A rubber vulcanization method and system based on electric heating and temperature-pressure separation control

Abstract

The present application relates to the field of intelligent control technology of tire vulcanization, and particularly relates to a rubber vulcanization method and system based on electric heating and temperature-pressure separation control. The present application realizes independent and accurate control of external temperature by heating the heat transfer medium in the heating tank and driving the upper mold loop and the lower mold loop by the circulating motor respectively; at the same time, the inert gas is filled into the capsule from the gas storage tank, and the pressure control valve is used to close-loop adjust the pressure in the capsule, so as to realize independent control of internal pressure. The temperature difference between the upper mold and the lower mold is calculated and constrained during the vulcanization process, the equivalent vulcanization index based on the representative temperature measuring points on the upper side and the lower side is calculated, and the uniformity difference is calculated. When the limit is exceeded, the temperature setting or the shunt flow of the lagging side is compensated, and the pressure setting is kept unchanged, so as to reduce the vulcanization unevenness and defect risk, improve the consistency of products, and reduce the energy consumption.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology for tire vulcanization, and in particular to a rubber vulcanization method and system based on electric heating and temperature-pressure separation control. Background Technology

[0002] The vulcanization molding of rubber products (especially semi-steel radial tires) typically requires applying both external heat and internal pressure to the tire carcass while the vulcanizing mold is closed. This causes the rubber compound to undergo a cross-linking reaction under specific temperature, time, and pressure conditions, resulting in tread transfer and structural shaping. Current industrial tire vulcanization methods generally employ steam, hot water, or heat transfer media to heat the mold, while a bladder (or water tire) is used to fill the tire carcass with a medium to create internal pressure. This ensures that the tire carcass fully adheres to the mold cavity and achieves densification during the vulcanization cycle. Although this type of process is mature, it still faces multi-dimensional constraints in terms of low carbon and energy saving, process stability and vulcanization uniformity. On the one hand, the steam / hot water system has problems with condensate and drainage control, and the thermal piping and control logic are relatively complex. Moreover, it is easy to introduce temperature disturbances during start-up and shutdown, load fluctuations or parallel operation of multiple machines. On the other hand, the semi-steel tire structure (significant differences in the thickness of the rubber layer and the heat transfer boundary in the sidewall, crown, shoulder, bead, etc.) makes the vulcanization process particularly sensitive to the uniformity of the temperature field and the matching of the pressure curve. Once the temperature gradient or internal pressure fluctuation of the mold increases, it is easy to induce defects such as coexistence of under-vulcanization / over-vulcanization, local bubbles, missing rubber, thin lines, and insufficient tread transfer, thereby affecting the appearance and durability.

[0003] To reduce reliance on steam systems and improve process controllability, an industry-leading approach has emerged using inert gases (such as nitrogen) as the heating / pressurization medium inside tires. The core idea is to control the temperature and pressure of the gas entering the tire's interior space to replace or partially replace steam heating, thereby reducing condensation issues, improving cleanliness, and enhancing energy efficiency. In this direction, Chinese patent document CN101547775A proposes a tire vulcanizing machine and method. By setting separate pressure and temperature control units, it achieves independent control of the nitrogen pressure and temperature supplied to the tire's interior space. Theoretically, this allows for adjustment of the internal pressure (or vice versa) without changing the vulcanization temperature, adapting to the molding and vulcanization requirements of different rubber compounds and tire specifications. However, from an engineering application perspective, this type of independent temperature and pressure control scheme for the internal medium focuses more on improving the degree of control freedom on the gas side inside the tire, and usually still needs to work in conjunction with the heat source system on the mold side. When the external mold heating still uses the traditional steam / hot water system, the difference in the heat transfer links between the upper and lower molds, the hot plate and the shell area may still lead to uneven temperature field. Moreover, when multiple machines are connected in parallel, the heating fluctuates or the heat dissipation conditions of different parts change, it is often difficult to compensate for the temperature difference between the upper and lower parts of the mold and the difference in the vulcanization process of each key part of the tire body by relying solely on independent temperature and pressure control of the gas inside the tire. There are limits to the improvement of vulcanization uniformity.

[0004] Meanwhile, some technologies optimize the pressure curve by using staged pressure variation and combined gas heating to reduce molding defects caused by instantaneous high pressure. For example, Chinese patent document CN115674514A discloses a tire pressure variation vulcanization process and vulcanization system: inert gas is compressed and sent into a pressure storage tank and heated, and then gas is supplied to the vulcanizing bladder to complete the shaping and preheating. During the vulcanization process, it goes through stages such as low-pressure contact softening, gradually increasing the pressure to high pressure, and maintaining the maximum pressure until the end, so as to reduce defects such as missing rubber and air bubbles and improve the yield rate. The advantage of this type of solution is that it matches the process of rubber flow, molding, and densification with the pressure curve in stages, which has certain practicality. However, its control object is still mainly the same inert gas system throughout the preheating and pressurization. Temperature and pressure are easily coupled at the equipment and pipeline level (for example, the same gas, after being heated, affects both temperature and pressure). When there are differences in the temperature field of the external mold or differences in thermal inertia in different areas, relying on staged pressure changes cannot directly solve the problem of asynchronous vulcanization process caused by the temperature difference between the upper and lower molds. In addition, the switching of pressure stages is mostly based on preset timing or experience windows. Under the conditions of changes in raw material batch, ambient temperature, equipment heat dissipation and heat load, there is a lack of online feedback on vulcanization uniformity indicators, resulting in limited adaptability to fluctuating working conditions.

[0005] Furthermore, some existing technologies attempt to combine inert gas vulcanization with external electric heating to simplify thermal piping and improve mold temperature control. Chinese patent document CN116728860A discloses a method and system for all-nitrogen vulcanization of tires: the tire blank is first shaped with low-pressure nitrogen, and then internal temperature nitrogen heat transfer vulcanization and external temperature electric heating are carried out simultaneously (the hot plate and shell areas are adjusted separately). The optimal vulcanization time CT is determined by temperature measurement wires and integral processing based on activation energy to reduce the temperature difference between the upper and lower molds and improve vulcanization uniformity. This scheme introduces external temperature electric heating into the vulcanization process, which theoretically reduces the complexity related to condensate and improves thermal boundary conditions through external temperature zoning. However, from a process control perspective, its key control strategy still tends to rely on offline / semi-offline temperature measurement data to calculate CT and execute according to a predetermined curve, focusing more on vulcanization time setting and external temperature heating methods. For common dynamic disturbances in production (such as differences in mold thermal inertia, asymmetric heat dissipation between upper and lower molds, thermal balance reconstruction caused by switching between different specifications, and temperature fluctuations in the nitrogen circuit), it often lacks a closed-loop compensation mechanism that uses vulcanization uniformity differences as feedback. In addition, existing publicly available schemes usually describe an overall process and system framework. There is still room for further optimization in how to achieve long-term stable decoupling of temperature and pressure circuits at the equipment level, and how to synchronously control the temperature difference constraint between upper and lower molds and the vulcanization process of key parts of the tire carcass throughout the vulcanization process.

