid the reaction of the glue before solidification, so that the pipe reaches the strength requirement in design. Through professional test, the maximum stress of the pipe can reach more than 505Mpa, which fully meets the design requirements of the strength and long service life of the pipe, and the pipe has good practical value and application prospect.

Description

Technical Field

[0001] This invention relates to a duct for railway cables crossing rails, and more particularly to a high-strength polyurethane spiral pultruded duct for railway cables crossing rails and its preparation method. Background Technology

[0002] When laying railway tracks, cables need to be encased in conduits and pre-embedded within the tracks to protect them and extend their lifespan. Because these conduits are used for railway track laying, they require a certain level of strength, especially those used for crossing rails, which must meet the requirements for cable passage.

[0003] Currently, there are two solutions for cable crossing above rails. One is to install cable trays that pass over the rails, avoiding cable compression. However, this method has many limitations, such as high cost, space requirements, and unsuitability for cable tray installation in some environments. The other, and more commonly used, solution is to pre-embed conduits under the rails. Traditionally, metal steel pipes are used for cable crossing to protect the cables. However, due to their inconvenient installation, difficulty in rust and corrosion prevention, and the risk of uneven welding damaging the cables, non-metallic conduits have been increasingly used in recent years. Commonly used non-metallic pipes include PE pipes, PVC pipes, and fiberglass pipes. However, PE and PVC pipes are not strong enough, and during installation, deformation or cracking due to rebar binding or concrete pouring can prevent cables from passing through, or collapse during later use can damage the internal cables. While fiberglass (SMC) pipes are lightweight, strong, stable, and corrosion-resistant, their low modulus of elasticity makes them prone to deformation, poor temperature resistance, and aging, and their low shear strength still leads to deformation and cracking issues when used for cable crossing.

[0004] Polyurethane, short for polyurethane, is a thermoplastic polymer compound. It offers better stability, chemical resistance, resilience, and mechanical properties than PE and PVC pipes, and is used in construction, automotive, aerospace, and thermal insulation industries. Fiber materials are structured materials formed from fibrous substances through textile processing. They possess high strength properties, and combining them with thermoplastic materials can enhance overall strength. One existing method for combining fiber materials with polyurethane is the filament pultrusion process. This involves winding the fiber material around an inner liner or liner layer, placing it in a sealed injection box, and then injecting two-component polyurethane into the box under pressure. After high-temperature curing, a polyurethane filament pultruded pipe is formed. For example, Chinese patent document CN114228198A discloses a processing method for high-pressure resistant polyurethane spiral pultruded pipe. The method involves wrapping the pipe lining material onto a mandrel to form a tubular lining layer, then using fibers to form a circumferential fiber winding layer on the surface of the lining layer; and then using fibers to form a cross-fiber winding layer on the surface of the circumferential fiber winding layer. The method then proceeds to the impregnation process, where a two-component polyurethane material is injected under high pressure into the pressurized impregnation process for penetration impregnation treatment. After impregnation, the method proceeds to the curing process for polyurethane curing at high temperature to obtain the corresponding cured high-pressure resistant polyurethane spiral pultruded pipe.

[0005] However, the current filament winding pultrusion process has at least the following drawbacks: 1) Insufficient fiber content and inadequate axial support, failing to meet rail crossing requirements. Existing polyurethane filament pultruded pipes use a limited fiber winding method, winding the fiber around the central axis of the pipe. This results in insufficient axial support, leading to bending and deformation during rail crossing, making it difficult for cables to pass or causing damage, thus failing to meet the requirements for rail-crossing pipes. 2) The pipe body exhibits delamination or micro-cracks, making it prone to cracking and leakage during use. Directly winding fiber material onto the inner lining tube or inner lining layer and then injecting adhesive for curing, or using multi-layer winding to increase fiber content, creates gaps between the fiber material and the inner lining tube layer, or between the layers of multi-layered fiber material. This results in insufficient contact with the polyurethane, hindering impregnation and easily leading to incomplete impregnation, delamination, or micro-cracks. Over long-term use, this can cause cracking and leakage. Furthermore, water accumulation can occur in both railway and other operating environments. Once water enters the track pipe, it not only corrodes the cable but also affects cable signal transmission, increases maintenance costs, and hinders drainage and repair. 3) Using multiple injection boxes for adhesive injection can cause resin reaction before curing, leading to mold blockage. Existing polyurethane wound pultruded pipes use multiple injection boxes during adhesive injection, which can easily cause the two-component polyurethane to react before curing, resulting in mold blockage. This hinders smooth production and affects product quality.

