J. Pac .Sci. Tech.

Vol.20No.4（2011）

Original Paper～～～～～～～～～～～～～～～～～～～～～～～～～～～～

Deformation Behavior of Corrugated Medium During
Wedge Indentation into Heightwise CorrugatedShigeru NAGASAWA*†, Masatoshi FUJIKURA*
Yasushi FUKUZAWA* and Takashi KAJIZUKA**This paper describes the occurrence phenomena of string-like paper dust on the die-cutting processof corrugated paperboard (Cpb). In order to reveal the effect of blade position from the apex of acorrugated medium (CM) on the deformation behavior of the CM, a cutting blade was quasi-staticallyindented to Cpb and the side view of Cpb was observed by using a CCD camera. Through this experiment,
the followings were revealed. (1) Deformation behavior of the CM during the blade indentation wasclassified into three macro groups: M-like form (apex crushing), Z-like form (doubly-folded), and W-likeform (back-side liner and root crushing). (2) Z-like form was subdivided into the three modes C, D, andE; representing the blade moved aside a Z-form due to insufficient folding; the blade just cut off theZ-form, and the blade moved aside the Z-form due to surplus folding, respectively. Five or three modes
were arranged for a half range (in the right or the left) on the setup position X of the blade. (3)Asymmetric structure of the CM wave affects the distribution of deformation modes of the CM withrespect to X. (4) Constraint of Cpb affects the occurrence probability of deformation modes.
Keywords：shear, die cutting, inner flute, blade position, folding, thread-like dust

1. Introduction 1
In the production process of packaging
containers, which are composed of corrugatedpaperboards (Cpb) and/or coated paperboards, theflatbed (the platen) die-cutter is generally used for
cutting off work sheets1, 2). Since the patterndevelopment of packaging containers made by
Cpb is normally standardized in various markets,
the same steel-rule die is apt to be used for a long
cutting duration, more than hundreds of thousandsof times, but less than one million times.
Therefore, the durability of cutting tools and thequality of sheared profiles of work sheets areimportant for advanced production technology of
packaging containers. It is necessary to consider
corrective action on the paper dust to solve any
problem that may occur in the pre/main/postprocessing of a flatbed die-cutting.
In order to clean up and reduce the paper
dusts, setup of dust collectors and manualsweeping actions by human hands are usuallyconsidered. Adding this, brief stops of the flatbed
die-cutter are also necessary for inspecting thequality of die-cutting. Regarding this problem,
when a cutting blade (wedge) is indented to an
inner liner stacked on a heightwise corrugatedmedium (CM), it is empirically known that the

Nagaoka University of Technology, Dept. of Mechanical Eng.,** Rengo Co. Ltd., Packaging Technical Center,†Corresponding author, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan, Tel/Fax: +81-258-47-9701,
Email: snaga@mech.nagaokaut.ac. jp*－ 283 －

Deformation Behavior of Corrugated Medium During Wedge Indentation into Heightwise Corrugated

CM is deformed into Z-like crushed structure.
And the string-like paper dusts are sometimes
generated from the cutting process of the Z-likecrushed CM3). Collected paper dusts actually
include powder-like fine dusts, sliced chips, andstring-like (or thread-like) dusts.
The frequency of occurrence of paper dusts
appears to vary with the processing style,depending on whether it is the flatbed type or therotary type die-cutter2). Furthermore, there appear
to be several causes corresponding to each form
(profile) of the paper dusts, in the flatbed type orin the rotary type. In order to develop any
corrective actions, it is necessary to investigate
the occurrence mechanism of paper dusts.
In this study, therefore, the occurrence of
Z-like crushed CM was statistically investigatedwhen the rectangle-formed specimen ofheightwise Cpb was quasi-statically subjected toindentation of a 42° center-bevelled blade (virginstraight knife) by varying the blade position fromthe apex position of the CM wave. In thisprocess, the side view of Cpb was observed byusing a CCD camera in order to reveal the effectof blade position on the deformation behavior of
the CM.