[0006] In summary, although existing technologies have made progress in (1) independent temperature and pressure control of inert gas inside the tire, (2) defect suppression of staged pressure change and gas heating, and (3) combination of all-nitrogen vulcanization and external temperature electric heating and CT determination, the following common problems still exist in the scenario of semi-steel tire vulcanization, which is sensitive to thermo-mechanical coupling: First, temperature control and pressure control are easily coupled at the system level, resulting in pressure disturbance when trying to adjust temperature and temperature disturbance when trying to adjust pressure, which is not conducive to the precise matching of complex rubber rheological windows; Second, the temperature difference between the upper and lower parts of the mold and the heat transfer difference in different parts lead to asynchronous vulcanization processes, and existing methods Most existing solutions employ preset curves or stage switching, lacking online closed-loop compensation centered on vulcanization uniformity indicators. Thirdly, while pursuing energy conservation and simplified piping, it is still necessary to consider stable heating and pressure recovery under multi-machine parallel operation, as well as rapid thermal balance reconstruction during switching between different specifications. Based on these reasons, it is still necessary to propose a vulcanization method and system more suitable for engineering mass production. This system should achieve stable separation and control of the temperature and pressure loops under electrically heated external temperatures, and provide an executable process control mechanism to address the key pain points of upper and lower mold temperature difference and vulcanization uniformity, thereby improving vulcanization quality consistency and production stability. Summary of the Invention

[0007] This invention aims to provide a rubber vulcanization method and system based on electric heating and temperature-pressure separation control. By establishing decoupled control between the external temperature electric heating circuit of the mold and the internal pressure inert gas circuit of the bladder, and combining the temperature difference constraint between the upper and lower molds with the vulcanization process uniformity adjustment mechanism, the temperature field and pressure field during vulcanization can be stably controlled and synchronously matched. This reduces the complexity of traditional steam heating and condensate management, while improving the uniformity, appearance quality and batch consistency of semi-steel tire vulcanization, and reducing energy consumption and process fluctuation risks.

[0008] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A rubber vulcanization method based on electric heating and temperature-pressure separation control includes the following steps:

[0010] S1. Establish the upper mold temperature setting curve, lower mold temperature setting curve, and capsule pressure setting curve, and set the upper limit parameter for temperature difference, the upper limit parameter for vulcanization uniformity difference, and the mold closing time parameter. The upper limit parameter for temperature difference is used to limit the temperature difference between the upper mold and the lower mold, the upper limit parameter for vulcanization uniformity difference is used to limit the difference in vulcanization process between the upper and lower sides, and the mold closing time parameter is used to record the vulcanization process time.

[0011] S2, the heat transfer medium is electrically heated by the heating tank, and the heat transfer medium is driven by the circulating motor to enter the upper mold circuit and the lower mold circuit respectively, so that the upper mold and the lower mold are independently heated and preheated to a steady state, and the actual temperature of the upper mold and the actual temperature of the lower mold are collected at the same time.

[0012] S3. After the mold is closed, inert gas is injected into the capsule. The pressure inside the capsule is adjusted through a closed-loop pressure control valve to make it track the capsule pressure setting curve. The pressure is controlled in stages: low pressure for molding, pressure holding during vulcanization, and pressure relief and recovery.

[0013] S4, during the vulcanization stage, the temperature closed loop only adjusts the electric heating power and the diversion flow rate to make the upper mold temperature and the lower mold temperature track the corresponding set curves respectively; the pressure closed loop only adjusts the pressure control valve and does not change the temperature setting; the temperature difference between the upper and lower molds is determined based on the measured temperatures of the upper and lower molds, and the vulcanization index difference is obtained based on the temperatures of the representative temperature measurement points on the upper and lower sides. When the temperature difference between the upper and lower molds or the vulcanization index difference exceeds the limit, only the temperature setting or diversion flow rate on the side lagging behind the vulcanization process is compensated, and the capsule pressure setting curve remains unchanged.

[0014] S5, after reaching the preset vulcanization endpoint, stop heating, depressurize and recover the inert gas to the storage tank through the recovery valve, and reuse it after drying and filtration. Vacuum the capsule to shrink it and open the mold to remove the tire.

[0015] As a further improvement, in step S1, the upper limit parameter of the temperature difference is taken as 1°C to 5°C; the upper limit parameter of the temperature difference is the maximum difference between the measured temperature of the upper mold and the measured temperature of the lower mold allowed during the vulcanization process.

[0016] And / or, in step S2, the heat transfer medium is one or more combinations of heat transfer oil, water and ethylene glycol solution, and the heating tank heats the heat transfer medium to the heat transfer medium outlet temperature range of 150°C to 210°C.

[0017] And / or, in step S2, when the deviation between the measured temperature of the upper mold and the temperature setting curve of the upper mold, and the deviation between the measured temperature of the lower mold and the temperature setting curve of the lower mold both fall within the allowable deviation range of preheating, the process proceeds to tire assembly; wherein, the allowable deviation of preheating is the temperature deviation parameter used to determine whether the preheating of the upper mold and the lower mold has reached a stable state.

[0018] As a further improvement, in step S3, the inert gas is nitrogen. The measured pressure inside the capsule is adjusted by a pressure control valve so that the measured pressure inside the capsule tracks the capsule pressure setting curve and enters the vulcanization pressure window. The measured pressure inside the capsule is the gas pressure inside the capsule detected by the pressure sensor, and the vulcanization pressure window is the pressure range that ensures the tire carcass is molded and shaped and vulcanized under pressure.

[0019] And / or, in step S3, the capsule pressure setting curve includes a shaping low-pressure section and a vulcanization high-pressure section. The shaping low-pressure section has a pressure of 0.04 MPa to 0.20 MPa and a duration of 5 to 30 seconds. The shaping low-pressure section is used to position the embryo, unfold it and expel residual air.

[0020] As a further improvement, in step S4, when the temperature difference between the upper and lower molds exceeds the upper limit parameter, the temperature difference is brought back to the allowable range by adjusting the flow rate or electric heating power of the upper and lower mold circuits; when the vulcanization index difference exceeds the upper limit parameter for vulcanization uniformity difference, the lagging side of the vulcanization process is determined according to the relationship between the equivalent vulcanization index on the upper side and the equivalent vulcanization index on the lower side, and compensation is only made for the temperature setting or flow rate of the lagging side. The temperature closed loop only acts on the actuator of the external temperature electric heating circuit, and the actuator includes at least one or more of the following: an electric heating power adjustment unit, a circulating motor, and a flow proportional valve.

[0021] As a further improvement, in step S4, the temperature closed loop adjusts the electric heating power of the upper mold circuit, the electric heating power of the lower mold circuit, the flow rate of the heat transfer medium in the upper mold circuit, and the flow rate of the heat transfer medium in the lower mold circuit respectively; the flow rates of the heat transfer medium in the upper mold circuit and the flow rate of the heat transfer medium in the lower mold circuit are adjusted by a frequency-controlled circulating motor and a flow-dividing proportional valve.

[0022] And / or, in step S4, the temperatures of representative temperature measuring points on the upper mold side and the lower mold side are collected. Based on the apparent activation energy, gas constant, reference absolute temperature, and temperature changes at each representative temperature measuring point during the vulcanization process, the equivalent vulcanization index on the upper side and the equivalent vulcanization index on the lower side are obtained respectively, and the difference between the two is used to determine the vulcanization uniformity difference. The representative temperature measuring points are the temperature collection locations in the tire crown, tire shoulder, tire sidewall, or the bottom of the lower tire sidewall used to characterize the vulcanization process. The apparent activation energy of the rubber compound is obtained by fitting the vulcanization characteristic time of the corresponding rubber compound at at least three different test temperatures, and the reference absolute temperature is taken from the target vulcanization process temperature or the vulcanization characteristic test temperature of the rubber compound.

