To provide a lower plate for preventing crack generation and the expansion of the crack connecting a molten metal discharge hole and a molten metal casting hole.
In the lower plate of the three-plate slide gate, a plate 4 is held in a rectangular holding frame 1, in which a middle plate is moved in the longitudinal direction by contacting tapers 5, 6 which are arranged on both surfaces in the moving direction at both edges, with the incline surfaces 9, 10 of half-wedge shaped press metal fittings 7, 8 arranged at four corners of the holding frame, and has a molten metal casting hole 2 and a molten metal discharge hole 3 separated to the moving direction. The taper of the molten metal discharge hole on both surfaces of the plate 4 is overlaid with the area A1 surrounded with lines L1, L2 which cross at right angles with the moving direction and touched to the inner wall of the molten metal discharge hole, or at least part of the incline surface of the press metal fitting at the side of the molten metal discharge hole is touched to the taper of the plate in the area.
KAWASHIMA TERUHISA
IZU DAISUKE
SUMITOMO METAL IND
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