2. Experimental
2.1

Specimens
Fig. 1 shows the size of a specimen formed ina rectangle. The specimen was made of a
C-fluted board, which was composed of the inner
liner, the outer liner and the CM. Nominal
specification was as follows: height of Cpb: t= 4.0/mm, wave length of the CM: λ= 7.9 /mm; basis
weight of the liners: 170 /gm-2; thickness of theliners: 0.2 /mm; basis weight of the CM: 120/gm-2 and thickness of the CM: 0.2 /mm.

t
40 /mm

10 /mm

Fig.1 Layout and size of specimen
Table1 In-plane tensile properties of specified
raw-material sheets (strain rate:0.28×10-3/s−1)
Raw-material
sheetsYoung’smodulus/GPa

Ult. Tens.
Strength/MPa

Breaking
strain%Liner (MD)

5.51(0.13)

56.7 (1.69)

2.0 (0.12)

Liner (CD)

1.64(0.20)

21.1 (0.77)

5.2 (0.41)

Corrugatedmedium (MD)
Corrugatedmedium (CD)

4.07(0.24)

31.7 (1.39)

1.5 (0.14)

1.22(0.09)

11.1 (0.40)

2.3 (0.29)

Average (standard deviation) for 10 samples

The in-plane mechanical properties, based on
the JIS-P-8113 tensile testing, of the liners and the
CM are shown in Table 1. Here, MD: Machine
direction, CD: Cross machine direction.
Specimens of Cpb were prepared in a room at an
average temperature of 296 K and humidity of
50%RH for 24 hours.

2.2

Experimental condition
Fig.2 shows the schematics of theexperimental apparatus. The upper crosshead had
the cutting-blade mounted on a load cell with the
maximum loading capacity of 10 /kN. Fig.2 (a)shows the structural relation between the lower
counter plate (copper) and the work sheet (Cpb)
subjected to a pushing load by the blade, whileFig.2 (b) shows the setup position e of the blade
from the apex position of the CM wave.
Displacement of the blade was controlled by aservo actuator CYP-3-10 (Shinto Kogio) with theposition accuracy of +/−0.01 /mm.

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J. Pac .Sci. Tech.

The front (outside) liner of the work sheet was
attached to the lower counter plate, the groove of
which has the depth of 1 /mm and the length of
40.5 /mm. The work sheet was fixed at the heightof 4.0 /mm by using a pair of retainer plate inorder to restrict softly the bend-up of the work
sheet. This constraint was here defined as thesoft-fixing condition. In order to confirm the effectof soft-fixing JIG, another plain counter plate(without step-like groove) was prepared, and theretainer plates were removed. This constraint was
defined as the free condition.
The high-carbon steel (SK5) blade4) had thefollowing specification: tip hardness of 690 VHN,
apex angle α of 42°, tip thickness w of 5 /µm,
body thickness of 0.71 /mm, length of 40 /mm,
and peaking height of the blade 5.6 /mm.
Apex angle α
Load cell

Feed velocity
V=0.4 /mms−1
Blade holder
Blade
Retainer plate
Counter plate

Tip thicknessw
Worksheet

Base plate
X-StageVol.20No.4（2011）

The heightwise flute of the work sheet was
adjusted for being parallel to the cutting-blade byusing the CCD camera (Keyence digital
microscope VHX-200, VH-Z35, picture element:
2,110,000 pixel), and the lower base plate wassecondly moved for adjusting the setup position eof the blade by using the X-stage. On theexperiment apparatus, the upper crosshead moved
downward with a feed velocity V of 0.4 /mms-1.
Indentation depth d of the blade was measured bya displacement meter of the servo actuator
CYP-3-10 until the outside liner (lower liner) was
cut off, while the cutting force F /kN (= specimen
width L x line force f /kNm-1) of the blade wasmeasured using the load cell.
Normalized setup position X=e/λ of the blade
was chosen from −0.5 up to +0.5. Here, X=0
corresponded to the condition under which theblade was manually set to the middle position of
the CM wave (on a middle line of the height of
Cpb). The CCD camera was used for recording
video images as shown in Fig.3, in order toobserve the deformation flow in the side view ofthe work sheet during the blade indentation. The
free condition of the work sheet is illustrated in
Fig.3. Sample numbers were 10 for each setup
position X of the blade.

