Control for automatic machine tool drive

In a drive system wherein a variable speed electric motor produces cyclical movement of a slide along a path, a control system adapted for connection to the motor power supply comprising:

• encoder means producing a constant number of electrical pulses during each revolution of the motor shaft;
• means for determining a reference position of the slide and for initializing the control system;
• a memory wherein coded, predetermined paired values of slide velocity and position relative to the reference position are stored, the pairs defining the desired velocity and position of the slide at points along the slide path at which the rate of change of slide velocity with respect to slide position changes abruptly;
• means for computing target slide velocity-position paired values, each pair corresponding to a slide position intermediate the slide position of the predetermined pairs;
• data processing means comprising a binary counter for counting and registering encoder pulses following initialization, the count representing the actual position of the slide with respect to the reference position;
• a microprocessor adapted to produce a digital signal representing a computed slide velocity corresponding to a slide target position;
• and a comparator receiving input signals representing a slide target position and the actual slide position, producing an output signal when said input signals are identical, whereby the signal representing the computed slide velocity corresponding to the slide target position is produced by the microprocessor if the output signal is received from said comparator;
• and
• means for converting the output signals of said processing means to an analog voltage whose magnitude determines the velocity of the slide and whose polarity determines the sense of direction of the slide.