New Technology Development of High Reliability Single Row Cylindrical Roller Bearings for Machine Tool Spindles

The use of a new type of roller guide cage to improve the production efficiency and reliability of the spindle-the new technology of machine tool spindle TIMKEN bearings developed by Seiko (hereinafter referred to as NSK) can reduce the workload during assembly and running-in operation, and improve the reliability of the spindle. The technology will be exhibited at the "CIMT 2021 17th China International Machine Tool Show" in Beijing on April 12, 2021. Combining market feedback, we will strive to achieve mass production as soon as possible after 2021.

Development background

Single-row cylindrical roller bearings are the key components of the machining center spindle. In order to optimize the distribution of the grease inside the bearing during grease lubrication, long-term running-in is essential, which becomes a bottleneck for improving production efficiency. In addition, under the condition of oil-air lubrication*1, the excessive temperature rise of the bearing during low-speed operation is also an urgent issue to be solved. To solve such problems, although the rolling element guide method can be used to stabilize the cage position, it is easy to cause the cage to bear excessive load and cause early damage. Therefore, the outer ring guide method is generally used in the industry. 

Characteristics of the new technology

1. Shorten the running time of grease

NSK successfully developed the rolling element guide cage, which has the same durability as existing products. By improving the shape of the cage and improving the discharge performance of excess grease, compared with the general outer ring guide cage, the running-in time of grease lubrication can be shortened by about 70% at the maximum.

2. Reduce abnormal temperature rise during oil-air lubrication

Under the condition of oil-air lubrication, the traditional outer ring guidance method is difficult to solve the excessive temperature rise caused by too much lubricating oil inside the bearing at low speed. The rolling element guide method can solve the above problems and realize the stable operation of the main shaft during oil-air lubrication.

3. Improve the reliability of the rolling element guide cage

Aiming at the problem of easy damage to the cage guided by the rolling elements, NSK optimized the material and shape of the cage to improve the durability (reliability) of the cage guided by the rolling elements.

Development product effect

This technology can shorten the assembly time of grease-lubricated spindles and improve the production efficiency of machine tool manufacturers. At the same time, the abnormal temperature rise during oil-air lubrication is reduced, the strength of the roller guide cage is improved, and high reliability is achieved.

Use

In machining centers for forming automotive parts and general mechanical parts, the electric spindle with a built-in motor generates axial elongation due to self-heating. Therefore, cylindrical roller bearings are generally used at the back end of the spindle. The new technology developed by NSK this time is most suitable for the back-end support bearing of the spindle.