A process for the production of a natural crosslinked cable and a cable

Abstract

The present disclosure relates to a natural cross-linking cable preparation process and a cable, the natural cross-linking cable preparation process comprising: step one, obtaining a conductor; step two, taking a natural cross-linking raw material to extrude and coat the outer periphery of the conductor to obtain a cross-linking product; step three, taking the obtained cross-linking product to stand and perform natural cross-linking, and obtaining a semi-finished product cable after the natural cross-linking is completed; step four, performing inspection on the semi-finished product cable obtained in step three, and the qualified product is a finished product natural cross-linking cable; and the cable is prepared by using the above natural cross-linking cable preparation process. The present disclosure shortens the production cycle and reduces the production cost by using the natural cross-linking process to perform the insulation extrusion coating of the cable.

Description

Technical Field

[0001] This disclosure relates to the field of cable manufacturing technology, specifically to a natural cross-linked cable manufacturing process. Background Technology

[0002] Currently, the manufacturing process for cable insulation sleeves generally involves the following two methods in the preparation of the insulation material:

[0003] 1. Irradiation crosslinking, such as the production process of a cable insulation sleeve disclosed in patent CN112735707A, which includes heating and mixing the insulation sleeve raw materials, injecting them into an extruder for extrusion molding, irradiating the insulation sleeve with ultraviolet light, and cooling and molding.

[0004] 2. Steam crosslinking, such as the production method of silane crosslinked low smoke halogen-free flame retardant polyolefin cable material disclosed in patent CN111508662B, which mixes the base material and catalyst masterbatch, and after extrusion by a single screw extruder, it needs to be placed in a warm water bath or steam for 6 to 8 hours.

[0005] The above two methods for preparing insulating materials each have the following drawbacks:

[0006] 1. Insulation materials are prepared using the irradiation crosslinking method. During cable production, the following steps are required:

[0007] (1) Obtain a conductor; (2) Extrude molten insulating material around the conductor; (3) Irradiate the conductor with extruded insulating material to crosslink it and obtain the finished product; (4) Inspect the finished product and package it onto a tray.

[0008] When performing irradiation crosslinking, it is generally necessary to outsource the irradiation operation to a manufacturer with irradiation equipment. This process incurs a lot of costs. At the same time, since the manufacturers with irradiation equipment need to schedule their operations, the stability of the production cycle cannot be guaranteed. This means that the cable manufacturer cannot control the cable production schedule, which adds many uncertainties.

[0009] 2. The insulation material is prepared by steam crosslinking. During cable production, the following steps are required:

[0010] (1) Obtain the conductor; (2) Extrude molten insulating material around the conductor; (3) Crosslink the conductor with extruded insulating material by steam to obtain the finished product; (4) Inspect the finished product and package it onto a tray.

[0011] When performing steam crosslinking, a steam environment needs to be prepared in advance so that the cable can be steam crosslinked in a timely manner after the insulation is extruded. Although the production cycle of steam crosslinking is more stable than that of radiation crosslinking, the time required for steam crosslinking is also longer, which leads to a longer production cycle and consumes a lot of energy, thereby increasing production costs. Summary of the Invention

[0012] To address the problems existing in the prior art, the present disclosure aims to provide a natural cross-linking cable manufacturing process. This disclosure enables the preparation of cables through natural cross-linking, providing significant guidance for the actual cable production process and promoting efficient and energy-saving cable production.

[0013] The natural cross-linked cable manufacturing process disclosed herein includes the following steps:

[0014] Step 1: Obtain a conductor;

[0015] Step 2: Take the naturally cross-linked raw material, extrude it, and coat it around the outer periphery of the conductor to obtain the cross-linked product;

[0016] Step 3: Take the obtained cross-linking product and let it stand for natural cross-linking. After natural cross-linking is completed, a semi-finished cable is obtained.

[0017] Step 4: Inspect the semi-finished cable obtained in Step 3. The qualified product is the finished naturally cross-linked cable.

[0018] Preferably, in step three, the temperature at which the obtained crosslinking product undergoes natural crosslinking is 25–27°C.