(a) Structure of blade, lower plate and X-stage
Blade

42 °
Cutting blade
Back(inner) side of linereBlade position
Corrugated board

Corrugated medium
Front (outer) side of liner

NominalCCD
cameraHeight t=4.0 /mm

λ=7.9 /mm

10mm

X-stage(b) Details of blade position and work sheet
Fig.2 Schematics of cutting apparatus

Fig.3 Observation unit and cutting apparatus(in case of free condition)－ 285 －

Deformation Behavior of Corrugated Medium During Wedge Indentation into Heightwise Corrugated(a) d/t=0.0(b) d/t=0.5

2 /mm(d) d/t=1.0(c) d/t=0.8

Fig.4 Video photographs of side view of
C-fluted board during blade indentation(Z-like crushing in case of X= +0.1)

3. Results and discussion
3.1 Deformation modes of CM
Fig.4 shows an example of sectional-view
photographs of the C-fluted board subjected toblade indentation at the setup position of X= +0.1
for d/t= 0~1.0. This deformation flow wasrecognized as the Z-like crushing mode from
Fig.4 (c). All the deformation behavior of the CM
was classified with respect to the crushing modes
during d/t= 0.5~1.0 from the video images.
Blade

L

The occurrence of Z-like form and theoccurrence of string-like dust were statisticallyobserved for d/t= 0.8~1.0. Through thisobservation of the crushed CM, the next three
deformation modes, as shown in Fig.5, were
found as the macro group: (i) M-like form (apexcrushing), (ii) Z-like form (doubly-folded), and(iii) W-like form (back-side liner and rootcrushing). When d/t=0.8, the distance L, R or L’,
R’ were measured from the video images asshown in Fig.5. Here, those parameters were
defined as the distance between the blade position
and the cross points of the CM with the level of
d/t= 0.8. Using the ratio of L/R or L’/R’, alldeformation modes were classified to be of sevenkinds as A, B+, C+, D+, E+, F+, G+ for 0 X
0.5, as shown in Table 2. The plus symbol
meant that the crushing occurred at the right-halfzone: 0 X 0.5. Similarly, denoting the minus
symbol as the left-half zone: −0.5
X<0,deformation modes were of six kinds as B−, C−,
D−, E−, F−, G−. Here, G+ is the same as G− dueto the periodicity of the CM wave.
Table 2 Deformation modes of corrugatedmedium (13 kinds of branched state)

Inner liner

R

E

C
D

Counter plate(a) M-like crushing
L’(b) Z-like crushingR’(c) W-like crushingFig.5 Three-classified deformation modes ofcorrugated medium subjected to a wedge
indentation by varying setup position of
blade (in case of 0<X<0.5)

Since the deformation of the CM with A andG(+/−) was perfectly symmetric, the occurrenceof those states was not observed actually.
Therefore, only 10 kinds of deformation modes B(+/−), C (+/−), D (+/−), E (+/−), F (+/−) wereactually observed in the range of −0.5
X

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J. Pac .Sci. Tech.

0.5.
When the CM of the work sheet was crushed
in Z-like form for d/t <0.8, the crushed form of
the CM branched to three deformation modes in
the final state: C, D and E. In the case of Mode
D(+/−), the blade just cut off the doubly-folded
CM (Z-like form) and then two pieces ofstring-like dust were normally generated,
although a piece of string-like dust was
sometimes generated when the one folded part
dynamically escaped from biting of the blade tip.
Fig.6 shows an example of string-like dust
occurred at Mode D+. A folded strip with a widthof 1 /mm was detected as the string-like dust. In
the case of Mode C or E, the blade moved aside
the doubly-folded part without cutting off the CM.
All the modes defined in Table 2 weresynthetically arranged as follows: M-like form
includes A, B(+/−); Z-like form includes C(+/−),
D(+/−), E(+/−); and W-like form includes F(+/−),
G(+/−), respectively.

Fig.6 Example of string-like dust occurred atMode D+

Vol.20No.4（2011）

Through the experiment, the occurrence of
Z-like form appeared in the range of 0.3>X> −0.4
in both the soft-fixing and free conditions. Fig.7
shows the occurrence frequency of thedeformation modes B, D, F and the union mode
{C,D,E} in the case of the soft-fixing constraint.
Fig.8 shows the distribution of frequency of themacro-grouped modes (Z, M, W-like form) withrespect to the setup position of the blade X= e/λ,in the case of the soft-fixing constraint. Similarly,
Fig.9 shows the occurrence frequency of
deformation modes B, D, F and the union mode
{C,D,E} in the free condition case. Fig.10 shows
the distribution of frequency of themacro-grouped modes (Z, M, W-like form) in thefree condition case.
From Figs.7 to 10, the following features
were revealed: (i) Distribution of occurrence
frequency of the deformation modes B, C, D, E, F
was statistically asymmetric concerning the setup
position of the blade X. (ii) In the case of thefree condition, both the distribution of M-like andW-like form tended to scatter widely with respect
to X, as compared to the soft-fixing constraint. (iii)
Distribution of the occurrence frequency of theunion mode {C, D, E} was varied with theboundary constraint. (iv) M-like form tended tooccur at the range of |e| < λ/4.
Due to the periodicity of the CM wave,
Table 3 shows the estimated probability ofrepresentative modes for −0.5<X<0.5. Here, theprobability pi of Mode i was estimated from
Eq.(1), by using the frequency ρi occurred at X
with Mode i (= B,C,D,E,F and so on).

