JP7397280B2 - Tire rubber abrasion property testing method and abrasion property testing machine - Google Patents

Description

The present invention relates to a tire rubber abrasion characteristic testing method and abrasion characteristic testing machine, and more particularly to a tire rubber abrasion characteristic testing method and abrasion characteristic testing machine that can improve the test accuracy of abrasion tests using test pieces. .

In recent methods for testing wear characteristics of tire rubber, a test piece of the tread rubber of an actual tire is created, a rotating body with a simulated road surface that reproduces a specified actual road surface is created, and the test piece is tested under specified test conditions. A wear test is being conducted in which a rotating body is brought into contact with a simulated road surface. As such a conventional wear characteristic testing method, the technique described in Patent Document 1 is known.

Patent No. 6444720

An object of the present invention is to provide a tire rubber wear property testing method and a wear property testing machine that can improve the test accuracy of wear tests using test pieces.

In order to achieve the above object, the method for testing the wear characteristics of tire rubber according to the present invention includes a test piece preparation step of preparing a test piece of tread rubber of an actual tire, and a rotating test piece having a simulated road surface that reproduces a predetermined actual road surface. A method for testing wear characteristics of tire rubber, comprising: a step of creating a rotating body, and a wear test step of bringing the test piece into contact with the simulated road surface of the rotating body under predetermined test conditions, In the wear test step, the slip angle of the test piece is continuously changed in a sawtooth waveform or a sinusoidal waveform .

Further, the tire rubber wear characteristic tester according to the present invention includes a rotating body having a simulated road surface that reproduces a predetermined actual road surface, and a test piece of tread rubber of an actual tire being grounded on the simulated road surface of the rotating body. A tire rubber abrasion characteristics tester comprising a test piece holding device for holding a test piece, the test piece holding device controlling the slip angle of the test piece so as to continuously change the slip angle of the test piece in a sawtooth waveform or a sine wave shape. Department.

According to the tire rubber wear characteristic test method and wear characteristic tester according to the present invention, (1) a test piece and a simulated road surface are used to conduct the wear test, so that it can be compared with a wear test using an actual tire; This has the advantage of shortening the test time to obtain the wear characteristics of tread rubber. Moreover, uneven wear of the test piece is suppressed compared to a configuration in which the wear test is performed with the slip angle of the test piece fixed at 0 [deg] or a predetermined angle. This has the advantage of improving test accuracy.

FIG. 1 is a plan view showing a tire rubber wear characteristic tester according to an embodiment of the present invention. FIG. 2 is a front view showing a tire rubber wear characteristic tester according to an embodiment of the present invention. FIG. 3 is a flowchart showing a method for testing the wear characteristics of tire rubber according to an embodiment of the present invention. FIG. 4 is a flowchart showing the rotating body manufacturing step in the wear characteristic testing method shown in FIG. FIG. 5 is an explanatory diagram showing an example of a change in slip angle. FIG. 6 is a chart showing the results of the wear test according to the embodiment of the present invention.

Hereinafter, this invention will be explained in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. Further, the constituent elements of this embodiment include elements that can be replaced while maintaining the identity of the invention and are obvious to be replaced. Further, the plurality of modifications described in this embodiment can be arbitrarily combined within the range obvious to those skilled in the art.

[Abrasion characteristics tester]
FIGS. 1 and 2 are a plan view (FIG. 1) and a front view (FIG. 2) showing a tire rubber wear characteristic tester according to an embodiment of the present invention. These figures schematically show a turntable-type wear characteristic tester 1 as an example.

As shown in FIG. 1, the wear property testing machine 1 includes a rotating body 2, a test piece holding device 3, and a temperature control device 4.

The rotating body 2 is a so-called turntable, and is driven by a drive device (not shown) to rotate at a predetermined rotational speed, which will be described later. Further, the rotating body 2 has a simulated road surface 21 that reproduces a predetermined actual road surface on its upper surface, and rotates with this simulated road surface 21 horizontal. Further, the simulated road surface 21 is formed as a separate member by a creation method described later, and this member is attached to the upper surface of the rotating body 2.

