Optimization Design of PET Bottle Stretch Blow Molding Based on Orthogonal Test

doi:10.19491/j.issn.1001-9278.2020.06.012

Abstract

Abstract:

Aiming at the defect of small wall thickness near the bottom end of some molded PET bottles, a Polyflow^? simulation software was adopted to perform a numerical simulation for the stretch blow molding process of PET bottles. The interactive orthogonal test method was used to optimize the combination of process parameters including the heating temperature of parison, the stretching speed of rod, pre?blowing pressure, delay time and high blowing pressure so as to improve the minimum thickness and uniformity of the bottle. An optimum combination of process parameters was achieved when the delay time was set as 0.06 s, the stretching speed as 1.6 m/s, the pre?blowing pressure as 0.7 MPa, and the heating temperature was set as 110 °C. After the process parameters were optimized, the minimum wall thickness and wall thickness uniformity increased by 28 % and 63%, respectively.

Key words: stretch blow molding, numerical simulation, interaction, orthogonal test, process parameter

CLC Number:

TQ320.66

Liangxian LIU, Zhihua FENG, Chunxue HU, Jinan GE. Optimization Design of PET Bottle Stretch Blow Molding Based on Orthogonal Test[J]. China Plastics, 2020, 34(6): 73-79.

Figures/Tables 17

Fig.1. Parison and bottle moulds

Fig.2. Changes in stretching speed and pre?blowing pressure

Fig.3. Comparison of bottle wall thickness distribution

Fig.4. Thickness distribution against different rod diameters

Fig.5. Thickness distribution against different rod shapes

Fig.6. Contact between different stretching rods and parisons

Fig.7. Thickness distribution curves at different stretching speed

Fig.8. Thickness distribution curves at different delay time

Fig.9. Thickness distribution curves at different high blowing pressure

Fig.10. Pre?blown finished molding drawing

Fig.11. Thickness distribution curves at different pre?blowing pressure

Fig.12. Thickness distribution curves at different temperature of parison

水平	因　　素
水平	拉伸速度（A）/m?s^-1	延迟时间（B）/s	预吹压力（C）/MPa	瓶坯温度（D）/℃
1	1.4	0.04	0.7	100
2	1.6	0.06	0.9	110

Tab.1. Horizontal table of orthogonal test factors

试验序号		A	B	A×B	C	A×C	B×C	D	最小厚度/mm	均方差值
1		1	1	1	1	1	1	1	0.125	0.025
2		1	1	1	2	2	2	2	0.132	0.029
3		1	2	2	1	1	2	2	0.164	0.014
4		1	2	2	2	2	1	1	0.159	0.016
5		2	1	2	1	2	1	2	0.142	0.022
6		2	1	2	2	1	2	1	0.144	0.024
7		2	2	1	1	2	2	1	0.165	0.011
8		2	2	1	2	1	1	2	0.163	0.015
最小壁厚	k₁	0.145	0.136	0.146	0.149	0.149	0.147	0.148
	k₂	0.153	0.163	0.152	0.150	0.150	0.151	0.150
	R	0.008	0.027	0.006	0.001	0.001	0.004	0.002
均方差值	k₁	0.021	0.025	0.020	0.018	0.020	0.020	0.019
	k₂	0.018	0.014	0.019	0.021	0.020	0.020	0.020
	R	0.003	0.011	0.001	0.003	0.000	0.000	0.001

Tab.2. Interactive orthogonal test scheme and test results

Fig.13. B and C interaction binary figure

Fig.14. Thickness distribution curves before and after optimization

因素	B₁	B₂
C₁	0.134	0.165
C₂	0.138	0.161

Tab.3. B and C interaction binary table

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