U.S. patent application number 10/572856 was filed with the patent office on 2006-12-28 for method and device for cutting off band-like paper member and controller of the device.
This patent application is currently assigned to Mitsubishi Heavy Industrial, Ltd.. Invention is credited to Hiroshi Ishibuchi, Satoshi Matsuda, Katsuaki Takasaki, Kuniaki Wakusawa.
Application Number | 20060288827 10/572856 |
Document ID | / |
Family ID | 37565715 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060288827 |
Kind Code |
A1 |
Ishibuchi; Hiroshi ; et
al. |
December 28, 2006 |
Method and device for cutting off band-like paper member and
controller of the device
Abstract
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.
The cut off method for a cut off apparatus including: a preceding
knife cylinder 2 on whose peripheral surface a preceding helical
knife 4 is provided; a following knife cylinder 3 on whose
peripheral surface a following helical knife 5, which cuts off
band-like paper D in cooperation with the preceding knife 4, is
provided; a preceding knife driving motor 12 which rotationally
drives the preceding knife cylinder 2; a following knife driving
motor 13 which rotationally drives the following knife cylinder 3;
and a cut off control device 20 which individually controls the
preceding knife driving motor 12 and the following knife driving
motor 13, is characterized in that the method comprises: giving,
when the band-like paper D is cut, the preceding knife 4 and the
following knife 5 a specified amount of torque in the direction in
which the preceding knife 4 and the following knife 5 are pressed
against each other, by means of the preceding knife driving motor
12 and the following knife driving motor 13.
Inventors: |
Ishibuchi; Hiroshi;
(Hiroshima-ken, JP) ; Matsuda; Satoshi; (Aichi,
JP) ; Wakusawa; Kuniaki; (Hiroshima-ken, JP) ;
Takasaki; Katsuaki; (Hiroshima-ken, JP) |
Correspondence
Address: |
KANESAKA BERNER AND PARTNERS LLP
SUITE 300, 1700 DIAGONAL RD
ALEXANDRIA
VA
22314-2848
US
|
Assignee: |
Mitsubishi Heavy Industrial,
Ltd.
Tokyo
JP
1088215
|
Family ID: |
37565715 |
Appl. No.: |
10/572856 |
Filed: |
April 28, 2005 |
PCT Filed: |
April 28, 2005 |
PCT NO: |
PCT/JP05/08184 |
371 Date: |
March 22, 2006 |
Current U.S.
Class: |
83/13 |
Current CPC
Class: |
Y10T 83/4827 20150401;
Y10T 83/04 20150401; Y10T 83/162 20150401; Y10T 83/4682 20150401;
Y10T 83/4836 20150401; Y10T 83/141 20150401; Y10T 83/159 20150401;
B26D 5/00 20130101; B26D 1/626 20130101 |
Class at
Publication: |
083/013 |
International
Class: |
B26D 1/00 20060101
B26D001/00 |
Claims
1. A cut off method for a cut off apparatus including: a preceding
knife cylinder on whose peripheral surface a preceding helical
knife is provided; a following knife cylinder on whose peripheral
surface a following helical knife, which cuts off band-like paper
in cooperation with the preceding knife, is provided; preceding
knife driving motor which rotationally drives the preceding knife
cylinder; a following knife driving motor which rotationally drives
the following knife cylinder; and a cut off control device which
individually controls the preceding knife driving motor and the
following knife driving motor, wherein said method comprises:
giving, when the band-like paper is cut, the preceding knife and
the following knife 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.
2. A cut off method as set forth in claim 1, wherein the value of
the torque given by means of the preceding knife driving motor is
the same as the value of the torque given by means of the following
knife driving motor.
3. A cut off control device for band-like paper, which device
controls a preceding knife driving motor for rotationally driving a
preceding knife cylinder on whose peripheral surface a preceding
helical knife is provided and also a following knife driving motor
for rotationally driving a following knife cylinder on whose
peripheral surface a following helical knife is provided, said
control device comprising: a speed pattern generator, to which a
paper feeding speed of the band-like paper and the sheet length to
be cut off is input, for generating rotational speed patterns of
the preceding knife driving motor and the following knife driving
motor based on the input paper feeding speed and the input sheet
length to be cut off and for outputting a speed instruction value;
a comparator which compares 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 which computes 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 which computes cutting
torque of the preceding knife driving motor and the following knife
driving motor; a to-be-given torque pattern generator which
distributes the cutting torque sent from said cutting torque
computing unit, and generates a to-be-given torque pattern based on
the paper feeding speed of the band-like paper and the sheet length
to be cut off, and outputs a to-be-given torque instruction value;
an instruction torque subtractor unit which subtracts 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 which controls the preceding knife
driving motor based on a computation result obtained by said
instruction torque subtractor; an instruction torque adder which
adds 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 which controls the
following knife driving motor based on a computation result
obtained by said instruction torque adder.
4. A cut off control device as set forth in claim 3, wherein said
cutting torque computed by said cutting torque computing unit has a
cutting torque value necessary for cutting off the band-like paper,
said cutting torque value being based on the basis weight and the
paper feeding speed input.
5. A cut off control device as set forth in claim 3, wherein said
cutting torque computed by said cutting torque computing unit is
large enough to resist a cut-off reactive force added from the
band-like paper to the preceding and following knives, and also to
give an appropriate contact force to the preceding and following
knives.
6. A cut off control device as set forth in claim 3, 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.
7. A cut off control device as set forth in claim 3, wherein said
to-be-given torque pattern generator changes the pattern of the
to-be-given torque depending on the paper feeding speed.
8. A cut off control device as set forth in claim 3, 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.
9. A cut off control device as set forth in claim 3, said cut off
control device being connected to a production management device
including an input unit for inputting thereto the basis weight of
the band-like paper and the sheet length to be cut off, which
production management system (i) outputs the basis weight of the
band-like paper to said cutting torque computing unit, and (ii)
computes the rotation speeds of the preceding and following knife
cylinders based on the basis weight of the band-like paper and the
sheet length to be cut off, and (iii) outputs the resultantly
obtained rotation speed to said speed pattern generator.
10. A cut off apparatus for cutting off band-like paper,
comprising: a preceding knife cylinder on whose peripheral surface
a preceding helical knife is provided; a following knife cylinder
on whose peripheral surface a following helical knife, which cuts
off band-like paper in cooperation with the preceding knife, is
provided; a preceding gear attached at one of the opposite ends of
the rotation axis of the preceding knife cylinder; a following gear
attached at one of the opposite ends of the rotation axis 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 which rotationally drives said
preceding drive gear; a following knife driving motor which
rotationally drives 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 which
individually controls said preceding knife driving motor and said
following knife driving motor.
11. A cut off apparatus as set forth in claim 10, 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.
12. A cut off apparatus as set forth in claim 10, 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.
13. A cut off apparatus as set forth in claim 10, 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.
14. A cut off apparatus as set forth in claim 10, 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.
15. A cut off apparatus as set forth in claim 10, wherein the
preceding and following knife cylinders are cylindrical members
made of carbon fiber reinforced plastic.
16. A cut off apparatus as set forth in claim 10, comprising the
cut off control apparatus as set forth in any one of claim 3
through claim 9.
