When vulcanizing a tire, unnecessary air becomes trapped in the tire vulcanization mold, and gas is produced by vulcanization. This air or gas produces vulcanization defects such as insufficient filling with rubber of the tire to be vulcanized. Therefore, tire vulcanization molds include an exhaust means for evacuating the air or gas produced when vulcanizing to the outside.
A structure in which a narrow hole that forms an exhaust groove is provided in the tire molding surface, and by embedding a blade so that it fits in this narrow hole, a small gap is formed between the blade and the long side of the narrow hole has been proposed as the exhaust means (see Japanese Unexamined Patent Application Publication No. 2009-269363). Air and/or gas are evacuated out of the mold through this small gap.
However, if the blade is weakly embedded in the exhaust groove, during vulcanization of the tire, the blade shifts and the size of the small gap can vary. In this case, stable evacuation of the gas cannot be ensured during vulcanization and tire vulcanization defects are likely produced. Also, there is concern that the blade could fall out of the exhaust groove as a result of continuous use of the mold.