In the two-stage SBM process, tube-shaped preforms are first made by injection molding, cooled to room temperature, and stored until required. They are then reheated to an appropriate temperature distribution above the glass transition temperature of the material and stretch blow molded into bottles using a reheat SBM machine. Reheating produces temperature profiles, both through the thickness and along the length of the tube-shaped preform. The temperature and its distributions in the reheated preform have a strong effect on the stretching and inflation of the preform and the orientation, crystallinity, critical performance characteristics (the mechanical properties, barrier performance, and transparency), and thickness distribution in the bottle. The regions with higher temperature will stretch and blow out faster and thin out more than the regions with lower temperature. The stretching temperature also determines the amount of orientation induced by stretching, which, in turn, affects the properties of the bottle. So, reheating is a decisive factor for the production of high quality bottles in the two-stage SBM process, and it is very important to investigate the temperature evolution within the preform during its reheating. A few efforts have been made to represent the heat transfer inside an infrared oven [16], [17], [18], [19] and [20] but, because of the complexity of the radiative transfer in a transparent preform, the problem still remains open. Moreover, to the knowledge of the authors, in the previous researches on the reheating stage of the two-stage SBM process, the predicted temperature profiles were verified only by measuring the preform surface temperatures [16], [17] and [18].
The current work describes the development of a PC-based temperature acquisition system which was used to measure the transient temperature profiles of an extrusion blow-molded part during its cooling and solidification, and of a reheated preform in SBM. For the former, the temperatures at different locations across the thickness of the cooling part were measured. For the latter, the temperature measurements were carried out at different locations both across the thickness and along the length of the preform.
In the two-stage SBM process, tube-shaped preforms are first made by injection molding, cooled to room temperature, and stored until required. They are then reheated to an appropriate temperature distribution above the glass transition temperature of the material and stretch blow molded into bottles using a reheat SBM machine. Reheating produces temperature profiles, both through the thickness and along the length of the tube-shaped preform. The temperature and its distributions in the reheated preform have a strong effect on the stretching and inflation of the preform and the orientation, crystallinity, critical performance characteristics (the mechanical properties, barrier performance, and transparency), and thickness distribution in the bottle. The regions with higher temperature will stretch and blow out faster and thin out more than the regions with lower temperature. The stretching temperature also determines the amount of orientation induced by stretching, which, in turn, affects the properties of the bottle. So, reheating is a decisive factor for the production of high quality bottles in the two-stage SBM process, and it is very important to investigate the temperature evolution within the preform during its reheating. A few efforts have been made to represent the heat transfer inside an infrared oven [16], [17], [18], [19] and [20] but, because of the complexity of the radiative transfer in a transparent preform, the problem still remains open. Moreover, to the knowledge of the authors, in the previous researches on the reheating stage of the two-stage SBM process, the predicted temperature profiles were verified only by measuring the preform surface temperatures [16], [17] and [18].The current work describes the development of a PC-based temperature acquisition system which was used to measure the transient temperature profiles of an extrusion blow-molded part during its cooling and solidification, and of a reheated preform in SBM. For the former, the temperatures at different locations across the thickness of the cooling part were measured. For the latter, the temperature measurements were carried out at different locations both across the thickness and along the length of the preform.
การแปล กรุณารอสักครู่..