[0019] Preferably, in step two, the natural crosslinking material comprises the following components by weight percentage: 20% EVA, 4% metallocene PE, 6% POE, 4.5% compatibilizer, 50% aluminum hydroxide, 10% magnesium hydroxide, 0.2% copper inhibitor, 0.3% antioxidant, 2% silane, 2% organosilicon flame retardant, and 1% lubricant.

[0020] Preferably, in step two, a single-screw extruder with a compression ratio of 1.24 is used for the extrusion operation, and the extrusion process includes a feeding section, a melting section and an extrusion section in sequence along the flow direction of the naturally cross-linked raw material;

[0021] The in-mold temperature of the feeding section is 115-125℃; the in-mold temperature of the melting section is 125-135℃; and the in-mold temperature of the extrusion section is 135-140℃.

[0022] Preferably, the feeding section includes a first feeding section and a second feeding section in sequence, wherein the in-mold temperature of the first feeding section is 115-120°C and the in-mold temperature of the second feeding section is 120-125°C.

[0023] Preferably, the melting section includes a first melting section and a second melting section in sequence, wherein the in-mold temperature of the first melting section is 125-130°C and the in-mold temperature of the second melting section is 130-135°C.

[0024] Preferably, the extrusion section includes a first extrusion section, a second extrusion section, and a third extrusion section in sequence, wherein the in-mold temperature of the first extrusion section is 135-137°C; the in-mold temperature of the second extrusion section is 137-140°C; and the in-mold temperature of the third extrusion section is 137-140°C.

[0025] Preferably, the residence time of the naturally cross-linked raw material in the screw is less than or equal to 10 minutes.

[0026] Preferably, in step two, the die core and die sleeve parameters of the single-screw extruder satisfy the following:

[0027] α=(π*D0 2 / 4-π*D1 2 / 4) / (π*(2*D3+D4) 2 / 4-π*D4 2 / 4);

[0028] Where D0 represents the diameter of the die sleeve, D1 represents the diameter of the die core, D3 represents the insulation thickness of the cable to be manufactured, D4 represents the conductor diameter of the cable to be manufactured, and α represents the draw ratio of the cable to be manufactured, satisfying 2.4≤α≤2.8;

[0029] The core diameter D1 and the conductor diameter D4 satisfy the following:

[0030] 1.0mm≤D1-D4≤1.5mm.

[0031] The cable disclosed herein is prepared using the natural cross-linked cable preparation process described above.

[0032] The advantages of the natural cross-linked cable manufacturing process disclosed herein are as follows:

[0033] 1. This disclosure uses a natural cross-linking process, in which natural cross-linking raw materials are extruded onto the outer periphery of a conductor to obtain a cross-linking product. The cross-linking product is then left to stand to obtain a cable. Compared with irradiation cross-linking and steam cross-linking processes, no additional processing steps are required, which simplifies the processing steps and reduces production costs.

[0034] 2. This disclosure determines a suitable natural cross-linking temperature range through actual experiments. Under this temperature condition, the natural cross-linking raw material can undergo efficient natural cross-linking and reach a stable state in about 3 days. It can also meet the relevant parameter standards of cables. The appropriate cross-linking method can be selected according to the climate conditions, and the cross-linking environment temperature can be controlled within the suitable natural cross-linking temperature range. This has important guiding significance for the actual production process and is conducive to the efficient and energy-saving production of cables.

[0035] 3. By limiting the extrusion temperature, screw compression ratio, stretching ratio, and material residence time of the naturally cross-linked raw material, this disclosure enables the naturally cross-linked raw material to be smoothly extruded onto the outer periphery of the conductor to form an insulating layer, which is beneficial to the extrusion molding process and thus makes the finished naturally cross-linked cable conform to relevant standards. Attached Figure Description

[0036] Figure 1 This is a process flow diagram of a natural cross-linked cable preparation process for preparing flame-retardant and fire-resistant cables as described in this disclosure;

[0037] Figure 2 This is a process flow diagram of a natural cross-linked cable preparation process for preparing flame-retardant non-fire-resistant cables as described in this disclosure. Detailed Implementation

[0038] This embodiment of a natural cross-linked cable manufacturing process includes the following steps:

[0039] Step 1: Using copper rods as raw material, perform wire drawing and annealing operations to obtain a conductor;

[0040] Step 2: The natural crosslinking raw material is put into the extruder according to the formula ratio. The extruder preheats the natural crosslinking raw material and melts it in the screw. After the natural crosslinking raw material is melted and mixed to form a fluid, it passes through the barrel and the extruder head and is extruded onto the outer periphery of the conductor to obtain the crosslinking product.