17. A cut off apparatus for cutting off band-like paper,
comprising: a preceding knife cylinder on whose peripheral surface
a preceding helical knife is provided; a following knife cylinder
on whose peripheral surface a following helical knife, which cuts
off band-like paper in cooperation with the preceding knife, is
provided; a preceding gear attached at one of the opposite ends of
the rotation axis of the preceding knife cylinder; a following gear
attached at one of the opposite ends of the rotation axis 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 which rotationally drives said
preceding drive gear; a following knife driving motor which
rotationally drives said following drive gear; and a cut off
control device which individually controls said preceding knife
driving motor and said following knife driving motor, 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.
18. A cut off apparatus for cutting off band-like paper,
comprising: a preceding knife cylinder on whose peripheral surface
a preceding helical knife is provided; a following knife cylinder
on whose peripheral surface a following helical knife, which cuts
off band-like paper in cooperation with the preceding knife, is
provided; a preceding gear attached at one of the opposite ends of
the rotation axis of the preceding knife cylinder; a following gear
attached at one of the opposite ends of the rotation axis 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 which rotationally drives said
preceding drive gear; a following knife driving motor which
rotationally drives said following drive gear; and a cut off
control device which individually controls said preceding knife
driving motor and said following knife driving motor, 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.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a cut off method and
apparatus for band-like paper, such as a corrugated fiberboard web,
and a control apparatus for the same in a corrugating machine which
manufactures corrugated fiberboard sheets, etc.
BACKGROUND OF THE INVENTION
[0002] In a previous cut off apparatus in a corrugating machine,
various attempts have been made to reduce the rigidity of knife
cylinders and to realize a specified pressing force between knives.
In FIG. 8, for example, the cut off apparatus includes: an upper
knife cylinder 53 to which an upper knife 55 and split gears 8a and
8b are attached; a lower knife cylinder 54 to which a lower knife
56, which cuts a corrugated fiberboard web in cooperation with the
upper knife 55, and a lower gear 9 which has a meshing engagement
with the split gears 8a and 8b re-attached; a main drive motor 51
and an auxiliary drive motor 50 which rotationally drive the knife
cylinders 53 and 54; and a controller 52 which controls the drive
motors 51 and 50. Clearance is formed between the teeth of the
split gears 8a and 8b and the teeth of the lower gear 9, which
teeth have a meshing engagement with one another when the upper and
lower knives 55 and 56 come into contact with each other. The
controller 52 controls at least either one of the drive motors 51
and 50 so that a pressing force is applied between the knives 55
and 56 when these knives come into contact with each other (for
example, the following patent document 1).
[0003] [Patent document 1] Japanese Patent Application Laid-open
No. 2002-284430
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0004] However, the controller 52 in the above patent document 1
only performs torque control in such a manner that a pressing force
is generated so that the upper knife 55 is pressed against the
lower knife 56. Thus, it is difficult to accurately cut off
band-like paper such as a corrugated fiberboard sheet. Further, the
rated power capacities (size) of the upper motor and the lower
motor are different, so that the number of types of components
including a control device is increased.
[0005] With the foregoing problems in view, it is an object of the
present invention to provide a cut off method and apparatus for
band-like paper and a control apparatus for the same, in which
torque necessary for cutting off the band-like paper is properly
distributed to the upper (preceding) and the lower (following)
motor, so that the band-like paper such as a corrugated fiberboard
sheet is accurately cut off. Further it is another object of the
present invention to reduce the number of types of components by
equalizing the rated power capacities of the upper motor and the
lower motor.
MEANS TO SOLVE THE PROBLEMS
[0006] In order to accomplish the above object, according to the
present invention, a cut off method for a cut off apparatus as set
forth in claim 1 is characterized in that which apparatus includes:
a preceding knife cylinder on whose peripheral surface a preceding
helical knife is provided; a following knife cylinder on whose
peripheral surface a following helical knife, which cuts off
band-like paper in cooperation with the preceding knife, is
provided; a preceding knife driving motor which rotationally drives
the preceding knife cylinder; a following knife driving motor which
rotationally drives the following knife cylinder; and a cut off
control device which individually controls the preceding knife
driving motor and the following knife driving motor, wherein the
method comprises: giving, when the band-like paper is cut, the
preceding knife and the following knife 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.
[0007] A cut off method as set forth in claim 2 is characterized in
that the value of the torque given by means of the preceding knife
driving motor is the same as the value of the torque given by means
of the following knife driving motor.
[0008] A cut off control device for band-like paper as set forth in
claim 3, which device controls a preceding knife driving motor for
rotationally driving a preceding knife cylinder on whose peripheral
surface a preceding helical knife is provided and also a following
knife driving motor for rotationally driving a following knife
cylinder on whose peripheral surface a following helical knife is
provided, is characterized in that the device comprises: a speed
pattern generator, to which a paper feeding speed of the band-like
paper and the sheet length to be cut off is input, for generating
rotational speed patterns of the preceding knife driving motor and
the following knife driving motor based on the input paper feeding
speed and the input sheet length to be cut off and for outputting a
speed instruction value; a comparator which compares the speed
instruction value from the speed pattern generator with a detected
speed of the preceding knife driving motor or the following knife
driving motor; an instruction torque computing unit which computes
rotational torque instruction values for the preceding knife
driving motor and the following knife driving motor based on a
signal from the comparator; a cutting torque computing unit which
computes cutting torque of the preceding knife driving motor and
the following knife driving motor; a to-be-given torque pattern
generator which distributes the cutting torque sent from the
cutting torque computing unit, and generates a to-be-given torque
pattern based on the paper feeding speed of the band-like paper and
the sheet length to be cut off, and outputs a to-be-given torque
instruction value; an instruction torque subtractor unit which
subtracts the to-be-given torque instruction value, output from the
to-be-given torque pattern generator, from the rotational torque
instruction value computed by the instruction torque computing
unit; a preceding power amplifier which controls the preceding
knife driving motor based on a computation result obtained by the
instruction torque subtractor; an instruction torque adder which
adds the rotational torque instruction value, computed by the
instruction torque computing unit, to the to-be-given torque
instruction value computed by the to-be-given torque pattern
generator; and a following power amplifier which controls the
following knife driving motor based on a computation result
obtained by the instruction torque adder.
[0009] A cut off control device as set forth in claim 4 is
characterized in that, in the device as set forth in claim 3, the
cutting torque computed by the cutting torque computing unit has a
cutting torque value necessary for cutting off the band-like paper,
the cutting torque value being based on the basis weight and the
paper feeding speed input.
[0010] A cut off control device as set forth in claim 5 is
characterized in that, in the device as set forth in claim 3 or
claim 4, the cutting torque computed by the cutting torque
computing unit is large enough to resist a cut-off reactive force
added from the band-like paper to the preceding and following
knives, and also to give an appropriate contact force to the
preceding and following knives.
[0011] A cut off control device as set forth in claim 6 is
characterized in that, in the device as set forth in any one of
claim 3 through claim 5, the to-be-given torque pattern generated
by the to-be-given torque pattern generator is a pattern having a
rectangular shape, a trapezoidal shape, or a polygonal shape.
