| 摘要 |
PROBLEM TO BE SOLVED: To provide a heading machine capable of reliably preventing any breakage of a die or a punch and any locking phenomenon at the front dead center of the punch even when any overload pressure is applied. SOLUTION: The heading machine comprises: a punch 5 held by a ram 4; a tapered pressure bearing plate 10 which is provided on a rear part of the punch 5 to change the protrusion of the punch 5 from a ram front side by the upper and lower movement; a threaded shaft 12 provided on an upper part of the pressure bearing plate 10; a supporting member 11 which is provided on the ram 4 to support the threaded shaft 12 in a vertically movable manner; and a hydraulic cylinder 16 which is interposed between the supporting member 11 and the threaded shaft 12, raises the threaded shaft 12 together with a piston 15 by applying hydraulic pressure from a lower part to the piston 15 provided on the threaded shaft 12 during the normal operation, and positionally holds the pressure bearing plate 10 at the upper set position. A valve mechanism 17 to release the overload pressure to a tank T when a hydraulic pressure greater than the set value is applied to the hydraulic cylinder 16 is provided, and a forcible retracting mechanism 18 to forcibly lower the threaded shaft 12 in an interlocking manner with the releasing operation of the overload pressure, and rapidly move the pressure bearing plate 10 to the lower retraction position permitting the retraction of the punch 5 is provided. COPYRIGHT: (C)2003,JPO
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