Test method for testing durability of HL tire bead

Abstract

The invention discloses a test method for testing the durability of an HL tire bead. The test method comprises the following steps: mounting a tire on a rim and inflating; the tire rim assembly is parked at the specified environment temperature; mounting the tire and rim assembly on a testing machine; the method comprises the following steps: selecting typical endurance test load and air pressure of an HL tire in combination with HL tire market use conditions, carrying out a static load test, obtaining deformation conditions of the tire under different test loads and air pressures through static load analysis, adjusting and determining test conditions, and setting an HL tire bead endurance test program; adjusting the test air pressure and starting the testing machine to automatically run until the tire is damaged and the machine is stopped or the program operation is finished; and checking the appearance of the tire, dismounting the tire and ending the test. According to the method, the fault of the tire bead part of the HL tire can be rapidly and accurately detected, and compared with an existing method, the method does not need to grind a tire tread and do not need to punch a test hole in the tire shoulder part of the tire, so that the test operation is simple, and the time and the cost are saved.

Description

Technical Field

[0001] The invention belongs to the technical field of tire bead durability evaluation and relates to a test method for testing the durability performance of a HL tire bead. Background Art

[0002] As high-end electric vehicles increase the number of batteries and thus the weight of the vehicle due to the need for long mileage and endurance, and relevant regulations restrict the size of tires used on vehicle platforms, the risk of high tire load rates on existing electric vehicle platforms will become increasingly prominent, and the demand for high-load tires is increasing, and HL tires have come into being. HL tires (High Load Capacity Tyres) refer to enhanced load-type tires designed to withstand greater loads at the same standard air pressure. The prefix "HL" must be marked before the tire specification mark on the sidewall of such tires. Since HL tires are an overload capacity tire, the durability of the tire bead is particularly important. There is currently no test method specifically used to evaluate the durability of its tire bead, and a corresponding tire bead durability test method needs to be developed to evaluate its tire bead durability.

[0003] Under the same air pressure and sinking conditions, HL tires can withstand higher loads than ordinary passenger car tires. For HL tires, the bead area is subjected to more stress, so the bead area is designed to be very strong, which makes it easy for the bead to bulge or the bead mouth to be empty. In order to detect the improvement effect of the bead defect problem, a bead durability test is required. At present, there is no relevant national standard method for bead durability test. The laboratory needs to develop a new test method for indoor evaluation of HL bead durability.

[0004] At present, the national recommended standard GB / T 4502-2023 "Indoor Test Method for Passenger Car Tire Performance" is applicable to the durability and low-pressure performance tests of all passenger car tires. The test conditions recommended by the standard are relatively mild and the detection capability of tire damage failure forms is single. For different types of tires, the damage failure forms will vary. It is not suitable for accurately evaluating the tire bead durability performance of HL tires. The mainstream test method for passenger car tire durability in the industry is prone to crown delamination and shoulder hollowing in indoor drum tests, and the test pressure and load are far less than the actual working conditions of HL tires in the market, thus failing to accurately evaluate the tire bead durability performance of HL tires.

[0005] In view of this, it is urgent to develop a test method that can accurately evaluate the bead durability performance of HL tires. Summary of the invention

[0006] In view of the problems existing in the prior art, the object of the present invention is to provide a test method for testing the durability performance of the bead of an HL tire.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A test method for testing the durability of HL tire beads comprises the following steps:

[0009] S1. Install the HL tire on the rim and inflate it to a test pressure of 290 kPa;

[0010] S2. Park the inflated tire-rim assembly at the specified ambient temperature for at least 3 hours;

[0011] S3, installing the tire-rim assembly on an indoor drum testing machine;

[0012] S4. Based on the market conditions of HL tires, select the typical endurance test load and air pressure of HL tires, conduct static load test, and then obtain the deformation of tires under different test loads and air pressures through static load analysis, adjust and determine the test conditions, and then set the HL tire bead endurance test procedure;

[0013] S5. Adjust the test air pressure and start the drum tester to run automatically;

[0014] S6. During the automatic operation of the drum tester, inspections shall be carried out as required, and the machine shall be stopped for inspection and the test pressure shall be adjusted until the machine stops due to tire damage or the program operation is completed;

[0015] S7. Check the tire appearance, remove the tire, and the test is completed.

[0016] Preferably, the prescribed ambient temperature is 38°C±3°C.

[0017] Preferably, in step S4, the HL tire bead durability test procedure includes: setting the tire speed of the first stage to 40 km / h, the test time of the first stage to 24 hours, and the test load to the maximum load of a single tire × 160%; setting an intermediate stop inspection: stop for 10 minutes every 24 hours to check the tire appearance, and stop for 10 minutes every 8 hours after 192 hours to check the tire appearance, until the tire is damaged and the machine is stopped.