[0023] As a further improvement, in step S5, when the equivalent vulcanization index of the slowest vulcanization point reaches the target equivalent vulcanization index, or the maximum vulcanization time is reached, heating is stopped and depressurization and recovery are initiated; the slowest vulcanization point is the tire part with the most delayed vulcanization process, the target equivalent vulcanization index is the index threshold for determining the completion of vulcanization, and the maximum vulcanization time is the longest time allowed to perform vulcanization.

[0024] As a further improvement, a dryer and a filter are installed between the recovery valve and the gas storage tank to ensure that the dew point of the recovered inert gas is below -20°C; wherein, the dew point is the temperature at which the gas begins to condense under the current pressure; and, between step S2 and step S3, a capsule dehumidification step is performed, which includes at least one cycle of filling with inert gas and vacuuming to reduce the moisture content inside the capsule.

[0025] Secondly, the present invention also provides a rubber vulcanization system based on electric heating and temperature-pressure separation control, the system being used to implement the method, the system comprising:

[0026] A vulcanizing machine, comprising a mold and a capsule, the capsule being used to apply internal pressure to the tire carcass;

[0027] A heating tank, comprising an electric heating element, for heating a heat transfer medium;

[0028] A circulating motor is connected to the upper mold circuit and lower mold circuit of the heating tank and the mold, and is used to drive the heat transfer medium to circulate.

[0029] Gas storage tank, used to store inert gases;

[0030] The pressure control valve and pressure sensor are installed on the gas pipeline from the gas tank to the capsule to regulate and detect the actual pressure inside the capsule.

[0031] A temperature sensor group, including at least a temperature sensor for detecting the temperature of the upper mold and the temperature of the lower mold;

[0032] The controller is communicatively connected to the electric heating component, the circulating motor, the pressure control valve, the pressure sensor, and the temperature sensor group, respectively. The controller is configured to execute steps S1 to S5 to achieve decoupled control of the temperature closed loop and the pressure closed loop.

[0033] Preferably, the upper mold circuit and the lower mold circuit are respectively equipped with flow-dividing proportional valves to independently adjust the flow rate of the upper mold circuit and the flow rate of the lower mold circuit; the flow rate of the upper mold circuit is the flow rate of the heat transfer medium entering the upper mold circuit, and the flow rate of the lower mold circuit is the flow rate of the heat transfer medium entering the lower mold circuit.

[0034] And / or, the system further includes a recovery pipeline and a recovery valve, the recovery pipeline connecting the capsule and the gas storage tank, and the recovery valve being used to control the inert gas discharged from the capsule during the depressurization phase to enter the filter, dryer and be recovered to the gas storage tank;

[0035] And / or, the controller is configured to adjust the upper mold temperature setting curve, the lower mold temperature setting curve, the upper mold loop flow rate, or the lower mold loop flow rate online according to the vulcanization uniformity difference, so that the vulcanization uniformity difference does not exceed the upper limit parameter of the vulcanization uniformity difference; wherein, the vulcanization uniformity difference is the difference between the upper equivalent vulcanization index and the lower equivalent vulcanization index.

[0036] Thirdly, the present invention also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the method.

[0037] Fourthly, the present invention also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the method.

[0038] This invention decouples the electric heating circuit for the external temperature of the mold from the inert gas pressure circuit for the internal pressure of the bladder during the entire vulcanization process. This achieves process control where temperature can be independently and precisely adjusted, and pressure can be independently and stably tracked. This prevents pressure fluctuations from amplifying factors such as asymmetry of the upper and lower thermal boundaries of the mold and differences in heat transfer between different parts. Furthermore, by controlling the temperature difference between the upper and lower molds… By constraining and compensating for differences in the vulcanization process by controlling the difference between the measured temperature of the upper mold and the lower mold, the risk of under-vulcanization / over-vulcanization caused by uneven vulcanization can be significantly reduced. This makes the vulcanization degree of key areas such as the tire crown, tire shoulder, and tire sidewall more consistent, thereby reducing typical defects such as bubbles, missing rubber, unclear tread patterns, local scorching, and dimensional fluctuations, and improving appearance quality and first-pass yield. At the same time, electric heating replaces or reduces the steam heating link, reduces the complexity of condensate and drainage management, reduces pipeline corrosion and scaling, and provides faster start-up and shutdown response and higher temperature stability. Combined with inert gas recovery circulation, heat loss and medium consumption can be reduced. This comprehensively achieves reduced energy consumption, more controllable vulcanization cycle, reduced equipment maintenance costs, and improved batch consistency and production stability. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the rubber vulcanization system based on electric heating and temperature-pressure separation control according to the present invention.

[0040] Figure 2 This is a schematic diagram of the rubber vulcanization method of the present invention.

[0041] Figure 3 This is a schematic diagram of the decoupled control architecture for temperature and pressure separation in this invention.

[0042] Figure 4 This is a schematic diagram of the logic for constraining the temperature difference between the upper and lower molds and compensating for vulcanization uniformity in this invention.

[0043] Figure 5 This is a schematic diagram of the stages of the temperature setting curve and pressure setting curve of the present invention.

[0044] Figure 6 This is a schematic diagram of the inert gas recovery and drying filtration process of the present invention.

[0045] Figure 7 This is a comparison chart of DIN wear and rolling resistance between the present invention and a comparative example.

[0046] Figure 8 This is a comparison chart of the energy consumption of a single tire in this invention and a comparative example.

[0047] Figure 9 This is a comparison chart of the vulcanization time, mold opening and closing time, and total cycle time between the present invention and a comparative example.

[0048] Figure 10The temperature difference between the upper and lower sides of the tire body in this invention and the comparative example. Curve comparison chart.

[0049] Figure 11 This is a comparison chart of the road test wear rate and the expected mileage of the present invention.

[0050] Figure 12 This is a comparison diagram of the swelling degree of different anatomical parts of the present invention and the comparative example. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. Equivalent substitutions or conventional adjustments made by those skilled in the art to the type of heat transfer medium, valve type, sensor arrangement, controller model, temperature setting curve, capsule pressure setting curve, and vulcanization process parameters without departing from the concept of the present invention should all fall within the scope of protection of the present invention.

[0052] I. Terminology Explanation

[0053] Temperature and pressure separation control refers to setting the external temperature control of the mold and the internal pressure control of the bladder as independent closed-loop control processes during rubber vulcanization. The temperature closed loop only acts on the external temperature electric heating circuit, and the pressure closed loop only acts on the internal pressure circuit of the bladder; the pressure control process does not change the upper mold temperature setting curve and the lower mold temperature setting curve, and the temperature control process does not change the bladder pressure setting curve.

[0054] An external temperature electric heating circuit refers to a heat transfer system that provides heat to the mold through a heating tank, electric heating components, a circulating motor, a flow divider valve group, an upper mold circuit, and a lower mold circuit. This circuit is mainly used to control the temperature of the upper mold and the lower mold.

[0055] The capsule internal pressure circuit refers to the gas pressure control system formed by the gas storage tank, pressure control valve, pressure sensor, capsule, recovery valve, filter, dryer, and recovery pipeline. This circuit is mainly used to provide the internal pressure required for capsule shaping and vulcanization.

