Extruder composition

Among extruders, in general, the most basic and versatile one is the single-screw extruder. It mainly includes six parts: transmission, feeding device, barrel, screw, machine head and die.
Transmission part
The transmission part usually consists of motor, reduction gearbox and bearings. During the extrusion process, the screw speed must be stable and cannot change with changes in screw load, so as to maintain uniform quality of the resulting product. However, under different circumstances, it is required that the screw speed can be changed to meet the requirements that one equipment can extrude different plastics or different products. Therefore, this part generally uses AC commutator motors, DC motors and other devices to achieve stepless speed change. Generally, the screw speed is 10~100 rpm.
The function of the transmission system is to drive the screw and supply the torque and speed required by the screw during the extrusion process. It is usually composed of a motor, a reducer and a bearing. Under the premise that the structure is basically the same, the manufacturing cost of the reducer is roughly proportional to its overall size and weight. Because the shape and weight of the reducer are large, it means that a lot of materials are consumed during manufacturing, and the bearings used are also relatively large, which increases the manufacturing cost.
For extruders with the same screw diameter, high-speed and efficient extruders consume more energy than conventional extruders. It is necessary to double the motor power and increase the frame size of the reducer accordingly. But high screw speed means low reduction ratio. For reducers of the same size, the gear module with a low reduction ratio is larger than that with a large reduction ratio, and the load-bearing capacity of the reducer is also increased. Therefore, the increase in the volume and weight of the reducer is not linearly proportional to the increase in motor power. If you use the extrusion volume as the denominator and divide it by the weight of the reducer, the number will be smaller for a high-speed and efficient extruder and larger for an ordinary extruder. In terms of unit output, the motor power of a high-speed and high-efficiency extruder is small and the weight of the reducer is small, which means that the machine manufacturing cost per unit output of a high-speed and high-efficiency extruder is lower than that of an ordinary extruder.