Protected rocker-arm safety device for presses

摘要

A rocker-arm safety device which rotates into and out of the path of the movable platen on a press. When in the latter position, it allows the press to proceed normally through its usual operating cycle. When in the path of the platen, it protects an operator's hands in the working area by preventing the press from closing. A power source, separate from that for the press, rotates the arm between its positions. This assures its proper safety functioning notwithstanding some malfunction in the primary power source. To avoid damaging the axle on which the rocker arm pivots, the device includes a bar which contacts the arm when lying in the platen's path. The arm then transmits the force received from the platen to the bar, rather than to the axle. With no need to bear the weight of the press, the axle may move on needle or ball bearings to minimize the force needed to change the rocker arm's position. Where an air cylinder moves the rocker arm between positions, it may have ball- or needle- bearing couplings to the rocker arm and to the device's structure. Locating its coupling to the rocker arm at least three-fourths of the distance between the axle and its contact with the press facilitates the movement of the rocker arm and minimizes destruction of the cylinder.