Analysis on the status quo of the technical connotation of high-performance machine tool bearings in my country

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

High-performance machine tool spindle refers to a machine tool spindle with good speed, precision, rigidity, power and torque matching characteristics, high reliability, and high cost performance under the premise of satisfying processing accuracy and processing efficiency.

The main shaft of machine tool can be divided into rolling bearing (angular contact ball bearing, roller bearing), liquid sliding bearing (dynamic pressure bearing, static pressure bearing, dynamic and static pressure bearing), gas bearing and magnetic suspension bearing according to the type of bearing used. According to the connection with the motor, it can be divided into mechanical spindle and electric spindle.

The electric spindle is a new type of spindle component that integrates the function of the machine tool spindle with the motor function. It eliminates the need for belt transmission or gear transmission. It has high speed, high precision, wide speed adjustment range, and low vibration and noise. , It has the advantages of quick start and exact stop. Replacing traditional mechanical spindles with electric spindles is a major trend in the development of the machine tool industry.

The electric spindle can be divided into asynchronous electric spindle and permanent magnet synchronous electric spindle according to the type of motor.

From the perspective of the objective needs of the machine tool industry, angular contact ball bearing electric spindles, liquid (dynamic) static pressure bearing electric spindles and gas bearing electric spindles are not only the focus of market development, but also the focus of academic research. Angular contact ball bearings are the most suitable for high-speed rolling bearings. They have the advantages of low friction resistance, low power consumption, low cost, and easy serialization and standardization. They have high limit speed, high precision, and high rigidity. They are used in machining centers, CNC milling machines, Lathes, internal grinders, and high-speed engraving and milling machines have been widely used. The main technical difficulty lies in improving the accuracy, life, and reliability. The liquid (dynamic) and static pressure spindle is supported by a liquid oil film, which has significant error equalization 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 life is long. The machine tool has been widely used, and its main technical difficulty lies in controlling the temperature rise and thermal deformation of the spindle at high speed. The gas-bearing electric spindle is supported by a gas film, and the rotation accuracy and limit speed are higher than the liquid (dynamic) static piezoelectric spindle and the rolling bearing electric spindle. Its thermal stability is good, and it is not suitable for ultra-precision machine tools and printed circuit board (PCD) drilling machines Indispensable core components, its shortcomings are low carrying capacity and high process requirements.

Magnetic suspension bearings are also an important type of spindle support method, with high limit speed and no wear during operation. The technical difficulty lies in how to improve dynamic stiffness and damping performance to achieve high speed while ensuring high machining accuracy. The core research content of the magnetic levitation spindle is the control of mechanical system characteristics and electromagnetic characteristics.