A vulcanization method for load-carrying radial tire and tire

Abstract

The invention discloses a vulcanization method for a load-bearing radial tire and the tire, and relates to the field of tire manufacturing. The invention has a simple structure, and can control the vulcanization temperature and vulcanization time of the tire within a reasonable range by controlling the vulcanization temperature, vulcanization time and the ratio of the total thickness of the tire shoulder during the tire vulcanization production process, thereby ensuring that the rubber material fully flows during the tire vulcanization and the adhesion between the rubber material and the components, while reducing the heat generation and modulus of the rubber material, thereby reducing the rolling resistance of the tread and improving the durability.

Description

Technical Field

[0001] The invention relates to the field of tire manufacturing, in particular to a vulcanization method of a load-bearing radial tire and the tire. Background Art

[0002] The rolling resistance of a tire is affected by factors such as its rubber formula, profile structure, weight, and frame material properties. To reduce rolling resistance, all influencing factors must be considered comprehensively.

[0003] The manufacturing process of the load-carrying radial tire is mixing, preparation, extrusion, molding, and vulcanization. During the vulcanization process, the vulcanization temperature and time have a great influence on the performance of the tire. During the vulcanization process of the rubber compound, if the temperature is too high, the rubber compound will be over-mature, which will cause tire wear and reduce durability; if the temperature is too low, the rubber compound will not flow sufficiently and may cause poor adhesion of parts and thus reduce durability. Therefore, in the actual vulcanization production process, the vulcanization temperature must be kept reasonable. Summary of the invention

[0004] The object of the present invention is to provide a vulcanization method for a load-bearing radial tire, which solves the problems raised in the above-mentioned background technology by limiting the relationship between the vulcanization time and the total thickness of the tire shoulder.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for vulcanizing a load-bearing radial tire, the steps of the tire vulcanization method comprising:

[0007] The total shoulder thickness of the preset tire is G, and the total shoulder thickness G is the vertical distance from the end point of the tread to the inner side of the tire;

[0008] Entering the vulcanization step, checking the vulcanization conditions, including the vulcanization temperature F and the vulcanization time t, the vulcanization temperature F is 140° C. to 150° C., and the relationship between the vulcanization time t and the total thickness of the tire shoulder G is 1.10≤t / G≤1.36.

[0009] As a further solution of the present invention: the vulcanization time t is inversely proportional to the vulcanization temperature F, and the vulcanization time decreases by 2-3 minutes for every 5°C increase in the vulcanization temperature, and increases by 2-3 minutes for every 5°C decrease in the vulcanization temperature.

[0010] As a further solution of the present invention: the preparation step before entering the vulcanization step includes,

[0011] Preheating: preheat the machine, clean the mold cavity, fill with nitrogen, and check the vulcanization capsule;

[0012] Install the tire, check whether the curing bladder is in the contracted state, and the robot lifts the tire, moves it in, and descends to the tire installation height;

[0013] After shaping, fill with shaping pressure again, the upper ring descends, the manipulator closes and rises;

[0014] After the mold is closed and the robot is turned out, the mold is closed automatically. When the mold is closed to the pause height, the secondary molding valve automatically opens to fill the secondary molding pressure.

[0015] A tire, characterized in that it is made according to the vulcanization method described above.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the present invention has a novel structure, and can control the vulcanization temperature and vulcanization time of the tire within a reasonable range by controlling the vulcanization temperature, vulcanization time and the ratio of the total thickness of the tire shoulder during the vulcanization production process of the tire, thereby ensuring that the rubber material fully flows during the vulcanization of the tire and the adhesion between the rubber material and the components, while reducing the heat generation and modulus of the rubber material, thereby reducing the rolling resistance of the tread and improving the durability; in the actual vulcanization process, when the total thickness of the tire shoulder is preset to remain unchanged, by controlling the relationship between the vulcanization temperature and the vulcanization time, the stability of the tire performance can be effectively maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the axial cross-section structure of a load-bearing radial tire;

[0018] In the figure: 1-tread, 2-sidewall, 3-bead, 4-carcass, 5-belt, 6-groove, 7-shoulder pad. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the embodiment of the present invention, the finished tire is a tire blank before vulcanization, and the steps of vulcanization of the tire blank include: machine preheating → tire grabbing → tire loading → shaping → mold closing → vulcanization → mold opening → tire unloading, specifically:

[0021] S1. The total shoulder thickness of the tire is preset to be G, where the total shoulder thickness G is the vertical distance from the top of the shoulder to the inner side of the tire;

[0022] S2, preheating, preheat the machine, clean the mold cavity, fill with nitrogen, and check the vulcanization capsule;

[0023] S3, install the tire, check whether the vulcanizing bladder is in a contracted state, and the manipulator lifts the tire, transfers it, and descends to the tire installation height;

[0024] S4, shaping, then filling with shaping pressure, the upper ring descends, the manipulator closes, and rises;

[0025] S5, mold closing, after the robot turns out, the mold is automatically closed, and when the mold is closed to the pause height, the secondary molding valve automatically opens to fill the secondary molding pressure;

[0026] S6, vulcanization, after the mold is closed, enter the vulcanization step. Check the vulcanization conditions, including vulcanization temperature, vulcanization time and vulcanization pressure. This process is closely related to temperature, time and pressure. The rubber material undergoes a complex chemical reaction with the vulcanizer under a certain temperature, time and pressure, and the macromolecules with linear structures are cross-linked to form macromolecules with spatial three-dimensional network structures, so that the rubber products obtain the required physical and mechanical properties;

[0027] S7, mold opening and tire unloading, finished product trimming and appearance inspection.

