| 摘要 |
A piercing apparatus compact in size having a decreased number of hoses is suited for use as an iron runner port-opening machine for a blast furnace or the like furnace in an iron mill. The piercing apparatus executes the piercing by moving back and forth, by using a feed unit, a drifter equipped with a forward-blowing unit, a reverse-blowing unit and a rotary unit, and wherein cylinders containing a cylindrical blowing piston are provided in front of, and at the back of, a drifter body maintaining a distance relative to each other; a shank rod having, formed as a unitary structure, a blowing portion of a large diameter with blowing surfaces formed on the front and rear portions thereof and rod-like small-diameter portions protruding forward and backward beyond the blowing portion, is provided along the axial direction of the drifter body in a manner that the blowing portion is positioned between the front cylinder and rear cylinder and that the small-diameter portions on both sides are fitted to the cylindrical blowing pistons of the respective sides; and valves are provided in the outer peripheral portions of the front and rear cylinders to supply hydraulic pressure into the cylinders.
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