Method and sensor device for monitoring a laser machining operation to be performed on a work piece as well as laser machining head with a sensor device of the kind

Abstract

The invention concerns a method which can be carried out with a sensor device, for monitoring a laser machining operation to be performed on a work piece, in which for quality assurance with a local-resolution receiver assembly, a given field of observation is selected in the region of the interaction zone between laser beam and work piece, in which radiation coming from the selected field of observation is detected with a radiation-sensitive receiver which delivers an electrical signal corresponding to the detected radiation, in which the electrical signal is filtered in a signal processing circuit in order to detect rapid and/or short, fault-related changes in intensity of the detected radiation, and in which the filtered electrical signal for the detection of faults during the laser machining operation.

1 . A method for monitoring a laser machining operation to be performed on a work piece, in which the following steps are performed for quality assurance: 
 selection of a given field of observation in the region of the interaction zone between laser beam and work piece,    detection of radiation coming from the selected field of observation with a radiation-sensitive receiver which delivers an electrical signal corresponding to the detected radiation,    filtering of the electrical signal in order to be able to detect rapid and/or short, fault-related changes in intensity of the detected radiation, and    evaluation of the filtered electrical signal for the detection of faults during the laser machining operation.    
     
     
         2 . The method according to  claim 1 , characterized in that for the selection of a given field of operation, the interaction zone is projected onto a stop arranged in front of the radiation-sensitive receiver.  
     
     
         3 . The method according to  claim 1 , wherein a spectral sensitivity of the radiation-sensitive receiver is fixed according to the selected field of observation.  
     
     
         4 . The method according to  claim 1 , wherein the electrical signal is subjected to high-pass filtering.  
     
     
         5 . The method according to any of the preceding claims, wherein the filtered electrical signal is compared with stored values of a perfect machining operation in order to detect smaller faults such as small splittings or splashed as well as small holes.