[0006] Furthermore, in actual production, the reactivity of each component of polyurethane, the injection ratio between components, and the injection pressure all affect the performance of the pipe. Therefore, how to produce polyurethane pipes suitable for railway cable crossings remains an urgent problem to be solved. Summary of the Invention

[0007] To address the aforementioned problems and achieve the above objectives, this invention provides a high-strength polyurethane spiral pultruded pipe for railway cable crossings and its preparation method. The reinforcing fiber content accounts for 75-82% of the total pipe weight, effectively increasing the pipe's strength. Furthermore, it employs padding blocks to assist the mandrel and mold forming, increasing the amount of axial reinforcing fiber. By setting guide supports inside the injection box, it ensures sufficient impregnation space, and by using multi-directional injection, it avoids pre-curing reactions, ensuring the pipe meets the designed strength requirements. The specific technical solution is as follows:

[0008] First, the present invention provides a railway cable crossing pipe, which is a polyurethane spiral pultruded pipe. Its structure includes a main body made of thermosetting polyurethane injection molding, spiral reinforcing fibers, longitudinal reinforcing fibers and mesh reinforcing partitions distributed in the main body; and the content of spiral reinforcing fibers, longitudinal reinforcing fibers and mesh reinforcing partitions accounts for 75 to 82% of the total weight of the crossing pipe.

[0009] Preferably, the wound reinforcing fiber body is formed by multiple layers of bidirectional winding of reinforcing fiber bundles around the axial direction of the rail-passing pipe; the mesh reinforcing partition is distributed at equal intervals along the axial direction of the rail-passing pipe in the pipe wall; the longitudinal reinforcing fiber body is formed by reinforcing fiber bundles being longitudinally distributed around the axial direction of the rail-passing pipe in the pipe wall.

[0010] More preferably, the reinforcing fiber bundles of the wound reinforcing fiber body and the reinforcing fiber bundles of the longitudinal reinforcing fiber body are both made of basalt fiber, and the mesh reinforcing interlayer is made of polyester felt, the shape of which is consistent with the cross-section of the rail passage pipe, and the area is smaller than the cross-sectional area of ​​the rail passage pipe.

[0011] The aforementioned railway cable crossing pipe has a polygonal outer wall and a water guide groove that is recessed into its inner wall.

[0012] Secondly, the present invention provides a forming mold for the aforementioned railway cable rail-passing pipe, including a mandrel, a forming mold shell, and a pad; the outer dimensions of the mandrel are the inner hole shape and size of the rail-passing pipe, it penetrates the forming mold shell, and is positioned at the central axis position of the forming mold shell cavity by the pad; the inner cavity cross section of the forming mold shell is polygonal, and its cavity wall is provided with raised water groove forming strips.

[0013] Preferably, both the mandrel and the molding shell are made of Cr. 12Made of chrome-plated material after MoV heat treatment, the mandrel is positioned on the central axis of the forming mold cavity; the pad is made of No. 45 steel and is distributed on the upper and lower sides of the two traction clamps at both ends of the forming mold, and its thickness is consistent with the wall thickness of the railway cable rail passage pipe.

[0014] Furthermore, the present invention provides a glue injection box for injection molding of the aforementioned railway cable rail passage pipe, comprising a glue injection box body, wherein the glue injection box body is provided with a glue injection cavity communicating with the molding mold cavity, wherein a plurality of guide supports are provided in the glue injection cavity to separate the reinforcing fiber bundles to form an impregnation space, and the supports are provided with a plurality of impregnation holes.

[0015] Preferably, the glue injection box body is provided with a plurality of glue injection holes; the glue injection holes are distributed on the side wall of the glue injection box body and are located between the two guide brackets or between the guide brackets and the side wall of the glue injection box body.