[0018] Preferably, in step S5, the adjusting the test air pressure and starting the drum tester to automatically run is specifically: checking the tire pressure after parking and adjusting the test air pressure to 290 kPa, measuring the outer circumference and cross-sectional width of the tire and then starting the drum tester to automatically run, and the ambient temperature is controlled at 38°C ± 3°C during the test.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention combines the market use conditions of HL tires, selects typical durability test loads and air pressures for HL tires, conducts static load tests, and then obtains the deformation of the tires under different test loads and air pressures through static load analysis, adjusts and determines the test conditions, and then provides a method for HL tire bead durability test, which can accurately detect HL tire bead faults. Since the HL tire carries a high load, the bead area is subjected to a large force, and the bead area faults account for a high proportion. Rapidly and accurately detecting the bead durability performance of the HL tire can provide reliable test support for the development of new HL tires and the improvement of HL tire bead performance.

[0021] (2) The tire bead durability test of HL245 / 40R19 101Y was carried out using the test method of the present invention, and the test duration was generally 150h to 200h. The above test verified that the HL tire bead durability test method provided by the present invention can distinguish the test result differences between products with different performances, and the tire damage failures detected by the indoor drum test can basically reflect the tire failure forms on the market.

[0022] (3) Compared with the existing method, the test method of the present invention does not require grinding the tread, nor does it require drilling test holes on the shoulder of the tire. The test operation is simpler, thereby saving time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a test method for testing the durability of HL tire beads proposed by the present invention;

[0024] Figure 2 Durability test results for 5 groups of HL tires with different schemes. DETAILED DESCRIPTION

[0025] 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.

[0026] The present invention combines the market use conditions of HL tires, selects typical endurance test loads and air pressures of HL tires, conducts static load tests, and then obtains the deformation of the tire under different test loads and air pressures through static load analysis, which is used to adjust and determine the test conditions; then, the internal stress conditions of the tire under different loads and air pressures, as well as the flexure zone analysis of the HL tire, are analyzed through FEA to determine the weak points of the tire.

[0027] 1. Selection of representative specifications for test method development:

[0028] Generally, tires with specifications currently being designed and developed are used as tires for developing the test method. The tire specifications used in the present invention are HL245 / 40R19 101Y XL. When the resolution of the method needs to be verified, different design schemes of the specifications or other brands of tires with the same specifications are generally used for verification.

[0029] 2. Market usage conditions and fault information collection:

[0030] As a reference for the development of the test method, it is necessary to pay attention to the common market conditions such as air pressure and load of the models that the HL tires of various specifications are suitable for, as well as the failure information that occurs after the HL tires are used in the market.

[0031] 3. Static load analysis of HL tires:

[0032] Combined with the market conditions of HL tires, the typical endurance test load and air pressure of HL tires were selected for static load test, and the deformation of tires under different test loads and air pressures was obtained. This provides data support for the subsequent adjustment of tire bead endurance test conditions, and further verifies that under the same air pressure and sinking amount, HL tires can withstand higher loads than XL tires.

[0033] 4. Analysis of the flexure area of ​​HL tires to determine the weak points of the tires:

[0034] The internal stress condition of the tire under different load pressures was analyzed by FEA. Based on the previous experience in developing test methods, comprehensive durability test conditions, comprehensive durability test conditions when the basic air pressure was adjusted to 290kPa, air pressure load conditions equivalent to the comprehensive durability test conditions, and reference air pressure / reference load were selected for FEA analysis. The results are shown in Table 1.

[0035] Table 1. Results of FEA analysis of the internal stress of tires at different load pressures

[0036]

[0037] From the results in Table 1, we can see that the internal stress conditions of the tire under different load pressures are analyzed by FEA, and it is concluded that Step 3 in the comprehensive endurance test procedure is the most demanding. Therefore, the Step 3 conditions in the comprehensive endurance test procedure are selected as the basis for subsequent test condition adjustment and verification.

[0038] In order to improve the test efficiency, the bead durability test time is more appropriate to be 150h ~ 200h. At the same time, the bead durability test method can distinguish the differences between HL tires of different specifications. The test results should be able to reflect the main failure forms of HL tires after use in the market.

[0039] As HL tires are prone to bead failure, a bead durability test is required. According to the static load performance analysis of HL tires, when the air pressure is high and the load is large (exceeding the load corresponding to the air pressure), the bead area is subjected to large forces, and the bead and rim edges are also prone to friction, which is a relatively harsh test on the bead area. However, the test speed should not be too high, otherwise it is easy to cause excessive heat generation in the crown (shoulder) and cause shoulder damage before sidewall damage. Therefore, the tire test pressure is 290kPa, and the test load can be set to 160% of the maximum load corresponding to the single tire pressure to increase the bead deflection, and reduce the test speed to 40km / h.

