A method of designing a tire to improve tire unevenness

Abstract

The application relates to the technical field of tires and discloses a tire design method for improving unevenness in a tire inner part, which eliminates unreasonable distribution of rubber material and mismatching of sizes between the rubber material and a groove of a mold in a design stage by evaluating the required amount of material of the whole tire and a divided area, flowable characteristics of rubber material, unflowability of non-rubber material, and a characteristic requirement that the non-rubber material is not expected to be deformed by extrusion, reduces the number of trial production times of a product development sample, and further improves development efficiency, reduces development cost, and shortens a development cycle.

Description

Technical Field

[0001] This invention relates to the field of tire technology, and more specifically to a tire design method for improving uneven tire lining. Background Technology

[0002] Uneven tire inner surface is a common phenomenon in tire development, design, and production. During the development phase, prototype testing and inspection of the tire's appearance and cross-section can reveal whether unevenness exists. When unevenness is found, countermeasures are taken by adjusting the tire structure, material dimensions, the shape or size of semi-finished rubber components, installation positioning dimensions, and equipment tooling parameters. This typically requires trying multiple solutions to improve the problem. After product development is completed and mass production begins, although the unevenness may have been improved during development, it may not have been completely eliminated. In such cases, production must be halted, problematic products handled, and the remaining issues and solutions from the development phase reviewed to further address the unevenness issue.

[0003] Uneven tire inner surfaces negatively impact tires in the following ways: From a performance perspective, it can lead to: ① poor dynamic balance; ② reduced comfort; ③ increased rolling resistance; ④ decreased high-speed performance; ⑤ decreased grip; and ⑥ abnormal wear. From a cost-benefit perspective, improving uneven tire inner surfaces requires modifications and validation during tire development or production, increasing material costs and extending the development cycle. For uneven inner surfaces that appear after mass production, production halts are necessary, incurring not only material costs but also impacting sales and increasing production costs.

[0004] In the early stages of tire design, it is necessary to analyze the material requirements of each segment of the tire cross-section. This analysis, combined with the semi-finished product design and its conversion relationship with the finished product dimensions, aims to balance the total material quantity of the tire blank and the material quantity in each part. This avoids material shortages or localized redundancy, reduces undesirable material flow, and achieves a rational distribution of material across the tire cross-section, thereby eliminating tire inner unevenness caused by design flaws. This improves design accuracy, reduces development costs and shortens the cycle time, and lowers the risk of inner unevenness during the production stage.

[0005] The current technology has the following shortcomings:

[0006] Firstly, in the early stages of product design—specifically, the design of longitudinal and transverse grooves in the mold—tire performance and lifespan are the primary considerations for groove depth design. However, the groove depth design in different areas and directions is not taken into account as a contributing factor to unevenness in the tire lining. During the product construction design phase, the dimensions of semi-finished and finished products are calculated and converted, and the overall material requirements are considered in the semi-finished product design. Due to constraints on material flowability: ① the flowability of the rubber compound is limited by the dimensions of the tire blank, the mold size, and the complete contact process between the bladder and the tire; ② non-rubber components lack flowability. This results in some areas having more material than required, while other areas have less material. When both of these situations occur simultaneously, unevenness in the tire lining will manifest.

[0007] Secondly, when the aforementioned unevenness in the tire lining occurs, try increasing the amount of rubber material in the concave areas of the cross-section or decreasing the amount of rubber material in the convex areas, and re-produce and test samples; confirm the tire's appearance and cross-section condition; if the unevenness still exists, try adjusting the construction design or position settings, and try multiple solutions to attempt to improve the unevenness in the tire lining. This process increases the number of design modifications and trial verifications, and also increases material costs, labor costs, depreciation and amortization costs, and cycle costs. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a tire design method for improving tire inner unevenness. Through analysis and design in the early stages of design, the method analyzes the mold design and material requirements of each part during the tire design phase and applies it to the design of semi-finished products and tire blanks. This eliminates tire inner unevenness caused by design problems, thereby reducing trial production costs and cycles, as well as reducing material losses and downtime during the production phase.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A tire design method for improving uneven tire interiors includes:

[0011] I. Design of tire cord length:

[0012] When the local rubber volume M of the semi-finished rubber compound in the tire crown is greater than or equal to the actual required rubber volume m, the design length of the carcass cord between the two steel wire rings of the tire is taken as the reference length for the unevenness of the tire interior. The reference length is the length of the carcass cord of the tire cross section measured according to the simulated material distribution state.

