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Extruder is an important processing equipment whose application can be seen in plastics, rubber, fibers, among others in modern industrial production. Along with day-to-day increase in fierce competition in the market, the policy for environmental protection enhanced unceasingly, so urgent it becomes as to how to improve the production effectiveness of the extruders so as to save energy and improve the product quality. It provides a new solution to drive for the reconstruction of an extruder using a permanent magnet synchronous motor .
Operating Principle and Characteristics of Permanent Magnet Synchronous Motors
Permanent magnet synchronous motors are one class of motors that, by using permanent magnets to generate a magnetic field, their working principle and characteristics are different from traditional asynchronous motors. The operating principle mainly consists of the interaction between the magnetic field generated and the electric current. Rotation occurs due to a resultant magnetic force when there is a permanent magnet in a magnetic field. Simultaneously, a magnetic field will be developed within itself by the stator winding, which is due to a flow of current within its windings and couple the magnetic field of a given permanent magnet and hence allow continuously rotating it. The permanent magnet synchronous motor rotor is excited by a magnetic field created by permanent magnets; hence, no excitation current is used, reducing energy loss and increasing the efficiency.
Compared to asynchronous motors, permanent magnet synchronous motors have their merits and features, such as the following.
High efficiency
The efficiency of permanent magnet synchronous motors is very high, usually more than 10% higher than asynchronous motors. This is due to the fact that the rotor of a permanent magnet synchronous motor is driven by a magnetic field generated by permanent magnets, which does not require an excitation current, thus reducing energy losses. In addition, the control system of permanent magnet synchronous motors is more advanced, and precise control of the motor can be achieved through vector control technology, further improving efficiency.
High torque density
Permanent magnet synchronous motors are usually very efficient, more than 10% higher compared with asynchronous motors. It is so because in a permanent magnet synchronous motor, its rotor is excited by a magnetic field created by a permanent magnet and does not require an excitation current. Therefore, this may help reduce the losses of energy. Furthermore, because of a very developed control system in PMSM, through vector control technology, it is highly precise and efficient. High torque density
Permanent magnet synchronous motors have higher torque density compared to asynchronous motors. This is attributed to the fact that permanent magnets are of higher magnetic field strength, thus can develop greater torque. Thus, permanent magnet synchronous motors can easily meet heavy-duty applications such as extruders.
Precise control
Permanent magnet synchronous motors have more developed controlling systems capable of precisely controlling the motor using vector control technology. This provides precision control on speed, torque, current, among other parameters, thus meeting the particular requirements of extruders and any other machinery for their driving motors.
High Reliability
The permanent magnet synchronous motor structure is relatively simple; it reduces mechanical friction and wear, improving the reliability of the motor. Besides, since a permanent-magnet synchronous motor’s controlling system is more advanced, the chances of malfunction can be reduced, further improving reliability.
Low Noise
Permanent magnet synchronous motors have no noise, improving quality and reducing noise pollution within the production environment due to the simple structure of a permanent magnet synchronous motor, running stably with reduced mechanical friction and vibration.
Extruder working principle and requirements
The extruder is one kind of mechanical equipment that, through extruding and plasticizing materials, makes them into continuous profiles with certain shapes and sizes. Its working principle is mainly based on the rotation of the screw and friction between screw and barrel. The materials would be pushed to the front end of the barrel at this time, creating a certain density of the material mass. When the material mass reaches the front end of the barrel, the material starts its melting and compressing into high-density melt as the pressure and temperature increase. Later, the melt goes through the head and out of the mouth mold and extrudes into a continuous profile with the desired shape and size.
An appropriate drive motor is important for the normal running of the extruder and improving production efficiency.
In order for the effect of the extruder to be good, there is a requirement for the driving motor in place including stable material transportation.
Stable material transportation
The same reason extruders want material conveying that is stable-material flow and stability of the production process. Hence, what is expected from the drive motor is to provide stable torque and speed to ensure stable rotation of the screw.