pi = ∫

0.5− 0.5

3.2 Occurrence frequency of crushing form
with fixing condition－ 287 －

ρ i ( X )dX

Eq.(1)

Deformation Behavior of Corrugated Medium During Wedge Indentation into Heightwise Corrugated

λ=7.9 /mm

0.6

0.2

(a) In case of Mode B+ and B-

λ=7.9 /mm

0.6 Mode
D0.4

λ=7.9 /mm

0.8
0.6Mode B-

Mode B+

0.4
0.2(a) In case of Mode B+ and B1.00-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λ(b) In case of Mode D+, D- and Union modes ofC, D, E (+/-)
Frequency of occurence

0.2

Mode D+

0.2

0.8

0.4

0
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λFrequency of occurence

Frequency of occurence

Union modes C,D,E(-)
Union mode C,D,E(+)

Frequency of occurence-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λ0.8

λ=7.9 /mm

0.6

1.0

0

1.0

0.8

M-like form (A, B)

Fig.8 Distribution of large-grouped modes:
Z-like and M-like crushing form with
soft-fixing constraint

Mode B0.4

1.0

Z-likeform(C,D,E)0-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λMode B+0.8

λ=7.9 /mm

0.8
0.6

Union
mode
C,D,E
(-)

Union mode C,D,E(+)

0.4 Mode D-

Mode D+0.2
0-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λMode F-(b) In case of Mode D+, D- and Union modes ofC, D, E (+/-)

0.6
Mode F+
0.4

1.0

0.2
0
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λ(c) In case of Mode F+ and FFig.7 Distribution of deformation modes
occurred at d/t=0.8 with soft-fixing constraint(10 samples for each X measured)－ 288 －

Frequency of occurence

Frequency of occurence

1.0

1.0

Frequency of occurences

From the experiment, since ρA= ρG= 0 for−0.5<X<0.5, the union {A,B} was the same as
Mode B, and also the union {F,G} was the sameas Mode F in Table 3.

Mode F0.8

Mode F+

0.6
0.4
0.2
0
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λ(c) In case of Mode F+ and FFig.9 Distribution of deformation modes
occurred at d/t=0.8 with free condition(10 samples for each X measured)

J. Pac .Sci. Tech.

Frequency of occurences

1.0

Vol.20Z-likeform(C,D,E)

M-like form (A, B)

0.8
0.6
0.4

λ=7.9

0.2

/mm
0

-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Setup position of blade X=e/λFig.10 Distribution of large-grouped modes:
Z-like and M-like crushing form with freecondition(a) Constraint: soft-fixing
C

D

E

C,D,E

Prob. %

10.4 6.6 10.3

Mode(+/-)(b) Constraint: freeCD
E C,D,E

Prob. %

6.1 7.5 14.5

A,B

F,G

27.2 19.4 53.4
A,B

case of the soft-fixing constraint, it was observedthat Mode C or E was not easily transformed toMode D due to the constraint of Cpb.
In actual case of die-cutting process, as Cpb isfixed by a rubber-sponge rule, the crushing formof the CM appears to be affected by the setup
condition of the rubber-sponge fixture. From the
aspect of real-boundary constraint of Cpb, theprobability of Z-like form must be furthermore
investigated.

3.3 Estimation of asymmetric wave formof corrugated medium

Table 3 Estimated probability pi ofrepresentative modes for |X|<0.5
Mode(+/-)

No.4（2011）

F,G

28.0 16.3 55.7

As three modes C, D, E have the possibility
for generating the string-like paper dust, theprobability p{CDE} of the union mode {C,D,E}
appears to be appropriate for watching theoccurrence of string-like paper dust.
From Table 3, it was found that the balance ofthe probabilities pC, pE varied remarkably with theboundary constraint. Regarding generation of thestring-like paper dust, the probabilities pD, p{CDE}of the free condition were a little large, comparedwith those of the soft-fixing constraint.
According to the video data of the CM during
blade indentation for d/t=0.5~0.8, it was foundthat, in case of the free condition, ashallow-crushed Z-like form gradually became adeep-crushed Z-like form, owing to the lateral(horizontal) sliding and the bend-up of Cpb. In the

The crushing form of the CM and the
distribution of each mode with the setup position
X were asymmetric as shown in Figs.7 to 10. The
occurrence of M-like form (apex crushing) was
apt to move on the right side with the origin of
X=0. The neutral position of apex crushing was
expected to lie in the range of 0<X<0.1.