[0016] In addition, the present invention also provides a method for preparing the aforementioned railway cable track-crossing duct, which is prepared using the aforementioned molding mold and injection box, and specifically includes the following steps:

[0017] 1) Mold assembly: Pass the mandrel through the guide pipe to form the cavity of the mold shell, and adjust the position of the mandrel to the center of the mold shell cavity using shims;

[0018] 2) Preparation of adhesive solution: Prepare a two-component thermosetting polyurethane resin, including resin A and resin B; the components of resin A include urethane, ether, ester, urethane and internal release agent; resin B contains isocyanate; and the mass ratio of resin A to resin B is 105 to 108:100.

[0019] 3) Adjusting the mandrel: Adjust the fixed end of the mandrel to fix its relative position with the pipe forming mold shell;

[0020] 4) Arrange the yarn felt: Cut the polyester felt to the appropriate size according to the cross-sectional diagram of the rail pipe, and position it at the predetermined position using a felt guide; then distribute and arrange the reinforcing fiber bundles according to the cross-sectional diagram of the rail pipe.

[0021] 5) Fiber threading: Mark several areas on the threading plate according to the design, thread the basalt fibers into the holes of the corresponding yarn collecting plate according to the designed quantity, and then guide them out through the guide bracket in the glue injection box.

[0022] 6) Pultrusion and winding: The molding die is heated, and the temperature of its inlet, middle and outlet is controlled. At the same time, the prepared resin A and resin B are injected into the corresponding glue buckets. After the temperature of the molding die stabilizes, the pultrusion equipment, winding equipment and glue injection machine are turned on at the same time. The glue is injected and impregnated according to the set injection pressure and ratio. Pultrusion is carried out according to the set traction speed. The number of reinforcing fiber layers is adjusted according to the traction speed. After the glue injection and impregnation are cured, a high-strength railway cable rail passage pipe is obtained.

[0023] As a preferred technical solution, in step 2), the mass ratio of urethane, ether, ester, urea, urethane, and internal release agent in resin A is 50:35:8:5:3; the isocyanate contained in resin B is diphenylmethane diisocyanate; in step 6), the molding die is heated, and the temperatures of its inlet, middle, and outlet are controlled at 100-120°C, 130-150°C, and 150-170°C, respectively; the injection temperature is 20-25°C, and the pressure is 1.5-2.5 MPa; the traction speed is 0.35-0.5 m / min; and the number of layers of the winding reinforcing fiber is one layer in each direction.

[0024] The beneficial effects of this invention are:

[0025] 1) This invention is the first to use polyurethane spiral pultruded pipe as a railway cable crossing pipe. Its reinforcing fiber content accounts for 75-82% of the total weight of the pipe, which effectively ensures the strength requirements of polyurethane pipe as a railway cable crossing pipe. Furthermore, through process improvement, its axial fiber support is increased and the polyurethane component impregnation is improved to ensure the stress resistance of the pipe body and ensure its adaptability to the underground crossing environment and service life.

[0026] 2) This invention uses pad blocks to assist the core rod and mold to form the pipe. The core rod is inserted into the mold cavity, and the pad blocks are placed between the core rod and the mold to form a pipe wall space. Reinforcing fibers are arranged by polyester felt, which avoids the use of inner lining tubes or inner lining layers, making the pipe body more integral, solving the problem of delamination cracks, and enhancing the strength and performance of the pipe body.

[0027] 3) By setting up polyester felt, the present invention enables the reinforcement fibers to be arranged arbitrarily according to the designed strength and position, increases the amount of axial fiber arrangement in the tube, increases the transverse strength of the tube, improves its ability to resist pressure, and ensures the safety of the cable in the rail pipe.

[0028] 4) The injection box of this invention is equipped with a guide bracket inside, which allows the reinforcing fibers to form space, facilitating rapid impregnation of polyurethane; and the injection is carried out in multiple directions, avoiding the phenomenon of resin reaction and mold blockage before curing when using multiple injection boxes, thereby improving production efficiency and ensuring product quality.

