MACHINE TOOL HAVING INSPECTION FUNCTION FOR DETERIORATED STATE OF SPINDLE

摘要

In order to make it possible to inspect a deteriorated state of a spindle incorporated in a machine tool without disassembling the machine tool, a command for speed V0 is output to the spindle and, when the rotating speed of the spindle reaches V0, power of a spindle motor is interrupted and a timer is started. The spindle continues to rotate with inertia while decelerating. Time T clocked by the timer when the spindle speed decreases to zero is read. When time T is outside a range between the upper and lower limits, the spindle is in the deteriorated state, and an alarm is output. When time T is not greater than the lower limit, the spindle and a bearing of the spindle are deteriorated and friction resistance increases. When time T is larger than the upper limit, oil holding force of grease of the bearing is deteriorated.

主权项

1. A machine tool having an inspection function for a deteriorated state of a spindle, the machine tool including a spindle configured to hold a tool that machines work and rotatably supported by a bearing, a motor configured to drive the spindle, and an encoder configured to measure a rotation angle position of the spindle or the motor,
the machine tool comprising: speed calculating unit for calculating rotating speed of the spindle or the motor from an output of the encoder; unit for rotating the spindle or the motor at predetermined speed and thereafter interrupting power of the motor to rotate the spindle with inertia; clocking unit for measuring, after the power of the motor is interrupted, an inertial rotation time until the rotating speed calculated by the speed calculating unit reaches set target speed; determining unit for setting the time measured by the clocking unit as a value to be compared with a threshold and determining whether the value is equal to or smaller than a threshold set in advance; and alarm output unit for outputting an alarm when the determining unit determines that the value is larger than the threshold.