The test piece holding device 3 holds a cylindrical test piece S, which will be described later, with the circumferential surface of the test piece S being in contact with the simulated road surface 21 of the rotating body 2 . Specifically, as shown in FIG. 2, the test piece holding device 3 includes a holding part 31, and the holding part 31 rotatably holds a cylindrical test piece S. Further, by moving the holding portion 31 back and forth in the axial direction of the rotating body 2, the ground contact state between the test piece S and the simulated road surface 21 is switched. Furthermore, the holding portion 31 controls the pressing force of the test piece S against the simulated road surface 21, thereby controlling the ground load of the test piece S. Further, as shown in FIG. 1, the test specimen holding device 3 includes a slip angle control section 32, and the slip angle control section 32 rotates around the holding section 31, so that the holding section 31 is moved on the simulated road surface 21. As the test piece S rotates, the slip angle of the test piece S changes. Note that in FIG. 2, illustration of the slip angle control section 32 is omitted.

The temperature control device 4 controls the surface temperature of the simulated road surface 21 of the rotating body 2 to a predetermined temperature, which will be described later. For example, as shown in FIG. 2, the rotating body 2 may include a refrigerant flow path R therein, and the temperature control device 4 may supply a refrigerant at a predetermined temperature to the inside of the rotating body through the rotating shaft of the rotating body 2. Accordingly, the surface temperature of the simulated road surface 21 is controlled.

[Wear characteristics test method]
FIG. 3 is a flowchart showing a method for testing the wear characteristics of tire rubber according to an embodiment of the present invention. FIG. 4 is a flowchart showing the rotating body production step ST2 in the wear characteristic testing method shown in FIG. FIG. 5 is an explanatory diagram showing an example of a change in slip angle.

This abrasion characteristic test method is a test in which a test piece S of tread rubber of an actual tire is brought into contact with a simulated road surface 21 that reproduces a predetermined actual road surface, and wear characteristic data of the test piece S is obtained. be exposed.

In the test piece creation step ST1, a test piece S is created. The test piece S is made of the same rubber material as the tread rubber of an actual tire (not shown), and is formed into a cylindrical shape. Further, the cylindrical side surface corresponds to the tread surface of the tire. Moreover, it is preferable that the outer diameter of the cylindrical shape of the test piece S is in the range of 1/12 or more and 1/6 or less of the outer diameter of the actual tire. Moreover, it is preferable that the height of the cylindrical shape of the test piece S is in the range of 1/20 or more and 1/9 or less of the ground contact width of the actual tire.

The ground contact length of the test piece S is calculated as the average value of the ground contact lengths of the cylindrical side surfaces in a predetermined ground contact area. The outer diameter of the actual tire is calculated as the tire outer diameter when the tire is mounted on a predetermined rim and a predetermined internal pressure is applied. The ground contact length of an actual tire is calculated as the average value of the tire ground contact length in a predetermined ground contact area when the tire is mounted on a predetermined rim, a predetermined internal pressure is applied, and a predetermined load is applied. The above-mentioned predetermined rim, predetermined internal pressure, predetermined load, and predetermined ground contact area are appropriately selected according to the test purpose and test conditions.

In the rotating body creation step ST2, a rotating body 2 having a simulated road surface 21 that reproduces a predetermined actual road surface is created. Specifically, the rotating body creation step ST2 is performed as follows (see FIG. 4).

In the road surface data acquisition step ST21, road surface data of a predetermined actual road surface is acquired. For example, three-dimensional data of an actual road surface is acquired using a laser scanner and used as road surface data of the actual road surface. The road surface data of the actual road surface includes position data and depth data (that is, data in the height direction of the uneven portions of the actual road surface) in a predetermined area of the actual road surface.

In the road surface roughness calculation step ST22, the micro roughness and macro roughness of the actual road surface are calculated from the road surface data. Specifically, road surface data is subjected to FFT (fast Fourier transform) analysis and classified into a plurality of waveform data having mutually different wavelengths. Then, these waveform data are classified into a first waveform data group having a wavelength shorter than a predetermined threshold value and a second waveform data group having a longer wavelength. For example, when the actual road surface is a general paved road, the wavelength threshold is selected from a range of 0.5 mm or more and 1.0 mm or less. Next, composite waves of the first and second waveform data groups are calculated, and the surface roughness of each waveform data group is calculated. Then, the surface roughness of the first waveform data group with a short wavelength is defined as the micro-roughness of the actual road surface, and the surface roughness of the second waveform data group with the long wavelength is defined as the macro-roughness of the actual road surface. . Note that micro roughness corresponds to the surface roughness of an actual road surface where only relatively fine irregularities are extracted, and macro roughness corresponds to the surface roughness of an actual road surface where only relatively coarse irregularities are extracted. do. Further, the surface roughness is selected from, for example, arithmetic mean roughness, ten-point mean roughness, and the like.

