| 摘要 |
PURPOSE:To obtain a mold which does not require cold insulation during the time from setting and hardening until charging of molten metal by utilizing a binder of specific melting point as a binder for frozen molds. CONSTITUTION:Molding sand added with a binder of 5-60 deg.C m.p. is heated to above said melting point and is packed in a pattern box, after which the molding sand is forcibly cooled down to below said melting point, whereby it is set and hardened. The binder used here is required to be higher in melting point than the atmospheric temp. in a working shop and since large quanity of heat is not needed for heating and cooling, it is required to be not too high in melting point and to be higher by about 20 deg.C than said temp. Further, it is required to have strong binding force in a set state, to form a firm mold at ordinary temp., to have good mold collapsibility after charging and to permit repeated use of molding sand. To this end, ethylene glycol, wax consisting essentially of paraffin, etc. are used as the binder. |