[0029] 5) The rail-crossing pipe of this invention has a low specific gravity, making it convenient for transportation and installation; it is also impact-resistant and corrosion-resistant, able to withstand some collisions and frictions that are unavoidable during the production process, and can be used in some special environments such as acid and alkali environments and coastal environments; in addition, it has good insulation properties, and as a rail-crossing pipe for railway cables, it can avoid the harm caused by conductivity.

[0030] 6) Professional testing has shown that the maximum stress on the pipeline can reach over 505 MPa, and its pressure resistance is twice that of cast iron and 6 to 8 times that of ordinary SMC material, meeting the long-life design requirements for rail-crossing pipes. Furthermore, the rail-crossing pipe of this invention can be segmented by designing water guide channels and connecting elbows. After connecting with 45-degree elbows, it leads out to the ground, replacing manholes. This facilitates branch cable transfer and installation, as well as drainage, demonstrating good practical value and application prospects. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the high-strength polyurethane wound pultruded pipe structure for railway cable crossing according to the present invention;

[0032] Figure 2 This is a schematic diagram of the internal structure of the rail-crossing pipe of the present invention;

[0033] Figure 3 This is a schematic diagram of the assembly of the guide pipe core, pad block, and molding shell of the present invention;

[0034] Figure 4 This is a schematic diagram of the glue injection box structure of the present invention;

[0035] Figure 5 This is a stress cloud diagram of the cross-section of the pipeline passing through the rails according to the present invention;

[0036] Figure 6 This is a cloud diagram showing the minimum stress on the cross-section of the pipeline of the present invention.

[0037] Figure 7 This is a cloud diagram showing the maximum stress in the cross-section of the pipeline passing through the rails according to the present invention.

[0038] Figure 8 This is a strain contour plot of the cross-section of the pipeline of the present invention.

[0039] Figure 9 This is a cloud diagram showing the cross-sectional deformation of the pipeline of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments and accompanying drawings.

[0041] Example 1

[0042] This embodiment describes the fabrication of a high-strength polyurethane wound pultruded pipe for railway cable crossing, the structure of which is as follows: Figure 1 and Figure 2 As shown, its structure includes a main body injection molded from thermosetting polyurethane, and a spirally wound reinforcing fiber body, a longitudinally reinforcing fiber body, and a mesh-like reinforcing partition layer distributed within the main body; furthermore, the content of the spirally wound reinforcing fiber body, the longitudinally reinforcing fiber body, and the mesh-like reinforcing partition layer accounts for 75-82% of the total weight of the rail-crossing pipe. The spirally wound reinforcing fiber body is formed by multiple layers of reinforcing fiber bundles wound bidirectionally around the axial direction of the rail-crossing pipe; the mesh-like reinforcing partition layer is distributed at equal intervals along the axial direction of the rail-crossing pipe in the pipe wall; the longitudinally reinforcing fiber body is formed by reinforcing fiber bundles longitudinally distributed around the axial direction of the rail-crossing pipe in the pipe wall. The reinforcing fiber bundles of the spirally wound reinforcing fiber body and the reinforcing fiber bundles of the longitudinally reinforcing fiber body are both made of basalt fiber, and the mesh-like reinforcing partition layer is made of polyester felt, the shape of which is consistent with the cross-section of the rail-crossing pipe, but the area is smaller than the cross-sectional area of ​​the rail-crossing pipe. The outer wall of the rail-crossing pipe is polygonal, and a water-guiding groove recessed into its inner wall is provided on the outer wall. The specific preparation method is as follows:

[0043] 1) Preparation of forming mold: A mandrel is designed and prepared according to the bore shape and size requirements of the through-track pipe; a forming mold is designed and prepared according to the outer wall shape and size of the through-track pipe; and a pad is designed and prepared for later use. The mandrel and the forming mold for the through-track pipe are both made of Cr. 12 Made of chrome-plated material after MoV heat treatment, the mandrel is positioned on the central axis of the forming mold cavity; the pads are made of 45# steel and are distributed on the upper and lower sides of the two traction clamps at both ends of the forming mold, with their cross-sectional thickness consistent with the shape and wall thickness of the pipeline to ensure that the pipeline is not crushed. Figure 3 As shown. Its injection-molded injection box includes an injection box body, within which an injection cavity communicating with the molding mold cavity is provided. Multiple guide supports are arranged within the injection cavity to separate the reinforcing fiber bundles, forming an impregnation space. The supports have multiple impregnation holes, and the injection box body has multiple injection holes. The injection holes are distributed on the sidewalls of the injection box body, and are located between two guide supports or between the guide supports and the sidewalls of the injection box body, such as... Figure 4 As shown.

