| 摘要 |
PURPOSE:To improve the formability and strength of a core for forming vent hole by using a ceramic mold material as the core for forming the vent hole extending in parallel direction to surface of a tire for skeleton part of a tire mold. CONSTITUTION:The annular core 1 made of gypsum for forming the tire has the shape dividing the product tire into two pieces from the center face. The core 3 for forming the vent hole is fitted so as to bridge between side walls of grooves 2 corresponding to tread pattern. A ceramic mold material mixing binder of ethyl silicate with zircon flower is formed and hardened to shape, which the center part is constricted in inner part of a rubber mold, and after separating from the mold, the core 3 burnt at red heat with a propane burner is used. The core 3 is embedded with packing material 4 of the gypsum, etc. The gypsum-made core 1 is set on a surface plate 5 and the molding flask 6 is covered and molten Al alloy is poured into cavity part between the outer circumferential face of the core 1 and the molding flask 6. The tire mold 7 is taken out, and by executing honing, the core 3 is easily removed and the tire mold 7, in which the vent hole 8 is formed in the skeleton part 9, can be obtd. |