[0012] A cut off control device as set forth in claim 7 is
characterized in that, in the device as set forth in any one of
claim 3 through claim 6, the to-be-given torque pattern generator
changes the pattern of the to-be-given torque depending on the
paper feeding speed.
[0013] A cut off control device as set forth in claim 8 is
characterized in that, in the device as set forth in any one of
claim 3 through claim 7, the 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.
[0014] A cut off control device as set forth in claim 9 is
characterized in that, in the device as set forth in any one of
claim 3 through claim 8, the cut off control device is connected to
a production management device including an input unit for
inputting thereto the basis weight of the band-like paper and the
sheet length to be cut off, which production management system (i)
outputs the basis weight of the band-like paper to the cutting
torque computing unit, and (ii) computes the rotation speeds of the
preceding and following knife cylinders based on the basis weight
of the band-like paper and the sheet length to be cut off, and
(iii) outputs the resultantly obtained rotation speed to the speed
pattern generator.
[0015] A cut off apparatus for cutting off band-like paper is
characterized in that the apparatus comprises: a preceding knife
cylinder on whose peripheral surface a preceding helical knife is
provided; a following knife cylinder on whose peripheral surface a
following helical knife, which cuts off band-like paper in
cooperation with the preceding knife, is provided; a preceding gear
attached at one of the opposite ends of the rotation axis of the
preceding knife cylinder; a following gear attached at one of the
opposite ends of the rotation axis of the following knife cylinder;
a preceding drive gear which has a meshing engagement with the
preceding gear; a following drive gear which has a meshing
engagement with the following gear; a preceding knife driving motor
which rotationally drives the preceding drive gear; a following
knife driving motor which rotationally drives the following drive
gear, the following knife driving motor having the same rated
capacity as that of the preceding knife driving motor; and a cut
off control device which individually controls the preceding knife
driving motor and the following drive gear.
[0016] A cut off apparatus as set forth in claim 11 is
characterized in that, in the apparatus as set forth in claim 10,
at least either one of the preceding gear and the following gear
has one or more teeth shaped so that the preceding gear and the
following gear do not come into contact with each other, the one or
more teeth being provided at a portion of the gear relating to a
cut off operation performed by the preceding and following knives
in cooperation with each other.
[0017] A cut off apparatus as set forth in claim 12 is
characterized in that, in the apparatus as set forth in claim 10, a
part of at least either one of the preceding gear and the following
gear has no teeth so that the preceding gear and the following gear
do not come into contact with each other, the part with no teeth
being provided at a portion of the gear relating to a cut off
operation performed by the preceding and following knives in
cooperation with each other.
[0018] A cut off apparatus as set forth in claim 13 is
characterized in that, in the apparatus as set forth in claim 10,
wherein at least either one of the preceding gear and the following
gear has one or more teeth shaped so that the preceding gear and
the following gear do not come into contact with each other after
passing a specified distance from initiation of a cut off
operation, the one or more teeth being provided at a portion of the
gear relating to the cut off operation performed by the preceding
and following knives in cooperation with each other.
[0019] A cut off apparatus as set forth in claim 14 is
characterized in that, in the apparatus as set forth in claim 10, a
part of at least either one of the preceding gear and the following
gear has no teeth so that the preceding gear and the following gear
do not come into contact with each other after passing a specified
distance from initiation of a cut off operation, the part without
teeth being provided at a portion of the gear relating to the cut
off operation performed by the preceding and following knives in
cooperation with each other.
[0020] A cut off apparatus as set forth in claim 15 is
characterized in that, in the apparatus as set forth in any one of
claim 10 through claim 14, the preceding and following knife
cylinders are cylindrical members made of carbon fiber reinforced
plastic.
[0021] A cut off apparatus as set forth in claim 16 is
characterized in that the apparatus as set forth in any one of
claim 10 through claim 15 comprises the cut off control apparatus
as set forth in any one of claim 3 through claim 9.
[0022] A cut off apparatus for cutting off band-like paper as set
froth in claim 17 is characterized in that the apparatus comprises:
a preceding knife cylinder on whose peripheral surface a preceding
helical knife is provided; a following knife cylinder on whose
peripheral surface a following helical knife, which cuts off
band-like paper in cooperation with the preceding knife, is
provided; a preceding gear attached at one of the opposite ends of
the rotation axis of the preceding knife cylinder; a following gear
attached at one of the opposite ends of the rotation axis of the
following knife cylinder; a preceding drive gear which has a
meshing engagement with the preceding gear; a following drive gear
which has a meshing engagement with the following gear; a preceding
knife driving motor which rotationally drives the preceding drive
gear; a following knife driving motor which rotationally drives the
following drive gear; and a cut off control device which
individually controls the preceding knife driving motor and the
following knife driving motor, wherein at least either one of the
preceding gear and the following gear has one or more teeth shaped
so that the preceding gear and the following gear do not come into
contact with each other after passing a specified distance from
initiation of a cut off operation, the one or more teeth being
provided at a portion of the gear relating to the cut off operation
performed by the preceding and following knives in cooperation with
each other.
[0023] A cut off apparatus for cutting off band-like paper as set
forth in claim 18 is characterized in that the apparatus comprises:
a preceding knife cylinder on whose peripheral surface a preceding
helical knife is provided; a following knife cylinder on whose
peripheral surface a following helical knife, which cuts off
band-like paper in cooperation with the preceding knife, is
provided; a preceding gear attached at one of the opposite ends of
the rotation axis of the preceding knife cylinder; a following gear
attached at one of the opposite ends of the rotation axis of the
following knife cylinder; a preceding drive gear which has a
meshing engagement with the preceding gear; a following drive gear
which has a meshing engagement with the following gear; a preceding
knife driving motor which rotationally drives the preceding drive
gear; a following knife driving motor which rotationally drives the
following drive gear; and a cut off control device-which
individually controls the preceding knife driving motor and the
following knife driving motor, wherein a part of at least either
one of the preceding gear and the following gear has no teeth so
that the preceding gear and the following gear do not come into
contact with each other after passing a specified distance from
initiation of a cut off operation, the part without teeth being
provided at a portion of the gear relating to the cut off operation
performed by the preceding and following knives in cooperation with
each other.
EFFECTS OF THE PRESENT INVENTION
[0024] The invention described in each claim exerts the following
effects.
[0025] According to the invention as set forth in claim 1, the
preceding knife driving motor and the following knife driving motor
are provided with a specified amount of torque in the direction of
contact, so that band-like paper is accurately cut off. By
individually applying torque, the edges of the knives are made to
come into contact with each other, and the cut off operation of the
band-like paper is performed by the edge of one of the knives and
the edge of the other knife coming into contact with each other. As
a result, in comparison with a previous case in which knife
cylinders with high rigidity are used and preload is applied to the
edges of the knives, the cutting load is reduced in the present
invention. Further, the rigidity and GD.sup.2 of the knife
cylinders are reduced, so that the necessary capacity for each
knife driving motor is considerably reduced. Furthermore, the
band-like paper is cut under a condition where the edge of one of
the knives and the edge of the other one of the knives come into
contact with each other, so that edge adjustment can be
approximately (easily) performed.
