Polyvinyl chloride cable insulation layer heating and curing control method

Abstract

This invention provides a method for controlling the heating and curing of polyvinyl chloride (PVC) cable insulation, comprising multiple stages. In the substrate preparation stage, a cable to be treated is provided. In the preheating and penetration stage, the cable to be treated is controlled to enter the preheating temperature zone to expel air bubbles from the mixed layer. In the segmented heating stage, temperature parameters for each temperature zone in the heating segment are set according to the production line speed and the thickness of the insulation layer; the multiple temperature zones along the cable travel direction are controlled to exhibit an increasing temperature gradient. In the curing and heat preservation stage, a heat preservation time is set within the curing temperature zone to maintain temperature stability and complete the cross-linking reaction of the insulation material. In the controlled cooling stage, the cured cable is sent into the cooling zone, and a segmented cooling rate is set. In the dynamic adjustment stage, the production line speed signal is collected in real time, and the set temperature and dwell time of each stage temperature zone are dynamically adjusted according to changes in the line speed signal.

Description

Technical Field

[0001] This invention relates to the field of cable insulation manufacturing technology, and in particular to a method for controlling the heating and curing of polyvinyl chloride (PVC) cable insulation. Background Technology

[0002] In the production process of PVC cable insulation, heat curing is typically used to induce a cross-linking reaction in the insulation layer coated on the cable surface. Currently, a common practice in the industry is to feed the insulated cable into a heated tunnel, set a fixed heating temperature, and complete curing once the cable passes through that temperature zone. For example, patent application number 2013106971620 discloses such a method for manufacturing cable core insulation.

[0003] However, in actual production, it was found that there are several shortcomings in using a single constant-temperature heating method.

[0004] First, air bubbles are prone to remain inside the insulation layer. This is because a small amount of air is inevitably trapped during the coating process, and the surface solidifies first during constant-temperature heating, trapping the air bubbles inside and affecting the insulation's density and withstand voltage. Second, for thicker insulation layers, due to the slow thermal conductivity of PVC, the outer layer may be fully cured while the inner layer has not yet reached the cross-linking temperature, resulting in inconsistent curing levels between the inner and outer layers and reducing the overall strength of the insulation layer. Third, the cooling process after curing often uses natural cooling or single air cooling. If the cooling rate is too rapid, significant shrinkage stress will be generated inside the insulation layer, potentially leading to cracks or dimensional deformation during subsequent storage or use. Furthermore, the production line speed is not always constant. When the line speed changes, the residence time of the cable in each temperature zone also changes, and a fixed temperature cannot compensate for this time difference, resulting in significant fluctuations in the curing quality of cables produced at different speeds. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems by providing a method for controlling the heating and curing of polyvinyl chloride cable insulation.

[0006] The technical solution of this invention is a method for controlling the heating and curing of polyvinyl chloride cable insulation, comprising: Substrate preparation stage: Provide a cable to be treated with a mixed layer of polyvinyl chloride adhesive and calcium carbonate particles already coated on the surface, the mixed layer serving as the cable's insulation layer; Preheating and penetration stage: Control the cable to be treated to enter the preheating temperature zone, and set the preheating temperature to be lower than the curing start temperature of the adhesive; within the preheating temperature zone, the heat-softened adhesive in the insulation layer is encouraged to penetrate into the gaps between calcium carbonate particles and expel air bubbles inside the mixed layer, so as to enhance the bonding foundation inside the insulation layer. Segmented heating stage: Based on the production line speed and the thickness of the insulation layer, the temperature parameters of each temperature zone in the heating stage are set; the multiple temperature zones along the cable travel direction are controlled to present an increasing temperature gradient. By implementing multi-segment heating on the insulation layer, the inner layer material and the outer layer material reach the required curing temperature simultaneously, so as to reduce the radial thermal conduction temperature difference between the inner and outer sides of the insulation layer. Curing and heat preservation stage: Set the heat preservation time within the curing temperature zone to maintain temperature stability and complete the cross-linking reaction of the insulating material; at the same time, monitor the heat distribution to prevent local overheating from causing material degradation and ensure uniform insulation performance. Controlled cooling stage: The cured cable is sent into the cooling zone and a segmented cooling rate is set; by controlling the temperature drop slope during the cooling process, the internal stress generated inside the insulation layer is reduced, and the insulation layer is prevented from cracking or deforming. Dynamic adjustment stage: Real-time acquisition of production line speed signals, and dynamic adjustment of the set temperature of each stage temperature zone based on changes in the line speed signal. By compensating for changes in dwell time caused by changes in line speed, the total amount of heat received by the cable insulation layer remains consistent under different production speeds.

