Machine Tool Coolant Filter Clog Detection by Pump Flow Comparison
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Solution Overview
Problem
Conventional machine tools inaccurately detect filter clogging due to coolant overflow, leading to unreliable coolant circulation, as they rely solely on liquid level detection, which can result in false positives when a large amount of coolant is discharged.
Innovation Solution
A machine tool system that monitors the difference in coolant discharge and return rates over a predetermined time, using index values from discharge and collecting pumps' motor drive frequencies to determine filter clogging, and alerts the operator through a display unit when the difference exceeds a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid level detection is used to determine filter clogging, then the detection method is simple, but false positives occur when large amounts of coolant are discharged
Solution Approach 1:
The detection method is segmented into multiple independent measurement components: discharge pump motor frequency measurement, collecting pump motor frequency measurement, and differential comparison. This segmentation allows each component to be measured separately and then compared to determine actual filter clogging status, eliminating false positives from coolant overflow.
Solution Approach 2:
The system implements feedback by continuously monitoring the difference between discharge and collecting pump frequencies and using this feedback to determine filter clogging status. The control unit compares the frequency difference against predetermined thresholds and provides feedback signals to indicate actual clogging conditions, eliminating false alarms.
2Measurement precision
If coolant circulation is monitored using pump frequencies, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The motor frequencies of the discharge and collecting pumps serve as intermediary variables that indirectly reflect coolant circulation status. Instead of directly measuring coolant flow, the system measures motor frequencies as intermediaries and compares their difference to determine filter clogging, simplifying the monitoring system while maintaining precision.
Solution Approach 2:
The system replaces direct mechanical flow measurement with electrical frequency measurement of pump motors. This substitution uses electrical signals (motor drive frequencies) instead of mechanical flow sensors, improving measurement precision while avoiding the complexity of direct flow measurement systems.
Data Source
AI summary
There is provided a technique for more reliably detecting clogging of a filter with chips over conventional techniques. A machine tool that can machine a workpiece includes a storage tank; a discharge unit that discharges coolant stored in the storage tank toward chips resulting from the machining of the workpiece; a filter that removes the chips from the coolant; a collecting pump that brings the coolant back to the storage tank; a first obtaining unit that obtains a first index value indicating an amount of coolant discharged per predetermined time; a second obtaining unit that obtains a second index value indicating an amount of coolant that is brought back to the storage tank per predetermined time; and a notifying unit that notifies of an abnormality in the filter when a result of comparison of the first index value with the second index value satisfies a predetermined abnormality condition.