A method and apparatus for testing the durability of a tire

Abstract

This disclosure relates to the field of tire testing technology, and proposes a test method and apparatus for simulating tire durability performance. The method includes: determining the position of the steel cord embedded in the rubber according to the structure and material of the tire to be tested, obtaining a rubber sample with the steel cord; vulcanizing the rubber sample with the embedded steel cord to form a test specimen of a predetermined shape and size; subjecting the test specimen to reciprocating tension at a predetermined initial length and a predetermined tensile length under a predetermined constant temperature until cracks or fractures occur in the rubber; and estimating the durability performance of the tire to be tested based on the number of tensile cycles and stress corresponding to the occurrence of cracks or fractures. This disclosure simulates the actual usage of rubber and steel cord, effectively evaluating the fatigue performance of rubber under different rubbers with the same steel cord and different steel cords with the same rubber, allowing for early assessment of tire durability performance and reducing testing costs.

Description

Technical Field

[0001] This disclosure relates to the technical field of tire testing, specifically to a testing method and apparatus for simulating tire durability performance. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] The tire carcass, as the main load-bearing component of a radial tire, is primarily composed of materials such as nylon, polyester, fiber, and steel cord. It largely determines the tire's shape under inflation and the initial stress in various parts. For heavy-duty radial truck tires, both the belt ply and the carcass use steel cord as their carcass material. Steel cord is one of the main components determining the tire's load-bearing capacity and a key factor affecting its durability.

[0004] Currently, domestic research on tire durability performance mainly falls into two categories: one is indoor testing using a tire durability drum testing machine, which results in a long production cycle and high cost for finished tires; the other is simulation testing using finite element analysis, which requires prior establishment of parameters such as rubber and steel cord information. Finite element simulation tests are highly dependent on parameters and require the formation of a comprehensive database. The accuracy of simulation test results differs somewhat from that of indoor test results, and the results are not entirely accurate. Summary of the Invention

[0005] To address the aforementioned problems, this disclosure proposes a test method and apparatus for simulating tire durability performance, which enables the evaluation of tire durability performance during the initial stage of tire design, specifically the testing of rubber and steel cord materials.

[0006] To achieve the above objectives, the present disclosure adopts the following technical solution:

[0007] One or more embodiments provide a test method for simulating tire durability performance, including the following steps:

[0008] Based on the structure and materials of the tire to be tested, the position of the steel cord embedded in the rubber is determined, and a rubber sample with steel cord is obtained.

[0009] The rubber sample embedded with steel cord is vulcanized and then made into a test specimen of a set shape and size.

[0010] At a set constant temperature, the initial length of the test specimen is set, and the test specimen is repeatedly stretched at a set tensile length until the rubber cracks or breaks.

[0011] The durability of the tire under test is estimated based on the number of tensile tests and stresses corresponding to the occurrence of cracks or fractures.

[0012] One or more embodiments provide a testing apparatus for simulating tire durability performance, comprising:

[0013] The test specimen vulcanization device is used to vulcanize the rubber sample in the vulcanization mold according to the set process standards to obtain a rubber sample with steel cords.

[0014] A cutting device is used to cut vulcanized rubber samples to obtain test specimens of a set shape and size;

[0015] A tensile testing machine is used to perform tensile tests on test specimens under set tensile conditions.

[0016] The data processor is used to estimate the durability of the tire under test based on the number of tensile tests and stresses corresponding to the occurrence of cracks or fractures obtained from tensile tests.

[0017] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0018] Based on the actual tire structure, this disclosure simulates the actual use of rubber and steel cord, which can effectively evaluate the rubber fatigue performance under different rubbers with the same steel cord and the same rubber with different steel cords. It can evaluate the tire durability performance in advance, and the durability performance test does not require the waste of finished tires. Only a small amount of rubber and steel cord are needed to make samples to achieve the prediction of durability performance, which greatly reduces the testing cost.

[0019] The advantages of this disclosure, as well as its additional advantages, will be described in detail in the following specific embodiments. Attached Figure Description

[0020] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute a limitation thereof.