[0056] The upper mold circuit refers to the circulation branch where the heat transfer medium enters the upper mold or the corresponding hot plate area of ​​the upper mold. The lower mold circuit refers to the circulation branch where the heat transfer medium enters the lower mold or the corresponding hot plate area of ​​the lower mold. The upper and lower mold circuits are each equipped with a flow-dividing adjustment mechanism to achieve independent adjustment of the heat exchange intensity between the upper and lower molds.

[0057] The temperature difference between the upper and lower molds refers to the difference between the measured temperature of the upper mold and the measured temperature of the lower mold. It is used to determine whether the external temperature field of the mold is uniform and serves as a constraint for the coordinated adjustment of the temperature closed loop.

[0058] The equivalent sulfurization index is an indicator of the cumulative degree of sulfurization reaction calculated based on the temperature history of representative temperature measurement points. The upper equivalent sulfurization index is used to characterize the sulfurization process of the upper representative area, and the lower equivalent sulfurization index is used to characterize the sulfurization process of the lower representative area.

[0059] Poor vulcanization uniformity refers to the difference between the equivalent vulcanization index on the upper side and the equivalent vulcanization index on the lower side. It is used to determine whether the vulcanization process on the upper and lower sides of the tire is synchronized and serves as the triggering basis for lag compensation.

[0060] The lag side refers to the side with the lower equivalent sulfurization index at the same sulfurization time. When the equivalent sulfurization index of the lower side is lower than that of the upper side, the lower side is the lag side; when the equivalent sulfurization index of the upper side is lower than that of the lower side, the upper side is the lag side.

[0061] The preset vulcanization endpoint refers to the vulcanization termination conditions determined based on the target equivalent vulcanization index, maximum vulcanization time, target rubber vulcanization characteristics, and product quality requirements.

[0062] II. System Structure

[0063] like Figure 1 As shown, the rubber vulcanization system based on electric heating and temperature-pressure separation control of the present invention includes a vulcanizing machine, an external temperature electric heating circulation system, an inert gas pressure system, a detection and sensing system, and a controller.

[0064] The vulcanizing machine includes a mold and a bladder. The mold includes an upper mold and a lower mold, which together form the tire vulcanizing cavity for shaping and transferring the tread pattern on the outer surface of the tire carcass. The bladder is placed inside the tire carcass and expands during vulcanization by being pressurized with inert gas, providing uniform support to the inner side of the tire carcass and ensuring full fit with the mold cavity. The vulcanizing machine may also include a hot plate, a central mechanism, a mold closing mechanism, and a mold opening and closing drive mechanism. This part is a conventional structure of tire vulcanizing machines and will not be described in detail in this embodiment.

[0065] The external temperature electric heating circulation system includes a heating tank, an electric heating element, a circulating motor, a flow divider valve assembly, an upper mold circuit, and a lower mold circuit. The heating tank contains and heats the heat transfer medium, which can be one or more combinations of heat transfer oil, water, and ethylene glycol solution. The electric heating element is located inside the heating tank or connected to it for heat exchange, and is used to convert electrical energy into heat energy. The circulating motor drives the circulation of the heat transfer medium. The flow divider valve assembly distributes the heat transfer medium to the upper mold circuit and the lower mold circuit respectively. The upper mold circuit is connected to the upper mold or its hot plate for heat exchange, and the lower mold circuit is connected to the lower mold or its hot plate for heat exchange. By adjusting the circulating motor speed, the opening of the flow divider valve assembly, and the electric heating power, the heat exchange intensity of the upper and lower molds can be controlled separately.

[0066] The inert gas pressure system includes a gas storage tank, a pressure control valve, a pressure sensor, a bladder inflation line, a recovery valve, a filter, a dryer, and a recovery line. The gas storage tank stores inert gas, preferably nitrogen. The pressure control valve, located between the gas storage tank and the bladder, regulates the gas flow rate into the bladder. The pressure sensor detects the pressure inside the bladder or the pressure on the bladder's inlet side. The recovery line recovers the inert gas discharged from the bladder back to the gas storage tank after vulcanization. The filter removes oil mist, particles, or impurities from the gas. The dryer reduces the moisture content of the recovered gas. The recovery valve controls the opening and closing of the recovery line.

[0067] like Figure 6 As shown, inert gas passes through the recovery valve, filter, and dryer in sequence in the normal recovery path before entering the gas storage tank; under abnormal conditions, some gas can be discharged to the discharge port through the bypass valve to protect the safety of the gas recovery system.

[0068] The detection sensing system includes at least an upper mold temperature sensor, a lower mold temperature sensor, an upper representative temperature sensor, a lower representative temperature sensor, and a pressure sensor. The upper mold temperature sensor detects the actual temperature of the upper mold, and the lower mold temperature sensor detects the actual temperature of the lower mold. The upper and lower representative temperature sensors can be placed in corresponding areas of the test tire blank or test mold, or they can be estimated during mass production using mold temperature, circuit supply and return oil temperatures, and a heat transfer model. Representative temperature points can be selected from locations sensitive to the vulcanization process, such as the tire crown, shoulder, sidewall, or the bottom of the lower sidewall.

[0069] The controller can be a PLC, industrial computer, or embedded controller. The controller communicates with the electric heating assembly, circulating motor, flow divider valve assembly, pressure control valve, recovery valve, temperature sensor, and pressure sensor. For example... Figure 3 As shown, the controller internally includes at least a temperature closed-loop control module, a pressure closed-loop control module, a temperature difference constraint module, a vulcanization uniformity compensation module, and a recovery control module. The temperature closed-loop control module only outputs control commands to the electric heating assembly, the circulating motor, and the flow divider valve assembly; the pressure closed-loop control module only outputs control commands to the pressure control valve, the recovery valve, or the vacuum valve. Thus, temperature control and pressure control are decoupled in both hardware actuators and control logic.

[0070] III. Specific Technical Route for Implementing the Method of the Invention

[0071] like Figure 2 As shown, the method of the present invention includes steps S1 to S5.

[0072] S1, Parameter Setting and Initialization

[0073] Before vulcanization begins, the controller establishes upper mold temperature setting curves, lower mold temperature setting curves, and bladder pressure setting curves based on the target tire specifications, rubber compound system, mold structure, and process requirements. The upper mold temperature setting curve specifies the change of the target upper mold temperature over time during vulcanization, the lower mold temperature setting curve specifies the change of the target lower mold temperature over time during vulcanization, and the bladder pressure setting curve specifies the change of the pressure inside the bladder over time.

[0074] The controller also sets upper limits for temperature difference, vulcanization uniformity, and mold closing timing. The upper limit for temperature difference limits the maximum difference between the measured temperatures of the upper and lower molds. Preferably, the upper limit for temperature difference is between 1°C and 5°C, more preferably 3°C. The upper limit for vulcanization uniformity limits the difference in vulcanization progress between the upper and lower sides. The mold closing timing records the vulcanization process time from the moment mold closing is completed or the shaping begins.

[0075] The temperature difference between the upper and lower molds can be calculated as follows:

[0076] ;

[0077] in, This refers to the temperature difference between the upper and lower molds. The actual temperature of the upper mold; The actual measured temperature of the lower mold; This is the timing variable after the model is combined.

