Characteristics and technical information of linear bearings
Linear bearings are a low-cost linear motion system used in conjunction with cylindrical shafts with infinite travel. Due to the point contact between the bearing ball and the shaft, the load is small. The steel ball rotates with minimal frictional resistance, allowing for high-precision smooth motion.
Linear bearings are widely used in precision equipment such as electronic equipment, tensile testing machines, and digital three-dimensional coordinate measurement equipment, as well as sliding components of industrial machinery such as multi axis machine tools, punches, tool grinders, automatic gas cutting machines, printers, card sorting machines, and food packaging machines.
Lubrication and friction
Grease lubrication
Inject anti-corrosion oil inside the linear bearing. If lubricating with grease, first remove the anti-corrosion oil with kerosene or organic solvent, air dry, and then add lubricating grease.
It is recommended to use lithium soap grease with a viscosity mark of N0.2
Oil lubrication
If oil lubrication is used, it is not necessary to remove the anti-corrosion oil. According to temperature changes, ISO viscosity grade VG15-100 lubricating oil can be selected
The shaft lubrication can be supplied from the oil supply pipe or from the oil hole on the outer bearing seat. Due to the fact that the sealing ring scrapes off the lubricating oil, oil lubrication is not suitable for bearings with sealing rings without holes.
Friction coefficient
From Figure 5, it can be seen that the friction coefficient of motion ranges from 0.001 to 0.004. The energy loss caused by friction is minimal. When the movement speed is less than 60m/min, the temperature effect can be ignored. The frictional force can be obtained by the following equation:
F= ц.· P+fs
F: Friction force (N) *: Sealing resistance (2-5N)
P: External load (N) ц: Friction coefficient
Installation
Fit clearance
Suggested fit tolerances for the inner hole of the bearing seat and the diameter of the optical shaft.
Usually, bearings cannot be preloaded, but high-precision and light preloads can be added to the bearings. However, negative diameter tolerances should not exceed the data in the table.
Fit clearance between bearing housing and shaft and bearing
Installation of bearing box
Standard type
Several methods for installing bearing housings with snap rings and fixing plates.
Installing bearings with positioning screws can cause deformation of the bearing sleeve and should be avoided as much as possible.
. Flange type
When installing flange type linear bearings, the surface accuracy of the holes in the bearing box that match them must be accurate.
Adjustable type (small opening type)
The opening on the bearing and the bearing box is perpendicular to each other, and a uniform preload in the circumferential direction can be obtained.
Large opening type
If used in conjunction with a suitable bearing seat, large opening bearings can also be adjusted for clearance or even preloaded lightly.
Precautions during installation
When installing the linear bearing into the bearing seat, auxiliary work should be used to avoid directly hitting the end face or sealing ring. The bearing should be evenly introduced, and a buffer plate should be used to gently tap into the installation
To thread the optical axis into a linear bearing, it is necessary to align the axis with the centerline of the bearing. If the shaft is tilted and inserted, the ball may fall off or cause deformation of the cage, causing damage to the linear bearing
The applied load should be evenly distributed across the entire bearing, especially when subjected to instantaneous loads, two or more bearings should be used. Linear bearings do not bear rotating loads, otherwise they can cause accidents.