Trenchless modified polypropylene cable conduit and preparation process thereof

Abstract

The invention discloses a trenchless modified polypropylene cable conduit and a preparation process thereof, and relates to the field of cable conduits.The trenchless modified polypropylene cable conduit comprises a conduit body and end cover parts installed at openings in the two ends of the conduit body, each end cover part is internally provided with a partition assembly used for cable partition, and the conduit body further comprises an outer pipe layer and an inner pipe layer; a plurality of compression-resistant supporting strips are distributed, wound and fixed on the end face of the outer side of the inner pipe layer, a heat dissipation gap area is formed between every two adjacent compression-resistant supporting strips and the outer pipe layer, and heat dissipation openings are formed in the end cover parts in a penetrating mode and communicate with the heat dissipation gap areas correspondingly. Through the collaborative design of an innovative double-layer co-extrusion structure, an active heat dissipation channel formed by built-in compression-resistant supporting strips and communication with heat dissipation openings of the end covers, the ring stiffness and the heat dissipation efficiency of the guide pipe are remarkably improved, and the compression resistance, the heat dissipation stability and the long-term operation reliability of the guide pipe in a complex burial depth environment are comprehensively enhanced.

Description

Technical Field

[0001] This invention relates to the field of cable conduits, specifically to a trenchless modified polypropylene cable conduit and its manufacturing process. Background Technology

[0002] With the acceleration of urban modernization, underground power cable installation has become a core part of urban infrastructure construction. Trenchless technology, with its outstanding advantage of minimal impact on ground traffic and the environment, is widely used in such projects. Modified polypropylene (MPP) power conduits, due to their excellent electrical insulation, corrosion resistance, high temperature resistance, and ease of construction, have become one of the preferred conduits for trenchless cable laying.

[0003] However, traditional single-layer MPP conduits have long faced several technical bottlenecks in practical applications: First, their structural design often struggles to simultaneously balance the low friction coefficient of the inner wall and the high ring stiffness of the pipe body. In pursuit of convenient laying, an excessively smooth inner wall sacrifices wall thickness and material strength, resulting in insufficient resistance to soil and ground load pressure. This poses a risk of pipe deformation, especially when laid in roadways or deep underground. Moreover, in some areas, increased rainfall and higher soil moisture content can significantly increase the pressure on the pipeline.

[0004] Secondly, and most critically, the problem lies in heat dissipation defects. Cables generate heat during operation. Traditional MPP conduits, as relatively closed systems, lack effective active heat dissipation channels. Heat accumulates inside the conduit, forming a "heat reservoir effect," causing the cable operating temperature to rise continuously. This not only increases the resistance and power loss of the cable line but also accelerates the aging of the cable insulation material, shortens its service life, and may even cause electrical faults, becoming a hidden danger to the safe operation of the power grid. Summary of the Invention

[0005] The purpose of this invention is to provide a modified polypropylene cable conduit for trenchless construction and its preparation process, which can meet the high strength requirements of trenchless construction and effectively solve the heat dissipation problem of cable operation, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a modified polypropylene cable conduit for trenchless installation, comprising a conduit body and end caps installed at the openings at both ends of the conduit body. Each end cap is provided with a partitioning component for cable partitioning. The conduit body further comprises an outer tube layer and an inner tube layer. Several pressure-resistant support strips are distributed and fixedly wound on the outer end face of the inner tube layer. A heat dissipation gap area is formed between two adjacent pressure-resistant support strips and the outer tube layer. Ventilation holes are distributed in each heat dissipation gap area of ​​the inner tube layer. A heat dissipation vent is provided through the end cap, and the heat dissipation vent is interconnected with the heat dissipation gap area.

[0007] Preferably, the partitioning component includes a central ring body and several crossbars. Each crossbar is fixedly connected between the central ring body and the end cap. Adjacent crossbars form partitioned areas. Sliding grooves are provided on both end faces of the crossbars. A slider is slidably installed in each sliding groove. A pressure rod is rotatably installed on the slider. Two pressure rods located in the same partitioned area are staggered front and rear. A locking head is installed between the two pressure rods.

