A vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control

Abstract

The present invention provides a tire vulcanization process that uses a non-water-soluble shaping medium to achieve segmented pressure control. At the initial stage of pre-vulcanization, the interior of the bladder is filled with a non-water-soluble gas to shape the green tire, and then the heating medium inside the bladder is converted to superheated water. The superheated water pressure is increased from low pressure to high pressure for shaping in stages, and the internal pressure is gradually increased. After each stage of increasing the internal pressure, the pressure is maintained for a period of time. Finally, vulcanization is carried out under the circulation of superheated water. Its purpose is to prevent steam from turning into liquid water during the pre-vulcanization stage, avoid instantaneous large drops and rises in internal pressure, and prevent low-pressure steam from directly turning into high-pressure superheated water, resulting in large and rapid changes in internal pressure. This can reduce the risk of unevenness inside the tire, asymmetry on both sides of the crown center, and bent wires in 25-inch and above engineering radial tires after vulcanization.

Description

Technical Field

[0001] The present invention relates to the technical field of tire rubber, in particular to a vulcanization process for engineering radial tires with an area of ​​25 inches or more, which utilizes a non-water-soluble shaping medium to realize segmented pressure control. Background Art

[0002] The tire curing bladder acts as the inner mold of the tire mold. During the green tire curing process, it adheres to the tire's inner casing to achieve the desired curing and shaping function. During the pre-curing stage for conventional OTR tires larger than 25 inches, steam at a certain pressure is directly injected into the bladder, rapidly raising the internal pressure to a specified value. After preheating stops, the bladder is filled with superheated water at a higher pressure, rapidly increasing the internal pressure to a specified higher pressure, causing the bladder to expand and support the tire rubber. The superheated water is then circulated to maintain the internal pressure constant, curing the green tire. This presents two problems. First, during the initial pre-curing stage, steam liquefies into water. During the transition from the high-temperature steam of the preheating period to the superheated water at a lower temperature but higher pressure, the steam in the bladder transforms into liquid water, causing the internal pressure of the bladder to drop sharply momentarily before rapidly rising to the specified pressure. Consequently, the fluctuating pressure during the curing process can cause internal dents in the green tire, leading to unevenness and severe bending of the steel wires in the finished tire. The second issue is that when the bladder's internal pressure changes directly from low-pressure steam to higher-pressure superheated water, the internal pressure fluctuates significantly and rises rapidly. Subsequently, the bladder directly enters the positive vulcanization stage. For thick-gauge engineering radial tires, the green tire does not have sufficient time and buffering to set its shape. The massive stress generated by the rapid expansion of the bladder is released, resulting in unevenness inside the finished tire, asymmetry between the left and right sides of the tire, and severe bending of the steel wire. These two issues ultimately lead to a noticeable unevenness inside the vulcanized tire, asymmetry around the crown of the finished tire, and even more severe bending of the steel wire in the finished tire. Summary of the Invention

[0003] To address the aforementioned technical issues, the present invention provides a vulcanization process for OTR tires larger than 25 inches that utilizes a non-water-soluble sizing medium to achieve segmented pressure control. This process aims to prevent steam from converting into liquid water during the pre-vulcanization stage, thereby avoiding sudden and significant drops and increases in internal pressure. It also prevents low-pressure steam from directly converting into high-pressure superheated water, which would cause large and rapid changes in internal pressure. This reduces the risk of uneven interiors, asymmetric crown center, and bent wires in OTR tires larger than 25 inches after vulcanization.

[0004] The object of the present invention is achieved in the following manner:

[0005] A vulcanization process for engineering radial tires larger than 25 inches that utilizes a non-water-soluble shaping medium to achieve segmented pressure control. In the initial pre-vulcanization stage, a non-water-soluble gas is filled inside the bladder to shape the green tire. Then, the heating medium inside the bladder is switched to superheated water, and the superheated water pressure is increased from low pressure to high pressure to shape the tire in stages. The internal pressure is gradually increased, and the pressure is maintained for a period of time after each stage of internal pressure increase. Finally, vulcanization is performed while the superheated water circulates.

