METHOD OF TESTING RUBBER WEAR, AND METHOD, DEVICE AND PROGRAM OF CALCULATING RUBBER INDEX OF TIRE USING METHOD OF TESTING RUBBER WEAR

• US 20130036791A1
• Filed: 02/24/2011
• Published: 02/14/2013
• Est. Priority Date: 02/24/2010
• Status: Active Grant

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Shibata, Tomonori
• Granted Patent: US 9,052,257 B2
• Time in Patent Office: Days
• US Class Current: 73/8
• CPC Class Codes: G01M 17/022 the tyre co-operating with rotatable rolls
• CPC Class Codes: G01N 2203/0218 Calculations based on experimental data
• CPC Class Codes: G01N 3/56 Investigating resistance to wear or abrasion

Abstract

Provided is a method of testing rubber wear in which a wear phenomenon occurred in a tire can be precisely reproduced in a sample, and a method of calculating the rubber index of a tire using the method of testing rubber wear.

Also provided is a test method for predicting the anti-wear properties of a tire by using a test piece of the same rubber as that of a tire tread, which is a method of testing rubber wear in which, while a disk-shaped sample 3 and a disk-shaped grinding wheel 1 are rotated at individually predetermined numbers of rotations, the sample 3 is pressed on the outer periphery of the grinding wheel 1. A pressing load is applied to the sample 3 such that a contact pressure when the sample is pressed on the outer periphery of the grinding wheel 1 and a contact pressure at a site related to the evaluation of rubber wear of tread are the same.

Claims

1. A method of testing rubber wear by predicting the anti-wear properties of a tire with the use of a test piece of the same rubber as that of a tire tread, in which, while a disk-shaped sample and a disk-shaped grinding wheel are rotated at individually predetermined numbers of rotations, the sample is pressed on the outer periphery of the grinding wheel, wherein

a pressing load is applied to the sample such that a contact pressure when the sample is pressed on the outer periphery of the grinding wheel and a contact pressure at a site related to the evaluation of rubber wear of a contact patch portion of the tire are the same.

2. The method of testing rubber wear according to claim 1, wherein a torque is applied to the disk-shaped sample such that a frictional energy generated when the disk-shaped sample is pressed on the outer periphery of the grinding wheel in a state in which the pressing load is applied and a frictional energy at a site related to the evaluation of rubber wear of a contact patch portion of the tire are the same.

3. A rubber index calculating method of a tire comprising

a tire frictional energy measurement step in which a tire frictional energy of a tire under plural tire input conditions which are provided to the tire is measured by a frictional energy measurement device which performs measurement based on the shearing force and the slippage of a tire contact patch,

a contact pressure measurement step in which a contact pressure at a site related to the evaluation of rubber wear of the contact patch portion of the tire is measured,

a pressing load setting step in which setting is performed such that the contact pressure is applied to a sample as a pressing load,

a setting step in which the sample frictional energy of a sample of the same material as that of the tire is determined under sample input conditions set based on the tire frictional energy under each of the measured tire input conditions in a state in which the pressing load is applied to the sample, and a measurement condition for measuring the sample wear amount of the sample is set based on the tire frictional energy under each of the measured tire input conditions and the sample frictional energy determined under each of the sample input conditions,

a sample wear amount measurement step in which the sample wear amount of the sample is measured by a wear amount measurement device under the set measurement condition and

a rubber index calculation step in which the rubber index of the tire is calculated based on the measured sample frictional energy and the sample wear amount.

4. The rubber index calculating method of a tire according to claim 3, wherein

the setting step comprises

a step in which a frictional energy function representing the correspondence relationships between the tire input condition and the tire frictional energy is calculated for each of the types of the tire input conditions,

a step in which an expected value of the tire frictional energy is calculated based on the frequency data representing the relationship between the tire input measured during practical vehicle travel using the tire and the frequency of the tire input, and on the frictional energy function for each of the tire input conditions,

a sample input condition setting step which sets sample input conditions which are provided to the sample for measuring the sample frictional energy of the sample by the frictional energy measurement device,

a sample frictional energy measurement step in which the sample frictional energy of the sample is measured under the set sample input conditions, and the sample frictional energy is measured while changing the sample input conditions until the measured sample frictional energy corresponds to the expected value of the tire frictional energy and

a sample wear amount measurement condition setting step in which the measured sample frictional energy sets a sample input condition corresponding to the expected value of the tire frictional energy as a measurement condition for measuring the sample wear amount,

wherein, in the sample wear amount measurement step, the sample wear amount of the sample is measured under a measurement condition set in the sample wear amount measurement condition setting step.

5. The rubber index calculating method of a tire according to claim 3, wherein

the setting step comprises,

for each of the plural tire input conditions,

a sample input condition setting step which sets sample input conditions which are provided to the sample for measuring the sample frictional energy of the sample by the frictional energy measurement device,

a sample frictional energy measurement step in which the sample frictional energy of the sample is measured under the set sample input conditions, and the sample frictional energy is measured while changing the sample input conditions until the measured sample frictional energy corresponds to the tire frictional energy measured by the corresponding tire input condition and

a sample wear amount measurement condition setting step in which the measured sample frictional energy sets a sample input condition corresponding to the tire frictional energy measured under the corresponding tire input condition as a measurement condition for measuring the sample wear amount,

wherein, for each of the plural tire input conditions, in the sample wear amount measurement step, the sample wear amount of the sample is measured under a measurement condition set in the sample wear amount measurement condition setting step, and

the rubber index calculation step comprises,

for each of the plural tire input conditions, a step of calculating rubber index based on the frictional energy and the sample wear amount,

a step of calculating for each of the types of the tire input conditions, the rubber index function representing the correspondence relationships between the tire input condition and the tire rubber index based on the rubber index calculated for each of the plural tire input conditions and

a step of calculating the expected value of the rubber index based on frequency data representing the relationship between the tire input measured during practical vehicle travel using the tire and frequency of the tire input, and on rubber index function for each of the tire input conditions.

