Estimation of Bending Characteristics of Creased White ...

Modern Environmental Science and Engineering (ISSN 2333-2581) April 2016, Volume 2, No. 4, pp. 211-216 Doi: 10.15341/mese(2333-2581)/04.02.2016/001 Academic Star Publishing Company, 2016 www.academicstar.us

Estimation of Bending Characteristics of Creased

White-Coated Paperboard Subjected to In-Plane

Compressive Load Using V-Block Fixtures

Shigeru Nagasawa, Quyet Tran Xuan, and Weerayut Jina

Nagaoka University of Technology, Japan

Abstract: This research work deals with the development of simple evaluation method of creasing characteristics of coated paperboard. The recent-developed testing device (CST, crease stress tester) is able to control the bending rotation speed of the creased part of a worksheet and its sleeping time at a specified angle position. Although the CST is a high grade equipment and useful for analyzing the bending characteristics, while the cost performance of equipment for simply having assurance of crease stiffness is another problem. The authors have developed a simple evaluation method for knowing the creasing characteristics on a folded line of paperboard, which is subjected to an in-plane compressive load by using a set of V-block fixtures. Through the bending experiment of creased paperboard, the proposed V-Block based estimation method has been compared with some analysis results based on the CST, and its effectiveness was revealed. The primary results were as follows: (1) The buckling strength as the maximum compressive load is characterized with respect to the nominal shear strain (normalized scoring depth of crease). (2) The transitional point as variation tendency of compressive load (by the V-Block) well coincides to the disappearance of peak bending moment of CST. (3) The equivalent bending moment of V-Block well coincides to the CST based bending moment resistance when choosing a certain large folding angle. (4) The proposed V-Block method can be effectively used for a certain large range of folding angle.

Key words: bending moment, folding strength, de-lamination, shearing, buckling, simple evaluation technique

1. Introduction

Coated paperboard is considered to be a fundamental

material for the packaging industry due to its

advantages such as high strength-to-weight ratio, high

surface smoothness, printability, sustainability,

recyclability. To convert paperboard into a packaging

container, the printed paperboard is subjected to cutting

and creasing processes [1]. The aim of these two

processes is to convert the printed paperboard into a

blank form before forming a glued box. The blank is

folded and glued to obtain a packaging product. In this

forming process, appropriate spring back effect of

creased part is necessary for processing in an automatic

Corresponding author: Shigeru Nagasawa, Ph.D.,

Professor, research areas/interests: material processing, form cutting, sheet bending. E-mail: [email protected].

folder-gluer machine, while the creased line must be

stably folded without any surface failure. Therefore, an

evaluation method and assurance of folding strength of

creased line are important. Quasi-static folding

stiffness with respect to the indentation depth of the

creaser was reported and also the crease deviation

effect on the folding deformation of creased

paperboard was discussed [2, 3]. For the past decade, a

couple of new bending strength testers were developed

to seek the bending moment and also to record the side

view image of a creased part during a repeated folding

[2, 4]. The recent-developed testing device (CST,

crease stress tester) is able to control the bending

rotation speed of the creased part of a worksheet and its

sleeping time at a specified angle position [5, 6].

Although the CST is a high grade equipment and useful

for analysing the bending characteristics, while the cost

Estim

212

performance

of crease stif

This resea

simple evalu

coated pape

simple evalu

characteristi

subjected to

set of V-

experiment

V-block bas

with some a

effectivenes

2. Experim

2.1 Pre-proc

The test p

rectangle for

basis weight

20 mm, len

(0.424-0.434

nominal she

size effect, a

which had a

were the sam

were used fo

loading test,

for the V-Bl

strength (no

MD (machin

21.3 MPa in

JIS-P8113 (

boards were

296 K and a

Fig. 1 sh

specimen us

with a radius

with the rubb

The heig

creasing rule

was 7 mm. W

mation of Ben

e of equipmen

ffness is anot

arch work de

uation method

erboard. The

uation metho

ics on a folde

o an in-plane

block fixtur

of creased

sed estimation

analysis resul

s was reveale

mental Con

cessing of Spe

pieces (type L

rmed white co

t ρ = 350 g/m

gth of L = 4

4) mm, for

ear strain. For

another test p

length of L =

me as the ty

for the CST te

while the typ

ock based loa

ominal break

ne direction a

n CD (cross

(feed velocity

kept in a roo

a humidity of

hows the sc

sing a round

s of r = 0.35 m

ber fixtures (

ht difference

e was 1.4 mm

When the cre

nding CharacCom

nt for simply

ther problem.

