JP2006300725A - Method of testing tire wear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of testing tire wear which can accurately evaluate wear characteristics in actual driving. <P>SOLUTION: The method performs a pretreatment process for providing a pneumatic tire with outer-diameter growth and performs an indoor wear test process on the pneumatic tire which has passed through the pretreatment process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a test method for evaluating the wear characteristics of a pneumatic tire, and more particularly to a tire wear test method that makes it possible to more accurately evaluate the wear characteristics in actual driving.

  Conventionally, when evaluating the wear characteristics of a pneumatic tire, a new pneumatic tire is mounted on a drum-type indoor wear tester, and a wear test is performed while the pneumatic tire is running on a drum (for example, , See Patent Document 1). Therefore, what is obtained by the conventional tire wear test method is wear characteristics based on a new tire structure.

On the other hand, in a pneumatic tire subjected to actual traveling, outer diameter growth and changes in physical properties of rubber occur with a long-term traveling from a new state. Therefore, the wear characteristics obtained by the conventional tire wear test method do not necessarily accurately reflect the wear characteristics in actual running. Accordingly, there is a need for a tire wear test method that takes into account changes in the tire structure during actual driving.
JP 2004-53482 A

  An object of the present invention is to provide a tire wear test method that makes it possible to more accurately evaluate the wear characteristics in actual driving.

  In order to achieve the above object, the tire wear test method of the present invention includes a pretreatment step for causing an outer diameter growth in a pneumatic tire, and an indoor wear test step for the pneumatic tire that has undergone the pretreatment step. It is characterized by carrying out.

  In the present invention, prior to the indoor wear test step, a pretreatment step for causing the outer diameter growth of the pneumatic tire is performed. In this pretreatment process, the outer diameter growth in actual running is reproduced. Then, in the indoor wear test process, the wear amount and the uneven wear mode are evaluated for the pneumatic tire in a state where the outer diameter has grown. This makes it possible to more accurately evaluate the wear characteristics in actual driving.

  As the pretreatment step, various treatments can be selected as long as they cause sufficient outer diameter growth in the pneumatic tire. For example, in the pretreatment step, the rim-assembled pneumatic tire is inflated to a normal internal pressure or higher and left in an environment of 50 ° C. or higher for 24 hours or longer. In this case, the outer diameter growth is reproduced by leaving it dry. In the pretreatment step, the rim-assembled pneumatic tire is inflated to a normal internal pressure or more and continuously run for 10 hours or more. In this case, the outer diameter growth based on the calorific value specific to the tire can be reproduced. Furthermore, in the pre-treatment process, it is also possible to inflate the rim-assembled pneumatic tire above the normal internal pressure and leave it in an environment of 50 ° C. or more for 24 hours or more, and further run continuously for 10 hours or more. is there.

  Although the load condition and speed condition in the pretreatment process and the indoor wear test process can be arbitrarily set, the load (MN) on the tire and the running speed (km / h) of the tire in the pretreatment process are determined. The operation MNKPH value in the pretreatment process calculated from the product is set to be equal to or greater than the operation MNKPH value in the indoor wear test process calculated from the product of the load on the tire and the running speed of the tire in the indoor wear test process. preferable. The outer diameter growth of the pneumatic tire is determined by the operation MNKPH value. If the operation MNKPH value in the pretreatment process is made larger than the operation MNKPH value in the indoor wear test process, sufficient outer diameter growth is achieved in the pretreatment process. Obtainable.

  In at least one of the pretreatment step and the indoor wear test step, the oxygen concentration of the gas filled in the pneumatic tire is preferably 30% or more. As described above, by increasing the oxygen concentration of the gas filled in the pneumatic tire, it is possible to evaluate the wear characteristics in a state in which characteristic changes due to rubber deterioration are taken into account.

  In the indoor wear test process, it is preferable to impart at least one of a slip angle and a camber angle to the pneumatic tire. That is, in the indoor wear test process, the slip angle may be set to other than 0 °, the camber angle may be set to other than 0 °, or both the slip angle and the camber angle may be set to other than 0 °. Thereby, the wear characteristics according to the alignment conditions can be evaluated.