[0078] To characterize the uniformity of vulcanization, the controller can calculate the upper equivalent vulcanization index and the lower equivalent vulcanization index based on the temperatures of the upper and lower representative temperature measurement points, respectively. The equivalent vulcanization index can be expressed as follows:

[0079] ;

[0080] in, For the first The side represents the region at time. The equivalent sulfurization index; Indicates the upper or lower side; For the first The side represents the temperature measurement point at time. The corresponding equivalent vulcanization reaction rate; This is the cumulative start time of sulfidation; This is the time variable for integration.

[0081] The equivalent vulcanization reaction rate can be obtained from vulcanization characteristic tests of the corresponding rubber compound. Specifically, a rotorless vulcanizer or a flatbed vulcanizer can be used to measure the vulcanization time of the rubber compound at at least three different test temperatures to establish the correlation between temperature and vulcanization reaction rate. During mass production control, the controller uses a table or calculation based on the temperature history of representative temperature measurement points to obtain the equivalent vulcanization increment for each sampling period and accumulates it.

[0082] Poor vulcanization uniformity can be calculated as follows:

[0083] ;

[0084] in, Due to poor uniformity of vulcanization; The upper side is the equivalent sulfurization index; The lower side is the equivalent sulfurization index; This represents the absolute value of the difference.

[0085] Through the above initialization steps, clear temperature targets, pressure targets, temperature difference constraint targets, and vulcanization uniformity targets can be established before vulcanization begins, providing a foundation for subsequent closed-loop control.

[0086] S2, External Temperature Circuit Established

[0087] like Figure 1 and Figure 5 As shown, step S2 is used to establish a stable external temperature electric heating circuit before mounting the tire or closing the mold. The controller starts the electric heating component in the heating tank to heat the heat transfer medium and starts the circulation motor to make the heat transfer medium circulate between the heating tank, the flow divider valve group, the upper mold circuit and the lower mold circuit.

[0088] During the preheating phase, the diversion valve assembly supplies the heat transfer medium to the upper mold circuit and the lower mold circuit according to the initial opening. The controller reads the feedback values ​​from the upper mold temperature sensor and the lower mold temperature sensor, and determines whether the measured temperatures of the upper mold and the lower mold are within the allowable deviation range of the corresponding set curves. When the deviations between the measured temperatures of the upper mold and the set temperature curves of the upper mold, and the deviations between the measured temperatures of the lower mold and the set temperature curves of the lower mold, are both within the allowable preheating deviation range, and after a preset stabilization time, the preheating of the external temperature circuit is considered complete.

[0089] The allowable preheating deviation can be set according to the tire specifications and the thermal inertia of the mold, for example, from 0.5℃ to 2℃. The outlet temperature of the heat transfer medium can be set from 150℃ to 210℃. If the upper mold temperature rises faster than the lower mold temperature, the controller can reduce the flow distribution ratio of the upper mold circuit or increase the flow distribution ratio of the lower mold circuit; if the lower mold temperature rises faster than the upper mold temperature, the opposite adjustment is performed. In this way, the initial temperature difference between the upper and lower molds can be reduced before tire assembly, creating a stable thermal boundary for subsequent vulcanization uniformity control.

[0090] S3, Internal pressure circuit established.

[0091] Step S3 is used to establish the internal pressure circuit of the capsule and complete the preform shaping. After mold closing, the controller opens the pressure control valve, allowing inert gas from the gas storage tank to enter the capsule. Preferably, the inert gas is nitrogen. The pressure sensor detects the actual pressure inside the capsule in real time, and the controller adjusts the opening of the pressure control valve according to the capsule pressure setting curve to ensure a smooth increase in pressure inside the capsule.

[0092] The bladder pressure setting curve may include a low-pressure setting section, a high-pressure vulcanization section, and a pressure relief and recovery section. The low-pressure setting section, with a pressure of 0.04 MPa to 0.20 MPa and a duration of 5 to 30 seconds, is used to initially unfold, position, and expel residual air from the tire carcass. After setting, the controller increases the pressure inside the bladder to the vulcanization pressure window according to the pressure ramp. The vulcanization pressure window is determined based on the tire size and the bladder's pressure-bearing capacity; for example, a bladder pressure of approximately 2.10 MPa may be used for semi-steel tires.

[0093] Between steps S2 and S3, a capsule dehumidification step can also be performed, which involves at least one cycle of filling with inert gas and vacuuming to reduce residual moisture inside the capsule. This step helps to reduce the impact of moisture on pressure stability and capsule movement during the vulcanization process.

[0094] S4, Temperature and Pressure Separation Closed-Loop Vulcanization Control

[0095] Step S4 is the core control step of this invention. For example... Figure 3 and Figure 4 As shown, during the vulcanization stage, the controller simultaneously performs temperature closed-loop, pressure closed-loop, upper and lower mold temperature difference constraint, and vulcanization uniformity compensation.

[0096] The temperature closed loop operates only on the external temperature electric heating circuit. The controller adjusts the electric heating power, circulation flow rate, or flow divider valve opening of the upper mold circuit based on the deviation between the upper mold temperature setpoint curve and the actual measured temperature of the upper mold; similarly, it adjusts the electric heating power, circulation flow rate, or flow divider valve opening of the lower mold circuit based on the deviation between the lower mold temperature setpoint curve and the actual measured temperature of the lower mold. The temperature closed loop controls the upper and lower mold temperatures and does not directly change the capsule pressure setpoint curve.

[0097] The pressure closed loop operates only on the capsule internal pressure circuit. The controller adjusts the opening of the pressure control valve based on the deviation between the capsule pressure setpoint curve and the actual measured pressure inside the capsule, ensuring that the internal pressure tracks the capsule pressure setpoint curve. The pressure closed loop controls only the internal pressure of the capsule and does not directly alter the upper mold temperature setpoint curve, lower mold temperature setpoint curve, electric heating power setting, or flow rate setting. Therefore, this invention avoids the coupling problem of "temperature adjustment affecting pressure, and pressure adjustment affecting temperature" inherent in traditional steam vulcanization processes from a control logic perspective.

[0098] Regarding the temperature difference constraint between the upper and lower molds, the controller calculates the temperature difference in real time. When the temperature difference exceeds the upper limit parameter, the controller prioritizes coordinating the flow rates of the upper and lower mold circuits. For example, when the upper mold temperature is higher than the lower mold temperature and exceeds the upper limit parameter, the controller increases the flow rate of the lower mold circuit or decreases the flow rate of the upper mold circuit; conversely, when the lower mold temperature is higher than the upper mold temperature and exceeds the upper limit parameter, the controller increases the flow rate of the upper mold circuit or decreases the flow rate of the lower mold circuit. If necessary, the controller can also limit the electric heating power of the upper or lower mold to prevent the temperature difference from expanding further.

[0099] Regarding vulcanization uniformity compensation, the controller accumulates the upper and lower equivalent vulcanization indices based on the temperatures of the upper and lower representative temperature measurement points, respectively, and calculates the vulcanization uniformity difference. When the vulcanization uniformity difference exceeds the upper limit parameter, the controller determines the lag side based on the relationship between the upper and lower equivalent vulcanization indices. When the lower equivalent vulcanization index is lower than the upper equivalent vulcanization index, the lower side is the lag side, and the controller increases the lower mold temperature setting or increases the lower mold circuit flow rate; when the upper equivalent vulcanization index is lower than the lower equivalent vulcanization index, the upper side is the lag side, and the controller increases the upper mold temperature setting or increases the upper mold circuit flow rate.