[0007] In one implementation, during the preheating and penetration stage, the preheating temperature is set within the range of: higher than the viscous flow temperature of the adhesive and lower than the curing initiation temperature of the adhesive.

[0008] In one implementation, during the preheating and penetration stage, the effective heating length or preheating temperature value of the preheating zone is set according to the viscosity of the adhesive and the average particle size of the calcium carbonate particles, so as to completely fill the gaps between the calcium carbonate particles using the adhesive with decreased viscosity.

[0009] As one implementation method, in the segmented heating stage, the temperature parameters are set by increasing the number of temperature zones in the heating section or extending the travel distance of the cable in the heating section as the insulation layer thickness increases.

[0010] As one implementation, the segmented heating stage also includes adjusting the heating intensity according to the calcium carbonate ratio in the insulation layer. When the calcium carbonate content increases, the heating power of the heating stage is increased.

[0011] As one implementation method, during the curing and heat preservation stage, an airflow isolation device is used between each temperature zone to prevent hot air crosstalk between different temperature zones.

[0012] In one implementation, the cooling rate in the controlled cooling stage is divided into at least two stages, wherein the initial cooling rate near the curing temperature zone is lower than the subsequent cooling rate.

[0013] As one implementation method, during the dynamic adjustment phase, when the production line speed increases, the set temperature of each temperature zone is simultaneously increased to compensate for the heat loss caused by the shortened residence time of the cable in the temperature zone.

[0014] As one implementation method, during the dynamic adjustment phase, a correspondence table between line speed and temperature is established to achieve real-time correction of temperature parameters when the production line fluctuates.

[0015] In one implementation, each temperature zone is set in a closed thermal circulation tunnel, and the heat exchange efficiency of each stage is controlled by adjusting the speed of the circulating fan.

[0016] The beneficial effects of this invention compared to existing technologies are that the polyvinyl chloride (PVC) cable insulation layer heating and curing control method utilizes preheating penetration, segmented heating, controlled cooling, and dynamic adjustment—these are not independent process segments. Preheating penetration first removes air bubbles and fills the gaps between particles; segmented heating ensures that the inner and outer layers reach the cross-linking temperature almost simultaneously; controlled cooling suppresses internal stress caused by shrinkage differences; and dynamic adjustment ensures that the above three stages can be reproduced at different linear speeds. These four processes work together to form the insulation layer in a state free of air bubbles, without differences in curing between the inner and outer layers, and without cooling cracks. This inter-stage connection and compensation relationship leads to an overall improvement in the curing quality of the PVC cable insulation layer. Attached Figure Description

[0017] Figure 1 A flowchart of a method for controlling the heating and curing of polyvinyl chloride cable insulation layer provided in an embodiment of the present invention. Detailed Implementation

[0018] The above and other embodiments and advantages of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] In one implementation, such as Figure 1As shown. The method for controlling the heating and curing of PVC cable insulation includes: a substrate preparation stage: providing a cable to be treated with a mixed layer of PVC adhesive and calcium carbonate particles already coated on its surface, the mixed layer serving as the cable's insulation layer; a preheating penetration stage: controlling the cable to be treated to enter a preheating temperature zone, setting the preheating temperature below the curing initiation temperature of the adhesive; within the preheating temperature zone, promoting the softened adhesive in the insulation layer to penetrate into the gaps between the calcium carbonate particles and expelling air bubbles inside the mixed layer, thereby enhancing the bonding foundation within the insulation layer; a segmented heating stage: setting the temperature parameters of each temperature zone in the heating stage according to the production line speed and the thickness of the insulation layer; controlling multiple temperature zones along the cable's travel direction to exhibit an increasing temperature gradient, and through multi-segment heating of the insulation layer, ensuring that the inner and outer layer materials reach curing simultaneously. The process involves several stages: First, the required temperature is set to minimize the radial thermal conductivity difference between the inner and outer surfaces of the insulation layer. Second, during the curing and insulation stage, a set insulation time is established within the curing temperature zone to maintain temperature stability and complete the cross-linking reaction of the insulation material. Simultaneously, heat distribution is monitored to prevent localized overheating that could lead to material degradation, ensuring uniform insulation performance. Third, in the controlled cooling stage, the cured cable is placed in a cooling zone with a segmented cooling rate. By controlling the temperature drop slope during cooling, internal stress generated within the insulation layer is reduced, preventing cracks or dimensional deformation. Fourth, in the dynamic adjustment stage, the production line speed signal is collected in real time, and the set temperature and dwell time of each stage are dynamically adjusted based on changes in the line speed signal. By compensating for heating time differences caused by changes in line speed, the total amount of heat received by the cable insulation layer remains consistent across different production speeds.

