Current Status of Linear Motors Applied on CNC Machine Tools
In recent years, the use of linear motors for CNC machine tools has become particularly popular. The reason is that high-speed and ultra-high-speed machining developed to improve production efficiency and improve the processing quality of parts has become a major trend in machine tool development. Sensitive, high-speed, lightweight drive system, the speed should be increased to 40 ~ 50m / min or more. The traditional "rotary motor + ball screw" transmission can achieve a maximum feed rate of 30m / min, acceleration is only 3m / s2. The linear motor drives the worktable, the speed is 30 times that of the traditional transmission mode, the acceleration is 10 times of the traditional transmission mode, the maximum is up to 10g; the stiffness is increased by 7 times; the table directly driven by the linear motor has no reverse working dead zone; Due to the small motor inertia, a linear servo system composed of it can achieve a high frequency response.
In 1993, ZxCell-O Company of Germany introduced the world's first HSC-240 high-speed machining center driven by linear motor. The maximum spindle speed of the machine tool reached 24000r/min, the maximum feed rate was 60n/min, and the acceleration reached 1g, when the feed speed is 20m/min, the contour accuracy can reach 0.004mm. Ingersoll of the United States immediately introduced the HVM-800 high-speed machining center with a maximum spindle speed of 20000 r/min and a maximum feed rate of 75.20 m/min.
Since 1996, Japan has successfully developed horizontal machining centers for linear motors, high-speed machine tools, ultra-high-speed small machining centers, ultra-precision mirror machines, and high-speed forming machines. Zhejiang University of China has developed a punching machine driven by a linear motor. The Institute of Production Engineering of Zhejiang University has designed a parallel mechanism coordinate measuring machine driven by a cylindrical linear motor [2]. In 2001, Nanjing Sikai Company launched a self-developed CNC linear motor lathe directly driven by linear motor. At the 8th China International Machine Tool Show in 2003, it exhibited the VS1250 linear motor from Beijing Electric Power High Technology Co., Ltd. The machining center has a maximum spindle speed of 15000 r/min.
