Apparatus and method for measuring small increases in machine tool drive motor power
AssigneeGrowth Financial AG
InventorsIvan Dzombak, William A. Kline
Life of this patent
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Abstract
An apparatus and method for measuring the electrical load on a motor driven tool operating in a cycle having idle and cutting or machining states. The electrical power is continuously measured and an average power value is established during the idle state of at least one cycle and used as an offset subtracted from the measured electrical power values to generate an output proportional to the incremental power drawn by the cutting tool during the cutting state. The offset value is recalculated at the start of each new cycle and/or just prior to the commencement of a cutting operation by a tool. At least one filter and/or an amplifier are used to improve the signal-to-noise ratio of the output signal.
Claims15
A method for measuring the electrical power drawn by a cutting tool drive motor in a single operating cycle having idle and cutting states, the method comprising the steps of:
- measuring the power load on the drive motor continuously during each idle and cutting state;
- offsetting the measured electrical power values during the cutting state with the measured power values during the idle state to yield the incremental power load attributable to the cutting tool on the motor during the cutting state;
- amplifying the incremental power load by a variably selectable gain between two and 800;
- setting the variably selectable gain by:
- providing a plurality of settable switches outputting a combined binary code to a processor;
- and,
- providing the processor accessing a lookup table containing gain values corresponding to the binary code defined by the plurality of switches;
- and
- filter the amplified incremental power load by a median filter to generate an output signal.
An apparatus for measuring the electric power load on a tool drive motor in a single operating cycle including idle and cutting states, the apparatus comprising;
- means for measuring the electrical power load on the motor continuously during one complete operating cycle;
- means for calculating an offset value corresponding to the measured electrical power during the idle state of the operating cycle;
- means for computing incremental power load adjusted by the offset value, attributable to the incremental load power drawn by the cutting tool during the cutting state;
- means for setting a variably selectable gain including:
- a plurality of settable switches outputting a combined binary code to a processor;
- and,
- the processor accessing a lookup table containing gain values corresponding to the binary code defined by the plurality of switches;
- means for amplifying the incremental power load by the variably selectable gain of between two and 800;
- and
- means for filtering the amplified incremental power load by a median filter to form an amplified output signal.
Dependencies are inferred from the claim text.