Manufacturing method of mpp cable protection pipe and manufacturing mold of protection pipe

Abstract

The application relates to the technical field of MPP protective pipe manufacturing, and is an MPP cable protective pipe manufacturing method, which comprises the following steps: uniformly mixing the following materials in quality parts: 80-90 parts of polypropylene, 10-15 parts of composite elastomer, 20-25 parts of polypropylene fiber, 10-15 parts of magnesium citrate, 7-9 parts of dihydroxy polydimethylsiloxane, 5-7 parts of methacrylic acid, 6-8 parts of acrylonitrile-butadiene-styrene copolymer, 8-10 parts of liquid polysulfide rubber, 8-10 parts of ethylene-tetrafluoroethylene copolymer and 10-12 parts of acrylic resin to obtain mixed materials; and heating and high-pressure injecting the mixed materials into a forming mold of an MPP pipe forming device to co-extrude the MPP pipe. The prepared MPP protective pipe has the advantages of higher strength and longer service life. The application further provides an MPP protective pipe manufacturing mold.

Description

Technical Field

[0001] This invention relates to the field of manufacturing technology of MPP cable protection pipes (hereinafter referred to as MPP protection pipes), specifically to the manufacturing method of MPP protection pipes and the manufacturing mold of MPP protection pipes. Background Technology

[0002] Patent document CN111363286A, entitled "A Modified MPP Cable Protection Pipe," discloses a modified MPP cable protection pipe comprising the following raw materials by weight: modified acrylic resin, graphene A, carbon black, coupling agent, toughening agent, compatibilizer (3-5 parts), lubricant, antioxidant, nano-calcium carbonate, titanium dioxide, and flame retardant. The resulting MPP cable protection pipe exhibits strong corrosion resistance, low coefficient of friction, heat resistance, and cold resistance. However, its mechanical strength and service life have not yet met ideal requirements, and it cannot satisfy some installation requirements.

[0003] For example, in the patent document with publication number "CN114133672A" and title "A High-Strength and High-Pressure-Resistant MPP Cable Protection Pipe", a high-strength and high-pressure-resistant MPP cable protection pipe is disclosed, which includes the following raw materials by weight: 100-150 parts MPP, 25-40 parts pressure-resistant modifier, nano-calcium carbonate, plasticizer, stabilizer, compatibilizer, toughening agent, etc.; however, its mechanical strength and service life do not meet the ideal requirements and cannot meet some installation requirements. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned shortcomings by providing a method for manufacturing an MPP cable protection pipe with higher strength and longer service life, as well as a mold for manufacturing the MPP protection pipe.

[0005] The technical solution for manufacturing the MPP protective pipe of the present invention is as follows: A method for manufacturing an MPP cable protective pipe involves mixing the following materials in parts by weight: 80-90 parts polypropylene, 10-15 parts composite elastomer, 20-25 parts polypropylene fiber, 10-15 parts magnesium citrate, 7-9 parts dihydroxy polydimethylsiloxane, 5-7 parts methacrylic acid, 6-8 parts acrylonitrile-butadiene-styrene copolymer, 8-10 parts liquid polysulfide rubber, 8-10 parts ethylene-tetrafluoroethylene copolymer, and 10-12 parts acrylic resin to obtain a mixed material. The mixed material is then heated and injected under high pressure into the molding die of an MPP pipe forming device to co-extrude the MPP pipe.

[0006] To elaborate further, the temperature of the mixture during co-extrusion is between 220 and 230°C.

[0007] Furthermore, before the coagulant is applied, the temperature of the mixture is brought up to 240-245°C and held for 30-40 minutes. This process is called the preheating process S1.

[0008] Furthermore, there is a co-extrusion stage following the co-extrusion process. The co-extrusion stage includes a first cooling stage S2 and a second cooling stage S4. The temperature of the first cooling stage S2 reaches between 210 and 220°C. The second cooling stage S3 involves spraying water to cool the temperature down to below 120°C. The duration of the first cooling stage S2 is 20 to 25 seconds, and the duration of the second cooling stage S3 is 40 to 50 seconds.