[0026] According to the present invention as set forth in claim 2,
the following advantageous effects are guaranteed in addition to
the effects realized by the invention as set forth in claim 1.
Torque applied by the preceding knife driving motor and the
following knife driving motor is cancelled, while band-like paper
is being cut. Thus, paper feeding of the band-like paper is not
influenced, so that it is possible to cut off the band-like paper
with the utmost of accuracy.
[0027] According to the invention as set forth in claim 3, the
to-be-given torque pattern generator distributes cutting torque
necessary for cutting off the band-like paper, thereby controlling
the preceding knife driving motor or the following knife driving
motor. Thus, paper feeding of the band-like paper is not
influenced, so that it is possible to cut off the band-like paper
accurately.
[0028] According to the invention as set forth in claim 4, the
following advantageous effects are guaranteed in addition to the
effects realized by the invention as set forth in claim 3. The
cutting torque can be changed in accordance with the basis weight
and the paper feeding speed of the band-like paper.
[0029] According to the invention as set forth in claim 5, the
following advantageous effects are guaranteed in addition to the
effects realized by the invention as set forth in claim 3 or claim
4, since a contact force is generated between the preceding knife
and the following knife while the band-like paper is being cut, it
is possible to suppress an edge gap between the preceding knife and
the following knife.
[0030] According to the invention as set forth in claim 6, the
following advantageous effects are guaranteed in addition to the
effects realized by any one of claim 3 through claim 5. It is
possible to select an appropriate to-be-given torque pattern in
accordance with the paper feeding speed.
[0031] According to the invention as set forth in claim 7, the
following advantageous effects are guaranteed in addition to the
effects realized by any one of claim 3 through claim 6. It is
possible to realize the optimum cutting of the band-like paper in
accordance with the paper feeding speed, by using an even torque
pattern when the rotation speed of the preceding knife driving
motor and the following knife driving motor is low or intermediate,
and by using a rectangular-shaped torque pattern when the rotation
speed of the two knife driving motors is high.
[0032] According to the invention as set forth in claim 8, the
following advantageous effects are guaranteed in addition to the
effects realized by any one of claim 3 through claim 7. Since the
same torque pattern is given to the preceding knife driving motor
and the following knife driving motor, the paper feeding of the
band-like paper is not influenced while the band-like paper is
being cut, so that the band-like paper can be cut off
accurately.
[0033] According to the invention as set forth in claim 9, the
following advantageous effects are guaranteed in addition to the
effects realized by any one of claim 3 through claim 8. It is
possible for the production management device to change the basis
weight of the band-like paper to be cut off and the sheet length to
be cut off. Further, in comparison with the previous art, in which
the cutting load corresponding to the maximum basis weight is
always applied, it is possible, in the present invention, to change
the cutting load in accordance with the basis weight of the
band-like paper, so that the wearing away of each knife is reduced,
thereby lengthening the life of each knife.
[0034] According to the invention as set forth in claim 10, since
the rated capacities of the preceding knife driving motor and the
following knife driving motor are the same, it is possible to
employ the driving motors with the same capacity and also the power
amplifiers with the same capacity.
[0035] According to the present invention as set forth in claim 11
and claim 12, the following advantageous effects are guaranteed in
addition to the effects realized by the invention as set forth in
claim 10. When the preceding knife and the following knife are not
in contact with each other, the preceding gear and the following
gear have a meshing engagement with each other while the preceding
knife driving motor and the following knife driving motor are
operated in synchronism with each other, or are operated in
acceleration or deceleration, so that synchronism is reliably
guaranteed. In addition, when the two knives are in contact with
each other while cutting the band-like paper, the preceding gear
and the following gear do not have a meshing engagement, so that it
is possible to control the preceding knife driving motor and the
following knife driving motor separately. This realizes an
appropriate cutting force.
[0036] According to the present invention as set forth in claim 13
and claim 14, correct knife order can be maintained, and it can be
prevented that the following knife precedes the preceding knife
(inverse edge) at the initiation of the cutting operation between
the preceding knife and the following knife. This will prevent
damage to both knives, so that a high-quality and accurate cutting
operation is possible.
[0037] According to the invention as set forth in claim 15, the
following advantageous effects are guaranteed in addition to the
effects realized by the invention as set forth in any one of claim
10 through claim 14. It is possible to reduce the rotational
inertial force of the preceding knife cylinder and the following
knife cylinder, so that control without delay is available.
[0038] According to the invention as set forth in claim 16, the
effect as set forth any of claim 3 through claim 9 in addition to
any one of claim 10 through claim 15 is realized.
[0039] According to the invention as set forth in claim 16 and
claim 17, it can be prevented that the following knife precedes the
preceding knife (inverse edge) at the initiation of the cutting
operation between the preceding knife and the following knife. This
will prevent damage to both knives, so that a high-quality and
accurate cutting operation is possible.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] [FIG. 1] FIG. 1 is a schematic front view of a cut off
apparatus according to one preferred embodiment of the present
invention;
[0041] [FIG. 2] FIG. 2 is a section taken along the arrow line A-A
of FIG. 1;
[0042] [FIG. 3] FIG. 3 is a schematic side view showing the state
of the upper and the lower gear at the time the upper and lower
knives of the cut off apparatus of the present embodiment start a
cut off operation;
[0043] [FIG. 4] FIG. 4 is a schematic side view showing the state
of the upper and the lower gear at the time the upper and lower
knives of the cut off apparatus of the present embodiment complete
the cut off operation;
[0044] [FIG. 5] FIG. 5 is a control block diagram showing a cut off
control device according to the present embodiment;
[0045] [FIG. 6] FIG. 6(A) through FIG. 6(E) are diagrams each
showing a control pattern for each knife driving motor according to
the present embodiment;
[0046] [FIG. 7] FIG. 7 is a diagram showing another example of a
torque pattern given by each knife driving motor according to the
present invention; and
[0047] [FIG. 8] FIG. 8 is a schematic front view showing a previous
cut off apparatus.
