How to measure tires

Abstract

To provide a tire measuring method that can accurately measure uniformity of a tire.SOLUTION: A method for measuring uniformity of a tire includes: a mounting step S1 of mounting a tire on a rim; a preliminary step S2 of adjusting air pressure of the tire to first air pressure to allow the tire to travel; and a measurement step S3 of adjusting the air pressure of the tire to second air pressure to measure uniformity of the tire. The first air pressure is lower than the second air pressure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for measuring tire uniformity. [Background technology]

[0002] Conventionally, various methods for measuring tire uniformity have been proposed. For example, Patent Document 1 below proposes a tire uniformity measuring method in which, when mounting a tire on a rim, the tire is adjusted to an air pressure higher than the measured air pressure, thereby improving the fitting between the tire and the rim. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-047248 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the measurement method disclosed in Patent Document 1 has a problem in that the measurement varies widely and is poor in accuracy when it comes to tires with high rigidity in the sidewall portion, such as run-flat tires.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire measuring method capable of measuring tire uniformity with high accuracy. [Means for solving the problem]

[0006] The present invention is a method for measuring tire uniformity, comprising: a mounting step of mounting the tire on a rim; a preliminary step of adjusting the air pressure of the tire to a first air pressure and running the tire; and a measurement step of adjusting the air pressure of the tire to a second air pressure and measuring the uniformity of the tire, wherein the first air pressure is lower than the second air pressure.

[0007] In the tire measuring method of the present invention, it is desirable that the first air pressure is 10% to 90% of the second air pressure.

[0008] In the tire measuring method of the present invention, it is desirable that the first air pressure is 10% to 40% of the second air pressure.

[0009] In the tire measuring method of the present invention, it is preferable that in the preliminary step, the tire is run under the same load as in the measuring step.

[0010] In the tire measuring method of the present invention, it is preferable that in the mounting step, the air pressure of the tire is adjusted to a third air pressure higher than the second air pressure, and the tire is tightly attached to the rim.

[0011] In the tire measuring method of the present invention, the tire is preferably a run-flat tire. Effect of the Invention

[0012] The tire measurement method of the present invention includes a preliminary step of adjusting the tire air pressure to a first air pressure and running the tire, and a measurement step of adjusting the tire air pressure to a second air pressure and measuring the uniformity of the tire, wherein the first air pressure is lower than the second air pressure.

[0013] In this tire measuring method, a tire adjusted to a small first air pressure is run, so that distortion can be generated in the bead portion due to bending of the sidewall portion, improving the fitting between the tire and the rim. Therefore, the tire measuring method of the present invention has small variation when measuring tire uniformity, and can measure tire uniformity with high accuracy. [Brief description of the drawings]

[0014] [Figure 1] 1 is a flowchart showing an embodiment of a tire measurement method of the present invention. [Diagram 2] 1 is a graph showing the results of an RFV test. [Diagram 3] 13 is a graph showing the results of the R1H test. [Figure 4] 1 is a graph showing the results of a LFV test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a flow chart showing a tire measurement method of the present embodiment. The tire measurement method of the present embodiment is a method for measuring the uniformity of a tire. As shown in Fig. 1, the tire measurement method of the present embodiment first performs a mounting step S1 of mounting a tire on a rim.

[0016] The tire is, for example, a pneumatic tire to be measured. The tire of this embodiment is a run-flat tire. The tire measurement method of this embodiment can accurately measure the uniformity of a tire even if the tire to be measured is a run-flat tire.

[0017] The rim is, for example, a genuine rim. Here, a "genuine rim" is a rim that is determined for each tire by a standard system that includes the standard on which the tire is based, for example, a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO. A "genuine rim" is a rim that is determined for each tire by a manufacturer or the like when there is no standard system that includes the standard on which the tire is based. The rim may be attached to the uniformity measuring device in advance, for example.

[0018] In the tire measurement method of this embodiment, after the mounting step S1, a preliminary step S2 is performed in which the tire is adjusted to a first air pressure and the tire is run. In the preliminary step S2, the tire is pressed against a rotating drum of the uniformity measuring device and rotated for a predetermined time while a specified load is applied. This preliminary step S2 brings the tire and the rim into close contact with each other, thereby reducing variation during uniformity measurement.

[0019] In the tire measurement method of the present embodiment, after the preliminary step S2, a measurement step S3 is performed in which the tire air pressure is adjusted to the second air pressure and the tire uniformity is measured. In the measurement step S3, for example, the tire is pressed against a rotating drum of the uniformity measuring device and rolled under a normal load.

