Machine tool with fault detection
First Claim
Patent Images
1. A machine tool comprising:
- a cutting tool;
a spindle which holds said cutting tool;
a drive unit arranged to drive said spindle so that said cutting tool cuts a workpiece and to drive said spindle in a reverse direction so that said cutting tool retracts from said workpiece; and
a control unit arranged to detect a value representing a torque applied on said spindle and to compare said value with a predetermined threshold thereby to determine if a fault has occurred;
wherein said control unit detects said value when said drive unit stops said spindle in a state that said cutting tool is acting on said workpiece with applying the torque on said spindle to keep the engagement of the cutting tool with said workpiece.
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Abstract
A machine tool includes a spindle having a cutting tool for cutting a workpiece. For fault detection, a control unit of the machine tool detects a value representing a torque applied on the spindle while the spindle is stopped in a state the cutting tool is engaged with the workpiece. The control unit further compares the detected value (representing a torque) with a predetermined threshold thereby to determine that a fault has occurs. Since the detection of the value representing a torque is performed while the spindle is stopped, the detection is free from the effects of acceleration or deceleration of the spindle.
40 Citations
22 Claims
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1. A machine tool comprising:
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a cutting tool; a spindle which holds said cutting tool; a drive unit arranged to drive said spindle so that said cutting tool cuts a workpiece and to drive said spindle in a reverse direction so that said cutting tool retracts from said workpiece; and a control unit arranged to detect a value representing a torque applied on said spindle and to compare said value with a predetermined threshold thereby to determine if a fault has occurred; wherein said control unit detects said value when said drive unit stops said spindle in a state that said cutting tool is acting on said workpiece with applying the torque on said spindle to keep the engagement of the cutting tool with said workpiece. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for detecting a fault on a cutting tool during machining a workpiece with said cutting tool, said cutting tool being provided on a spindle, said method comprising the steps of:
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rotating said spindle with a torque required to resist a reactive force from said workpiece, so that said cutting tool cuts said workpiece; stopping said cutting tool in a state that said cutting tool is engaged with said workpiece, while keeping applying said torque on said spindle; reading a value representing said torque applied on said cutting tool; comparing said value with at least one predetermined threshold; and determining if a fault has occurred, based on a result of said comparing step. - View Dependent Claims (21, 22)
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Specification