METHOD OF DETERMINING PRODUCT FAILURE OF INNER SURFACE OF TIRE

PROBLEM TO BE SOLVED: To provide a method of determining a product failure of the inner surface of a tire by contriving an aspect of confining water and hydraulic pressure within a vulcanization bladder in the latter half of a vulcanization molding process, thereby accurately detecting the occurrence of a pinhole-like small hole (≤1) in the vulcanization bladder by a conventional pressure sensor used in the prior art attached to the upstream side of an on-off valve of a discharge passage, promptly detecting the occurrence of the product failure due to the occurrence of moisture bare in high precision, and thereby capable of remarkably decreasing the number of the scrapped product tires.SOLUTION: Pressurized steam is supplied via a supply passage 1 for a predetermined period into the vulcanization bladder 3 in which both the opening end portions of a tubular flexible film are airtightly sealed by a pair of respective ring members. Then a predetermined pressure is given into the vulcanization bladder 3 with the discharge passage 2 closed. the presence of a decrease in the hydraulic pressure in the bladder 3 is detected by the pressure sensor 5 attached to the upstream side of the on-off valve 4 of the discharge passage 2, and based on the detection of the decrease of the hydraulic pressure there is detected the occurrence of the abnormal vulcanization of the tire due to the generation of pinhole-like small holes (≤1) in the vulcanization bladder 3.