JP2021088319A - Evaluation method of tire - Google Patents

Abstract

To provide an evaluation method of a tire T which can quantitatively evaluate easiness to be assembled to a rim R.SOLUTION: This evaluation method includes: (1) a process for assembling a tire T to a rim R and adjusting internal pressure of the tire T; (2) a process for moving the rim R toward a table 12 positioned just below the rim R and bringing the tire T into contact with the table 12; and (3) a process for moving the table 12 in an axial direction of the tire T with respect to the rim R and deforming the tire T. In the contact process, longitudinal load is given to the tire T. In the deformation process, displacement of the tire T and lateral load acting on the tire T are measured. The internal pressure of the tire T is 100kPa or less, and the longitudinal load is 1.5 kN or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire evaluation method.

When assembling a tire to a rim, a rim assembling machine (not shown) such as a tire changer is used. In this rim assembly machine, the jig is pressed against the bead portion while the operator rotates the tire and pushes the side portion with the palm. As a result, the bead portion fits inside the flange.

Ease of assembly with the rim of a tire (hereinafter referred to as ease of assembly with the rim) is one of the important performances. Until now, the ease of assembling with the rim has been evaluated by the sense of the operator. In the evaluation based on the sense of the operator, that is, the sensory evaluation, the result tends to vary depending on the person who evaluates. Therefore, it has been studied to quantitatively evaluate the ease of assembling with the rim so that the ease of assembling with the rim can be expressed by a numerical value that can be compared (for example, Patent Document 1 below).

Japanese Unexamined Patent Publication No. 2019-151161

In order to assemble the tire on the rim, the operator needs to push the side part to deform the side part to some extent. Tires that are easy for workers to deform the side parts are easy to assemble on the rim, and tires that are difficult for workers to deform the side parts are difficult to assemble on the rim. If the rigidity of the side portion can be grasped in consideration of the condition of the tire assembled on the rim, it is expected that the ease of assembling with the rim can be quantitatively evaluated, which correlates with the sensory evaluation by the operator. However, a technique that can grasp the rigidity of the side portion in consideration of the condition of the tire assembled on the rim has not been established.

The present invention has been made in view of such an actual situation, and an object of the present invention is to provide a tire evaluation method capable of quantitatively evaluating the ease of assembling with a rim.

The method for evaluating a tire according to one aspect of the present invention is
(1) A process of assembling a tire on a rim and adjusting the internal pressure of the tire.
(2) The step of moving the rim toward a table located directly below the rim and bringing the tire into contact with the table, and (3) moving the table with respect to the rim in the axial direction of the tire. The step of deforming the tire is included. In the contact step, a vertical load is applied to the tire, and in the deformation step, the displacement of the tire and the lateral load acting on the tire are measured. The internal pressure of the tire is 100 kPa or less, and the vertical load is 1.5 kN or less.

Preferably, in this tire evaluation method, the internal pressure of the tire is 25 kPa or more and 75 kPa or less.

Preferably, in this tire evaluation method, the longitudinal load is 0.75 kN or more and 1.25 kN or less.

Preferably, in this tire evaluation method, the table comprises a mounting surface that comprises a flat surface and is in contact with the tire. The area of the previously described mounting surface is larger than the area of the contact surface formed by the tire coming into contact with the previously described mounting surface.

The method for evaluating a tire according to another aspect of the present invention is as follows.
(1) A process of assembling a tire on a rim and adjusting the internal pressure of the tire.
(2) The step of moving the rim toward a table located directly below the rim and bringing the tire into contact with the table, and (3) moving the table with respect to the rim in the axial direction of the tire. The step of deforming the tire is included. In the contact step, a vertical load is applied to the tire, and in the deformation step, the displacement of the tire and the lateral load acting on the tire are measured.

In the tire evaluation method of the present invention, the rigidity of the side portion can be grasped in consideration of the state of the tire assembled on the rim. This evaluation method can quantitatively evaluate the ease of assembling with the rim.

