Preforms and their heating, pre-blowing (position, pres […]
Preforms and their heating, pre-blowing (position, pressure and flow), stretching rods, high pressure blowing (pressure, position) and molds are factors that influence the bottle making machine in the process.
The preform is also called a parison. The PET pellets are injection molded. It requires that the proportion of recycled materials should not exceed 10% and the number of recovery should not exceed two. The preform after injection molding or the preform used after heating must be cooled for more than 48 hours, and the preform used should not be stored for more than 6 months. Different production dates, especially those with too long intervals, cannot be mixed. The main reason is The raw material type of the preform, the proportion of the secondary material mixed in and the residual stress in the preform are different, and these factors have a significant impact on the molding process of the blowing bottle, and should be treated according to the actual situation.
The heating of the preform is done by a heating furnace, which is manually set and automatically adjusted. The height of the heating furnace is preferably about 25 mm, and is about 19.6 mm from the conveying wheel. The preform is continuously run through the whole oven on the conveying wheel, so that the preform is more evenly heated and can be formed better, which overcomes the shortcomings of the previous preform heating and manual rotation and uneven heating. However, if the heating furnace is improperly adjusted, it will cause uneven distribution of the wall thickness of the blown bottle (such as light weight), bottle mouth enlargement, hard neck and other product defects, and even cause mechanical component torsion failure.
The temperature of each area can be adjusted according to the molding condition of the product, and the opening condition of the oven tube should be considered. In addition, the setting of the oven output power also has a large effect on the heating of the preform, which controls the output of the entire oven heat. When it is not turned on for a long time, when it is turned on again, the initial output power should be set higher accordingly, and then gradually reduced to the normal state during normal production. The output power is generally about 80%, especially when the ambient temperature is below 5 °C. The effect is more significant.
The blowing production process also has a certain relationship with the production environment temperature, and the ambient temperature is generally room temperature (about 22 ° C). If the temperature is too high, the product is prone to agglomeration and agglomeration; the temperature is too low, the product performance is unstable when the machine starts, and the specific operation should be adjusted according to actual conditions and experience.