- Hello Customer - Log in or Register!
[World first! Proprietary bearing air-cooling technology for both high rigidity and ultra high-speed rotation!]
NTN Corporation (hereafter, NTN) has developed the “Machine Tool Main Spindle Bearing with Air Cooling Spacer” by applying its proprietary air-cooling technology to bearing for main spindles of machine tools to ensure high rigidity of the main shafts, while also achieving the world's highest standard of high-speed rotational performance.
The main spindles of machine tools require a high level of rigidity and high-speed rotation for machining difficult-to-cut materials, moldings, complex shapes, components for medical equipment and other parts. More specifically, machine tools need to be able to machine a wide range of work pieces in recent years, with 5-axis machining centers comprising of numerous machining functions in a single unit, or complex processing units becoming mainstream. This increase in machining functionality also increases the need for high-speed rotation with a higher rigidity.
The newly developed “Machine Tool Main Spindle Bearing with Air Cooling Spacer” focuses on reducing heat generated on main spindles with the “air cooling spacer” using NTN's proprietary air cooling technology, instead of taking the more conventional approach of modifying materials or heat treatment, changing the internal design or improving the lubrication surface. This limits the difference in temperature between the inner and outer rings, improves the high-speed rotational performance by 20% compared to conventional products (High-speed Angular Contact Ball Bearings), and achieves a dmn value*1 of 2.1 million to achieve the world's highest standard high-speed rotational performance with air-oil lubrication and fixed-position preload.
A preload could not be applied to the internals of conventional bearings with an inner diameter of φ70 and rotational speed of 23000 min-1 (dmn value of 2.1 million) after assembly, however a preload of up to 1300 N can be applied to the developed product. This major increase in main spindle rigidity during assembly contributes to better machining functions over a wider range of speeds. Increases to the noise generated when cooling the main spindle has been limited by optimizing the internal design of the “air cooling spacer” to retain the same level of performance as the previous “Eco-friendly Air-Oil Lubricated Angular Contact Ball Bearings.”*2
The developed product will be exhibited at “JIMTOF2014 The 27th Japan International Machine Tool Fair” held at Tokyo Big Sight from October 30 to November 4, and proposed to various machine tool manufacturers for the development of next-generation main spindle systems.
*1) Index that represents bearing rotation performance, bearing pitch circle diameter (mm) x rotational speed (mm-1)
*2) Precision Rolling Bearings Cat. No. 2260/E “Eco-friendly Air-Oil Lubricated Angular Contact Ball Bearings”
Features
(1) High-speed rotational performance: 20% improvement compared to conventional products, dmn value of 2.1 million
(Air-oil lubrication and fixed-position preload, world's highest standard)
(2) High rigidity: sufficient bearing preload when assembling main spindles (up to 1300 N)
(when setting maximum rotation speed of conventional products)
(3) Noise characteristics: low noise, equivalent to “Eco-friendly Air-Oil Lubricated Angular Contact Ball Bearings”
(E.g.: bearing inner diameter 70 mm x 23000 min-1/h, 93 dBA)
Applications
Machine tool spindles (complex processing units, machining centers), tester spindles, etc
Product photo
Example of main dimensions: φ70 × φ110 × 62 mm (bearing: back-to-back)
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 23160BK+AH3160 NTN | 280 | 192 | |
| 24060BK30+AH24060H NTN | 280 | 184 |