Blow molding machine screw is an important part of blowing machine.What are the main types of blow molding machine screw?The main types of screw extruder are common type, separation type and mixing type, and its structure and characteristics are as follows:
What are the main types of blow molding machine screw?
Blow molding machine screw 1: common type screw.
The common screw can be divided into three sections, namely, the feeding section, the gradient segment and the measuring section.The three sections are independent and not overlapping, characterized by long diameter ratio (L/D) for (20 ~ 30)/1;The length of the feeding section is (4 ~ 8)D, and the length of the measurement section is (6 ~ 10)D.Its function is to carry out solid conveying, melting, melt conveying, exhaust and mixing of raw materials.
Blow molding machine screw 2: separator screw.
The structure of the detached screw is roughly the same as that of the common screw, and the difference is that the segment is replaced by the separation segment.The length of the separation section is 5 ~ 15 times of the diameter of the screw.In the separation section, there is a barrier (also known as the secondary screw) in the spiral groove, which is larger than the main screw gap.In the design, the melt can be smoothed through the secondary screw, and the large size solid particles can be prevented from crossing the secondary screw.Adopt this time spiral rib can effectively separate the plastic melt and solid, the formation of two adjacent screw groove, plastic solid in the direction of the spiral groove slot section gradually become smaller, and melt slot section gradually become larger, achieve separation period ends, solid groove disappear, melt trough accounts for the whole of the spiral groove.
Its function is to separate the plastic solid from the melt, which is conducive to stabilize the solid bed and reduce or eliminate the damage degree of the solid bed.And can make the plastic melt completely or most through the groove edge.This makes the plastic melt more symmetrical and stronger, making the plastic melt more fluid.
Blow molding machine screw 3: mixing screw.
The mixing process of mixing screw plastic can be divided into distributed mixing and dispersed mixing.Distributed mixing means that the fluid will not be subjected to yield stress, but only increase the spatial distribution of each component, which is the mixing of the size of the components.The dispersion type mixing is the process of mixing the melt to yield the yield stress, and the material or gel material can be crushed to a critical size and distributed to the mixture.In the process of plastic processing, the dispersive mixing process is always accompanied by distribution mixing, but the distributed mixing process is seldom accompanied by dispersive mixing.