In the macro roughness correction step ST23, the macro roughness of the actual road surface described above is corrected using the outer diameter ratio or ground contact length ratio of the test piece S and the actual tire. Specifically, first, the outer diameter or ground contact length of the test piece S having a cylindrical shape is measured. Next, the outer diameter or contact length of the actual tire is measured. Next, the ratio between the calculated outer diameter or contact length of the actual tire and the outer diameter or contact length of the test piece S having a cylindrical shape is calculated. Then, the product of the macro roughness of the actual road surface described above and the outer diameter ratio or ground contact length ratio of the test piece S and the actual tire described above is calculated and used as the corrected macro roughness. Conceptually, since the outer diameter and ground contact length of the test specimen S are smaller than the outer diameter and ground contact length of the actual tire, the surface roughness of the second waveform data group having a long wavelength defined by the above threshold value is Reduced. Further, the wavelength of the waveform data group is used without being corrected.

On the other hand, the micro-roughness of the actual road surface described above is not corrected. That is, the surface roughness and wavelength of the waveform data group having a short wavelength defined by the threshold value are used without being corrected. However, when creating a simulated road surface 21 to be described later, manufacturing errors may occur in the micro-roughness of the actual road surface. In this case, it is preferable that the manufacturing error is within ±10%.

In the simulated road surface creation step ST24, a simulated road surface 21 having the micro-roughness of the actual road surface and the corrected macro-roughness is created. That is, the surface roughness of the actual road surface is partially corrected and reproduced on the simulated road surface 21. As a method for creating the simulated road surface 21, a known method can be adopted. For example, a method may be adopted in which aggregate (eg, ceramic aggregate) that can reproduce the micro-roughness of an actual road surface and the corrected macro-roughness is compacted by compacting with an adhesive (eg, epoxy resin). Then, the simulated road surface 21 created above is pasted on the upper surface of the rotating body 2, and the rotating body 2 is created.

In FIG. 3, in the wear test step ST3, under predetermined test conditions, the test piece S is pressed against the simulated road surface 21 of the rotating body 2 and comes into contact with the ground, and as the rotating body 2 rotates, the test piece S wears out. progresses. Specifically, the test piece holding device 3 rotatably holds the test piece S and presses the circumferential surface of the test piece S against the simulated road surface 21 of the rotating body 2 to ground it (see FIG. 2). At this time, the grounding load of the test piece S is controlled by the test piece holding device 3 controlling the pressing force of the test piece S. Then, the wear state of the test piece S is observed, and wear characteristic data of the test piece S is acquired. As the test conditions, for example, the ground load of the test piece S, the surface temperature of the simulated road surface 21, the rotational speed of the rotating body, and the slip angle of the test piece S are set.

The grounding load of the test piece S is applied to the test piece S via the holding part 31 (see FIG. 2) of the test piece holding device 3 described above. In addition, the ground contact load of the test piece S is the ground contact pressure of the test piece S when the real tire is mounted on a predetermined rim, a predetermined internal pressure is applied, and a predetermined load is applied. It is set so that it is equal to the pressure. The ground pressure of the test piece S is defined as the contact pressure between the circumferential surface of the test piece S and the simulated road surface 21 when the test piece S is pressed against the simulated road surface 21 of the rotating body 2. As a method for calculating the ground load of the test piece S, a known method may be adopted.

The surface temperature of the simulated road surface 21 is controlled to a predetermined temperature by the temperature control device 4 described above. Further, the surface temperature of the simulated road surface 21 is set lower than the room temperature of the test chamber in order to accelerate the progress of wear of the test piece S. Specifically, the surface temperature of the simulated road surface 21 is preferably set to a range of 0 [°C] to 23 [°C], and preferably set to a range of 5 [°C] to 15 [°C]. More preferred. The above lower limit prevents the simulated road surface 21 from freezing, and the above upper limit appropriately promotes the progress of wear on the test piece S.

The rotational speed of the rotating body 2 is controlled by the drive control of the rotating body 2 described above. Further, the rotational speed of the rotating body 2 is set so that the running speed of the test piece S on the simulated road surface 21 is faster than a predetermined average speed of the actual vehicle. Specifically, the outer diameter ratio or ground contact length ratio of the test piece S and the actual tire described above is used to convert the average speed of the actual vehicle to the running speed of the test piece S, and this conversion value is used to calculate the rotational body. 2 rotation speeds are set. Further, as the actual vehicle average speed, the average speed of passing vehicles on the target actual road surface (for example, the speed limit of the road) is selected. Further, it is preferable that the relative speed between the test piece S and the simulated road surface 21 is in a range of 1.05 times or more and 5.0 times or less of the above-mentioned average speed of the actual vehicle.

