Abstract: Prior art adaptive control systems for numerically-controlled milling machines are first discussed in which N/C instructions and adaptive control system data are obtained and stored in a storage medium utilizing a software routine which takes into consideration parameters of the milling process and parameters of a specific milling machine. The instructions and data command, for sequential steps in the milling process, such items as spindle position, feedrate and reference milling forces and are supplied to an N/C unit and to the adaptive control system at the milling machine to automatically control the milling process. The adaptive control system includes a milling force sensor and functions to override the commanded feedrate on comparison of the actual milling forces during the process with the reference milling forces.

Abstract: A circuit for controlling the application of an error compensation circuit in a feedback control system which in turn automatically controls the feedrate of a machine tool apparatus such as a milling machine. Sensors positioned adjacent the spindle of the apparatus measure the amount of force on the spindle under load conditions, and provide an electrical signal output. The electrical signal includes an error component, substantially caused by the revolving mechanial components of the apparatus, such as the spindle, being out of true. If the electrical signal provided by the sensors does not exceed a pre-established threshold voltage, a low-pass compensation filter is applied in the feedback control system, removing the error component but introducing a time constant into the electrical signal and hence a delay in feedback control.