REFERENCES
[0048] 1 . . . frame
[0049] 2 . . . upper (preceding) knife cylinder
[0050] 3 . . . lower (following) knife cylinder
[0051] 4 . . . upper (preceding) knife
[0052] 5 . . . lower (following) knife
[0053] 6,7 . . . rotation axis
[0054] 8 . . . upper (preceding) gear
[0055] 8a,8b . . . split gear
[0056] 9 . . . lower (following) gear
[0057] 10 . . . upper (preceding) drive gear
[0058] 11 . . . lower (following) drive gear
[0059] 12 . . . upper (preceding) knife driving motor
[0060] 13 . . . lower (following) knife driving motor
[0061] 14 . . . encoder
[0062] 20 . . . cut off control device
[0063] 21 . . . instruction value computing unit
[0064] 22 . . . position computing unit
[0065] 23 . . . cutting torque computing unit
[0066] 24 . . . speed pattern generator
[0067] 25 . . . to-be-given torque pattern generator
[0068] 30 . . . upper (preceding) knife speed control unit
[0069] 31 . . . comparator
[0070] 32 . . . instruction torque computing unit
[0071] 33 . . . instruction torque subtractor
[0072] 34 . . . upper (preceding) power amplifier
[0073] 35 . . . lower (following) knife speed control unit
[0074] 36 . . . instruction torque adder
[0075] 37 . . . lower (following) power amplifier
[0076] 40 . . . production management device
[0077] 41 . . . paper feed control device
[0078] D . . . band-like paper
[0079] C . . . start point of a cut off operation
[0080] O . . . end point of a cut off operation
[0081] S . . . leading ends of the upper and lower knives (start
point of contact)
[0082] E . . . terminal ends of the upper and lower knives (end
point of contact)
[0083] t1 . . . time when contact starts
[0084] t2 . . . time at start of speed reduction
[0085] t3 . . . time when waiting is started
[0086] t4 . . . time when 1 cycle is completed
[0087] tc . . . time at start of cut-off operation
[0088] to . . . time at end of cut-off operation
[0089] Vs . . . paper feeding speed
[0090] L . . . sheet length to be cut off
[0091] W . . . basis weight
[0092] B . . . width of the band-like paper
[0093] Pt . . . current position
[0094] Tt . . . rotational torque instruction value
[0095] Vt . . . speed instruction value
[0096] Txa,Txb . . . cutting torque
[0097] Txat,Txbt . . . to-be-given torque instruction value
[0098] St . . . detected speed
[0099] Q . . . specified length
BEST MODE FOR CARRYING OUT THE INVENTION
[0100] A description will be made hereinbelow of a best mode for
carrying out the invention. FIG. 1 is a schematic front view of a
cut off apparatus according to one preferred embodiment of the
present invention; FIG. 2 is a section taken along the arrow line
A-A of FIG. 1; FIG. 3 is a schematic side view showing the state of
the upper and the lower gear at the time the upper and lower knives
of the cut off apparatus of the present embodiment start a cut off
operation; FIG. 4 is a schematic side view showing the state of the
upper and the lower gear at the time the upper and lower knives of
the cut off apparatus of the present embodiment complete the cut
off operation; FIG. 5 is a control block diagram showing a cut off
control device according to the present embodiment; FIG. 6(A)
through FIG. 6(E) are diagrams each showing a control pattern for
each knife driving motor according to the present embodiment; FIG.
7 is a diagram showing another example of a pressure torque
(to-be-given torque) pattern given by each knife driving motor
according to the present invention.
[0101] First of all, referring to FIG. 1 and FIG. 2, a description
will be made of a construction of a cut off apparatus for cutting
off band-like paper D such as a corrugated fiberboard web in a
corrugating machine. As shown in FIG. 1 and FIG. 2, parallel
rotational axes 6 and 7 are provided, passing through the frames 1
and 1 on both sides. Here, the rotational axes 6 and 7 are made of
metal and have high rigidity.
[0102] On the peripheral surfaces of the rotational axes 6 and 7,
an upper (preceding) knife cylinder 2 and a lower (following) knife
cylinder 3, which have cylindrical shapes, are attached via radial
posts. The upper knife cylinder 2 and the lower knife cylinder 3
are made of a material, for example, CFRP (Carbon Fiber Reinforced
Plastic: called carbon fiber for short), with high rigidity but
with small GD.sup.2 (rotational inertial force). Such shapes and
materials of the rotational axes 6 and 7 and the upper and lower
knife cylinders 2 and 3 reduce GD.sup.2, thereby making it possible
to realize rotation control superior in responsibility and
rapidity.
[0103] In the previous art, the upper and lower knife cylinders 2
and 3 are made of a material with large GD.sup.2, and preload
generated by the rotational inertial force and by a bend of one of
the upper and lower knives provides a pressing force necessary for
cutting off the band-like paper D. As will be described below,
however, torque given by the upper (preceding) knife driving motor
12 and the lower (following) knife driving motor 13 provides a
cutting force in the present embodiment, so that the upper knife
cylinder 2 and the lower knife cylinder 3 can be made of a material
with small GD.sup.2 (rotational inertial force).
[0104] On the peripheral surface of the upper knife cylinder 2, an
upper (preceding) knife 4 with a vertical edge, which faces
outwards in the radial direction, is attached in the helical form.
On the peripheral surface of the lower knife cylinder 3, a lower
(following) knife 5 with a horizontal edge., which extends in the
peripheral direction, is attached in helical form. When cutting
band-like paper D, such as a corrugated fiberboard web, the upper
knife 4 and the lower knife 5 operate in cooperation. More
specifically, the band-like paper is sandwiched between the upper
knife 4 and the lower knife 5, which are pressed against each
other. The point at which the edges of the two knives come into
contact with each other moves from one of the ends of the band-like
paper to the other end thereof, whereby the band-like paper is cut
off. Here, in FIG. 1 and FIG. 2, reference character S designates
the leading end (the cutting start point) of the upper and lower
knives, and reference character E designates the terminal end (the
cutting end point) of the upper and lower knives.
[0105] The previous art employs a knife cylinder with high rigidity
to apply preload to the edge of the knife for a cutting operation.
As described so far, however, according to the present embodiment,
the upper knife 4 and the lower knife 5 engage in the direction in
which the edge of the upper knife 4 and the edge of the lower knife
5 come into contact with each other, whereby the band-like paper D
is cut, so that the preload is considerably reduced and adjustment
of the edges of the knives can be roughly (easily) performed.
Further, as will be described below, as torque is given to each of
the cylinders, the rigidity of each knife cylinder 2 and 3 and
their GD.sup.2 are reduced. In addition, in contrast to the
previous art in which cutting load corresponding to the maximum
basis weight is always applied, the present art is capable of
changing the cutting load (torque) depending upon the basis weight
of the band-like paper D, so that the life-time of each knife 4 and
5 is increased.
[0106] Here, FIG. 2 exaggerates the upper knife 4 and the lower
knife 5 for purposes of illustration, and in an actual case, the
diameters of the upper knife cylinder 2 and the lower knife
cylinder 3 are significantly large. A helical recess is provided on
a part of each knife cylinder 2 and 3, and the upper knife 4 and
the lower knife 5 are fitted into the recesses.
[0107] Further, the upper knife 4, the lower knife 5, the upper
knife cylinder 2, the lower knife cylinder 3, the rotational axes 6
and 7 can be constructed in the following way. That is, each of the
upper knife cylinder 2 and the lower knife cylinder 3 is a hollow
cylindrical member made of carbon fiber reinforced plastic with
disk-like lids at the opposite ends thereof (or formed in one
piece). At the centers of the lids, rotational axes 6 and 7 made of
metal are bonded or fixed with bolts and nuts, etc. On the
peripheral surface of the upper knife cylinder 2 and the lower
knife cylinder 3, which have cylindrical shapes made of carbon
fiber reinforced plastic, holders made of aluminum or iron or
carbon fiber reinforced plastic are attached. On each of the
holders, the upper knife 4 and the lower knife 5 are mounted
respectively in helical form with bolts and nuts, etc. Further, at
the opposite ends of the upper knife cylinder 2 and the lower knife
cylinder 3 with a hollow cylindrical shape made of carbon fiber
reinforced plastic, rotational axes 6 and 7 with metal lids can be
fixed.