[0044] 2) Preparation of adhesive solution: Prepare resin A adhesive solution by mixing urethane, ether, ester, urea, urethane and internal release agent in a mass ratio of 50:35:8:5:3. At the same time, prepare resin B adhesive solution with diphenylmethane diisocyanate as the main component for later use.

[0045] 3) Adjusting the mandrel: Insert the prepared mandrel into the mold cavity, and use the spacers to adjust and position the mandrel at the center of the mold cavity. Fix the mandrel's position relative to the pipe forming mold using its fixed end. Figure 2 As shown;

[0046] 4) Fabric Felt Arrangement: Cut the polyester felt to the appropriate size according to the cross-sectional diagram of the duct, and position it in the appropriate location using a felt guide; then distribute and arrange the reinforcing fibers according to the cross-sectional diagram of the duct. The principle is to evenly distribute the reinforcing fibers according to the cross-sectional area of ​​each part of the duct, and to reasonably arrange the reinforcing fibers axially to enhance the compressive strength of the pipe body.

[0047] 5) Fiber threading: Mark several areas on the threading plate according to the design, and thread the basalt fibers into the holes of the corresponding yarn collecting plate according to the designed quantity, and set them aside.

[0048] 6) Pultrusion and winding: Heat the molding die, controlling the inlet temperature to 130℃, the intermediate temperature to 140℃, and the outlet temperature to 160℃. Simultaneously, inject the prepared resin A and resin B solutions into the corresponding glue tanks. After the molding die temperature stabilizes, simultaneously turn on the pultrusion equipment, winding equipment, and glue injection machine. Inject and impregnate the resin according to the set injection pressure and ratio, and perform pultrusion according to the set traction speed. Adjust the number of basalt fiber layers wound according to the traction speed. Specific operation is as follows:

[0049] a. Open the winding machine panel, set the winding speed, and weave the fiberglass to be wound onto the longitudinal fiberglass.

[0050] b. Turn on the traction equipment and start the hydraulic cylinder;

[0051] c. Connect the winding encoder to the front fiberglass and start the automatic winding function;

[0052] d. Connect the injection tube to the injection port of the mold and start the automatic injection function;

[0053] e. Start the traction machine to begin traction of the profile. At this time, the encoder of the winding machine and the probe of the glue injection machine receive the operation command and begin automatic winding and glue injection.

[0054] In this embodiment, the content of basalt fiber reinforcing fiber is controlled to account for 75% to 82% of the total weight of the pipe, preferably 80% to 82%, and most preferably 82%; the polyurethane spiral pultruded pipe obtained after injection impregnation and curing is the high-strength railway cable rail-crossing pipe.

[0055] Example 2: The reinforcing fiber content accounts for 73% of the total pipe weight.

[0056] This embodiment also describes the preparation of a high-strength polyurethane-wound pultruded pipe for railway cable crossing. The external shape and inner diameter of this pipe are the same as in Example 1, and the reinforcing fiber content accounts for 73% of the total weight of the pipe. Other operations are the same as in Example 1 to obtain a polyurethane-wound pultruded pipe, which serves as comparative product 1.

[0057] Example 3: The reinforcing fiber content accounts for 85% of the total pipe weight.

[0058] This embodiment also describes the preparation of a high-strength polyurethane-wound pultruded pipe for railway cable crossing. The external shape and inner diameter of this pipe are the same as in Example 1, and the reinforcing fiber content accounts for 85% of the total weight of the pipe. Other operations are the same as in Example 1 to obtain a polyurethane-wound pultruded pipe, which serves as comparative product 2.

