U.S. patent application number 12/714644 was filed with the patent office on 2010-06-24 for cut off apparatus for cutting off corrugated fiberboard web.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Hiroshi ISHIBUCHI, Satoshi MATSUDA, Katsuaki TAKASAKI, Kuniaki WAKUSAWA.
Application Number | 20100154610 12/714644 |
Document ID | / |
Family ID | 37565715 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100154610 |
Kind Code |
A1 |
ISHIBUCHI; Hiroshi ; et
al. |
June 24, 2010 |
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.
Inventors: |
ISHIBUCHI; Hiroshi;
(Hiroshima, JP) ; MATSUDA; Satoshi; (Aichi,
JP) ; WAKUSAWA; Kuniaki; (Hiroshima, JP) ;
TAKASAKI; Katsuaki; (Hiroshima, JP) |
Correspondence
Address: |
KANESAKA BERNER AND PARTNERS LLP
1700 DIAGONAL RD, SUITE 310
ALEXANDRIA
VA
22314-2848
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
37565715 |
Appl. No.: |
12/714644 |
Filed: |
March 1, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12414783 |
Mar 31, 2009 |
7694612 |
|
|
12714644 |
|
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|
10572856 |
Mar 22, 2006 |
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PCT/JP05/08184 |
Apr 28, 2005 |
|
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|
12414783 |
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Current U.S.
Class: |
83/76 ; 83/342;
83/345; 83/76.1 |
Current CPC
Class: |
Y10T 83/04 20150401;
Y10T 83/159 20150401; Y10T 83/4827 20150401; Y10T 83/141 20150401;
Y10T 83/162 20150401; B26D 5/00 20130101; B26D 1/626 20130101; Y10T
83/4836 20150401; Y10T 83/4682 20150401 |
Class at
Publication: |
83/76 ; 83/76.1;
83/342; 83/345 |
International
Class: |
B26D 5/20 20060101
B26D005/20; B26D 1/40 20060101 B26D001/40; B23D 25/12 20060101
B23D025/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2004 |
JP |
2004-260928 |
Claims
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.
Description
RELATED APPLICATIONS
[0001] The present application is a divisional of Ser. No.
12/414,783, filed Mar. 31, 2009, which is a divisional of U.S.
application Ser. No. 10/572,856 filed Mar. 22, 2006, which is a
National Phase of International Application No. PCT/JP05/08184
filed Apr. 28, 2005, and claims priority from, Japanese Application
Number 2004-260928, filed Sep. 8, 2004. The disclosures of all
above listed applications are hereby incorporated by reference
herein in their entirety.
FIELD OF THE INVENTION
[0002] 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
[0003] 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 are 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).
[0004] [Patent document 1] Japanese Patent Application Laid-open
No. 2002-284430
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0005] 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.
[0006] 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
[0007] A cut off apparatus for cutting off band like paper
comprises: 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 paper 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.
[0008] The control 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] According to embodiments of the invention as set forth
herein, 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic front view of a cut off apparatus
according to one preferred embodiment of the present invention;
[0011] FIG. 2 is a section taken along the arrow line A-A of FIG.
1;
[0012] 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;
[0013] 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;
[0014] FIG. 5 is a control block diagram showing a cut off control
device according to the present embodiment;
[0015] FIG. 6(A) through FIG. 6(E) are diagrams each showing a
control pattern for each knife driving motor according to the
present embodiment;
[0016] FIG. 7 is a diagram showing another example of a torque
pattern given by each knife driving motor according to the present
invention; and
[0017] FIG. 8 is a schematic front view showing a previous cut off
apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION
[0018] 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 pre s sure torque
(to-be-given torque) pattern given by each knife driving motor
according to the present invention.
[0019] 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.
[0020] 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.
[0021] 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).
[0022] 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.
[0023] 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 bas
is weight is always applied, the present embodiment 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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 O, 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.
[0029] 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.
[0030] 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 (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 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.
[0031] Here, if each of the upper gear 8 and lower gear 9 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 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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 a 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.
[0043] 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 to 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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 to 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.
[0050] 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.
[0051] 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.
[0052] 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 0.6
Txa (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.
[0053] 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).
[0054] 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.
[0055] 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.
[0056] 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 33 and the 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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
[0067] Since it is possible to accurately cut off band-like paper
such as a corrugated fiberboard sheet, the present invention is
considerably useful.
* * * * *