[0013] When the local rubber amount M of the semi-finished rubber compound in the tire crown is less than the actual required rubber amount m, in case of unevenness in the tire, the design length of the carcass cord between the two steel wire rings of the tire is less than the reference length. The reference length is the length of the carcass cord of the tire cross section measured according to the simulated material distribution state.

[0014] II. Belt Drum Perimeter Design:

[0015] When the local rubber volume M of the semi-finished rubber compound in the tire crown is greater than or equal to the actual required rubber volume m, there is no need to change the design circumference of the tire drum to address unevenness in the tire interior.

[0016] When the local rubber material M of the semi-finished rubber compound in the tire crown is less than the actual required rubber amount m, the design length of the belt drum circumference needs to be reduced based on the original design to address the unevenness of the tire interior.

[0017] III. Rubber content design for localized areas of the tire crown:

[0018] The crown is divided into sections based on the tire mold dimensions; if the number of main grooves in the tire is n, then the crown is divided into n+1 sections.

[0019] A 3D simulation method is used to create a three-dimensional model of the tire. The volume of rubber in each section is taken as the rubber demand for each section. Based on the rubber demand for each section, the semi-finished tire tread is divided into sections, and the volume of rubber in each section is calculated. The volume of rubber in each section of the semi-finished tire tread is adjusted to be consistent with the rubber demand for the corresponding section; or the volume of rubber in each section of the semi-finished tire tread is made smaller than the rubber demand for the corresponding section.

[0020] IV. Tire structure and mold groove design:

[0021] The material structure design thickness h of the tire crown, the design thickness H of the convex peak, the total design thickness Tn of any point on the tire shoulder, and the rubber thickness TGn at the bottom of the groove must meet the following requirements:

[0022] h+H≤Tn-TGn.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] This invention provides a tire design method that assesses material requirements by evaluating the tire as a whole and by its individual regions, considering the flowability of rubber materials, the non-flowability of non-rubber materials, and the requirement that non-rubber materials should not be deformed under pressure. This method eliminates unreasonable allocation of rubber materials during the design phase and also eliminates dimensional mismatches between rubber materials and mold grooves. It reduces the number of prototype trials required for product development, thereby improving development efficiency, reducing development costs, and shortening the development cycle. Attached Figure Description

[0025] Figure 1 A schematic diagram of the tire cords;

[0026] Figure 2 This is a schematic diagram illustrating the unevenness of the tire interior in different sections of the crown.

[0027] Figure 3 This is a schematic diagram of the various sections of the semi-finished tire tread.

[0028] Figure 4 This is a schematic diagram of the tire's structural dimensions;

[0029] Figure 5 A schematic diagram of a tire with an uneven inner surface;

[0030] Figure 6 A schematic diagram of a tire cross-section with a flat inner surface;

[0031] Figure 7 This is a schematic diagram of tire forming.

[0032] Figure 8 This is a schematic diagram of the material used for the tire crown.

[0033] Figure 9 This is a schematic diagram of the tire blank pressing process. Detailed Implementation

[0034] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] 1. Unevenness in the tire crown occurs in the middle area, between the two main tread grooves, or in the tire shoulder area; it manifests as wavy belt layers or unevenness in the tire interior, as shown in Table 1.

[0036] Table 1

[0037] See Figure 5 See Figure 6

[0038] 2. The principle behind unevenness in the tire interior

[0039] 2.1 During the tire molding process, the tire carcass bulge surface is a smooth cylindrical side arc surface, and no external force is applied during the bonding process to cause unevenness in the rubber material at the tire carcass lines or sidewalls, resulting in an effect as follows: Figure 7 As shown.

[0040] 2.2 Similarly, the belt drum has a smooth arc surface, and the material bonding sequence is belt layer → crown layer → tread. During this process, there will be no unevenness or bumps in the bottom material, such as... Figure 8 As shown.