[0028] Tire vulcanization time, vulcanization temperature and tire thickness, rubber thermal conductivity, rubber type, etc. interact with each other. This patent aims to provide a vulcanization method for the tire vulcanization process in the above step S6 regarding vulcanization temperature, time, and product thickness. The vulcanization temperature is the temperature of the outer surface of the tire during vulcanization, and the vulcanization time is the time from the start of vulcanization to the stop of vulcanization and mold opening. The vulcanization temperature F ranges from 140°C to 150°C, and the vulcanization time is t. The relationship between the vulcanization time and the total shoulder thickness G in S1 is 1.10≤t / G≤1.36.

[0029] The vulcanization time and the vulcanization temperature restrict each other. Through the above steps, the vulcanization temperature, vulcanization time and the total thickness of the tire shoulder can be limited during the vulcanization process of the tire, which can ensure that the rubber material flows fully during the vulcanization of the tire. While ensuring the adhesion between the components, the heat generation and modulus of the rubber material can be improved to reduce the rolling resistance of the tread. Because the vulcanization of the rubber material is a process of macromolecular cross-linking, as the vulcanization temperature increases or the vulcanization time is extended, the degree of oversulfurization of the rubber material is easy to deepen. Especially for load-bearing radial tires, the number of natural rubber parts used is relatively high. Compared with synthetic rubber, the vulcanization reaction of natural rubber is relatively large. During oversulfurization, the cross-linking bonds of the rubber material will undergo unfavorable processes and structures such as breaking, rearrangement, and cyclization, thereby reducing the modulus of the rubber material, increasing the delayed heat generation, and causing the durability and rolling resistance to decrease. Appropriate vulcanization conditions can reduce the distance between macromolecular chains and increase the cross-linking density, thereby increasing the 300% tensile stress, increasing the tensile strength and reducing the elongation at break, resulting in an increase in the modulus of the rubber material and a reduction in the delayed heat generation.

[0030] In order to verify the particularity of the tire vulcanization temperature range and the relationship between the tire vulcanization time and the shoulder total thickness ratio in the above step S6, the present invention makes the following experimental verification (see Table 1):

[0031]

[0032]

[0033] Table 1

[0034] The rolling resistance and durability of the conventional example 1 in Table 1 are expressed as an index of 100, and the larger the value, the better the rolling resistance and durability. It can be seen from the experimental data in Table 1 that:

[0035] 1. Compared with traditional example 1, the vulcanization time of examples 1-1, 1-2, and 1-3 remains unchanged, the vulcanization temperature within a specific range is reduced, and the rolling resistance and durability index are improved, but the lower the temperature, the smaller the effect on rolling resistance and durability. Referring to traditional example 1, example 1-1, and example 1-2, as the vulcanization temperature decreases, the rolling resistance and durability index increase; referring to example 1-2, example 1-3, and comparative example 1-1, as the temperature gradually decreases, the rolling resistance index and durability index decrease, among which the vulcanization temperature of comparative example 1-1 exceeds the specific range, and its rolling resistance and durability index are equivalent to those of traditional example 1.

[0036] 2. Relative to Comparative Example 1-2, the vulcanization temperature of Examples 1-4, 1-5, and 1-6 remains unchanged, the t / G ratio within a specific range decreases, and the rolling resistance and durability index increase. However, it should also be noted that the smaller the t / G ratio, the smaller the effect on rolling resistance and durability performance, or even a negative effect. Referring to Comparative Example 1-2, Examples 1-4, and 1-5, the rolling resistance and durability index increase with the decrease in the t / G ratio; referring to Examples 1-5, 1-6, and Comparative Example 1-3, as the t / G ratio gradually decreases, the rolling resistance index and durability index decrease. For Comparative Examples 1-2 and 1-3 where t / G exceeds a specific range, their rolling resistance and durability index are lower than or equivalent to those of Traditional Example 1.