FIG. 1 is a front view showing a rigidity evaluation device used in the tire evaluation method according to the embodiment of the present invention. FIG. 2 is a side view of the rigidity evaluation device shown in FIG. FIG. 3 is a graph showing the relationship between the displacement of the tire and the lateral load acting on the tire.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

In the present invention, the state in which the tire is incorporated in the normal rim, the internal pressure of the tire is adjusted to the normal internal pressure, and no load is applied to the tire is referred to as a normal state. The dimensions and angles of each part of the tire are usually measured under normal conditions.

Regular rims are rims defined in the standards on which the tire relies. The "standard rim" in the JATTA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are regular rims.

Regular internal pressure means the internal pressure defined in the standard on which the tire relies. The "maximum air pressure" in the JATTA standard, the "maximum value" in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are regular internal pressures.

Normal load means the load specified in the standard on which the tire relies. The "maximum load capacity" in the JATTA standard, the "maximum value" in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads.

In the tire, the portion having the tread surface in contact with the road surface is the tread portion. The part that fits into the rim is the bead part. The part that connects the tread part and the bead part is the side part. The tire includes a tread portion, a pair of side portions each connected to the end of the tread portion and extending inward in the radial direction, and a pair of bead portions each located radially inside the side portion.

1 and 2 show a rigidity evaluation device 2 (hereinafter, also referred to as an evaluation device 2) used in the tire T evaluation method according to the embodiment of the present invention. FIG. 1 is a front view of the evaluation device 2, and FIG. 2 is a side view of the evaluation device 2. In FIG. 1, the left-right direction is the axial direction of the tire T, and the vertical direction is the radial direction of the tire T. In FIG. 2, the vertical direction and the horizontal direction are the radial directions of the tire T, and the direction perpendicular to the paper surface is the axial direction of the tire T.

In this evaluation method, a static tester for measuring the rigidity of the tire T is used as the evaluation device 2. The evaluation device 2 includes a support unit 4 and a measurement unit 6.

The support unit 4 includes a support shaft 8 and a base 10. The support shaft 8 supports the tire T. In the evaluation device 2, the rim R on which the tire T is assembled is attached to one end of the support shaft 8. The other end of the support shaft 8 is attached to the base 10. In the evaluation device 2, the support shaft 8 is arranged in the support unit 4 so that its axis AL extends in the axial direction.

The base 10 supports the support shaft 8. Although not shown, the base 10 includes a moving mechanism. In the support unit 4, the moving mechanism of the base 10 supports the support shaft 8 so as to be movable up and down. In this evaluation device 2, a well-known actuator is used as a moving mechanism of the base 10.

The measuring unit 6 includes a table 12 and a support portion 14. The table 12 is arranged below the tire T attached to the support shaft 8. Since the tire T is attached to the support shaft 8 via the rim R, the table 12 is located directly below the rim R. The table 12 includes a mounting surface 16 on which the tire T is placed. The mounting surface 16 is a flat surface extending in the horizontal direction. The mounting surface 16 and the axis AL of the support shaft 8 are in a parallel relationship.

The support portion 14 supports the table 12. Although not shown, the support portion 14 includes a moving mechanism. In the measuring unit 6, the moving mechanism of the support portion 14 supports the table 12 so as to be movable in the axial direction. In the evaluation device 2, for example, a well-known actuator is used as a moving mechanism of the support portion 14.

The support portion 14 includes a displacement sensor 18 and a load sensor 20. The displacement sensor 18 detects the displacement when the table 12 is moved in the axial direction. Examples of the displacement sensor 18 include an encoder. The load sensor 20 detects the load when the table 12 is moved in the axial direction. Examples of the load sensor 20 include a load cell.

The evaluation device 2 includes a control unit 22. The control unit 22 is composed of, for example, a microcomputer having a calculation unit such as a CPU, a storage unit including a RAM and a ROM, and the calculation unit executes a program stored in the storage unit to exert a predetermined function. .. In this evaluation device 2, the control unit 22 is connected to each of the support unit 4 and the measurement unit 6 by a communication cable 24. Although not described in detail, the control unit 22 controls the support unit 4 and the measurement unit 6.

Next, an evaluation method for the tire T, which is performed using the evaluation device 2 described above, will be described. This evaluation method includes an adjustment step, a contact step, and a deformation step.

