MOLDING METHOD OF BACK SURFACE PART OF VACUUM MOLDING MOLD AND PLACING DEVICE OF FILM ALONG BACK SURFACE PART OF VACUUM MOLDING MOLD

摘要

PURPOSE:To prevent the mold collapse of the back surface part accompanied with vacuum suction by heating the film of the portion corresponding to the sprue at the time of affixing the film under vacuum to the back surface of the mold which has been vacuum-molded. CONSTITUTION:An elevating cylinder 3 is moved upward to place the pattern 12 on a turntable 10 on a vibration plate 8, after which the flasks 17 in a connected state carried by conveying rollers 16 are pressure-contacted to the shield plate 22 of a hopper 20. The shield plate is opened by operating a cylinder 25 to pack sand grains in the flasks, after which a mold 47 is formed by a vacuum molding method. Thence, the flasks are detached from the shield plate and are engaged with the main frame 34 carried in by conveying rollers 33, thence the film 42 stretched to a holding frame 40 is vacuum-affixed to the back surface part 49 of the mold. At this time, the film of the portion opposing to a sprue 48 is softened by a heater 43, by which the mold collapse accompanied with vacuum suction may be prevented.