  In the indoor wear test process, a pneumatic tire is run with a load and a strip angle applied, and a lateral force generated in the tire rotation axis direction during running is detected, and the lateral force is controlled to a desired value. It is preferable to maintain the running state. In the indoor wear test process, by maintaining the running state while controlling the lateral force to a desired value, it is possible to evaluate the wear characteristics under the condition that makes the running environment severe.

  Furthermore, in the indoor wear test process, it is preferable to affix abrasive paper on the traveling road surface of the pneumatic tire. Thereby, while reproducing an actual road surface, evaluation in a short time is attained by accelerating wear.

  Further, in the indoor wear test process, it is preferable to roll the sticky rotating body on the traveling road surface of the pneumatic tire. In this case, since the rotating body having adhesiveness removes wrinkles of the tread rubber adhering to the traveling road surface, the wear characteristics can be more accurately evaluated.

  In the tire wear test method of the present invention, prior to the indoor wear test process, a pretreatment process for causing the outer diameter growth of the pneumatic tire is performed. Any of the following three processes may be selected as the pretreatment process.

  The first pretreatment step is to inflate the rim-assembled pneumatic tire to a normal internal pressure or higher and leave it in an environment of 50 ° C. or higher for 24 hours or longer. In this case, when the heating temperature is less than 50 ° C. or the heating time is less than 24 hours, the outer diameter growth based on heating becomes insufficient. However, it is desirable that the upper limit value of the heating temperature is 100 ° C. and the upper limit value of the heating time is 720 hours. The normal internal pressure is an internal pressure when a pneumatic tire is normally used, but a constant internal pressure may be adopted for tires of the same size.

  The second pretreatment step is to inflate the rim-assembled pneumatic tire to a normal internal pressure or more and perform continuous running for 10 hours or more. In this case, if the running time is less than 10 hours, the outer diameter growth based on the calorific value inherent to the tire becomes insufficient. However, the upper limit of the travel time is preferably 720 hours. The normal internal pressure is an internal pressure when a pneumatic tire is normally used, but a constant internal pressure may be adopted for tires of the same size. The load on the tire may be 80 to 150% of the load specified by JATMA, and the running speed of the tire may be 30 to 200 km / h.

  The third pretreatment step is to inflate the rim-assembled pneumatic tire above the normal internal pressure, leave it in an environment of 50 ° C. or higher for 24 hours or more, and perform continuous running for 10 hours or more. . That is, the first and second pretreatment steps can be combined.

  On the other hand, in the indoor wear test process, a pneumatic tire is run on the drum using a drum type indoor wear tester or the like to evaluate the wear characteristics, but when the pretreatment process is performed under the above-described conditions, Since the outer diameter grows in the pneumatic tire, the wear characteristics in actual running can be more accurately evaluated in the indoor wear test process. The evaluation items for the wear characteristics include the amount of wear and the form of uneven wear. For example, it is included in the evaluation of the wear characteristics to check whether shoulder wear or center wear has occurred under specific driving conditions.

  The operation MNKPH value in the indoor wear test process calculated from the product of the load on the tire and the running speed of the tire in the indoor wear test process is calculated from the product of the load on the tire and the running speed of the tire in the pretreatment process. The same as or lower than the operation MNKPH value in the preprocessing step to be performed. Thereby, in the indoor wear test process, the outer diameter growth of the pneumatic tire is substantially not generated, and the wear characteristics can be evaluated in a state where the outer diameter growth is saturated.

  In the pretreatment process and the indoor wear test process described above, air can be used as a gas to be filled in the pneumatic tire. However, in at least one of the two processes, the oxygen concentration of the gas to be filled in the pneumatic tire is used. Should be 30% or more. By increasing the oxygen concentration of the gas filled in the pneumatic tire, it is possible to evaluate the wear characteristics in a state in which a characteristic change due to rubber deterioration (for example, an increase in the modulus of the cap tread rubber) is taken into account. In addition, the wear of the rubber is accelerated by oxygen, which is an accelerated test. The oxygen concentration referred to here is a volume fraction, and can be obtained from, for example, the partial pressure of oxygen with respect to the total pressure of gas. When the oxygen concentration is less than 30%, the promotion of oxidative deterioration becomes insufficient.