[0041] 2.3 Tire blank compression process: The tire inflation pressure is constant, the gas pressure at all points inside the tire blank is constant, and the external force applied to the tire blank surface is uniform. Compression is carried out at a constant speed, from the crown → sidewall → bead, i.e., T0 → T1 → T2 → T3 → T4 → T5. This will not cause permanent regional unevenness in the tire interior. Figure 9 As shown.

[0042] 2.4. Tire vulcanization stage:

[0043] 2.4.1 Differences exist in the contact process between different parts of the blank's outer surface and the mold: ① There is a time difference in the process of the outer surface of different parts of the blank making complete contact with the mold; ② The pressure and direction of the pressure on the blank vary depending on the depth of the grooves in the mold; ③ There is a pressure difference between the parts of the blank that have contacted the mold and the parts that have not contacted the mold; ④ There are differences in the material elongation in different areas.

[0044] 2.4.2 Differences also exist in the inner surface of the tire blank during the contact process with the capsule: ① There is a time difference in the process of the inner surface of different parts of the tire blank making complete contact with the outer surface of the capsule; ② There is a pressure difference between the parts of the tire blank that have been in contact with the capsule and the parts that have not been in contact with the capsule; ③ There are differences in the material elongation in different areas.

[0045] The above conditions during the vulcanization stage determine that the values ​​of belt circumference and tire body circumference will affect the occurrence of unevenness in the tire.

[0046] 2.5 At the same time, due to the influence of tire manufacturing equipment, processes, and vulcanizing bladder size, it is difficult for different parts of the tire blank to achieve synchronous stretching or equal pressure in different areas during the vulcanization process.

[0047] 3. Problem-solving measures

[0048] 3.1 Factors affecting tire unevenness: ① The length of the tire carcass line between the two steel wire rings determines the inner contour shape of the tire (cross-sectional direction); ② The circumference of the belt drum and the inner cavity of the mold determine the circumferential elongation of the tire carcass and belt layer; ③ Tire structure affects the amount of non-flowable material; ④ The amount of local rubber material affects the amount of flowable material; ⑤ The groove depth at different positions of the mold affects the flowability of the material.

[0049] 3.2 Overview of the influence and constraints of each factor, see Table 2.

[0050] Table 2

[0051]

[0052] 3.3 In view of the above, in order to avoid uneven tire lining, a comprehensive analysis and consideration should be carried out in the early stage of tire design, and the following requirements should be met from the design perspective to reduce the risk of uneven tire lining.

[0053] 3.3.1 Length of tire carcass cords between the two steel wire rings, see [reference]. Figure 1 The shaded area in the image.

[0054] The length of the tire carcass cord between the two steel wire rings is one of the direct determining factors of the tire's cross-sectional inner profile, and the suitability of its length affects the shape of the tire's cross-sectional inner profile.

[0055] During the process of the tire blank crown material stretching and contacting the inner surface of the mold, if the amount of rubber in a local area is insufficient, the impact of the tire carcass cord length between the two steel wire rings on tire inner unevenness can occur in two ways: ① If the tire carcass cord length is large, the tire carcass has a strong ability to stretch towards the inner diameter of the mold. In cases where the amount of rubber is insufficient in a local area, the tire carcass cord will locally bend and deform in the diameter direction to fill the gap. ② If the tire carcass cord length is small, the tire carcass cord has a weak ability to deform towards the inner diameter of the mold. This will drive the upper layer of rubber to flow in a more balanced distribution direction, reducing the impact of unsuitable rubber ratios on tire inner unevenness.

[0056] In view of the influence of tire cord length on tire unevenness mentioned above, the design requirements of this invention are as follows:

[0057] (1) When the local amount of rubber material in the crown is greater than or equal to the actual required amount of rubber material m, the cord length on the simulated cross section can be measured according to the material distribution of each part to address the unevenness of the tire.

[0058] (2) When the local rubber content M in the crown is less than the actual required rubber content m, the cord length needs to be reduced to address the unevenness in the tire interior. The reference length is the tire carcass cord length measured according to the simulated material distribution state to avoid unevenness in the tire interior. This situation often occurs when unevenness in the tire interior appears after the design of the semi-finished product, tooling, etc., is completed and the prototype is being tested, but the thickness of the finished rubber compound can be adjusted.

