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The extruder originated in England in the 18th century, when the extruder was a manual extruder. With the emergence of large-scale power systems in the 20th century, electrically operated extruders quickly replaced the previous manual extruders. From now on, the power selection of the extruder is preferred to electric, and the electric motor has become the main power source and the main component of the extruder.
There are many types of motors used in the industry, and they are updated quickly. Therefore, in this era of rapid development of the plastics industry, the selection of the motor type of an extruder has become very important, which directly determines the performance and maintenance of the plastic extruder.
More than ten years ago, extruder manufacturers preferred to equip their equipment with DC motors, because DC motors have better speed regulation performance than the previous generation of step-less speed regulation motors.
But DC motors have two fatal disadvantages:
1. Adaptation of AC power grids. Nowadays, power networks in various countries all adopt the form of AC power grids;
2. The maintenance of large-scale DC motors is troublesome, and carbon brushes need to be replaced regularly.
At present, some companies at home and abroad have begun to use AC permanent magnet synchronous motors as the power source for extruders. The Chinese government is consciously promoting this type of AC permanent magnet synchronous motor. It is a good choice to choose an AC synchronous motor without considering the equipment procurement cost.
Although the cost of an AC synchronous motor is relatively high, it has some advantages compared with the conventional frequency conversion AC motor: 1. Under the same conditions, the energy consumption is about 8% lower;
2. The speed is more accurate, which is better than DC motors in this regard;
3. The motor has a large starting torque, which can achieve 2.5 times the starting torque;
4. The motor is small in size and easy to maintain (for example, when the power is 132kw and the center height of the extruder (base number) is required, the synchronous motor can be directly installed under the extruder screw, which can be effective Reduce the length of the extruder by about 2m. Make the structure of the extruder more compact and beautiful, while saving working space).
The last motor with the least use is a new type of multi-pole motor (permanent magnet direct drive motor). We all know that the more poles of the motor, the slower the maximum speed of the motor. This new type of motor is to control the speed of the motor below 100rpm by increasing the number of poles of the motor, and the motor manufacturer customizes the motor directly connected to the screw according to the size of the extruder screw and barrel flange. With this kind of multi-pole motor, the extruder will no longer need gearboxes, couplings, pulleys, and other devices, which greatly simplifies the structure of the plastic extruder and saves the maintenance of these parts, and also greatly reduces the equipment performance. It can save more than 30% of electrical energy than DC motors and 15% of electrical energy than AC asynchronous motors. It can also achieve step-less speed regulation to meet the requirements of different process products.
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