Important parameters of the homogenizing section screw

According to the theory of melt conveying, the flow of melt in the screw homogenization section has four forms, and the flow of molten material in the screw groove is a combination of these four flows: Positive flow-the flow of the plastic melt between the barrel and the screw along the direction of the screw groove towards the head.

Main parameters of screw in melting section

Compression ratio ε : Generally refers to the geometric compression ratio, which is the ratio of the volume of the first screw groove in the feeding section to the volume of the last screw groove in the homogenizing section. Epsilon = (Ds - H1) H1 / (Ds - H3) material H1 / H3

Main parameters of screw in feeding section

The helical elevation Angle ψ is usually 17° ~ 20°. The groove depth H1 is calculated by the geometric compression ratio ε of the screw after determining the groove depth in the homogenization section.

Segment of screw

When the material moves forward along the screw, it experiences changes in temperature, pressure, viscosity and so on. This change is not the same in the whole length of the screw. According to the changing characteristics of the material, the screw can be divided into adding (sending) material section, compression section and homogenizing section.

The screw of the extruder

The screw is the heart of the extruder, is the key component of the extruder, the performance of the screw is good or bad, determines the productivity of an extruder, the plasticizing quality, the dispersion of the additive, melt temperature, power consumption, etc. Extruder is the most important component, it can directly affect the application range and production efficiency of extruder. Through the rotation of the screw to produce extreme pressure on the plastic, the plastic can move, pressurize and obtain part of the heat from the friction in the barrel. The plastic can be mixed and plasticized in the process of moving in the barrel. When the viscous flow melt is extruded and flows through the die, the required shape is obtained and formed. Like the barrel, the screw is made of a high strength, heat and corrosion resistant alloy.

There are three forms of drum in structure

Advantages - easy to ensure high manufacturing accuracy and assembly accuracy, can simplify the assembly work, the cylinder heat evenly, more applications. Disadvantages - because the length of the barrel is large, the processing requirements are higher, and the requirements of the processing equipment are also very strict. The inside surface of the cylinder is difficult to repair after wear.