Device and process for the precision measurement of the length of thread wound onto a bobbin

Abstract

Process for measuring the length of the yarn wound onto a bobbin which, at discreet intervals, determines the length of yarn wound in a tangential direction, the length of yarn wound in an axial direction, combining them to obtain the precise partial length wound spirally onto the bobbin at each interval and integrating the partial lengths progressively indicated during the advancement of the bobbin to obtain the overall length.

1 . A process for the measuring of the length of the yarn wound onto a bobbin characterized by the sequence of the following steps, effected at discreet measuring intervals of the winding and for each interval: 
 determination of the length of yarn m fy  wound in a tangential direction,    determination of the length of yarn m fx  wound in an axial direction,    composition of the two lengths of yarn wound in a tangential and axial direction to obtain the partial length m f  spirally wound onto the bobbin at each interval progressively indicated,    integration of the partial lengths m f  progressively indicated during the formation of the bobbin to obtain the length progressively wound.    
     
     
         2 . The process for measuring of length of yarn according to  claim 1 , characterized by the following steps: 
 determination of the length of yarn m fy  wound in a tangential direction, on the basis of the measurement of the number of revs of the bobbin ΔN r  in the interval and the bobbin diameter revealed φ r  during the same interval, according to the formula:      m fy =ΔN r πφ r      determination of the length of yarn m fx  wound in axial direction in the same interval on the basis of the measurement of the number of revs ΔN c  of the cylinder in the interval, according to the formula:        m   fx   =ΔN   c   T/N   e      T being the traversing run and N e  is the number of helixes of the cylinder,    composition of the two tangential and axial components according to the formula:        m   f =[(Δ N   c   T/N   e ) 2 +(Δ N   r πφ r ) 2 ] 1/2      integration of the partial lengths m f  progressively indicated during the formation of the bobbin.    
     
     
         3 . The process for measuring the length of yarn according to  claim 1 , characterized in that the discreet measuring intervals refer to the progressive number of revs of the activation cylinder from the start of the bobbin.  
     
     
         4 . The process for measuring the length of yarn according to  claim 2 , characterized in that the diameter φ r  of the bobbin is measured in the axial coordinate of the barycentre of the bobbin.  
     
     
         5 . The process for measuring the length of yarn according to  claim 2 , characterized in that the measurement of the diameter of the bobbin φ r  is effected with a distance sensor, assembled integrally onto the bobbin-holder arm.  
     
     
         6 . The process for measuring the length of yarn according to  claim 5 , characterized in that the measurement of the diameter of the bobbin φ r  is effected with a reflection laser sensor.  
     
     
         7 . The process for measuring the length of yarn according, to  claim 5 , characterized in that the measurement of the diameter of the bobbin φ r  is effected in a point suitably positioned at a due distance from the supporting line on the cylinder, so that the deformation of the surface of the bobbin does not influence the measurement of the diameter of the bobbin.  
     
     
         8 . The process for measuring the length of yarn according to  claim 2 , characterized in that the measurement of the diameter of the bobbin φ r  is effected by detecting the geometrical position of the arm itself with respect to the activation cylinder.  
     
     
         9 . The process for measuring the length of yarn according to  claim 8 , characterized in that the detection of the geometrical position of the arm with respect to the activation cylinder is effected with an angular potentiometer which provides the measurement of the rising of the bobbin-holder arm ( 11 ) with respect to the activation cylinder ( 16 ).  
     
     
         10 . Device for measuring the length of the yarn wound onto a bobbin comprising the following components: 
 a progressive revolution counter ( 31 ) for the activation cylinder of the bobbin, 
 a progressive revolution counter ( 30 ) for the bobbin,  
 a measurer ( 20 ) of the diameter of the bobbin φ r .  
   
     
     
         11 . The device for measuring the length of the yarn wound onto a bobbin according to  claim 10 , characterized in that the revolution counter devices ( 30 ,  31 ) are produced as magnetic disks integral with the rotating part, equipped with N-S magnetic poles associated with a Hall-effect probe positioned for revealing the passage of said rotating poles.  
     
     
         12 . The device for measuring the length of the yarn wound onto a bobbin according to  claim 10 , characterized in that the measurer ( 20 ) of the diameter of the bobbin φ r  is a distance sensor firmly positioned on the bobbin-holder arm.  
     
     
         13 . The device for measuring the length of the yarn wound onto a bobbin according to  claim 12 , characterized in that the measurer ( 20 ) of the diameter of the bobbin φ r  is a reflection laser sensor.  
     
     
         14 . The device for measuring the length of the yarn wound onto a bobbin according to  claim 10 , characterized in that the distance measurer ( 20 ) is suitable for revealing the diameter of the bobbin φ r  ( 10 ) in a point duly distant from the supporting line on the cylinder ( 16 ), so that the deformation of the surface of the bobbin does not influence the measurement of the diameter of the bobbin.