Malfunction detection system for intermittent events

A method for monitoring the operation of an industrial machine of the type (i) comprising a machine controller adapted to stop said industrial machine in response to a machine stop signal, (ii) characterized by repetitive machine cycle operation and the intermittent occurrence of events of a predetermined type, and (iii) requiring the occurrence of one of said predetermined type of events within a preselected number greater than one of said machine cycles following the next preceding one of said predetermined type of events for continuous and safe machine operation;

• said method comprising the steps of:
• (1) providing a system comprising:
• sensor means for detecting the occurrence of said predetermined type of events during the operation of said industrial machine, said sensor means being positioned relative to said industrial machine in sensing relation to the expected location of said predetermined type of events and including means for generating a signal in response to each detection of a predetermined type of event;
• counter means for counting said repetitive machine cycles of said industrial machine, said counter means being associated with said industrial machine and being resettable to a first preselected count in response to a reset signal;
• reset signal generating means connected to said sensor means and to said counter means, said reset signal generating means being responsive to said signals generated by said sensor means and being adapted to convey a reset signal to said counter means whenever the occurrence of one of said predetermined type of events is detected by said sensor means;
• and
• machine stop signal generating means connected to said counter means and to said machine controller, said machine stop signal generating means being adapted to transmit a machine stop signal to said machine controller whenever said counter means reaches a second preselected count;
• (2) starting said industrial machine and said counter means;
• and
• (3) operating said system in conjunction with said industrial machine such that:
• (a) said reset signal generator will convey a reset signal to said counter means whenever said sensor means detects the occurrence of one of said predetermined type of events;
• and
• (b) said machine stop signal generating means will convey a stop signal to said machine controller so as to stop said industrial machine when said counter reaches said second preselected count.

A system for monitoring the operation of an industrial machine of the type (i) comprising a machine controller adapted to stop said industrial machine in response to a machine stop signal, (ii) characterized by repetitive machine cycle operation and the intermittent occurrence of events of a predetermined type, and (iii) requiring the occurrence of one of said predetermined type of events within a preselected number greater than one of said machine cycles following the next preceding one of said predetermined type of events for continuous and safe machine operation;

• said system comprising:
• sensor means for detecting the occurrence of said predetermined type of events during the operation of said industrial machine, said sensor means being adapted to be positioned relative to said industrial machine in sensing relation to the expected location of said predetermined type of events and including means for generating a signal in response to each detection of a predetermined type of event;
• counter means for counting said repetitive machine cycles of said industrial machine, said counter means being associated with said industrial machine and being resettable to a first preselected count in response to a reset signal;
• reset signal generating means connected to said sensor means and to said counter means, said reset signal generating means being responsive to said signals generated by said sensor means and being adapted to convey a reset signal to said counter means whenever the occurrence of one of said predetermined type of events is detected by said sensor means;
• and
• machine stop signal generating means connected to said counter means and to said machine controller, said machine stop signal generating means being adapted to transmit a machine stop signal to said machine controller whenever said counter means reaches a second preselected count;
• wherein said industrial machine is a punch press of the type comprising a die and a punch, said punch being adapted for intermittent association with said die for sequentially forming punched out portions from a piece of stock material, wherein said die includes a channel having an entrance, an exit and the capacity to contain a preselected maximum number of said punched out portions, said channel being adapted to receive said sequentially punched out portions of said stock material at said entrance during the operation of said industrial machine;
• wherein said predetermined type of event comprises the ejection of said punched out portions from said channel exit;
• and further wherein said sensor means is located adjacent said channel exit so that said punched out portions of said stock material leaving said die through said channel exit are detected by said sensor means.