The slip angle of the test piece S is given to the test piece S by the slip angle control section 32 of the test piece holding device 3 described above. Further, the slip angle of the test piece S is set so as to change continuously over time in order to suppress uneven wear of the test piece S. Further, it is preferable that the slip angle is set to continuously change within a range of −20 [deg] or more and 20 [deg] or less. Furthermore, the slip angle may change, for example, in a sawtooth waveform (see FIG. 5) or in a sinusoidal waveform (figures omitted).

[effect]
As explained above, this method for testing wear characteristics of tire rubber includes a test piece creation step ST1 of creating a test piece S of tread rubber of an actual tire, and a rotating body having a simulated road surface 21 that reproduces a predetermined actual road surface. 2 (see FIGS. 1 and 2), and a wear test step ST3 in which the test piece S is brought into contact with the simulated road surface 21 of the rotor 2 under predetermined test conditions (see FIGS. 1 and 2). (See 3). Furthermore, in the wear test step ST3, the slip angle of the test piece S is continuously changed (see FIG. 1).

In this configuration, (1) the test piece S and the simulated road surface 21 are used to conduct the wear test, so the test time for obtaining the wear characteristics of the tread rubber is reduced compared to the wear test using an actual tire. It has the advantage of being shortened. Furthermore, (2) uneven wear of the test piece S is suppressed compared to a configuration in which the wear test is performed with the slip angle of the test piece S fixed at 0 [deg] or a predetermined angle. This has the advantage of improving test accuracy.

Furthermore, in the method for testing the wear characteristics of tire rubber according to the present invention, the surface temperature of the simulated road surface 21 is controlled to a predetermined temperature in the wear test step ST3. This has the advantage that the temperature of the contact surface between the simulated road surface 21 and the test piece S is optimized, and the reproducibility accuracy of the wear test is improved. In particular, in wear tests using real tires, it is difficult to stably control the surface temperature of the simulated road surface because the tire's ground contact area is large. In this respect, a wear test using a small test piece S is useful in that the surface temperature of the simulated road surface can be appropriately controlled.

Furthermore, in the method for testing the wear characteristics of tire rubber according to the present invention, the surface temperature of the simulated road surface 21 is controlled to a temperature lower than room temperature. This has the advantage that the wear of the test piece S is accelerated and the test time can be shortened.

Furthermore, in the tire rubber abrasion characteristic testing method according to the present invention, in the abrasion test step ST3, the rotating body 2 is The rotation speed of is controlled. This has the advantage that the wear of the test piece S is accelerated and the test time can be shortened.

Further, the tire rubber wear characteristic tester 1 according to the present invention includes a rotating body 2 having a simulated road surface 21 that reproduces a predetermined actual road surface, and a test piece S of tread rubber of an actual tire on the simulated road surface of the rotating body 2. 21 (see FIGS. 1 and 2). Further, the test piece holding device 3 includes a slip angle control section 32 that continuously changes the slip angle of the test piece S.

In this configuration, (1) the test piece S and the simulated road surface 21 are used to conduct the wear test, so the test time for obtaining the wear characteristics of the tread rubber is reduced compared to the wear test using an actual tire. It has the advantage of being shortened. Furthermore, (2) uneven wear of the test piece S is suppressed compared to a configuration in which the wear test is performed with the slip angle of the test piece S fixed at 0 [deg] or a predetermined angle. This has the advantage of improving test accuracy.

Further, the tire rubber wear characteristic tester 1 according to the present invention includes a temperature control device 4 that controls the surface temperature of the simulated road surface 21. This configuration has the advantage that the temperature of the contact surface between the simulated road surface 21 and the test piece S is optimized, and the reproducibility accuracy of the wear test is improved. In particular, in wear tests using real tires, it is difficult to stably control the surface temperature of the simulated road surface because the tire's ground contact area is large. In this respect, a wear test using a small test piece S is useful in that the surface temperature of the simulated road surface can be appropriately controlled.

FIG. 6 is a chart showing the results of the wear test according to the embodiment of the present invention.

First, as a wear test of a real tire, a real tire with a tire size of 215/60R16 was assembled on a rim with a rim size of 16×6.5J, and an air pressure of 230 [kPa] was applied to this real tire. The actual tires will also be installed on a four-wheeled sedan, which will be a test vehicle. Then, the test vehicle runs on a predetermined test course at an average speed of 16 [km/h], and the state of wear is observed when the actual tires are worn down to a predetermined amount of wear.

