SELBSTTAETIGE RUECKFUEHRUNG UND RUECKKEHR EINES WERKZEUGES EINER NUMERISCH GESTEUERTEN WERKZEUGMASCHINE

摘要

A general safe retract and return function is provided for a machine tool which is easily programmed for all cases to avoid collision and interference between the workpiece and tool and to reduce the damage or imperfection in the surface of the machined workpiece caused by the termination and/or resumption of machining. The general safe retract and return function includes parameters defining incremental retract and entry vectors relative to the direction of the machining path in the region of the interrupted point. Preferably the tool and workpiece are reengaged at the interrupted point along an entry ventor which is at a grazing angle with respect to the reverse of the tool feed direction along the machining path, thereby avoiding remachining of the workpieces but providing a smooth surface finish. Preferably the general safe retract and return function interprets programmer specified conditional expressions to determine when logical jumps should be performed to disengage the tool and workpiece and execute respective user-defined interrupt subroutines for corrective action. Preferably the logical jump for certain limit conditions or trigger signals is conditional based upon the engagement and disengagement of the tool and workpiece as specified by rapid traverse and feed rate moves, beginning and ending distances for the feed rate moves, and the depth of cut at the beginning and ending points of the feed rate moves.