The PET automatic blow molding machine is a two-way str […]
The PET automatic blow molding machine is a two-way stretching process during the blowing process. During this process, the PET chain is bidirectionally extended, oriented and aligned, thereby increasing the mechanical properties of the bottle wall and improving the stretching and tensile resistance. , impact strength, and has a good air tightness. Although stretching helps to increase the strength, it cannot be excessively stretched. The tensile inflation ratio should be controlled: the radial direction should not exceed 3.5 to 4.2, and the axial direction should not exceed 2.8 to 3.1. The wall thickness of the preform should not exceed 4.5 mm.
PET automatic blow molding machine equipment is carried out between the glass transition temperature and the crystallization temperature, generally controlled between 90 and 120 degrees. In this interval, PET is in a highly elastic state, which is quickly blow molded, cooled and shaped to become a transparent bottle.
PET automatic blow molding machine in the blowing process: from stretching to secondary blowing, the two movements are very short, must be adjusted well: stretching start timing, stretching speed, pre-blowing start And the end timing, pre-blowing pressure, pre-blowing flow, etc., if possible, it is best to control the overall temperature distribution of the preform, the temperature gradient of the inner and outer walls of the preform.
In the process of rapid blowing and cooling, induced stress is generated in the bottle wall. For a carbonated beverage bottle, it is resistant to internal pressure and is beneficial, but for hot-filled bottles it is necessary to ensure that it is fully released above the glass transition temperature.