[0108] On one end the right part of FIG. 1) of the rotational axis
6, an upper (preceding) gear 8 including split gears 8a and 8b is
attached. On one end (the right part of FIG. 1) of the rotational
axis 7, the lower (following) gear 9 which has a meshing engagement
with the upper gear 8 is attached. Two split-gears 8a and 8b are
fixed to the rotational axis 6 slightly shifted from each other in
the rotational direction, so that backlash in meshing engagement
with the lower gear 9 while the upper knife 4 and the lower knife 5
are not in contact with each other is prevented. In this instance,
the upper gear 8 can be formed as a single gear and the lower gear
9 can be formed by two split gears. Further, the upper gear 8 or
the lower gear 9 is not necessarily formed by two gears, and each
of the upper gear 8 and the lower gear 9 can be prepared as a
single gear.
[0109] An upper (preceding) knife driving motor 12 is connected to
the upper gear 8 via an upper (preceding) drive gear 10, which has
a meshing engagement with the upper gear 8. A lower (following)
knife driving motor 13 is connected to the lower gear 9 via a lower
(following) drive gear 11 which has a meshing engagement with the
lower gear 9. These knife driving motors 12 and 13 are torque
motors with the same rated capacity and the same output power, and
these motors 12 and 13 are individually controlled by a cut off
control device 20. Either one (for example, the lower knife driving
motor 13) of these motors 12 and 13 is attached with an encoder 14
which detects the rotational speed of the motor.
[0110] The upper gear 8 and the lower gear 9 have the following
characteristic features. The upper gear 8 and the lower gear 9 have
a meshing engagement with each other without backlash in a range
thereof in which the upper knife 4 and the lower knife 5 do not
come into contact with each other. As shown in FIG. 3 and FIG. 4,
in a range (from the cutting start point C to the cutting end point
O) in which the upper knife 4 and the lower knife 5 come into
contact with each other, thereby carrying out a cutting operation,
one of the opposite sides of the teeth of at least one of the split
gears 8a and 8b, which side faces the teeth of the lower gear 9
when pressure (given) torque Txat and Txbt is applied, is cut as
shown with shaded areas in FIG. 3 and FIG. 4. In this manner, at
least in a range from the cutting start point C to the cutting end
point 0, the edges of the upper knife 4 and the lower knife 5 come
into contact with each other, but the teeth of the upper gear 8 and
the lower gear 9 do not come into contact with each other.
[0111] Here, the cutting start point C and the cutting end point O
depend on the width B of the band-like paper D. Accordingly, in a
range from the leading end (cutting start point) S of the upper and
lower knives to the terminal end (cutting end point) E of the upper
and lower knives, shaded areas in FIG. 3 and FIG. 4 are cut.
[0112] With this arrangement, it becomes possible for the upper
knife driving motor 12 and the lower knife driving motor 13 to
operate in synchronization with each other with reliability when
the upper knife 4 and the lower knife 5 do not come into contact
with each other. Further, when the upper knife 4 and the lower
knife 5 come into contact with each other, thereby carrying out a
cutting operation 10 (or when the upper knife 4 and lower knife 5
are in contact with each other), the upper gear 8 and the lower
gear 9 do not have a mesh engagement with each other. Thus, the
upper knife driving motor 12 and the lower knife driving motor 13
can be controlled separately, thereby providing 15 an appropriate
pressing force between the upper knife 4 and the lower knife 5, so
that an optimum cutting force is realized for the band-like paper
D.
[0113] Here, if each of the upper gear 8 and lower gear 9 20 is
provided as a single gear, one of the opposite sides of the teeth
of at least one of the upper gear 8 and the lower gear 9, which
teeth are arranged in a range from the cutting start point C to the
cutting end point O [or a range from the leading end (cutting start
point) S to 25 the terminal end (cutting end point) E of the upper
and lower knives], should be cut. Further, at least either one of
the upper gear 8 and the lower gear 9 can be formed so as not to
have any teeth in a range from the cutting start point C to the
cutting end point O. Furthermore, the width of all the teeth of
either one of the upper gear 8 and the lower gear 9 can be
reduced.
[0114] Here, if the teeth of the upper gear 8 and the lower gear 9
in a range from the leading end S of the upper and lower knives to
the terminal end E of the upper and lower knives are cut (or
removed) (that is, backlash is provided for the upper gear 8 and
the lower gear 9 in a range from the leading end S of the upper and
lower knives to the terminal end E of the upper and lower knives),
there is a possibility that the lower (following) knife 5 precedes
the upper (preceding) knife 4 (that is, "inverse edge" occurs). In
particular, when the timing with which torque control is started is
incorrect, inverse edge often occurs.
[0115] Therefore, to prevent the occurrence of the inverse edge,
the teeth of the upper gear 8 and the lower gear 9 in a range
(specified distance) corresponding to a specified length (the
lengths of the edges of the upper and lower knives in the axial
direction) Q from the leading end S of the upper and lower knives
should not be cut (or removed). That is, backlash is not provided
for the upper gear 8 and the lower gear 9 in a range corresponding
to the specified length Q from the leading end S of the upper and
lower knives. In addition, backlash is provided in a range from the
point after passing the specified length to the terminal end E of
the upper and lower knives.
[0116] As a result, the occurrence of inverse edge between the
upper and lower knives is prevented at initiation of a cutting
operation, so that damage to the upper and lower knives are
prevented and a high-quality and accurate cutting operation can be
realized.
[0117] In this instance, if the specified length Q is significantly
shorter than about 100 mm, there is a possibility that the inverse
edge prevention effect cannot be exerted. Further, if the specified
length is significantly longer than 200 mm, there is a possibility
that cutting effect which should be realized by torque control is
not exerted. Thus, the specified length Q preferably falls within a
range of about 100 mm to 200 mm from the leading end of the upper
and lower knives.
[0118] Here, FIG. 3 and FIG. 4 are schematic views, in which the
upper knife 4 and the lower knife 5 are separated from each other.
In a practical case, however, the upper knife 4 and the lower knife
5 are provided in the vicinity of the teeth of the upper gear 8 and
the lower gear 9 as shown in FIG. 2, and the edges of the upper
knife 4 and the lower knife 5 are arranged so as to come into
contact with each other.
[0119] Further, the cut off apparatus shown in FIG. 1 and FIG. 2
has the upper knife 4 with a vertical edge and the lower knife 5
with a horizontal edge. The present invention, however, should by
no means be limited to this, and the vertical and horizontal edges
can be exchanged. Further, both of the knives can have vertical
edges or horizontal edges.
[0120] Next, referring to FIG. 5, FIG. 6(A) through FIG. 6(E), and
FIG. 7, a description will be made of a cut off control device 20
which cuts off band-like paper, such as a corrugated fiberboard
web, in a corrugating machine which manufactures corrugated
fiberboard sheets or the like according to the present embodiment.
The corrugating machine which manufactures corrugated fiberboard
sheets, etc. has a production management device 40 that manages and
controls the production of the whole corrugating machine.
