A segmented temperature and pressure vulcanization process that follows the progress of rubber crosslinking

Abstract

This invention discloses a segmented temperature and pressure vulcanization process that follows the crosslinking progress of rubber, specifically relating to the field of rubber product vulcanization processing technology. The process includes the following steps: Step S1, calibration of rubber compound crosslinking characteristics; Step S2, preset of segmented process parameters: based on the calibration results, combined with product thickness, rubber compound type, and operating conditions, preset the temperature rise curve, pressure rise curve, crosslinking degree threshold, and deviation adjustment threshold for each vulcanization stage; Step S3, online monitoring of mold closing; Step S4, segmented closed-loop temperature and pressure regulation; Step S5, vulcanization termination, cooling, and demolding. This invention sets differentiated temperature and pressure parameters for each stage based on the characteristics of the three stages of the rubber crosslinking reaction, and ensures that the vulcanization process always matches the crosslinking progress through real-time crosslinking degree monitoring and dynamic feedback adjustment, achieving precise matching between the vulcanization process and the crosslinking progress, thus avoiding over-vulcanization and under-vulcanization problems.

Description

Technical Field

[0001] This invention relates to the field of rubber product vulcanization processing technology, specifically to a segmented temperature and pressure vulcanization process that follows the progress of rubber crosslinking. Background Technology

[0002] Rubber vulcanization is the core process for the cross-linking of linear rubber macromolecules to form a three-dimensional network elastic structure, directly determining the mechanical properties, service life, and dimensional accuracy of rubber products. Currently, the mass production of rubber flat products in China generally adopts a steady-state vulcanization process with fixed temperature and cavity pressure throughout the entire process. The process parameters are determined solely based on empirical values ​​from rubber compound formulations, resulting in several inherent defects: First, in the early stages of vulcanization, the high fluidity of the rubber compound makes it highly susceptible to localized scorching under high temperature and pressure, leading to internal porosity and material shortages in the product. Second, during the peak reaction rate phase in the middle of the cross-linking reaction, the constant temperature and pressure cannot match the exothermic rate of cross-linking, resulting in excessive cross-linking of the surface layer and insufficient cross-linking of the core layer, leading to extremely poor consistency between internal and external cross-linking. Third, in the later stages of vulcanization, cross-linking tends to saturate, and the constant high temperature accelerates the thermal degradation of rubber molecules, reducing the product's aging and abrasion resistance. Fourth, fluctuations in raw material batches and workshop temperature and humidity can lead to significant differences in the degree of vulcanization within the same batch, resulting in a low product qualification rate.

[0003] Existing segmented vulcanization processes used in flat vulcanizing machines only provide broad parameter ranges for temperature and pressure, without combining real-time crosslinking progress control of the rubber compound with closed-loop control. These are timed segmented processes that cannot adapt to real-time fluctuations in the rubber compound's reaction. At the same time, existing similar processes have five major technical deficiencies: no standardized practical procedures for crosslinking characteristic calibration, no fully reproducible mass production examples, no parallel comparison data with traditional processes, no details of online monitoring closed-loop hardware and algorithms, and no differentiated process data for multiple types of rubber compounds. The technology is not sufficiently disclosed, the process has poor reproducibility, cannot meet patent authorization examination standards, and is difficult to adapt to the industrial-scale mass production of flat vulcanization. Summary of the Invention

