RESIN-COATED SAND FOR MOLDING LAMINATED LAYER AND METHOD FOR MOLDING LAMINATED LAYER USING RESIN-COATED SAND

摘要

PROBLEM TO BE SOLVED: To obtain the high precision and high quality in the shape and the dimension of a molded material by forming sand grain coated with resin to a specific spherical shape. SOLUTION: By using laminated layer molding method, the resin-coated sand 50c prepared by coating the resin on the almost spherical sand grain having 20-100 m grain diameter are produced, and a spreading process for forming thin sand layer by spreading the resin-coated sand 50c and an irradiating process for hardening the resin by irradiating the sand layer 50 with laser beam are executed. The spreading process and the irradiating process are alternately repeated to laminate the sand layer in the thickness direction and then the molding is executed. It is favorable that the thermal expansibility of the sand grain is low. In this way, at the time of irradiating and heating the sand grain with the laser beam, the thermal expansion of the sand grain can be restrained and the precision of the molding material can be secured, and the strain and the core cracking caused by thermal deformation at the time of casting, can be suppressed. In the consideration of secureness of the precision of the molding material, it is desirable that the m.p. of the resin is =100 deg.C.