Tool monitoring system

A tool monitoring system for detecting a failure of a tool employed in a tool machine, comprising

• artificial signal generating means for generating a predetermined artificial tool failure signal simulating the acoustic emission signal obtained in an actual failure of the tool,
• acoustic emission transducing means adapted to be mounted at least temporarily during a setting mode on the tool machine near the tool and driven by said artificial signal generating means for applying said artificial tool failure signal to the tool machine,
• acoustic emission sensing means mounted on the tool machine near the tool so as to receive, in a setting mode of said system where said transducing means is mounted on the machine, said applied artificial tool failure signal form said acoustic emission transducing means through the tool machine and to receive in a monitoring mode of said system where the tool is operated, an actual tool failure signal if said tool fails, said acoustic emission sensing means converting said artificial signal or an actual tool failure signal into an electrical signal;
• and
• signal processing means responsive to the electrical signal generated by said acoustic emission sensing means and, in said setting mode of said system, for adjusting a characteristic of said electrical signal for later detection of a tool failure signal, said signal processing means being responsive to said electrical signal generated by said acoustic emissions sensing means, in a monitoring mode of said system, for detecting a failure of said tool, said signal processing means comprising:
• amplying means for adjusting in said setting mode a magnitude of said electrical signal fed from said acoustic emission sensing means to an optimum level reflecting a position of said acoustic emission transducing means;
• storage means for storing an optimum amplification degree of said amplifying means at which a magnitude of said electrical signal is adjusted to said optimum magnitude;
• setting means for, in said monitoring mode of said system where said tool is operated, setting an amplification degree of said amplifying means to said optimum amplification degree stored in said storage means;
• and
• means responsive to an output of the amplifying means during said monitoring mode for determining the existence of a tool failure.