[0020] Here, the "normal load" is the load determined for each tire by each standard in the standard system including the standard on which the tire is based, such as "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. When there is no standard system including the standard on which the tire is based, the "normal load" is the load determined for each tire by the manufacturer, etc.

[0021] In the measurement step S3, for example, radial force variation (hereinafter referred to as "RFV"), which is a force that varies in the radial direction of the tire, and lateral force variation (hereinafter referred to as "LFV"), which is a force that varies in the axial direction of the tire, are measured when the tire is rolled. In the measurement step S3, it is preferable to further measure the first harmonic (hereinafter referred to as "R1H") of the RFV and the first harmonic (hereinafter referred to as "L1H") of the LFV.

[0022] The first air pressure in this embodiment is smaller than the second air pressure. In this tire measurement method, a tire adjusted to a small first air pressure is run, so that distortion can be generated in the bead portion due to the bending of the sidewall portion, and the fitting between the tire and the rim can be improved. Therefore, the tire measurement method of this embodiment can measure the tire uniformity with small variation even in a tire with a high rigidity of the sidewall portion such as a run-flat tire, and can measure the tire uniformity with high accuracy.

[0023] In a more preferred embodiment, in the fitting step S1, the tire is fitted tightly to the rim by adjusting the tire pressure to a third pressure higher than the second pressure. Such a fitting step S1 can further improve the fitting between the tire and the rim.

[0024] In the preliminary step S2 of this embodiment, the tire is run under the same load as in the measurement step S3. That is, the specified load in the preliminary step S2 is the normal load. In such a preliminary step S2, there is no risk of an excessive load being applied to the tire, and residual stress can be reduced.

[0025] The tire rolling time in the preliminary step S2 is preferably 5 to 20 seconds. A rolling time of 5 seconds or more can reliably improve the fitting between the tire and the rim. A rolling time of 20 seconds or less can shorten the measurement time, allowing tire uniformity to be measured efficiently.

[0026] The first air pressure is preferably 10% to 90% of the second air pressure. By setting the first air pressure to 10% or more of the second air pressure, excessive distortion in the tire can be suppressed, and tire uniformity can be measured with high accuracy. By setting the first air pressure to 90% or less of the second air pressure, fitting between the tire and the rim can be improved, and tire uniformity can be measured with high accuracy.

[0027] From this viewpoint, the first air pressure is more preferably 10% to 40% of the second air pressure. In particular, when the tire is a run-flat tire, the first air pressure being 40% or less of the second air pressure allows the highly rigid sidewall portion to bend, and ensures that distortion is generated in the bead portion.

[0028] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified in various ways. EXAMPLES

[0029] An embodiment in which the uniformity of run-flat tires is measured using the method shown in Figure 1 and a comparative example in which the preliminary step has the same air pressure as the measurement step were tested. In the test, the uniformity was measured 10 times for the same tire. The common specifications and measurement conditions are as follows:

[0030] <Common specifications> Tire size: 245 / 50RF19 Load capacity: 5.97kN

[0031] <Measurement conditions> Comparative Example Example Air pressure for preliminary process: 200kPa 50kPa Air pressure during measurement: 200kPa 200kPa

[0032] The results of the tests are shown in Figures 2 to 4. Figure 2 is a graph showing the results of the RFV tests. Figure 3 is a graph showing the results of the R1H tests. Figure 4 is a graph showing the results of the LFV tests.

[0033] As is clear from Figs. 2 to 4, the uniformity measured in the examples showed smaller variations when measured 10 times for all of RFV, R1H, and LFV than the uniformity measured in the comparative example, confirming that the tire uniformity was measured with high accuracy. [Explanation of symbols]

[0034] S1 Installation process S2 Preliminary process S3 measurement process

Claims

1. A method for measuring tire uniformity, the method comprising: a mounting step of mounting the tire on a rim; a preliminary step of adjusting the air pressure of the tire to a first air pressure and running the tire; and a measuring step of adjusting the air pressure of the tire to a second air pressure and measuring the uniformity of the tire, The first air pressure is less than the second air pressure. How to measure tires.

2. 2. The tire measuring method according to claim 1, wherein the first air pressure is 10% to 90% of the second air pressure.

3. 2. The tire measuring method according to claim 1, wherein the first air pressure is 10% to 40% of the second air pressure.

4. 4. The tire measuring method according to claim 1, wherein the preliminary step comprises running the tire under the same load as that applied in the measuring step.

5. 5. The tire measuring method according to claim 1, wherein the mounting step includes adjusting an air pressure of the tire to a third air pressure higher than the second air pressure, and fitting the tire to the rim.

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