Precision bearings are mainly used in the following three parts of machine tools: spindle, ball screw and ordinary drive shaft. The accuracy of rolling bearings is usually divided into five grades: P0, P6, P5, P4 and P2.
Bearings used on precision machine tool spindles should be rated P5 and higher. For the spindle support of high-speed and high-precision machine tools (such as CNC machine tools and machining centers), P4 and higher grade super-precision bearings should be selected.
As the basic component of the machine tool, the performance of the spindle bearing directly affects the speed, rotation accuracy, stiffness, anti-vibration cutting performance, noise, temperature rise and thermal deformation of the machine tool, which in turn changes the machining accuracy and surface quality. Therefore, high-performance machine tools must be equipped with high-performance precision bearings.
Machine tool spindle bearings usually have six structural types: deep groove ball bearings, angular contact ball bearings, cylindrical roller bearings,thrust angular contact ball bearings, tapered roller bearings and thrust bearings. However, with the development of numerical control technology and the increasing requirements for processing speed, precision and environmental protection, the spindle bearings of mathematically controlled machine tools are limited to four types of structures: angular contact ball bearings, cylindrical roller bearings,thrust angular contact balls Bearings and tapered roller bearings.
Later, with the higher requirements for the processing speed of precision bearings, the precision bearing materials are also different, and ceramic materials gradually attract people's attention. This is because ceramic materials have the advantages of low density, high elastic modulus, low thermal expansion coefficient, wear resistance, high temperature resistance, corrosion resistance and other excellent characteristics, so they become ideal materials for manufacturing high-speed precision bearings. However, from the current situation, machining ceramic materials is challenging, so most precision ceramic bearings are ceramic rolling elements, and the inner and outer rings are still made of chrome steel hybrid ceramic ball bearings.
Ball Screw Bearings
As a correct, efficient and sensitive transmission element, the ball screw should not only use high-precision screws, nuts and balls, but also select precision bearings with high axial rigidity, small friction torque and high running accuracy. In the past, ball screw supports commonly used bidirectional thrust angular contact ball bearings, tapered roller bearings, needle roller and thrust composite roller bearings, deep groove ball bearings and thrust ball bearings.
Ordinary drive shaft bearing
Rolling bearings mounted on wide drive shafts are used in machine tools. Its requirements and selection are the same as ordinary mechanical transmission bearings. It only needs to meet the requirements of strength and service life, and the speed does not exceed the specified limit speed of precision bearings.