Bead durability evaluation method for heavy duty tires

Abstract

A rire bead durability evaluation method for a heavy duty tire comprises: a travelling step for test tires traveling on a cylinder; and an evaluation step for evaluating travel distance or travel time of producing damage as the tire bead durability. In the travelling step, an internal pressure P is 160-260% of a standard internal pressure (P0), a load (F) is 350-450% of a standard load (F0), a traveling speed V is 15-40 km / h, and the tire section height H of a tire in the pressing test is of more than 87.5% of the tire section height (H0) in the standard internal pressure-normal load state. In the evaluation step, when the elongation of exposed surface curve length of the tire lining rubber before and after the travelling is over 115%, the durability of the tire bead is not evaluated. By using the present invention, the durability of the tire bead can be accurately evaluated with a short test time.

Description

technical field [0001] The present invention relates to a method for evaluating the bead durability of a heavy-duty tire that can accurately evaluate the bead durability of a heavy-duty tire within a short test time. Background technique [0002] Heavy-duty tires are used under severe conditions where the air pressure is high and the load is large. Hence the question: if Figure 6 As shown in (A), ply end peeling occurs starting from the turn-up end ae of the carcass ply a constituting the tire frame, and the bead portion b is damaged. [0003] Specifically, in a heavy-duty tire, since the internal pressure is high, a large tension acts on the main body portion a1 of the carcass layer a spanning between the bead cores c, c. Therefore, the turn-up portion a2 of the carcass layer a is forcibly stretched toward the bead core c side, and as a result, the turn-up end ae is deformed in the pulling direction corresponding to the surrounding rubber. [0004] In addition, in heavy ...

AI Technical Summary

Problems solved by technology

Hence the question: if Image 6 As shown in (A), ply end peeling occurs starting from the turn-up end ae of the carcass ply a constituting the tire frame, and the bead portion b is damaged

Therefore, it becomes an unbalanced test in which the deformation in the piercing direction at the turn-up end ae becomes too large compared to the deformation in the stretching direction, and there is a possibility that the structural bead produced in actual use cannot be realized. problem of adequate reproduction of damage

In addition, there are also problems in that the accuracy of durability evaluation such as errors in travel distance and travel time is poor, and the time required for the test is long.

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