Next, as a wear test using a test piece, a cylindrical test piece made of the same rubber material as the tread rubber of the actual tire is created. Further, the outer diameter of the test piece is set to 1/8 of the outer diameter of the actual tire. Additionally, a simulated road surface is created that reproduces the surface roughness of the actual road surface on the test course. Further, the macro roughness and micro roughness of the simulated road surface are defined using a wavelength of 0.5 [mm] as a threshold value. The test piece is pressed against the simulated road surface of the rotating body, and the same ground contact pressure as the tire ground pressure in the actual tire wear test is applied to the test piece.

Then, the wear state of the actual tire and the wear state of the test piece are compared, and the test accuracy of the wear test using the test piece is evaluated. This evaluation is calculated using a correlation coefficient, and the closer the value is to 1.00, the better. In addition, the test time until the test piece wears down to a predetermined amount of wear is measured. This evaluation is performed by index evaluation using Comparative Example 1 as a standard (100), and the smaller the numerical value, the shorter the test time is preferable.

Further, in FIG. 6, in Comparative Example 1, the macro roughness and micro roughness of the simulated road surface are set to be the same (1/1) as the actual road surface. Further, the temperature of the simulated road surface is room temperature (24 [° C.]) and is not controlled. Further, the rotational speed of the rotating body is set so that the running speed of the test piece on the simulated road surface is a conversion value (2.1) of the average speed of the actual vehicle (16 [km/h]). Further, the slip angle of the test piece was fixed at 9 [deg]. Comparative Example 2 differs from Comparative Example 1 in that only the micro-roughness of the simulated road surface is set to be the same as the actual road surface, and the macro-roughness is set to 0.

In addition, in Example 1, compared to Comparative Example 1, only the micro-roughness of the simulated road surface was set to be the same as the actual road surface, and the macro-roughness was set to 1/8 the macro-roughness of the actual road surface (test piece and actual road surface). The difference is that it is set to a reduced value (same as the tire outer diameter ratio). Further, the slip angle of the test piece continuously changes within a range of ±9 [deg]. Example 2 differs from Example 1 in that the temperature of the simulated road surface is set to a temperature lower than room temperature (10 [° C.]). Example 3 differs from Example 2 in that the running speed of the test piece on the simulated road surface is set to the converted value (13) when the average speed of the actual vehicle is 100 [km/h]. .

As the test results show, the test methods of Examples 1 to 3 can reduce the test time while improving the test accuracy of the wear test using the test piece.

1 Wear property tester; 2 Rotating body; 21 Simulated road surface; 3 Test piece holding device; 31 Holding section; 32 Slip angle control section; 4 Temperature control device

Claims (8)

a test piece creation step of creating a test piece of tread rubber of an actual tire; a rotating body creation step of creating a rotating body having a simulated road surface that reproduces a predetermined actual road surface; A method for testing wear characteristics of tire rubber, comprising: a wear test step of bringing the rotating body into contact with the simulated road surface,
A method for testing wear characteristics of tire rubber, characterized in that in the wear test step, the slip angle of the test piece is continuously changed in a sawtooth wave shape or a sinusoidal wave shape . The tire rubber wear characteristic testing method according to claim 1, wherein in the wear testing step, the surface temperature of the simulated road surface is controlled to a predetermined temperature. The method for testing wear characteristics of tire rubber according to claim 2, wherein the surface temperature of the simulated road surface is controlled to be lower than room temperature. Any one of claims 1 to 3, wherein in the wear test step, the rotation speed of the rotating body is controlled so that the relative speed between the test piece and the simulated road surface is faster than a predetermined average speed of the actual vehicle. A method for testing the wear characteristics of tire rubber described in . Wear characteristics of tire rubber, comprising a rotating body having a simulated road surface that reproduces a predetermined actual road surface, and a test piece holding device that holds a test piece of tread rubber of an actual tire in contact with the simulated road surface of the rotating body. A testing machine,
A wear characteristic tester for tire rubber, wherein the test piece holding device includes a slip angle control section that continuously changes the slip angle of the test piece in a sawtooth wave shape or a sine wave shape . The tire rubber wear characteristic testing machine according to claim 5, further comprising a temperature control device that controls the surface temperature of the simulated road surface. The method for testing wear characteristics of tire rubber according to any one of claims 1 to 4, wherein the slip angle changes continuously within a range of -20 [deg] or more and 20 [deg] or less. The tire rubber wear characteristic tester according to claim 5 or 6, wherein the slip angle changes continuously within a range of −20 [deg] or more and 20 [deg] or less.

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