Bearing air cooling technology achieves high rigidity and ultra-high speed

In the 100-year history of NTN, the company has provided various mechanical products centered on bearings to the global market with the concept of 'contributing to the international community through new technology creation and new product development'. At present, NTN is in a leading position in the Japanese bearing market. NTN takes high-speed rail, wind power, machine tools, construction machinery, elevators and robots as key industries in the industrial field. The standard ULTAGE series is the basic rolling bearing standard series, providing more high-performance bearings to the industrial machinery market.

The machine tool refers to the equipment used to process materials and parts, so it is also called the 'mother machine'. In addition to the automobile industry, non-automotive industry, and energy industry, it is also responsible for the manufacturing of other industries in the world and supports the development of the world economy. In recent years, machine tool processing objects, processing methods, and users have gradually shown diversified machine tool performance requirements. On the basis of the previous requirements for high speed, high rigidity and high precision, further requirements such as compounding, miniaturization and environmental protection have been put forward. NTN has also contributed to the sustainable development of the world economy through the research and development, manufacturing and sales of precision bearings, which are important parts of machine tools.

The main shaft of a machine tool needs to have high rigidity and high speed performance when processing difficult-to-turn materials, molds, parts with complex shapes, and medical equipment. Especially in recent years, 5-axis machine tools and compound machine tools that integrate a variety of processing capabilities on one machine tool have become mainstream models in dealing with diverse processing. With the improvement of processing performance, the rigidity and high speed of the spindle bearing are affected. The requirements have also become higher and higher.

The bearings with air-cooled spacers for machine tool spindles introduced in this article have improved materials from previous conventional products , Heat treatment, optimization of internal design, improvement of lubrication surface and other measures are different. This product focuses on reducing the heat of the spindle and adopts the air-cooling spacer of the air-cooling technology developed by NTN. Therefore, the temperature difference between the inner and outer rings is effectively suppressed, and the speed is increased by 20% compared with conventional products (NTN high-speed angular contact ball bearings HSE series). In the case of oil-air lubrication and positioning preload, its dmn value (bearing pitch circle diameter mm×rotation speed r/min reaches 2.1 million, achieving a high level of high-speed rotation performance.

By ensuring that the inside of the bearing is assembled The pretension of the main shaft greatly improves the rigidity of the spindle, so that the processing performance can be improved in a variety of speed ranges. In addition, the use of a special spacer design can reduce the noise generated by the bearing due to lubrication and cooling air, and achieve low operation Noise. In addition, by improving the shape of the spacer ring, the noise generated by the lubrication or cooling air of the bearing during operation can also be reduced.

The structure of the bearing with air-cooled spacer ring is shown in the figure. The angular contact ball bearing is back to back In the outer ring spacer designed between the assembly (DB pairing), the environmentally friendly oil-air lubrication nozzle developed by NTN can reduce air volume, oil volume, and reduce noise. At the same time, the nozzle is also equipped with an independent air-cooled nozzle. The air cooling nozzle translates from the shaft core and is arranged at three positions on the circumference along the rotation direction of the shaft. The room temperature air ejected from the air cooling nozzle rotates along the rotation direction of the shaft and penetrates between the inner ring spacer and the outer ring spacer at the same time. This product is characterized by high speed performance, which is 20% higher than conventional products, with a dmn value of 2.1 million (oil-air lubrication, positioning preload); it has high rigidity to ensure the bearing preload when the main shaft is assembled. ; Noise is characterized by low noise. It can be used for machine tool spindles (compound machine tools, machining centers), testing machine spindles, etc.