To understand how an automatic PET bottle blowing machine operates, let's look at its workflow. The entire process relies on seven core systems working together to transform PET preforms into finished bottles.
The electronic control system acts as the brain for the bottle blowing molding production line. The PLC controller, various function sensors, and servo motors need to coordinate seamlessly. It commands the performs shifting, stretching cylinder movements, etc, to ensure orderly production.
The PET preforms are heated in the infrared segmented-heating zone via a feeding system, which includes a robotic arm and an adjustable-speed conveyor. The simple step is challenging, requiring PET preforms to be neatly and stably fed into the heating ovens. Any jamming or disruption in the queue will impact the entire process. The infrared heating system can adjust the temperature across different areas based on wall thickness, PET preform structure, and bottle shape, etc. It ensures the PET bottle preforms are heated evenly without causing local crystallization or deformation.
Once the preforms are softened, the crucial steps of the mold closing and stretching stage begin. It involves a three & four-platen clamping structure, coupled with a hyperbolic link for force amplification. Upon receiving a signal from the solenoid valve, the cylinder securely locks the mold. The stretching cylinder drives the stretching rod to longitudinally stretch the bottle blank. At the same time, the high-pressure air source is supplied during the product molding process, to expand laterally near the bottle mold inner surface - this is usually called "biaxial stretching". The step determines the bottle's initial shape. The preform is being formed while the high-pressure source is supplying. It primarily consists of a high-pressure air tank, a proportional valve, and a sealing cylinder. Pressure control and hold time here require extreme precision. I've seen numerous cases of bottles with uneven thicknesses caused by unstable air pressure, leading to the scrapping of entire batches -a regrettable outcome. During the bottle forming process, cooling efficiency determines the production speed of the blow molding line; circulating cooling water quickly cools the product. After the bottles are formed and demoulded, the mechanical arm smoothly removes them, places them on the conveyor belt, and then sends them to the storage area for packaging or connects the automatic bottle blowing machine to the filling line for direct filling.
The automatic PET bottle blowing machine is currently driven by servo motors. It enables the simultaneous operation of multiple stations and improves efficiency. The machine design focuses on longitudinal rigidity and long-term production stability, which can produce PET bottles of various specifications and is used in the beverage, daily chemical, etc.