Clutch-brake drive control for press machine

An apparatus for drive control of a clutch-brake of a press machine by turning a double solenoid valve on and off, comprising:

• a pair of solenoid driving circuits, in each of which there are provided a solenoid of said double solenoid valve, an AC power supply and a semiconductor element for switching said AC power supply;
• running command pulse signal generating means for generating a running command pulse signal synchronized with the AC power supply, said running command pulse signal indicative of an ON-OFF condition of a running button;
• zero-cross synchronized pulse signal generating means for generating a zero-cross synchronized pulse signal synchronized with a zero-cross point of the AC power supply;
• two lines of drive control signal generating means for generating respective drive control signals, and outputting the drive control signals to the semiconductor elements under the condition that the running command pulse signal is recognized as valid through synchronization of said running command pulse signal and said zero-cross synchronized pulse signal;
• collating means for collating operations of the two lines of drive control signal generating means, judging whether the collated operations are in coordination, and forcibly cutting off the AC power supplies of said solenoid driving circuits when said operations of said drive control signal generating means are judged as not in coordination;
• and
• two lines of fault detecting means, comprising a pair of synchronized signal generating means connected in parallel to said semiconductor elements of said solenoid driving circuits, and for detecting a fault of said semiconductor elements by detecting a combination of output conditions of synchronized signals, issued from said synchronized signal generating means when said semiconductor elements are in an ON condition, and said drive signal, and for forcibly cutting off said AC power supplies of said solenoid driving circuits when the fault is detected.

A drive system for a press, comprising:

• a valve;
• a solenoid for opening and closing said valve;
• a solenoid driving circuit, including:
• an AC power supply, and
• a semiconductor device, responsive respectively to the application and removal of a drive control signal to be turned ON and OFF, for connecting and disconnecting the AC power supply with respect to said solenoid, said power supply and said semiconductor device connected in series to said solenoid;
• running command pulse signal generation means for generating a running command pulse signal synchronized with the power supply, said running command pulse signal generation means including a running button having an ON state and an OFF state, the running command pulse signal indicative of the ON or OFF state of said running button;
• zero-cross synchronized pulse signal generating means for generating a zero-cross synchronized pulse signal synchronized with a zero-cross point of said power supply;
• drive control signal generating means for:
• comparing the running command pulse signal and the zero-cross synchronized pulse signal, and
• generating the drive control signal and applying the drive control signal to said semiconductor element, only when the running command pulse signal and the zero-cross synchronized pulse signal are in synchronization;
• synchronizing signal generating means for generating synchronized signals synchronized with the power supply if said semiconductor element is OFF;
• means, responsive to a combination of the synchronized signals and the drive control signal, for detecting a fault of said semiconductor element;
• and
• means for forcibly cutting off the power supply from said solenoid when the fault is detected by said detecting means.