[0006] The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control specifically comprises the following steps:

[0007] Pre-vulcanization stage

[0008] (1) A low-pressure non-water-soluble gas is introduced into the vulcanization capsule until the pressure inside the vulcanization capsule reaches the pressure of the low-pressure non-water-soluble gas and the pressure is maintained for a period of time;

[0009] (2) Stop passing the non-water-soluble gas, and pass superheated water with a higher pressure than the non-water-soluble gas into the vulcanizing bladder, while discharging the non-water-soluble gas. At this time, the superheated water pressure is P1, and the pressure inside the vulcanizing bladder reaches the superheated water pressure P1, and then the pressure is maintained for a period of time;

[0010] (3) Superheated water with a higher pressure than that in (2) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P2. The pressure inside the vulcanization bladder reaches the superheated water pressure P2 and the pressure is maintained for a period of time.

[0011] (4) Superheated water with a higher pressure than that in (3) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P3. The pressure inside the vulcanization bladder reaches the superheated water pressure P3 and the pressure is maintained for a period of time.

[0012] (5) Superheated water with a higher pressure than that in (4) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P4. The pressure inside the vulcanization bladder reaches the superheated water pressure P4 and the pressure is maintained for a period of time.

[0013] Vulcanization stage

[0014] (6) Superheated water with a higher pressure than that in (5) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P5. After the vulcanization bladder pressure reaches P5, vulcanization is carried out, and the pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water.

[0015] The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control specifically comprises the following steps:

[0016] Pre-vulcanization stage

[0017] (1) Introduce a low-pressure non-water-soluble gas with a pressure of 0.1-0.45 MPa into the vulcanizing bladder at a temperature of 15-30°C. Maintain the pressure for 3-20 minutes until the pressure inside the vulcanizing bladder reaches the pressure of the low-pressure non-water-soluble gas.

[0018] (2) Stop passing the non-water-soluble gas, and pass superheated water with a higher pressure than the non-water-soluble gas into the vulcanizing bladder, while discharging the non-water-soluble gas. The superheated water pressure P1 is 0.45-0.8 MPa, the temperature is 100-120 ° C, and the pressure in the vulcanizing bladder reaches the superheated water pressure P1. Maintain the pressure for 3-20 minutes.

[0019] (3) Superheated water with a higher pressure than that in (2) is introduced into the vulcanization bladder. The superheated water pressure P2 is 0.8-1.2 MPa and the temperature is 100-120°C. The pressure in the vulcanization bladder reaches the superheated water pressure P2 and the pressure is maintained for 3-20 minutes.

[0020] (4) Superheated water with a higher pressure than that in (3) is introduced into the vulcanization bladder. The superheated water pressure P3 is 1.3-2.0 MPa and the temperature is 100-120°C. The pressure inside the vulcanization bladder reaches the superheated water pressure P3 and the pressure is maintained for 3-20 minutes.

[0021] (5) Superheated water with a higher pressure than that in (4) is introduced into the vulcanization bladder. The superheated water pressure P4 is 2.0-3.0 MPa and the temperature is 100-120°C. The pressure in the vulcanization bladder reaches the superheated water pressure P4 and the pressure is maintained for 3-20 minutes.

[0022] Vulcanization stage

[0023] (6) Superheated water with a higher pressure than that in (5) is introduced into the vulcanization bladder. The superheated water pressure P5 is 3.0-5.0 MPa. After the pressure of the vulcanization bladder reaches P5, the pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water for 200-900 minutes. The temperature in the vulcanization bladder is the normal vulcanization temperature.

