Tire variable pressure vulcanization process and vulcanization system

Abstract

The application provides a tire variable-pressure vulcanization process, which comprises the following steps: sending compressed inert gas into a pressure storage tank and heating the inert gas in the pressure storage tank; loading a tire blank into a vulcanization machine and sending the inert gas in the pressure storage tank into a vulcanization capsule to shape and preheat the tire blank by the heated inert gas; first stage vulcanization: the vulcanization machine is closed, the pressure of the inert gas in the vulcanization capsule is controlled to be 0.08-0.10 MPa, the temperature is controlled to be 195-215 DEG C, and the duration is 10-20 s, so that the rubber and the vulcanization mold are contacted and preliminarily softened under low pressure; second stage vulcanization: the pressure of the inert gas in the vulcanization capsule is gradually increased to 1.8-3.0 MPa; third stage vulcanization: the maximum pressure of the second stage vulcanization is maintained until the vulcanization is completed. The tire variable-pressure vulcanization process can reduce vulcanization defects and improve the qualified rate of finished tires.

Description

Technical Field

[0001] The invention belongs to the technical field of tire vulcanization, and in particular relates to a tire variable pressure vulcanization process and a vulcanization system. Background Art

[0002] Currently, traditional tire vulcanization processes mostly use superheated water, steam, or nitrogen as the vulcanization medium. This method involves instantly introducing high-pressure steam or superheated water into the bladder after vulcanization begins to reach the required temperature and pressure. However, this traditional process not only wastes energy and causes a large temperature difference between the upper and lower molds, but also leads to the following tire defects:

[0003] 1) At the moment of mold closing, due to the different thicknesses of the various parts of the tire blank and the low molding pressure, when the rubber first contacts the mold, part of the rubber cannot fit tightly to the mold and cannot be completely transformed into a viscous flow state, and there is a gap between the rubber and the mold surface. At this time, the internal pressure of the bladder is instantly increased to make all the rubber stick to the mold. Because the unsoftened rubber has a certain Green strength, its fluidity is poor, and the air between the gaps is not easy to discharge. If there is no vent at this position or the rubber is thick, it is easy to cause appearance defects such as surface glue deficiency; however, improving the fluidity of the rubber will cause changes in the processing performance of the rubber, affecting the stability of the component extrusion process, and the adjustment cycle is long.

[0004] 2) Instantaneous application of excessive pressure will cause the cords inside the tire to tighten instantly, making it difficult to release the stress, and easily causing other defects such as thin cords and cracks.

[0005] In view of the above problems that the existing vulcanization process may cause to the quality of finished tires, it is currently necessary to improve the vulcanization process of tires in order to improve the quality of finished tires. Summary of the Invention

[0006] In view of the shortcomings of the related art, the present invention provides a tire variable pressure vulcanization process and a vulcanization system, which can reduce vulcanization defects and improve the qualified rate of tires.

[0007] One aspect of an embodiment of the present invention provides a tire variable pressure vulcanization process, comprising the following steps:

[0008] Vulcanization preparation: compress the inert gas and send it into the pressure storage tank, and heat the inert gas in the pressure storage tank;

[0009] Shaping and preheating: The tire blank is loaded into the vulcanizer, and the inert gas in the pressure storage tank is sent into the vulcanizing bladder. The heated inert gas is used to shape and preheat the tire blank.

[0010] First stage vulcanization: The vulcanizing machine is closed, and the pressure of the inert gas in the vulcanizing bladder is controlled to be 0.08-0.10 MPa, the temperature is 195-215°C, and the duration is 10-20 seconds, so that the rubber material contacts the vulcanizing mold under low pressure and softens initially;

[0011] Second stage vulcanization: gradually increase the pressure of the inert gas in the vulcanization bladder to 1.8-3.0 MPa;

[0012] The third stage of vulcanization: maintain the maximum pressure of the second stage of vulcanization until the end of vulcanization.

