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Patent Searching and Data

Document Type and Number:
Japanese Patent JPH0220337
Kind Code:
A booster for the cusion-knockout mechanism (62) associated with the slide (61) of a press-machine (60) serves to stably hold down a work plate such as a printed board and the likes while performing a cushioning operation during a pressing or punching stroke and serves to knock the work plate out from the punches (68) after the pressing stroke has been completed. The booster is connected to a hydraulic actuation chamber (64) of a cushion cylinder (63) provided in the slide of the press-machine by valve means (27) comprising a valve body portion (44) within a valve casing (22) and a knockout actuator (28) which is fixedly secured to the valve casing so as to perform the valve opening operation of the valve means. The valve means are adapted to push a valve body toward the valve closing side by the resultant force obtained from a spring force of a valve closing spring (31) and the pressure in the valve chamber and to push the valve body toward the valve opening side by a pressure in a back pressure cylinder (40), which is connected to the valve chamber so that the force which pushes the valve body toward the valve closing side is decreased by the body toward the valve closing side is decreased by the back pressure applied to the valve body.

Application Number:
Publication Date:
May 09, 1990
Filing Date:
December 26, 1986
Export Citation:
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International Classes:
B21D24/02; B21D45/00; B21D45/04; B26D7/18; F15B3/00; H05K3/00