MEASURING METHOD FOR DRAWDOWN OF MOLTEN PARISON IN DIRECT BLOW MOLDING

摘要

PROBLEM TO BE SOLVED: To measure simply and with high accuracy the status of generation of drawdown by photographing with time the status of dropping of a molten parison to be extruded from a die in the vertical direction and measuring the status of generation of drawdown of the molten parison based on a photographing data. SOLUTION: A molten parison 3 is extruded out of an extruder 1, and the molten parison 3 are cut off on the position of a die outlet at the time of the state of being extruded normally. The extrusion is continued, and a camera 4 is started to operate from the time that the end of the molten parison 3 is passed through a measurement start point and the photographing time of the molten parisons 3 is recorded. The dropping speed and the acceleration speed of respective timings of the parisons 3 are computed by an image formed by the camera 4 based on the data of the length of the parison 3 or the data of end positions at respective photographing times processed and found by an image processing device 7. At what points of time the drawdown is generated and how the drawdown is developed can be grasped accurately by the arrangement.