[0024] The water-insoluble gas is a non-flammable, non-explosive and non-reactive water-insoluble gas, that is, an inert water-insoluble gas.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] In the past, the pre-curing stage of engineering radial tires larger than 25 inches used steam to initially shape the green tire. The curing process of the engineering radial tire of the present invention breaks with this convention by filling the bladder with a non-water-soluble gas during the initial pre-curing stage to shape the green tire. This invention has the advantage that the non-water-soluble gas does not become liquid due to changes in the heating medium inside the bladder, thereby maintaining a stable internal pressure in the bladder, facilitating green tire shaping and preventing sudden and significant pressure drops and increases within the bladder. This prevents pressure fluctuations during the shaping process, which can lead to internal concavity in the green tire, unevenness in the finished tire, and severe bending of the steel wire. In the past, the internal pressure in the bladder of engineering radial tires larger than 25 inches was directly converted from low-pressure steam to high-pressure superheated water during the pre-curing stage. This resulted in large and rapid changes in internal pressure, leaving the green tire without sufficient time and buffering for formal shaping. Vulcanization then proceeded directly to the main curing stage, resulting in unevenness in the finished tire, asymmetry between the left and right sides of the tire, and severe bending of the steel wire. The vulcanization process of the engineering radial tire of the present invention is carried out in stages during the pre-vulcanization stage, where the internal pressure of the bladder is increased from low pressure to high pressure, as described in steps (1) to (6). The internal pressure is gradually increased, and after each stage of increasing the internal pressure, the pressure is maintained for a period of time, so that the green tire has sufficient time and a buffering process to be shaped, and the huge stress effect caused by the rapid expansion of the bladder is released, thereby helping to reduce the risk of unevenness inside the finished tire, asymmetry between the two sides of the crown center, and severe bending of the steel wire. The innovation of the present invention significantly alleviates the phenomena of unevenness inside the finished tire, asymmetry between the two sides of the crown center, and severe bending of the steel wire.

[0027] Some vulcanization processes use nitrogen for partial pressure shaping during the pre-vulcanization stage (for example, CN115674514A). These processes are primarily targeted at passenger car tires and are not suitable for OTR radial tires larger than 25 inches. The curing bladders used for OTR radial tires larger than 25 inches are several, even dozens or hundreds of times larger than those used for passenger car tires. Using nitrogen for partial pressure shaping throughout the pre-vulcanization stage takes a very long time, seriously impacting production efficiency. Furthermore, the use of nitrogen throughout the pre-vulcanization stage can cause bulging in the curing bladders used for OTR radial tires larger than 25 inches, significantly reducing the bladder's service life and increasing product costs.

[0028] Some vulcanization processes use superheated water throughout the pre-vulcanization phase (e.g., CN109501337A). This process is not suitable for OTR radial tires larger than 25 inches. The molds for OTR radial tires larger than 25 inches take a long time to fully close, and the superheated water is very hot. If the tire is shaped directly using superheated water, the tire interior will be prematurely heated before the molds are fully closed, causing rubber to flow and resulting in abnormal rubber distribution. This can lead to more severe thickness differences between the left and right shoulders of OTR radial tires larger than 25 inches, as well as more severe circumferential unevenness and wire bending in the shoulder area.

[0029] Taking into account the particularity of engineering radial tires larger than 25 inches, the present invention uses a water-insoluble gas first and then superheated water in the pre-vulcanization stage, thereby avoiding the problems existing in the above-mentioned pre-vulcanization stage using nitrogen or superheated water. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the internal pressure change of the bladder during the pre-vulcanization and curing stages of the present invention.

[0031] Figure 2 Schematic diagram of the changes in internal pressure of the bladder during the pre-vulcanization and curing stages of the conventional vulcanization process.

[0032] Figure 3 This is the internal condition of the finished tire after using the process of the present invention.

[0033] Figure 4 This shows the internal condition of the finished tire after using the conventional vulcanization process.

[0034] Figure 5 This is the bending condition of the finished tire steel wire after using the process of the present invention.

[0035] Figure 6 This shows the bending condition of the finished tire steel wire after using the conventional vulcanization process. DETAILED DESCRIPTION

[0036] A vulcanization process for engineering radial tires larger than 25 inches that utilizes a non-water-soluble shaping medium to achieve segmented pressure control. In the initial pre-vulcanization stage, a non-water-soluble gas is filled inside the bladder to shape the green tire. Then, the heating medium inside the bladder is switched to superheated water. The superheated water pressure is increased from low pressure to high pressure for shaping in stages, gradually increasing the internal pressure. After each stage of internal pressure increase, the pressure is maintained for a period of time. Finally, vulcanization is performed while the superheated water circulates.

