Research on domestic linear motors
Although there are many units for linear motor research in China, there are mainly three universities that study linear motor as a machine tool or machining center feed system: Guangdong University of Technology has established "super high speed machining and machine tool research room", mainly research and development " Ultra-high speed electric spindle" and "linear motor high-speed feed unit". They studied the linear induction motor and developed the GD-3 linear motor high-speed CNC feed unit with a rated feed force of 2kN, a maximum feed rate of 100m/min, a positioning accuracy of 0.004mm and a stroke of 800mm. Since the late 1990s, Shenyang University of Technology has conducted research on permanent magnet linear synchronous motors and manufactured prototypes with a thrust of 100N. Another focus of their research is on the control of the motor and the servo system, and has published several papers on this. The Institute of Precision Engineering and Mechanical Engineering of Tsinghua University has successfully developed a high-frequency DC linear motor with a stroke of up to 5 mm, a cut-off frequency of more than 250 Hz, and a thrust of several hundred Newtons. It is used to drive a transverse knives for a medium-convex piston lathe. The frame has achieved good application results in actual processing. The long-stroke permanent magnet linear servo unit is currently under study. The rated thrust of the motor is 1500N, the maximum speed is 60m/min, the maximum acceleration of no-load is 1g, and the stroke is 600mm.
It should be noted that in China, the research on linear motor, especially the linear servo motor in the machine tool feeding system, is still in its infancy. The researchers and funds are obviously insufficient, the progress is slow, and the gap with foreign countries is getting bigger and bigger. It is already imminent. In order to break the foreign technology monopoly, we must take the road of combining technology tracking and independent development, and strengthen the research of basic and key technologies.
5 Development trends and research directions
development trend
At present, the development of linear motor direct drive technology presents the following trends:
The linear servo motor for the machine feed system will be dominated by permanent magnets:
Integrate motors, encoders, rails, cables, etc. to reduce motor size for easy installation and use:
Modularize the various functional components (rails, encoders, bearings, connectors, etc.):
Focus on the development of related technologies, such as position feedback components, control technology, etc., which is the basis for improving the performance of linear motors.
research direction
The research goal of linear motors is to improve the performance of the motor and meet the application requirements. The main properties of linear motors include speed, acceleration, thrust and its fluctuations, positioning accuracy, repeat positioning accuracy, mechanical properties (speed-thrust characteristics), transient performance (speed response) and thermal characteristics.
As an electromechanical system, to improve performance can be achieved from both structural and control aspects.
Structural design
Linear motors include primary and secondary magnetic circuit structures as well as mechanical structures such as support, sensing measurement, cooling, dust protection, and protection.
Magnetic circuit design
The most important task of magnetic circuit design is to make the thrust and thrust fluctuations of the motor meet the design requirements.
The calculation of the magnetic field distribution in the motor is the basis of the magnetic circuit design. Due to the particularity of the structure, the linear motor has an end effect, causing distortion of the magnetic field, and a soft magnetic material such as a silicon steel sheet is used to aggregate the magnetic circuit. The boundary of the medium is zigzag, the magnetic circuit is complex, and the nonlinearity is strong. If the calculation is carried out by the traditional equivalent magnetic circuit method or graphic method, a large error will occur, which is even impossible. Therefore, the numerical solution is generally used at present - mainly by using the finite element method (FEM) to calculate the magnetic field distribution of the linear motor, thereby further calculating the thrust and its fluctuation and the vertical force. At present, there are many excellent electromagnetic field FEM software available on the market, so the key point of using FEM to calculate the electromagnetic field of linear motors is to establish an accurate finite element model.
Reducing thrust fluctuations is a key and difficult point in magnetic circuit design. Thrust fluctuations are caused by high-order harmonics of primary current and back electromotive force, non-sinusoidal air gap waveform, cogging effect, and end effect. Thrust fluctuations can be reduced by optimizing the shape and arrangement of the permanent magnets, reducing the permanent magnet excitation magnetic density, using a coreless and multi-pole structure, increasing the number of slots, and adding air gaps, but some measures can cause other performance. The weakening, so design should consider the design requirements to achieve the best results.
There are many problems involved in the mechanical structure design of the mechanical structure. Here we only emphasize the study of the cooling system, because this problem is easily overlooked. In fact, thermal characteristics are an important characteristic of linear motors. The same type of motor has twice the thrust peak when cooling, so the motor cooling system has a great influence on the performance of the motor. Start with the cooling system. Optimizing the design is a shortcut to improve motor performance. The analysis of the thermal characteristics of the motor is also generally based on the finite element method, and the cooling is optimized based on the calculation results.
Previous page next page
Socket Head Cap Screws,Hexagon Socket Head Cap Screw,Hexagon Socket Round Head Screw,Phillips Hex Head Screw
we enhanced the hardness of the screws by heat treatment which can efficiently prevent slip and break. With a stable and reliable quality, Lanejoy screws will be your best choice.
China Socket Head Cap Screws,Hexagon Socket Head Cap Screw,Hexagon Socket Round Head Screw,Phillips Hex Head Screw, we offered that you can trust. Welcome to do business with us.
Machine screw,tapping screw,self drilling screw,flat head screw,Pan head screw
Shenzhen Lanejoy Technology Co.,LTD , http://www.grill-grid.com