[0013] In some embodiments of the present invention, during the second stage vulcanization process, pressurization is performed in stages according to the rheological properties of the rubber material on the surface of the tire blank, specifically including:

[0014] First stage boost: When the torque reaches M L Before, slowly increase the pressure of the inert gas in the curing bladder to 0.3-0.4 MPa;

[0015] Second stage boost: in M L ~T C5 During the time period between the two, slowly increase the pressure of the inert gas in the curing bladder to 1.4-1.5 MPa;

[0016] The third stage of boost: at T C5 ~T 30 During the time period between the two, the pressure of the inert gas in the vulcanizing bladder is increased to 1.8-3.0 MPa.

[0017] In some embodiments of the present invention, during the vulcanization preparation process, the inert gas is collected and stored in a gas storage tank, and the inert gas in the gas storage tank is pressurized to 2.5-3.5 MPa by a compressor and then sent to a pressure storage tank.

[0018] In some embodiments of the present invention, during the vulcanization preparation process, the inert gas in the pressure storage tank is heated by a gas heater so that the temperature of the inert gas reaches 195-215°C, and during the subsequent vulcanization process, the temperature of the inert gas is controlled so that it is always maintained in the range of 195-215°C.

[0019] In some embodiments of the present invention, a circulation pump is used to maintain the circulation of the inert gas in the curing bladder and the pressure storage tank during the entire curing process.

[0020] In some embodiments of the present invention, during the shaping and preheating process, the heated inert gas is used to shape the embryo once and twice at a pressure of 0.07 MPa for the first shaping and 0.08 MPa for the second shaping, and is preliminarily preheated.

[0021] In some embodiments of the present invention, during the vulcanization process, the pressure of the inert gas in the vulcanization bladder is controlled by a pressure regulating valve so that the pressure of the inert gas in the vulcanization bladder meets the requirements.

[0022] In some embodiments of the present invention, during the vulcanization preparation process, the vulcanization mold is heated to a set temperature by electric heating.

[0023] In some embodiments of the present invention, after the third stage of vulcanization is completed, the inert gas is recovered into a gas storage tank for next use.

[0024] Another embodiment of the present invention provides a tire variable pressure vulcanization system for performing the tire variable pressure vulcanization process as described above, the tire variable pressure vulcanization system comprising:

[0025] Gas storage tanks, which are used to collect and store inert gases;

[0026] a compressor connected to the gas storage tank for pressurizing the inert gas;

[0027] A pressure storage tank, which is connected to the compressor and is used to store pressurized inert gas;

[0028] A gas heater connected to the pressure storage tank and used to heat the inert gas;

[0029] a pressure regulating valve connected to the gas heater and used to control the pressure of the inert gas;

[0030] A vulcanizing machine, connected to a pressure regulating valve, for vulcanizing the tire blank;

[0031] An electric heater connected to the vulcanizer for electrically heating the vulcanizing mold of the vulcanizer;

[0032] The gas circulation pump is connected to the vulcanizer and the gas heater and is used to circulate the vulcanizing bladder of the vulcanizer and the heated inert gas in the pressure storage tank.

[0033] Compared with the prior art, the advantages and positive effects of the present invention are:

[0034] (1) The variable pressure vulcanization process for tires provided by at least one embodiment of the present invention first uses a relatively small vulcanization pressure during the vulcanization process to allow the rubber on the outer surface of the tire to contact the heated vulcanization mold, so that the rubber is first softened, and then the vulcanization pressure is gradually increased to a maximum value. This can avoid various defects caused by the instantaneous high pressure reached in the existing vulcanization process, reduce problems such as bubbles and rubber shortages, and improve the quality of the finished tire.

[0035] (2) The tire variable pressure vulcanization process provided by at least one embodiment of the present invention combines the rheological properties of the rubber and performs pressurization in three stages during the vulcanization process, so that the rubber can flow better in the mold, ensuring the density of the vulcanization of each component, reducing the generation of waste products such as missing rubber, thin lines, and cracks, and greatly improving the product qualification rate.

