Die cushion controlling apparatus and die cushion controlling method

A die cushion controlling method for controlling an operation of a cushion pad, comprising:

• a position control step of measuring a position of the cushion pad and controlling the position of the cushion pad so that a position measured value follows a preset position pattern;
• and
• a load control step of measuring a load generated in the cushion pad and controlling the load generated in the cushion pad so that a load measured value follows a preset load pattern, wherein:
• the position control step is switched to the load control step at a time when the load starts to be generated in the cushion pad, and
• the load control step is switched to the position control step at a time when the load generated in the cushion pad vanishes.

A die cushion controlling apparatus for controlling an operation of a cushion pad, comprising:

• a pad drive mechanism raising and lowering the cushion pad while applying an upward energizing force;
• a load measuring device measuring a pressure generated in the cushion pad;
• a sensor measuring at least one of a lowering and raising direction and a speed of the cushion pad;
• and
• a pad controller comprising a pressure pattern, a position pattern, a pressure comparator, a pressure controller, a switching unit, a speed comparator, a speed controller, a current comparator, a current controller, a current detector, a position comparator, and a position controller,
• the pressure comparator receiving a pressure control signal representative of the pressure pattern and pressure feed back signal from the load measuring device, and outputting a pressure correction signal;
• the pressure controller receiving the pressure correction signal and outputting a first motor speed control signal;
• the position comparator receiving a position control signal representative of the control pattern and a position feedback signal from the sensor, and outputting a position correction signal;
• the position controller receiving the position correction signal and outputting a second motor speed control signal;
• the switching unit receiving and switching between the first motor speed control signal and the second motor speed control signal;
• the speed comparator receiving output from the switching unit and receiving a speed feedback signal from the sensor, and outputting a motor speed correction signal;
• the speed controller receiving the motor speed correction signal and the speed feedback signal and outputting a current control signal;
• the current comparator receiving the current control signal and a current feedback signal from the current detector, and outputting a current correction signal;
• the current controller receiving the current correction signal and outputting a supply current signal;
• and
• the current detector receiving the supply current signal, and outputting the current supply signal to the pad drive mechanism and the current feedback signal to the current comparator.