[0008] Preferably, the outer end face of the inner tube layer is provided with an inner groove, and the pressure-resistant support strip is fixedly embedded in the inner groove.

[0009] Preferably, a middle tube is fixedly installed between the two middle ring bodies.

[0010] Furthermore, the present invention also provides a process for preparing a trenchless modified polypropylene cable conduit, comprising the following steps:

[0011] S1: Raw material pretreatment: Weigh 50-60 parts by weight of polypropylene matrix, 10-15 parts by weight of talc, 5-8 parts by weight of polyolefin elastomer, 3-5 parts by weight of precipitated silica, 2-5 parts by weight of polar polymer, 0.5-2 parts by weight of antioxidant and 3-5 parts by weight of modifier. After being mixed evenly in a high-speed mixer, the mixture is melt-blended at 180-220℃ through a twin-screw extruder to obtain modified polypropylene material.

[0012] S2: Forming the conduit body. The modified polypropylene material obtained is fed into a double-layer co-extrusion extruder and extruded using a double-layer co-extrusion die with a built-in forming module. The forming module is used to integrally extrude an axially extending inner groove on the outer end face of the inner tube layer of the conduit body and integrally form a vent hole at the position corresponding to the heat dissipation gap area.

[0013] S3: Installation of compression support strip: The high-strength polypropylene composite compression support strip, which is pre-molded by injection molding, is embedded into the inner groove formed in step S2, and is firmly connected to the inner tube layer by hot melt bonding or mechanical fixing.

[0014] S4: End cap manufacturing: The same modified polypropylene material as in step S1 is used to form the end cap by injection molding, and a heat dissipation port corresponding to the position of the vent hole is provided through the end cap.

[0015] S5: Assemble the whole assembly by installing the end caps at the openings at both ends of the duct body, ensuring that the heat dissipation vents are connected to the ventilation holes to form a complete heat dissipation duct.

[0016] Preferably, in step S2, the inner layer of the double-layer co-extrusion process uses the modified polypropylene material, and the outer layer uses a modified polypropylene reinforcing material with 5% glass fiber added, with the co-extrusion temperature controlled at 190-210℃.

[0017] Preferably, the method for preparing the compressive support strip in step S3 includes the following steps:

[0018] Step 1: Raw material preparation and pretreatment: Weigh 70-80 parts by weight of polypropylene base material, 3-5 parts by weight of compatibilizer, 0.5-1 parts by weight of nucleating agent, 0.2-0.5 parts by weight of antioxidant and 0.5-1 parts by weight of lubricant, put them into a high-speed mixer and mix evenly to obtain premix;

[0019] Step 2: Preparation of glass fiber reinforced masterbatch: The premix obtained in Step 1 is added from the main feed port of the twin-screw extruder, and 20-30 parts of chopped glass fiber are quantitatively added to the screw melting section through a side feeder; after melt blending, extrusion, cooling, and pelletizing, glass fiber reinforced polypropylene masterbatch is obtained, wherein the melt blending temperature is controlled at 180-210℃;

[0020] Step 3: Injection molding. After drying the masterbatch obtained in step 2, it is put into the injection molding machine and injected into the pre-designed mold cavity of the compression support strip. After holding pressure and cooling, it is ejected to obtain a compression support strip with a specific cross-sectional shape.

[0021] Preferably, the process parameters of the injection molding machine in step three are set as follows: barrel temperature 190-210℃, mold temperature 50-70℃, and injection pressure 80-100MPa.

[0022] Preferably, the polar polymer is maleic anhydride-grafted polypropylene or ethylene-acrylic acid copolymer.

[0023] Preferably, in step S2, the diameter of the vent holes is 0.5-1.0 mm and the spacing between the holes is 2-3 mm.

[0024] In summary, the beneficial effects of this invention are:

[0025] This invention significantly improves the ring stiffness and heat dissipation efficiency of the conduit through an innovative double-layer co-extrusion structure, an active heat dissipation channel formed by built-in anti-compression support strips, and a collaborative design that connects with the heat dissipation vents of the end caps. Combined with flexibly adjustable partition components, it achieves scientific separation and fixation of the cable, avoids heat accumulation, extends the cable's service life by more than 30%, comprehensively enhances its compressive strength, heat dissipation stability, and long-term operational reliability in complex burial environments, and greatly improves the safety and economy of trenchless cable laying projects. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of a trenchless modified polypropylene cable conduit according to the present invention.

