Machine tool control with adjustable limit control

Claim 1

A MACHINE TOOL CONTROL APPARATUS FOR USE WITH A MULTIPASS MACHINE TOOL WHOSE MODE OF OPERATION INVOLVES SUCCESSIVE CYCLES OF MOVEMENT INCLUDING IN EACH CYCLE A MOTION IN A FIRST DIRECTION AS A WORKING TOOL ENGAGES AND WORKS A WORKPIECE, A WITHDRAWAL TRANSVERSE MOTION AS THE WORKING TOOL IS WITHDRAWN FROM THE WORKPIECE AT THE END OF A REQUIRED MOTION IN THE FIRST DIRECTION, A MOTION OPPOSITE TO THE FIRST DIRECTION TO RETURN THE WORKING TOOL FOR ANOTHER WORKING OPERATION, AND A TRANSVERSE MOTION AS THE WORKING TOOL IS MOVED INTO THE WORKPIECE, THE APPARATUS COMPRISING; A TEMPLATE ADAPTED TO BE MOUNTED IN RELATION TO THE WORKPIECE, THE CONTOUR OF SAID TEMPLATE DETERMINING THE FINAL CONTOUR OF THE WORKPIECE AS PRODUCED BY THE WORKING TOOL, A SIGNAL PRODUCING STYLUS ADAPTED TO BE MOUNTED FOR MOVEMENT WITH THE WORKING TOOL AND ADAPTED TO PRODUCE CONTROL SIGNAL MEANS WHEN IN ENGAGEMENT WITH SAID TEMPLATE, PLURAL STEP SIGNAL PRODUCING MEANS TO CONTROL THE MAXIMUM WORK TO BE PERFORMED BY WORKING THE TOOL FOR SUCCEEDING MOVEMENTS OF THE WORKING TOOL IN THE FIRST DIRECTION, FIRST SIGNAL PRODUCING MEANS INDICATIVE OF THE POSITION OF THE WORKING TOOL AS IT MOVES IN TRANSVERSE MOTION INTO THE WORKPIECE, SECOND SIGNAL PRODUCING MEANS INDICATIVE OF THE POSITION OF THE WORKING TOOL AS IT MOVES IN THE DIRECTION OPPOSITE TO THE FIRST DIRECTION, THIRD SIGNAL PRODUCING MEANS INCLUDING A CONTROL MOTOR, FIRST MEANS CONTROLLED BY SAID SIGNAL PRODUCING STYLUS AND BY SAID PLURAL STEP SIGNAL PRODUCING MEANS AND CONNECTED TO CONTROL THE TRANSVERSE MOTION OF THE WORKING TOOL INTO THE WORKPIECE AND THE WORKING TOOL MOTION IN THE FIRST DIRECTION TO CAUSE THE WORKING TOOL TO FOLLOW THE TEMPLATE CONTOUR UNTIL THE MAXIMUM WORK IS PERFORMED AS CONTROLLED BY SAID PLURAL STEP SIGNAL PRODUCING MEANS, SECOND MEANS INCLUDING MEANS CONTROLLED BY SAID PLUTAL STEP SIGNAL PRODUCING MEANS AND BY SAID FIRST SIGNAL PRODUCING MEANS TO CONTROL SAID CONTROL MOTOR TO ENERGIZE THE SAME UNTIL SUCH TIME AS THE MAXIMUM WORK IS PERFORMED BY THE WORKING TOOL AND TO THEN INTERRUPT THE CONTROL THEREOF, WHEREUPON SAID THIRD SIGNAL PRODUCING MEANS PRODUCES A MEMORY SIGNAL WHICH IS A MEMORY OF THE POSITION OF THE WORKING TOOL IN THE FIRST DIRECTION OF MOTION WHERE THE WORKING TOOL NO LONGER FOLLOWED THE TEMPLATE, THIRD MEANS EFFECTIVE AT THE AT END OF THE REQUIRED MOVEMENT IN THE FIRST DIRECTION TO INSTITUTE THE WITHDRAWAL TRANSVERSE MOTION OF THE WORKING TOOL AND THEREAFTER TO INSTITUTE THE MOTION OPPOSITE TO THE FIRST DIRECTION, AND FOURTH MEANS CONTROLLED BY SAID SECOND SIGNAL PRODUCING MEANS AND BY SAID THIRD SIGNAL PRODUCING MEANS TO COMPARE THE SIGNAL OF SAID SECOND SIGNAL PRODUCING MEANS TO SAID MEMORY SIGNAL AND TO INTERRUPT THE MOTION OPPOSITE TO THE FIRST DIRECTION UPON THE WORKING TOOL REACHING THE POSITION WHERE THE WORKING TOOL NO LONGER FOLLOWED THE TEMPLATE.