θ L θR
Back side (inner) liner

Front side (outer) liner

Fig.11 Measurement of inclined angles θL, θR
As such the eccentric occurrence of thecrushing form of the CM appeared to be causedby the initial shape of the CM itself; geometricalprofile of the CM was evaluated fromphotographs of a virgin specimen.
Fig.11 illustrates how to measure the inclined
angles θL, θR of the CM. Through the－ 289 －

Deformation Behavior of Corrugated Medium During Wedge Indentation into Heightwise Corrugatedmeasurement of three apex nodes of the CM wave,
the angles θL, θR were calculated for nine
positions. Their maximum and minimum values
were 51.1° and 46.5° respectively. The average
difference between θR and θL measured wasroughly 1° (θRθL+1°).
In order to confirm the crushing stability of
the CM, the flat crush test was applied torectangle-formed specimens (as shown in Fig.1).
10 samples were examined with the feed velocityof 0.4 /mms-1. From the result, two patterns weredetected as shown in Fig.12: (a) 30% of the CM
was tipped up on the left side; (b) 70% of the CM
was upset in symmetry. There was a certain
eccentricity of the CM form for the flat crush test‡
. The occurrence of left side tipping-up appeared
to be caused by the difference between theleft-side and right-side in-plane stiffness of theCM, and also the difference between θL and θR. It
seemed that the left side of the CM was easily
buckled and eventually the apex points of the CM
tended to move on the left side.

10 /mm(a) Tipping up on the left (b) Symmetric upset
Fig.12 Flat crush test of rectangle-formed
specimen (C-fluted board, Width: 10/mm,
Length: 40/mm, Feed velocity:V=0.4/mms−1)
So far, it is concluded that there is correlation between the initial eccentricity of the CMform and the asymmetric distribution of the‡Thisseems to be a reason why a circle-formed
specimen is used for the standard flat crush test
(JIS-Z0403-1).

crushing modes’ occurrence. In other words, if theoccurrence frequency of several modes, such as
Mode B and the union mode {C,D,E}, ismeasured with respect to X and if the distributionof the frequency is asymmetric,
then theeccentricity of the initial CM form can be
estimated from that correlation.

3.4 Cutting load response to crushing mode
Fig.13 shows the cutting load response on the
final stage of d/t= 0.7~1.0 in the cases of X=0, 0.1
and 0.5. From Fig.13(a) and Fig.13(c), it was
confirmed that the starting position, where theblade bit three pieces of compressed sheets, was
d/t 0.87, while the load response of them wasdifferent for each other due to a difference of thestacked order of the outside liner, the CM, and theinside liner.
In the case of X= +0.1, three patterns of load
response were actually detected. They werecorresponded to Mode B+, C+ and D+ as shownin Fig.13 (b).
When the blade bites the Z-like form of theCM, the stacked thickness can be totallyestimated as five times the raw-materials
thickness. From Fig. 13 (b), as the starting
position of Mode D+ was d/t 0.78, this position
approximately corresponded to five times the
raw-materials thickness. It was found that the load
response of Mode C+ behaved as the middle state
between D+ and B+. Since the occurrence
position (d/t) of peaked-line force differed withrespect to Mode D and B, it was found that it waspossible to infer the pattern recognition of those
deformation modes from the position (or thetiming) of peaked load response, if appropriate
sensors were implanted on the blade system5).