[0028] Figure 2 This is a top view schematic diagram of a trenchless modified polypropylene cable conduit according to the present invention.

[0029] Figure 3 This is a schematic diagram showing the structure at the port of a trenchless modified polypropylene cable conduit according to the present invention.

[0030] Figure 4 This is a schematic diagram of the partitioned component structure of a trenchless modified polypropylene cable conduit according to the present invention.

[0031] Figure 5 This is a schematic diagram of the manufacturing process of a trenchless modified polypropylene cable conduit according to the present invention.

[0032] Figure 6 This is a schematic diagram of the preparation process of the compressive support strip in the preparation process of a trenchless modified polypropylene cable conduit of the present invention.

[0033] The markings in the attached diagram are described as follows: 1. Conduit body; 2. End cap; 3. Partition assembly; 10. Outer tube layer; 11. Inner tube layer; 12. Pressure-resistant support bar; 13. Inner groove; 14. Heat dissipation gap area; 21. Heat dissipation port; 30. Horizontal bar; 31. Middle ring body; 32. Sliding groove; 33. Sliding block; 34. Pressure rod; 35. Locking head; 36. Middle cylinder tube. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0035] To facilitate understanding of the present invention, a more complete description of the invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

[0036] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0037] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of at least two elements or the interaction relationship of at least two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] Please see Figures 1-4 This invention provides an embodiment of a trenchless modified polypropylene cable conduit, comprising a conduit body 1 and end caps 2 installed at the openings at both ends of the conduit body 1. Each end cap 2 is provided with a partitioning component 3 for cable partitioning. The conduit body 1 also includes an outer tube layer 10 and an inner tube layer 11. This double-layer structure design achieves an optimized combination of material properties. The inner tube layer 11, as the direct contact layer for the cable, can be designed with a smooth inner wall to reduce cable laying resistance. The outer tube layer 10 provides structural strength and external protection. Compared with traditional single-layer MPP pipes, this design can better balance the smoothness of the inner wall and the strength of the external structure, meeting the characteristic of a 40% reduction in cable laying resistance.

[0040] Several pressure-resistant support strips 12 are wound and fixedly distributed on the outer end face of the inner tube layer 11. An inner groove 13 is provided on the outer end face of the inner tube layer 11, and the pressure-resistant support strips 12 are fixedly embedded in the inner groove 13. A heat dissipation gap area 14 is formed between two adjacent pressure-resistant support strips 12 and the outer tube layer 10. Ventilation holes are distributed in each of the heat dissipation gap areas 14 of the inner tube layer 11. The pressure-resistant support strips 12 are fixedly embedded in the inner groove 13, forming a uniformly distributed support structure, while simultaneously forming a heat dissipation gap area 14 between the inner tube layer 11 and the outer tube layer 10. This design improves pressure resistance while... At the same time, an active heat dissipation channel is created. A heat dissipation port 21 is provided through the end cap 2. The heat dissipation port 21 is connected to the heat dissipation gap area 14. The heat dissipation port 21 and the heat dissipation gap area 14 are connected to form a complete heat dissipation channel. Although traditional MPP power pipes have good temperature resistance, they lack active heat dissipation design. This design can effectively reduce the operating temperature of the cable and extend the service life of the cable by combining vent holes and heat dissipation ports. It can also avoid the risk of insulation performance degradation and failure due to overheating. Even if the cable conduit needs to be extended, the heat dissipation ports 21 can be aligned to form a long channel for heat dissipation.

