Positioning aid for machine tools - uses incremental encoder and counter with final position accuracy compared with predetermined tolerance

摘要

A positioning device for the table of a machine tool e.g. milling machine, is effected by an incremented encoder operating into a binary counter. A fast traverse followed by slo final approach is coupled with a comparison of final position with a permitted tolerance. The required position is selected together with the point at which fast traverse is disengaged and the number of steps to be made at slow final approach. A control stage generates the number of steps to be made with fast traverse. A comparator receiving the counter output generates the first change down signal and a second comparator the second change down dependent upon the number of increments required. A final stage compares the final positioned accuracy achieved with the accepted tolerance to indicate acceptance or reflection.