Machine tool with fault detection
AssigneeBrother Kogyo Kabushiki Kaisha
InventorsMasayuki Iwai, Katsunori Tsutsui
Life of this patent
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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.
Claims22
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.
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:
- 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.
Dependencies are inferred from the claim text.