[0041] It is worth mentioning that, in this embodiment, the partitioning component 3 includes a central ring body 31 and several horizontal blocks 30. Each horizontal block 30 is fixedly connected between the central ring body 31 and the end cap 2. A partition area is formed between two adjacent horizontal blocks 30. The partition area is formed by the combination of the horizontal blocks 30 and the central ring body 31. An independent cable partition space is formed between adjacent horizontal blocks 30. Compared with the design of simple cable bundling or single channel in traditional conduits, this design realizes precise cable partitioning management. It can scientifically separate cables according to different voltage levels, uses or functions. In the complex underground pipe network of the city, this partitioning management makes the cable system clearer and more orderly, and greatly improves maintenance efficiency and safety.

[0042] The crossbar 30 has a sliding groove 32 on each of its two end faces. A slider 33 is slidably installed in each sliding groove 32. A pressure rod 34 is rotatably installed on the slider 33. Two pressure rods 34 located in the same partition area are staggered front to back. A locking head 35 is installed between the two pressure rods 34. A middle cylinder tube 36 is fixedly installed between the two middle rings 31. The design of the sliding groove 32 and the slider 33 allows the pressure rod 34 to be flexibly adjusted. The two pressure rods 34 are staggered front to back and fixed by the locking head 35. The staggered pressure rods 34 form a clamp, which is more secure and reliable than the traditional single-point fixing. The sliding design of the slider 33 allows the pressure rod 34 to automatically adjust the clamping position according to the cable diameter. The locking head 35 ensures the stability of the partition and prevents the cable from shifting during operation.

[0043] The partitioned areas and the heat dissipation gap area 14 of the conduit, along with the vent holes, form a coordinated heat dissipation system.

[0044] The partitioned areas provide air circulation channels between cables, forming a continuous heat dissipation path with the heat dissipation gap area 14 of the conduit. The appropriate spacing between cables reduces heat transfer between cables, avoiding the overheating problem of traditional densely arranged cables. It complements the overall heat dissipation design of the conduit, making the cable operating temperature more stable. Traditional MPP conduits lack heat dissipation design between cables, which makes the cables prone to insulation aging in high-temperature environments. This design effectively extends the service life of the cables through the synergy of partitioning and heat dissipation system.

[0045] In addition, refer to Figures 5-6 The present invention also provides a process for preparing a trenchless modified polypropylene cable conduit, comprising the following steps:

[0046] Step 1: Raw material pretreatment. Weigh 50-60 parts by weight of polypropylene matrix, 10-15 parts by weight of talc, 5-8 parts by weight of polyolefin elastomer, 3-5 parts by weight of precipitated silica, 2-5 parts by weight of polar polymer, 0.5-2 parts by weight of antioxidant and 3-5 parts by weight of modifier. After mixing evenly in a high-speed mixer, melt blend the mixture through a twin-screw extruder at 180-220℃ to obtain modified polypropylene material.

[0047] Specifically:

[0048] Polypropylene matrix, isotactic polypropylene, melt index 20 g / 10 min;

[0049] Talc powder, particle size 2μm, surface modified;

[0050] Polyolefin elastomer, POE-8100, ethylene-octene copolymer;

[0051] Precipitated silica, specific surface area 150 m² / g;

[0052] Polar polymer, maleic anhydride-grafted polypropylene (MAPP).

[0053] Antioxidant, 1010+168 compound antioxidant;

[0054] Modifier, nano-spherical Al2O3 grafted palm fiber abrasion resistant agent;

[0055] Polypropylene matrix, talc, polyolefin elastomer, precipitated silica, polar polymer, antioxidant and modifier are put into a high-speed mixer. The mixing temperature is controlled at 80℃ and the mixing time is 10 minutes to ensure uniform dispersion of materials. The mixed material is fed into a twin-screw extruder. The melt blending temperature is set at 200℃ and the extruder screw speed is controlled at 100 r / min. After extrusion and granulation, the material is cooled to room temperature to obtain modified polypropylene granules.

[0056] Step 2: Forming the main body of the conduit. The modified polypropylene material obtained is fed into a double-layer co-extrusion extruder and extruded using a double-layer co-extrusion mold with a built-in forming module. The forming module is used to integrally extrude an axially extending inner groove on the outer end face of the inner tube layer of the main body of the conduit and integrally form a vent hole at the position corresponding to the heat dissipation gap area.

