Semi-automatic bottle blowing machine is a kind of equipment used to make plastic bottles (usually PET bottles). Its working principle mainly involves the heating, stretching and blow molding of plastic raw materials. The following are the detailed working steps and principles:
(1) Heating (preheating): The preform is fed into an infrared heating furnace and heated evenly by infrared lamps. The heating temperature and time are very important. It is necessary to ensure that the preform reaches a temperature suitable for stretching and blow molding (usually 85-120°C) while avoiding local overheating and deformation. (2) Mold loading: The operator manually places the heated preform into the blow molding machine mold. The mold is usually a two-piece mold that can be closed to form the shape of the bottle. (3) Stretching and blow molding: After the preform is clamped, the stretch rod enters the preform from above and stretches the preform downward. The length of the preform is increased during the stretching process.
At the same time, the blow molding machine injects high-pressure gas (usually 6-12 bar) into the preform. Under the action of pressure, the preform expands along the inner wall of the mold until it is completely formed into the shape of the bottle. (4) Cooling and shaping: There is usually a cooling water circulation system in the mold to quickly cool the bottle and shape it. The cooling time depends on the bottle size, wall thickness and material properties.