[0041] Step 3: Take the obtained cross-linking product and let it stand for natural cross-linking. After natural cross-linking is completed, a semi-finished cable is obtained.

[0042] Step 4: Inspect the semi-finished cable obtained in Step 3. The inspection includes routine appearance inspection, dimensional inspection, electrical inspection, etc. The qualified product is the finished natural cross-linked cable.

[0043] Furthermore, after the fluid is extruded and coated around the conductor, the fluid can spontaneously cross-link under natural conditions. The temperature of the cross-linking environment has a significant impact on the speed of natural cross-linking and the performance of the final product, the naturally cross-linked cable. Therefore, it is necessary to investigate the changes in the cross-linking parameters and related properties of the product to be cross-linked under different ambient temperature conditions.

[0044] To achieve the above objectives, the following three experimental examples were designed. The samples in the three experimental examples were prepared according to the natural cross-linking cable preparation process described in this disclosure. They were left to stand naturally for 15 days under different ambient temperatures. The elongation, tensile strength, elongation rate, and permanent deformation of the samples were tested for the first seven days. From the 9th to the 15th day, the elongation and tensile strength were tested, and the elongation and tensile strength after aging were also tested. The elongation rate and tensile strength change rate were calculated by comparing the elongation rate and the elongation rate after aging, and the tensile strength and tensile strength after aging, thereby determining the appropriate natural cross-linking temperature range.

[0045] Experimental Example 1

[0046] The cross-linked product to be cross-linked was obtained by sequentially going through steps one and two of the natural cross-linked cable preparation process described in this disclosure. Sample 1 was placed in an environment with a temperature of 19-21°C for 15 days, and relevant physical performance tests were performed on sample 1 at 8:00 am every day to obtain the corresponding parameter indexes. The test results are shown in Table 1 and Table 2.

[0047] Experiment Example 2

[0048] The cross-linking product to be cross-linked is obtained as sample 2 by sequentially going through steps one and two of the natural cross-linking cable preparation process described in this disclosure. The natural cross-linking raw material of sample 2 must be exactly the same as that of sample 1. Sample 2 is placed in an environment with a temperature of 25-27°C for 15 days. The relevant physical properties of sample 2 are tested at 8:00 am every day to obtain the corresponding parameter index. The test results are shown in Tables 3 and 4.

[0049] Experimental Example 3

[0050] The cross-linking product to be cross-linked is obtained as sample 3 by sequentially going through steps one and two of the natural cross-linking cable preparation process described in this disclosure. The natural cross-linking raw material of sample 3 must be exactly the same as that of sample 1. Sample 3 is placed in an environment with a temperature of 31 to 33°C for 15 days. The relevant physical properties of sample 3 are tested at 8:00 am every day to obtain the corresponding parameter index. The test results are shown in Tables 5 and 6.

[0051] Table 1. Performance test data for the first seven days of Experiment Example 1

[0052]

[0053] Table 2. Performance test data from day 9 to day 15 of Experiment Example 1

[0054]

[0055] Table 3. Performance test data for the first seven days of Experiment Example 2

[0056]

[0057] Table 4. Performance test data from day 9 to day 15 of Experiment Example 2

[0058]

[0059] Table 5. Performance test data for the first 7 days of Experiment Example 3

[0060]

[0061] Table 6. Performance test data from day 9 to day 15 of Experiment Example 3

[0062]

[0063] According to Tables 1 and 2, when the ambient temperature for natural cross-linking is 19–21℃, the tensile strength of Sample 1 on day 1 is 9.2 N / mm². 2 Although it met the standards, the tensile strength was low. It only began to stabilize from the 7th day, with an average tensile strength of 13.6 N / mm². 2 The tensile strength after aging is higher than that before aging, and the rate of change in tensile strength is within the acceptable range. The average tensile strength after aging is 16.9 N / mm². 2 ;

[0064] Regarding permanent deformation, the permanent deformation of sample 1 was unacceptable on day 1, but from day 3 onwards it was within acceptable range, and began to stabilize on day 5.