[0037] The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control specifically comprises the following steps:

[0038] Pre-vulcanization stage

[0039] (1) A low-pressure non-water-soluble gas is introduced into the vulcanization capsule until the pressure inside the vulcanization capsule reaches the pressure of the low-pressure non-water-soluble gas and the pressure is maintained for a period of time;

[0040] (2) Stop passing the non-water-soluble gas, and pass superheated water with a higher pressure than the non-water-soluble gas into the vulcanizing bladder, while discharging the non-water-soluble gas. At this time, the superheated water pressure is P1, and the pressure inside the vulcanizing bladder reaches the superheated water pressure P1, and then the pressure is maintained for a period of time;

[0041] (3) Superheated water with a higher pressure than that in (2) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P2. The pressure inside the vulcanization bladder reaches the superheated water pressure P2 and the pressure is maintained for a period of time.

[0042] (4) Superheated water with a higher pressure than that in (3) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P3. The pressure inside the vulcanization bladder reaches the superheated water pressure P3 and the pressure is maintained for a period of time.

[0043] (5) Superheated water with a higher pressure than that in (4) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P4. The pressure inside the vulcanization bladder reaches the superheated water pressure P4 and the pressure is maintained for a period of time.

[0044] Vulcanization stage

[0045] (6) Superheated water with a higher pressure than that in (5) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P5. After the vulcanization bladder pressure reaches P5, vulcanization is carried out, and the pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water.

[0046] The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control specifically comprises the following steps:

[0047] Pre-vulcanization stage

[0048] (1) Introduce a low-pressure non-water-soluble gas with a pressure of 0.1-0.45 MPa into the vulcanizing bladder at a temperature of 15-30°C. Maintain the pressure for 3-20 minutes until the pressure inside the vulcanizing bladder reaches the pressure of the low-pressure non-water-soluble gas.

[0049] (2) Stop passing the non-water-soluble gas and pass superheated water with a higher pressure than the non-water-soluble gas into the vulcanization bladder. The superheated water pressure P1 is 0.45-0.8 MPa. Maintain the pressure for 3-20 minutes until the pressure in the vulcanization bladder reaches the superheated water pressure P1.

[0050] (3) Superheated water with a higher pressure than that in (2) is introduced into the vulcanization bladder. The superheated water pressure P2 is 0.8-1.2 MPa and the temperature is 100-120°C. The pressure in the vulcanization bladder reaches the superheated water pressure P2 and the pressure is maintained for 3-20 minutes.

[0051] (4) Superheated water with a higher pressure than that in (3) is introduced into the vulcanization bladder. The superheated water pressure P3 is 1.3-2.0 MPa and the temperature is 100-120°C. The pressure inside the vulcanization bladder reaches the superheated water pressure P3 and the pressure is maintained for 3-20 minutes.

[0052] (5) Superheated water with a higher pressure than that in (4) is introduced into the vulcanization bladder. The superheated water pressure P4 is 2.0-3.0 MPa and the temperature is 100-120°C. The pressure in the vulcanization bladder reaches the superheated water pressure P4 and the pressure is maintained for 3-20 minutes.

[0053] Vulcanization stage

[0054] (6) Superheated water with a higher pressure than that in (5) is introduced into the vulcanization bladder. The superheated water pressure P5 is 3.0-5.0 MPa. After the vulcanization bladder pressure reaches P5, vulcanization is carried out. The pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water. The vulcanization time is 200-900 minutes, and the temperature in the vulcanization bladder is the normal vulcanization temperature. At this time, the pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water during the vulcanization process, which is also called superheated water circulation.

[0055] The water-insoluble gas may be nitrogen, or other non-flammable, non-explosive, and non-reactive water-insoluble gases, that is, preferably an inert water-insoluble gas.

[0056] The schematic diagram of the change of the internal pressure of the bladder during the pre-vulcanization and curing stages of the present invention is as follows: Figure 1 As shown, the time for adding superheated water to pressurize the vulcanizing bladder in each stage of the present invention is very short, so the time for adding superheated water to pressurize the bladder is Figure 1 Not displayed in . Figure 2 Schematic diagram of the changes in internal pressure of the bladder during the pre-vulcanization and curing stages of the conventional vulcanization process. Figure 3 This is the internal condition of the finished tire after using the vulcanization process of the present invention. Figure 4 This is the internal condition of the finished tire after using the conventional vulcanization process; Figure 5 The bending condition of the finished tire steel wire after using the process of the present invention is shown in the figure. Figure 6 This shows the bending condition of the finished tire steel wire after using the conventional vulcanization process.

