Pneumatic feeder for punch presses

Claim 1

In a pneumatic feeder for intermittently advancing stock into the work station of a punch press or the like, and having a frame; feed slide means mounted on said frame for reciprocating movement in index and stock feed directions; actuating means for actuating said feed slide means in said index and feed directions; stock gripping means carried by said feed slide means and adapted to be moved between stock releasing and stock gripping conditions; fluid motor means for actuating said stock gripping means; and control means for controlling the operation of said actuating means and fluid motor means whereby said stock may be intermittently gripped and advanced in said feed direction, said control means including a primary air valve having an output line for normally controlling the operation of said fluid motor means; the improvement comprising a piloted supplementary air valve having a first operative condition for normally permitting said primary air valve to control said fluid motor means, and a second operative condition for overrriding the said normal control of said fluid motor means by said primary air valve and for controlling said fluid motor means so as to cause said stock gripping means to be moved to a stock releasing condition independent of, and without controlling, the operation of said actuating means for said feed slide means; air jet means adapted to issue a jet of air for sensing the arrival of said feed slide means at the terminal portion of a feed stroke of said feed slide means, and for generating an output signal when said arrival in sensed, said air jet means comprising a nozzle and means defining a signal output line, said air jet means being adapted to generate an air output signal for controlling said supplementary air valve; and fluid operated means responsive to an output signal from said air jet means for shifting said supplementary air valve from its said first operative condition to its said second operative condition when said air jet means senses the completion of a stock feed stroke of said feed slide means for causing said fluid motor means to operate so as to permit said stock gripping means to move to a stock releasing condition shortly after completion of said stock feed stroke and without causing the initiation of an index stroke of said feed slide means.