Tool failure detection utilizing frequency derived, pre-characterization templates

A method utilizing a frequency derived, pre-characterization template for detecting a tool failure from one or more spindles on a machine tool comprising the steps of:

• securing one or more pre-characterization templates having one or more frequency ranges each representing machine tool failure with said one or more templates being derived from a frequency signature trace generated from an impact applied when the machine tool is not in operation;
• placing the templates on a controller coupled to the machine tool;
• placing one or more vibration sensors near the spindle for generating electrical signals responsive to tool vibration;
• generating a frequency signature trace from said electrical signals;
• comparing a template readings with the frequency signature trace generated from the vibration sensor during machine tool operation;
• and then
• generating an alarm when high level vibrations are detected and the frequency ranges of the pre-characterization template and the frequency signature trace of the machine tool during machine operation are substantially similar indicating a machine tool failure.

A system for generating a frequency derived, pre-characterization template for detecting a tool failure in one or more tool/tool holder/spindles in a machine tool during its cycle of operation, the system comprising:

• a tool holder mounted in a spindle of the machine tool for holding a tool;
• an impactor for striking the tool for generating a simulated tool failure vibration when the machine tool is not in operation;
• at least one vibration sensitive sensor mounted near the spindle and responsive to said simulated tool failure vibration for generating an electrical signal representing sensed vibration;
• a computing system operatively coupled to the machine tool and responsive to said electrical signal, said computing system having:
• a signal conditioner for conditioning said electrical signal representing the sensed vibration;
• a low pass filter operatively coupled to said signal conditioner for filtering the electrical signal;
• a digitizer operatively coupled to said filter for continuously digitizing said filtered electrical signal during the operation of machine tool for creating a digitized data signal;
• a fast Fourier transform algorithm for continuously transforming said digitized data signal to a frequency domain and generating a frequency signature trace continuously during the operation of the machine tool;
• and
• memory locations responsive to said transform algorithm for storing said frequency signature trace;
• and
• a frequency template generator responsive to said frequency signature trace for generating an operator-readable pre-characterization template of said tool/tool-holder/spindle failure.

A monitoring system utilizing a frequency derived, pre-characterization templates for detecting a tool failure from one or more spindles on a machine tool comprising:

• a vibration sensor detecting vibrations from the one or more spindles on the machine tools;
• a processor receiving the output of the vibration sensor and creating frequency domain data for comparing with the pre-recorded pre-characterization templates from an induced vibration of the tool on the machine tool when the machine tool is not in operation, the templates having one or more frequency ranges indicating machine tool failure;
• a frequency and a time signature trace generator responsive to the output of the vibration sensor for generating frequency and time domain signals representative of the tool;
• comparators for comparing the frequency and time domain vibration signatures with the respective frequency and time domain thresholds and templates for indication of tool failure.