Method for automatically varying the feed rate of a workpiece carriage in a machine tool

Abstract

A method for automatically varying the feed rate of a moving workpiece carriage in the proximity of permissible terminal positions for the carriage in a machine tool. The machine tool includes a numerical control means for controlling the position of the workpiece carriage and means for determining the position of the workpiece carriage in the machine tool. The improvement comprises storing signals corresponding to a plurality of safety positions of the workpiece carriage located within the terminal positions of the carriage in a memory device provided in the numerical control means. The safety position signals are then compared with measured position signals generated by the position determining means which correspond to the position of the workpiece carriage in the machine tool. The feed rate of the workpiece carriage is automatically reduced by the numerical control means when the safety positions are passed by the workpiece carriage as the carriage moves in a direction towards the terminal positions. The feed rate reduction is cancelled by the numerical control means, however, if a position signal is generated by the numerical control means for moving the workpiece carriage in a direction away from the terminal positions to a position within the safety positions in the machine tool.

Dependencies are inferred from the claim text.