[0004] The purpose of this invention is to provide a segmented temperature and pressure vulcanization process that follows the progress of rubber crosslinking, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a segmented temperature and pressure vulcanization process that follows the progress of rubber crosslinking, comprising the following steps: Step S1, crosslinking characteristics calibration of rubber compound: vulcanization characteristics test is carried out on the compound to be processed. Based on the crosslinking reaction rate and the crosslinking degree ratio, the vulcanization is divided into three stages: induction period, acceleration period and stabilization period. The initial temperature and pressure reference parameters for each stage are verified. Step S2, Preset segmented process parameters: Based on the calibration results, combined with the product thickness, rubber compound type and operating conditions, preset the temperature rise curve, pressure rise curve, crosslinking degree threshold and deviation adjustment threshold for each vulcanization stage; Step S3, Online monitoring of mold closing: After the compounded rubber is put into the mold of the flat vulcanizing machine and the mold is closed, the temperature of the rubber material in the mold, the cavity pressure and cross-linking characteristic parameters are collected in real time through the embedded sensing unit in the mold. The main control unit calculates the real-time degree of cross-linking based on the multi-parameter fusion prediction model. Step S4, segmented closed-loop temperature and pressure regulation: compare the real-time crosslinking degree with the preset crosslinking degree threshold. When the deviation exceeds the preset threshold, rely on the closed-loop regulation module to dynamically adjust the heating power of the vulcanizing machine and the hydraulic oil supply pressure in the order of priority: temperature first, pressure second, and pressure holding time last. Perform variable temperature and pressure vulcanization in stages so that the vulcanization process conditions can be adaptively adjusted according to the real-time crosslinking progress of the rubber compound. Step S5, Vulcanization Termination Cooling and Demolding: After the real-time crosslinking degree reaches the preset target value, heating and pressurization are stopped. After controllable cooling until the core layer temperature of the product reaches the standard, the mold is opened and the product is demolded to complete the vulcanization process.

[0006] Furthermore, in step S1, the criteria for dividing the three vulcanization stages are as follows: Induction period: Crosslinking degree 0%~10%, corresponding to the interval from the start of the vulcanization reaction to the sum of the minimum torque value and 10% of the maximum torque increment; Acceleration period: Crosslinking degree 10%~90%, corresponding to the interval from the end of the induction period to the torque reaching the sum of the minimum torque value and 90% of the maximum torque increment; Stable period: The degree of cross-linking is above 90%, which corresponds to the stage where the torque enters the plateau range after the acceleration period ends. The plateau range is defined as the torque fluctuation not exceeding 2% within 1 minute.

[0007] Furthermore, in step S1, the vulcanization characteristic test is performed using a rotorless vulcanizer or DSC differential scanning calorimetry. The rotorless vulcanizing apparatus method includes: setting a reference test temperature based on the rubber type, using a closed rotorless vulcanizing apparatus under a fixed oscillation frequency of 1.7 Hz and an oscillation amplitude of ±0.5 degrees, acquiring the vulcanizing torque-time dynamic curve, and dividing the three vulcanization stages by torque change characteristics; wherein, the reference test temperature set for the rubber type includes: 150℃ for natural rubber, 160℃ for styrene-butadiene rubber, 155℃ for nitrile rubber, and 165℃ for chloroprene rubber; The DSC differential scanning calorimetry method includes: performing non-isothermal pre-test and isothermal precision test on the compound sample under nitrogen protective atmosphere and nitrogen flow rate of 50 mL / min, characterizing the degree of crosslinking by the ratio of cumulative crosslinking heat release to total crosslinking heat release, and dividing the three vulcanization stages by 10% and 90% heat release ratio.

[0008] Further, in step S3, the real-time crosslinking degree is calculated by a multi-parameter fusion prediction model, and the calculation formula of the multi-parameter fusion prediction model is: ; In the formula, For real-time crosslinking degree, The real-time dielectric constant of the rubber compound. Temperature of the core layer of the rubber compound. For the real-time pressure of the cavity; , , , The model employs a dual-mode operation of offline calibration and online self-correction, with the calibration coefficients automatically iteratively corrected every 10 vulcanization cycles.

[0009] Further, in step S4, the hierarchical adjustment logic of the closed-loop control module includes: The real-time crosslinking degree is compared with a preset crosslinking degree curve. When the deviation exceeds a preset threshold, a deviation signal is output. The preset threshold is ±3% to ±8% of the crosslinking degree deviation. Based on the deviation signal, the vulcanization process parameters are dynamically adjusted in a standardized step size of ±1℃ for temperature, ±0.3MPa for pressure, or ±20s for holding time, according to the priority order of temperature first, pressure second, and holding time last. Set safety boundaries for parameters, locking the maximum vulcanization temperature to no more than 180℃ and the maximum vulcanization pressure to no more than 90% of the equipment's rated hydraulic pressure, to prevent thermal degradation of the rubber compound and equipment overload.