[0065] Since cross-linking can improve the tensile strength of cable insulation, based on the test data and the above analysis, when the ambient temperature for natural cross-linking is 19-21℃, the cross-linking reaction of sample 1 requires about 7 days to be completed; when the ambient temperature is 19-21℃, the ambient humidity is 47%-50%.

[0066] According to Tables 3 and 4, when the ambient temperature for natural cross-linking is 25–27°C, the tensile strength of Sample 2 on day 1 is 12.5 N / mm². 2 The tensile strength was higher than the standard value. Starting from the third day, the tensile strength tended to stabilize, with an average value of 13.7 N / mm². 2 The tensile strength after aging is higher than that before aging, and the rate of change in tensile strength is within the acceptable range. The average tensile strength after aging is 16.9 N / mm². 2 ;

[0067] Regarding permanent deformation, the permanent deformation of sample 2 remained within the acceptable range, fluctuated on the 4th day, and tended to stabilize on the 5th day.

[0068] According to the experimental data, when the ambient temperature for natural cross-linking is 25-27℃, the cross-linking reaction of sample 2 takes about 3 days to complete; when the ambient temperature is 25-27℃, the ambient humidity is 58%-61%.

[0069] According to Tables 5 and 6, when the ambient temperature for natural cross-linking is 31–33℃, the tensile strength of sample 3 on day 1 is 13.7 N / mm. 2 The tensile strength was higher than the standard value. Starting from the 5th day, the tensile strength tended to stabilize, with an average tensile strength of 13.8 N / mm. 2 The tensile strength after aging is higher than that before aging, and the rate of change in tensile strength is within the acceptable range. The average tensile strength after aging is 16.7 N / mm². 2 ;

[0070] Regarding permanent deformation, the permanent deformation of sample 3 remained within acceptable limits, with a maximum permanent deformation of 10%, and it stabilized starting on the second day.

[0071] According to the experimental data, when the ambient temperature for natural cross-linking is 31-33℃, the cross-linking reaction of sample 3 takes about 5 days to complete; when the ambient temperature is 31-33℃ and the ambient humidity is 50%-53%.

[0072] According to Tables 1 to 6, the elongation of samples 1, 2 and 3 has always remained above the standard value and the difference in elongation values ​​among the three examples is not significant. The average elongation of sample 1 is better, followed by sample 2, and sample 3 is worse. However, since the elongation of all three examples is above the standard value, and the crosslinking time of sample 2 is shorter than that of the other two examples, i.e., the generation cycle is shorter, considering other performance test data, the overall performance of sample 2 is more balanced.

[0073] The data above shows that the natural cross-linking reaction is not necessarily faster at higher temperatures. At 25-27°C, the natural cross-linking speed is faster than that of the other two temperature ranges. At the same time, the overall performance of the insulation layer is more balanced compared to the other two ambient temperature test examples. Therefore, when cables made using the natural cross-linking cable preparation process described in this disclosure are naturally cross-linked at 25-27°C, a finished naturally cross-linked cable with satisfactory and relatively balanced performance can be formed in the shortest production cycle.

[0074] This disclosure uses a natural cross-linking process, in which natural cross-linking raw materials are extruded onto the outer periphery of a conductor to obtain a cross-linking product. The cross-linking product is then left to stand to obtain a cable. Compared with irradiation cross-linking and steam cross-linking processes, no additional processing steps are required, which simplifies the processing steps and reduces production costs.

[0075] This disclosure determines through actual experiments that the suitable natural crosslinking temperature range is 25-27℃. Under this temperature condition, the natural crosslinking raw material can undergo efficient natural crosslinking and reach a stable state in about 3 days, while meeting the relevant parameter standards of the cable. The appropriate crosslinking method can be selected according to the climate conditions. For example, when the climate temperature is close to this temperature range, the natural crosslinking process can be used to quickly complete the crosslinking process. At this time, there is no need to use the irradiation crosslinking process and the steam crosslinking process, and no additional processing steps are required, which can reduce processing energy consumption.

[0076] On the other hand, the temperature of the crosslinking environment can be controlled within a suitable natural crosslinking temperature range by means of a constant temperature room, so as to ensure the efficient and stable operation of the natural crosslinking process.