[0040] Example 1

[0041] A test method for testing the durability of HL tire beads comprises the following steps:

[0042] S1. Install the HL tire on the rim and inflate it;

[0043] Specifically, a HL245 / 40R19 101Y tire to be tested with good appearance is mounted on a measuring rim, and the tire is inflated with a test air pressure of 290 kPa;

[0044] S2. Park the inflated tire-rim assembly at the specified ambient temperature for at least 3 hours; park the tire-rim assembly at 38°C ± 3°C for at least 3 hours;

[0045] S3, installing the tire-rim assembly on an indoor drum testing machine with a drum diameter of 1.7 m;

[0046] S4. Referring to Table 2, set the HL tire bead durability test procedure;

[0047] Including: setting the test speed to 40km / h, the first stage test time to 24h, and the test load to the maximum load of a single tire × 160%;

[0048] Set up mid-term inspection stop: Check the tire appearance once every 24 hours for 10 minutes, and check the tire appearance once every 8 hours after 192 hours, until the tire is damaged and the machine is shut down;

[0049] Table 2. HL tire bead durability test procedure

[0050]

[0051]

[0052] S5. Adjust the test pressure and start the drum tester for testing: Check the tire pressure after parking and adjust the test pressure to 290 kPa. After measuring the outer circumference and section width of the tire, start the drum tester for automatic operation. During the test, the ambient temperature is controlled at 38°C ± 3°C.

[0053] S6. Stop due to tire damage or program operation completion: During the automatic operation of the drum tester, inspections, midway stop inspections and adjustment of the test air pressure are carried out as required until the tire is damaged and the tester stops;

[0054] S7. Check the tire appearance, remove the tire, and the test ends;

[0055] S8. Use FEA to analyze the internal stress conditions of the tire under different load pressures, as well as the flexure zone analysis of the HL tire to determine the weak points of the tire.

[0056] The test conditions of the test method of the present invention were verified using HL tires. Specifically, five groups of HL tires with different schemes were used for durability tests. The results are shown in Tables 3 and Figure 2 .

[0057] Table 3. Durability test results of HL tires with 5 different schemes

[0058]

[0059]

[0060] The results in Table 3 show that the average running time of the test tires is 163.5 h, which indicates that the test time obtained by the method of the present invention is appropriate; Figure 2 The results show that the damage of each tire occurs at the bead area.

[0061] It should be noted here that the three elements of the indoor tire drum durability test are speed, load and air pressure, and the ambient temperature and test time are a total of five variables. Different test procedures obtained by adjusting these variables will also achieve the same test purpose, which will not be elaborated here.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and improved concepts of the present invention within the technical scope disclosed by the present invention, and they should be covered by the protection scope of the present invention.

Claims

1. A test method for testing the durability of HL tire beads, characterized in that: The following steps are involved: S1. Install the HL tire on the rim and inflate it to a test pressure of 290 kPa; S2. Park the inflated tire-rim assembly at the specified ambient temperature for at least 3 hours; S3, installing the tire-rim assembly on an indoor drum testing machine; S4. Based on the market conditions of HL tires, select the typical endurance test load and air pressure of HL tires, conduct static load test, and then obtain the deformation of tires under different test loads and air pressures through static load analysis, adjust and determine the test conditions, and then set the HL tire bead endurance test procedure; S5. Adjust the test air pressure and start the drum tester to run automatically; S6. During the automatic operation of the drum tester, inspections shall be carried out as required, and the machine shall be stopped for inspection and the test pressure shall be adjusted until the machine stops due to tire damage or the program operation is completed; S7. Check the tire appearance, remove the tire, and the test is completed.

2. The test method for testing the durability of HL tire beads according to claim 1, characterized in that: The specified ambient temperature is 38°C ± 3°C.

3. The test method for testing the durability of HL tire beads according to claim 1, characterized in that: In step S2, the HL tire bead durability test procedure includes: setting the tire speed of the first stage to 40km / h, the test time of the first stage to 24h, and the test load to the maximum load of a single tire × 160%; setting the mid-term stop inspection: stop for 10min every 24h to check the tire appearance once, and stop for 10min every 8h after 192h to check the tire appearance once, until the tire is damaged and the machine is stopped.

4. The test method for testing the durability of HL tire beads according to claim 1, characterized in that: In step S5, the step of adjusting the test pressure and starting the drum tester to automatically run is as follows: checking the tire pressure after parking and adjusting the test pressure to 290 kPa, measuring the outer circumference and cross-sectional width of the tire and then starting the drum tester to automatically run, and controlling the ambient temperature at 38°C ± 3°C during the test.

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