[0010] Furthermore, in steps S2 and S4, the segmented temperature and pressure control strategy for the three major stages is as follows: Induction period: Maintain a relatively low temperature and low pressure, with the temperature controlled between 80℃ and 120℃ and the pressure controlled between 2MPa and 5MPa, to ensure that the rubber compound fills the mold completely and to prevent early scorching; Acceleration phase: Temperature and pressure gradually increase as the crosslinking reaction progresses. The heating rate is controlled at 5℃ / min to 10℃ / min, and the pressure rate is controlled at 0.5MPa / min to 1.5MPa / min, in order to match the exothermic rate of crosslinking and promote the dense formation of the crosslinking network. Stabilization period: Maintain constant temperature and pressure, with temperature fluctuations controlled within ±1℃ and pressure fluctuations controlled within ±0.2MPa, so that the cross-linking reaction tends to be perfect and the thermal degradation due to oversulfurization is avoided.

[0011] Furthermore, in step S3, the mold-embedded sensing unit includes a temperature sensor, a cavity pressure sensor, and a crosslinking feature sensor; The temperature sensors are two PT100 platinum resistance thermometers, which are embedded in the working surfaces of the upper and lower cavities of the mold, respectively, to simultaneously collect the temperature of the surface and core layers of the rubber material. The sampling frequency is 1Hz and the temperature measurement accuracy is ±0.8℃. The cavity pressure sensor is a high-precision piezoelectric sensor with a pressure of 0-20MPa and an accuracy of 0.1%FS. It is embedded in the side wall of the cavity and is used to directly collect the actual cavity pressure of the rubber material under pressure. The crosslinking characteristic sensor adopts a planar capacitive dielectric sensor or a 5MHz longitudinal wave ultrasonic probe; wherein, when the crosslinking characteristic sensor is a planar capacitive dielectric sensor, the electrode spacing is 2mm, the test frequency is 1kHz~10kHz, and it is used to collect the dielectric constant and dielectric loss of the adhesive; when the crosslinking characteristic sensor is a 5MHz longitudinal wave ultrasonic probe, it is used to correct the crosslinking degree value in conjunction with the speed of sound.

[0012] Furthermore, in steps S3 and S4, the online monitoring and closed-loop control of the real-time crosslinking degree are achieved through the following functional units: A data acquisition unit is located at the rubber vulcanization station. The data acquisition unit acquires raw signals of the temperature of the rubber material in the mold, the cavity pressure, the dielectric constant, and the ultrasonic propagation speed through temperature sensors, cavity pressure sensors, and cross-linking characteristic sensors embedded in the mold. A crosslinking degree calculation unit is connected to a data acquisition unit. The crosslinking degree calculation unit has a built-in preset crosslinking model, receives the original signal, and calculates the real-time crosslinking degree value. The crosslinking degree calculation unit adopts a programmable logic controller and has a built-in crosslinking degree calculation module and a standard PID adaptive adjustment function block. The system control cycle is 30s. A data comparison unit, which is connected to the crosslinking degree calculation unit, is used to compare the real-time crosslinking degree with a preset crosslinking degree curve and a deviation threshold, and output a deviation signal. The parameter adjustment execution unit is connected to the data comparison unit and is used to automatically correct the temperature, pressure and holding time of the vulcanizing equipment according to the deviation signal, and feed back the corrected process parameters to the rubber vulcanizing level to form a closed-loop control. The parameter adjustment execution unit includes an electric heating tube duty cycle power control component, a hydraulic proportional relief valve closed-loop pressure regulation component, and an automatic interlocking shutdown safety module for over-temperature, over-pressure and over-sulfurization.