In the adjustment step, the tire T is assembled to the rim R, and the internal pressure of the tire T is adjusted. In this adjustment step, air is filled inside the tire T assembled on the rim R, and the internal pressure of the tire T is adjusted. In this evaluation method, after adjusting the internal pressure, the tire T is attached to the support shaft 8 via the rim R. The internal pressure of the tire T may be adjusted after the tire T is attached to the support shaft 8 via the rim R.

In the contact process, the support shaft 8 is moved downward. As a result, the rim R attached to the support shaft 8 moves toward the table 12. As the rim R moves, the tire T assembled on the rim R moves toward the table 12, and the tire T comes into contact with the mounting surface 16 of the table 12. By bringing the rim R closer to the table 12, a vertical load is applied to the tire T. In this contact step, the rim R is moved toward the table 12 and the tire T is brought into contact with the table 12. In this contact process, a vertical load is applied to the tire T.

In the deformation step, the table 12 is moved in the axial direction. As a result, the table 12 moves in the axial direction with respect to the rim R. Since the tire T is in close contact with the table 12, the movement of the table 12 deforms the tire T. In this deformation step, the tire T is deformed by moving the table 12 in the axial direction with respect to the rim R.

As described above, in the evaluation device 2 used in this evaluation method, the displacement sensor 18 detects the displacement when the table 12 is moved in the axial direction, and the load sensor 20 moves the table 12 in the axial direction. Detect the load at the time. In this evaluation method, the displacement detected by the displacement sensor 18 represents the displacement of the tire T, and the load required to move the table 12 in the axial direction detected by the load sensor 20 is the lateral load acting on the tire T. Represent. In this evaluation method, the displacement of the tire T and the lateral load acting on the tire T are measured in this deformation step. In this evaluation method, the displacement is measured in the range of 0 mm or more and 25 mm. The lateral load is measured in the range of 0.000 kN or more and 1.50 kN or less.

In this evaluation method, the measured displacement of the tire T and the lateral load acting on the tire T are input to the control unit 22. In this control unit 22, the displacement of the tire T and the lateral load acting on the tire T are analyzed, and the rigidity of the tire T is evaluated. The control unit 22 has a function as an analysis means 26 for analyzing the displacement of the tire T and the lateral load acting on the tire T. Then, this evaluation method includes an analysis step of analyzing the displacement of the tire T and the lateral load acting on the tire T.

FIG. 3 shows an example of the analysis result obtained in the analysis step. FIG. 3 is a graph showing the relationship between the displacement of the tire T and the lateral load acting on the tire T. In this graph, the horizontal axis is the displacement of the tire T, and the vertical axis is the lateral load acting on the tire T.

As shown in FIG. 3, the lateral load increases as the displacement increases. In this evaluation method, the displacement indicating a predetermined vertical load is read from the graph, and the rigidity of the tire T is evaluated based on the vertical load and the displacement. A vertical load indicating a predetermined displacement may be read from the graph, and the rigidity of the tire T may be evaluated based on the displacement and the vertical load.

In this evaluation method, the internal pressure of the tire T is adjusted in the adjusting process. In this evaluation method, since the tire T is held in a state of being assembled on the rim R, the lateral load can be measured. By setting the internal pressure of the tire T at a low pressure, the side portion of the tire T can be deformed relatively freely without being affected by the air filled inside. In this evaluation method, the lateral load of the tire T can be measured in a state close to a state in which the inside is not filled with air.

In this evaluation method, the internal pressure of the tire T is adjusted in the adjusting step, and the internal pressure of the tire T is 100 kPa or less. In this evaluation method, since the tire T is held in a state of being assembled on the rim R, the lateral load can be measured. Since the internal pressure of the tire T is set at a low pressure, the side portion of the tire T can be deformed relatively freely without being affected by the air filled inside. In this evaluation method, the lateral load of the tire T can be measured in a state close to a state in which the inside is not filled with air.

In this evaluation method, a vertical load is applied to the tire T in the contact process. In this evaluation method, the tread surface of the tire T is pressed against the table 12. Since the tire T is prevented from slipping on the table 12, the lateral load can be measured. In this evaluation method, the vertical load is set to a low load, so that the deformation of the tire T due to the vertical load is suppressed. In this evaluation method, the lateral load of the tire T is measured in a state close to a state in which no vertical load is applied to the tire T.