[0057] The present invention is described in detail below with reference to specific embodiments. It is necessary to point out that this embodiment is only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the contents of the present invention.

[0058] Example 1: 29.5R25 engineering radial tire

[0059] The tire vulcanization process using a non-water-soluble shaping medium to achieve segmented pressure control comprises the following steps:

[0060] Pre-vulcanization stage: introduce low-pressure nitrogen of 0.1MPa into the vulcanization bladder at a temperature of 20°C until the pressure inside the vulcanization bladder reaches 0.1MPa. The pressurization time is 2 minutes and the pressure is maintained for 3 minutes.

[0061] Superheated water with a higher pressure than nitrogen is introduced into the vulcanizing bladder. The superheated water pressure is 0.45 MPa and the temperature is 110°C. Nitrogen is discharged at the same time. That is, superheated water is introduced into the vulcanizing bladder while nitrogen is discharged until the pressure inside the vulcanizing bladder reaches 0.45 MPa. The superheated water pressurization time is 2 minutes, and then the pressure is maintained for 3 minutes.

[0062] Increase the superheated water pressure and introduce superheated water with a pressure of 0.8 MPa and a temperature of 105°C into the vulcanization bladder until the pressure inside the vulcanization bladder reaches 0.8 MPa. The pressurization time is 2.5 minutes, and then the pressure is maintained for 3 minutes.

[0063] Increase the superheated water pressure and introduce superheated water with a pressure of 1.3 MPa and a temperature of 105°C into the vulcanization bladder until the pressure inside the vulcanization bladder reaches 1.3 MPa. The pressurization time is 2.5 minutes, and then the pressure is maintained for 3 minutes.

[0064] Increase the superheated water pressure and introduce superheated water with a pressure of 2 MPa and a temperature of 105°C into the vulcanization bladder until the pressure inside the vulcanization bladder reaches 2 MPa. Pressurize for 2 minutes and then maintain the pressure for 3 minutes.

[0065] Vulcanization stage: Increase the superheated water pressure and introduce superheated water with a pressure of 3MPa and a temperature of 160°C into the vulcanization bladder. After the pressure of the vulcanization bladder reaches 3MPa, vulcanization is carried out. The pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water. The vulcanization time is 300min and the temperature in the vulcanization bladder is the normal vulcanization temperature.

[0066] Compared to conventional vulcanization, the internal pressure of the bladder remains stable during the pre-vulcanization phase and before and after changing the heating medium, with no sudden and significant drops or increases. This significantly reduces internal unevenness, asymmetry between the crown center, and severe wire bending in the finished tire.

[0067] Example 2: 27.00R49 engineering radial tire

[0068] The tire vulcanization process using a non-water-soluble shaping medium to achieve segmented pressure control comprises the following steps:

[0069] Pre-vulcanization stage: introduce nitrogen gas at a low pressure of 0.20 MPa into the vulcanization bladder at a temperature of 25°C until the pressure inside the vulcanization bladder reaches 0.2 MPa. The pressurization time is 2.5 minutes, and then the pressure is maintained for 10 minutes.

[0070] Superheated water with a higher pressure than nitrogen is introduced into the vulcanizing bladder. The superheated water pressure is 0.6 MPa and the temperature is 110°C. Nitrogen is discharged at the same time. That is, superheated water is introduced into the vulcanizing bladder while nitrogen is discharged until the pressure inside the vulcanizing bladder reaches 0.6 MPa. The pressurization time is 2.5 minutes, and then the pressure is maintained for 9 minutes.

[0071] Increase the superheated water pressure and introduce superheated water with a pressure of 0.9 MPa and a temperature of 110°C into the vulcanization bladder until the pressure inside the vulcanization bladder reaches 0.9 MPa. Pressurize for 3 minutes and then maintain the pressure for 8 minutes.