  In the indoor wear test process, it is preferable to impart at least one of a slip angle and a camber angle to the pneumatic tire. The slip angle is preferably set in the range of −3 ° to + 3 °, and the camber angle is preferably set in the range of −3 ° to +3.

  In addition to these slip angle and camber angle, it is necessary to apply a load to the pneumatic tire. When the wear characteristics of a plurality of types of pneumatic tires are evaluated under the same slip angle, the lateral force generated during traveling differs depending on the tire characteristics. For example, when the cornering power differs between tires, even if the slip angle is the same, a tire having a large cornering power has a greater lateral force in the tire rotation axis direction, which is disadvantageous in evaluating wear characteristics. On the other hand, in actual running, tires having any characteristics receive the same lateral force when running on the same course at the same speed. In other words, when the wear characteristics are evaluated under the same slip angle, the lateral force applied to the tire differs depending on the tire characteristics, and the wear characteristics in actual running may not be accurately reflected.

  Therefore, when the pneumatic tire is run with a load and a strip angle applied, the following control may be performed. That is, in the indoor wear test process, the pneumatic tire is run with a load and a strip angle applied, and the lateral force generated in the tire rotation axis direction during running is detected, and the lateral force is controlled to a desired value. The running state is maintained.

  Here, consider a tire A having a relatively high cornering power and a tire B having a relatively low cornering power. As shown in FIG. 1, in the slalom test in which the slip angle SA (amplitude) is periodically changed, when the slip angles SA of the tires A and B running on the rotary drum 1 are the same, the tire rotation axis during running The lateral force SF generated in the direction is greater in the tire A than in the tire B. That is, the tire A is exposed to a severer driving environment. On the other hand, as shown in FIG. 2, in the slalom test in which the slip angle SA (amplitude) is periodically changed, the slip angle SA of the tires A and B running on the rotary drum 1 is optimized and the vehicle is running. When the lateral force SF generated in the tire rotation axis direction is the same, the wear characteristics can be evaluated under the same conditions as the driving environment. As a result, the wear characteristics in actual traveling can be more accurately evaluated.

  In the indoor wear test process, abrasive paper can be attached to the running road surface of the pneumatic tire. The roughness of the abrasive paper is not particularly limited, but by selecting an appropriate roughness, it is possible to reproduce the actual road surface, accelerate wear, and evaluate in a short time.

  Further, in the indoor wear test process, the rotating body having adhesiveness can be rolled on the traveling road surface of the pneumatic tire. For example, in FIG. 3, in an indoor wear tester in which tires A and B are caused to travel with respect to the rotating drum 1, the rotating body 2 having adhesiveness is installed so as to roll on the outer peripheral surface of the rotating drum 1. Has been. The outer diameter of the rotating body 2 is smaller than the outer diameter of the rotating drum 1. Therefore, the rotating speed of the rotating body 2 is higher than the rotating speed of the rotating drum 1. As the rotating body 2, a rubber roller, a tire, or the like can be used. The outer peripheral part of the rotary body 2 is comprised from the rubber composition whose tan-delta in 20 degreeC is 0.6-1.0, for example.

  When the tires A and B are continuously run for a long time, the tread rubber heels adhere to the running road surface of the tires A and B. However, when the rotating body 2 is attached to the rotating drum 1, Since the body 2 removes the tread rubber wrinkles adhering to the traveling road surface, the wear characteristics can be more accurately evaluated. The tread rubber stick attached to the rotating body 2 is released from the rotating body 2 by the centrifugal force accompanying the high-speed rotation. Therefore, as shown in FIG. 3, the rotating body 2 is made of a box or the like so that the rubber bag released from the rotating body 2 does not scatter around the indoor wear tester or adhere to the tires A and B again. It is good to arrange in the dust collector 3.

