Plastic hollow containers are widely used in beverage, medicine, cosmetics, food and chemical industries due to their light weight, low price and high safety. They attract more manufacturers to choose plastic containers instead of glass containers.

Today's plastics industry equipment, molds, and raw materials are all unfolded in front of us, new technologies and new applications are emerging one after another, and the field of plastic hollow molding is also fruitful. With the soaring world oil prices, the price of plastic raw materials is also high, and the development of alternative products with low energy consumption and low raw materials is also one of the market trends.

The blowing process of the bottle blowing machine is divided into two parts.

Preheat

The preform (preform) is irradiated by an infrared high-temperature lamp to heat and soften the body part of the preform. In order to maintain the shape of the bottle mouth, the preform mouth does not need to be heated, so a certain cooling device is required to cool it. .

Blow molding

In this stage, the preheated preform is placed in the blow mold that has been completed, and the interior is inflated with high pressure. Blow and pull the preform (embryo) into the required bottle.

The automatic bottle blowing machine combines the two operations of bottle blowing through the operation of the manipulator, eliminating the need for manual process of putting the preheated preform into the blowing mold. Greatly accelerate the rate of production.

The process flow of the bottle blowing machine

The blow molding process of the bottle blowing machine is a two-way stretching process. In this process, the PET chains are extended, oriented and arranged in two directions, thereby increasing the mechanical properties of the bottle wall and improving the tensile, tensile and impact strength. And has very good air tightness. Although stretching helps to increase the strength, it should not be overstretched. The ratio of stretch-inflation must be controlled: the radial direction should not exceed 3.5 to 4.2 times, and the axial direction should not exceed 2.8 to 3.1 times. The wall thickness of the preform should not exceed 4.3mm.

Bottle blowing is carried out between the glass transition temperature and the crystallization temperature, generally controlled between 90 and 110 degrees. In this interval, PET behaves in a highly elastic state, and becomes a transparent bottle after rapid blow molding and cooling and setting.

In the blow molding process, there are: stretching-blowing once-blowing twice. The three actions are very short, but they must be well coordinated, especially the first two steps determine the overall distribution of the material and the quality of the blown bottle. Therefore, it is necessary to set the parameters: stretching start timing, stretching speed, pre-blowing start and end time, 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 blow molding and cooling, induced stress is generated in the bottle wall. For gas-filled beverage bottles, it can resist internal pressure, which is good, but for hot-filled bottles, it is necessary to ensure that it is fully released above the glass transition temperature.