6. The rubber index calculating method of a tire according to claim 3, wherein

the setting step comprises

a step in which a frictional energy function representing the correspondence relationships between the tire input condition and the tire frictional energy is calculated for each of the types of the tire input conditions,

a step in which an expected value of the tire frictional energy is calculated based on the frequency data representing the relationship between the tire input measured during practical vehicle travel using the tire and the frequency of the tire input, and on the frictional energy function for each of the tire input conditions,

a sample input condition setting step which sets sample input conditions which are provided to the sample for computing the sample frictional energy of the sample by a sample model of the sample,

a sample frictional energy computing step in which the sample frictional energy of the sample is computed under the set sample input conditions, and the sample frictional energy is computed while changing the sample input conditions until the computed sample frictional energy corresponds to the expected value of the tire frictional energy and

a sample wear amount measurement condition setting step in which the computed sample frictional energy sets a sample input condition corresponding to the expected value of the tire frictional energy as a measurement condition for measuring the sample wear amount,

wherein, in the sample wear amount measurement step, the sample wear amount of the sample is measured under a measurement condition set in the sample wear amount measurement condition setting step.

7. The rubber index calculating method of a tire according to claim 3, wherein

the setting step comprises,

for each of the plural tire input conditions,

a sample input condition setting step which sets sample input conditions which are provided to the sample for computing the sample frictional energy of the sample based on the sample model of the sample,

a sample frictional energy computing step in which the sample frictional energy of the sample is computed under the set sample input conditions, and the sample frictional energy is computed while changing the sample input conditions until the computed sample frictional energy corresponds to the tire frictional energy measured by the corresponding tire input condition and

a sample wear amount measurement condition setting step in which the measured sample frictional energy sets a sample input condition corresponding to the tire frictional energy measured under the corresponding tire input condition as a measurement condition for measuring the sample wear amount,

wherein, for each of the plural tire input conditions, in the sample wear amount measurement step, the sample wear amount of the sample is measured under a measurement condition set in the sample wear amount measurement condition setting step, and

the rubber index calculation step comprises,

for each of the plural tire input conditions, a step of calculating rubber index based on the frictional energy and the sample wear amount,

a step of calculating for each of the types of the tire input conditions, the rubber index function representing the correspondence relationships between the tire input condition and the tire rubber index based on the rubber index calculated for each of the plural tire input conditions and

a step of calculating the expected value of the rubber index based on frequency data representing the relationship between the tire input measured during practical vehicle travel using the tire and frequency of the tire input, and on rubber index function for each of the tire input conditions.

8. A rubber index calculation device of a tire comprising

a tire frictional energy measurement means in which a tire frictional energy of a tire under plural tire input conditions which are provided to the tire is measured by a frictional energy measurement device which performs measurement based on the shearing force and the slippage of a tire contact patch,

a contact pressure measurement means in which a contact pressure at a site related to the evaluation of rubber wear of the contact patch portion of the tire is measured,

a pressing load setting means in which setting is performed such that the contact pressure is applied to a sample as a pressing load,

a setting means in which the sample frictional energy of a sample of the same material as that of the tire is determined under sample input conditions set based on the tire frictional energy under each of the measured tire input conditions in a state in which the pressing load is applied to the sample, and a measurement condition for measuring the sample wear amount of the sample is set based on the tire frictional energy under each of the measured tire input conditions and the sample frictional energy determined under each of the sample input conditions,

a sample wear amount measurement means in which the sample wear amount of the sample is measured by a wear amount measurement device under the set measurement condition and

a rubber index calculation means in which the rubber index of the tire is calculated based on the measured sample frictional energy and the sample wear amount.

9. A tire rubber index calculation program wherein the program allows a computer to execute a processing comprising

a tire frictional energy measurement step in which a tire frictional energy of a tire under plural tire input conditions which are provided to the tire is measured by a frictional energy measurement device which performs measurement based on the shearing force and the slippage of a tire contact patch,

a contact pressure measurement step in which a contact pressure at a site related to the evaluation of rubber wear of the contact patch portion of the tire is measured,

a pressing load setting step in which setting is performed such that the contact pressure is applied to a sample as a pressing load,

a setting step in which the sample frictional energy of a sample of the same material as that of the tire is determined under sample input conditions set based on the tire frictional energy under each of the measured tire input conditions in a state in which the pressing load is applied to the sample, and a measurement condition for measuring the sample wear amount of the sample is set based on the tire frictional energy under each of the measured tire input conditions and the sample frictional energy determined under each of the sample input conditions,

a sample wear amount measurement step in which the sample wear amount of the sample is measured by a wear amount measurement device under the set measurement condition and

a rubber index calculation step in which the rubber index of the tire is calculated based on the measured sample frictional energy and the sample wear amount.