| 摘要 |
PURPOSE:To produce a core mold of good surface stability that withstands handling operations and to prevent the production of excess green sand at the same time, by freezing and hardening the molding sand for green sand molds packed in cavities. CONSTITUTION:A metallic mold pattern box 2 is sandwiched between a table 1 and a blowing head 8 as a table 1 ascends. It is cooled by the liquid nitrogen supplied through a liquid nitrogen introduction pipe 5 and ejecting through many nozzles 7. When the box 2 is cooled down to a prescribed temp., molding sand 9 for green sand molds contg. a proper amt. of moisture and a binder is blown into the cavities of the box 2 from the head 8, whereby it is packed therein. Upon cooling of the molding sand 9 for a prescribed time, the box 2 is opened, and the core mold which is frozen and solidified at the surface is removed. If necessary, the surface thereof is coated with graphite or the like together with a binder so that it is stabilized. |