[0072] Increase the superheated water pressure and introduce superheated water with a pressure of 1.7 MPa and a temperature of 110°C into the vulcanization bladder until the pressure inside the vulcanization bladder reaches 1.7 MPa. The pressurization time is 3 minutes, and then the pressure is maintained for 15 minutes.

[0073] Increase the superheated water pressure and introduce superheated water with a pressure of 2.7 MPa and a temperature of 110°C into the vulcanization bladder until the pressure inside the vulcanization bladder reaches 2.7 MPa. The pressurization time is 3 minutes, and then the pressure is maintained for 15 minutes.

[0074] Vulcanization stage: Increase the superheated water pressure and introduce superheated water with a pressure of 3.6 MPa and a temperature of 160°C into the vulcanization bladder. After the pressure of the vulcanization bladder reaches 3.6 MPa, vulcanization is carried out. The pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water. The vulcanization time is 400 minutes, and the temperature in the vulcanization bladder is the normal vulcanization temperature.

[0075] Compared to conventional vulcanization, the internal pressure of the bladder remains stable during the pre-vulcanization phase and before and after changing the heating medium, with no sudden and significant drops or increases. This significantly reduces internal unevenness, asymmetry between the crown center, and severe wire bending in the finished tire.

[0076] Example 3: 40.00R57 engineering radial tire

[0077] The tire vulcanization process using a non-water-soluble shaping medium to achieve segmented pressure control comprises the following steps:

[0078] Pre-vulcanization stage: introduce low-pressure nitrogen of 0.45 MPa into the vulcanization bladder at a temperature of 30°C until the pressure inside the vulcanization bladder reaches 0.45 MPa. The pressurization time is 3.5 minutes, and then the pressure is maintained for 18 minutes.

[0079] Superheated water with a higher pressure than nitrogen is introduced into the vulcanizing bladder. The superheated water pressure is 0.8 MPa and the temperature is 120°C. Nitrogen is discharged at the same time. That is, superheated water is introduced into the vulcanizing bladder while nitrogen is discharged until the pressure inside the vulcanizing bladder reaches 0.8 MPa. The pressurization time is 3.5 minutes, and then the pressure is maintained for 20 minutes.

[0080] Increase the superheated water pressure and introduce superheated water with a pressure of 1.2 MPa into the vulcanizing bladder at a temperature of 120°C until the pressure inside the vulcanizing bladder reaches 1.2 MPa. Pressurize for 4 minutes and then maintain the pressure for 20 minutes.

[0081] Increase the superheated water pressure and introduce superheated water with a pressure of 2.0 MPa into the vulcanizing bladder at a temperature of 120°C until the pressure inside the vulcanizing bladder reaches 2.0 MPa. Pressurize for 4 minutes and then maintain the pressure for 18 minutes.

[0082] Increase the superheated water pressure and introduce superheated water with a pressure of 3.0 MPa into the vulcanizing bladder at a temperature of 120°C until the pressure inside the vulcanizing bladder reaches 3.0 MPa. Pressurize for 4 minutes and then maintain the pressure for 20 minutes.

[0083] Vulcanization stage: Increase the superheated water pressure and introduce superheated water with a pressure of 5 MPa and a temperature of 160°C into the vulcanization bladder. After the pressure of the vulcanization bladder reaches 5 MPa, vulcanization is carried out. The pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water. The vulcanization time is 800 minutes, and the temperature in the vulcanization bladder is the normal vulcanization temperature.

[0084] Compared to conventional vulcanization, the internal pressure of the bladder remains stable during the pre-vulcanization phase and before and after the heating medium is changed, with no sudden and significant drops or increases. This significantly reduces internal unevenness, left-right crown center asymmetry, and severe wire bending in the finished tire.

[0085] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. It should be pointed out that for those skilled in the art and any technician familiar with this technical field, without departing from the overall concept of the present invention, the technical solution and the inventive concept of the present invention are equivalently replaced or changed, and several changes and improvements are made, which should also be regarded as the scope of protection of the present invention.

