? ? Blowing machine bottle blow molding process is a two-way tensile process, in this process, the pet chain is bidirectional extension, orientation and arrangement, thereby increasing the mechanical properties of the wall of the bottle, improve the tensile, tensile, impact strength, and good air tightness. While stretching helps to improve the strength, but also can not be over stretched, to control the ratio of tensile blow: radial not more than 3.5 ~ 4.2, axial not more than 2.8 ~ 3.1. The wall thickness of the bottle blank should not exceed 4.5mm.
? ?The bottle blowing is between the glass temperature and the crystallization temperature, which is generally controlled between 120 and 90 degrees. PET in this interval is shown as a high elastic state, which is a transparent bottle after blow molding and cooling. In one step, the temperature is determined by the length of the cooling time of the injection molding process (such as Aoki bottle blowing machine), so to linking the injection blowing the relationship between two stations.
? ?Blow molding process are: stretch blow two times, the three action time is very short, but be sure to cooperate well, especially the first two steps to determine the overall distribution of the material, blowing the bottle quality. Therefore to regulate: tensile starting time, drawing speed and pre blowing starting and ending time, pre blowing pressure, pre blowing flow, if possible, it is best to preform the overall temperature distribution control, on the outer wall of the inner bottle parison temperature gradients.
In the process of rapid blow molding and cooling, there are induced stress in the bottle wall. For carbonated beverage bottle, and it can be resisting inner pressure, is good, but for hot filling bottles, to ensure the above their glass transition temperature make it fully released.
? ?Common problems and Solutions
1 on the thickness of the thin: to delay the time to blow, or reduce pre blow pressure, reduce gas flow.
2 under the thick thin: in contrast to the above.
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3 fold bottleneck: pre blow too late or pre blow pressure is too low, or the cooling is not good.
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4: white bottle blank cold; stretch; pre blow early or pre blow pressure is too high.
5 bottle at the end of a magnifying glass phenomenon: the bottom of the bottle is too much; pre blowing too late, pre blowing pressure is too low.
6. The bottom of the bottle there are wrinkles: at the bottom of the temperature is too high (at the gate cooling); pre blowing too late pre blowing pressure is too low, the flow is too small.
7 the whole bottle is cloudy (opaque): cooling is not enough.
8 local white: excessive tension, the temperature is too low, or pre blow too early, or hit the stretch rod.
9 bottle bottom eccentric: with the bottle blank temperature, stretching, pre blowing, high pressure blowing may have a relationship. Reduce the bottle blank temperature; speed up the drawing speed; check the gap between the pull rod head and the bottom mold; delay the pre blow, reduce the pre blow pressure; delay the high pressure blow; check whether the bottle blank is eccentric.
bottle blowing machine |SNTO|
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