[0077] This disclosure determines the appropriate temperature range for natural cross-linking environment through multiple sets of experiments, enabling manufacturers to select the appropriate cross-linking method according to climatic conditions, or to ensure that the natural cross-linking reaction proceeds rapidly and efficiently by controlling the cross-linking environment temperature. This has important guiding significance for the actual production process and is conducive to the efficient and energy-saving production of cables.

[0078] Furthermore, the naturally cross-linked raw materials in step two are distributed as follows by weight percentage:

[0079] EVA (ethylene-vinyl acetate copolymer) 20%, metallocene PE (metallocene polyethylene) 4%, POE (polyolefin elastomer) 6%, compatibilizer 4.5%, aluminum hydroxide 50%, magnesium hydroxide 10%, copper inhibitor 0.2%, antioxidant 0.3%, silane 2%, organosilicon flame retardant 2%, lubricant 1%;

[0080] Among them, conventional compatibilizers such as EEA (ethylene-ethyl acrylate copolymer) and EMMA (butadiene-methyl methacrylate copolymer) can be selected;

[0081] Antioxidants such as pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and dilaurate thiodipropionate can be selected.

[0082] Polyborosiloxane can be selected as the organosilicon flame retardant;

[0083] Copper deactivators can be conventional metal deactivators such as N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine;

[0084] Lubricants such as stearic acid and magnesium stearate can be used.

[0085] The above-mentioned natural cross-linking raw material formula can quickly complete cross-linking to form an insulating sheath under an ambient temperature of 25-27℃, thereby producing finished cables that meet the standards.

[0086] Furthermore, in step two, the extrusion operation requires selecting a suitable extruder according to the natural crosslinking formula and setting the in-mold temperature of the extruder. Then, the natural crosslinking raw material is put into the extruder according to the ratio of the natural crosslinking formula. A series of processes such as mixing and melting are carried out in the extruder, and finally the natural crosslinking material is extruded onto the outer periphery of the conductor.

[0087] The selection of the screw extruder mainly depends on the compression ratio. The compression ratio needs to be selected according to the different cross-linking raw materials. If the selected compression ratio is too small, it will be difficult for the screw to transport the naturally cross-linked raw materials. In order to speed up the transport speed, it is necessary to increase the current. When the current is overloaded, it is easy to cause the main unit to trip, thus affecting the production efficiency. If the selected compression ratio is too large, the naturally cross-linked raw materials will undergo pre-cross-linking during melting. This will cause a small part of the uniform melt to become cross-linked and hardened. When extruding and wrapping the wire core, the entire layer of naturally cross-linked material will be uneven, which does not meet the relevant regulations. Therefore, in the natural cross-linked cable preparation process described in this disclosure, the compression ratio of the screw in the single-screw extruder is set to 1.2 to 1.3, preferably 1.24, through actual experiments, to ensure a smooth extrusion process and a flat and uniform extruded raw material.

[0088] During the extrusion process, the raw material channel inside the extruder includes a feeding section, a melting section, and an extrusion section in sequence along the flow direction of the naturally cross-linked raw material. The in-mold temperature of each section is set according to the melting temperature of the naturally cross-linked raw material.

[0089] The feeding section needs to preheat and transport the naturally cross-linked raw material. Therefore, the mold temperature in the feeding section needs to be slightly lower than the melting temperature of the naturally cross-linked raw material. If the mold temperature is too low, the naturally cross-linked raw material will not be able to melt completely in subsequent steps, resulting in an uneven surface and a grainy texture when extruding and wrapping the conductor, which will lead to the product performance not meeting the requirements. If the mold temperature is too high, the naturally cross-linked raw material will start to cross-link at the melting section, which will also cause the already cross-linked part to harden and coat the outer periphery of the conductor during extrusion, which is inconsistent with the state of other normally coated naturally cross-linked material, resulting in the product performance not meeting the requirements. Therefore, the mold temperature in the feeding section is set to 115-125℃.

[0090] The in-mold temperature of the melting section is matched with the melting temperature of the naturally cross-linked raw material so that the naturally cross-linked raw material reaches a completely melted state, which prepares it for subsequent extrusion coating of conductor. Therefore, the in-mold temperature of the melting section is 125-135℃.