In this evaluation method, a vertical load is applied to the tire T in the contact process, and the vertical load is 1.5 kN or less. In this evaluation method, the tread surface of the tire T is pressed against the table 12. Since the tire T is prevented from slipping on the table 12, the lateral load can be measured. In this evaluation method, since the vertical load is set at a low load, the deformation of the tire T due to this vertical load is suppressed. In this evaluation method, the lateral load of the tire T is measured in a state close to a state in which no vertical load is applied to the tire T.

When the tire T is assembled to the rim R, the inside of the tire T is not filled with air. No vertical load is applied to this tire T. As described above, in this evaluation method, the internal pressure of the tire T is set at a low pressure, and the vertical load applied to the tire T is set at a low load. Specifically, the internal pressure of the tire T is set to 100 kPa or less, and the vertical load applied to the tire T is set to 1.5 kN or less. As a result, in this evaluation method, the lateral load of the tire T is measured in a state close to a state in which the inside is not filled with air and in a state close to a state in which no vertical load is applied to the tire T. The state of the tire T reproduced by this evaluation method is close to the state of the tire T assembled on the rim R.

In this evaluation method, the rigidity of the side portion can be grasped in consideration of the state of the tire T assembled on the rim R. This evaluation method can quantitatively evaluate the ease of assembling with the rim R.

In this evaluation method, the internal pressure of the tire T is preferably 25 kPa or more, and preferably 75 kPa or less.

When the internal pressure of the tire T is set to 25 kPa or more, the bead portion of the tire T is sufficiently pressed against the flange of the rim R. In this evaluation method, the tire T is sufficiently held by the rim R, so that the lateral load is stably measured.

By setting the internal pressure of the tire T to 75 kPa or less, the influence of the air filled inside on the deformation of the side portion of the tire T can be effectively suppressed. In this evaluation method, the lateral load of the tire T is measured in a state closer to the state in which the inside is not filled with air. From this viewpoint, the internal pressure of the tire T is more preferably 50 kPa or less.

In this evaluation method, the vertical load applied to the tire T is preferably 0.75 kN or more, and preferably 1.25 kN or less.

When the vertical load is set to 0.75 kN or more, the tread surface of the tire T is sufficiently pressed against the table 12. Since the slip of the tire T with respect to the table 12 is effectively prevented, the lateral load is stably measured.

By setting the vertical load to 1.25 kN or less, the deformation of the tire T due to this vertical load is effectively suppressed. In this evaluation method, the lateral load of the tire T is measured in a state closer to the state in which the vertical load is not applied to the tire T. From this viewpoint, the vertical load is more preferably 1.00 kN or less.

The table 12 provided in the measurement unit 6 of the evaluation device 2 used in this evaluation method is formed of a flat surface and includes a mounting surface 16 that comes into contact with the tire T. In this evaluation method, the area of the mounting surface 16 is larger than the area of the contact surface formed by the tire T coming into contact with the mounting surface 16. In this evaluation method, since the contact surface between the tire T and the table 12 is formed without excess or deficiency, slippage of the tire T with respect to the table 12 is more effectively prevented. In this evaluation method, the lateral load of the tire T is measured more stably even though the internal pressure of the tire T is set at a low pressure and the vertical load applied to the tire T is set at a low load. From this point of view, in this evaluation method, in this evaluation method, the table 12 provided in the measuring unit 6 is formed of a flat surface and includes a mounting surface 16 that comes into contact with the tire T, and the area of the mounting surface 16 is such that the tire T is mounted. It is preferable that the evaluation device 2 is configured so as to be larger than the area of the contact surface formed by contacting with the placement surface 16.

As is clear from the above description, in the evaluation method of the tire T of the present invention, the rigidity of the side portion can be grasped in consideration of the state of the tire T assembled on the rim R. This evaluation method can quantitatively evaluate the ease of assembling with the rim R.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the present invention is not limited to such Examples.