[0121] The production management device 40 includes: a keyboard
(input unit) for inputting therethrough the basis weight (or
material, thickness, width, etc.) of band-like paper D such as a
corrugated fiberboard sheet, the length L of a sheet to be cut off,
the paper feeding speed Vs (or the number of sheets to be cut off
per unit time); a display; a memory which records various types of
data; and a Central Processing Unit (CPU). By inputting the basis
weight W of band-like paper D such as corrugated fiberboard sheets
to be cut off and the sheet length to be cut off, it is possible to
change various setting values.
[0122] In this instance, a non-illustrated paper feeding device
which feeds band-like paper D, such as a corrugate fiberboard web,
to the cut off apparatus is provided with a paper feed control
device 41. On the basis of paper feeding speed Vs which is sent
from the production management device 40, the paper feed control
device 41 controls the paper feeding speed in which the band-like
paper D is fed.
[0123] On the other hand, the cut off apparatus is provided with a
cut off control device 20, which includes: an instruction value
computing unit 21 for generating various types of patterns; an
upper (preceding) knife speed control unit 30 for controlling drive
current applied to the upper knife driving motor 12; and a lower
(following) knife speed control unit 35 for controlling drive
current applied to the lower knife driving motor 13. The production
management device 40 sends the paper feeding speed Vs, the sheet
length L to be cut off, and the basis weight W, to the cut off
control device 20.
[0124] The instruction value computing unit 21 includes: a speed
pattern generator 24 for generating speed patterns; a to-be-given
torque pattern generator 25 for generating Torque pattern for
cutting off band-like paper D; and a cutting torque computing unit
23 for computing necessary torque for a cut off operation.
[0125] The speed pattern generator 24 receives the paper feed speed
Vs and the sheet length to be cut off for band-like paper D from
the production management device 40, and generates a speed pattern
shown in FIG. 6(A). That is, on the basis of the paper feeding
speed Vs and the sheet length to be cut off, start time t1 of
joining between the upper knife 4 and the lower knife 5, start time
tc of a cutting operation, completion time t0 of a cutting
operation, time t2 at which joining is completed and deceleration
is started, time t3 at which deceleration is completed and standby
is started, time t4 at which one cycle is completed, are computed
for one cycle. Further, the speeds in a speed-up step (t0 through
t1), a knife joining step (t1 through t2), a speed-down step (t2
through t3), a standby step (t3 through t4), are also computed.
[0126] Here, during the standby time (t3 through t4), the speed can
be zero. Further, in cases where the paper feeding speed Vs is
large and the sheet length to be cut off is long, the speed can be
greater in the standby time (t3 through t4) than in the cutting
time (time between tc and to). In this manner, the speed pattern
shown in FIG. 6(A) is generated, and the generated speed pattern is
stored in an unillustrated storage device. Further, the cutting
start time tc and the cutting completion time to are sent to the
to-be-given torque pattern generator 25.
[0127] During a cutting operation of band-like paper D, the
position computing unit 22 receives the detection speed St detected
by an encoder 14 attached to the lower knife driving motor 13. The
detection speed St is integrated, whereby the current position Pt
of the upper knife 4 and the lower knife 5 and elapsed time t
elapsed from the start time t0 of one cycle is calculated. Then,
the speed pattern generator 24 computes the speed instruction value
Vt at the elapsed time t based on the recorded speed pattern. This
calculated speed instruction value Vt is sent to the comparator
31.
[0128] Next, the cutting torque computing unit 23 receives the
paper feeding speed Vs and the basis weight of the band-like paper
D from the production management device 40, and computes cutting
torque (Txa+Txb) necessary for cutting the band-like paper D having
the basis weight W at the paper feeding speed Vs by means of the
upper knife driving motor 12 and the lower knife driving motor
13.
[0129] Here, the cutting torque (Txa+Txb) is changed with change in
the paper feeding speed Vs and in the width B of the band-like
paper. Further, the value of cutting torque (Txa+Txb) should be
large enough to resist a cut-off reactive force added from the
band-like paper D to the upper and lower knives 4 and 5, and also
to give an appropriate contact force to the upper and lower knives
4 and 5. This contact force is preferably 100 kgf to 300 kgf in the
horizontal direction.
[0130] With this arrangement, when the band-like paper D is cut, a
contact force is caused between the upper knife 4 and the lower
knife 5 so that an edge gap between the upper knife 4 and the lower
knife 5 is suppressed to a value equal to or smaller than a limit
value which can be used in a cutting operation. The computed
cutting torque (Txa+Txb) is sent to the to-be-given torque pattern
generator 25.
[0131] The to-be-given torque pattern generator 25 generates a
to-be-given torque pattern shown in FIG. 6(C) based on the cutting
torque (Txa+Txb), necessary for a cutting operation, sent from the
cutting torque computing unit 23, the cutting start time tc, and
the cutting completion time to, and stores the generated torque
pattern in an unillustrated storage device. In the to-be-given
torque pattern shown in FIG. 6(C), the cutting torque Txa necessary
for the upper knife driving motor 12 and the cutting torque Txa
necessary for the lower knife driving motor 13 have the same
rectangular shape. In this instance, the above to-be-given torque
pattern can have a trapezoidal shape with increase from t1 to tc
and decrease from t0 to t2. Further, the cutting torques Txa and
Txb can start to be given before the joining start time t1 (for
example, immediately before the upper and lower knives come into
contact with each other). Here, as already described, backlash is
not provided for the upper gear 8 and the lower gear 9 in a range
corresponding to a specified length Q from the leading end S of the
upper and lower knives, and backlash is provided in a range after
passing the specified length Q to the terminal end E of the upper
and lower knives. Further, the cutting torque Txa and Txb are
applied before the joining start time t1, whereby inverse edges can
be reliably prevented at the initiation of a cutting operation.
[0132] It is preferable that the cutting torque Txa and the cutting
torque Txb have the same absolute value (that is, torque pattern
given to the upper knife driving motor 12 and the lower knife
driving motor 13 have an identical shape and are of opposite
signs). This makes it possible to accurately cut the band-like
paper D, with no effect on the paper feeding of the band-like paper
D at the time the paper D is cut.
[0133] However, the absolute values of torque need not always be
equal, and one of the cutting torques Txa and Txb of the upper
knife driving motor 12 and the lower knife driving motor 13 can be
larger within a range allowed by the rate capacity of the upper
knife driving motor 12 and the lower knife driving motor 13. Here,
the meaning of the rate capacity of each torque motor of the
present embodiment includes not only a permissible successive fixed
power capacity but also a permissible short time overload power
capacity.
[0134] The torque pattern with a rectangular shape in FIG. 6(C) is
for a case where the cutting speed (paper feeding speed Vs) is low
or intermediate, and the torque is constant in all the range of the
speed. However, if the cutting speed is high, the torque pattern
shown in FIG. 7 can be employed. If the cutting speed is high, the
lower knife 5 is given a cutting torque of 1.25Txa (this is
referred to as initial-period high cutting torque) which is 1.25
times as large as the torque necessary at the time Tc of initiation
of a cutting operation as shown in FIG. 7. After that, the cutting
torque is decreased to 0.6 times as large as the cutting torque
0.6Txa (this is referred to as middle-period low cutting torque).
