Cincinnati Milacron Inc.

James D Suer

R William Kneifel, Ii

Paul A Zaffiro

A machine with a movable element, such as a machine tool and its spindle carrier, that is powered by a motive means to move the element is provided with a counterbalancing system having at least two counterforce means operably connected to the movable element for exerting a counterbalance force on the movable element in opposition to the first force and wherein a first one of the counterforce means has a controllable servomotor means. The control means controls the servomotor means so as to cause the counterbalancing system to exert a substantially constant counterbalance force on the movable element in opposition to the first force. The second one of the counterforce means may be a hydraulic means having a hydraulic cylinder operably connected to an accumulator and a hydraulic piston operably disposed in the cylinder and connected to the movable-element. The control means has a load sensor to sense a load on the movable element and convert the sensed load into a signal used to control the servomotor means which may be a torque controlled electric servomotor for controlling the vertical travel of a spindle carrier in machine tool.

Counterbalance system

A method and apparatus are disclosed for reducing the cross-coupled movement in a member of a CNC machine caused by movement in another member of the machine through the structural dynamics of the machine. The method includes receiving the discrete position commands for a member oriented in one axis of movement for the machine, transforming the discrete position commands to attenuate frequency components that contribute to the movement coupled through the structural dynamics of the machine, and generating velocity commands from the transformed discrete position commands to control the servos that drive the members. The discrete position command transform is preferably a second order filter that implements the transfer functions of a digital notch filter and digital low pass filter. The second order filter that transforms the discrete position commands is implemented in a digital computer by state variable difference equations.

Method and apparatus for reducing cross-coupled movement through the

There is shown and described herein a D.C. motor control circuit which provides both overheat protection and current overload protection. The circuit provides for continued motor operation in short-duty cycles while operating in a current overloaded condition so long as the temperature of the motor has not exceeded a predetermined level past which damage might be expected.

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Cincinnati, OH, United States of America

James D Suer