Machine tool analysis device and method

Abstract

The invention relates to a device and method for analysis of a tool 50 e.g. used on a machine tool. A tool detector 5 includes a light emitter 12 and a light receiver 34 . Tool 50 when progressed into a beam 20 of light emitted from the emitter 12 will cause a signal from the receiver to change. Circuitry 32 includes a digital signal processor which processes the signal from the receiver and produces an output only if the signal conforms to a predetermined condition. Preferably this predetermined condition could be e.g. a characteristic shape of the signal from the receiver, a change in a value derived from a succession of such signals or a change in the minimum or maximum values of a succession of signals from the receiver.

1 . A method of analyzing a rotating tool, comprising the steps of: 
 (i) taking a light emitter and a light receiver,    (ii) passing a light beam from the light emitter to the light receiver, wherein the light receiver produces a signal indicative of the amount of light being received,    (iii) moving a rotating cutting tool having at least one tooth through the light beam,    (iv) determining characteristic deviations in the signal output by the light receiver as the at least one tooth of the rotating cutting tool interrupts the light beam,    (v) comparing a series of the characteristic deviations determined in step (iv) to a predetermined pattern; and    (vi) issuing a trigger signal when the series of characteristic deviations conform to the predetermined pattern.    
   
   
       2 . A method according to  claim 1  wherein each of the characteristic deviations comprise at least one of a maxima and a minima in the signal.  
   
   
       3 . A method according to  claim 1  wherein each of the characteristic deviations comprise a minima followed by a maxima followed by a minima.  
   
   
       4 . A method according to  claim 1  wherein a characteristic deviation is produced during each rotation of the rotating cutting tool.  
   
   
       5 . A method according to  claim 1  wherein step (v) comprises fitting the series of characteristic deviations to a polynomial expression.  
   
   
       6 . A method according to  claim 1  comprising the step of using temporal changes in a series of characteristic deviations to determine the position of the cutting tool relative to the beam.  
   
   
       7 . A method according to  claim 6  comprising the step of moving the cutting tool relative to the light beam at a known velocity such that, when the cutting tool reaches a predetermined position relative to the light beam, cutting tool geometry can be determined.  
   
   
       8 . A method according to  claim 1  comprising the step of issuing the trigger signal when the cutting tool reaches a predetermined position relative to the light beam.  
   
   
       9 . A method according to  claim 1  comprising the steps of rotating the cutting tool with constant angular velocity and determining the diameter of the cutting tool.  
   
   
       10 . A method according to  claim 1  wherein step (v) comprises the step of determining how many characteristic deviations that conform to the predetermined pattern are present in a predetermined time period and step (vi) comprises issuing the trigger signal when a predetermined number of such characteristic deviations are present in the predetermined time period.  
   
   
       11 . A method according to  claim 1  comprising the step of determining the position of the edge of the cutting tool.  
   
   
       12 . A method according to  claim 1  in which the rotating cutting tool provided in step (iii) comprises at least a first tooth and a second tooth, wherein step (iv) comprises determining first characteristic deviations in the signal output by the light receiver as the first tooth interrupts the light beam and second characteristic deviations in the signal output by the light receiver as the second tooth interrupts the light beam.  
   
   
       13 . A method according to  claim 12  wherein step (v) comprises comparing a series of the first characteristic deviations to a first predetermined pattern and comparing a series of the second characteristic deviations to a second predetermined pattern.  
   
   
       14 . A method according to  claim 1  in which any deviations in the signal are ignored that do not have an expected characteristic deviation.  
   
   
       15 . A method according to  claim 1  wherein step (iii) comprises moving the rotating cutting tool into the light beam and step (iv) comprises determining the characteristic deviations as the cutting tool enters the light beam.  
   
   
       16 . A method according to  claim 1  wherein step (iii) comprises moving the rotating cutting tool out of the light beam and step (iv) comprises determining the characteristic deviations as the cutting tool leaves the light beam.  
   
   
       17 . A method of analyzing a rotating tool, comprising the steps of; 
 (i) taking a light emitter and a light receiver,    (ii) passing a light beam from the light emitter to the light receiver, wherein the light receiver produces a signal indicative of the amount of light being received,    (iii) moving a rotating cutting tool having at least one tooth into said light beam,    (iv) determining at least one of minimum values and maximum values in the signal output by the light receiver as the at least one tooth of the rotating cutting tool interrupts the light beam,    (v) comparing a plurality of said at least one of minimum values and maximum values determined in step (iv) to a predetermined condition, and    (vi) issuing a trigger signal when said at least one of minimum values and maximum values conform to said predetermined condition.    
   
   
       18 . A tool analysis device for analyzing a rotating cutting tool, comprising; 
 a light emitter for emitting a beam of light,    a light detector for receiving light from the light emitter and producing a signal indicative of the amount of light received,    a processor for analyzing the signal, the processor determining characteristic deviations in the signal and comparing a series of such characteristic deviations to a predetermined pattern,    wherein the processor issues a trigger signal when the series of characteristic deviations conform to the predetermined pattern.    
   
   
       19 . A device according to  claim 18  wherein the processor issues the trigger signal when the cutting tool reaches a predetermined position relative to the light beam.  
   
   
       20 . A tool analysis device for analyzing a rotating cutting tool, comprising; 
 a laser for emitting a beam of light,    a photodiode for receiving light from the laser and producing a voltage signal indicative of the amount of light received,    an analogue-to-digital converter for converting the voltage signal into a numerical representation of the voltage signal,    a digital signal processor for receiving and analyzing the numerical representation of the voltage signal, the digital signal processor determining characteristic voltage deviations in the voltage signal and comparing a series of such characteristic voltage deviations to a predetermined pattern,    wherein the digital signal processor issues a trigger signal when the series of characteristic deviations conform to the predetermined pattern.