Instrumentation and Modelling of Injection Stretch Blow Moulding

Dr. Gary H Menary, Mr. Yannis Salomeia and Prof. Cecil G Armstrong

School of Mechanical and Aerospace Engineering

Queen’s University of Belfast, N Ireland

�Aim of research

�Data acquisition principle & equipment

� Pre-form temperature measurements

� Results from industrial trials

� Modelling of ISBM

� Conclusions

OUTLINE

Aim

SBM instrumentation schematics

Preform

MouldLVDT

Stretch Blow Moulding Machine

Force sensor & pressure sensor

Bridge

Ethernet

link

DAQ

Receive

Data

Logging

Data

Processing

& Data Analyze

Results

Presentation

SBM Machine proximity

SC

Mould instrumentation

Switch tips

Sensors holes

• Low force activating sensors (30cN)

• 1 ms acquisition resolution

• 30 mm distance between sensors

• on/off output

Preform and Bottle characteristics

Weight Preform

height

Axial

Stretch

Ratio

Radial

Stretch

Ratio

Overall Stretch Ratio

(g) (mm)

18.5 90 3.7 3.7 13.8

28 101.5 3.7 3.2 12

D

L

l

d

Preform Temperature: IR temperature rig

Displacement

sensor

Sliding mechanism

IR sensors

preform

Patent Pending

Typical temperature measurements

temp-int-low

95

100

105

110

115

120

125

130

0 10 20 30 40 50 60

disp

tem

p int

Poly. (int)

80

85

90

95

100

105

110

115

0 10 20 30 40 50 60

tem

p

disp

temp-ext-low

Series1

Poly. (Series1)

Interior temperature External temperature

DOE on process parameters

Full factorial DOE

0 – parameter value set on low

1 – parameter value set on high

DOE # Temperature Pressure Timing Flow

1 0 0 0 1

2 0 0 0 03 1 0 0 1

4 1 0 0 05 1 0 1 1

6 1 0 1 07 0 0 1 1

8 0 0 1 09 0 1 0 1

10 0 1 0 011 1 1 0 0

12 1 1 0 113 1 1 1 1

14 1 1 1 015 0 1 1 1

16 0 1 1 0

Typical Output from Data Acquisition device

Mould contact sensors

Data

sw7sw6sw5sw4sw3sw2sw1

320

300

280

260

240

220

200

Boxplot of sw1, sw2, sw3, sw4, sw5, sw6, sw7

Data

C23C22C21C20C19C18C17

330

320

310

300

290

280

270

260

250

240

Boxplot of C17, C18, C19, C20, C21, C22, C23

Data

C7C6C5C4C3C2C1

320

300

280

260

240

220

200

Boxplot of C1, C2, C3, C4, C5, C6, C7

DOE 1 DOE 2 DOE 3

� the bubble has an

uniform expansion;

consecutive triggers

� the bubble develops in

two locations; indicating

development of a cold ring

and/or a wrinkle

� the bubble has an

uniform expansion; pre-

blow creates more of the

bottle volume

� Seven equidistant sensors along the length of the mould

cold ring

wrinkle

DOE Temperature Pressure Timing Flow

1 0 0 0 1

2 0 0 0 03 1 0 0 1

Building a picture of preform evolution inside the mould

1

2

3

4

5

6

7

Final

blowPre-

blow

φ

1

2

3

4

5

6

7

Final

blow

Pre-

blow

DOE 1 DOE 8

Slippage on the mould wall

a)

b) c)

Slippage on the mould wall

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

SE

NS

OR

5

-2

-1

0

1

2

3

4

5

6

7

8

DOE

SLIPPAGE

SENSOR5

SENSOR4

SENSOR3

SENSOR2

SENSOR1

Finite Element Modelling

• Commercial FEA package, ABAQUS used

– General purpose FEA package that can be customised

• CAD Geometry representing the preform, mould and stretch rod

• Model to represent the material behaviour

– PET behaves in a complex non linear viscoelastic manner

• Process conditions

– Pressure, temperature, rod displacement

• Interaction properties between preform and mould/rod

– Friction/heat transfer

DOE 3 - simulation

DOE3 – Validation: Pressure and stretch rod force

TempDOE3 > TempDOE1

DOE9 – Simulation

DOE9 – Validation: Pressure and stretch rod force

Supply pressureDOE9 > Supply pressureDOE1

Validation: Thickness distribution

0.2

0.3

0.4

0.5

0.6

0 20 40 60 80 100 120 140 160 180 200 220

Vertical Distance from base region (mm)

Th

ickn

ess D

istr

ibu

tio

n (

mm

)

Thickness_Experimental_DOE9

Thickness_Simulation_DOE9

0.2

0.3

0.4

0.5

0.6

0 20 40 60 80 100 120 140 160 180 200 220

Vertical Distance from base region (mm)

Th

ickn

ess D

istr

ibu

tio

n (

mm

)

Thickness_Experimental_DOE3

Thickness_Simulation_DOE3

Conclusions

� Capable of deploying a wireless data acquisition system on an industrial

ISBM machine

□ Measurements of pressure, stretch rod force and displacement.

□ Bubble kinematics

□ Air Temperature

□ Internal and External preform temperature distribution

□ Numerical simulation of ISBM process has been developed using

commercial FEA packages ABAQUS

□ Validation of pressure and stretch rod force

□ Thickness predictions still not ideal

□ Material model – strain hardening too soon?

□ Further understanding of contact conditions is required to improve

the simulation

Acknowledgements

• Logoplaste

– For performing ISBM trials

• Apt_Pack project partners