Patent ID: 7454935

Claim:
A method for ensuring the use of a machine tool having a first tool part carrying out working movements in a direction of a second tool part so that during these working movements, an open gap between the first tool part and one of the second tool part and a workpiece to be machined, is gradually closed, the method comprising: monitoring a three-dimensional protected field between the tool parts using an optoelectronic sensor; transmitting at least one light ray along the open gap by means of a transmitter device and detecting the at least one light ray by means of a receiver device; triggering a switch-off process to stop the first tool part when the sensor detects an interruption of the at least one light ray; wherein the switch-off process comprises: maintaining an extent (C 1 ) of the protected field in a direction of the working movement smaller than an extent (E 1 ) of the open gap, upon commencing working movement of the first tool part, wherein the protected field initially follows the working movement of the first tool part; continuously reducing the extent (C 2 ) of the protected field and holding the protected field in the center of the open gap, upon continued working movement; maintaining the extent (C 3 ) of the protected field and holding the protected field in the center of the open gap upon further continued working movement; and deactivating the sensor.