[0009] Furthermore, between the first and second cooling stages, there is a shrinkage process S3 for the resulting MPP tube. The shrinkage process involves reducing the inner and outer diameters of the MPP tube by 1-1.5%, and this shrinkage process is carried out in the forming mold.

[0010] Furthermore, during the shrinkage process of the MPP tube, lubricant is applied to the inside or outside of the MPP tube to ensure smooth extrusion.

[0011] Furthermore, the lubricant used is a mixture of the following raw materials in parts by weight: 20-22 parts silicone oil, 2-3 parts 100-mesh octadecyl alcohol powder, and 2-3 parts 100-mesh adipic acid powder; when in use, the temperature of the lubricant is equal to the temperature of the plastic tube it contacts.

[0012] Furthermore, the lubricant used also includes 5-7 parts by weight of liquid silicone-modified epoxy resin and 2-3 parts by weight of 100-mesh polyurethane-modified epoxy resin powder.

[0013] The technical solution for the manufacturing mold of MPP pipe of the present invention is implemented as follows: An MPP pipe forming mold includes a mold body, the mold body includes an inner core and an outer shell, the inner core and the outer shell are connected by a connecting bridge at the rear, and there is a forming cavity between the inner core and the outer shell. The forming cavity has a raw material injection port at the rear and a product delivery port at the front. The forming cavity includes a first forming cavity at the rear and a second forming cavity at the front. The injection port is connected to the first forming cavity, the second forming cavity is connected to the delivery port, and the internal diameter of the second forming cavity is reduced by 1-1.5% compared with the internal diameter of the first forming cavity.

[0014] Furthermore, there is a lubricant transfer groove on the inner core between the first molding cavity and the second molding cavity. This transfer groove is an inner transfer groove. There is also an inner cover ring inside the inner transfer groove. There is an inner gap between the inner cover ring and the inner transfer groove through which the lubricant passes. The inner gap leads to the inside of the molding cavity. There is also an inner injection tube inside the inner core that connects to the inner transfer groove. In use, the inner injection tube is connected to a high-pressure lubricant reservoir, which is the first reservoir.

[0015] Furthermore, there is a lubricant transfer groove on the outer shell between the first molding cavity and the second molding cavity. This transfer groove is an outer transfer groove. There is also an outer cover ring inside the outer transfer groove. There is an outer gap between the outer cover ring and the outer transfer groove through which lubricant passes. The outer gap leads to the outside of the molding cavity. There is also an external injection pipe inside the outer shell that connects to the outer transfer groove. In use, the external injection pipe is connected to a high-pressure lubricant reservoir, which is a second reservoir.

[0016] The beneficial effects of this invention are that the manufacturing method and mold of this MPP protective tube have the advantages of producing MPP protective tubes with higher strength and longer service life. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the longitudinal section of the mold for manufacturing the MPP protective tube of the present invention.

[0018] Figure 2 Yes Figure 1 Enlarged diagram of part A in the image.

[0019] Figure 3 yes Figure 1 A schematic diagram of the cross-sectional structure along the B-B direction.

[0020] The components include: 1. Mold body; 2. Inner core; 21. Inner transfer groove; 22. Inner cover ring; 23. Inner gap; 24. Inner injection pipe; 25. First filling groove; 3. Outer shell; 31. Outer transfer groove; 32. Outer cover ring; 33. Outer gap; 34. Outer injection pipe; 35. Second filling groove; 4. Connecting bridge; 5. Molding cavity; 51. Injection port; 52. Delivery port; 53. First molding cavity; 54. Second molding cavity. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0022] Examples 1-6 The table below shows the raw materials for several examples (unit: kilograms). polypropylene 80 90 85 85 85 85 Composite elastomer 10 15 13 13 13 13 Polypropylene fiber 20 25 22 22 22 22 Magnesium citrate 10 15 13 0 13 13 Dihydroxypolydimethylsiloxane 7 9 8 0 8 8 methacrylic acid 5 7 6 6 0 6 Acrylonitrile-butadiene-styrene copolymer, 6 8 7 7 0 7 Liquid polysulfide rubber 8 10 9 9 9 0 Ethylene-tetrafluoroethylene copolymer 8 10 9 9 9 0 acrylic resin 10 12 11 11 11 11 Name of the obtained MPP protection tube First MPP protection tube Second MPP protection tube Third MPP protection tube Fourth MPP protection tube Fifth MPP protection tube Sixth MPP protection tube MPP protective tubes are manufactured according to the following process: the raw materials of each embodiment are mixed to obtain a mixture, the mixture is heated and injected under high pressure into the forming mold of the MPP tube forming device, and the MPP tube is co-extruded; the temperature of the mixture during co-extrusion is between 220 and 230°C.

