| 摘要 |
PURPOSE:To obtain a tire wherein generation of a bare is prevented and a cut-off mark of a spew not conspicuous, by a method wherein an annular groove whose cross section is of a triangular form is provided in the inside of a mold along a position of the tire where a width of the cross section is maximum and an exhaust hole communicating from the bottom of the annular groove with the outside of the mold is provided. CONSTITUTION:An annular groove 15 whose cross section is of a triangular form is provided along a position 12 where a width of the cross section is maximum. With this construction, at the time of vulcanization and molding of a green tire, rubber flows toward the annular groove 15 from both sides of the annular groove 15 and the annular groove 15 is filled with the rubber. Air moved according to a movement of the rubber is accumulated on the groove bottom 18 of the annular groove 15 and discharged outside of a mold through a vent hole 19 from the groove bottom 18. Unvulcanized rubber is hard to flow to a narrow part as the viscosity of the same is high. Therefore, the groove bottom 18 of the annular groove 15 is filled with rubber, only when the rubber is heated and the viscosity is lowered. Therefore, the air can be discharged completely due to the fact that there is a time difference until the groove bottom 18 is filled with the rubber from the closure of the mold, and a few vent holes 19 are provided at appropriate intervals. |
