Thomas R Frecka

US Patent:

42374081, Dec 2, 1980

Filed:

Aug 10, 1979

Appl. No.:

6/065583

Inventors:

Thomas R. Frecka - Cincinnati OH

Assignee:

Cincinnati Milacron Inc. - Cincinnati OH

International Classification:

G05B 1924

US Classification:

318571

Abstract:

A method and apparatus are disclosed for controlling a machine tool as a function of the torque load on a cutting tool. The apparatus detects the spindle motor current which may vary over four decades, the spindle motor voltage which may vary over two decades and the cutting tool angular velocity which may vary over three decades. The decimal values of the detected variables are converted to corresponding logarithmic values and stored in digital form. A microprocessor utilizes the stored values to calculate the value of torque on the cutting tool which may vary over five decades. A microprocessor determines the idle torque by averaging the torque which is measured several times over one spindle revolution. The idle torque is subtracted from subsequent gross torque measurements to provide an indication of actual cutting load on the tool. The operation of the machine is modified in response to the actual torque exceeding a predetermined reference torque value.