[0059] like Figure 2 As shown, section B is the section where unevenness occurs in the tire; Figure 3 It is a semi-finished product of tire tread rubber. Figure 3 The intervals a, b, and c in the intervals are respectively with Figure 2 The intervals A, B, and C in the diagram correspond to each other.

[0060] 3.3.2 Design of the belt drum perimeter

[0061] Due to tire performance requirements, tire molds are required to have grooves; in order to meet the requirements of the tire vulcanization mold for the characteristics of the green tire, the outer circumference of the green tire is designed to be smaller than the inner circumference of the mold; and the belt drum circumference design is to match the outer circumference of the green tire, meet the requirements of the belt layer angle of the finished tire, and achieve the tire's handling and comfort, etc., so the belt layer elongation coefficient is used as the main design parameter.

[0062] From a production complexity perspective, the angle of the semi-finished belt layer is usually fixed. The angle of the finished tire belt layer is achieved by adjusting the belt drum circumference, i.e., controlling the belt layer elongation coefficient, as well as the thickness of each material. The belt drum circumference and the inner mold dimensions determine the belt layer elongation coefficient; at the same time, the difference between the belt drum circumference and the inner mold cavity circumference affects the ease of material elongation and the flowability of the rubber compound.

[0063] During the process of the tire blank crown material stretching and contacting the inner surface of the mold, if the amount of rubber in a local area is insufficient, the impact of the belt drum circumference on tire inner surface unevenness can occur in two ways: ① If the belt drum circumference is designed to be large, the belt layer has a strong stretching capacity in the circumferential direction of the tire. In cases where the amount of rubber is insufficient in a local area, the belt layer will exhibit local bending deformation in the diameter direction, indicating insufficient filling rubber. ② If the belt drum circumference is designed to be small, the belt layer has a weak stretching capacity in the circumferential direction, which will drive the rubber material in its upper layer to flow in a more balanced distribution direction, reducing the impact of unsuitable rubber material ratio on tire inner surface unevenness.

[0064] In view of the above, in order to avoid the impact of belt bulge on tire unevenness, the design requirements are as follows:

[0065] ① When the local rubber volume M in the crown is greater than or equal to the actual required rubber volume m, no special requirements are needed for the design of the tire circumference to address unevenness in the tire interior.

[0066] ② When the amount of rubber material (M) in the crown area is less than the actual required amount, the belt drum circumference needs to be reduced to prevent unevenness in the tire lining. This situation often occurs when unevenness in the tire lining appears after the design of the semi-finished product or tooling has been completed and during the prototype trial production, but the thickness of the finished rubber material can be adjusted.

[0067] 3.3.3 Design of glue volume in local areas of the crown

[0068] The space between the mold grooves and the skeleton material is a closed area. When the blank and the mold surface are fully engaged, if there is a space where the outer surface of the blank and the inner surface of the mold are not fully in contact within the local closed area, the material in the adjacent area of ​​this area will be squeezed and flowed.

[0069] The tire crown area is divided into three sections: A, B, and C. Taking section B as an example, if the amount of rubber in a certain section is insufficient, when the tire blank surface in sections A and C is in complete contact with the inner surface of the mold, but section B is not in complete contact, a pressure difference occurs between the uncontacted and contacted areas. The two protrusions (main grooves) of the mold will continue to pressurize the lower layer of rubber and skeleton material, squeezing the rubber and skeleton material into section B, causing unevenness in the tire interior: sections A and C are flat, while section B is concave. Figure 2 .

[0070] To avoid the above problems, the following conditions must be met simultaneously during tire design:

[0071] The demand for rubber compounds in Region A is greater than or equal to the quantity of semi-finished rubber compounds (a) in Region A.

[0072] The demand for rubber compounds in Region B is greater than or equal to the quantity of semi-finished rubber compounds in Region B (b).

[0073] The demand for rubber compounds in Region C is greater than or equal to the quantity of semi-finished rubber compounds in Region C.

[0074] The optimal state is when the equality sign is true.

