Machine tool with a sliding screw drive
AssigneePaul Forkardt GmbH & Co. KG
InventorHubert Bald
Life of this patent
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Abstract
A machine tool having a work spindle with an electrically actuated clamping unit including a three-phase motor with a stationary stator. The motor is supplied with electricity from a control unit operating with frequency conversion, and the control unit is alternatingly also used for triggering a spindle drive motor. A sensor detects clamping force applied to a workpiece, and produces a signal used to reduce motor speed of the three-phase motor until a predetermined clamping force is achieved.
Claims23
An electrically actuated clamping device for a machine tool having a work spindle and a first motor for driving said spindle, said clamping device comprising:
- a sliding screw drive associated with and disposed coaxially relative to said spindle,
- a second motor comprising a three phase motor drivingly coupled to said screw drive, and
- a control means for continuously regulating energy supply to said second motor, said control means including frequency converter means for feeding said second motor with a three phase current comprised of a magnetizing current component and a torque-producing current component, and said control means further including a computer means for continuously adjusting both said magnetizing and torque-producing components in response to operational conditions of said second motor, and
- a sensor means for detecting an actual clamping force magnitude to produce an output signal in response thereto and to feed said output signal to said control means which, in response thereto during actuation of said clamping device to produce said clamping force, adjusts said current components after engagement of the clamping device with a workpiece, so as to reduce the speed of said second motor until a predetermined clamping force is achieved.
An electrically actuated clamping device for a lathe having a work spindle and a first motor for driving said spindle and a tailstock, said tailstock including a tailstock body axially displaceable relative to said spindle and a thrust member housed in said tailstock body and axially displaceable relative to said body against bias of a thrust-force-producing spring, a sliding screw drive having an axis parallel to said spindle and coupled to said tailstock body for axial displacement thereof, said tailstock further comprising:
- a second motor comprising a three phase motor for actuating said sliding screw drive,
- a control means for continuously regulating energy supply to said second motor which is a three phase motor, said control means including frequency converter means for feeding said second motor with a three phase current comprised of a magnetizing current component and a torque-producing current component, and said control means further including a computer means for continuously adjusting both said magnetizing and torque-producing components in response to operational conditions of said second motor, and
- a sensor means for detecting an actual thrust force magnitude to produce an output signal in response thereto and to feed said output signal to said control means which, in respone thereto, during actuation of said tailstock drive to produce said thrust force, adjusts said magnetizing and torque-producing current components ater engagement of the clamping device with a workpiece, so as to reduce the speed of said second motor until a predetermined thrust force is achieved.
Dependencies are inferred from the claim text.