[0021] Figure 1 This is a flowchart of the test method of Embodiment 1 of this disclosure;

[0022] Figure 2 This is a schematic diagram of the structure of the cut test specimen of Embodiment 1 of this disclosure;

[0023] Figure 3(a) is a first schematic diagram of the change in tensile length during reciprocating uniform stretching in the tensile test of Embodiment 1 of this disclosure;

[0024] Figure 3(b) is a second schematic diagram of the change in tensile length during the tensile test of Embodiment 1 of this disclosure using reciprocating uniform tensile stretching;

[0025] Figure 4(a) is a first schematic diagram of the tensile length change in the tensile test of Embodiment 1 of this disclosure using reciprocating non-uniform tensile stretching;

[0026] Figure 4(b) is a second schematic diagram of the tensile length change in the tensile test of Embodiment 1 of this disclosure using reciprocating non-uniform tensile stretching;

[0027] Figure 5 This is the first embedding method of steel cord embedded in rubber in Embodiment 1 of this disclosure;

[0028] Figure 6 This is the second embedding method of steel cord embedded in rubber in Embodiment 1 of this disclosure;

[0029] Figure 7 This is the third embedding method of steel cord embedded in rubber in Embodiment 1 of this disclosure;

[0030] Figure 8 This is the fourth embedding method of steel cord embedded in rubber in Embodiment 1 of this disclosure;

[0031] Among them: 1. Rubber sample, 2. Steel cord. Detailed Implementation

[0032] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0034] It should be noted that the terminology used herein is for descriptive purposes only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features within those embodiments can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0035] Example 1

[0036] In one or more of the technical solutions disclosed in the embodiments, such as Figures 1 to 8 As shown, a test method for simulating tire durability performance includes the following steps:

[0037] Step 1: Based on the structure and material of the tire to be tested, determine the position where the steel cord 2 is embedded in the rubber to obtain a rubber sample 1 with steel cord;

[0038] Step 2: After vulcanizing the rubber sample 1 embedded in the steel cord 2, it is made into a test specimen of a set shape and size.

[0039] Step 3: At the set constant temperature, set the initial length of the test specimen, and perform reciprocating stretching on the test specimen with the set tensile length until the rubber cracks or breaks.

[0040] Step 4: Estimate the durability of the tire under test based on the number of tensile cycles and stress corresponding to the occurrence of cracks or fractures.

[0041] Based on the actual tire structure, this embodiment simulates the actual use of rubber and steel cord. It can effectively evaluate the rubber fatigue performance under different rubbers with the same steel cord and the same rubber with different steel cords, and evaluate the tire durability performance in advance. Moreover, the durability performance test does not require the waste of finished tires. Only a small amount of rubber and steel cord are needed to make samples to achieve the prediction of durability performance, which greatly reduces the testing cost.

[0042] In step 1, the vulcanization mold is first selected according to the structure and material of the tire to be tested. After determining the embedding position of the steel cord 2, the steel cord 2 is embedded in the corresponding position in the mold to obtain a sample with steel cord.

[0043] Optionally, the embedding method of the steel cord 2 can be determined according to the actual structure of the tire; the embedding methods include single or single row straight steel cord through type, single or single row straight steel cord semi-through type, multiple or multiple rows straight steel cord through type and multiple or multiple rows straight steel cord semi-through type.

[0044] Specifically, the single or single-row steel cord through-type refers to the rubber sample 1 having one (or one row) straight through-type steel cord 2 embedded in it, with the structure as follows: Figure 5 As shown;

[0045] A single or single-row semi-through steel cord type involves embedding one (or one row) straight semi-through steel cord 2 within the rubber sample 1. The structure can be as follows: Figure 6 As shown;

[0046] Multiple or multiple rows of straight steel cords are used in the through-type test specimen. Taking two as an example, this means that two (or two rows) of straight steel cords are embedded in the rubber sample 1. The test specimen structure can be as follows: Figure 7 As shown;

[0047] A semi-through type with multiple or multiple rows of straight steel cords, taking two as an example, means embedding two (or two rows) of straight semi-through steel cords 2 in the rubber sample 1. The structure of the test specimen can be as follows: Figure 8 As shown.

[0048] In step 2, the rubber sample 1 with steel cord 2 embedded is vulcanized according to normal process standards, and after vulcanization, it is made into test specimens by cutting.

[0049] Optionally, the vulcanization standard of the sample can be determined according to the rubber used, and different vulcanization conditions can be formulated according to different rubbers;

[0050] Optionally, the shape of the test specimen can be straight or dumbbell-shaped; the number of test specimens is at least 3.