[0075] The implementation process of the above solution is as follows:

[0076] Step 1: When designing the tire tread, the crown is divided into sections based on the tire mold dimensions. When the number of main grooves is n, the crown is divided into n+1 sections.

[0077] The second step involves using 3D simulation to create a three-dimensional model, and then taking the rubber volume of each interval as the required rubber quantity for that interval. Based on the required rubber quantity for each interval, the semi-finished tire tread is divided into n+1 intervals, and the rubber volume for each interval is calculated. The rubber volume for each interval of the semi-finished tire tread is then adjusted to match the required rubber quantity for the corresponding interval obtained from the three-dimensional model.

[0078] A test tire was conducted according to the above plan, and no unevenness was found inside the tire.

[0079] 3.3.4 Tire structure and mold groove design

[0080] The carcass, belt layer, and crown belt layer in a tire structure are non-flowing materials that are not easily deformed after being bonded to the rubber compound. The mold grooves are rigid materials that impede the flow of the rubber compound during tire vulcanization, affecting the local material thickness.

[0081] If the amount of rubber in one or more closed sections is insufficient and cannot completely fill the closed section, while the amount of rubber in other adjacent areas is just enough but not excessive, structural material deformation will occur so that each closed section can be fully filled, resulting in unevenness in the tire.

[0082] When the thickness of the local material structure does not match the mold design, since both the mold protrusions and the structural material are non-flowable materials, there may be insufficient rubber material or the flow of rubber material may reduce the amount of rubber material at a certain position in the crown. As a result, the total thickness of the material in the local area exceeds that of the adjacent area, causing unevenness in the tire lining.

[0083] like Figure 4 As shown, to avoid the risk of unevenness in the tire interior caused by the tread groove design and tire structure design, the following conditions must be met between the crown material thickness h, the peak thickness H, the total thickness Tn at any point on the shoulder, and the bottom rubber thickness TGn:

[0084] h+H≤Tn-TGn.

[0085] The shoulder of the tire is located between the crown and the sidewall. The ridges are protrusions on the mold that correspond to the grooves on the tire.

[0086] It will be apparent to those skilled in the art that the present 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 its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0087] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A tire design method for improving uneven tire interior, comprising: I. Design of tire cord length: When the local rubber volume M of the semi-finished rubber compound in the tire crown is greater than or equal to the actual required rubber volume m, the design length of the carcass cord between the two steel wire rings of the tire is taken as the reference length for the unevenness of the tire interior. The reference length is the length of the carcass cord of the tire cross section measured according to the simulated material distribution state. When the local rubber amount M of the semi-finished rubber compound in the tire crown is less than the actual required rubber amount m, in case of unevenness in the tire, the design length of the carcass cord between the two steel wire rings of the tire is less than the reference length. The reference length is the length of the carcass cord of the tire cross section measured according to the simulated material distribution state. II. Belt Drum Perimeter Design: When the local rubber volume M of the semi-finished rubber compound in the tire crown is greater than or equal to the actual required rubber volume m, there is no need to change the design circumference of the tire drum to address unevenness in the tire interior. When the local rubber material M of the semi-finished rubber compound in the tire crown is less than the actual required rubber amount m, the design length of the belt drum circumference needs to be reduced based on the original design to address the unevenness of the tire interior. III. Rubber content design for localized areas of the tire crown: The crown is divided into sections based on the tire mold dimensions; if the number of main grooves in the tire is n, then the crown is divided into n+1 sections. A 3D simulation method is used to create a three-dimensional model of the tire. The volume of rubber in each section is taken as the rubber demand for each section. Based on the rubber demand for each section, the semi-finished tire tread is divided into sections, and the volume of rubber in each section is calculated. The volume of rubber in each section of the semi-finished tire tread is adjusted to be consistent with the rubber demand for the corresponding section; or the volume of rubber in each section of the semi-finished tire tread is made smaller than the rubber demand for the corresponding section. IV. Tire structure and mold groove design: The material structure design thickness h of the tire crown, the design thickness H of the convex peak, the total design thickness Tn of any point on the tire shoulder, and the rubber thickness TGn at the bottom of the groove satisfy the following: h+H≤Tn-TGn.

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