Overview of the latest developments in CNC machine technology

CNC machine tools are moving towards high speed, high efficiency and high precision. To enhance market competitiveness, machine tool manufacturers in various countries have adopted many new technologies in the design and manufacture of CNC machine tools, such as linear motors, high-efficiency cooling systems, and multi-function machining systems. , open CNC systems and network manufacturing systems. These advanced technologies are currently used in new CNC machine tools.

1 linear motor

Advanced linear motor drives have been widely used in CNC milling machines and CNC lathes. It can not only perform high-speed cutting and fast chip removal of parts under the cutting conditions of feed speed of f=60m/min or more, but also improve the machining accuracy of parts. The linear motor has the characteristics of faster servo response speed, improved servo control accuracy and machine tool machining accuracy, and thus can greatly expand the machining capability of the CNC machine tool. The usual rotary-linear motion transmission system affects the machining quality of the part due to its inherent quality, inertia, lead, lag and vibration. The above problem does not exist when a linear motor is mounted on a CNC machine. At present, companies such as Mazak, Mori Seiki, Otsuka and Cincinnati Machine have used linear motors for new CNC machines, so that the feed rate of the machine reaches f=60m/min or more, and the rapid moving speed reaches f=120m/min. Up to 2g. At present, there are problems such as small bearing capacity and heat generation in the use of linear motors, which need to be improved in the future.

2 efficient cooling system

For CNC machines that perform high-speed cutting, each axis must be cut at a feed rate of f=60m/min, which causes the CNC machine with ball screw to generate high temperature during machining, which seriously affects the dimensional accuracy of the part and the machine tool. Positioning accuracy. The ball screw cooler developed by Hitachi Precision Machinery Co., Ltd. cools the coolant by transferring the coolant in the hollow ball screw to achieve the purpose of cooling the screw and stabilizing the machining size. The electronic cooler control system developed by Makino monitors the temperature rise of the ball screw due to friction and so on, keeping the ball screw temperature within the allowable range. In addition to cooling the ball screw, the temperature rise of the high-speed rotating spindle is also strictly controlled. Yamazen cooled the machine tool spindle, tool and machined parts through a spindle center hole with a coolant of p = 6.89 MPa. It not only ensures that the workpiece and the tool are not affected by the temperature rise, but also improves the service life of the tool, and can also smoothly discharge the chips and purify the processing environment. In order to avoid the influence of temperature rise on the guide rail, Hitachi and the bearing manufacturer jointly developed the guide grease of the grade Eco-Eco, which has the advantages of cooling, good lubrication, no harmful substances, automatic lubrication and no special equipment. . Many manufacturers have proved that it has good use effect and economic benefit.

3 multi-function processing system

It is an inevitable trend of manufacturing technology to complete all the processing steps of a part on one machine. The newly developed lathes have similar 4- to 5-axis machining functions on the machining center as well as high-power, multi-function B-axis machining systems and automatic tool changers, making the difference between lathes and machining centers increasingly diminishing. machine tool. The generation of multi-function machine tools is one of the signs of technological advancement in CNC machine tools.

4 high efficiency, high power spindle motor

In order to improve the cutting speed, quick response capability and control accuracy of the spindle motor of the machine tool, most CNC machines choose the integrated spindle AC induction spindle motor instead of the conventional split spindle motor decelerated by belt or gear. Recently, with the advancement of technology, a permanent magnet integrated spindle motor with rare materials has been newly developed. Because it can transmit torque more efficiently and with high power, there is a tendency to replace the inductive integrated spindle motor. According to the Yamazen manager, this 永久-containing permanent magnet integrated spindle motor has three advantages over the general-purpose inductive integrated spindle motor:

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