[0100] During the compensation process, the controller maintains the capsule pressure setpoint curve unchanged. In other words, vulcanization uniformity compensation is not achieved by changing the capsule pressure, but rather through localized heat compensation via the external temperature electric heating circuit. This improves the vulcanization process on the lagging side without disrupting the stability of the molding pressure and capsule pressure. Compensation prioritizes flow rate regulation; if the flow rate reaches the set upper limit and still fails to reduce the vulcanization uniformity difference, the lagging side temperature setting is then slightly adjusted. The compensation process sets a maximum compensation amplitude and slope to avoid localized overheating or over-vulcanization. Once the vulcanization uniformity difference falls below the upper limit parameter and remains below it for a preset time, the controller exits the compensation state and resumes normal temperature tracking control.

[0101] like Figure 5 As shown, during the vulcanization stage, the upper mold temperature, lower mold temperature, and bladder pressure operate according to their respective set curves. The upper and lower mold temperatures are mainly controlled by the external electric heating circuit, while the bladder pressure is mainly controlled by the pressure control valve. Because the two control circuits are separate, this invention can optimize the temperature and pressure curves separately within the same vulcanization cycle, thereby taking into account the uniformity of the vulcanization reaction, the quality of the tire carcass fitting to the mold, and energy consumption control.

[0102] S5, vulcanization completion, recycling and mold opening

[0103] When the preset vulcanization endpoint is met, the controller stops heating or reduces the electric heating power to a heat preservation state and enters the pressure relief and recovery phase. The preset vulcanization endpoint can be either the equivalent vulcanization index at the slowest vulcanization point reaching the target equivalent vulcanization index, or the maximum vulcanization time being reached. The slowest vulcanization point refers to the tire part where the vulcanization process is most delayed, the target equivalent vulcanization index is the index threshold for determining the completion of vulcanization, and the maximum vulcanization time is the maximum time allowed for vulcanization.

[0104] like Figure 6 As shown, during the depressurization stage, the recovery valve is opened, and the inert gas inside the capsule enters the filter and dryer through the recovery valve, and is then recovered to the storage tank. The filter is used to remove oil mist and particles, and the dryer is used to reduce the moisture content of the gas. Preferably, the dew point of the recovered inert gas is below -20°C. When the capsule pressure drops to a safe threshold, the controller initiates a vacuuming action, causing the capsule to contract, and then the mold is opened and the capsule is removed. Thus, this invention not only reduces inert gas consumption, but also reduces the impact of condensate and secondary vaporization on the stability of mold opening and closing.

[0105] IV. Examples and Comparative Examples

[0106] The following examples and comparative examples are used to illustrate the technical effects of the present invention and are not intended to limit the scope of protection of the present invention. In the tests, unless otherwise specified, the examples and comparative examples used the same specifications of tires, the same tire blanks, the same molds, and the same testing aperture.

[0107] Example 1: Vulcanization using the electric heating and temperature-pressure separation control method of the present invention.

[0108] use Figure 1 The system shown performs vulcanization of semi-steel tires. The target tire specification is 235 / 70R16SU318, and the tread compound is J157 carbon black tread compound. The external temperature electric heating circuit includes a heating tank, a circulating motor, a flow divider valve group, an upper mold circuit, and a lower mold circuit; the bladder internal pressure circuit includes an air tank, a pressure control valve, a pressure sensor, the bladder, and a recovery pipeline.

[0109] according to Figure 2 The process shown performs vulcanization. In step S1, the upper mold temperature setting curve, lower mold temperature setting curve, and capsule pressure setting curve are established, and the upper limit parameter for temperature difference is set to 3℃. In step S2, the heat transfer medium is electrically heated through a heating tank, and a circulating motor drives the heat transfer medium into the upper mold circuit and lower mold circuit respectively, preheating the upper and lower molds to a steady state. In step S3, after mold closing, nitrogen gas is injected into the capsule, and the pressure of the electro-vulcanizing capsule is 2.10MPa. In step S4, according to... Figure 3 and Figure 4 The process involves temperature and pressure separation closed-loop vulcanization control. In step S5, after vulcanization, the pressure is released, nitrogen is recovered, the bladder is evacuated and the mold is opened to remove the tire.

[0110] Comparative Example 1: Vulcanization process using steam and nitrogen

[0111] Comparative Example 1 employed a conventional steam-nitrogen vulcanization process. The tire specifications, tire blanks, molds, and testing methods were the same as in Example 1. During vulcanization, 1.65 MPa steam was used in conjunction with 2.10 MPa nitrogen. In this comparative example, condensation may occur during the steam vulcanization heat exchange process, and the coupling between temperature and pressure control is relatively high.

[0112] (a) Comparison of temperature differences between the upper and lower sides of the fetus

[0113] like Figure 10 As shown, Example 1 and Comparative Example 1 respectively collected the temperature difference between the upper and lower sides of the tire body, representing temperature measurement points. The temperature difference inside the tire body is defined as follows:

[0114] ;

[0115] in, This refers to the temperature difference between the upper and lower sides of the fetus. Temperature measured at the upper part of the tire body; Temperature measured at a point on the lower side of the tire body; This refers to the test time.

[0116] according to Figure 10 Based on the corresponding data calculations, the minimum internal temperature difference in Example 1 was approximately 1.8℃, the maximum was approximately 3.9℃, and the average was approximately 2.43℃; the minimum internal temperature difference in Comparative Example 1 was approximately 3.6℃, ​​the maximum was approximately 14.4℃, and the average was approximately 8.99℃. Compared to Comparative Example 1, the average internal temperature difference in Example 1 was reduced by approximately 72.97%. The calculation method is as follows:

[0117] ;

[0118] in, This represents the average rate of decrease in temperature difference within the tire cavity. The average internal temperature difference of the tire in Comparative Example 1; The average internal temperature difference of the tire in Example 1.

[0119] Depend on Figure 10 It is known that the present invention can significantly reduce the temperature difference between the upper and lower sides of the tire body, making the vulcanization heat process in key areas of the tire body more consistent.

[0120] (II) Comparison of DIN wear and rolling resistance

[0121] like Figure 7 As shown, the bench performance of Example 1 and Comparative Example 1 was tested. The results are as follows:

[0122]

[0123] The DIN wear reduction rate is calculated as follows:

[0124] ;

[0125] in, To reduce DIN wear rate; DIN wear is for comparative example 1; The DIN wear is for Example 1.

[0126] The calculation method for the rolling resistance reduction rate is as follows:

[0127] ;

[0128] in, The rolling resistance reduction rate; The rolling resistance is for Comparative Example 1; The rolling resistance is that of Example 1.

[0129] Depend on Figure 7 It can be seen that after adopting the present invention, both DIN wear and rolling resistance are reduced, indicating that the present invention improves wear resistance and reduces rolling resistance by improving vulcanization uniformity and rubber density.

[0130] (III) Energy Consumption Conversion Comparison

[0131] like Figure 8 As shown, energy consumption is calculated using a standard tire weighing 10kg as a reference. The energy consumption per tire for the steam process in Comparative Example 1 is calculated to be 2.03 yuan / tire, while the energy consumption per tire for the process of the present invention in Example 1 is calculated to be 1.24 yuan / tire. Compared to Comparative Example 1, the energy consumption per tire in Example 1 is reduced by approximately 38.92%.

