Method and apparatus for cutting filter materials

Abstract

A method of cutting filter materials in the tobacco industry wherein a filter material in the form of filter rods is fed to rotary knife unit, the filter rods are cut into segments by means of rotary knives pressing the filter rods against a guiding jacket characterised in that the rotary knives are cooled in the area behind the guiding jacket.

1 . A method of cutting filter materials in the tobacco industry wherein:
 by means of a drum conveyor provided on its circumference with flutes the filter material in the form of filter rods is fed to a rotary knife unit;   the filter rods are cut into segments in the flutes of the drum conveyor in an area beneath a filter rod guiding jacket by means of rotary knives,   characterised in that   the rotary knives are cooled in the area behind the guiding jacket.   
     
     
         2 . The method as in  claim 1  characterised in that the rotary knives are cooled to a temperature in the range between 5 and 25° C. 
     
     
         3 . The method as in  claim 1  characterised in that the rotary knives are cooled with a cooling medium selected from a group consisting of: compressed air, water, and liquid nitrogen. 
     
     
         4 . The method as in  claim 1  characterised in that the rotary knives are cooled with a cooling medium in a closed cycle. 
     
     
         5 . The method as in  claim 1  characterised in that the rotary knives are cooled with a cooling medium in an open cycle. 
     
     
         6 . An apparatus for cutting filter materials in the tobacco industry comprising:
 a rotary knife unit provided with a filter rod guiding jacket for guiding filter rods conveyed in flutes of a drum conveyor,   characterised in that   the rotary knife unit comprises rotary knives, and   in a space behind the guiding jacket a cooling unit lowering the temperature of the rotary knives by means of a cooling medium is situated.   
     
     
         7 . The apparatus as in  claim 6  characterised in that the cooling unit comprises at least one cooling medium blowing nozzle for each knife. 
     
     
         8 . The apparatus as in  claim 6  characterised in that the cooling unit comprises two cooling medium blowing nozzles on two sides of a knife. 
     
     
         9 . The apparatus as in  claim 7  characterised in that the cooling medium nozzles are situated substantially perpendicular to the knife surface. 
     
     
         10 . The apparatus as in  claim 7  wherein the rotary knives have cutting edges, characterised in that the cooling medium nozzles are situated just at the cutting edges. 
     
     
         11 . The apparatus as in  claim 6  characterised in that the cooling unit operates in an open system. 
     
     
         12 . The apparatus as in  claim 6  characterised in that the cooling unit operates in a closed system. 
     
     
         13 . The apparatus as in  claim 6  characterised in that the cooling unit is a unit for cooling with air, water or liquid nitrogen. 
     
     
         14 . The apparatus as in  claim 6  characterised in that a temperature sensor is assigned at least to one knife. 
     
     
         15 . The apparatus as in  claim 6  characterised in that the rotary knife unit comprises rotary knives of tungsten carbide. 
     
     
         16 . The method as in  claim 2  characterised in that the rotary knives are cooled to a temperature in the range between 15 and 25° C. 
     
     
         17 . The method as in  claim 16  characterised in that the rotary knives are cooled to a temperature in the range between 20 and 25° C.