The co-rotating twin screw extruder has a high rotational speed and has a relatively close relative motion speed at different positions in the meshing zone, so it can produce strong and uniform shear.
The geometric shape determines that the longitudinal flow channel of the co-rotating dual screw extruder must be open so that material exchange occurs between the two screws. During the exchange, the material originally at the bottom of one screw groove will move to the top of the other screw groove. The opening of the longitudinal flow channel also makes it possible to open the transverse flow channel to realize the exchange of materials between adjacent grooves of the same screw.
Co-rotating twin screw has better distributive mixing ability, so it is suitable for mixing operation. The geometric parameters of the counter-rotating dual screw extruder determine that its longitudinal flow channel can be closed, so the material is forced forward by the screw, which is the so-called positive displacement.
This makes stable molding extrusion a key feature of a counter-rotating dual screw extruder. Therefore, when it comes to twin screws, the direction of rotation should be indicated.
From the perspective of the screw shape, the two screws rotating in the same direction are exactly the same, and the thread directions are the same. The two screws of the counter-rotating twin-screw extruder rotate in opposite directions, and there are two situations: inward rotation and outward rotation.
At present, there are few cases of inward rotation, because after the material is added from the feeding port, under the push of the two screws, the material will first enter between the radial gaps of the two screws in the meshing area, and form a material pile above. This reduces the free space of the screw groove that can be used, and ultimately affects the ability to receive materials from the feeder, which is not conducive to filling the screw groove as soon as possible and conveying the material forward. The feeding performance is not good, and it is easy to form bridges.
At the same time, the material entering the radial gap between the two screws has a force that separates the two screws and presses the screws to the barrel wall, thereby accelerating the wear of the screws and the barrel.
Outward rotation does not have the above-mentioned shortcomings. The material is quickly separated to both sides by the two screws, filling the screw groove, and quickly contacts with the hot barrel to absorb heat, which helps to heat and melt the material. In terms of appearance, the threads of the two counter-rotating screws are in opposite directions, one is right-handed and the other is left-handed, and the two are symmetrical.
Nanjing KY Chemical Machinery Co., Ltd. is currently the largest manufacturer of parallel co-rotating twin screw extruders in China and 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 you have any need, please feel free to consult us.
Tel: +86-25-52706155
E-mail: info@kymach.com
No.59 West Tianyuan Road, Jiangning, Nanjing, Jiangsu Province, China
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