[0132] The calculation method for the energy consumption reduction rate is as follows:

[0133] ;

[0134] in, Energy consumption reduction rate; This is the converted energy consumption value per tire for Comparative Example 1; This is the converted energy consumption value per tire in Example 1.

[0135] Depend on Figure 8 It is evident that the present invention can significantly reduce the operating cost of vulcanization by employing an electric heating external temperature circuit and reducing losses related to steam condensate.

[0136] (iv) Comparison of vulcanization time and production cycle

[0137] like Figure 9 As shown, the vulcanization time, mold opening and closing time, and total time for Comparative Example 1 and Example 1 are as follows:

[0138]

[0139] Specifically, the vulcanization time was shortened by 24 seconds, the mold opening and closing time was shortened by 44 seconds, and the total time was shortened by 68 seconds. It is evident that this invention not only shortens the vulcanization time of the main body but also significantly reduces the mold opening and closing time. This is because this invention does not use steam directly as the main external heat source, reducing the impact of condensate, secondary vaporization, and capsule movement lag on the mold opening and closing process.

[0140] (V) Comparison of road test wear performance

[0141] like Figure 11 As shown, full-vehicle road tests were conducted on Example 1 and Comparative Example 1. The test vehicles were front-wheel drive Fenglanda vehicles, with the front and rear wheels swapped approximately every 1000 km. The sample specifications were 235 / 70R16SU318, and the tread compound was J157 carbon black tread compound. The test mileage was 12000 km. The test results are as follows:

[0142]

[0143] The wear rate of groove depth can be calculated as follows:

[0144] ;

[0145] in, This refers to the wear amount at the groove depth. This represents the original trench depth. The depth of the trench after the experiment.

[0146] The mileage per unit trench depth can be calculated as follows:

[0147] ;

[0148] in, The unit is the mileage of the trench depth; For testing mileage; This refers to the wear amount at the groove depth.

[0149] The estimated mileage can be calculated as follows:

[0150] ;

[0151] in, For estimated mileage; The unit is the mileage of the trench depth; This represents the original trench depth. This refers to the wear limit groove depth.

[0152] Depend on Figure 11As can be seen, in the front tire position, the wear rate of the sample produced by the process of the present invention decreased from 17.2% to 15.7%, and the expected mileage increased from 69,666 km to 76,653 km, an increase of approximately 10.03%; in the rear tire position, the wear rate of the sample produced by the process of the present invention decreased from 10.4% to 9.4%, and the expected mileage increased from 104,107 km to 127,293 km, an increase of approximately 22.27%. These results demonstrate that the present invention can improve tire wear performance under actual road conditions.

[0153] (vi) Comparison of anatomical swelling degree

[0154] like Figure 12 As shown, samples were taken from the tires of Example 1 and Comparative Example 1, and the swelling degree of the rubber compound in different parts was tested. The swelling degree can be calculated as follows:

[0155] ;

[0156] in, Swelling degree; The dry mass of the sample; This is the mass of the sample after swelling equilibrium.

[0157] The test results are as follows:

[0158]

[0159] The corresponding vulcanization pressure conditions are as follows: In Example 1, the pressure of the electro-vulcanizing capsule is 2.10 MPa; in Comparative Example 1, the steam vulcanization conditions are 1.65 MPa steam combined with 2.10 MPa nitrogen.

[0160] from Figure 12 As shown in the table, the swelling degree of Example 1 at the tread, upper sidewall, lower sidewall, upper outer sheath, and lower outer sheath locations is lower than that of Comparative Example 1. Specifically, the tread swelling degree decreased from 2.21 to 2.08, a reduction of approximately 5.88%; the upper sidewall swelling degree decreased from 3.25 to 2.90, a reduction of approximately 10.77%; the lower sidewall swelling degree decreased from 3.14 to 2.94, a reduction of approximately 6.37%; the upper outer sheath swelling degree decreased from 2.06 to 2.02, a reduction of approximately 1.94%; and the lower outer sheath swelling degree decreased from 2.08 to 2.05, a reduction of approximately 1.44%. The swelling degree at the lower triangle location is the same for both examples, at 1.72; the swelling degree at the upper triangle location is 1.83 for Example 1 and 1.72 for Comparative Example 1, showing local differences, but overall does not affect the trend of improved vulcanization density exhibited by the present invention in the main tread, sidewall, and outer sheath locations.

[0161] Depend on Figure 12It can be seen that the present invention improves the cross-linking density of the rubber compound in key parts by controlling temperature and pressure separation, constraining the temperature difference between the upper and lower molds, and compensating for vulcanization uniformity, which helps to reduce performance fluctuations caused by uneven vulcanization in different areas of the tire carcass.

[0162] Combination Figures 7 to 12 The test results show that the present invention has at least the following technical advantages over the traditional steam-nitrogen sulfidation process:

[0163] First, the present invention separates the external temperature electric heating circuit from the capsule internal pressure circuit for control, so that temperature control and pressure control do not interfere with each other, thereby improving the stability of the vulcanization process.

[0164] Secondly, by constraining the temperature difference between the upper and lower molds, the present invention reduces the average temperature difference between the upper and lower sides of the tire body from about 8.99°C to about 2.43°C, and the average temperature difference within the tire body is reduced by about 72.97%, which significantly improves the consistency of the vulcanization heat process.

[0165] Third, the present invention makes the vulcanization process on the upper and lower sides more synchronized by compensating for the hysteresis side based on the poor uniformity of vulcanization, thereby reducing the risk of both under-vulcanization and over-vulcanization.

[0166] Fourth, in terms of bench performance, the present invention reduces DIN wear by approximately 9.02% and rolling resistance by approximately 2.44%, indicating that the present invention has an improving effect on both wear resistance and low rolling resistance performance.

[0167] Fifth, in terms of energy consumption, this invention reduces the energy consumption per tire from 2.03 yuan / tire to 1.24 yuan / tire, a reduction of approximately 38.92%, demonstrating a significant energy-saving effect.

[0168] Sixth, in terms of production cycle time, the present invention reduces the total time from 838s to 770s, a reduction of approximately 8.11%, of which the mold opening and closing time is reduced from 90s to 46s, a reduction of approximately 48.89%.

[0169] Seventh, in terms of road test wear, the expected mileage of the front tires increased from 69,666 km to 76,653 km, and the expected mileage of the rear tires increased from 104,107 km to 127,293 km, indicating that the present invention can also improve wear performance under actual road conditions.

[0170] In summary, this invention can achieve stable temperature field, stable pressure field, and consistent vulcanization process in the rubber vulcanization process without relying on traditional steam external temperature main heat source. This is achieved through an electric heating external temperature circuit, a capsule internal pressure circuit, temperature and pressure separation closed-loop control, upper and lower mold temperature difference constraint, and vulcanization uniformity compensation. This improves tire vulcanization quality, reduces energy consumption, and enhances production efficiency.

