As an important part of the machinery equipment industry, the machine tool industry plays a pivotal role in the development of the entire national economy. According to statistics, in general machine manufacturing, the processing workload undertaken by machine tools accounts for about 40% to 60% of the total manufacturing workload. Therefore, the development level of the machine tool industry is usually a sign of a country's industrial development level. With the increasing development of modern manufacturing, customers have higher and higher requirements for industrial master machines-machine tools. At present, the continuous emergence of new materials, new processes, and new equipment has brought many challenges to the processing capabilities of machine tools. In order to meet the processing of the above-mentioned structural parts, modern machine tools are moving towards 'high-speed, precise, composite, and intelligent' The direction of development.

With the deepening of the upgrading of my country’s industrial structure, the machine tool industry also shows the trend of industrial structure upgrading, that is, the proportion of CNC machine tools is gradually increasing. In the field of CNC, high-end CNC machine tools (such as heavy-duty machine tools, The proportion of intelligent machine tools, etc.) is also rising. Heavy machine tools are mainly used for national energy (thermal power, hydropower, nuclear power, wind power), shipbuilding, construction machinery, metallurgy, aerospace, military, and transportation (railroads, automobiles) And other major industrial pillar industries and national key engineering project services, national key engineering projects provide a broad market for heavy-duty machine tools.

This article mainly introduces how to choose the bearing type used in the spindle bearing and turntable bearing in the machine tool.

Spindle bearing

As a key component of the machine tool, the performance of the spindle will directly affect the rotation accuracy, speed, rigidity, temperature rise, noise and other parameters of the machine tool, which will affect the processing quality of the workpiece, such as the Dimensional accuracy, surface roughness and other indicators. Therefore, in order to maintain excellent machining capabilities of machine tools, high-performance bearings must be used. The bearing accuracy used on the machine tool spindle should be ISOP5 or above (P5 or P4 is the ISO accuracy grade, usually from low to high as P0, P6, P5, P4, P2), and for high-speed, CNC machine tools, machining centers, etc. For the spindle support of high-precision machine tools, the accuracy of ISOP4 or above is required; spindle bearings include angular contact ball bearings, tapered roller bearings, and cylindrical roller bearings.

Precision angular contact ball bearings

Among the above-mentioned types of bearings, precision angular contact ball bearings are the most widely used. We all know that the rolling elements of angular contact ball bearings are balls; because it is a point contact (different from the line contact of roller bearings), it can provide higher speed, lower heat generation and higher rotation Accuracy. In some ultra-high-speed spindle applications, hybrid bearings with ceramic balls (usually Si3N4 or Al2O3) are also used. Compared with traditional fully hardened steel balls, the characteristics of ceramic ball materials endow ceramic ball bearings with high rigidity, high speed, high temperature resistance, and long life, so as to meet the needs of high-end customers for machine tool bearing products.

As far as the contact angle of angular contact ball bearings is concerned, the more popular ones are the contact angles of 15º and 25º; usually the contact angle of 15º has a relatively high speed performance, while the contact angle of 25º has a higher axial Carrying capacity. Because the choice of preload has a great influence on the application of precision angular contact ball bearings, for example, in high load and high rigidity occasions, medium or heavy bearing preloads are generally selected; and for some high speed and high precision applications In the early selection of bearings, we need to pay attention to selecting the appropriate preload. Generally, light preload is more common. Preload is generally divided into three types: light, medium, and heavy; in order to facilitate the use of customers, several major bearing manufacturers in the world generally provide bearings with pre-ground and preloaded bearing ends, which is what we usually call universal precision matching Angular contact ball bearing form. This type of bearing eliminates the customer's preload adjustment, thereby saving installation time.