[0020] In this embodiment, the polyvinyl chloride (PVC) cable insulation layer heating and curing control method, compared to the existing technology which only sets a single constant temperature heating method of 100-120°C, subdivides the curing process into multiple collaboratively operating stages. First, in the substrate preparation stage, the production line provides a cable to be treated with a surface already coated with a mixture of PVC adhesive and calcium carbonate particles; this mixture serves as the insulation layer after cable molding. Next, in the preheating and penetration stage, the system controls the cable to enter the preheating temperature zone. The key here is setting a specific temperature threshold, i.e., below the adhesive's curing initiation temperature. Within this temperature zone, the adhesive softens upon heating but has not yet begun a vigorous cross-linking and curing reaction. This gives the liquid adhesive sufficient time to penetrate and fill the gaps between the calcium carbonate particles. Simultaneously, the thermal expansion effect expels air bubbles trapped during coating, thereby strengthening the bonding foundation within the insulation layer at the microscopic level and preventing voids after curing. Next is the segmented heating stage. Instead of single-point forced heating, the system sets an increasing temperature gradient for multiple consecutive temperature zones within the heating segment based on the current production line speed and the designed thickness of the insulation layer. This multi-stage heating method allows heat to be conducted from the outer surface of the insulation layer to the inner layer close to the cable core at a gradual and continuous pace. This ensures that the inner and outer layers reach the temperature required for the cross-linking reaction as synchronously as possible, effectively reducing the radial temperature difference in the insulation layer and solving the problem of uneven heating between the inner and outer layers in existing technologies. Following this, the curing and insulation stage begins. Within the core curing temperature zone, a set insulation time and a stable temperature field are maintained to ensure that the polyvinyl chloride (PVC) fully completes the cross-linking reaction. During this stage, the control system continuously monitors the spatial heat distribution to prevent thermal degradation caused by localized heat accumulation, ensuring the uniformity of the electrical performance of the entire cable insulation layer. After curing, a controlled cooling stage begins. The cable is placed in the cooling zone with segmented cooling rate control. By deliberately flattening the temperature drop slope in the initial cooling phase, sufficient shrinkage buffer time is given to the high-temperature polymer material, effectively reducing the huge shrinkage stress generated inside the insulation layer due to sudden cooling. This fundamentally prevents cracking and dimensional deformation of the insulation layer during subsequent winding or service environments. Finally, the dynamic adjustment stage runs throughout the entire process. The central control system collects the linear speed signal of the traction machine in real time. When the linear speed fluctuates, it dynamically adjusts the temperature setpoints of each temperature zone and the expected residence time of the cable within that zone. Its core control principle lies in compensating for the increase or decrease in heating time caused by varying linear speeds through temperature fluctuations, ensuring that regardless of production speed changes, the total amount of heat received by the cable insulation layer per unit length always remains at the preset curing energy baseline.

[0021] Therefore, in this embodiment, preheating penetration, staged heating, controlled cooling, and dynamic adjustment are not independent process segments. Preheating penetration first removes air bubbles and fills the gaps between particles; staged heating ensures that the inner and outer layers reach the cross-linking temperature almost simultaneously; controlled cooling suppresses internal stress caused by shrinkage differences; and dynamic adjustment ensures that the above three stages can be reproduced at different linear speeds. These four processes work together to form the insulation layer in a state free of air bubbles, without differences in curing between the inner and outer layers, and without cooling cracks. Using any one of the steps—preheating, gradient heating, or staged cooling—in isolation cannot simultaneously eliminate these three types of defects. It is this inter-stage connection and compensation that brings about an overall improvement in curing quality that cannot be achieved by a single feature.

