Press with control circuit arrangement

A press comprising a direct current drive electric motor having an output shaft;

• a slide ram;
• means for guiding the slide ram in reciprocating motion along a rectilinear path;
• reduction gearing and an eccentric drive shaft connecting the motor output shaft to the slide ram for driving the slide ram through cycles of reciprocating motion along said rectilinear path;
• and a control circuit arrangement comprising an encoder connected to the output shaft of the drive electric motor for producing a first output representing the angular position of the eccentric drive shaft and thus the linear position of the slide ram along said rectilinear path and means for controlling the speed of the drive motor to stop the slide ram at least proximate to a home position thereof at the end of each cycle of the slide ram;
• wherein the means for controlling the speed of the drive motor comprises a computer having registered therein a desired motor speed program, a motor control circuit electrically connected to the incremental encoder and to the computer, a motor drive circuit electrically connected to the motor control circuit and to the drive electric motor, and measuring means associated with the drive electric motor and being electrically connected to the motor control circuit, which measuring means produces a continuous second output representing the speed of the drive electric motor, the motor control circuit receiving and comparing said first and second outputs with said desired motor speed program to provide a third output representing the result of such comparison, said motor drive circuit being responsive to said third output to control the speed of said motor in accordance with the desired motor speed program.