This application relates to electronic circuitry to control the feeding of sheet stock in the form of thin metal strips from a roll or reel to a stamping machine, such as a punch or transfer press. In each stamping cycle of the machine, during the time when the reciprocating member is clear of the stock, the feed actuators advance the stock through appropriate incremental steps suitable for moving the stock longitudinally and for shifting it laterally normal to the direction of advance. This results in multiple staggered rows of stampings, and of course provides a considerably more efficient use of the strip material resulting in reduction of waste.
In the past, this type of stagger feed control has been done mechanically, but mechanical control is quite expensive and requires substantial maintenance. Pneumatic logic circuitry has also been used, but suffers from slowness of operation, variations in air pressure, and air purity problems caused by dirt, oil, water. Moreover, pneumatic logic circuitry is relatively complex, and the complexity increases greatly when the number of staggered rows is increased.
The use of electronic circuitry is far superior for the reasons that will be discussed hereinafter under the objects and advantages of the present invention, and of course it is in common use in machine control systems as shown in various patents such as Schneider et al, U.S. Pat. No. 4,062,213.