[0037] In order to further verify the particularity of the tire vulcanization temperature limit range and the ratio range of the tire vulcanization time to the total thickness of the shoulder in the above step S6, the present invention makes the following experimental verification (see Table 2):

[0038]

[0039] Table 2

[0040] The rolling resistance and durability of the conventional example 2 in Table 2 are expressed as an index of 100, and the larger the value, the better the rolling resistance and durability. It can be seen from the experimental data results in Table 2 that:

[0041] 1. When the vulcanization temperature is within the range of 140℃~150℃ and t / G is within the range of 1.10~1.35, the rolling resistance and durability are improved compared with the conventional example 1 and the comparative example 1. This is because the reduction of the vulcanization temperature and the reduction of the vulcanization time prevent the over-vulcanization of the rubber compound, and the cross-linking bonds will not break or rearrange. Under this condition, the 300% modulus and tensile strength are effectively increased, and the elongation at break is reduced, which leads to an increase in the modulus of the rubber compound and a reduction in hysteresis heat generation, thereby improving the rolling resistance and durability.

[0042] 2. When the vulcanization temperature is within the range of 140℃~150℃ and t / G is within the range of 1.10~1.35, the rolling resistance and durability are improved. When the vulcanization temperature and t / G ratio are outside the above-mentioned limited range, the rolling resistance and durability are reduced. Specifically: when the vulcanization temperature is greater than 150℃ and t / G>1.35, the rubber vulcanization is over-mature, which will cause tire wear and reduced durability; when the vulcanization temperature is less than 140℃ and t / G<1.1, the rubber flow is insufficient and may cause poor adhesion of components, thereby reducing durability and even affecting tire safety performance.

[0043] The vulcanization temperature is F, the vulcanization time is t, the vulcanization time t is inversely proportional to the vulcanization temperature F, the vulcanization time decreases by 2-3 minutes for every 5°C increase in the vulcanization temperature, and increases by 2-3 minutes for every 5°C decrease in the vulcanization temperature. Under this relationship, the tire rolling resistance durability performance does not change significantly, and the stability of the tire performance can be maintained. In order to verify the inverse proportional relationship between the vulcanization temperature and the vulcanization time, the present invention makes the following experimental verification (see Table 3):

[0044] Examples 1-3 Example 3-1 Example 3-2 Vulcanization temperature (℃) 140 145 150 Vulcanization time t(min) 50 48 46 Total thickness of tire shoulder G(mm) 40 40 40 t(min) / G(mm) 1.25 1.2 1.15 Rolling resistance index 102 102 101.9 Durability Index 103 103.1 103

[0045] Table 3

[0046] Table 3 uses Examples 1-3 in Table 1 as a reference, and adds Examples 3-1 and 3-2 to verify the relationship between vulcanization temperature and vulcanization time. The larger the index, the better the rolling resistance and durability. It can be seen from the experimental data results in Table 3:

[0047] When the vulcanization temperature is within the range of 140℃~150℃, t / G is within the range of 1.10~1.35 and the total thickness G of the tire shoulder remains unchanged, the vulcanization time is reduced by 2min for every 5℃ increase in the vulcanization temperature, which can maintain the rolling resistance index and durability of the tire at a relatively stable value, thereby further maintaining the stability of the tire performance.

[0048] The present invention has a novel structure and stable operation. When in use, the present invention can control the vulcanization temperature and vulcanization time of the tire within a reasonable range by controlling the vulcanization temperature, vulcanization time and the ratio of the total thickness of the tire shoulder during the tire vulcanization production process, thereby ensuring that the rubber material fully flows during tire vulcanization and the adhesion between the rubber material and the components can be reduced while reducing the heat generation and modulus of the rubber material, thereby reducing the rolling resistance of the tread and improving the durability.

[0049] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for vulcanizing a load-bearing radial tire, characterized in that: The steps of the tire vulcanization method include: The total shoulder thickness of the tire is preset to be G, and the total shoulder thickness G is the vertical distance from the top of the shoulder to the inner side of the tire; Entering the vulcanization step, checking the vulcanization conditions, including the vulcanization temperature F and the vulcanization time t, the vulcanization temperature F is 140° C. to 150° C., and the relationship between the vulcanization time t and the total thickness of the tire shoulder G is 1.10≤t / G≤1.

36.

2. A method for vulcanizing a load-bearing radial tire according to claim 1, characterized in that: The vulcanization time t is inversely proportional to the vulcanization temperature F. For every 5°C increase in the vulcanization temperature, the vulcanization time decreases by 2-3 minutes. For every 5°C decrease in the vulcanization temperature, the vulcanization time increases by 2-3 minutes.

3. The method for vulcanizing a load-bearing radial tire according to claim 1, characterized in that: The preparation steps before entering the vulcanization step include: Preheating: preheat the machine, clean the mold cavity, fill with nitrogen, and check the vulcanization capsule; Install the tire, check whether the airbag is in the contracted state, the robot lifts the tire, moves in, and descends to the tire installation height; After shaping, fill with shaping pressure again, the upper ring descends, the manipulator closes and rises; After the mold is closed and the robot is turned out, the mold is closed automatically. When the mold is closed to the pause height, the secondary molding valve automatically opens to fill the secondary molding pressure.

4. A tire, characterized in that: Prepared according to any one of claims 1 to 3.

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