According to the rotation direction of the twin screw extruder can be divided into two kinds of extruder: the same direction and the different direction. Co-direction extruder means that the two screws rotate in the same direction when they work, while heterodirection extruder means that the two screws rotate in opposite directions when they work.
According to whether the axis line of the twin screw is parallel or not, it can be divided into two kinds of extruder with parallel axis line and intersecting axis line. Parallel twin-screw extruder with parallel axis lines, conical twin-screw extruder with intersecting axis lines. Twin screw extruder and meshing and non meshing points.
The difference between parallel and conical twin screw barrel
The diameter of the parallel twin screw is the same, the diameter of the small end of the conical twin screw is different from the diameter of the big end;
The concentric distance
Twin screw center distance is the same, the two axis of the conical twin screw Angle, the size of the center distance changes along the axis;
The draw ratio
Parallel twin screw (L/D) refers to the effective part of the screw length and the ratio of the outer circle of the screw, conical twin screw (L/D) refers to the effective part of the screw length and the ratio of the average diameter of the big end and the small end.
The most significant difference between parallel and conical twin screw extruders is the different geometry of the screw barrel, which leads to many differences in structure and performance. Although the two extruders have different characteristics, they have their own advantages.
The advantages of conical Twin Screw Barrel
Conical twin screw extruder two conical screw horizontal arrangement, two axis is a included Angle into the barrel, the center distance of the two axes from the small end to the big end gradually becomes larger, so that the transmission gearbox two output shaft has a larger center distance, the gear and gear shaft in the transmission system and the radial bearing and thrust bearing supporting these gear shafts have a larger installation space, It can be equipped with larger specifications of radial bearings and thrust bearings, each drive shaft has enough to meet the transmission torsion diameter, so large torsion, large load bearing capacity is a major feature of conical twin screw extruder. This parallel twin-screw extruder is incomparable.
When the double screw extruder is working, the melt in the screw head will produce very large pressure (head pressure), the pressure is usually about 14MPA, sometimes even up to more than 30MPA, this pressure on the screw to form a strong axial thrust, thrust is the role of the bearing.
Conical twin screw extruder for the arrangement of two screw Angle, so the transmission gearbox output shaft have two larger center distance, gear in the gear box before and after the two staggered larger thrust self-aligning ball bearings, enough to stop by the axial force formed by the pressure of the nose, the characteristics of bearing capacity is big, the gearbox manufacturing cost is low, maintenance is convenient.
How to choose a suitable twin screw extruder?
For users, the choice of twin screw extruder is very important. Different types of twin screw extruder have different performance and application occasions. Therefore, it is necessary to make clear the performance and application occasions of various twin screw extruder. For example, the meshing type co-rotating twin screw extruder because of its high speed, high shear rate, combined screw, it is widely used in the modification of non-thermal decomposition polymer ---- blending, filling, fiber reinforcement and material reaction extrusion.
For example, meshing type different rotating twin screw extruder, because of its good mixing plasticizing function, its biggest characteristic is PVC powder direct molding processing. Such as changing the geometric structure of the screw, can also be used for other materials forming processing, but its strength is still PVC forming processing.
According to the size of the plastic section, determine the amount of extrusion, and then by the amount of extrusion to choose the specifications of the twin screw extruder. In the plastic processing and molding process conditions are basically the same, conical twin screw extrusion machine to adapt to larger head pressure, parallel twin screw extrusion machine to adapt to smaller head pressure.
Lianzhong Industry Co., Limited is one of the biggest manufacturers of bimetallic screw&barrel and twin screw&barrel in China. The occupied area is more than 14000 m2. Integration of “Science and technology, production, sales”, introducing into the high and new technology, w dedicate to research and develop Cobalt-based Tungsten carbide super hard bimetallic screw and barrel with high wearing resistance, high corrosion resistance, high hardness which lies in the top place in the world now.
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Lianzhong Industry Co.,Limited is one of the biggest supplier of bimetallic screw&barrel and twin screw&barrel in China. The occupied area is more than 14000 ㎡. Integration of “Science and technology, production, sales”, introducing into the high and new technology, w dedicate to research and develop Cobalt-based Tungsten carbide super hard bimetallic screw and barrel with high wearing resistance, high corrosion resistance, high hardness which lies in the top place in the world now.