Screw of large plastic blow molding machine is an important part of the production process.
When the blow molding machine is working, the screw can uniformly plasticize the raw materials into a molten state during the rotation. Extrude to the die to form the required blanks for mold forming.
Simply put, the main function of the blow molding machine screw is to plasticize, melt, and convey the raw materials for blow molding.
What Yankang wants to popularize with everyone today is the types of the screw of large plastic blow molding machine.
The ordinary screw is mainly divided into three sections: feeding section, gradual change section, and metering section.
The three paragraphs are independent and non-overlapping. The aspect ratio of each section is different.
The basic function is to transport, melt, transport, exhaust, and mix raw materials.
The structure of the separation type screw and the ordinary type screw are similar. The difference is that the separation type screw uses a separation section instead of the gradual change section of the ordinary type screw.
The main feature is that there are two main and auxiliary threads in the melting section of the screw and form two screw grooves.
One of the grooves is filled with solids and the other groove is filled with liquids.
The melt film formed in the solid screw barrel is transported into the liquid screw through the high-speed and stable rotation of the screw.
The liquid passes through the homogenization section of the screw, and the length of the homogenization section is increased accordingly.
The melt-processed by the screw of this type of blow molding machine is relatively stable, the plastic melt rheology is better, and the use performance is relatively high.
The main feature of the barrier screw is that an extra barrier section is added at a certain position of the screw. The purpose is to better improve the mixing capacity.
The longitudinal grooves opened in the barrier section are divided into two groups, one group is a feed slot with a closed outlet; the other group is a feed slot with the closed inlet. All melted materials or unplasticized plastic particles are forced to pass through the barrier section. The gap of the barrier section is small, the shear rate is large, and the shearing effect is strong. Plastic particles can quickly plasticize and can further mix the melt.
The main feature of the split screw is to add pins or split blocks at a certain position of the screw, the purpose is to increase the screw’s mixing capacity for raw materials.
Pins or shunt blocks play different roles in different positions. The mixing and stirring effect of raw materials can be improved in the screw homogenization section. Increase the shear rate in the melting section.
Although the effect of pins or shunt blocks is not so significant, they are generally good for improving the mixing effect of materials.
CTM (Cavity Transfer Mixer) screw
It consists of a stator and a rotor. The stator is a part of the screw barrel, and the rotor is a cylindrical screw with a smooth head.
Several spherical holes are regularly distributed on the stator and rotor, forming a section of the CTM screw structure.
CTM screw is a kind of screw with relatively high mixing efficiency. At the same time, the feeding section of the screw is cooled by water, which can provide enough melt.
The mixing screw is the mixing in the plastic processing process and can be divided into distributed mixing and dispersing mixing.
Distributed mixing can prevent the fluid from showing yield stress and better ensure the quality of the fluid.
Dispersive mixing is a mixing process that can make the melt exhibit yield stress.
In the plastic processing process, the dispersive mixing process will be accompanied by distributed mixing. However, the distributed mixing process is almost not accompanied by dispersive mixing.
Because large plastic blow molding machines are equipment used to produce large plastic products, they need to process a large number of raw materials and large preforms, so the performance requirements of the screw are relatively high.
The screw of a large plastic blow molding machine generally needs to have the characteristics of strong plasticizing ability, uniform mixing and stirring effect, and stable temperature.
The large plastic blow molding machine equipment produced by the Yankang blow molding machine manufacturer adopts IKV screw, which has a strong plasticizing ability and stable extrusion performance. The head pressure hardly affects the production efficiency of the equipment, and the fluctuation is small.
At the same time, compared with the traditional screw, the IKV screw has higher production efficiency and energy saving, which can greatly save the cost of raw material consumption; while saving energy, the plasticizing capacity is 1.5 times that of the traditional screw.
That’s it for the introduction of screw types for large plastic blow molding machines.
It is very necessary to choose a screw with stable performance for the plastic blow molding machine.
Especially for large plastic blow molding machines, the processing capacity of raw materials is greater, and the stable screw can greatly improve the processing effect of raw materials, ensure the quality of raw materials, and lay a good material foundation for the production of plastic blow molding products with stable quality.