To smoothly remove core sand without using chemical method even in the case of being small diameter of an opening hole in a hollow part or complicate shaped recessed part in the inner peripheral surface in the hollow part by using a nozzle which can insert into the hollow part of a work and removes the sand core while injecting gas with a specific pressure from the tip part.
Firstly, the first nozzle 11 is faced to the one side of opening hole 3 in the hollow part 2 and shifted to the other side of opening hole 4 while injecting the high pressure air A having ≥0.8 MPa from the injection hole 11a. In this result, the core sand S1 at the center of the hollow part 2 is detached. At the time of communicating both opening holes 3, 4, the second nozzle 12 is inserted into the hollow part 2 from the one side of opening hole 3 while inserting the high pressure air A from injection holes 12a, 12b and slowly rotating. By this method, the core sand S2 in the recessed parts 5 of annular grooves 6, 7, bypass holes 8, etc., is removed by detachment with the turbulance of the air A and the linked detachment of core sands mutually.
IKEYAMA MAKOTO
HIRAGA MIKITOSHI
TANAHASHI SHIGERU
WATANABE MASATOMO
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