eals with the

d of creasing

e authors ha

od for know

d line of pape

compressive

res. Throug

paperboard

n method ha

lts based on

ed.

ndition and

ecimen

L) were prepar

oated paperbo

m2), which ha

40 mm, and t

each cond

r a compariso

pieces (type S

= 20 mm, and

ype L. The ty

esting and th

pe S test piece

ading test. Th

ing stress) w

as paper mak

machine dire

y V = 0.05 m

om which had

50%RH.

oring state o

d-edge knife

mm, thicknes

(shore hardne

e (step) of r

m, while the

asing rule is i

cteristics of Cmpressive Loa

having assura

.

e developmen

characteristic

ave develope

wing the crea

erboard, whic

e load by usin

gh the bend

d, the propo

s been comp

the CST, and

d Method

red as 5 piece

oard (the nom

ad a width of

thickness of

dition of cho

on of geometr

S) were prep

d other condit

ype L test pi

he V-Block b

es were used

he in-plane ten

was 44.2 MP

king process)

ection), based

mm/s). All p

d a temperatur

of a paperb

(a creasing

ss of b = 0.71

ess 40 A).

rubber from

height of rub

indented to th

Creased Whitead Using V-B

ance

nt of

cs of

ed a

asing

ch is

ng a

ding

osed

ared

d its

es of

minal

W =

0.43

osen

rical

ared

tions

ieces

ased

only

nsile

Pa in

and

d on

aper

re of

oard

rule

mm)

the

bber

he

Fig.

pap

she

Thi

stra

the

was

crea

resp

she

0.6,

cho

emp

2.2

F

exp

bas

exa

θan

wid

ms.

cree

rota

the

0 s

velo

to

mat

load

e-Coated PapBlock Fixtures

. 1 Schematic

perboard, the

aring strain

is quantity γain [1, 6]. Als

thickness of

s also empiri

aser direction

pect to the m

ar strains γ w

, 0.7, 0.8, 0

osen as V =

pirically cons

Measuremen

Fig. 2 shows a

perimental ap

ic folding re

ample of the

nd a bending

dth) M. The sa

Since the p

ep characteri

ation velocity

stopping tim

s at a trackin

ocity of ω =other reports

tching to the

d testing.

perboard Subs

cs of scoring ap

expression:

as a geometr

is defined h

o, using the p

the creasing r

ically chosen

n angle φ wa

machine direc

were chosen a

.9, 1.0, whil

0.0167 mm⋅sidered from

nt of Bending

a schematic d

pparatus [4-6]

esistance (as

relationship

line momen

ampling time

paperboard h

istics during

y ω of the fixtu

me before retu

ng position o

0.05 rps was

s [6], but ch

feed velocity

bjected to In-

pparatus.

(2d/B) = γ is

rical gradien

here as the no

paperboard th

rule b, the gro

n as 2t+b = 1

as chosen as

ction (MD).

as 0, 0.1, 0.2,

le the feed v

⋅s−1. The ran

0.0 up to 4t/B

Moment Bas

diagram of th

] used for co

a standard).

between a f

nt (resistance

of M, θ was

has viscous e

the folding

ure was set to

urning back w

of Θ = 90°.

relatively slo

hosen for ap

y of V-Block

Plane

s the average

nt of scoring.

ominal shear

hickness t and

oove width B

1.6 mm. The

0°, 90° with

The nominal

0.3, 0.4, 0.5,

velocity was

nge of γ was

B.

sed on CST

he CST based

onfirming the

Fig. 3 is an

folding angle

e for the unit

chosen as 10

elasticity and

process, the

o 0.05 rps and

was set to tep=

The rotation

ow, compared

pproximately

compressive

e

.

