Cut off apparatus for cutting off corrugated fiberboard web

Abstract

In a cut off apparatus, torque necessary for cutting band-like paper is properly distributed to both of the preceding motor and the following motor, thereby making it possible to accurately cut the band-like paper. Specifically, when the band-like paper is cut, the preceding knife and the following knife are given a specified amount of torque in the direction in which the preceding knife and the following knife are pressed against each other, by means of the preceding knife driving motor and the following knife driving motor.

1 - 18 . (canceled) 
     
     
         19 . A cut off apparatus for cutting off a corrugated fiberboard web, said apparatus comprising:
 a preceding knife cylinder having, on a peripheral surface thereof, a preceding helical knife;   a following knife cylinder having, on a peripheral surface thereof, a following helical knife for cutting off the corrugated fiberboard web in cooperation with the preceding knife;   a preceding gear attached at one of axially opposite ends of the preceding knife cylinder;   a following gear attached at one of axially opposite ends of the following knife cylinder;   a preceding drive gear which has a meshing engagement with said preceding gear;   a following drive gear which has a meshing engagement with said following gear;   a preceding knife driving motor for rotationally driving said preceding drive gear;   a following knife driving motor for rotationally driving said following drive gear, said following knife driving motor having the same rated capacity as that of said preceding knife driving motor; and   a cut off control device for individually controlling said preceding knife driving motor and said following knife driving motor;   said control device comprising:   a speed pattern generator, to which a feeding speed of the corrugated fiberboard web and a sheet length to be cut off is to be input, for generating rotational speed patterns of the preceding knife driving motor and the following knife driving motor based on the input feeding speed and the input sheet length to be cut off and for outputting a speed instruction value;   a comparator for comparing the speed instruction value from said speed pattern generator with a detected speed of the preceding knife driving motor or the following knife driving motor;   an instruction torque computing unit for computing rotational torque instruction values for the preceding knife driving motor and the following knife driving motor based on a signal from said comparator;   a cutting torque computing unit for computing cutting torque of the preceding knife driving motor and the following knife driving motor;   a to-be-given torque pattern generator for distributing the cutting torque sent from said cutting torque computing unit, generating a to-be-given torque pattern based on the feeding speed of the corrugated fiberboard web and the sheet length to be cut off, and outputting a to-be-given torque instruction value;   an instruction torque subtractor unit for subtracting the to-be-given torque instruction value, output from said to-be-given torque pattern generator, from the rotational torque instruction value computed by said instruction torque computing unit;   a preceding power amplifier for controlling the preceding knife driving motor based on a computation result obtained by said instruction torque subtractor;   an instruction torque adder for adding the rotational torque instruction value, computed by said instruction torque computing unit, to the to-be-given torque instruction value computed by said to-be-given torque pattern generator; and   a following power amplifier for controlling the following knife driving motor based on a computation result obtained by said instruction torque adder.   
     
     
         20 . The cut off apparatus as set forth in  claim 19 , wherein said cutting torque computed by said cutting torque computing unit has a cutting torque value necessary for cutting off the corrugated fiberboard web, said cutting torque value being based on a basis weight of the corrugated fiberboard web and the input feeding speed. 
     
     
         21 . The cut off apparatus as set forth in  claim 19 , wherein said cutting torque computed by said cutting torque computing unit is large enough to resist a cut-off reactive force added from the corrugated fiberboard web to the preceding and following knives, and also to give an appropriate contact force to the preceding and following knives. 
     
     
         22 . The cut off apparatus as set forth in  claim 19 , wherein said to-be-given torque pattern generated by said to-be-given torque pattern generator is a pattern having a rectangular shape, a trapezoidal shape, or a polygonal shape. 
     
     
         23 . The cut off apparatus as set forth in  claim 19 , wherein said to-be-given torque pattern generator changes the pattern of the to-be-given torque depending on the feeding speed. 
     
     
         24 . The cut off apparatus as set forth in  claim 19 , wherein said to-be-given torque pattern generator generates an identical to-be-given torque pattern for the preceding knife driving motor and the following knife driving motor. 
     
     
         25 . The cut off apparatus as set forth in  claim 19 , further comprising
 a production management device including an input unit for inputting thereto a basis weight of the corrugated fiberboard web and the sheet length to be cut off,   wherein said production management system is connected to said cut off control device for (i) outputting the basis weight of the corrugated fiberboard web to said cutting torque computing unit, (ii) computing the rotation speeds of the preceding and following knife cylinders based on the basis weight of the corrugated fiberboard web and the sheet length to be cut off, and (iii) outputting the resultantly obtained rotation speeds to said speed pattern generator.   
     
     
         26 . The cut off apparatus as set forth in  claim 19 , wherein at least either one of said preceding gear and said following gear has one or more teeth shaped so that said preceding gear and said following gear do not come into contact with each other, said one or more teeth being provided at a portion of said gear relating to a cut off operation performed by said preceding and following knives in cooperation with each other. 
     
     
         27 . The cut off apparatus as set forth in  claim 19 , wherein a part of at least either one of said preceding gear and said following gear has no teeth so that said preceding gear and said following gear do not come into contact with each other, said part with no teeth being provided at a portion of said gear relating to a cut off operation performed by said preceding and following knives in cooperation with each other. 
     
     
         28 . The cut off apparatus as set forth in  claim 19 , wherein at least either one of said preceding gear and said following gear has one or more teeth shaped so that said preceding gear and said following gear do not come into contact with each other after passing a specified distance from initiation of a cut off operation, said one or more teeth being provided at a portion of said gear relating to the cut off operation performed by said preceding and following knives in cooperation with each other. 
     
     
         29 . The cut off apparatus as set forth in  claim 19 , wherein a part of at least either one of said preceding gear and said following gear has no teeth so that said preceding gear and said following gear do not come into contact with each other after passing a specified distance from initiation of a cut off operation, said part without teeth being provided at a portion of said gear relating to the cut off operation performed by said preceding and following knives in cooperation with each other. 
     
     
         30 . The cut off apparatus as set forth in  claim 19 , wherein the preceding and following knife cylinders are cylindrical members made of carbon fiber reinforced plastic.