What is a crossed roller bearing? What are the installation and characteristics of crossed roller bearings?
【1】 A crossed roller bearing is a special type of bearing with a split inner ring and a rotating outer ring.
The split inner ring or outer ring is fixed to the cross roller ring after the rollers and spacer are installed to prevent separation, so the installation of the cross roller ring is simple. Since the rollers are arranged crosswise, only one set of cross roller rings can withstand loads in all directions, and the rigidity is increased by 3-4 times compared to conventional models. At the same time, since the inner ring or outer ring of the crossed roller bearing is a two-split structure, the bearing clearance can be adjusted, and even if preload is applied, high-precision rotation can be obtained.
In a crossed roller bearing, since the cylindrical rollers are arranged perpendicular to each other on the top through the spacer, a single crossed roller bearing can withstand loads in all directions, such as radial loads, axial loads, and moment loads. The size of the inner and outer rings is minimized, especially the ultra-thin type is close to the limit of small size, and has high rigidity. Therefore, its special structure is usually used as a joint bearing in industrial robots. Therefore, it is most suitable for the joints or rotating parts of industrial robots, rotary tables of machining centers, rotating parts of manipulators, precision rotary tables, medical machines, measuring instruments, IC manufacturing devices, etc.
The rollers of the crossed roller bearings are arranged at right angles to each other between the inner and outer wheels. They can bear loads from all directions at the same time (such as axial, thrust or momentum loads). Because the rollers are in linear contact with the track surface, the possibility of elastic deformation of the bearing under load is very small. This type of bearing is widely used in industrial automatic robots, working machinery and medical facilities, etc., where high rigidity, tightness and high speed are required to ensure precision.
Crossed roller bearings are divided into two categories: one is the crossed cylindrical roller bearing and the other is the crossed tapered roller bearing. They have been widely used in recent years due to their own special features and advantages that are incomparable to other bearings.
【2】 Crossed roller bearing installation order
Inspection of parts before installation Clean the bearing seat or other installation parts to remove dirt and confirm whether the burrs of each part have been removed.
2. Insert into the bearing seat or shaft. Since it is a thin-walled bearing, it is easy to tilt when inserted. Please use a plastic hammer to find the level while tapping evenly in the circumferential direction. Insert it little by little until you can confirm that it is completely close to the contact surface by sound.
3. Installation of side clamping flange
(1) After placing the side clamping flange in place, shake it back and forth in the circumferential direction several times to adjust the position of the mounting bolts.
(2) Install the clamping bolts. When tightening the bolts by hand, confirm that there is no difficulty in screwing in the bolts due to deviation of the bolt holes.
(3) The tightening of the clamping bolts can be divided into 3 to 4 stages from temporary tightening to formal tightening, and they should be tightened repeatedly in the order of the diagonal lines (as shown in the figure below). When tightening the clamping bolts of the two-part inner ring or outer ring, the outer ring or inner ring of the whole body can be slightly rotated during the tightening process to correct the two-part parts.
【3】 Characteristics of Crossed Roller Bearings
The cross roller bearings are easy to install because the divided inner ring or outer ring is fixed together with the cross roller ring after the rollers and spacers are installed to prevent separation. Since the rollers are arranged crosswise, only one set of cross roller rings can withstand loads in all directions, and the rigidity is increased by 3-4 times compared to conventional models. At the same time, because the inner ring or outer ring of the cross roller bearing is a two-part structure, the bearing clearance can be adjusted, and high-precision rotational motion can be obtained even if preload is applied.
1. Excellent rotation accuracy
The internal structure of the cross roller bearing adopts rollers arranged perpendicularly at 90°.
A spacer or spacer block is installed between the rollers to prevent the rollers from rubbing against each other due to the inclination of the rollers. In addition, there will be no contact or locking of the rollers. At the same time, because the inner and outer rings are divided, the gap can be adjusted, and high-precision rotation can be obtained even if preload is applied.
2. Simplified operation and installation
The outer ring or inner ring divided into two parts is fixed together after the rollers and the retainer are installed, so the installation operation is very simple.
3. Bear large axial and radial loads
Because the rollers are arranged perpendicularly to each other through the spacer on the 90° V-groove rolling surface.
4. Greatly save installation space
The inner and outer rings of the cross roller bearing are miniaturized to the minimum, especially the ultra-thin structure is close to the limit of small size, and has high rigidity, so it is most suitable for the joints or rotating parts of industrial robots, rotary tables of machining centers, rotating parts of manipulators, precision rotary tables, medical instruments, measuring instruments, IC manufacturing devices and other wide applications.
5. High speed capability
6. Reduce shaft length and processing costs, and the change of geometric dimensions due to thermal expansion is limited
7. Use nylon separators, low moment of inertia, low starting torque, and easy to control angular division
8. Optimize preload, high rigidity, and high running accuracy of guide rollers
9. Carburized steel provides excellent impact resistance and surface wear resistance
10. Simple but fully lubricated
