The slewing drive we often say is actually a full-circle slewing reduction transmission mechanism integrated with a driving power source. It takes a slewing bearing as a drive follower and mechanism attachment. It makes one of the rings ( inner ring or outer ring) to be attached as the driving part, the driving source and the cover, and the other ring as the transmission follower and the connection base of the driven working part. In this way, it can make use of the characteristic of the slewing bearing which is a full-circle slewing connection to configure efficiently the driving power source and main transmission parts. And finally make it to be a universal reduction transmission mechanism that integrates the functions of rotation, reduction and driving, while having a simple structure and convenient manufacturing and maintenance. At present, there are many types of slewing drive devices. What are the factors to be considered when selecting a slewing drive device?
1. Magnitude, Direction and characters of the load
The slewing drive device is suitable for light loads, and the roller bearing is suitable for heavy loads and shock loads. When the rolling bearing is subjected to pure axial load, thrust bearing is generally selected; when the rolling bearing is subjected to pure radial load, deep groove ball bearing or short cylindrical roller bearing is generally selected; when the slewing device is subjected to pure radial load, and with not large axial loads, deep groove ball bearings, angular contact ball bearings, tapered roller bearings and self-aligning ball or spherical roller bearings can be selected; When the axial load is large, the angle contact bearing and tapered roller bearings ca be selected, or use a combination of radial bearings and thrust bearings, which are particularly suitable for extremely high axial loads or special requirements for greater axial rigidity.
2. Allowable speed
Due to big differences of types of slewing drive, bearings with low friction and low heat are suitable for high speeds generally. During the design, the slewing rolling bearing should considered to be work under the condition of lower than its limit speed.
When the bearing of the slewing drive device bears a load, elastic deformation occurs at the contact between the bearing ring and the rolling element. The amount of deformation is proportional to the load, and the ratio determines the rigidity of the bearing. Generally, the rigidity of the bearing can be improved by preloading the bearing; In addition, in the bearing design, considering the combination and arrangement of the bearing can also improve the support rigidity of the bearing.
4. Alignment performance and installation error
After the bearing is installed in the working position, it is often poor in installation and positioning due to manufacturing errors. At this time, the bearing is often subjected to excessive load due to the fishing degree and thermal expansion of the shaft, causing early damage. The self-aligning bearing can overcome the defects caused by the installation error by itself, so it is the bearing suitable for this purpose.
5. Installation and disassembly of slewing drive device
Tapered roller bearings, needle roller bearings and etc., belong to the type of bearing with separable inner and outer rings (so-called separate bearings), which are easy to install and disassemble.
It is a brief introduction to the factors that need to be considered when selecting the slewing drive device above. The slewing drive can be used in any situation that requires full rotation and variable speed requirements. When it is necessary to achieve greater torque power transmission and higher precision motion transmission Or when selecting a mechanism that requires a high degree of compact body structure and integration, slewing drive is the solution. In addition, the slewing drive device is convenient to install and saving space. When selecting the model, first consider whether the shaft radial load, overturning torque and other parameters are workable for use. Secondly, the final output speed of the slewing drive cannot exceed 3 revolutions during use, in order to ensure the product normal service life.