Abstract: Downfeed apparatus in a grinder controlling the grinding wheel down in fast, medium and slow speeds, and up in fast speed. It is fed down continuously in successive passes throughout the grinding operation, and at the end of the grinding, the grinding wheel continues through a spark-out mode at a constant level. A previous control program is held in a memory for later use in an identical operation on an identical workpiece. A monitor presents all steps taken in every mode and every step, and shows progress of movements enabling the operator to manually set and adjust the control apparatus simply and accurately by watching the monitor while making the adjustments. The monitor also continuously presents all movements in an automatic operation.

Abstract: In a grinder, the table carrying the workpiece to be ground reciprocates to carry it past a grinding wheel. The table moves armatures oppositely into and out of respective coils, inducting voltage therein for driving the reversible motor that moves the table. Remote coils with manually settable armatures therein oppose the first coils for determining the range of movement of the table. A control circuit includes right and left halves corresponding to the directions of movement of the table. Right and left SCR's control the current from first coils to the drive motor, transistors control the gating current to the SCR's; triacs control the current from the transistors, and other triacs control the current from the main source to the drive motor.