Screw presses is an important part of blow molding machine. What are the main types of the screw of the blow molding machine?
The main types of the blow molding machine screw are three kinds of common type, separation type and mixing type. The structure and characteristics are as follows:
What are the main types of the screw of the blow molding machine?
Screw 1 of blow molding machine: common type screw
The structure of the common screw can be divided into three sections, that is, the feeding section, the gradual change section and the measuring section. The three segments are independent and do not overlap each other. The length and diameter ratio (L/D) is (20~30) /1, the length of the feeding section is (4~8) D, and the length of the metering section is (6~10) D. Its role is to carry out solid material transportation, melting, melt transportation, exhaust and mixing.
Blow molding machine screw two: separate screw
The separation type screw structure is the same as that of the ordinary screw. The difference is that the separation section is replaced by the separation section. The length of the separation section is 5~15 times the diameter of the screw. In the separation section, there is a barrier edge (also known as the secondary spiral) in the slot, which is larger than the gap between the main screw and the wall. In the design, the melt can pass through the snail prism smoothly, and it can prevent the large size solid particles from crossing the snail prism. By this time the screw can effectively separate the plastic melt and solid, the formation of two adjacent screw groove, along the direction of spiral groove plastic solid groove section and gradually become smaller, and the melt groove section gradually increased, reached the end of separation, solid groove disappear, melt channel accounted for the entire channel.
Its function is to separate plastic solid from melt, which will help stabilize the solid bed, reduce or eliminate the destruction degree of the solid bed, and make the plastic melt wholly or most pass the secondary groove edge. This makes the plastic melt more symmetrical and more intense, so that the rheological property of the plastic melt is better.
Blow molding machine screw three: mixing screw
Mixing type screw plastics can be divided into distributed mixing and dispersive mixing in the process of mixing. The distribution type mixing means that the fluid does not present the yield stress, but only increases the spatial distribution between the components, and is the mixing of the size of the component that does not change. Dispersion mixing is a mixing process that enables the melt to yield stress. It can be crushed into a critical size and distributed into the mixture. In the process of plastic processing, the distributed mixing process is always accompanied by distributed mixing, but almost no mixing effect occurs in the distribution mixing process.