[Tire preparation]
Three types of tires (size = 195 / 85R16) with different ease of assembly with the rim were prepared. These three types of tires were selected based on the sensory evaluation results regarding the ease of assembly with the rim by the operator. Table 1 below shows this result. The higher the score, the easier it is to assemble on the rim. As shown in Table 1, among the tires A, B and C, the tire A is the easiest to assemble on the rim, and the tire C is the most difficult to assemble on the rim. Tire B is harder to assemble on the rim than tire A and easier to assemble on the rim than tire C.

[Example 1]
The rigidity of three types of tires was evaluated using the evaluation device having the basic configuration shown in FIGS. 1 and 2. As shown in Table 2 below, the internal pressure of the tire was set to 50 kPa and the load applied to the tire was set to 1.00 kN.

In the graph showing the relationship between the displacement and the lateral load, the displacement (unit: mm) when the lateral load is 0.5 kN is read, and the ratio of the lateral load (that is, 0.5 kN) to this displacement is defined as the rigidity of the tire. did. Table 2 below shows the rigidity of each tire as an index with tire B as 100. The larger the value, the higher the rigidity of the tire and the less easily the side part is deformed.

[Example 2-4 and Comparative Example 1]
The rigidity of the three types of tires was evaluated in the same manner as in Example 1 except that the internal pressure of the tires was set as shown in Table 2 below. The results are shown in Table 2 below. Comparative Example 1 represents a state in which the internal pressure is not adjusted.

[Example 5-7 and Comparative Example 2]
The rigidity of the three types of tires was evaluated in the same manner as in Example 1 except that the vertical load applied to the tires was as shown in Table 3 below. The results are shown in Table 3 below. In Comparative Example 2, the tire was in contact with the table, but the vertical load could not be measured. This Comparative Example 2 corresponds to a state in which no vertical load is applied.

As shown in Tables 2 and 3, it has been confirmed that in the examples, the rigidity evaluation results reflecting the sensory evaluation results shown in Table 1 can be obtained. From this evaluation result, the superiority of the present invention is clear. In Comparative Example 1, the tire was not stably held by the rim, and the lateral load could not be measured stably. In Comparative Example 2, the tire slipped against the table, and the lateral load could not be measured stably.

The technique for evaluating tire rigidity described above can also be applied to various tire evaluation methods.

2 ... Rigidity evaluation device 4 ... Support unit 6 ... Measurement unit 8 ... Support shaft 10 ... Base 12 ... Table 14 ... Support 16 ... Mounting surface 18・ ・ ・ Displacement sensor 20 ・ ・ ・ Load sensor 22 ・ ・ ・ Control unit 24 ・ ・ ・ Communication cable 26 ・ ・ ・ Analysis means

Claims (5)

The process of assembling the tire to the rim and adjusting the internal pressure of the tire,
A step of moving the rim toward a table located directly below the rim and bringing the tire into contact with the table.
Including a step of moving the table in the axial direction of the tire with respect to the rim to deform the tire.
In the contact process, a vertical load is applied to the tire,
In the deformation step, the displacement of the tire and the lateral load acting on the tire are measured.
The internal pressure of the tire is 100 kPa or less,
A tire evaluation method in which the vertical load is 1.5 kN or less. The method for evaluating a tire according to claim 1, wherein the internal pressure of the tire is 25 kPa or more and 75 kPa or less. The method for evaluating a tire according to claim 1 or 2, wherein the longitudinal load is 0.75 kN or more and 1.25 kN or less. The table comprises a mounting surface that is flat and in contact with the tire.
The method for evaluating a tire according to any one of claims 1 to 3, wherein the area of the above-mentioned mounting surface is larger than the area of the contact surface formed by the tire coming into contact with the above-mentioned mounting surface. The process of assembling the tire to the rim and adjusting the internal pressure of the tire,
A step of moving the rim toward a table located directly below the rim and bringing the tire into contact with the table.
Including a step of moving the table in the axial direction of the tire with respect to the rim to deform the tire.
In the contact process, a vertical load is applied to the tire,
A tire evaluation method in which the displacement of the tire and the lateral load acting on the tire are measured in the deformation step.

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