  In addition, this invention prescribes | regulates the process of a tire abrasion test method, and the structure of the test apparatus is not specifically limited.

  Two types of heavy-duty pneumatic tires (A, B) with a tire size of 11R22.5 and different reinforcement structures are produced, and a part of each tire is used on a truck while the rest is drums. This was subjected to an indoor wear test using a type of wear tester. In these actual running and indoor wear tests, the rim size was 7.50 × 22.5 and the internal pressure was 700 kPa.

  For tires that were actually mounted on trucks, the wear situation was investigated at the end of their service life. As a result, the tire A tends to cause shoulder wear, and the tire B tends to cause center wear.

On the other hand, the test conditions of the tires subjected to the indoor wear test were varied. In the conventional example, only the indoor wear test was performed. In Example 1, prior to the indoor wear test, a pneumatic tire was filled with a gas having an oxygen concentration of 30% and left to stand for 24 hours while being heated to 70 ° C. In Example 2, prior to the indoor wear test, the pneumatic tire was filled with a gas having an oxygen concentration of 30%, and was continuously run for 10 hours. Through such an indoor wear test, the wear situation of tires A and B was investigated. The results are shown in Table 1.

  As can be seen from Table 1, although the partial wear was not confirmed in the conventional example, in Examples 1 and 2, the results consistent with the wear characteristics obtained in actual running were obtained.

In a slalom test, it is a side view which shows the case where the slip angle SA of the tire which drive | works on a rotating drum is made the same. In a slalom test, it is a side view which shows the case where the slip angle SA of the tire which drive | works on a rotating drum is optimized, and the lateral force SF which arises in a tire rotating shaft direction during driving | running | working is made the same. It is a side view which shows roughly an example of the drum-type indoor abrasion tester used by this invention.

Explanation of symbols

1 Rotating drum 2 Rotating body 3 Dust collector A, B Tire

Claims (10)

  A tire wear test method, comprising: performing a pretreatment step for causing an outer diameter growth of a pneumatic tire, and performing an indoor wear test step on the pneumatic tire that has undergone the pretreatment step.   2. The tire wear test method according to claim 1, wherein in the pretreatment step, the rim-assembled pneumatic tire is inflated to a normal internal pressure or more and left in an environment of 50 ° C. or more for 24 hours or more.   2. The tire wear test method according to claim 1, wherein in the pretreatment step, the rim-assembled pneumatic tire is inflated to a normal internal pressure or more and continuously run for 10 hours or more.   In the pretreatment step, the rim-assembled pneumatic tire is inflated to a normal internal pressure or more, and left in an environment of 50 ° C. or more for 24 hours or more, and is further continuously run for 10 hours or more. Item 2. The tire wear test method according to Item 1.   The operation MNKPH value in the pretreatment step calculated from the product of the tire load and tire running speed in the pretreatment step is calculated from the product of the tire load and tire running speed in the indoor wear test step. 5. The tire wear test method according to claim 3, wherein an operation MNKPH value in the indoor wear test process is set to be equal to or higher than an operation MNKPH value.   The tire wear test method according to any one of claims 1 to 5, wherein in at least one of the pretreatment step and the indoor wear test step, the oxygen concentration of the gas filled in the pneumatic tire is set to 30% or more.   The tire wear test method according to any one of claims 1 to 6, wherein in the indoor wear test step, at least one of a slip angle and a camber angle is imparted to the pneumatic tire.   In the indoor wear test process, the pneumatic tire is run with a load and a strip angle applied, the lateral force generated in the tire rotation axis direction is detected during running, and the running state is controlled while controlling the lateral force to a desired value. The tire wear test method according to claim 1, wherein the tire wear test method is maintained.   The tire wear test method according to any one of claims 1 to 8, wherein in the indoor wear test step, abrasive paper is affixed to a running road surface of the pneumatic tire. The tire wear test method according to any one of claims 1 to 9, wherein, in the indoor wear test process, the rotating body having adhesiveness is rolled on the running road surface of the pneumatic tire.

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