[0013] Furthermore, the vulcanization process is applicable to the flat vulcanization processing of natural rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and blended modified rubber; the temperature and pressure parameters and stage durations of each stage are matched according to the differences in different rubber compound types, product thicknesses and operating conditions. Among them, the induction period of thick products is extended by 20% to 30%, and the heating rate during the acceleration period is reduced to 5℃ / min to 8℃ / min.

[0014] Furthermore, the vulcanization process is tailored to different product types, with temperature and pressure parameters for each stage being matched accordingly. For precision seals, the crosslinking degree deviation threshold is locked at ±3%, and the pressure fluctuation during the stabilization period is controlled within ±0.1 MPa.

[0015] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. Based on the characteristics of the three stages of the rubber crosslinking reaction, this process sets differentiated temperature and pressure parameters for each stage, and ensures that the vulcanization process is always adapted to the crosslinking progress through real-time crosslinking degree monitoring and dynamic feedback adjustment, thereby achieving a precise match between the vulcanization process and the crosslinking progress and avoiding over-vulcanization and under-vulcanization problems. 2. This process can effectively improve the tensile strength, abrasion resistance, and aging resistance of rubber products, and significantly improve the consistency of product quality; 3. This process optimizes the matching of temperature and pressure parameters at each stage, avoiding energy waste caused by overheating in traditional flat vulcanization processes, and significantly reducing production costs; 4. This process is applicable to the production of various rubber materials such as natural rubber, styrene-butadiene rubber, cis-butadiene rubber, and chloroprene rubber, as well as flat vulcanized products such as conveyor belts, seals, and molded rubber sheets; 5. This process does not require large-scale modification of existing conventional flat vulcanizing machines. It only requires the addition of an online crosslinking degree monitoring system and control module. The modification cost is low, the industrial adaptability is strong, and it is easy to implement on a large scale. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0017] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic diagram of the three-stage characteristic curves of the rubber crosslinking reaction of the present invention; Figure 3 This is a schematic diagram of the segmented temperature and pressure parameter variation curves of the present invention; Figure 4 This is a functional unit block diagram of the real-time crosslinking degree online monitoring and closed-loop control system of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0019] Example 1: Segmented Temperature and Pressure Variation Process for the Full-Process Vulcanization of Natural Rubber Conveyor Belt Cover Rubber Flat Sheets This embodiment takes a 2.2mm thin natural rubber conveyor belt cover rubber product as an example to explain in detail the whole process implementation method of the present invention of segmented temperature and pressure vulcanization process following the progress of rubber crosslinking.

[0020] (1) Basic formulation of rubber compound (parts by weight): Natural rubber SMR20: 100 parts; Zinc oxide activator: 5 parts; Stearic acid: 2 parts; Carbon black N330 reinforcing agent: 40 parts; Paraffin oil softener: 5 parts; Accelerator CZ: 0.8 parts; Sulfur crosslinking agent: 2.5 parts; Antioxidant 4010NA: 1 part.

[0021] (2) Pre-mixing process The initial chamber temperature of the internal mixer is 60℃ and the spindle speed is 60rpm. Raw rubber, activator, antioxidant, carbon black and softener are added in sequence and mixed for 8 minutes before the rubber is discharged. After the rubber sheet cools naturally to room temperature, sulfur is added to the open mill and it is mixed evenly 6 times. The sheet thickness is 2.2mm and it is left to stand at room temperature for later use.

[0022] (3) Vulcanization process flow Step S1, crosslinking characteristics calibration of rubber compound: The vulcanization characteristics of the compound are calibrated using a rotorless vulcanizer.

[0023] Sample preparation: From the same batch of internal and open mixing rubber to be tested, cut a circular standard sample with a diameter of 30 mm and a thickness of 6 mm. The mass of each sample is controlled at 5 g to 6 g. The sample surface is free of bubbles, impurities and burrs. After standing at room temperature for 2 hours to eliminate the internal stress of mixing, it is ready for testing.