[0036] (3) The tire variable pressure vulcanization system provided by at least one embodiment of the present invention can perform a tire variable pressure vulcanization process. During the entire vulcanization process, the temperature of the inert gas is maintained by a gas heater, the pressure of each vulcanization stage is controlled by a pressure regulating valve, and the circulation of the inert gas during the vulcanization process is maintained by a gas circulation pump, thereby achieving control of the inert gas variable pressure vulcanization process, avoiding the defects of the existing vulcanization process, and improving the tire qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 A flow chart of a tire variable pressure vulcanization process provided by an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of a rheological curve measured by a rotorless rheometer in an embodiment of the present invention;

[0040] Figure 3 This is a schematic structural diagram of a tire variable pressure vulcanization system provided by an embodiment of the present invention.

[0041] In the picture:

[0042] 1. Gas storage tank; 2. Compressor; 3. Pressure storage tank; 4. Gas heater; 5. Pressure regulating valve; 6. Vulcanizing machine; 7. Gas circulation pump; 8. Electric heater; 9. Temperature measuring device; 10. Vacuum pump. DETAILED DESCRIPTION

[0043] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0044] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments unless there is a conflict.

[0045] It is worth noting that although the accompanying drawings may show a specific order of method steps, the order of the steps may differ from the order depicted. In addition, two or more steps may be performed simultaneously or partially simultaneously. Such variations will depend on the software and hardware selected and the designer's choice. All such variations are within the scope of this disclosure.

[0046] On the one hand, an embodiment of the present invention provides a tire variable pressure vulcanization process, such as Figure 1 As shown, the following steps are included:

[0047] S1 vulcanization preparation: compress the inert gas and send it into the pressure storage tank, and heat the inert gas in the pressure storage tank;

[0048] S2 shaping and preheating: The tire blank is loaded into the vulcanizer, and the inert gas in the pressure storage tank is sent into the vulcanizing bladder. The heated inert gas is used to shape and preheat the tire blank.

[0049] S3 first stage vulcanization: the vulcanizing machine is closed, and the pressure of the inert gas in the vulcanizing bladder is controlled to be 0.08-0.10 MPa, the temperature is 195-215°C, and the duration is 10-20 seconds, so that the rubber material contacts the vulcanizing mold under low pressure and is initially softened;

[0050] S4 second stage vulcanization: gradually increase the pressure of the inert gas in the vulcanization bladder to 1.8 ~ 3.0Mpa;

[0051] S5 third stage vulcanization: maintain the maximum pressure of the second stage vulcanization until the end of vulcanization.

[0052] The tire variable pressure vulcanization process provided by the embodiment of the present invention uses heated inert gas as the vulcanization medium to provide the internal temperature and pressure of the vulcanization bladder. During the vulcanization process, a relatively low vulcanization pressure is first applied to allow the rubber on the outer surface of the tire blank to contact the heated vulcanization mold, thereby softening the rubber. The vulcanization pressure is then gradually increased to a maximum value. This can avoid various defects caused by the instantaneous high pressure in existing vulcanization processes, reduce problems such as bubbles and rubber deficiency, and improve the quality of the finished tire.

[0053] The rheological properties of rubber are usually expressed by the rheological curve, which is the curve showing the relationship between the shear stress and shear rate of the fluid. Figure 2 Schematic diagram of the rheological curve measured by the rotorless rheometer provided in the embodiment of the present application. L Represents minimum torque; M H Represents maximum torque; T C5 Represents the time from the time the rubber compound is added to the mold and heated to the time when the torque reaches M5, where M5 = M L +(M H -M L )×5%; T 10 The scorch time is also called the induction period, which refers to the time from the time the rubber material is heated when it is added to the mold to the time when the torque is M 10 The time corresponding to the time, where M 10 =M L +(M H -M L )×10%;T 30 It represents the time from when the rubber material is heated after being added to the mold to when the torque is M 30 The time corresponding to the time, where M 30 =M L +(M H -M L )×30%;T 90 It is the process positive vulcanization time, which refers to the time from when the rubber compound is added to the mold and heated to when the torque reaches M 90 The time corresponding to the time, where M 90 =M L +(M H -M L )×90%.

