Method for evaluating carcass durability of bead portion of heavy-duty tire

Abstract

A method for evaluating carcass durability of a bead portion of a heavy-duty tire includes a running step of running a test tire on a drum, and an evaluation step of evaluating the carcass durability of the bead portion. In the running process, the internal pressure P is 160-260% of the normal internal pressure P0, the load F is 350-450% of the normal load F0, the running speed V is 15-40km / h, and the test tire is set at a specified flexure. driving in a curved state. The deflected state is when the angle of the reference line X passing through the innermost point in the tire axial direction of the bead core and the point of the maximum width in the tire axial direction of the carcass ply relative to the tire axial direction line is θ, in normal A deflected state in which a difference (θ0−θ1) between the value θ0 of the angle θ of the tire in the internal pressure state and the value θ1 of the angle θ of the tire in the running process is in the range of 5° to 15°. Thereby, the carcass durability can be evaluated with high accuracy in a short test time.

Description

technical field [0001] The present invention relates to a heavy-duty tire capable of reproducing damage to carcass cords caused by friction with bead cores in a short test time and capable of evaluating carcass durability with high accuracy in a short test time Method for evaluating carcass durability of bead portion. Background technique [0002] Such as Image 6 As shown, a bead core b is arranged on the bead portion a of the heavy-duty tire. The bead core b is formed by winding steel wires in multiple rows and segments, and its cross section is polygonal, usually hexagonal. In addition, both end portions of the carcass ply c constituting the frame of the tire are locked by being folded around the bead core b. [0003] However, since the heavy-duty tire is used under severe conditions of high internal pressure and high load, a large tension f acts on the carcass cords of the carcass ply c. As a result, so-called fretting occurs on the carcass cord. rub against each othe...

AI Technical Summary

Problems solved by technology

In addition, there is a problem that the continuation of the wear caused by the fretting wear causes the strong force of the carcass cord to decrease, and eventually the cord breaks and even the tire blows out.

However, there is no effective test method that reproduces the fretting wear of the bead portion in a short test time to accurately evaluate the durability of the carcass in a short test time, and the emergence of such a test method is strongly demanded.

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