[0091] The extrusion section involves extruding fully molten, naturally cross-linked raw materials to coat the outer periphery of the conductor. To ensure the surface properties and smoothness of the finished product, the in-mold temperature of the extrusion section needs to be set 5°C higher than that of the molten section. Therefore, the temperature of the extrusion section is set to 135–140°C.

[0092] Furthermore, the feeding section includes a first feeding section and a second feeding section. The mold temperature of the first feeding section is 115-120℃, and the mold temperature of the second feeding section is 120-125℃.

[0093] Furthermore, the melting section includes a first melting section and a second melting section, wherein the in-mold temperature of the first melting section is 125-130°C; and the in-mold temperature of the second melting section is 130-135°C.

[0094] Furthermore, the extrusion section includes a first extrusion section, a second extrusion section, and a third extrusion section. The in-mold temperature of the first extrusion section is 135–137°C; the in-mold temperature of the second extrusion section is 137–140°C; and the in-mold temperature of the third extrusion section is 137–140°C.

[0095] Furthermore, in step two, in some scenarios, it is necessary to change the color of the naturally cross-linked material extruded around the outer periphery of the core. In this case, the extruder needs to be shut down, but the naturally cross-linked material remains inside the extruder. Because the various sections of the extruder maintain a high temperature, the naturally cross-linked material will undergo pre-cross-linking and hardening in about 10 minutes, which may lead to the naturally cross-linked material blocking the die or causing unevenness on the outer periphery of the core during re-extrusion and wrapping, affecting the quality of the cable. Therefore, it is important to note that the time for shutting down the extruder should not exceed 10 minutes, or if the extruder is shut down for more than 10 minutes, it needs to be restarted to discharge the naturally cross-linked material inside the extruder before refilling.

[0096] Furthermore, the natural cross-linked cable manufacturing process described in this disclosure can be used to manufacture flame-retardant and fire-resistant cables as well as flame-retardant and non-fire-resistant cables.

[0097] The process flow diagram for preparing flame-retardant and fire-resistant cables is as follows: Figure 1 As shown;

[0098] The preparation of flame-retardant but non-fire-resistant cables does not require a fire-resistant layer wrapping process. After extruding the natural cross-linked material as the insulation layer, the finished product can be obtained through natural cross-linking.

[0099] The process flow diagram for preparing flame-retardant non-fire-resistant cables is as follows: Figure 2 As shown,

[0100] To prepare flame-retardant and fire-resistant cables, an additional fire-resistant layer wrapping process is required between step one and step two. The fire-resistant layer is generally made of mica tape, which is wrapped around the conductor obtained in step one as the fire-resistant layer.

[0101] In addition, for flame-retardant and fire-resistant cables, it is also necessary to ensure the cable's heat shrinkage performance. The draw ratio affects the cable's heat shrinkage performance; a low draw ratio results in substandard heat shrinkage performance. Therefore, the heat shrinkage performance of the cable can be ensured by controlling the cable's draw ratio. The draw ratio is the ratio of the cross-sectional area of ​​the gap formed by the die core and die sleeve to the cross-sectional area of ​​the cable insulation layer, expressed by the following formula:

[0102] α=(π*D0 2 / 4-π*D1^2 / 4) / (π*(2*D3+D4) 2 / 4-π*D4 2 / 4)

[0103] Where α is the draw ratio, D0 is the die diameter, D1 is the die core diameter, D3 is the cable insulation thickness (the thickness of the material outside the conductor), and D4 is the conductor diameter.

[0104] α must satisfy: 2.4≤α≤2.8; D3 can be determined according to relevant national regulations;

[0105] The core diameter D1 and the conductor diameter D4 satisfy the following condition: 1.0mm ≤ D1 - D4 ≤ 1.5mm;

[0106] Based on the above parameters, select appropriate die sleeves and cores for extrusion to ensure that the cable's elongation ratio meets the requirements.

[0107] This disclosure reduces the number of steps in cable manufacturing, shortens the production cycle, and lowers production costs by changing the cross-linking method of the insulation layer.

