Extrusion Blow Moulding Machine Process

The process flow of the extrusion blow moulding machine mainly includes the following steps:

1. Raw material preparation

First, it is necessary to select suitable plastic raw materials according to the characteristics of the required plastic products. Common ones include polyethylene (PE), polypropylene (PP), etc. These raw materials exist in granular form, and it is necessary to ensure that they are dry and free of impurities to avoid affecting the quality of the product. After the raw materials are poured into the extruder hopper, they enter the extruder screw area by gravity.

2. Extrusion plasticization

The plastic particles entering the extruder are transported forward along the screw groove of the screw under the rotation of the screw. The screw gradually melts and plasticizes the plastic raw materials through shearing, friction heat generation and the synergistic effect of the external heating device to form a uniform viscous fluid state. In this process, temperature control is very important. Different temperatures will be set for the screw sleeves in different areas to ensure that the plastic can be fully plasticized without decomposition. Generally speaking, the temperature is slightly lower near the hopper end and slightly higher near the head end.

3. Head molding

The plasticized plastic melt is continuously pushed to the head mold part by the screw. The die head mold has a specific cavity structure, which enables the plastic melt to form a tubular parison around the core rod. The wall thickness and diameter of the parison can be precisely controlled by the adjustment device of the die head to meet the requirements of different product specifications.

4. Blow molding

When the parison reaches the predetermined length, the mold closes quickly and clamps the parison between the two halves of the mold. At the same time, the blow pipe is inserted into one end of the parison, and compressed air is introduced into the parison, so that the parison is close to the inner wall of the mold under the action of air pressure, thereby inflating and forming, and obtaining the desired shape of the plastic product. The blowing pressure, time and blowing volume need to be finely adjusted according to factors such as product size and plastic material.

5. Cooling and shaping

The plastic products after blow molding are still in a plastic state due to the high temperature, and need to be cooled to shape them. The mold is usually designed with a cooling water channel, and the circulating cold water takes away the heat of the plastic product, prompting it to solidify quickly. The cooling time should be set reasonably. Too short may cause product deformation, and too long will reduce production efficiency.

6. Demolding

After sufficient cooling and shaping, the mold is opened, and the molded plastic product is removed from the mold with the help of a demoulding mechanism (such as ejector pins, demoulding cylinders, etc.), completing a complete extrusion blow molding cycle. Subsequently, the product enters the subsequent processing steps or packaging links, and the extrusion blow moulding machine is ready to enter the next round of production process.

The process flow of the blow moulding machine is closely linked, and each step needs to be precisely controlled to stably and efficiently produce high-quality plastic products.