RA Series

Introduction of RA Series

Our cross-roller bearings, because the divided inner ring or outer ring, after the rollers and spacers are installed, is fixed with the cross-roller ring to prevent separation from each other, so install the cross-roller shaft It is easy to operate when ringing. Since the rollers are arranged in a cross, only one set of cross roller rings can bear loads in all directions. Compared with the conventional model, the rigidity is increased by 3 to 4 times. At the same time, because the inner ring or outer ring of the cross roller bearing has a two-part structure, the bearing gap can be adjusted, and even if preload is applied, high-precision rotational movement can be obtained.

The classification and model series of the crossed roller bearings we produce:

• RA type (outer ring split, ultra-thin type)
• The RA series model is a compact type that reduces the thickness of the RB inner and outer rings to the limit. It is suitable for parts that require light weight and compact design, such as rotating parts of robots and manipulators.

Details

• With excellent rotation accuracy
  The internal structure of the crossed roller bearing adopts the rollers arranged in a 90° mutually perpendicular crosswise arrangement.
  Spacer retainers or spacer blocks are installed between the rollers to prevent the rollers from observing each other when they are tilted. In addition, there is no square contact phenomenon or locking phenomenon of the roller; at the same time, because the inner and outer ring is a divided structure, the gap can be adjusted, even if preload is applied, high-precision rotational movement can be obtained.
• Simplified operation and installation
  The outer ring or inner ring, which is divided into two parts, is fixed in place after the rollers and cages are installed, so the operation during installation is very simple.
• Withstand large axial and radial loads
  Because the rollers are arranged perpendicular to each other through spacers on the 90° V-groove rolling surface.
• Significantly save installation space
  The size of the inner and outer rings of the cross roller bearing is miniaturized to a small limit, especially the ultra-thin structure is a small size close to the limit, and has high rigidity, so it is suitable for the joint or rotating part of industrial robots, and the rotating work of machining centers. It has a wide range of uses such as tables, rotating parts of manipulators, precision rotating tables, medical instruments, measuring instruments, and IC manufacturing equipment.
• High speed capability
• Reduce shaft length and processing costs, thermal expansion causes limited changes in geometric dimensions
• Adopt nylon divider, low moment of inertia, low starting torque, easy to control angle indexing
• Optimized pre-tightening force, high rigidity, high precision of guiding roller operation
• Carburized steel provides excellent impact resistance and surface abrasion resistance
• Simple but well lubricated

Quality Standard

Rockewell Bearings has added parameters that are not defined by ISO/ABEC for customers, including preload tolerances, functional tests, traceability and micron codes, cleanliness, raceway curvature, balls, etc. and roundness, surface processing (function And non-functional surfaces), steel specifications, cage trim and design, and installation chamfering. The definition of these parameters improves the quality of precision angular contact ball bearing products, thereby improving the performance of machine tool spindles.
The element of precision angular contact ball bearings is the cage, which is very important for machine tool bearings. The performance of the cage will affect the stability of machine tool bearings under high-speed rotation. The standard cage produced by Rockewell is made of phenolic resin. The internal design and the tolerance of the pocket gap are tight and the guide surface is controlled to ensure the stability of the cage during high-speed operation, lubrication and dynamic load.
The two elements of precision angular contact ball bearings are cleanliness, which is very important for precision angular contact ball bearings. Generally, the parts of the bearing products must be cleaned with a multi-solvent for 3 hours to prevent impurities from entering the bearing and prevent inherent pollution sources. In addition, the non-working surface of the bearing must be ground to ensure that the bearing is free of impurities before leaving the factory. Therefore, the bearing products produced by Rockewell can increase the normal operating time of the machine tool.
There are two main structural design methods for precision angular contact ball bearings: the high-rigidity WI series and the high-speed HX series to meet the requirements of different applications. The basic, open Rockewell bearing design has a higher spindle speed and greater dynamic radial stiffness, so the spindle can cut more material in a shorter time while ensuring excellent finished product tolerances. These improvements are attributed to the combination of the ball body and the precision engineering design of the raceway profile, which improves the processing rate.