[0108] Furthermore, by exploring the conditions under which ambient temperature affects the cross-linking reaction of naturally cross-linked materials, a more suitable temperature range was determined, thereby improving production efficiency and shortening the production cycle, which has guiding significance for cable manufacturing.

[0109] Furthermore, by setting the temperature of each stage during the extrusion process, the naturally cross-linked raw materials are kept in a state of uniform mixing and plasticization from feeding to extrusion, thereby ensuring the smoothness of the insulation layer extruded and wrapped around the outer periphery of the core.

[0110] Furthermore, by setting the compression ratio of the screw in the extruder, the speed and efficiency of the screw conveying the naturally cross-linked material are ensured, and sufficient pressure is ensured to ensure the melting and plasticization of the naturally cross-linked material;

[0111] Furthermore, the draw ratio of the flame-retardant and fire-resistant cable is determined to ensure its thermal shrinkage performance.

[0112] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this disclosure.

[0113] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims disclosed herein.

Claims

1. A process for manufacturing naturally cross-linked cables, characterized in that, Includes the following steps: Step 1: Obtain a conductor; Step 2: Extrude the naturally crosslinked raw material and coat it around the conductor to obtain the crosslinked product. The naturally crosslinked raw material includes the following components by weight percentage: EVA 20%, metallocene PE 4%, POE 6%, compatibilizer 4.5%, aluminum hydroxide 50%, magnesium hydroxide 10%, copper inhibitor 0.2%, antioxidant 0.3%, silane 2%, organosilicon flame retardant 2%, lubricant 1%. Step 3: Take the obtained cross-linking product and let it stand for natural cross-linking. After natural cross-linking is completed, a semi-finished cable is obtained. Step 4: Inspect the semi-finished cable obtained in Step 3. The qualified product is the finished naturally cross-linked cable.

2. The natural cross-linked cable manufacturing process according to claim 1, characterized in that, In step three: The temperature for natural cross-linking of the obtained cross-linked product is 25–27°C.

3. The natural cross-linked cable manufacturing process according to claim 1, characterized in that, In step two, a single-screw extruder with a compression ratio of 1.24 is used for extrusion. The extrusion process includes a feeding section, a melting section and an extrusion section in sequence along the flow direction of the naturally cross-linked raw material. The in-mold temperature of the feeding section is 115-125℃; the in-mold temperature of the melting section is 125-135℃; and the in-mold temperature of the extrusion section is 135-140℃.

4. The natural cross-linked cable manufacturing process according to claim 3, characterized in that, The feeding section includes a first feeding section and a second feeding section in sequence. The in-mold temperature of the first feeding section is 115-120℃, and the in-mold temperature of the second feeding section is 120-125℃.

5. The natural cross-linked cable manufacturing process according to claim 3, characterized in that, The melting section includes a first melting section and a second melting section in sequence. The in-mold temperature of the first melting section is 125-130°C, and the in-mold temperature of the second melting section is 130-135°C.

6. The natural cross-linked cable manufacturing process according to claim 3, characterized in that, The extrusion section includes a first extrusion section, a second extrusion section, and a third extrusion section in sequence. The in-mold temperature of the first extrusion section is 135-137°C; the in-mold temperature of the second extrusion section is 137-140°C; and the in-mold temperature of the third extrusion section is 137-140°C.

7. The natural cross-linked cable manufacturing process according to claim 3, characterized in that, The residence time of the naturally cross-linked raw material in the screw is less than or equal to 10 minutes.

8. The natural cross-linked cable manufacturing process according to claim 3, characterized in that, In step two, the die core and die sleeve parameters of the single-screw extruder satisfy the following: α=(π*D0) 2 / 4-π*D1 2 / 4) / (π*(2*D3+D4) 2 / 4-π*D4 2 / 4); Where D0 represents the diameter of the die sleeve, D1 represents the diameter of the die core, D3 represents the insulation thickness of the cable to be manufactured, D4 represents the conductor diameter of the cable to be manufactured, and α represents the draw ratio of the cable to be manufactured, satisfying 2.4≤α≤2.8; The core diameter D1 and the conductor diameter D4 satisfy the following: 1.0mm≤D1-D4≤1.5mm.

9. A cable, characterized in that, It is prepared using the natural cross-linked cable preparation process described in any one of claims 1 to 8.

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