Blow Molding Machine 4-Way Valve Group

High-Pressure Blow Molding Valve Group with Recovery

Professionally designed for economical and fast bottle blowing production; more efficient and energy-saving than blow molding machines equipped with high-pressure solenoid valves.

Uses proven and reliable valve technology, adopting low-power, direct-acting customized pilot solenoid valves, with simple maintenance and repair.

P1: Pre-blow

P2: Main blow

REC: Recovery

EXH: Exhaust

Pilot air pressure: 7 bar + 0 / -0.5 bar

Working pressure: 4 ~ 40 bar

The blow molding blowing process is a stretching process. The equipment stretches the relevant material bidirectionally along this process—orienting and arranging it—thereby improving the mechanical properties of the bottle wall, enhancing tensile, stretch, and impact strength, and providing good air tightness. Although the intake port of the air source triplet can improve strength, it must not be too large; the stretching and blowing ratios must be controlled: diameter must not exceed 3.5~4.2, and axial must not exceed 2.8~3.1. The bottle wall thickness must not exceed 4.5 mm.

The blowing process takes place between the glass transition and crystallization temperatures, generally controlled at 90–120°C. During this period, PET exhibits high elasticity; rapid blow molding and cooling solidification form a transparent glass bottle.

The blow molding process is divided into three steps: stretch – first blow – second blow. The duration of each step is very short, but they must be well coordinated, especially the first two steps, which determine the distribution and quality of the entire bottle. Therefore, the air filter combination triplet (FRL unit) must be properly adjusted: stretch start timing, stretch speed, pre-blow start, blow-out timing, blow-out duration, blow duration, blow speed, etc., to control the temperature distribution of the entire bottle body and the temperature difference between the inner and outer walls of the bottle.

Conclusion: The preform is conveyed from the automatic loader to the main unit of the blow molding machine, transported via conveyor belt to the preheating oven, then to the mold clamping device, where it is stretched by the tie rod, pre-blown, and high-pressure blown into a finished bottle—requiring no manual intervention, fully accomplished by the blow molding machine. It offers a high degree of automation, saving labor and cost, and increasing overall economic efficiency.