－ 290 －

J. Pac .Sci. Tech.

Vol.20Line force f /kNm−1

30
X=0

25

Mode B+/-

1st: OL, 2nd: CM, 3rd: IL

20
15

Sample number: 10
t=4.0 /mm

10
5
0
0.7

0.8
0.9
Indentation depth of blade c=d/t

1(a) In case of X=0, Mode B+/Line force f /kNm−1

30
X=+0.125

Sample number: 9Mode C+
Mode D+
Mode B+20
15

t=4.0 /mm

10

cD: 0.78

50
0.7

cB: 0.87 0.9
0.8
Indentation depth of blade c=d/t

1(b) In case of X=+0.1, Mode B+, C+, D+Line force f /kNm−1

30
25

X=+0.5

Sample number: 10
1st: OL, 2nd: CM, 3rd: IL

20
15

t=4.0 /mm

10

OL: outside, IL: inside liner

0.7

camera. Through this experiment, the followings
were revealed.
(1) Deformation of the corrugated medium(CM) can be classified with three macro-grouped
modes. It is also arranged with five kinds ofactual crushing modes: B (cut off the apex), C(moved aside the Z-form due to insufficient
folding), D (just cut off the Z-form), E (moved
aside the Z-form due to surplus folding) and F(pushed the back-side liner and cut the root).
(2) Distribution of occurrence frequency of
crushing form of the CM was varied with theboundary constraint of Cpb.
(3) In the free condition, the occurrence of
Z-like form was apt to be promoted, as comparedwith the soft-fixing constraint.
(4) Proposed classification and pattern recognition of
deformation mode of the CM are useful for estimating
the initial-asymmetric structure of the CM.
(5) To monitor the load response is useful for
detecting the deformation mode of the CM.

Acknowledgement50No.4（2011）

0.8
0.9
Nomalized indcated depth c=d/t

1(c) In case of X=+0.5, Mode F+/Fig.13 Relationship between cutting line force
and indentation depth of blade (in case of
free condition)

4. Conclusions
A 42° center-bevel blade was quasi-staticallyindented to rectangle-formed specimen ofheightwise corrugated paperboard (Cpb) by
varying the setup position X of the blade, and theside view of Cpb was observed by using a CCD

This work was supported by the JSPS
Grants-in-Aid for Scientific Research, Creativeand Pioneering Research (C) of Grant Number
22560106.

References
1) S. Mizuguchi, (eds), Advanced Technology
on Industrial Packaging and Transportation,
Fuji Techno System, Tokyo, p.239(2002)
2) Tech-times (eds), Advanced Handbook forProcessing of Papers and Boards, Tech-times,
p.261 (1988)－ 291 －

Deformation Behavior of Corrugated Medium During Wedge Indentation into Heightwise Corrugated3) The Middle Japan Technical Committee for
Corrugated Board, Monthly PACK & BOX,
8 (2), p.8 (2005)4) S. Nagae, S. Nagasawa, Y. Fukuzawa,A. Hine, I. Katayama, SOSEI-TO-KAKOU,
45 (524), 742 (2004)

5) S. Suzuki, Y. Fukuzawa, S. Nagasawa,I. Katayama, H. Iijima, SOSEI-TO-KAKOU,
46 (538), 1061 (2005)（原稿受付 2011 年 3 月 2 日）
（審査受理 2011 年 6 月 15 日）

Corrugated paperboard の段筋方向押抜きにおける
中芯変形挙動の観察
永澤 茂*†、藤倉 正俊*、福澤 康*、梶塚 孝士**

本研究は、Corrugated paperboard (Cpb) の押抜き加工における紙粉発生現象を扱っている。Cpbの押抜き過程で、中芯の折れ曲がる変形挙動がどのように発生するのかを明らかにできれば、糸状紙粉の発生頻度を予測できると考えられる。段筋方向に配置されたくさび刃が Cpb に対して押込まれるとき、中芯の折り重なり変形は、刃先と中芯の山波との相対的な位置関係に依存して発生すると考えられる。 そこで本研究では、C 段の Cpb 試験片に対して段筋方向に沿った直状の 42° くさび刃を押し込む実験を行い、 動画によって Cpb の側面を観察して中芯の変形挙動を解析した。
実験で段頂を基準にし左右半周期について刃先位置を変えて、中芯の変形挙動が推移する様子を明らかにした。中芯の変形挙動は、M 形(山頂付近)、Z 形(中芯の重ね折り)、W 形(谷底付近) の3 つに大分類できた。さらに Z 形を細かく 3 つに細分して、帯状紙粉の発生機構を示すとともに、全体を 10 種類の変形様式に分けて整理した。また、試験片の拘束条件に依存して、中芯変形挙動が変化する現象を明らかにした。試験片の拘束条件を変えると段波の横方向の自由度の違いによって M 形、W 形の出現率が顕著に変化するとわかった。
キーワード: せん断、型抜き、中芯、刃位置、折り曲げ、加工－ 292 －