[0054] In some embodiments of the present application, Figure 1 As shown in the figure, during the second stage of vulcanization, the pressure is increased in stages according to the rheological properties of the rubber compound on the tire surface, including:

[0055] S401 first stage boost: when the torque reaches M L Before the curing, the pressure of the inert gas in the curing bladder is slowly increased to 0.3-0.4 MPa. At this time, although the rubber compound has not yet converted into a viscous flow state, it has a certain fluidity. The rubber compound is tightly adhered to the curing mold by a small pressure. This period of time is generally about 1 minute.

[0056] S402 second stage boost: in M L ~T C5 During the time period between M L ~T C5between 1.4-1.5 MPa, the air bubbles between the rubber and the mold can be quickly evacuated, at this time the rubber has low viscosity and good flowability, and can quickly fill the gaps left by the air evacuation, and the rubber has good interface compatibility due to its good flowability, which can reduce the occurrence of rubber defects; in this stage, if the pressure is too high, the rubber will flow out of the exhaust hole too much, resulting in long rubber hairs, which can easily cause broken hairs or block the pores, and if the pressure is too low, the rubber cannot be tightly attached to the mold, which is not conducive to air evacuation, and the vulcanization pressure in this stage is determined to be about 1.4-1.5 MPa through multiple tests and experience, and in this range, the rubber defects are the least and the length of the vulcanized rubber hairs is appropriate; M L ~T C5 The time period between T

[0057] S403 third stage pressure increase: in the time period between T C5 ~T 30 The pressure of the inert gas in the vulcanization capsule is increased to 1.8-3.0 MPa; at T C5 ~T 30 At this time, the rubber begins to crosslink and starts to show a transition to an elastomer, and increasing the pressure to 1.8-3.0 MPa in this stage can make the rubber and the parts combine more tightly, with a larger crosslinking density, improving product quality, and the time period is generally 1-2 min; specifically, different final pressures can be selected for different tire types in this stage, for example, AT tires (all-terrain tires) or MT tires (mud tires) with complex structures require a pressure of 2.4-3.0 MPa, and if the pressure is too low (e.g., less than 1.8 MPa), the parts will not combine tightly enough, which can eventually cause delamination and other problems in the use of the finished tire; for example, 185 / 65R15 PCR tires (passenger radial tires) can use a pressure of 2.0-2.4 MPa, and if the pressure is too high, it can cause the internal cords of the tire to stretch too much, causing exposed cords, cracks, or uneven tire defects.

[0058] The vulcanization process provided in the above embodiments, combined with the rheological properties of the rubber, divides the second stage vulcanization process into three stages for pressure increase, and in each stage, the appropriate pressure range is selected according to the flow state of the rubber in this stage, so that the rubber can flow better in the mold, ensuring better adhesion to the vulcanization mold during the pressure increase process, and the parts combine more tightly, effectively reducing the occurrence of defective products such as rubber defects, thin lines, and cracks from a mechanistic point of view, greatly improving the product qualification rate.

[0059] In some embodiments of the present application, during the vulcanization preparation process, the inert gas is collected and stored in a gas storage tank. The inert gas in the gas storage tank is pressurized to 2.5-3.5 MPa by a compressor and then sent to a pressure storage tank for standby use.

[0060] In some embodiments of the present application, during the vulcanization preparation process, the inert gas in the pressure storage tank is heated by a gas heater so that the temperature of the inert gas reaches 195-215°C, and in the subsequent vulcanization process, the temperature of the inert gas is controlled so that it is always maintained in the range of 195-215°C, that is, when the temperature of the inert gas in the vulcanization bladder reaches 215°C, heating is stopped, and when the temperature drops below 195°C, heating is resumed. Vulcanization temperature is one of the important parameters in the vulcanization process. If the vulcanization temperature is too low, the internal vulcanization degree of the tire will be insufficient, resulting in premature vulcanization. If the vulcanization temperature is too high, it will cause serious internal over-vulcanization, which will ultimately affect product quality. The specific vulcanization temperature can be determined by the following method: first, an external temperature suitable for rubber vulcanization is determined, and then the buried wire temperature measurement is performed by setting different internal tire temperatures. Finally, the internal temperature field distribution of the tire is measured and the vulcanization degree of the corresponding tire components is calculated, and finally the appropriate temperature is selected. The temperature range provided in this embodiment is applicable to the variable pressure vulcanization process provided in this application. In the actual vulcanization process, those skilled in the art can select any value within the range of 195 to 215°C according to the different types of specific rubber materials, for example, it can also be 200°C, 205°C, 210°C, etc.

