Application of Linear Motor in High Speed Machine Tool
time£º2017/6/27 click£º6275
With the rapid development of electronic technology, the application of linear motor in machine tool has ushered in its climax. From the 1996 American Chicago Machine Tool Exhibition IMTS '96, the 18th Japan Machine Tool Exhibition, to the 1999 Paris EMO Expo and a series of influential exhibitions, this indicates that the new era of linear motor development has arrived.
The high-speed processing developed to improve the efficiency of production and the quality of parts has now become a major trend in the development of machine tools. A responsive, high-speed and lightweight drive system, the speed must be increased to 40-50m/min or more, and the acceleration and deceleration must also be increased to 25-50m/s2. The traditional "rotating motor + roller screw" transmission form is obviously not good. This is determined by its own weakness, because the existence of the intermediate drive link initially reduces the stiffness, elastic deformation can increase the order of the system, and thus the robustness of the system is reduced and the servo performance is reduced. Elastic deformation is also the source of dynamic mechanical resonance of CNC machine tools. Secondly, the existence of the middle drive link increases the inertia of the moving body and slows the response of displacement and speed. In addition, factors such as gap dead zone, friction, error accumulation, etc., make the effective feed speed that this traditional method can achieve is 30m/min, and the acceleration is only 3m/s2.
The advantages of direct driving of linear motors can make up for the lack of traditional transmission methods, and its speed is 30 times that of roller rod pairs; The acceleration is 10 times that of the roller rod pair, effective up to 10g, and stiffness is increased by 7 times; In addition, the linear motor directly drives the worktable, so there is no reverse working dead zone; Due to the small amount of armature inertia, the linear servo system formed by it can achieve a higher frequency response(eg, 100Hz).
Through the above comparison, the application of linear motor has broad prospects in high-speed precision machining. At present, the main requirements for meeting the large thrust feed components of the machine tool are AC linear Motors, which can be divided into two types: permanent magnet(synchronous) and induction(asynchronous). The permanent magnetic secondary(stator) is magnetic steel. When applied to a machine tool, magnetic steel must be laid on the bed of the machine tool. In the lower part of the work table, a three-phase electric winding is installed to form the primary(moving) of a linear motor. The induction primary is the same as the permanent magnet, but its secondary is to replace the magnetic steel with a grid bar, which is equivalent to spreading the "rat cage" of the induction rotary motor along its circumference.
The permanent magnet linear motor is superior to the induction type in terms of thrust, power factor, controllability, etc., but the price is more expensive, and the installation, commissioning, and dust protection are not as good as the induction type.
The induction linear motor is close to the level of permanent magnet motor in performance, and its own advantages, so it is more and more popular.
In the field of high-speed processing, linear motors are widely used in high-speed milling machines, crankshaft lathes, ultra-precision lathes, grinders, laser lathes, etc.. The more popular research is to apply it to high-speed parallel mechanisms. That is, six-axis and three-axis parallel structure machine tools, through the expansion of multiple sliding plungers to control the tool, to achieve the high-speed processing of complex surface.
With the rapid development of high-speed machining technology, the requirements for transmission and control system are getting higher and higher, so that the research of linear motor driving technology is gradually increasing. Therefore, increasing the research on straight-line driving technology is not only the trend of higher and faster development of technology, but also better able to meet the needs of the market, bring more economic benefits, and become the trend of future development.
The linear motor produced by Kunshan tongmao electronics, using advanced technology standards, technology and testing methods in Europe and America, has achieved advanced quality and power performance, and can replace similar products from abroad. Welcome new and old customers to buy.
Linear motor