Then, in the latter half, the cutting torque is increased again up
to about one time as large as the cutting torque Txa (this is
referred to as terminal-period normal cutting torque). Thus, the
torque has a torque pattern with such a polygonal shape. With this
torque pattern having a polygonal shape, it becomes possible to
realize an accurate cutting operation when the cutting speed is
high. Here, FIG. 7 shows a torque pattern for the lower knife
driving motor 13. The upper knife driving motor 12 has a torque
pattern which has the same shape but is inverse in sign. As a
to-be-given torque pattern, other arbitrary shapes than the above
rectangular shape or the above shape with projections and
depressions are available.
[0135] The initial-period high cutting torque is 1.1- to 1.5-times
cutting torque (1.1Txa to 1.5Txa). The middle-period low cutting
torque is 0.6-times to 0.9-times cutting torque (0.6Txa to 0.9Txa).
The terminal-period normal cutting torque is 0.9-times to 1.1-times
cutting torque (0.9Txa to 1.1Txa).
[0136] Then, on the basis of the stored to-be-given torque pattern,
the to-be-given torque instruction values Txat and Txbt at the
elapsed time t sent from the position computing unit 22 are
calculated. The to-be-given torque instruction value Txbt for the
upper knife driving motor 12 is sent to a torque subtractor 33, and
the to-be-given torque instruction value Txat for the lower knife
driving motor 13 is sent to the a torque adder 36.
[0137] The comparator 31 receives the speed instruction value Vt
sent from the speed pattern generator 24 and the detection speed St
sent from the encoder 14 and compares these values. The speed
deviation Vt-St which is to be increased or decreased, as an
operation result, is sent to an instruction torque computing unit
32.
[0138] The instruction torque computing unit 32 receives the speed
Vt-St to be increased or decreased, sent from the comparator 31,
and computes a rotational torque instruction value Tt to be output
to the upper knife driving motor 12 and the lower knife driving
motor 13. The computed rotational torque instruction value Tt is
output to the torque subtractor 33andthe torque adder 36. In this
case, the output pattern of the rotational torque instruction value
Tt is such as that shown in FIG. 6(C). In this manner, the
comparator 31 and the instruction torque computing unit 32 perform
feedback control.
[0139] The torque subtractor 33 receives the rotational torque
instruction value Tt sent from the instruction torque computing
unit 32 and the to-be-given torque instruction value Txbt sent from
the to-be-given torque pattern generator 25, performs a subtraction
therebetween, and sends the output torque instruction value Tt-Txbt
to be output by the upper knife driving motor 12 to the upper
(preceding) power amplifier 34. In this case, the output torque
instruction value Tt-Txbt has a pattern shown in FIG. 6(E). The
upper power amplifier 34 computes output current based on the
output torque instruction value Tt-Txbt and gives the driving
current to the upper knife driving motor 12.
[0140] On the other hand, the torque adder 36 receives the
rotational torque instruction value Tt sent from the instruction
torque computing unit 32 and the to-be-given torque instruction
value Txat sent from the to-be-given torque pattern generator 25,
and performs an addition therebetween, and sends the output torque
instruction value Tt+Txat to be output by the lower knife driving
motor 13 to the lower (following) power amplifier 37. In this case,
the output torque instruction value Tt-Txat has a pattern shown in
FIG. 6(D). The lower power amplifier 37 computes output current
based on the output torque instruction value Tt+Txat and gives the
driving current to the lower knife driving motor 13.
[0141] The upper (preceding) power amplifier 34 and the lower
(following) power amplifier 37 amplify the torque instructions and
generate actual output current to each servo motor.
[0142] In this case, as shown in FIG. 6(D) and FIG. 6(E), the
to-be-given torque instruction values Txat and Txbt are smaller
than torque Ta, Tb, Tc, and Td necessary for motor acceleration or
deceleration. It is unnecessary to increase the rated capacity of
each motor by giving a cutting force to the upper knife driving
motor 12 and the lower knife driving motor 13. In addition, the
upper power amplifier 34 and the lower power amplifier 37 can have
the same rated capacity.
[0143] In this manner, in the acceleration step (from t0 to t1),
the deceleration step (from t2 to t3), and the standby step (from
t3 to t4), the upper knife driving motor 12 and the lower knife
driving motor 13 operate in synchronism with each other. In the
cutting step of the band-like paper D (from tc to to) or the
contact step of the knives (from t1 to t2), the upper knife driving
motor 12, as shown in FIG. 3, applies force in the direction which
makes the upper knife 4 move backward, that is, in the direction
which pushes the lower knife 5.
[0144] In contrast, the lower knife driving motor 13 applies force
in the direction which makes the lower knife 5 move forward, that
is, in the direction which pushes the upper knife 4. In this
manner, by means of the upper knife driving motor 12 and the lower
knife driving motor 13, torque is given to the upper knife 4 and
the lower knife 5 in the direction in which these knives are
pressed against each other, whereby a cutting force for cutting the
band-like paper D is produced.
[0145] In this case, if the to-be-given torque instruction values
Txat and Txbt, which are given to the upper knife driving motor 12
and the lower knife driving motor 13, respectively, are the same,
torque given to the upper knife driving motor 12 and torque given
to the lower knife driving motor 13 are cancelled. Thus, force
required to increase or decrease the paper feeding speed Vs is not
caused, and hence the paper feeding speed is not influenced. As a
result, only force necessary for cutting is applied, so that
accurate and correct cutting of the band-like paper D is
realized.
[0146] With the above arrangement, when the bank-like paper is cut,
clearance between the upper knife 4 and the lower knife 5 falls
within a permissive range, and adjustment of a cutting force is
facilitated, so that an accurate cutting operation is performed
with high reliability. In addition, even if the upper knife
cylinder 2 or the lower knife cylinder 3 is bent, the upper knife
driving motor 12 and the lower knife driving motor 13 appropriately
give a pressing force necessary for the cutting operation, so that
the upper knife cylinder 2 and the lower knife cylinder 3 with a
small rotational inertial force are realized. This makes it
possible to use knife driving-motors 12 and 13 and power amplifiers
34 and 37 with small capacities.
[0147] In the above description, the cut off apparatus and the
control apparatus for the same are described. However, the present
invention should by no means be limited to the above embodiment,
and various changes or modifications may be suggested without
departing from the gist of the invention. For example, although the
upper knife 4 proceeds the lower knife 5 in the above embodiment,
the lower knife 5 can precedes the upper knife 4.
[0148] Further, the above position computing unit 22, cutting
torque computing unit 23, speed pattern generator 24, to-be-given
torque pattern generator 25, upper knife speed control unit 30,
comparator 31, instruction torque computing unit 32, instruction
torque subtractor 33, lower knife speed control unit 35, and
instruction torque adder 36, are realized in the form of electrical
circuits. However, all of these can be realized as a computer
program (or sequence), and the above computing unit, generator,
controller, comparator, adder, and subtractor can be realized as a
sub-program (or sub-sequence).
INDUSTRIAL USABILITY
[0149] Since it is possible to accurately cut off band-like paper
such as a corrugated fiberboard sheet, the present invention is
considerably useful.
* * * * *