The Structure Principle of Dual Screw Extruder

The dual-screw extruder barrel is an important part of the extruder in the extrusion compression molding system. The barrel of the dual-screw extruder cooperates with the screw, the barrel accommodates the screw, and the screw rotates in the barrel.


When the screw rotates and pushes the plastic to move forward in the barrel, the external heating of the dual-screw extruder barrel conducts heat to the plastic in the barrel, and the volume of the thread on the screw gradually shrinks, so that the plastic in the thread groove is squeezed. It is uniformly mixed under the action of various forces such as pressing, turning and shearing.


Ⅰ. The structure of the hopper for feeding the dual-screw extruder barrel:


1. Vibrating hopper: its structure is relatively simple, just add an electromagnetic vibrator to the ordinary hopper. When the material needs to be fed into the barrel of the dual-screw extruder, start the vibrator to shake the hopper in the horizontal direction, then the raw material in the hopper overcomes the frictional resistance between the hopper wall and the material and slides down in the shaking together. And into the double screw extruder barrel.


2. Ordinary hopper: The hopper with simple structure and low cost is mostly used in small dual-screw extruders to feed the barrel. The feeding method of this hopper is to rely on the weight of the pellets to fall freely into the barrel.


3. Forced hopper: The feeding is mostly used in large dual-screw extruders or when the extrusion raw material is powder. The screw is driven to rotate by the motor after being decelerated by the worm gear, and a spring at the upper end applies a certain pressure to the screw, so that the raw material is pressed into the barrel when the screw rotates.


When the material in the barrel of the dual-screw extruder is full, the back pressure of the pressed material pushes up the screw and stops the barrel feeding. When there is no raw material in the barrel, the screw is pressed down by the spring force and continues to rotate to feed the barrel.


Ⅱ. Dual-screw extruder barrel requirements:


Made of corrosion- resistant and wear-resistant alloy steel. The blank should be formed by forging; the barrel of the dual-screw extruder should be quenched and tempered after rough machining; after machining, the wall thickness should be uniform, and the machining accuracy of the inner hole should meet the standard; the roughness of the inner hole surface after finishing should not be too large; The surface of the inner hole should be nitrided, and the depth of the nitrided layer should be within the range.


KY is currently the largest manufacturer of parallel co-rotating dual-screw extruders in China and even in Asia, with an annual output of 250-450 units. More than 8,000 extruder systems have been installed worldwide, covering the chemical, plastics, textile, food and pharmaceutical industries. If necessary, welcome to consult.

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