Precise temperature control
Extruders have been designed to work under very specific temperature conditions for ensuring uniform plasticization and melting. For this reason, the driving motor should have provision for proper temperature control so that the temperature of the barrel and screw could be maintained within a specified range.
Precise flow control
The extruders must make a profile of consistent size and form; therefore, precision flow control is necessary. The functions for this must, therefore, be precision-flow-controlled in the drive motor so that accurate regulation of material flow is realized.
Energy efficient
Efficiency in the energy performance of the extruder leads to a cut in production costs while productivity is also improved. Motors driving shall thus be energy efficient to improve upon energy usage and enhance effectiveness of production.
Application of permanent magnet synchronous motor in extruder
As an effective energy-saving driving device, PMSM finds its broad applications in the drive system of the extruder. The permanent magnet synchronous motor connects to the screw of the extruder for its effective and stable working and highly precise rotation. In this respect, a control system of the permanent magnet synchronous motor will be enabled to manage precisely in real accordance with the demands of extruding in the name of high accuracy of flow of material and temperature.
In addition, the permanent magnet synchronous motor mounted in the extruder can meet the purpose of energy saving and consumption reduction. Permanent magnet synchronous motors have much higher efficiency, with much lower energy consumption compared to asynchronous ones. Control of the permanent magnet synchronous motor will also be precisely set according to the actual demand of the equipment, which further reduces energy waste. In addition, the permanent magnet synchronous motor structure is simple and easy to maintain, which can reduce the mechanical wear and failure to extend the service life of the equipment.
Permanent magnet synchronous motor applied to extruder effect is very significant, following:
Improve production efficiency
Permanent magnet synchronous motors have higher efficiency and lower energy consumption, which can reduce energy consumption and further improve production efficiency. In the meantime, for permanent magnet synchronous motors, their control system can be precisely controlled according to actual demands, further reducing material wastes and improving production efficiency.
Improve product quality
With permanent magnet synchronous motors in extruders, it can also be observed that the product quality will be improved. This is because, in the case of a permanent magnet synchronous motor, the operating control system will be able to precisely regulate the flow and temperature of the material, which reduces unevenness and defects of the material and improves product quality. Meanwhile, the simple structure and easy maintenance of the permanent magnet synchronous motor will reduce the mechanical wear and failure, further ensuring the quality of the product.
Extend the service life of the equipment
The service life could be extended when using an extruder with a permanent magnet synchronous motor. This is because of the permanent magnet synchronous motor, which is of simple structure and easily maintained. This reduces the mechanical wear and failure, hence prolonging the service life of equipment. In the meantime, the permanent magnet synchronous motor is able to control the control system precisely according to the practical needs, which may reduce superfluous waste and wear in machinery, prolonging its lifetime.
The field of plastic extruders would have been a much promising development potential with improving technological advancements and variations in market demand. Along with the increase in environmental protection awareness, the restriction in energy consumption will be an inevitable development trend that cannot be avoided in the extrusion industry. Permanent magnet synchronous motor, as a kind of highly efficient and energy-saving driving equipment, will receive more attention and importance. Continuous intelligent and automation technology development will make the extruder control system smarter and more automated. Permanent magnet synchronous motor control systems are of high intelligence, capable of high precision in speed and position control, and meeting the special requirements that extruders put on drive motors. Besides, with the manufacturing process improved and innovated step by step, the efficiency and performance of extruders will be further improved. Permanent magnet synchronous motors will be more and more applied in extruders because of their simple structure and easy maintenance. In a word, permanent magnet synchronous motors have great advantages and prospects in the field of extruders. Later, with the continuous development and changes in technology and market demand, permanent magnet synchronous motors will contribute more and more to the field of extruders for a more important guiding role of technicians in related fields. We believe that permanent magnet synchronous motor driving technology will be one of the core driving technologies for the near-future development of extruders and will contribute to the promotion of extruder industry development.