[0023] Tests showed that the first, second, and third MPP protective tubes had higher strength and longer service life than the comparison documents. For example, an MPP protective tube with an inner diameter of 10 cm and a wall thickness of 5 mm could withstand 120 bends at 100 N without breaking. A 10 cm square sample made of such material could withstand 100 hammer blows at 100 N without breaking, and its expected service life is 30 to 10 years.

[0024] The fourth, fifth, and sixth MPP protective tubes tested showed that they were inferior to the first, second, and third MPP protective tubes in terms of higher strength and service life.

[0025] Example 7 Based on Examples 1-3 above, Example 7 is conducted, with the difference being that Example 7 also includes the following step: before co-extrusion, the temperature of the mixture is raised to between 240-245°C and held for 30-40 minutes; this process is called preheating process S1. This yields a seventh MPP protective tube. Compared to the first, second, and third MPP protective tubes, the seventh MPP protective tube generally exhibits 3-5% higher strength and a 4-7% longer service life.

[0026] Example 8 Based on Examples 1, 2, 3, and 7 above, Example 8 is conducted, with the difference being that Example 8 includes the following additional steps: A coagulation and molding stage follows the co-extrusion process. This stage includes a first cooling stage S2 and a second cooling stage S4. The temperature of the first cooling stage S2 reaches between 210 and 220°C. The second cooling stage S3 involves spraying water to lower the temperature to below 120°C. The duration of the first cooling stage S2 is 20-25 seconds, and the duration of the second cooling stage S3 is 40-50 seconds. This yields an eighth MPP protective tube. Compared to the first, second, third, and seventh MPP protective tubes, the eighth MPP protective tube generally exhibits 1-2% higher strength and a 2-4% longer service life.

[0027] Example 9 Based on the above embodiments 1, 2, 3, 7, and 8, embodiment 9 is carried out. The difference is that embodiment 9 also includes the following step: between the first and second cooling stages, a shrinkage process S3 is performed on the resulting MPP tube. The shrinkage process involves reducing the inner and outer diameters of the MPP tube by 1-1.5%, and this shrinkage process is performed in a forming mold. This yields a ninth MPP protective tube. Compared to the first, second, third, seventh, and eighth MPP protective tubes, the ninth MPP protective tube generally exhibits 1-2% higher strength and a 2-4% longer service life.

[0028] Example 10 Repeat Example 9 above: During the MPP tube shrinkage process, lubricant is applied to the inside or outside of the MPP tube to ensure smooth extrusion. This also results in smoother sidewalls for the produced MPP tubes and smoother product flow from the mold.

[0029] In one embodiment, the lubricant is a mixture of the following raw materials in parts by weight: 20-22 parts silicone oil, 2-3 parts 100-mesh octadecyl alcohol powder, and 2-3 parts 100-mesh adipic acid powder; when in use, the temperature of the lubricant is equal to the temperature of the MPP tube it contacts.

[0030] Example 11 Repeat Example 10 above: The lubricant used also includes the following parts by weight: 5-7 parts of liquid silicone-modified epoxy resin and 2-3 parts of 100-mesh polyurethane-modified epoxy resin powder.

[0031] It also has the advantage of forming a surface layer on the inside and outside of the MPP tube. This surface layer makes the surface of the MPP tube smoother, less prone to cracking, and more resistant to aging.

[0032] Therefore, the present invention also provides a surface agent for forming a surface layer on the surface of an MPP pipe: the surface agent is composed of the following raw materials in parts by weight: 20-22 parts silicone oil, 2-3 parts 100-mesh octadecyl alcohol powder, 2-3 parts 100-mesh adipic acid powder, 5-7 parts organosilicon modified epoxy resin, and 2-3 parts 100-mesh polyurethane modified epoxy resin powder. It also has the ability to form a surface layer on the inside and outside of the MPP tube. This surface layer has the advantages of a smoother surface, less prone to cracking on the surface of the MPP tube, and more resistant to aging. This surface agent also helps the MPP tube to be conveyed out of the mold cavity during the formation of the MPP tube.

