Patent ID: 6344724
Filing Date: 2002-02-05
Classification: G05B

Abstract:
A numerical control apparatus for an NC machine tool comprising:a command generating and distributing section to generate an operation command signal according to a machining program; a feed drive controlling section to control an operation of a feed drive system on the basis of the obtained operation command signal; a spindle drive controlling section to control a rotational operation of a spindle drive system according to the machining program; cutting load detecting means to detect a cutting load on the basis of an electric current for driving that is output to the feed drive system from the feed drive controlling section and/or an electric current for driving that is output to the spindle drive system from the spindle drive controlling section, comprising a bite load detecting section to detect the cutting load at an early stage being in a stationary condition after a tool has contacted with a work piece, and a stationary load detecting section to detect the cutting load after the early stage; and pecking judgement means to judge that the feed drive system should be retracted on the basis of the cutting load detected by the bite load detecting section and the cutting load detected by the stationary load detecting section during a drilling process, pecking operation controlling means to make the feed drive system retracted on the basis of judgement of the pecking judgement means.