MOLDING METHOD OF GREEN SAND CORE

摘要

PURPOSE:To mold a green sand core having substantial strength and good venting and collapsing properties by packing green sand into the cavity of a core box into which a bar member is preliminarily inserted to form a hollow green sand part and exploding a gas in the hollow green sand part. CONSTITUTION:Green sand is charged into the hollow part 7 of a cylindrical body provided to a sand blowing device 6 and the open top end of a vessel body 5 is hermetically closed then the bottom surface of the device 6 is pressed to the top surface of the box 1 to clamp the box. When compressed air is introduced into the device 6 by opening a valve 12, the green sand in the part 7 is packed through a sand blow hole 19 into the cavity 3 of the core box 1. The device 6 and the box 1 are then separated. A combustible gaseous mixture composed of a specific ratio of fuel and oxygen is supplied to the hollow green sand part and a switch is turned on to generate spark then the gaseous mixture in the hollow green sand part explodes and the green sand in the cavity 3 is strongly compressed, by which the desired core is obtd.