[0033] like Figure 1 , 2As shown in Figure 3, an MPP pipe forming mold includes a mold body 1, which includes an inner core 2 and an outer shell 3. The inner core and the outer shell are connected at the rear by a connecting bridge 4. Between the inner core and the outer shell is a forming cavity 5. The forming cavity has a raw material injection port 51 and a product delivery port 52. The forming cavity includes a first forming cavity 53 at the rear and a second forming cavity 54 at the front. The injection port is connected to the first forming cavity, and the second forming cavity is connected to the delivery port. The diameter of the inside of the second forming cavity is reduced by 1-1.5% compared to the diameter of the inside of the first forming cavity.

[0034] In this invention, the injection port is connected to the above-mentioned high-pressure mixture in a molten state, and the mixture is extruded through the molding cavity and shrinks inside the second molding cavity, making the MPP tube more compact, which can improve the bearing strength of the MPP tube and increase its service life.

[0035] The diameter of the second molding cavity is reduced by 1-1.5% compared to the diameter of the first molding cavity. The inner diameter R21 of the second molding cavity is reduced by 1-1.5% compared to the inner diameter R11 of the first molding cavity; and the outer diameter R22 of the second molding cavity is reduced by 1-1.5% compared to the outer diameter R12 of the first molding cavity. Furthermore, there is a lubricant transfer groove on the inner core between the first molding cavity and the second molding cavity. This transfer groove is the inner transfer groove 21. There is also an inner cover ring 22 inside the inner transfer groove. There is an inner gap 23 through which lubricant passes between the inner cover ring and the inner transfer groove. The inner gap leads to the inner side of the molding cavity 5. There is also an inner injection pipe 24 inside the inner core and connected to the inner transfer groove. In use, the inner injection pipe is connected to a high-pressure lubricant reservoir, which is the first reservoir 25.

[0036] The above-described configuration of this invention enables the application of lubricant to the inside of the MPP tube, allowing the lubricant to flow smoothly out of the molding cavity. In use, the inner injection tube is connected to a high-pressure lubricant reservoir. The high-pressure lubricant flows through the inner injection tube 24 into the inner transfer tank, and is applied to the inside of the MPP tube through the inner gap, achieving the effect of lubricating the inside of the MPP tube.

[0037] Furthermore, there is a lubricant transfer groove on the outer shell between the first molding cavity and the second molding cavity. This transfer groove is the outer transfer groove 31. There is also an outer cover ring 32 inside the outer transfer groove. There is an outer gap 33 through which lubricant passes between the outer cover ring and the outer transfer groove. The outer gap leads to the outside of the molding cavity 5. There is also an external injection pipe 34 inside the outer shell and connected to the outer transfer groove. In use, the external injection pipe is connected to a high-pressure lubricant holding tank 35, which is the second holding tank.

[0038] The above-described configuration of this invention enables the application of lubricant to the outside of the MPP tube, allowing the lubricant to flow smoothly out of the molding cavity. In use, the external injection pipe is connected to a high-pressure lubricant reservoir. The high-pressure lubricant flows through the external injection pipe 34 into the external transfer groove 31, and is applied to the outside of the MPP tube through the external gap 33, achieving a lubricating effect on the outside of the MPP tube. This allows the MPP tube to flow smoothly out of the mold.

[0039] Any aspects not covered in this invention can be addressed by those skilled in the art.

[0040] In the description of the embodiments of the present invention, it should be noted that the orientations or positional relationships indicated by terms such as "up," "down," "horizontal," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships commonly used when the product of the invention is in use. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for manufacturing an MPP cable protection pipe, comprising mixing the following materials in parts by weight: 80-90 parts polypropylene, 10-15 parts composite elastomer, 20-25 parts polypropylene fiber, 10-15 parts magnesium citrate, 7-9 parts dihydroxy polydimethylsiloxane, 5-7 parts methacrylic acid, 6-8 parts acrylonitrile-butadiene-styrene copolymer, 8-10 parts liquid polysulfide rubber, 8-10 parts ethylene-tetrafluoroethylene copolymer, and 10-12 parts acrylic resin to obtain a mixed material, heating the mixed material and injecting it under high pressure into the forming mold of an MPP pipe forming device to co-extrude the MPP pipe.