[0059] Example 4 does not use pads

[0060] This embodiment also describes the preparation of a high-strength polyurethane-wound pultruded pipe for railway cable crossings. The external shape and inner diameter of this pipe are identical to those in Example 1, and the reinforcing fiber content accounts for 82% of the total pipe weight. However, the preparation method differs in that the mandrel adjustment step does not use a pad; instead, basalt fiber reinforcing fibers are directly wrapped around the mandrel to form an inner lining layer, followed by impregnation. Other operations are the same as in Example 1, resulting in a polyurethane-wound pultruded pipe, which serves as comparative product 3.

[0061] Example 5: No axial reinforcing fibers provided

[0062] This embodiment also prepares a high-strength polyurethane wound pultruded pipe for railway cable crossing. The external shape and inner diameter of the pipe structure are the same as those in Embodiment 1. The reinforcing fiber content also accounts for 82% of the total weight of the pipe. However, it does not perform the yarn and felt laying step, does not use polyester felt, and does not set axial reinforcing fibers. Instead, it directly wraps basalt fiber reinforcing fibers on the mandrel to form an inner lining layer and directly performs the extrusion and pultrusion winding step. Other operations are the same as in Embodiment 1 to obtain a polyurethane wound pultruded pipe, which serves as the comparative product 4.

[0063] Example 6: The dispensing box does not have a guide bracket.

[0064] The high-strength polyurethane wound pultruded pipe for railway cable crossing prepared in this embodiment has the same outer surface and inner diameter as in Example 1. Its reinforcing fiber content accounts for 82% of the total weight of the pipe. However, during the pultrusion winding, there is no guide support in the injection box. Other operations are the same as in Example 1. A polyurethane wound pultruded pipe is obtained as comparative product 5.

[0065] Example of effect 1

[0066] This embodiment examines the performance of the polyurethane spiral pultruded pipes prepared in Examples 1-6. The tested parameters include tensile strength, tensile strength after immersion in water, flexural strength, Barcol hardness, ring stiffness, drop hammer impact, thermal rim shape, and oxygen index. The specific results are shown in Table 1.

[0067] Table 1. Performance test results of various polyurethane spiral wound pultruded pipes

[0068]

[0069] As shown in the table above, the three types of rail-crossing pipes in Examples 1 and 2 exhibit good compressive strength, twice that of cast iron and 6-8 times that of ordinary SMC materials. Comparing Examples 1, 2, and 3, when the fiber content is below 75% and above 82%, their tensile strength, tensile strength after immersion in water, flexural strength, ring stiffness, Barcol hardness, and hot-edge shape all meet the requirements for rail-crossing pipes. However, when subjected to a drop hammer impact (1.5t), cracks and fissures appear. Given the construction and application environments of rail-crossing pipes, they inevitably experience impacts, making them unsuitable for use as rail-crossing pipes. The reason for this may be that when the fiber content is below 75%, the pipe's supporting strength is insufficient, while when the fiber content is above 82%, the polyurethane component in the pipe is relatively reduced, making it difficult to form a suitable cross-linking system, resulting in a more fragile pipe wall and cracking under impact. Furthermore, a fiber content above 82% also increases the oxygen index, posing a flammability risk and further making them unsuitable for use as rail-crossing pipes.

[0070] Comparing Examples 1 and 4 and 6, it can be seen that the absence of pads and guide supports leads to obvious delamination of the tube body. This indicates that the support of the pads moves the winding fibers inward, allowing them to be well wrapped in polyurethane, eliminating the need for an inner lining layer (or, in other words, the inner lining layer and the tube body are integrally formed), thus giving it good integrity. The guide supports disperse the reinforcing fibers, providing good impregnation space for full impregnation, resulting in good compatibility between the fibers and the polyurethane, tight bonding, and improved tube strength.

[0071] Furthermore, comparing Examples 1 and 5, it can be seen that, except for the oxygen index, the axial fibers affect all aspects of the overall pipe strength, particularly the tensile strength, flexural strength, ring stiffness, and thermal deformation after immersion in water. This is because the axial fibers, together with the polyester felt, enhance the circumferential and flexural strength of the pipe, thereby increasing its shear strength under bending, which is obvious. The axial fibers passing through the polyester felt also enhance the constraint of the reinforcing fiber bundles in the pipe to a certain extent, keeping the fibers in situ or reducing their deformation during immersion in water and under thermal stress, thus adapting to the environment of the pipeline.