[0024] Fixed test conditions for the instrument: A closed rotorless vulcanizing instrument was used, with a fixed oscillation frequency of 1.7 Hz and an oscillation amplitude of ±0.5°; the reference test temperature for natural rubber was 150℃.

[0025] Data acquisition rules: The test duration for a single sample is ≥ 1.5 times the normal vulcanization time of the rubber compound. The vulcanization torque-time dynamic curve is fully acquired, and a set of torque data is acquired every 2 seconds.

[0026] Calibration results: Induction period: 0–3.2 min, crosslinking rate: 0.032 min -1 ; Acceleration period: 3.2–12.5 min, crosslinking rate: 0.097 min -1 ; Stabilization period: After 12.5 min, the crosslinking rate is 0.011 min. -1 .

[0027] Step S2, Preset segmented process parameters: Based on the above calibration results, and considering the product thickness of 2.2mm, the rubber compound type of natural rubber, and the application condition of conveyor belt cover rubber, the preset process parameters for each vulcanization stage are as follows: Induction period 0–3.2 min: constant temperature 100℃, constant pressure 3MPa, low temperature and low pressure ensure complete filling of the mold with the rubber compound and prevent scorching; Acceleration period 3.2–12.5 min: temperature linearly increases from 100℃ to 150℃ at a rate of 5.4℃ / min; pressure linearly increases from 3MPa to 12MPa at a rate of 0.97MPa / min. Stabilization period 12.5–15.0 min: constant temperature 150℃, constant pressure 12 MPa, preset endpoint crosslinking degree 92%.

[0028] Step S3, Online monitoring of mold closing: The film is loaded into a flat vulcanizing mold and the mold is closed. The mold is embedded with upper and lower PT100 temperature measuring resistors, side wall voltage pressure sensors, and cavity dielectric sensors. The PLC control cycle is 30 seconds, and a set of in-mold parameters is collected every 10 seconds. The crosslinking degree is calculated in real time by inputting the parameters into the fusion model.

[0029] Step S4, segmented closed-loop temperature and pressure regulation: The sensor sampling frequency is 10s / time, and the deviation threshold is ±4%.

[0030] Closed-loop control status: The workshop ambient temperature is 2℃ lower than the preset value. The measured crosslinking degree at the 6th minute of vulcanization is 4.8% lower than the preset value, exceeding the deviation threshold. The system automatically triggers adjustment: the temperature in the remaining interval of the acceleration period is increased by 3℃, the pressure is increased by 0.5MPa, and the acceleration period duration is extended by 0.8 minutes.

[0031] The adjustment is based on a tiered logic: temperature is adjusted first (increase by 3℃), pressure is adjusted secondarily (increase by 0.5MPa), and the pressure holding time is extended accordingly (0.8min). All parameters are within the safety limits (maximum temperature ≤180℃, maximum pressure ≤90% of the equipment's rated hydraulic pressure).

[0032] Step S5, vulcanization termination, cooling, and demolding: After vulcanization for 15.8 minutes, the system determines that the real-time crosslinking degree has reached the target of 92%, and automatically cuts off the heating power and hydraulic pressure stabilizing oil circuit; the mold is then circulated with water cooling for 5 minutes to continuously cool down. Once the core layer temperature of the product drops below 40°C, the mold is opened and the finished product covered with conveyor belt rubber is removed.

[0033] Comparative Example 1: Traditional Fixed Temperature and Pressure Vulcanization Process The rubber compound formulation, mixing process, and total vulcanization time were exactly the same as in Example 1, with the same total vulcanization time of 15.8 minutes. Process parameters: constant vulcanization temperature of 150℃ and constant cavity pressure of 12MPa throughout the process, without online monitoring or closed-loop correction, and vulcanization was performed with timed shutdowns, which is a standard mass production process in the flat vulcanization industry.

[0034] Performance comparison testing, unified testing standards: Tensile / elongation properties: GB / T 528-2009; Shore A hardness: GB / T 531.1-2008; Akron wear: GB / T 1689-2014; Thermal aging performance: GB / T 3512-2014; Energy consumption: Real-time metering by a smart energy meter in the circuit; Batch stability: The standard deviation of performance was calculated by sampling 20 groups of samples.