[0057] Specifically, the modified polypropylene granules obtained in the first step are fed into a double-layer co-extrusion extruder. The inner layer uses modified polypropylene material, and the outer layer uses modified polypropylene reinforcing material with 5% glass fiber added (glass fiber content 5%). The co-extrusion temperature is set to 200℃, the inner layer temperature is 195℃, and the outer layer temperature is 205℃. The double-layer co-extrusion die with built-in molding module is used for extrusion molding. An axially extending inner groove (3mm wide and 2mm deep) is integrally extruded on the outer end face of the inner tube layer. Ventilation holes (0.8mm in diameter and 2.5mm in spacing) are integrally formed at the corresponding heat dissipation gap area. The extrusion speed is controlled at 1.5m / min to ensure product dimensional stability.

[0058] The third step is the installation of the compression support strips.

[0059] Specifically, Step 1: Raw material preparation and pretreatment: Weigh 70-80 parts by weight of polypropylene base material, 3-5 parts by weight of compatibilizer, 0.5-1 parts by weight of nucleating agent, 0.2-0.5 parts by weight of antioxidant and 0.5-1 parts by weight of lubricant, put them into a high-speed mixer and mix evenly to obtain premixed material;

[0060] The polypropylene base material is isotactic polypropylene with a melt index of 25 g / 10 min.

[0061] The compatibilizer is ethylene-acrylic acid copolymer (EAA);

[0062] The nucleating agent is a β-nucleating agent (N-phenyl-2-benzimidazole thioacetamide).

[0063] The antioxidant is 1010 antioxidant;

[0064] The lubricant is calcium stearate;

[0065] The chopped glass fibers are 12 mm in length and 10 μm in diameter.

[0066] Step 2: Preparation of glass fiber reinforced masterbatch: The premix obtained in Step 1 is added from the main feed port of the twin-screw extruder, and 20-30 parts of chopped glass fiber are quantitatively added to the screw melting section through a side feeder; after melt blending, extrusion, cooling, and pelletizing, glass fiber reinforced polypropylene masterbatch is obtained, wherein the melt blending temperature is controlled at 180-210℃;

[0067] Step 3: Injection molding. After drying the masterbatch obtained in Step 2, it is put into the injection molding machine. Under the process parameters of barrel temperature 190-210℃, mold temperature 50-70℃, and injection pressure 80-100MPa, it is injected into the pre-designed mold cavity of the compression support strip. The holding time is 15 seconds and the cooling time is 30 seconds. After ejection, a compression support strip with a specific cross-sectional shape (cross-sectional size: 3mm×2mm) is obtained. The compression support strip is embedded in the formed inner groove and fixed by hot melt bonding (hot melt temperature 210℃, bonding time 30 seconds).

[0068] Step 3: Manufacturing the end cap.

[0069] Using the same modified polypropylene material as in the first step, an end cap is formed by injection molding, and a heat dissipation port corresponding to the position of the vent hole is provided through the end cap.

[0070] Specifically, the material is fed into the injection molding machine, the barrel temperature is 200℃, the mold temperature is 60℃, the injection pressure is 90MPa, and the end cap is injection molded. Ensure that a heat dissipation port (0.8mm in diameter, aligned with the vent hole) is provided on the end cap to correspond to the position of the vent hole. The end cap is then connected to the openings at both ends of the guide tube body by hot melt bonding.

[0071] Step 4: Overall Assembly

[0072] Install the end caps at both ends onto the openings at both ends of the duct body, ensuring that the heat dissipation vents and vent holes are precisely aligned to form a complete heat dissipation air duct. Check the connectivity of the heat dissipation air duct to ensure there is no blockage. Perform quality testing on the product: ring stiffness ≥30kN / m², limiting oxygen index ≥37%, and mass wear ≤3.8mg.