[0051] The structural diagram of the dumbbell-shaped test specimen is as follows: Figure 2 As shown, the initial test length of the test specimen itself is L, where L1 = L2 = 0.5L.

[0052] A further technical solution involves preparing a test specimen in step 2. The interval between the preparation of the test specimen and the tensile test in step 3 is 16 hours to 30 days, i.e., the shortest interval is not less than 16 hours and the longest interval is not more than 30 days.

[0053] In step 3, the test specimen is subjected to reciprocating tension using a tensile testing machine at a constant temperature until the rubber cracks or breaks.

[0054] One method of tensile testing involves using the length of the test specimen in its free state as the test length and performing reciprocating tension.

[0055] Another way to perform a tensile test is to first stretch the specimen to a specified length, measure this length, and use this length as the test length, then perform reciprocating stretching.

[0056] In this embodiment, during the tensile test, the test specimen is first stretched to a specified length, which can actually simulate the prestress of the steel cord 2 and rubber after the tire is inflated, and is more in line with the actual use of the tire.

[0057] In some embodiments, the stretching process adopts uniform stretching, and the tensile force is changed as the length changes, so that the stretching length can be increased and then decreased in a sawtooth waveform during the stretching process, as shown in Figure 3(a) and Figure 3(b).

[0058] In other embodiments, the stretching process can be non-uniform stretching, so that the stretching length can increase and then decrease sequentially according to a non-linear waveform; the non-linear waveform can be wavy, sine wave, or cosine wave, wherein the wavy waveform stretching length waveform is shown in Figure 4(a) and Figure 4(b).

[0059] In step 4, the fatigue strength of the rubber or the tensile strength of the steel cord 2 is evaluated by measuring the stress at which the rubber is damaged and the tear length of the rubber, thereby further assessing the durability of the tire.

[0060] Under the same test conditions, the longer a tire can be driven, the better its durability. This embodiment estimates the durability of the tire under test by establishing the correlation between tire driving time and tensile test results, using the following specific method:

[0061] Step 41: Prepare finished tires under the same preparation conditions and prepare test specimens with the same structure according to steps 1 to 2;

[0062] Step 42: Conduct a durability test on the finished tire and record the time of tire damage;

[0063] Step 43: Perform a tensile test on the test specimen and record the number of tensile cycles and the corresponding stress at the point of fracture.

[0064] Step 44: Correspond the tensile test results at fracture to the damage time of the finished tire durability test to obtain the relationship between the tensile test results at tensile fracture and the tire durability time under the set tensile test conditions. The tensile test results must include at least the number of tensile cycles and the corresponding stress.

[0065] In this embodiment, after establishing the relationship between durability time and tensile cycles for the tire to be tested, the durability performance can be tested simply by preparing test specimens with the same structure, without the need to prepare finished tires for long-term durability testing, thus reducing the testing cost and shortening the testing time.

[0066] The tensile test results data are the measurement data that need to be collected during the tensile test, including: ① the number of cycles of stretching when the rubber cracks; ② the length of the crack measured in each subsequent cycle of stretching after the rubber cracks begin to crack, in order to determine the crack propagation rate; ③ the total number of cycles of stretching when fracture occurs; ④ the maximum stress recorded when fracture occurs.

[0067] The durability performance is determined based on the tensile test results and the correlation between tire driving time and tensile test results.

[0068] Further technical solutions include a method for comparing the durability performance of tire test specimens with different structures. Specifically, this involves comparing tires with different structures using the same steel cord but different rubbers, or tires with different structures using different steel cords but different rubbers. The number of tensile test cycles at which the rubber cracks or breaks is considered; a higher number of tensile cycles indicates better durability. This test method can be used to select tire structures with good durability.

[0069] Optionally, test specimens are made according to different tire structures, and the type of test specimen corresponds to the aforementioned embedding method of steel cord 2, such as... Figures 5 to 8As shown, including but not limited to: single or single row straight steel cord through type, single or single row straight steel cord semi-through type, multiple or multiple rows straight steel cord through type, and multiple or multiple rows straight steel cord semi-through type.

[0070] This embodiment uses tensile testing to detect the fatigue performance of tire rubber and establishes a correlation between tensile test results and durability performance, thus enabling early evaluation of tire durability performance. A single test can yield two test results for the tire, achieving low-cost durability performance testing.

