| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for rebonding molding sand by controlling the rebonding degree of the sand at the simpler method than the conventional method, and a method for making a mold for casting using synthetic mullite sand rebonded in the above rebonding method, when the molding sand recovered from the mold obtained by using the synthetic mullite sand as the molding sand, a water-soluble phenolic resin as a binder and an organic ester compound as a hardening agent is thermally rebonded. SOLUTION: This molding sand uses the synthetic mullite sand and the water-soluble phenolic resin is used as the binder. When the molding sand recovered from the mold obtained by hardening with the organic ester compound is rebonded with a heating-treatment, as a value for controlling the rebonding degree of the sand, a pH measured value with a JACT molding sand testing method, S-3 "the pH testing method of the molding sand" is used and this value is controlled to 9.7-10.6 so as to perform the rebonding treatment at the first step of the heating-treatment. COPYRIGHT: (C)2004,JPO&NCIPI
|