r

d

B

e

h

l

,

s

s

d

e

n

e

t

0

d

e

d

=

n

d

y

e

Estim

Fig. 2 Bendi

Fig. 3 Analy

2.3 Measure

Fixtures

Fig. 4 sh

specimen mo

a general v

vertical dist

initially set

this V-Bloc

velocity 1 m

to the inside

compressing

compressive

the displace

maximum d

while it wa

rotation vel

90/360/5.9s

0.021 rps for

loading respo

mation of Ben

ing test appara

ysis parameter

ement of Com

hows an exa

ounted on the

view of com

tance of upp

up as LV0 =

ck stand was

mm/s until the

e surface of

g test, the

e load per uni

ement δ =

displacement

as 11.8 mm

ocity of fold

= 0.042 rps

r L = 40 mm. F

onse when ch

nding CharacCom

atus using CST

rs on bending r

mpressive Loa

ample of de

e V-Block sta

mpressive lo

per and lowe

L. The speci

s compressed

deflected spe

V-Blocks. In

relationship

it width FV/W

LV0−LV wa

was 5.9 mm

for L=40 m

ding was est

for L = 20

Fig. 5 shows

hoosing γ = 0


T.

response diagr

ad Using V-B

eflected state

and apparatus

oading test.

er V-blocks

imen mounte

d under the

ecimen conta

n this duratio

p between

W = fV N/mm

as measured.

for L = 20 m

mm. The ave

timated as ωmm, while ωan example o

0 (none scored


am.

Block

e of

s and

The

was

ed in

feed

acted

on of

the

m and

. Its

mm,

rage

ωV =

ωV =

f the

d).

(a) In

Fig.stan

Fig.


nitial set up of spe

(c) V-B

. 4 Detail of nd apparatus.

. 5 V-Block b

perboard Subs

ecimen (b) Loaded

lock stand and lo

set up of spec

based load resp

bjected to In-

d and deflected st

oading test appara

imen and layo

ponse diagram.

Plane 213

ate of specimen

atus

out of V-Block

.

3

k

Estim

214

The maximu

as the bucki

All the spec

shown in Fig

upper V-blo

deflected sp

choosing the

30, …, 80°.

lateral defle

compressive

moment of V

The equiv

of (MV, αV)

based on CS

folding con

corresponde

peak bendin

methods (CS

discussed fo

through the p

3. Results

3.1 V-Block

Moment of C

Fig. 6 sho

use of CST,

γ = 0-1.0. T

initial gradie

several repo

the peak of

Seeing Fig. 6

MP1 is estim

stability is p

Fig. 7 sh

V-Block stan

found that fV

0.4. Namely

strongly rela

resistance, w

mation of Ben

um line load f

ing strength f

cimens were

g. 4(b), due to

ock. Using a

pecimen wa

e folded angl

. Through th

ection δV (sh

e line force

V-Block MV w

MV =

valent bending

was compare

ST when αV

ndition: θ <ed to the prio

ng moment M

ST and V-Blo

or a sort of la

peak bending

and Discus

Based Maxim

CST

ows the bend

, when chang

The first peak

ent C1 (shown

rts [4, 7]. Fro

f MP1 genera

6, the critical

mated as γ performed for

hows the m

nd in terms of

Vpeak extremel

y, the variat

ated to the di

which is char

nding CharacCom

fVpeak = FVpeak

for the nomin

e folded on t

o the protecto

a digital vide

as recorded

le αV such a

his video reco

hown in Fig

fV, the equ

was estimated

fVδV

g moment res

ed with the re

> 10° and γ < 10°, γ <

or zone to th

MP1 [7], the co

ock compress

rge folding s

g moment.

ssion

mum Load an

ding moment

ging the nom

k bending mom

n in Fig. 3) w

om the reports

ally disappea

condition of

= 0.5-0.6 a

r γ > 0.4 in th

maximum lin

f nominal she

y decreased a

tion of buck

isappearance

racterized by


k/W was dete

nal shear strai

the right sid

or mounted on

eo camera, e

when discre

as 10, 15, 20,

ording, using

g. 4(b)) and

uivalent ben

d as Eq. (1).

sponse compo

esponse of (M

γ > 0.5. Since

0.5 empiric

he occurrenc

omparison of

ive load test)

tate after pas

nd Peak Bend

t response by

minal shear st

ment MP1 and

were discusse

s, it is known

ars for γ >f disappearanc

and the ben

his work.