[0072] Example 2

[0073] Stress analysis software such as ANSYS finite element analysis, Abaqus, or Fluent can be used to analyze the stress intensity of the rail-crossing pipe described in Example 1, where the reinforcing fiber content accounts for 82% of the total pipe weight. The results are as follows: Figures 4 to 9 As shown, under equivalent (Von Mises Stress) pressure ( Figure 5The pipeline has relatively few hazardous areas, existing only on the upper and lower sides, especially the upper side. This also reflects the environmental challenges faced by the pipeline and the ability of the pipeline of this invention to withstand such environments. (Minimum principal stress and maximum principal stress analysis...) Figure 6 and Figure 7 It can be seen that the tube body of the present invention has good resistance to external forces and deformation. Figure 8 Equivalent elastic strain and Figure 9 The total deformation analysis also proves that it has good resistance to deformation and deformation recovery ability.

[0074] Overall, this invention is the first to use polyurethane spiral pultruded pipe as a railway cable crossing pipe, with the reinforcing fiber content accounting for 75-82% of the total pipe weight, effectively ensuring the strength requirements of the polyurethane pipe as a railway cable crossing pipe; and through process improvement, its axial fiber support is increased and the polyurethane component impregnation is improved to ensure the pipe body's stress resistance, ensuring its adaptability to underground crossing environments and service life.

[0075] By employing spacer blocks to assist in the mandrel and mold forming of the pipe, the mandrel is inserted into the mold cavity, and spacer blocks are placed between the mandrel and the mold to form a space within the pipe wall. Reinforcing fibers are arranged using polyester felt, eliminating the need for an inner liner or lining layer. This results in higher overall pipe integrity, solves the problem of delamination cracks, and enhances pipe strength and performance. The use of polyester felt allows for the arbitrary arrangement of reinforcing fibers according to the designed strength and location, increasing the axial fiber density and lateral strength of the pipe, improving its pressure resistance, and ensuring the safety of cables in the pipeline. The injection box has a guide bracket inside, allowing the reinforcing fibers to form space for rapid polyurethane impregnation. Furthermore, multi-directional injection avoids resin reaction and mold blockage before curing when using multiple injection boxes, improving production efficiency and ensuring product quality.

[0076] Furthermore, the rail-crossing pipe of this invention has a low specific gravity, making transportation and installation convenient; it is also impact- and corrosion-resistant, able to withstand some collisions and frictions unavoidable during production, and can be used in special environments such as acidic and alkaline environments and coastal environments; it also has good insulation properties, avoiding the hazards caused by conductivity when used as a rail-crossing pipe for railway cables. Professional testing has shown that its compressive strength is twice that of cast iron and 6-8 times that of ordinary SMC materials, meeting the long-life design requirements for rail-crossing pipes. Moreover, the rail-crossing pipe of this invention can be segmented and connected by designing water guide channels and connecting elbows, and led out to the ground using 45-degree elbows, replacing manholes, which is beneficial for branch cable transfer, installation, and drainage, and has good practical value and application prospects.

[0077] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and not restrictive in all respects. Furthermore, it should be understood that although this specification describes embodiments, it does not encompass only one technical solution. This descriptive method is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method of manufacturing a railway cable crossing pipe, characterized by: Specifically comprising the following steps: 1) mold assembly: the mandrel is inserted into the cavity of the rail pipe forming mold shell, and the position of the mandrel is adjusted at the center of the cavity of the forming mold shell by the cushion block; 2) preparation of glue solution: prepare two-component thermosetting polyurethane resin, including resin A and resin B; the components of the resin A include urethane, ether, urea, urethane and internal release agent; the resin B contains diphenylmethane diisocyanate; and the mass ratio of resin A and resin B is 105-108:100; 3) adjusting the mandrel: adjust the fixed end of the mandrel to fix its relative position with the pipe forming mold shell; 4) yarn cloth distribution: cut the polyester felt into appropriate size according to the cross-sectional view of the rail pipe, and position it at the predetermined position by the felt guide; then arrange the distribution of the reinforcing fiber bundle according to the cross-sectional view of the rail pipe; 5) fiber threading: mark several areas on the threading plate according to the design, thread the basalt fiber into the corresponding holes of the yarn collecting plate according to the designed number, and guide and lead out through the guide bracket in the glue injection box; 6) pultrusion and winding: heat the forming mold, control the temperature of the inlet, middle and outlet of the mold, and at the same time, inject the prepared resin A glue solution and resin B glue solution into the corresponding glue barrels; after the temperature of the forming mold is stable, open the pultrusion equipment, winding equipment and glue injection machine at the same time, and according to the set glue injection pressure and proportion, carry out glue injection and impregnation, according to the set traction speed, carry out pultrusion, and adjust the number of winding reinforcing fiber layers according to the traction speed; After the glue injection and impregnation are cured, the high-strength railway cable rail pipe is obtained.