[0022] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method, in the preheating penetration stage, sets the preheating temperature to a range that is higher than the adhesive flow temperature and lower than the adhesive curing initiation temperature.

[0023] In this embodiment, the preheating temperature range is clearly defined during the preheating and penetration stage: this temperature must be higher than the viscous flow temperature of the adhesive and strictly lower than the curing initiation temperature of the adhesive. The viscous flow temperature refers to the critical temperature point at which the polyvinyl chloride adhesive transitions from a highly elastic state to a viscous fluid state with good flowability. For example, if a certain formulation adhesive begins to exhibit fluid properties at 80°C and initiates irreversible cross-linking and curing at 110°C, then the preheating temperature will be strictly controlled within the range of 85°C to 95°C. The advantage of this setting is that if the temperature is lower than the viscous flow temperature, the adhesive is too viscous and cannot flow effectively between particles; if the temperature reaches or exceeds the curing initiation temperature, the adhesive surface will quickly form a skin or harden completely, losing its penetration ability and causing internal air bubbles to be permanently sealed in the insulation layer.

[0024] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method, during the preheating penetration stage, sets the effective heating length or preheating temperature value of the preheating temperature zone according to the viscosity of the adhesive and the average particle size of the calcium carbonate particles, so as to completely fill the gaps between the calcium carbonate particles using the adhesive with decreased viscosity.

[0025] In this embodiment, the control logic for the preheating and penetration stage is refined. The system sets the effective heating length or specific preheating temperature value of the preheating zone based on the specific viscosity index of the adhesive used and the average particle size of the incorporated calcium carbonate particles. In this embodiment, the smaller the particle size of the calcium carbonate particles, the narrower the capillary channels between the particles, and the greater the resistance required for adhesive penetration; similarly, the higher the initial viscosity of the adhesive, the worse its flowability. For example, when the production line switches to using ultrafine calcium carbonate as filler, the control system automatically extends the effective heating length of the preheating zone, allowing the cable to run a few more meters in that zone, or appropriately increases the preheating temperature within the allowable safety range to further reduce the adhesive viscosity. This utilizes a longer softening time or better flowability to ensure that the adhesive, after viscosity reduction, can completely and seamlessly fill the gaps between the fine calcium carbonate particles, forming a dense insulation structure.

[0026] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method sets the temperature parameters in the segmented heating stage by increasing the number of temperature zones in the heating stage or extending the cable travel distance in the heating stage as the insulation layer thickness increases.

[0027] In this embodiment, the temperature parameters during the segmented heating stage are directly related to the thickness of the insulation layer: as the designed thickness of the insulation layer increases, the system automatically increases the number of temperature zones actually used in the heating stage, or extends the cable's travel distance in the heating stage through mechanical structures. In this embodiment, the insulation material is inherently a poor conductor of heat. When the insulation layer is thicker, for example, increasing from the conventional 2 mm to 5 mm, the time required for heat to conduct from the surface to the inner layer is significantly prolonged. If rapid heating with short distances and few temperature zones is maintained, the surface will inevitably overheat and carbonize. Therefore, by increasing the number of temperature zones, such as expanding the original two incremental temperature zones to four, the system lengthens and slows down the heating curve, giving sufficient time for heat to conduct inward, ensuring that the inner layer is steadily heated to a solidified state without damaging the outer layer structure.

[0028] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method further includes adjusting the heating intensity according to the calcium carbonate ratio in the insulation layer during the segmented heating stage. When the calcium carbonate content increases, the heating power of the heating stage is increased.

[0029] In this embodiment, heating intensity adjustment based on the calcium carbonate ratio in the insulation layer is introduced. When the mass percentage of calcium carbonate filler in the mixed layer increases, the system actively increases the heating power of the heating section. In this embodiment, the specific heat capacity and thermal conductivity of inorganic calcium carbonate differ significantly from those of organic polyvinyl chloride resin. An increase in calcium carbonate content means a change in the overall heat absorption capacity of the insulation layer, typically requiring more heat to achieve the same temperature rise. For example, when the calcium carbonate addition ratio is increased from 20% to 40% in the insulation layer formulation to improve flame retardancy, the actual temperature reached by the cable will be lower than expected if the heating power remains unchanged. In this case, the control system compensates for the heat loss due to the increased filler by increasing the output power of the heating element, ensuring that the temperature rise curve does not deviate.

