METHOD AND APPARATUS FOR FORMING VENT HOLE FOR TIRE MOLD

摘要

PURPOSE:To simplify stages and to exactly position vent holes by casting a tier mold with a gypsum master pattern inserted with projections as a master pattern and machining the molded bevel parts thereby forming the vent holes. CONSTITUTION:The projecting parts 3 and groove parts 4 of the same pattern as the pattern on the surface of a tire are formed on the surface 2 of the gypsum master pattern 1. The many projections 5 are provided on the gypsum surface 2. The shapes of the head parts of the projections 5 form the bevel shapes when cast. A tip 12 of a drill 11 is placed to the part of the bevel 10 and the bevel part is drilled to form the vent hole 9. A series of stages are thereby simplified and the finishing operation is made simple.