[0073] In summary, this invention achieves high ring stiffness (31.2 kN / m²) and high heat dissipation performance (15.2% heat dissipation efficiency) of the conduit body through a deep integration of innovative double-layer co-extrusion process (inner layer using modified polypropylene material, outer layer with 5% glass fiber) and structural design. The glass fiber reinforced compression support strips (ensuring uniform distribution through masterbatch preparation) are precisely embedded in the inner groove, forming a complete heat dissipation channel in conjunction with 0.8mm diameter, 2.5mm spacing vent holes on the inner tube layer and heat dissipation vents on the end cap. Simultaneously, the groove-slider-pressure rod structure of the partitioned components, precisely injection molded (barrel temperature 200℃, mold temperature 60℃), enables scientific partitioned management of the cable. Working synergistically with the heat dissipation system, this reduces the cable operating temperature by 12℃ and extends its service life by more than 30%, significantly improving the efficiency, safety, and overall life-cycle economics of trenchless construction.

[0074] In practical application, consider the following scenario: To facilitate the construction of a new district, a city needs to expand the power supply to a main road running through its city center. The newly laid cable is a 10kV medium-voltage cable, approximately 2 kilometers long. Due to its location in the city center, heavy traffic, and extremely complex underground pipeline network (dense water, gas, and communication lines), it was decided to use trenchless technology (directional drilling) for construction. The project route will pass through different geological areas, and the impact of the local rainy season must be considered.

[0075] Scenario 1: Shallow laying (burial depth 1.2 meters)

[0076] This depth is located below the sidewalk and green belt, and is greatly affected by ground temperature fluctuations and weather.

[0077] No rain (sunny summer day, ambient temperature 35℃):

[0078] Traditional MPP pipes: When cables are energized, they generate heat. Due to their single-layer structure and the lack of partitioning within the pipe, heat accumulates significantly. Actual measurements show that the surface temperature of the cable inside the pipe can reach 75°C. Prolonged operation at this temperature accelerates the aging of the cable insulation, posing safety hazards. Heat dissipation relies entirely on slow heat conduction through the soil, resulting in low efficiency.

[0079] The catheter of this invention:

[0080] Zoned heat dissipation: The cables are precisely separated and fixed by the crossbars and pressure bars, with air channels between them to avoid the concentrated accumulation of heat.

[0081] Active heat dissipation: After the cable heats up, the heat enters the heat dissipation gap 14 through the vent holes. Due to the shallow burial depth, the temperature difference between the ground and the inside of the pipe creates a weak airflow (chimney effect). The hot air is slowly discharged through the heat dissipation port 21 of the end cap, while cooler external air is drawn in, forming a continuous gas exchange.

[0082] Results: Under the same operating conditions, the cable surface temperature remained stable at 58℃. Compared with traditional pipelines, the cable operating temperature was reduced by 17℃, which not only significantly extended the cable life but also improved the power transmission efficiency (conductor resistance increases with temperature).

[0083] Rainfall conditions (summer downpours):

[0084] Traditional MPP pipes: Rainwater seeps into the soil, increasing the soil's thermal conductivity and carrying away some heat to a certain extent. However, once the soil becomes saturated with water, water accumulation can easily form, and prolonged immersion poses a challenge to the sealing of pipe joints and the lifespan of the materials.

[0085] The catheter of this invention:

[0086] Maintaining heat dissipation advantages: The soil cooling effect brought by rainwater can also be transmitted through the pipe wall. At the same time, the heat dissipation gap 14 is a closed air layer isolated from the soil, and its active heat dissipation channel is not affected by soil moisture and can still operate effectively.

[0087] Scenario 2: Intermediate layer laying (burial depth 3.0 meters)

[0088] This pipeline passes beneath a main road at this depth and bears the dynamic load of ground vehicles, requiring high compressive strength.

[0089] No rain:

[0090] Traditional MPP pipes: Soil temperature is stable, but heat dissipation is more difficult. The heat of the cable is tightly wrapped, forming a "heat reservoir" effect, and the temperature can reach above 80°C, making it a high-incidence area for cable failures.

[0091] The catheter of this invention:

[0092] Structural advantages: The pressure-resistant support strip 12 is embedded in the inner groove 13, and together with the outer tube layer 10, it forms an extremely high ring stiffness (≥30kN / m²), perfectly withstanding the pressure of the soil and vehicles above, and preventing the tube from deforming and squeezing the cable.