[0061] In some embodiments of the present application, during the entire vulcanization process, a circulation pump is used to maintain the circulation of the inert gas in the vulcanization bladder and the pressure storage tank, and the electrically heated inert gas is used as the vulcanization medium to provide the internal temperature and pressure for the vulcanization bladder, so that the vulcanization pressure and vulcanization temperature are always maintained under the required conditions.

[0062] In some embodiments of the present application, during the shaping and preheating process, the heated inert gas is used to shape the embryo once and twice at a pressure of 0.07 MPa for the first shaping and 0.08 MPa for the second shaping, and is preliminarily preheated.

[0063] In some embodiments of the present application, during the vulcanization process, the pressure of the inert gas in the vulcanization bladder is controlled by a pressure regulating valve so that the pressure of the inert gas in the vulcanization bladder meets the requirements.

[0064] In some embodiments of the present application, during the vulcanization preparation process, the vulcanization mold is heated to a set temperature by electric heating.

[0065] In some embodiments of the present application, after the third stage of vulcanization is completed, the inert gas is recovered into a gas storage tank for next use.

[0066] Another aspect of the present application provides a tire variable pressure vulcanization system for performing the tire variable pressure vulcanization process as described in any one of the above items. Figure 3 As shown, the tire variable pressure vulcanization system includes:

[0067] A gas storage tank 1, which is used to collect and store inert gas;

[0068] A compressor 2 connected to the gas storage tank 1 for pressurizing the inert gas;

[0069] A pressure storage tank 3, which is connected to the compressor 2 and is used to store pressurized inert gas;

[0070] A gas heater 4, which is connected to the pressure storage tank 3 and is used to heat the inert gas;

[0071] a pressure regulating valve 5 connected to the gas heater 4 and used to control the pressure of the inert gas;

[0072] a vulcanizer 6 connected to the pressure regulating valve 5 for vulcanizing the tire blank;

[0073] A gas circulation pump 7 is connected to the vulcanizer 6 and the gas heater 4 to circulate the heated inert gas between the vulcanizing bladder of the vulcanizer 6 and the pressure storage tank 3;

[0074] The electric heater 8 is connected to the vulcanizer 6 and is used to electrically heat the vulcanizing mold of the vulcanizer 6 .

[0075] The tire variable pressure vulcanization system provided in the above embodiment can execute the tire variable pressure vulcanization process provided in the first aspect of the embodiment of the present application. During the entire vulcanization process, the temperature of the inert gas is maintained by a gas heater, the pressure of each vulcanization stage is controlled by a pressure regulating valve, and the circulation of the inert gas during the vulcanization process is maintained by a gas circulation pump, thereby realizing control of the inert gas variable pressure vulcanization process, avoiding the defects caused by the existing vulcanization process, and improving the tire qualification rate.

[0076] In some embodiments of the present application, the tire variable pressure vulcanization system further includes: a temperature measuring device 9 connected to the vulcanizer 6, for measuring the temperature of the vulcanizer 6; a vacuum extraction device 10 connected to the vulcanizer 6, for vacuuming the vulcanization bladder after vulcanization is completed to discharge the inert gas in the vulcanization bladder.

