Machine Tool and Brake Checking Method

Abstract

A machine tool for detecting a brake failure more reliably in a mechanism that stops the rotation of a vertical shaft by at least two brakes includes a ball screw extended in a vertical direction, a driving motor that rotates the ball screw, a movable part that vertically moves along the ball screw in accordance with the rotation of the ball screw driven by the driving motor, at least two brakes that prevent a fall of the movable part while power supply to the driving motor is stopped, a brake controller that releases at least one of the at least two brakes while power supply to the driving motor is stopped, and a detector that detects presence/absence of a fall of the movable part or a fall distance of the movable part resulting from the release of the at least one brake, thereby detecting a trouble of an unreleased one of the at least two brakes.

Dependencies are inferred from the claim text.