Abstract: A failure detecting apparatus for a dual valve provided in a pneumatic circuit for a slide of a press machine, which comprises an air tank containing compressed air therein, a clutch and brake mechanism for the slide selectively connectible with the air tank, a pair of solenoid valves connected in parallel with the air tank and the clutch and brake mechanism, each of the solenoid valves having two positions wherein the clutch and brake mechanism is connected to atmosphere when the solenoid valve is at first position and is connected to the air tank when the solenoid valve is at second position, and a pressure operated switch interposed between the solenoid valves and the clutch and brake mechanism wherein the pressure operated switch is adapted to be turned on and off for each cycle of the slide when both solenoid valves are in good working order.

Abstract: Process and apparatus are disclosed for automatically interchanging die assemblies in a metal working press having a pair of moving bolsters to be used alternately in the press. An initial condition setting device having control circuits connected to various portions of the press for setting data such as the number of products, the pressing force of the slide of the press for working, the die height for different die assemblies, the balancer air pressure, the die cushion stroke, the die cushion air pressure, the kind of operation of the die cushion for the drawing, the locking or the shearing and the blank holder air pressure is provided for sequentially carrying out various steps.