[0071] Example 2

[0072] Based on Example 1, this example provides a testing device for simulating tire durability performance, comprising:

[0073] The test specimen vulcanization device is used to vulcanize the rubber sample 1 with steel cord 2 embedded in the vulcanization mold according to the set process standards, so as to obtain the rubber sample 1 with steel cord.

[0074] A cutting device is used to cut the vulcanized rubber sample 1 into test specimens of a set shape and size;

[0075] A tensile testing machine is used to perform tensile tests on test specimens under set tensile conditions.

[0076] The data processor is used to estimate the durability of the tire under test based on the number of tensile tests and stresses corresponding to the occurrence of cracks or fractures obtained from tensile tests.

[0077] Before conducting durability tests, the data processor establishes a correspondence between tire driving time and tensile test results, and correlates the fractured tensile test results to obtain the correspondence between the number of tensile fractures and the corresponding stress under the set tensile test conditions and tire durability time.

[0078] In this embodiment, after establishing the relationship between durability time and tensile cycles for the tire to be tested, the durability performance can be tested simply by preparing test specimens with the same structure, without the need to prepare finished tires for long-term driving time, thus reducing the cost of durability performance testing and shortening the testing time.

[0079] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

[0080] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A test method for simulating tire durability performance, characterized in that, Includes the following steps: Based on the structure and materials of the tire to be tested, the position of the steel cord embedded in the rubber is determined, and a rubber sample with steel cord is obtained. The embedding methods of steel cord include: single or single row straight steel cord through type, single or single row straight steel cord semi-through type, multiple or multiple rows straight steel cord through type, and multiple or multiple rows straight steel cord semi-through type. The rubber sample embedded with steel cord is vulcanized and then made into a test specimen of a set shape and size. At a set constant temperature, the initial length of the test specimen is set, and the test specimen is repeatedly stretched at a set tensile length until the rubber cracks or breaks. Among them, the length of the test specimen in its free state is used as the test length, and reciprocating tension is performed; or, the specimen is first stretched to a specified length, this specified length is measured, and this specified length is used as the test length, and reciprocating tension is performed. The durability of the tire under test is estimated based on the number of tensile tests and stresses corresponding to the occurrence of cracks or fractures. The estimation of the tire's durability performance includes establishing the correlation between tire driving time and tensile test results. The specific method is as follows: Finished tires and test specimens with the same structure were prepared under the same preparation conditions. Perform durability tests on the finished tires and record the time when the tires are damaged; Perform a tensile test on the test specimen and record the number of tensile cycles and the corresponding stress at the point of fracture. By correlating the tensile test results at fracture with the damage time of the finished tire durability test, the relationship between the number of tensile tests and the corresponding stress at tensile fracture under the set tensile test conditions and the tire durability time is obtained.

2. The test method for simulating tire durability performance as described in claim 1, characterized in that: The test specimens are in the shape of straight strips or dumbbells.

3. The test method for simulating tire durability performance as described in claim 1, characterized in that: The interval between the completion of test specimen preparation and the tensile test shall be no less than 16 hours and no more than 30 days.

4. The test method for simulating tire durability as described in claim 1, characterized in that: During the tensile test, uniform stretching is used so that the stretching length increases and then decreases sequentially in a sawtooth waveform.

5. The test method for simulating tire durability as described in claim 1, characterized in that: The stretching process employs non-uniform stretching, so that the stretching length increases and then decreases sequentially according to a non-linear waveform.

6. The test method for simulating tire durability as described in claim 1, characterized in that: It also includes a method for comparing the durability of tire test specimens with different structures. Specifically, it compares tires with different structures under the same steel cord and different structures under different steel cords, or tires with different structures under the same rubber. The number of tensile test cycles when the rubber cracks or breaks is higher, indicating better durability.

7. A testing device for simulating tire durability performance, characterized in that, A test method for simulating tire durability performance according to any one of claims 1-6, comprising: The test specimen vulcanization device is used to vulcanize the rubber sample in the vulcanization mold according to the set process standards to obtain a rubber sample with steel cords. A cutting device is used to cut vulcanized rubber samples to obtain test specimens of a set shape and size; A tensile testing machine is used to perform tensile tests on test specimens under set tensile conditions. The data processor is used to estimate the durability of the tire under test based on the number of tensile tests and stresses corresponding to the occurrence of cracks or fractures obtained from tensile tests.

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