e load fVpeak

ear strain γ. It

at this zone fo

kling strengt

of peak mom

the delamina


ected

in γ.

de as

n the

each

etely

, 25,

g the

the

ding

(1)

osed

M, θ)

e the

cally

ce of

f two

was

ssing

ding

y the

train

d the

ed in

n that

0.4.

ce of

ding

k of

was

or γ >

th is

ment

ation

of m

of p

fVpe

cha

of i

type

spe

exp

3.2

V-B

F

rela

equ

type

com

Fig.mom


multiple plies

practicality, i

eak is useful

aracteristics, w

insufficient s

e L specime

cimen cramp

plained from t

Comparison

Block and CST

Fig. 8 shows

ationship be

uivalent bend

e S specime

mpressive loa

. 6 Relationsment using CS

perboard Subs

s and bulge si

it is revealed

for estimatin

when varying

scoring), the

en is a quart

ped by the V-

the Eulerian t

n of Equivale

T

some repres

etween the

ing moment

en (L = 20

d test. Here, a

(a) In case of φ

(b) In case ofship between rT.

bjected to In-

ize [4, 7]. Fro

d that the mea

ng the bend

g γ. When γ <buckling str

ter of that o

-Block stand.

theory of pilla

ent Bending M

sentative exam

folding ang

resistance M

0 mm) on t

as a reference

φ = 90°

f φ = 0° rotation angle

Plane

om the aspect

asurement of

ding moment

< 0.4 (in case

rength of the

f the type S

. This can be

ar.

Moment with

mples of the

gle αV and

MV using the

the V-Block

ed level, the

e and bending

t

f

t

e

e

S

e

h

e

d

e

k

g

Estim

Fig. 7 Relatdepth) and V-Block stand

bending mo

drawn in thi

bending mo

with the ben

angle αV is

peak of MV o

scoring cros

M(θ = 90°)

CST when γbased M(θ =moment MV

When altern

mm), the pe

was earlier t

1.25

1.0

0.75

0.5

0.25

0.1

mation of Ben

(a) In ca

(b) In ctionship betwemaximum lin

d.

oment resistan

s diagram. It

ment MV of V

nding momen

larger than 5

occurred at αss direction

is nearly equ

γ > 0.4, we c

= 90°) as the

for αV = 60°-

natively using

eak of MV occ

than that of th

nding CharacCom

ase of φ = 90°

case of φ = 0° en nominal shne load (buck

nce of CST

is revealed th

V-Block stan

nt M of CST

50° but small

αV = 25°-35°.

to MD: φ =al to M(θ = 8

can estimate t

e value of eq

-80° in the ca

g the type L s

curred at αV

he type S spec


hear strain (scoking strength

(θ, M) was

hat the equiva

nd well coinc

when the fold

ler than 80°.

It differs with

= 90°, 0°. S

80°) in the cas

the value of C

quivalent ben

ase of L = 20 m

pecimen (L =

= 15°-25° w

cimen, while


oring h) in

also

alent

cides

ding

The

h the

Since

se of

CST

ding

mm.

= 40

which

the

Fig.

and

0.04


. 8 Comparis

d V-Block stand

42 rps).

Ben

ding

mom

ent

M, M

VN

m/m

Ben

ding

mom

ent

M, M

VN

m/m

Ben

ding

mom

ent

M, M

VN

m/m

Ben

ding

mom

ent

M, M

VN

m/m

perboard Subs

(a) φ = 0°, γ

(b) φ = 90°,

(c) φ = 0°, γ

(d) φ = 90°, son of bending

d (CST: ω = 0

Foldin

(θ, M)

Foldin

(θ, M)

Foldin

(θ, M)

Foldin

(θ, M)

bjected to In-

γ = 0.5

γ = 0.5

γ = 0.7

γ = 0.7 moment respo

.05 rps, V-Blo

ng angle θ, αV

(αV, MV

ng angle θ, αV

(αV, MV

ng angle θ, αV

(αV,

)

ng angle θ, αV

(αV, MV)

Plane 215

onse with CST

ck stand: ωV =

V /°

V)

V /°

V)

V /°

MV)

V /°

)

5

T

=

Estimation of Bending Characteristics of Creased White-Coated Paperboard Subjected to In-Plane Compressive Load Using V-Block Fixtures

216

value of MV well coincided to the value of CST based

M for θ = 40°-80°. Here, since the type L specimen

was investigated under ωV = 0.021 rps (slower rotation

velocity), it seems to be affected by the relaxation

(visco-elastic) property of specimen. Synthetically

seeing, it is found that the type L specimen is also

useful for predicting the CST based bending moment

M(θ = 90°).