Claims

1. A vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control, characterized in that: At the beginning of pre-vulcanization, the bladder is filled with non-water-soluble gas to shape the green tire. Then, superheated water with a higher pressure than the non-water-soluble gas is introduced into the vulcanization bladder, and the non-water-soluble gas is discharged at the same time, so that the heating medium inside the bladder is converted to superheated water. The superheated water pressure is increased from low pressure to high pressure for shaping in stages, and the internal pressure is gradually increased. After each stage of increasing the internal pressure, the pressure is maintained for a period of time. Finally, vulcanization is carried out under the circulation of superheated water.

2. The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control according to claim 1, characterized in that: The following steps are involved: Pre-vulcanization stage (1) A low-pressure non-water-soluble gas is introduced into the vulcanization capsule until the pressure inside the vulcanization capsule reaches the pressure of the low-pressure non-water-soluble gas and the pressure is maintained for a period of time; (2) Stop passing the non-water-soluble gas, and pass superheated water with a higher pressure than the non-water-soluble gas into the vulcanization bladder, while discharging the non-water-soluble gas. At this time, the superheated water pressure is P1, until the pressure in the vulcanization bladder reaches the superheated water pressure P1, and then maintain the pressure for a period of time; (3) Superheated water with a higher pressure than that in (2) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P2. The pressure inside the vulcanization bladder reaches the superheated water pressure P2, and then the pressure is maintained for a period of time. (4) Superheated water with a higher pressure than that in (3) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P3. The pressure inside the vulcanization bladder reaches the superheated water pressure P3, and then the pressure is maintained for a period of time. (5) Superheated water with a higher pressure than that in (4) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P4. The pressure inside the vulcanization bladder reaches the superheated water pressure P4, and then the pressure is maintained for a period of time. Vulcanization stage (6) Superheated water with a higher pressure than that in (5) is introduced into the vulcanization bladder. At this time, the superheated water pressure is P5. After the vulcanization bladder pressure reaches P5, vulcanization is carried out, and the pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water.

3. The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control according to claim 2, characterized in that: The following steps are involved: Pre-vulcanization stage (1) Introduce a low-pressure non-water-soluble gas with a pressure of 0.1-0.45 MPa into the vulcanizing bladder at a temperature of 15-30°C. Maintain the pressure for 3-20 minutes until the pressure inside the vulcanizing bladder reaches the pressure of the low-pressure non-water-soluble gas. (2) Stop passing the non-water-soluble gas and pass superheated water with a higher pressure than the non-water-soluble gas into the vulcanization bladder. The superheated water pressure P1 is 0.45-0.8 MPa and the temperature is 100-120°C. When the pressure in the vulcanization bladder reaches the superheated water pressure P1, maintain the pressure for 3-20 minutes. (3) Superheated water with a higher pressure than that in (2) is introduced into the vulcanization bladder. The superheated water pressure P2 is 0.8-1.2 MPa and the temperature is 100-120°C. The pressure in the vulcanization bladder reaches the superheated water pressure P2 and the pressure is maintained for 3-20 minutes. (4) Superheated water with a higher pressure than that in (3) is introduced into the vulcanization bladder. The superheated water pressure P3 is 1.3-2.0 MPa and the temperature is 100-120°C. The pressure inside the vulcanization bladder reaches the superheated water pressure P3 and the pressure is maintained for 3-20 minutes. (5) Superheated water with a higher pressure than that in (4) is introduced into the vulcanization bladder. The superheated water pressure P4 is 2.0-3.0 MPa and the temperature is 100-120°C. The pressure in the vulcanization bladder reaches the superheated water pressure P4 and the pressure is maintained for 3-20 minutes. Vulcanization stage (6) Superheated water with a higher pressure than that in (5) is introduced into the vulcanization bladder. The superheated water pressure P5 is 3.0-5.0 MPa. After the pressure of the vulcanization bladder reaches P5, vulcanization is carried out. The pressure and temperature in the vulcanization bladder are maintained by the flow of superheated water for 200-900 minutes.

4. The vulcanization process for engineering radial tires larger than 25 inches using a non-water-soluble shaping medium to achieve segmented pressure control according to claim 1, characterized in that: The water-insoluble gas is a non-flammable, non-explosive and non-reactive water-insoluble gas, that is, an inert water-insoluble gas.

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