Patent ID: 7850439

Claim:
A vent plug for a tire vulcanization mold mounted in a vent hole of the tire vulcanization mold, the vent plug comprising: a plug holder having a hollow ventilation portion; and a plug head fitted within the ventilation portion, wherein the plug holder includes a tapered seat portion, an inside diameter of which becomes smaller toward a mold rear side, and a cylinder portion located at the mold rear side of the seat portion, the plug head includes a tapered head portion, an outer diameter of which becomes smaller toward the mold rear side, a base body portion located at the mold rear side of the head portion, and a slit portion communicated with the ventilation portion from an upper end face of the plug head, wherein the slit portion in the plug head is constructed and designed so that the slit portion provides elastic forces which resist the closing of the vent, until, when the vent plug is in use, a tire being vulcanized presses on and closes the vent, and the elastic forces reopen the vent after the tire is removed, and when defining an inside diameter at an upper end face of the plug holder as D 1 , and an outer diameter at an upper end face of the plug head when the slit portion is opened as D 2 , D 1 <D 2 is satisfied, and when defining a taper angle of the seat portion as a 1 , and a taper angle of the head portion as α 2 , α 1 <α 2 is satisfied.