[0093] Heat dissipation advantages: Even at depth, the "ventilation hole-heat dissipation gap area-heat dissipation port" still constitutes a continuous "long channel heat dissipation system". Although air convection is weakened, this channel becomes an efficient heat conduction path, which quickly conducts the heat generated by the cable to a longer range of the pipe wall, greatly increasing the heat dissipation contact area with the surrounding soil. The measured cable temperature is controlled below 65℃.

[0094] Rainfall conditions:

[0095] Traditional MPP pipes: Due to the slow change in moisture content in deep soil, rainwater has almost no effect on their heat dissipation performance. If their compressive strength is insufficient, they are at risk of being flattened when the soil moisture content increases.

[0096] The conduit of this invention has high ring stiffness, which ensures the stability of the structure in moist soil. The heat dissipation system continues to work effectively by increasing the heat dissipation area, and its performance is not affected by the environment.

[0097] Scenario 3: Deep laying (burial depth below 5.5 meters)

[0098] This depth is used for tunneling under rivers or the foundations of important buildings, where geological conditions may be more complex.

[0099] No rain / Rainy conditions:

[0100] At this depth, the soil temperature is constant, but the pressure is extremely high, and there is almost no weather influence.

[0101] Traditional MPP pipes suffer from extremely serious heat dissipation problems, resulting in long-term high-temperature operation of the cables. The single-layer structure poses a high risk under high voltage.

[0102] The core advantages of this catheter are as follows:

[0103] Exceptional compressive strength: The glass fiber reinforced compressive support bar 12 and double-layer structure design ensure the roundness and structural safety of the pipeline under ultra-deep burial, providing a robust protective enclosure for the cable.

[0104] Stable heat dissipation guarantee: Although the active airflow is weak, the "ventilation hole-heat dissipation gap zone" system forms a "static air insulation layer" around the cable. This air layer not only assists in heat dissipation, but more importantly, it effectively isolates the cold energy of the underground constant temperature layer (usually lower), providing the cable with a more stable operating environment with smaller temperature fluctuations. This avoids the thermal expansion and contraction stress caused by external temperature changes in the cable, which is especially important for ultra-long cable lines.

[0105] The cable conduit of this invention, through its unique double-layer structure, active heat dissipation system, cable partition management and high-strength pressure-resistant design, can provide better safety, reliability, heat dissipation and longer cable life than traditional pipes under different depths and climatic conditions, and is particularly suitable for trenchless cable laying projects in the complex environment of modern cities.

[0106] The above description is merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any variations or substitutions conceived without inventive effort should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A trenchless modified polypropylene cable conduit characterized by: The utility model provides a kind of cable conduit, including conduit body (1) and the end cap portion (2) installed at the opening of the both ends of the conduit body (1), each of the end cap portion (2) is provided with the partition component (3) for cable partition, the conduit body (1) further includes outer tube layer (10) and inner tube layer (11), the outer side end surface of the inner tube layer (11) is distributed and is wound and fixed with several compression support strips (12), the heat dissipation gap area (14) is formed between adjacent two compression support strips (12) and the outer tube layer (10), the inner tube layer (11) is provided with air hole in the region of each heat dissipation gap area (14), the end cap portion (2) is provided with heat dissipation port (21) through, and the heat dissipation port (21) is respectively communicated with the heat dissipation gap area (14) each other.

2. A trenchless modified polypropylene cable conduit according to claim 1, characterized in that: The partition component (3) includes a middle ring body (31) and a plurality of crosspieces (30), each of the crosspieces (30) is fixedly connected between the middle ring body (31) and the end cap portion (2), and a partition region is formed between adjacent two crosspieces (30). The two side end surfaces of each crosspiece (30) are provided with a sliding groove (32) respectively. Each sliding groove (32) is slidably installed with a sliding block (33). The sliding block (33) is rotatably installed with a pressing rod (34). Two pressing rods (34) in the same partition region are arranged in front and back staggered manner. A locking head (35) is installed between the two pressing rods (34).

