The transmission part is usually composed of a motor, a reduction box and a bearing. During the extrusion process, the screw speed must be stable and cannot change with the change of the screw load, so as to maintain the uniform quality of the products obtained. However, in different occasions, the screw must be variable speed to achieve the requirement that one piece of 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. On the premise that the structure is basically the same, the manufacturing cost of the reducer is roughly proportional to its outer size and weight. Because of the large shape and weight of the reducer, 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 high-efficiency extruders consume more energy than conventional extruders. The power of the motor is doubled, and it is necessary to increase the frame size of the reducer accordingly. But a high screw speed means a low reduction ratio. In the same size reducer, the gear modulus of the low reduction ratio is increased compared with the large reduction ratio, and the load bearing capacity of the reducer is also increased. Therefore, the increase in volume and weight of the reducer is not linearly proportional to the increase in motor power. If the amount of extrusion is used as the denominator and divided by the weight of the reducer, the number of high-speed and high-efficiency extruders is smaller, and the number of ordinary extruders is larger. In terms of unit output, the low motor power of the high-speed and high-efficiency extruder and the small weight of the reducer mean that the manufacturing cost of the unit output of the high-speed and high-efficiency extruder is lower than that of the ordinary extruder.