PURPOSE: To discharge the core sand in an as cast product in a short time without the plastic deformation or breaking of the as cast product.
CONSTITUTION: An as cast product in which the core sand is filled and having sand discharging ports 3, 4 is struck by air hammers (a), (b), (c), (d) with the prescribed impact force and frequency. After the core sand 2 is broken, the blow whose force is larger than that of the blow to break the core sand 2 and whose frequency is higher than that of the blow to break the core sand 2 is given by the air hammers (a), (b), (c), (d). The force toward the sand discharging ports 3, 4 where the density of the core sand is lower is received by the broken core sand 2 with the small impact force, and much of the force toward these sand discharging ports is received with the higher frequency, and the core sand can be discharged in a short time without deforming or breaking the as cast product.
OGATA ISAO
NAGAI SHUSUKE
MAKINO SHUZO
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