[0171] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0172] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0173] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0174] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0175] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0176] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0177] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

Claims

1. A rubber vulcanization method based on electric heating and temperature-pressure separation control, characterized in that, Includes the following steps: S1. Establish the upper mold temperature setting curve, lower mold temperature setting curve, and capsule pressure setting curve, and set the upper limit parameter for temperature difference, the upper limit parameter for vulcanization uniformity difference, and the mold closing time parameter. The upper limit parameter for temperature difference is used to limit the temperature difference between the upper mold and the lower mold, the upper limit parameter for vulcanization uniformity difference is used to limit the difference in vulcanization process between the upper and lower sides, and the mold closing time parameter is used to record the vulcanization process time. S2, the heat transfer medium is electrically heated by the heating tank, and the heat transfer medium is driven by the circulating motor to enter the upper mold circuit and the lower mold circuit respectively, so that the upper mold and the lower mold are independently heated and preheated to a steady state, and the actual temperature of the upper mold and the actual temperature of the lower mold are collected at the same time. S3. After the mold is closed, inert gas is injected into the capsule. The pressure inside the capsule is adjusted through a closed-loop pressure control valve to make it track the capsule pressure setting curve. The pressure is controlled in stages: low pressure for molding, pressure holding during vulcanization, and pressure relief and recovery. S4, during the vulcanization stage, the temperature closed loop only adjusts the electric heating power and the diversion flow rate to make the upper mold temperature and the lower mold temperature track the corresponding set curves respectively; the pressure closed loop only adjusts the pressure control valve and does not change the temperature setting; the temperature difference between the upper and lower molds is determined based on the measured temperatures of the upper and lower molds, and the vulcanization index difference is obtained based on the temperatures of the representative temperature measurement points on the upper and lower sides. When the temperature difference between the upper and lower molds or the vulcanization index difference exceeds the limit, only the temperature setting or diversion flow rate on the side lagging behind the vulcanization process is compensated, and the capsule pressure setting curve remains unchanged. S5, after reaching the preset vulcanization endpoint, stop heating, depressurize and recover the inert gas to the storage tank through the recovery valve, and reuse it after drying and filtration. Vacuum the capsule to shrink it and open the mold to remove the tire.

2. The method according to claim 1, characterized in that, In step S1, the upper limit parameter of temperature difference is taken as 1℃ to 5℃; the upper limit parameter of temperature difference is the maximum difference between the measured temperature of the upper mold and the measured temperature of the lower mold allowed during the vulcanization process. And / or, in step S2, the heat transfer medium is one or more combinations of heat transfer oil, water and ethylene glycol solution, and the heating tank heats the heat transfer medium to the heat transfer medium outlet temperature range of 150°C to 210°C. And / or, in step S2, when the deviation between the measured temperature of the upper mold and the temperature setting curve of the upper mold, and the deviation between the measured temperature of the lower mold and the temperature setting curve of the lower mold both fall within the allowable deviation range of preheating, the process proceeds to tire assembly; wherein, the allowable deviation of preheating is the temperature deviation parameter used to determine whether the preheating of the upper mold and the lower mold has reached a stable state.

3. The method according to claim 1, characterized in that, In step S3, the inert gas is nitrogen. The measured pressure inside the capsule is adjusted by the pressure control valve so that the measured pressure inside the capsule tracks the capsule pressure setting curve and enters the vulcanization pressure window. The measured pressure inside the capsule is the gas pressure inside the capsule detected by the pressure sensor, and the vulcanization pressure window is the pressure range that ensures the tire carcass is molded and shaped and vulcanized under pressure. And / or, in step S3, the capsule pressure setting curve includes a shaping low-pressure section and a vulcanization high-pressure section. The shaping low-pressure section has a pressure of 0.04 MPa to 0.20 MPa and a duration of 5 to 30 seconds. The shaping low-pressure section is used to position the embryo, unfold it and expel residual air.

4. The method according to claim 1, characterized in that, In step S4, the temperature closed loop adjusts the electric heating power of the upper mold circuit, the electric heating power of the lower mold circuit, the flow rate of the heat transfer medium in the upper mold circuit, and the flow rate of the heat transfer medium in the lower mold circuit, respectively. The flow rates of the heat transfer medium in the upper mold circuit and the lower mold circuit are regulated by a frequency-controlled circulating motor and a flow-dividing proportional valve. And / or, in step S4, the temperatures of the representative temperature measuring points on the upper mold side and the lower mold side are collected. Based on the apparent activation energy, gas constant, reference absolute temperature, and temperature changes of each representative temperature measuring point during the vulcanization process of the corresponding rubber compound, the equivalent vulcanization index of the upper side and the equivalent vulcanization index of the lower side are obtained respectively, and the difference between the two is used to determine the vulcanization uniformity difference. The representative temperature measuring points are the temperature collection positions in the tire crown, tire shoulder, tire sidewall, or bottom of the lower tire sidewall used to characterize the vulcanization process.

5. The method according to claim 1, characterized in that, In step S5, when the equivalent vulcanization index of the slowest vulcanization point reaches the target equivalent vulcanization index, or the maximum vulcanization time is reached, heating is stopped and depressurization and recovery are initiated. The slowest vulcanization point is the tire part with the most delayed vulcanization process, the target equivalent vulcanization index is the index threshold for determining the completion of vulcanization, and the maximum vulcanization time is the maximum time allowed to perform vulcanization.

6. The method according to claim 1, characterized in that, A dryer and a filter are installed between the recovery valve and the gas storage tank to ensure that the dew point of the recovered inert gas is below -20°C; wherein, the dew point is the temperature at which the gas begins to condense under the current pressure; and, between step S2 and step S3, a capsule dehumidification step is performed, which includes at least one cycle of filling with inert gas and vacuuming to reduce the moisture content inside the capsule.

7. A rubber vulcanization system based on electric heating and temperature-pressure separation control, characterized in that, The system for implementing the method according to any one of claims 1 to 6, the system comprising: A vulcanizing machine, comprising a mold and a capsule, the capsule being used to apply internal pressure to the tire carcass; A heating tank, comprising an electric heating element, for heating a heat transfer medium; A circulating motor is connected to the upper mold circuit and lower mold circuit of the heating tank and the mold, and is used to drive the heat transfer medium to circulate. Gas storage tank, used to store inert gases; The pressure control valve and pressure sensor are installed on the gas pipeline from the gas tank to the capsule to regulate and detect the actual pressure inside the capsule. A temperature sensor group, including at least a temperature sensor for detecting the temperature of the upper mold and the temperature of the lower mold; The controller is communicatively connected to the electric heating component, the circulating motor, the pressure control valve, the pressure sensor, and the temperature sensor group, respectively. The controller is configured to execute steps S1 to S5 to achieve decoupled control of the temperature closed loop and the pressure closed loop.

8. The system according to claim 7, characterized in that, The upper mold circuit and the lower mold circuit are respectively equipped with flow-dividing proportional valves to independently adjust the flow rate of the upper mold circuit and the flow rate of the lower mold circuit; the flow rate of the upper mold circuit is the flow rate of the heat transfer medium entering the upper mold circuit, and the flow rate of the lower mold circuit is the flow rate of the heat transfer medium entering the lower mold circuit. And / or, the system further includes a recovery pipeline and a recovery valve, the recovery pipeline connecting the capsule and the gas storage tank, and the recovery valve being used to control the inert gas discharged from the capsule during the depressurization phase to enter the filter, dryer and be recovered to the gas storage tank; And / or, the controller is configured to adjust the upper mold temperature setting curve, the lower mold temperature setting curve, the upper mold loop flow rate, or the lower mold loop flow rate online according to the vulcanization uniformity difference, so that the vulcanization uniformity difference does not exceed the upper limit parameter of the vulcanization uniformity difference; wherein, the vulcanization uniformity difference is the difference between the upper equivalent vulcanization index and the lower equivalent vulcanization index.

9. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1-6.

10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1-6.

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