3. A trenchless modified polypropylene cable conduit according to claim 2, characterized in that: The outer side end surface of the inner tube layer (11) is provided with an inner groove (13), and the compression support strip (12) is fixedly embedded in the inner groove (13).

4. A trenchless modified polypropylene cable conduit according to claim 3, characterized in that: A middle cylinder tube (36) is fixedly installed between two middle ring bodies (31).

5. A process for the preparation of a trenchless modified polypropylene cable conduit, characterized by: The utility model includes the following steps: S1: raw material pretreatment, 50-60 parts by weight of polypropylene matrix, 10-15 parts by weight of talcum powder, 5-8 parts by weight of polyolefin elastomer, 3-5 parts by weight of precipitated white carbon black, 2-5 parts by weight of polar polymer, 0.5-2 parts by weight of antioxidant and 3-5 parts by weight of modifier are weighed, uniformly mixed by high-speed mixer, and then melt blended by double-screw extruder at 180-220 DEG C to obtain modified polypropylene material; S2: conduit body forming, the prepared modified polypropylene material is sent into a double-layer co-extrusion machine, and extrusion forming is carried out by using a double-layer co-extrusion die with a built-in forming module. The forming module is used to integrally extrude an inner groove extending in the axial direction on the outer side end surface of the inner tube layer of the conduit body and integrally form an air hole at a position corresponding to the heat dissipation gap area; S3: compression support strip installation, a high-strength polypropylene composite compression support strip prepared by injection molding in advance is embedded in the inner groove formed in step S2, and the inner tube layer is firmly connected by hot melt bonding or mechanical fixing; S4: end cap portion manufacturing, the same modified polypropylene material as in step S1 is used to prepare the end cap portion by injection molding, and a heat dissipation port corresponding to the position of the air hole is provided through the end cap portion. S5: Assemble the whole, install the end cover part at the opening of the conduit body two ends, ensure that the heat dissipation port is communicated with the air hole, and form a complete heat dissipation air duct.

6. A process for the preparation of a trenchless modified polypropylene cable duct according to claim 5, characterized in that: The inner layer of the double-layer co-extrusion process in the step S2 adopts the modified polypropylene material, and the outer layer adopts the modified polypropylene reinforced material added with 5% glass fiber, and the co-extrusion temperature is controlled at 190-210 DEG C.

7. A process for the preparation of a trenchless modified polypropylene cable duct according to claim 6, characterized in that: The preparation method of the compression-resistant supporting strip in the step S3 comprises the following steps: Step one: raw material preparation and pretreatment: 70-80 parts of polypropylene base material, 3-5 parts of compatibilizer, 0.5-1 part of nucleating agent, 0.2-0.5 part of antioxidant and 0.5-1 part of lubricant are weighed by weight, and are mixed uniformly in a high-speed mixer to obtain a premix; Step two: preparation of glass fiber reinforced master batch: the premix obtained in the step one is added from the main feeding port of a double-screw extruder, and 20-30 parts of chopped glass fiber is quantitatively added to the screw melting section through a side feeder; after melting blending, extrusion, cooling and granulation, a glass fiber reinforced polypropylene master batch is prepared, wherein the melting blending temperature is controlled at 180-210 DEG C. Step three: injection molding, after the master batch prepared in step two is dried, it is put into an injection molding machine, and is injected into a pre-designed compression-resistant supporting strip mold cavity, and after pressure maintaining and cooling, it is ejected to prepare a compression-resistant supporting strip with a specific cross-sectional shape.

8. A process for the preparation of a trenchless modified polypropylene cable duct according to claim 7, characterized in that: The process parameter setting of the injection molding machine in the step three is that the barrel temperature is 190-210 DEG C, the mold temperature is 50-70 DEG C, and the injection pressure is 80-100 MPa.

9. A process for the preparation of a trenchless modified polypropylene cable duct according to claim 8, characterized in that: The polar polymer is maleic anhydride grafted polypropylene or ethylene-acrylic acid copolymer.

10. The process for preparing a trenchless modified polypropylene cable conduit according to claim 5, characterized in that: The diameter of the air hole in the step S2 is 0.5-1.0 mm, and the hole spacing is 2-3 mm.

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