[0035] Parallel test performance comparison data:

[0036] Experimental conclusions: Under the same formula, same vulcanization time, and same processing equipment conditions, this invention relies on real-time closed-loop segmented temperature and pressure variation of crosslinking progress to match the exothermic reaction law of rubber compound, which not only avoids the defects of early scorching and late thermal degradation, but also optimizes the density of the three-dimensional crosslinking network of rubber, and simultaneously improves the mechanical, wear-resistant, and aging-resistant properties of the product, reduces production energy consumption, and optimizes batch consistency.

[0037] Example 2: Segmented vulcanization process of styrene-butadiene rubber (SBR1502) This embodiment takes a 2mm conventional sheet styrene-butadiene rubber product as an example, with a target finished product crosslinking degree of 92%.

[0038] After calibration with a rotorless vulcanizing apparatus (reference test temperature 160℃), the segmented process parameters are verified as follows:

[0039] Total vulcanization time: 18.5 min.

[0040] Example 3: Segmented vulcanization process of NBR41 nitrile rubber This embodiment takes a 2mm conventional sheet nitrile rubber product as an example, with a target finished product crosslinking degree of 92%.

[0041] After calibration with a rotorless vulcanizing apparatus (reference test temperature 155℃), the segmented process parameters are verified as follows:

[0042] Total vulcanization time: 17.2 min.

[0043] Example 4: Segmented vulcanization process of chloroprene rubber CR232 This embodiment uses a 2mm conventional sheet of chloroprene rubber as an example, with a target finished product crosslinking degree of 92%.

[0044] After calibration with a rotorless vulcanizing apparatus (reference test temperature 165℃), the segmented process parameters are verified as follows:

[0045] Total vulcanization time: 16.8 min.

[0046] Example 5: Segmented vulcanization process of NR / SBR 70 / 30 blend rubber This embodiment takes a 2mm conventional sheet-like NR / SBR blended rubber product as an example, with a target finished product crosslinking degree of 92%.

[0047] After calibration with a rotorless vulcanizing apparatus (reference test temperature 152℃), the segmented process parameters are verified as follows:

[0048] Total vulcanization time: 16.5 min.

[0049] Product Differentiation Adaptation Supplement Rules: For thick products (conveyor belt core rubber with thickness > 10mm): the induction period is extended by 20% to 30% overall, and the heating rate during the acceleration period is reduced to 5 to 8℃ / min to eliminate the gradient difference between internal and external cross-linking. Precision oil seals and sealing components: cross-linking degree deviation threshold locked at ±3%, and pressure fluctuation control during the stabilization period within ±0.1MPa; Tire tread compound: The maximum pressure limit during acceleration has been increased to 18MPa, and the density of the tread pattern has been enhanced.

[0050] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A segmented temperature and pressure vulcanization process that follows the progress of rubber crosslinking, characterized in that, Includes the following steps: Step S1, crosslinking characteristics calibration of rubber compound: vulcanization characteristics test is carried out on the compound to be processed. Based on the crosslinking reaction rate and the crosslinking degree ratio, the vulcanization is divided into three stages: induction period, acceleration period and stabilization period. The initial temperature and pressure reference parameters for each stage are verified. Step S2, Preset segmented process parameters: Based on the calibration results, combined with the product thickness, rubber compound type and operating conditions, preset the temperature rise curve, pressure rise curve, crosslinking degree threshold and deviation adjustment threshold for each vulcanization stage; Step S3, Online monitoring of mold closing: After the compounded rubber is put into the mold of the flat vulcanizing machine and the mold is closed, the temperature of the rubber material in the mold, the cavity pressure and cross-linking characteristic parameters are collected in real time through the embedded sensing unit in the mold. The main control unit calculates the real-time degree of cross-linking based on the multi-parameter fusion prediction model. Step S4, segmented closed-loop temperature and pressure regulation: compare the real-time crosslinking degree with the preset crosslinking degree threshold. When the deviation exceeds the preset threshold, rely on the closed-loop regulation module to dynamically adjust the heating power of the vulcanizing machine and the hydraulic oil supply pressure in the order of priority: temperature first, pressure second, and pressure holding time last. Perform variable temperature and pressure vulcanization in stages so that the vulcanization process conditions can be adaptively adjusted according to the real-time crosslinking progress of the rubber compound. Step S5, Vulcanization Termination Cooling and Demolding: After the real-time crosslinking degree reaches the preset target value, heating and pressurization are stopped. After controllable cooling until the core layer temperature of the product reaches the standard, the mold is opened and the product is demolded to complete the vulcanization process.

2. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: In step S1, the criteria for dividing the three vulcanization stages are as follows: Induction period: Crosslinking degree 0%~10%, corresponding to the interval from the start of the vulcanization reaction to the sum of the minimum torque value and 10% of the maximum torque increment; Acceleration period: Crosslinking degree 10%~90%, corresponding to the interval from the end of the induction period to the torque reaching the sum of the minimum torque value and 90% of the maximum torque increment; Stable period: The degree of cross-linking is above 90%, which corresponds to the stage where the torque enters the plateau range after the acceleration period ends. The plateau range is defined as the torque fluctuation not exceeding 2% within 1 minute.

3. The segmented temperature and pressure vulcanization process according to claim 2, characterized in that: In step S1, the vulcanization characteristics test is performed using a rotorless vulcanizer or DSC differential scanning calorimetry. The rotorless vulcanizing apparatus method includes: setting a reference test temperature based on the rubber type, using a closed rotorless vulcanizing apparatus under a fixed oscillation frequency of 1.7 Hz and an oscillation amplitude of ±0.5 degrees, acquiring the vulcanizing torque-time dynamic curve, and dividing the three vulcanization stages by torque change characteristics; wherein, the reference test temperature set for the rubber type includes: 150℃ for natural rubber, 160℃ for styrene-butadiene rubber, 155℃ for nitrile rubber, and 165℃ for chloroprene rubber; The DSC differential scanning calorimetry method includes: performing non-isothermal pre-test and isothermal precision test on the compound sample under nitrogen protective atmosphere and nitrogen flow rate of 50 mL / min, characterizing the degree of crosslinking by the ratio of cumulative crosslinking heat release to total crosslinking heat release, and dividing the three vulcanization stages by 10% and 90% heat release ratio.

4. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: In step S3, the real-time crosslinking degree is calculated by a multi-parameter fusion prediction model, and the calculation formula of the multi-parameter fusion prediction model is: ; In the formula, For real-time crosslinking degree, The real-time dielectric constant of the rubber compound. The core layer temperature of the rubber compound. For the real-time pressure of the cavity; , , , The model employs a dual-mode operation of offline calibration and online self-correction, with the calibration coefficients automatically iteratively corrected every 10 vulcanization cycles.

5. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: In step S4, the hierarchical adjustment logic of the closed-loop control module includes: The real-time crosslinking degree is compared with a preset crosslinking degree curve. When the deviation exceeds a preset threshold, a deviation signal is output. The preset threshold is ±3% to ±8% of the crosslinking degree deviation. Based on the deviation signal, the vulcanization process parameters are dynamically adjusted in a standardized step size of ±1℃ for temperature, ±0.3MPa for pressure, or ±20s for holding time, according to the priority order of temperature first, pressure second, and holding time last. Set safety boundaries for parameters, locking the maximum vulcanization temperature to no more than 180℃ and the maximum vulcanization pressure to no more than 90% of the equipment's rated hydraulic pressure, to prevent thermal degradation of the rubber compound and equipment overload.

6. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: In steps S2 and S4, the segmented temperature and pressure control strategy for the three major stages is as follows: Induction period: Maintain a relatively low temperature and low pressure, with the temperature controlled between 80℃ and 120℃ and the pressure controlled between 2MPa and 5MPa, to ensure that the rubber compound fills the mold completely and to prevent early scorching; Acceleration phase: Temperature and pressure gradually increase as the crosslinking reaction progresses. The heating rate is controlled at 5℃ / min to 10℃ / min, and the pressure rate is controlled at 0.5MPa / min to 1.5MPa / min, in order to match the exothermic rate of crosslinking and promote the dense formation of the crosslinking network. Stabilization period: Maintain constant temperature and pressure, with temperature fluctuations controlled within ±1℃ and pressure fluctuations controlled within ±0.2MPa, so that the cross-linking reaction tends to be perfect and the thermal degradation due to oversulfurization is avoided.

7. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: In step S3, the mold-embedded sensing unit includes a temperature sensor, a cavity pressure sensor, and a crosslinking feature sensor. The temperature sensors are two PT100 platinum resistance thermometers, which are embedded in the working surfaces of the upper and lower cavities of the mold, respectively, to simultaneously collect the temperature of the surface and core layers of the rubber material. The sampling frequency is 1Hz and the temperature measurement accuracy is ±0.8℃. The cavity pressure sensor is a high-precision piezoelectric sensor with a pressure of 0-20MPa and an accuracy of 0.1%FS. It is embedded in the side wall of the cavity and is used to directly collect the actual cavity pressure of the rubber material under pressure. The crosslinking characteristic sensor adopts a planar capacitive dielectric sensor or a 5MHz longitudinal wave ultrasonic probe; wherein, when the crosslinking characteristic sensor is a planar capacitive dielectric sensor, the electrode spacing is 2mm, the test frequency is 1kHz~10kHz, and it is used to collect the dielectric constant and dielectric loss of the adhesive; when the crosslinking characteristic sensor is a 5MHz longitudinal wave ultrasonic probe, it is used to correct the crosslinking degree value in conjunction with the speed of sound.

8. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: In steps S3 and S4, the online monitoring and closed-loop control of the real-time crosslinking degree are achieved through the following functional units: A data acquisition unit is located at the rubber vulcanization station. The data acquisition unit acquires raw signals of the temperature of the rubber material in the mold, the cavity pressure, the dielectric constant, and the ultrasonic propagation speed through temperature sensors, cavity pressure sensors, and cross-linking characteristic sensors embedded in the mold. A crosslinking degree calculation unit is connected to a data acquisition unit. The crosslinking degree calculation unit has a built-in preset crosslinking model, receives the original signal, and calculates the real-time crosslinking degree value. The crosslinking degree calculation unit adopts a programmable logic controller and has a built-in crosslinking degree calculation module and a standard PID adaptive adjustment function block. The system control cycle is 30s. A data comparison unit, which is connected to the crosslinking degree calculation unit, is used to compare the real-time crosslinking degree with a preset crosslinking degree curve and a deviation threshold, and output a deviation signal. The parameter adjustment execution unit is connected to the data comparison unit and is used to automatically correct the temperature, pressure and holding time of the vulcanizing equipment according to the deviation signal, and feed back the corrected process parameters to the rubber vulcanizing level to form a closed-loop control. The parameter adjustment execution unit includes an electric heating tube duty cycle power control component, a hydraulic proportional relief valve closed-loop pressure regulation component, and an automatic interlocking shutdown safety module for over-temperature, over-pressure and over-sulfurization.

9. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: The vulcanization process is applicable to the flat vulcanization of natural rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and blended modified rubber; the temperature and pressure parameters and stage durations of each stage are matched according to the differences in different rubber compound types, product thicknesses and operating conditions. Among them, the induction period of thick products is extended by 20% to 30%, and the heating rate during the acceleration period is reduced to 5℃ / min to 8℃ / min.

10. The segmented temperature and pressure vulcanization process according to claim 1, characterized in that: The vulcanization process is tailored to different product types, with temperature and pressure parameters matched at each stage. For precision seals, the crosslinking degree deviation threshold is locked at ±3%, and the pressure fluctuation during the stabilization period is controlled within ±0.1MPa.

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