Cincinnati Milacron Inc.

David A Topmiller

James E O'Bryan

John C Catanzaro

A method and apparatus for verification of the linear position of a machine element driven by a motor is provided. The actual position of the element is detected and compared to an expected position. When the two positions differ from each other by more than a predetermined tolerance value for a predetermined amount of time, an error signal is generated which deactivates the motor and generates an alarm for the machine operator. Preferably, the linear position of the axis is detected by a transducer and the expected position is determined by detecting the rotary position of the motor through the use of a resolver, which is then converted to a linear equivalent through the use of the gearing ratio. The method and apparatus can detect faulty machine conditions and thereby prevent machine malfunction and/or machine damage. Preferably, the method and apparatus are used to verify the position of machine elements in an injection molding machine.

Method and apparatus for injection molding machine control

A method and apparatus are provided for servo control of injection molding machine devices. A signal processor periodically produces analogue control signals for controlling machine mechanisms at a first loop closure interval and periodically produces digital control signals for controlling energization of machine heaters at a second loop closure interval. Values of analogue and digital control signals are determined according to control algorithms relating set point values and measured parameter values. Calculation of values of analogue control signals includes calculation of a first command value according to a first control algorithm, calculation of a second command value according to a second control algorithm and selection of the lesser of the first and second command values. Compensation for 'cold' thermocouple junctions created at the connection of remote temperature sensing thermocouple leads and the signal processor interface circuits is provided. DC output interface circuits including two stage over-current protection are provided.

Servo control for molding machine

A transducer interface circuit is provided having means for detecting loss of connection of a transducer to the interface circuit. The interface circuit is intended for use with a transducer providing an output between two electrical poles of opposite polarity. Differential inputs of a differential amplifier are connected to the transducer poles. A bias current source is provided proximate the amplifier at least at one input, and the other input is connected to ground. Loss of connection between the transducer and amplifier results in saturation of the amplifier output.

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Ft. Wright, KY, United States of America

David A Topmiller