1/25/2024 0 Comments Preforme pet![]() The timing relationship between the stretch-rod and the inflation initiation was found to heavily influence the free-blow bottle shape. removed the mould to blow the preform in free air while recording the process with a high speed camera details of the blowing process and bubble propagation were investigated as a function of process timing. The free-stretch-blow (FSB) analysis is not a novel method of investigating the deformation behaviour from preform to bottle. One way to further examine the bottle kinematics is to remove the mould and record the deformation. then developed a transparent mould made from poly (methyl methacrylate) while successfully recording the bottle shape development measurement of the typical strain rates was not investigated. Inferring the bottle formation from contact switch activation relies heavily on the spacing of the switches and does not reveal the material deformation strains during bottle formation. investigated the kinematics of the bottle formation using linear variable differential transformer (LVDT) switches in the mould surface that were triggered on material contact. Previous attempts have been made to examine the deformation behaviour of the preform within the mould. ![]() Accurately measuring the preform temperature and its effects on the blowing behaviour is critical for understanding the ISBM process. The material temperature also has a significant effect on the stretch-rod reaction force. Research has revealed that the cavity pressure within the developing preform is not taken as the supply line pressure, but in essence is a result of the air mass flow rate and cavity volume, which in turn is relatable to the preform material temperature. A more scientific approach into the effect of process conditions on PET bottles during the ISBM formation must be developed.ĭetermining the process outputs such as the evolving cavity preform cavity pressure and stretch-rod reaction force from the ISBM experiment has been investigated over several years. This in turn can be costly in terms of raw material, mould material, energy and set-up time. As a result the process is a ‘black art’ and can rely heavily on previous knowledge and operator experience. ![]() This manufacturing process is complex with variables such as magnitude of pressure, air flow, preform temperature and stretch-rod velocity all influencing the final bottle thickness and mechanical properties. The pressure inflation occurs in two stages pre-blow (6-10 bar) to form the majority of the bottle shape and final blow (>25 bar) to form the final bottle shape and bottle details. The manufacturing process that has been developed to form the containers is the injection stretch blow moulding (ISBM) process where injection moulded PET preforms are reheated above the glass transition temperature Tg using infrared radiation, placed into a suitable mould and then formed using a combination of linear stretching and air pressure inflation. This is due to its clarity, light weight, strength, recyclability and barrier properties, not to mention the relatively large process window available to the manufacturer. Poly (ethylene terephthalate) (PET) is the dominant material for the manufacture of thin-walled containers. Investigation into the effect on deformation mode, strain rate and final bottle shape provide a basis for full understanding of the process optimisation and therefore how the process inputs may aid development of the preferred optimised container. The unprecedented experimental analysis reveals that the deformation behaviour varies considerably with contrasting process input parameters. Process outputs cavity pressure and stretch-rod force were recorded using at instrumented stretch-rod and preform surface strain mapping was determined using a combination of a unique patterning procedure and high speed stereoscopic digital image correlation. Removing the bottle mould and performing free-stretch-blow (FSB) experiments revealed insight into the bottle forming characteristics at various preform temperatures and blowing rates. ![]() The processes required to form PET bottles are complicated and extensive any development in understanding the nature of material deformation can potentially improve the bottle optimisation process. This paper highlights for the first time a full comprehension of the deformation procedure during the injection stretch blow moulding (ISBM) process of poly(ethylene terephthalate) (PET) containers, namely thin-walled rigid bottles. ![]()
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