4. Conclusions

An in-plane compressive load test of a creased

white-coated paperboard of 0.43 mm thickness was

investigated by varying the nominal shear strain γ =

0.0-1.0 using a set of upper/lower V-Block fixtures

(V-Block stand).Here, two kinds of scored specimens

(length of 20 mm, 40 mm) were chosen under

considering two creasing directions (across to MD: φ =

90°, parallel to MD: φ = 0°). Through this in-plane

compressive loading, the specimen was structurally

buckled and folded until to contact with the inside

surface of V-Block stand. V-Block based bending

characteristics were compared with CST based bending

characteristics which was carried out without any

in-plane compression. The obtained results were as

follows:

(1) At the prior zone (the folding angle αV < 20°-35°)

to the peak occurrence of equivalent bending moment

MV, the equivalent bending response (αV, MV) is

obviously different from the CST based bending

response (θ, M), due to the in-plane (axial)

compressive stress.

(2) The buckling strength as the maximum line load

fVpeak is characterized with respect to the nominal shear

strain γ. The transitional point as variation tendency of

fVpeak (by the V-Block stand) coincides to the

disappearance of peak bending moment MP1 of CST.

Using the specified white-coated paperboard, such the

critical nominal shear strain was estimated as γ =

0.5-0.6. As another supplementary item, the prior zone

of γ = 0.4 was related to the folding stability for a large

folding angle (such as 50° < θ < 90°), while γ =

0.5-0.6 was understood as the actualized folding

stability (a sufficiently scored, delaminated state).

(3) The equivalent bending moment MV well

coincides to the CST based bending moment resistance

M when choosing 50° < αV < 80°. The proposed

V-Block method can be effectively used for a certain

large range of folding angle.

Acknowledgements

This work was supported by a fund for developing a

core of excellence as innovation and branding project,

from the GIGAKU Innovation Promotion Center, NUT,

2012-2014.

References

[1] J. M. Kirwan, Handbook of Paper and Paperboard Packaging Technology, Wiley-Black Well, 2013, pp. 280-292.

[2] S. Nagasawa, Y. Fukuzawa, D. Yamaguchi, S. Nagae, I. Katayama and A. Yoshizawa, Deformation characteristics of on creasing of paperboard under shallow indentation, in: Proceedings of 10th International Conference on Fracture (Advances in Fracture Research, Elsevier Sci.), Article ID: ICF10-0202-1-6, Hawaii, USA, 2001.

[3] S. Nagasawa, R. Endo, Y. Fukuzawa, S. Uchino and I. Katayama, Creasing characteristic of aluminum foil coated paperboard, Journal of Materials Processing Technology 201 (1-3) (2008) 401-407.

[4] S. Nagasawa, M. Nasruddin and Y. Shiga, Bending moment characteristics on repeated folding motion of coated paperboard scored by round-edge knife, Journal of Advanced Mechanical Design, Systems, and Manufacturing 5 (4) (2011) 385-394.

[5] Web-1, Katayama Steel Rule Die Inc., Crease Stress TesterCST-J-1, accessed on May, 2013, available online at: http://diemex.com/sale/cst.html.

[6] S. Nagasawa, S. Ozawa and Y. Fukuzawa, Effects of folding numbers, scoring depth and bending velocity on bending-moment relaxation of creased paperboard, Mechanical Engineering Journal 2 (1) (2015), Article ID: 14-00346-1-9.

[7] S. Nagasawa, Y. Fukuzawa, T. Yamaguchi, S. Tsukatani and I. Katayama, Effect of crease depth and crease deviation on folding deformation characteristics of coated paperboard, Journal of Materials Processing Technology 140 (2003) 157-162.

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