"Asia Rubber Expo & India Rubber Technology Exhibition 2020" is jointly sponsored by Aakar Exhibition Company and Zhonglian Rubber Co., Ltd. The exhibition will be held at the Chennai Trade Center...Read More
1. Classification of extruders
Plastic extruders are divided into single-screw, twin-screw and multi-screw extruders according to the number of screws. At present, single-screw extruders are widely used and are suitable for extrusion processing of general materials. The single-screw extruder occupies an important position both as a plasticizing and granulating machine or a molding and processing machine. The main sign of its development lies in the development of its key component, the screw. So far, there are nearly 100 kinds of screws and they have been standardized. Common types are separation type, shear type, barrier type, split type and wave type. From the perspective of the development of single screw, although single screw extruder has been relatively perfect in recent years, in general, single screw extruder is developing in the direction of high speed and specialization.
2. Composition of screw extruder
The plastic extruder is mainly composed of the main machine, the auxiliary machine of the extrusion unit and the control system.
(1) The main engine of the extruder is composed of an extrusion system, a transmission system and a heating and cooling system. The extrusion system includes screw, barrel, hopper, die and die. The plastic is plasticized into a homogeneous melt through the extrusion system, and is continuously extruded by the screw under the pressure established in the process; the function of the transmission system is to drive the screw to provide the torque and Rotating speed. It usually consists of a motor, a reducer and a bearing; heating and cooling are necessary conditions for the plastic extrusion process to proceed.
(2) The auxiliary machines of the extrusion unit mainly include a pay-off device, a straightening device, a traction device, a cooling device, a preheating device, a wire take-up device, a meter counter, and a spark tester. The purpose of the extrusion unit is different, and the auxiliary equipment used is also different.
(3) The control system of the extruder includes a heating system, a cooling system and a process parameter measurement system, mainly composed of electrical appliances, instruments and actuators. Its main function is to control and adjust the driving motor of the main and auxiliary machines, output the speed and power that meets the process requirements, and enable the main and auxiliary machines to work in harmony; detect and adjust the temperature, pressure, and flow of the plastic in the extruder; Control or automatic control of the entire unit.