High-pressure bulge-forming system for tubular workpieces

A method of operating an apparatus for high-pressure bulge forming of tubular workpieces, the apparatus comprising:

• an upper die plate facing generally downward and extending at an acute angle to a vertical plane;
• a lower die plate generally parallel to and confronting the upper die plate, one of the plates being movable along an axis generally perpendicular to the plates toward and away from the other die plate;
• respective upper and lower die halves carried on the die plates and matable together to form a die cavity having open ends and adapted to receive a one of the workpieces with ends of the workpiece exposed at the open ends of the die cavity, the upper die half opening downward;
• means for displacing the one die plate and the respective die half toward and away from the other die plate;
• respective actuators on the upper die plate having heads engageable with the ends of the workpiece in the die cavity;
• pressurizing means including a passage extending through one of the actuator heads for internally pressurizing the workpiece in the die cavity for bulge-deforming the workpiece;
• a supply of the tubular workpieces;
• means including a robot for fitting a workpiece from the supply and fitting it to the upper die half;
• and
• means below the upper die half for catching workpieces dropped therefrom;
• the method comprising the steps of:
• a) displacing the die plates and halves apart into an open position,
• b) fitting a workpiece from the supply to one of the die halves with the robot,
• c) displacing the die plates and halves together into a closed position,
• f) internally pressurizing the workpiece to bulge form it to the die cavity,
• e) depressurizing the workpiece and displacing the die plates and halves apart,
• f) retracting the heads from engagement with the workpiece and dropping the workpiece from the upper die half, and
• g) repeating steps b) through f) with another workpiece.