[0030] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method employs an airflow isolation device to prevent hot air crosstalk between different temperature zones during the curing and heat preservation stage.

[0031] In this embodiment, airflow isolation devices are used between different temperature zones, particularly between the insulation zone and the preceding heating zone and the subsequent cooling zone, to prevent hot air crosstalk. Industrial heating tunnels typically involve forced hot air circulation. Without isolation, the 100°C hot air from the heating zone and the 120°C hot air from the insulation zone will mix disorderly, disrupting the designed increasing temperature gradient and making the actual temperature field uncontrollable. By installing airflow isolation devices such as air dampers or high-pressure air curtains at the boundaries of each temperature zone, the independent thermal fields within each zone can be effectively locked, allowing the crosslinking reaction to complete at a stable ambient temperature. This is a key process for ensuring the stability of continuous production batches.

[0032] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method includes a controlled cooling stage in which the cooling rate is divided into at least two stages, wherein the initial cooling rate near the curing temperature zone is lower than the subsequent cooling rate.

[0033] In this embodiment, the controlled cooling method breaks through the traditional natural air cooling or single water cooling methods, explicitly requiring the cooling rate to be divided into at least two stages, and the core principle is that the initial cooling rate near the curing temperature zone must be significantly lower than the subsequent cooling rates. In this embodiment, the insulation layer that has just left the curing temperature zone is still in a high-temperature expansion state. If it is directly exposed to room temperature strong wind or cold water at this time, i.e., an extremely high cooling rate, the surface of the insulation layer will instantly shrink and solidify, while the interior is still in a thermal expansion state. This drastic conflict between internal and external volume changes will generate fatal structural internal stress. By adopting a slow-then-rapid cooling strategy, the first stage is to cool slowly at a low rate, for example, at a slope of 10°C per minute, to near the glass transition temperature of polyvinyl chloride, allowing the inner and outer layers time to shrink synchronously and release stress; after the structure is basically stable, it then enters the subsequent high-speed cooling zone to quickly drop to room temperature, which ensures both product quality and efficient operation of the production line.

[0034] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method, during the dynamic adjustment stage, synchronously increases the set temperature of each temperature zone when the production line speed increases, in order to compensate for the heat loss caused by the shortened residence time of the cable in the temperature zone.

[0035] In this embodiment, the specific control method for increasing production line speed is as follows: when the linear speed of the traction equipment is detected to increase, the central control system will synchronously and proportionally increase the set temperature of each temperature zone. In this embodiment, the completion of the curing reaction is essentially the integral of temperature and time, i.e., the total amount of heat received. When the linear speed increases from the original 100 meters / minute to 120 meters / minute, the time for the cable to pass through any fixed-length temperature zone will be passively shortened. To compensate for the lost heat due to the shortened time, the system must increase the ambient temperature of that temperature zone, thereby increasing the driving force of heat conduction, i.e., increasing the temperature difference, and transferring the same total amount of heat energy to the insulation layer in a shorter time, so that the degree of curing of the cable still meets the standard when it leaves the production line.

[0036] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method, during the dynamic adjustment stage, establishes a correspondence table between line speed and temperature to achieve real-time correction of temperature parameters when the production line fluctuates.

[0037] In this embodiment, the system does not rely entirely on complex lag calculations. Instead, it pre-establishes and stores a mapping matrix (a table showing the correspondence between line speed and temperature) to achieve real-time, delay-free correction of temperature parameters during production line fluctuations. In this embodiment, extensive prior testing calibrates the optimal temperature combinations for different cable specifications at different line speeds and inputs this data into the PLC or DCS control system. In actual production, if the line speed data fed back by the encoder changes abruptly, the control system does not need to undergo lengthy calculations and PID oscillation adjustments. Instead, it directly looks up the corresponding target temperature value from the table and executes it. This lookup-based deterministic feedforward control completely eliminates defective sections caused by calculation delays and greatly improves the production line's resistance to speed fluctuations.

[0038] In one embodiment, the polyvinyl chloride cable insulation layer heating and curing control method involves setting each temperature zone within a closed thermal circulation tunnel, and controlling the heat exchange efficiency at each stage by adjusting the rotation speed of the circulating fan.