2. The method of claim 1, wherein: The preparation method uses a glue injection box for preparation. In step 5), the glue injection box includes a glue injection box body, and an injection cavity is arranged in the glue injection box body and communicates with the cavity of the forming mold shell; a plurality of guide brackets are arranged in the injection cavity to separate the injection cavity to form a plurality of impregnation spaces for impregnating the reinforcing fiber bundle; a plurality of glue injection holes are arranged on the guide bracket; a plurality of glue injection holes are arranged on the glue injection box body; the glue injection holes are distributed on the side wall of the glue injection box body and located between the two guide brackets or between the guide bracket and the side wall of the glue injection box body.

3. The method of claim 1, wherein: In step 6), the temperature of the inlet, middle and outlet of the forming mold is controlled to be 100-120℃, 130-150℃ and 150-170℃ respectively; the temperature of the glue injection is 20-25℃, and the pressure is 1.5-2.5Mpa; the traction speed is 0.35-0.5m per minute; and the number of winding reinforcing fiber layers is 1 layer in positive and negative directions.

4. The method of claim 1, wherein: The forming mold includes a mandrel, a forming mold shell and a cushion block; the outer dimensions of the mandrel are the same as the hole type and size of the rail pipe inner hole, the mandrel penetrates the forming mold shell, and the mandrel is positioned at the central axis of the cavity of the forming mold shell by the cushion block; the inner cavity of the forming mold shell is polygonal, and the cavity wall is provided with protruding water tank forming strips.

5. The method of claim 4, wherein: The core rod and the forming mold shell are made of Cr 12 The core rod is positioned on the central axis of the cavity of the forming mold shell, and the cushion block is made of 45 steel and is distributed on the upper and lower sides of the two traction clamps at the two ends of the forming mold shell, and the thickness of the cushion block is consistent with the wall thickness of the railway cable over-rail pipeline.

6. A railway cable tube, characterized by: The rail-penetrating pipeline is a polyurethane winding pultrusion pipeline prepared by the preparation method according to any one of claims 1-5, and has a main body made of thermosetting polyurethane injection molding, winding reinforcing fiber bodies, longitudinal reinforcing fiber bodies and mesh reinforcing partitions distributed in the main body; and the content of the winding reinforcing fiber bodies, the longitudinal reinforcing fiber bodies and the mesh reinforcing partitions accounts for 75-82% of the total weight of the rail-penetrating pipeline.

7. The railway cable routing tube of claim 6, wherein: The winding reinforcing fiber bodies are formed by bidirectional winding of reinforcing fiber bundles around the pipeline in multiple layers along the axial direction of the pipeline; the mesh reinforcing partitions are distributed in the pipeline wall of the rail-penetrating pipeline at equal intervals along the axial direction of the pipeline; and the longitudinal reinforcing fiber bodies are formed by distributing reinforcing fiber bundles in the pipeline wall along the axial direction of the pipeline.

8. The railway cable routing tube of claim 7, wherein: The reinforcing fiber bundles of the winding reinforcing fiber bodies and the reinforcing fiber bundles of the longitudinal reinforcing fiber bodies are both made of basalt fibers, and the mesh reinforcing partitions are made of polyester felt, which has a shape consistent with the cross section of the rail-penetrating pipeline and an area smaller than the cross section area of the rail-penetrating pipeline.

9. The railway cable routing tube of claim 6, wherein: The cross section outer wall is a polygon, and the outer wall is provided with water guide grooves recessed towards the inner wall.

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