[0077] Example 1

[0078] Taking LT 235 / 75R15 as an example, nitrogen is selected as the inert gas, and the variable voltage electric heating method of this application is used for vulcanization. The specific steps are as follows:

[0079] (1) Maintain the temperature of the vulcanization mold between 176 and 180°C by electric heating;

[0080] (2) Collecting and storing nitrogen in a gas tank;

[0081] (3) The nitrogen in the gas storage tank is pressurized to 2.5-3.5 MPa by a compressor and then sent to the pressure storage tank;

[0082] (4) Pass the nitrogen in the pressure storage tank through the gas heater to make the gas temperature reach 195-215℃;

[0083] (5) Load the tire blank into the vulcanizer and use the pressure regulating valve to release the heated nitrogen at a pressure of 0.07 MPa for the first shaping and 0.08 MPa for the second shaping to perform the first and second shaping of the tire blank and preheat it;

[0084] (6) The vulcanizing machine is closed. After the mold is closed, the heated nitrogen in the pressure storage tank is sent into the capsule through the pressure reducing valve. The pressure of the nitrogen in the capsule is 0.08-0.10 MPa and the temperature is 195-215°C. The duration is 15 seconds, so that the rubber material contacts the mold under low pressure and softens initially.

[0085] (7) Using a pressure regulating valve to increase the internal pressure in three stages, the specific increase rate is as follows: in the first stage, the vulcanization internal pressure is slowly increased to 0.3-0.4 MPa within 1 minute; in the second stage, the vulcanization internal pressure is slowly increased to 1.4-1.5 MPa within 2 minutes; in the third stage, the vulcanization internal pressure is increased to 2.4-2.6 MPa within 2 minutes;

[0086] (8) After the lifting is completed, the pressure is maintained at 2.4~2.6Mpa for 12 minutes; during the entire vulcanization process, a circulating pump is used to keep the gas in the vulcanization bladder and the pressure storage tank circulating and continuously heating, so that the temperature of the gas in the vulcanization bladder is always maintained between 195~215℃; the internal pressure is controlled by a pressure regulating valve to ensure that the pressure meets the requirements

[0087] (9) Nitrogen recovery takes 0.5 to 0.6 minutes. The nitrogen in the vulcanizing capsule is recovered into the nitrogen recovery tank through the pipeline power station to achieve the energy-saving purpose of recycling and reuse;

[0088] (10) After the vulcanization bladder is vacuumed for 0.1 to 0.2 minutes, the mold is opened and the tire is taken out.

[0089] Yield rate comparison

[0090] 3,000 tires were produced using the variable voltage electric heating nitrogen vulcanization process of Example 1 of the present application, of which 111 tires were returned for repair, with a pass rate of 96.3%, and 45 tires were missing glue, with a missing glue rate of 1.5%.

[0091] Similarly, for LT235 / 75R15 specification tires, 3,000 tires were produced using the traditional steam / nitrogen vulcanization process, resulting in 270 returned tires with a pass rate of 91%, of which 141 were missing glue, with a missing glue rate of 4.7%.

[0092] Similarly, for LT235 / 75R15 specification tires, 3,000 tires were produced using a constant pressure electric heating nitrogen vulcanization process, resulting in 306 returned tires with a pass rate of 89.8%, of which 198 were missing glue, with a missing glue rate of 6.6%.

[0093] From the above, it can be seen that the variable pressure electric heating inert gas vulcanization process of Example 1 of the present application, compared with the existing traditional steam / nitrogen vulcanization process and the constant pressure electric heating nitrogen vulcanization process, has fewer returned products, fewer cases of glue deficiency, and a significantly improved product qualification rate.