[0039] In this embodiment, simply increasing the air temperature is insufficient to guarantee rapid heat penetration into the cable; the airflow velocity, i.e., the convective heat transfer coefficient, also plays a crucial role. During the preheating and penetration stage or in the production of products with thicker insulation layers, the system increases the airflow and pressure of hot air scouring the cable surface by increasing the rotation speed of the circulating fan while maintaining the upper temperature limit. This forced convection rapidly strips away the cold air adhering layer from the cable surface, maximizing heat exchange efficiency and resulting in more uniform and efficient heat distribution.

[0040] The specific embodiments described above further illustrate the inventive purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, or improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the heat curing of polyvinyl chloride cable insulation layer, characterized in that, include Substrate preparation stage: Provide a cable to be treated with a mixed layer of polyvinyl chloride adhesive and calcium carbonate particles already coated on the surface, the mixed layer serving as the cable's insulation layer; Preheating and penetration stage: Control the cable to be treated to enter the preheating temperature zone, and set the preheating temperature to be lower than the curing start temperature of the adhesive; Within the preheating temperature zone, the heat-softened adhesive in the insulation layer is encouraged to penetrate into the gaps between calcium carbonate particles and expel air bubbles from the interior of the mixed layer, thereby enhancing the bonding foundation within the insulation layer. Segmented heating stage: Based on the production line speed and the thickness of the insulation layer, the temperature parameters of each temperature zone in the heating stage are set; the multiple temperature zones along the cable travel direction are controlled to present an increasing temperature gradient. By implementing multi-segment heating on the insulation layer, the inner layer material and the outer layer material reach the required curing temperature simultaneously, so as to reduce the radial thermal conduction temperature difference between the inner and outer sides of the insulation layer. Curing and heat preservation stage: Set the heat preservation time within the curing temperature zone to maintain temperature stability and complete the cross-linking reaction of the insulating material; at the same time, monitor the heat distribution to prevent local overheating from causing material degradation and ensure uniform insulation performance. Controlled cooling stage: The cured cable is sent into the cooling zone and a segmented cooling rate is set; by controlling the temperature drop slope during the cooling process, the internal stress generated inside the insulation layer is reduced, and the insulation layer is prevented from cracking or deforming. Dynamic adjustment stage: Real-time acquisition of production line speed signals, and dynamic adjustment of the set temperature of each stage temperature zone based on changes in the line speed signal. By compensating for changes in dwell time caused by changes in line speed, the total amount of heat received by the cable insulation layer remains consistent under different production speeds.

2. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 1, characterized by, During the preheating and penetration stage, the preheating temperature is set within the range of: higher than the viscous flow temperature of the adhesive and lower than the curing initiation temperature of the adhesive.

3. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 2, characterized by, During the preheating and penetration stage, the effective heating length or preheating temperature value of the preheating zone is set according to the viscosity of the adhesive and the average particle size of the calcium carbonate particles, so as to completely fill the gaps between the calcium carbonate particles with the adhesive whose viscosity has decreased.

4. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 1, characterized by, In the segmented heating stage, the temperature parameters are set by increasing the number of temperature zones in the heating section or extending the travel distance of the cable in the heating section as the insulation layer thickness increases.

5. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 4, characterized by, The segmented heating stage also includes adjusting the heating intensity according to the calcium carbonate ratio in the insulation layer. When the calcium carbonate content increases, the heating power of the heating stage is increased.

6. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 1, characterized by, During the curing and heat preservation stage, airflow isolation devices are used between different temperature zones to prevent hot air crosstalk between different temperature zones.

7. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 1, characterized by, In the controlled cooling phase, the cooling rate is divided into at least two stages, wherein the initial cooling rate near the curing temperature zone is lower than the subsequent cooling rate.

8. The method for controlling the heating and curing of polyvinyl chloride cable insulation layer according to claim 1, characterized in that, During the dynamic adjustment phase, as the production line speed increases, the set temperature of each temperature zone is simultaneously increased to compensate for the heat loss caused by the shortened residence time of the cable within the temperature zone.

9. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 1, characterized by, During the dynamic adjustment phase, a table showing the correspondence between line speed and temperature is established to enable real-time correction of temperature parameters when the production line fluctuates.

10. The polyvinyl chloride cable insulation layer heat-curing control method according to claim 1, characterized by, Each temperature zone is set in a closed thermal circulation tunnel, and the heat exchange efficiency of each stage is controlled by adjusting the speed of the circulating fan.

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