Kearney & Trecker Corporation

John J Schachte

Edward E Kirkham

Frank Zankl

Richard E Stobbe

Earl R Lohneis

In apparatus for controlling the speed and torque of a multiphase a.c. motor in accordance with digital control signals, a first regulation circuit regulates the frequency of the a.c. electrical signal applied to the motor and another regulation circuit regulates the voltage of the a.c. signal. Both regulation circuits are controlled by digital control signals in a series of discrete steps over a range of control values and the control signals are supplied periodically to the regulation circuits. The speed and torque are controlled in accordance with an algorithm relating speed and torque to the frequency and voltage of the source of electric power which is applied to the motor, calculated by computing apparatus on a periodic basis. In one embodiment the position of the magnetic flux of the stator is controlled directly.

A.C. motor control apparatus and method

This invention relates to a greatly simplified workpiece changer mechanism in combination with a simplified tool storage and changing mechanism for a machine tool. To accomplish this, a rotatable work carrying spindle is adapted to support a workpiece for selective rectilinear movement relative to an associated rotary cutting tool, and to support the same workpiece for selective rotational movement relative to a rectilinearly movable cutting tool carried by the same spindle. The work receiving spindle is mounted in spaced apart relationship to a storage support adapted to releasably carry a workpiece for selective interchange with a workpiece carried by the work spindle. To effect a selective interchange of workpieces between the work spindle and the storage support, a work transfer arm is pivotally supported between the work spindle and the work support. At its opposite ends, the work transfer arm is provided with oppositely extending openings respectively adapted to receive work support rings of like size and configuration. The arrangement is such that the transfer arm pivots 90.degree. in one direction for moving the oppositely disposed openings presented thereby into clamping engagement with the workpieces respectively carried by the work spindle and the storage member. Automatic clamping means respectively associated with the work receiving openings are disposed to be actuated into clamped engagement with the workpieces for retaining them in predetermined angularly clamped positions during the interchange. Next, the work spindle and support member are retracted from engagement with the respective work supports, and the transfer arm rotated through another 180.degree. for respectively realigning the work supports in interchanged position with the work spindle and the support member respectively. The latter are moved forward into clamping reengagement with the now interchanged work supports. The transfer arm clamping means are then released and the transfer arm pivotally moved 90.degree. in the opposite direction to return the transfer arm to its central parked position. To accelerate controlled movement of the work transfer arm, a velocity control system is provided in combination with automatic clamping means for retaining work support rings in clamped engagement within the oppositely disposed openings provided in the transfer member.

Unitary work changer for a machining center

Method of controlling an A.C. motor

In apparatus for controlling the speed and torque of a multiphase a. c. motor in accordance with digital control signals, a first regulation circuit regulates the frequency of the a. c. electrical signal applied to the motor and another regulation circuit regulates the voltage of the a.c. signal. Both regulation circuits are controlled by digital control signals in a series of discrete steps over a range of control values and the control signals are supplied periodically to the regulation circuits. The speed and torque are controlled in accordance with an algorithm relating speed and torque to the frequency and voltage of the source of electric power which is applied to the motor, calculated by computing apparatus on a periodic basis. In one embodiment the position of the magnetic flux of the stator is controlled directly.

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West Hartford, CT, United States of America

John J Schachte