[0094] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to preferred embodiments, persons skilled in the art should understand that the specific implementation methods of the present invention may still be modified or some technical features may be replaced by equivalents without departing from the spirit of the technical solutions of the present invention, and all of these should fall within the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A tire variable pressure vulcanization process, characterized in that: The following steps are involved: Vulcanization preparation: compress the inert gas and send it into the pressure storage tank, and heat the inert gas in the pressure storage tank; Shaping and preheating: The tire blank is loaded into the vulcanizer, and the inert gas in the pressure storage tank is sent into the vulcanizing bladder. The heated inert gas is used to shape and preheat the tire blank. First stage vulcanization: The vulcanizing machine is closed, and the pressure of the inert gas in the vulcanizing bladder is controlled to be 0.08~0.10 MPa, the temperature is 195~215℃, and the duration is 10~20 s, so that the rubber material contacts the vulcanizing mold under low pressure and softens initially; Second stage vulcanization: gradually increase the pressure of the inert gas in the vulcanization bladder to 1.8~3.0 MPa; The third stage of vulcanization: maintain the maximum pressure of the second stage of vulcanization until the end of vulcanization; In the second stage of vulcanization, the pressure is increased in stages according to the rheological properties of the rubber compound on the tire surface, including: First stage boost: When the torque reaches M L Before, slowly increase the pressure of the inert gas in the curing bladder to 0.3~0.4Mpa; L Represents the minimum torque in the rheological curve; Second stage boost: in M L ~T C5 During the time period between T and T, slowly increase the pressure of the inert gas in the curing bladder to 1.4~1.5 MPa; C5 Represents the time from the time the rubber compound is added to the mold and heated to the time when the torque reaches M5, where M5=M L +(M H -M L )×5%,M H Represents the maximum torque in the rheological curve; The third stage of boost: at T C5 ~T 30 During the time period between T and T, the pressure of the inert gas in the curing bladder is increased to 1.8~3.0 MPa; 30 It represents the time from when the rubber material is heated after being added to the mold to when the torque is M 30 The time corresponding to the time, where M 30 =M L +(M H -M L )×30%.

2. The tire variable pressure vulcanization process according to claim 1, characterized in that: During the vulcanization preparation process, the inert gas is collected and stored in a gas storage tank. The inert gas in the gas storage tank is pressurized to 2.5~3.5 MPa by a compressor and then sent to the pressure storage tank.

3. The tire variable pressure vulcanization process according to claim 1, characterized in that: During the vulcanization preparation process, the inert gas in the pressure storage tank is heated by a gas heater to a temperature of 195~215℃, and in the subsequent vulcanization process, the temperature of the inert gas is controlled to always be maintained in the range of 195~215℃.

4. The tire variable pressure vulcanization process according to claim 3, characterized in that: During the entire vulcanization process, a circulation pump is used to keep the inert gas in the vulcanization bladder and the pressure storage tank circulating.

5. The tire variable pressure vulcanization process according to claim 1, characterized in that: During the shaping and preheating process, the heated inert gas is used to shape the embryo once and twice at a pressure of 0.07 MPa for the first shaping and 0.08 MPa for the second shaping, and is preliminarily preheated.

6. The tire variable pressure vulcanization process according to claim 1, characterized in that: During the vulcanization process, the pressure of the inert gas in the vulcanization bladder is controlled by a pressure regulating valve to ensure that the pressure of the inert gas in the vulcanization bladder meets the requirements.

7. The tire variable pressure vulcanization process according to claim 1, characterized in that: During the vulcanization preparation process, the vulcanization mold is heated to the set temperature by electric heating.

8. The tire variable pressure vulcanization process according to claim 2, characterized in that: After the third stage of vulcanization is completed, the inert gas is recovered into the gas storage tank for next use.

9. The tire variable pressure vulcanization process according to any one of claims 1 to 8, characterized in that: The method is performed by a tire variable pressure vulcanization system, which comprises: Gas storage tanks, which are used to collect and store inert gases; a compressor connected to the gas storage tank for pressurizing the inert gas; A pressure storage tank, which is connected to the compressor and is used to store pressurized inert gas; A gas heater connected to the pressure storage tank and used to heat the inert gas; a pressure regulating valve connected to the gas heater and used to control the pressure of the inert gas; A vulcanizing machine, connected to a pressure regulating valve, for vulcanizing the tire blank; An electric heater connected to the vulcanizer for electrically heating the vulcanizing mold of the vulcanizer; The gas circulation pump is connected to the vulcanizer and the gas heater and is used to circulate the vulcanizing bladder of the vulcanizer and the heated inert gas in the pressure storage tank.

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