JPS55147455A - Molding method of self-hardening mold - Google Patents

Abstract

PURPOSE: To obtain the smooth mold surface which permits as cast and enable hardening in a short time by keeping the mold surface forming wall parts of the frame constituting a molding spacing and the wall surfaces opposing to these at ordinary temperature and high temperture respectively and packing self-hardening molding sand into the molding spacing.

CONSTITUTION: An annular core box 7 is inserted onto the barrel-form part 4a of a perpenducular core ring 4 and is placed on a flat plate part 4b. The core box 7 is split to two in the same direction and has flanges 8a, 8b at its top and bottom edges of the outside surfaces. A frame 9 is constituted by the core ring 4 and core box 7 and the molding spacing is formed by the annular spacing between the both. The barrel-form part 7a of the core box 7 assumes the mold surface forming wall part of the frame 9. Before the core ring 4 is combined with the core box 7, it is heated to a high temperature of about 130W180°C. The core box 7 is kept at an ordinary temperature. Self-hardening molding sand 10 such as the one comprising mixing phenolic resin and hardening accelerator to sand is packed in the molding spacing while being compacted. The sand 10 heats up subsequently from the portion in contact with the core ring 4 to the core side by the heat of the core ring, thereby hardening.

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