2. The method for manufacturing the MPP cable protection pipe according to claim 1, characterized in that: in Before co-extrusion, the temperature of the mixture is raised to 240-245℃ and held for 30-40 minutes; this process is called preheating process S1. After co-extrusion, there is a coagulation and molding stage, which includes a first cooling stage S2 and a second cooling stage S4. The temperature of the first cooling stage S2 reaches between 210-220℃. The second cooling stage S3 is achieved by spraying water to lower the temperature to below 120℃. The duration of the first cooling stage S2 is 20-25 seconds, and the duration of the second cooling stage S3 is 40-50 seconds.

3. The method for manufacturing the MPP cable protection pipe according to claim 3, characterized in that: in Between the first and second cooling stages, there is a shrinkage process S3 for the resulting MPP tube. The shrinkage process involves reducing the inner and outer diameters of the MPP tube by 1-1.5%, and this shrinkage process is carried out in the forming mold.

4. The method for manufacturing the MPP cable protection pipe according to claim 3, characterized in that: During the shrinkage process of the MPP tube, lubricant is applied to the inside or outside of the MPP tube to ensure smooth extrusion.

5. The method for manufacturing the MPP cable protection pipe according to claim 5, characterized in that: The lubricant used is a mixture of the following raw materials in parts by weight: 20-22 parts silicone oil, 2-3 parts 100-mesh octadecyl alcohol powder, and 2-3 parts 100-mesh adipic acid powder; when in use, the temperature of the lubricant is equal to the temperature of the MPP tube it contacts.

6. The method for manufacturing the MPP cable protection pipe according to claim 5, characterized in that: The lubricant used also includes 5-7 parts by weight of liquid silicone-modified epoxy resin and 2-3 parts by weight of 100-mesh polyurethane-modified epoxy resin powder.

7. An MPP cable conduit forming mold, comprising a mold body, the mold body comprising an inner core and an outer shell, the inner core and the outer shell being connected at a rear by a connecting bridge, the space between the inner core and the outer shell being a forming cavity, the forming cavity having a rear raw material injection port and a front product outlet, the forming cavity comprising a rear first forming cavity and a front second forming cavity, the injection port communicating with the first forming cavity, the second forming cavity communicating with the outlet, the inner diameter of the second forming cavity being 1-1.5% smaller than the inner diameter of the first forming cavity.

8. The MPP cable protection pipe forming mold according to claim 7, characterized in that: There is a lubricant transfer groove on the inner core between the first molding cavity and the second molding cavity. This transfer groove is an inner transfer groove. There is also an inner cover ring inside the inner transfer groove. There is an inner gap between the inner cover ring and the inner transfer groove through which the lubricant passes. The inner gap leads to the inside of the molding cavity. There is also an inner injection tube inside the inner core and connected to the inner transfer groove. In use, the inner injection tube is connected to a high-pressure lubricant reservoir, which is the first reservoir.

9. The MPP cable protection pipe forming mold according to claim 7 or 8, characterized in that: There is a lubricant transfer groove on the outer shell between the first molding cavity and the second molding cavity. This transfer groove is the outer transfer groove. There is also an outer cover ring inside the outer transfer groove. Lubricant passes through an outer gap between the outer cover ring and the outer transfer groove. The outer gap leads to the outside of the molding cavity. There is also an external injection pipe inside the outer shell that connects to the outer transfer groove. In use, the external injection pipe is connected to a high-pressure lubricant reservoir, which is the second reservoir.

10. A surface agent for forming a surface layer on the surface of an MPP cable conduit: the surface agent is a mixture of the following raw materials in parts by weight: 20-22 parts silicone oil, 2-3 parts 100-mesh octadecyl alcohol powder, 2-3 parts 100-mesh adipic acid powder, 5-7 parts silicone-modified epoxy resin, and 2-3 parts 100-mesh polyurethane-modified epoxy resin powder.

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