Analysis of bearing technology of high performance

Analysis: China's high-performance machine tool bearing technology

the machine tool spindle is the core component of the machine tool, and its function is to drive the tool (grinding wheel) or workpiece to rotate to achieve high-speed precision machining. With the continuous improvement of the machining accuracy and efficiency of machine tools through the special manufacturing process in modern industry, the requirements of machine tools for the performance of spindle are also higher and higher. The traditional concept of high-speed spindle has been difficult to fully describe the technical connotation of machine tool spindle

high performance machine tool spindle refers to a machine tool spindle with good matching characteristics of speed, accuracy, stiffness, power and torque, high reliability and high performance price ratio on the premise of meeting the machining accuracy and efficiency

machine tool spindles can be divided into rolling bearings (angular contact ball bearings, roller bearings), liquid sliding bearings (dynamic pressure bearings, static pressure bearings, dynamic and static pressure bearings), gas bearings and magnetic bearings according to the type of bearings used, and can be divided into mechanical spindles and electric spindles according to the connection mode with motors

electric spindle is a new type of spindle component that integrates the spindle function of machine tool and the function of motor in structure. It eliminates the belt transmission or gear transmission link, and has the advantages of high speed, high precision, wide speed regulation range, low vibration noise, fast start and quasi stop. Replacing the traditional mechanical spindle with electric spindle is the general trend of the development of machine tool industry

the front cover of the box adopts ultra light carbon fiber composite motorized spindle, which can be divided into asynchronous motorized spindle and permanent magnet synchronous motorized spindle according to the type of motor

from the objective demand of the machine tool industry, angular contact ball bearing motorized spindle, liquid (dynamic) hydrostatic bearing motorized spindle and gas shaft should be taken out and ground. Piston and piston sleeve bearing motorized spindle is not only the focus of market development, but also the hotspot of academic research. Angular contact ball bearings are the most suitable, but in fact, these materials have been eliminated in many other regions of the world. High speed rolling bearings have the advantages of low friction resistance, low power consumption, low cost, easy serialization and standardization, and their high limit speed, high precision and high stiffness. They have been widely used in machining centers, CNC milling machines, lathes, internal grinder and high-speed engraving and milling machines, The main technical difficulty lies in improving the accuracy, service life and reliability. The liquid (dynamic) hydrostatic spindle is supported by the liquid "oil film", which has significant "error homogenization effect" and damping and vibration reduction. The rotation accuracy is much higher than that of the rolling bearing spindle. Its rigidity is high, the wear is small, and the service life is long. It has been widely used in precision and ultra precision machine tools. Its main technical difficulty is to control the temperature rise and thermal deformation of the spindle at high speed. Gas bearing motorized spindle is supported by "air film". Its rotation accuracy and limit speed are higher than that of liquid (dynamic) hydrostatic motorized spindle and rolling bearing motorized spindle. Its thermal stability is good. It is an indispensable core component of ultra precision machine tools and printed circuit board (PCD) drilling machines. Its shortcomings are low bearing capacity and high process requirements

magnetic bearing is also an important spindle support mode, with high limit speed and no wear during operation. Its technical difficulty lies in how to improve the dynamic stiffness and damping performance, and ensure high machining accuracy while realizing high speed. The core research content of magnetic suspension spindle is the control of mechanical system characteristics and electromagnetic characteristics