Introduction
The spindle of a machine tool is one of its most important components, and its performance directly affects the accuracy and efficiency of machine tool processing. The bearing selection is an important part of the design of the machine tool spindle. At present, the most widely used bearings in the machine tool spindle are rolling bearings. The application of rolling bearings in the design of machine tool spindles is characterized by a wide variety of bearing types and specifications, and the requirements for the use environment are also very strict.
Rolling bearing selection
The main performance of rolling bearings used in satellite spindles is its load-bearing capacity, rotation speed, temperature rise, vibration and noise level. At present, the most widely used rolling bearing in machine tool spindles is deep groove ball bearings. With the requirements of precision, high speed and high rigidity, the radial ball bearings and thrust ball bearings used by machine tool spindles are also increasing. In addition, when selecting bearings, the requirements for bearing structures, materials, lubrication and sealing methods should also be considered.
For machine tool spindle bearings, the load-carrying capacity is closely related to the bearing radial dynamic load bearing capacity and the axial dynamic load bearing capacity. The radial dynamic load bearing capacity is a measure of the radial load bearing capacity of the bearing. The higher the axial dynamic load bearing capacity of the bearing, the better its load-bearing capacity. The spindle used in the machine tool must ensure that the bearing is not subjected to excessive load. At the same time, due to the influence of the influence coefficient of the bearing, the load-carrying capability of the bearing will decrease with the increase of the rotation speed of the spindle, and the bearing that meets the load-carrying requirements must have an adequate minimum constant speed.
The temperature rise of the bearing is closely related to the running stability of the spindle. In actual use, the increased temperature of the bearing will reduce the fatigue life of the bearing, the lubrication performance will decrease, and the bearing vibration and noise will also increase. When selecting bearings, the accuracy level of the bearing should also be considered. The higher the accuracy level of the bearing, the smaller the load fluctuation, the better the bearing performance. In addition, with the requirements of high-speed operation, the axial stiffness of the bearing should be considered. Generally, the bearing can have high rigidity performance under both radial and axial loads.
In terms of lubrication, the selection of bearing lubricants is also an important issue. During the operation of the spindle, the lubricating oil can help reduce the friction between the sliding surface and reduce the influence of load, temperature and vibration on the bearing, so that the bearing can work safely and reliably. Generally speaking, the selection of grease depends on the operating temperature and speed of the bearing. The operating temperature of the bearing is mainly affected by the surface roughness of the bearing raceway, its housing fit, the bearing heat dissipation condition, the outside temperature and other factors. Bearing lubrication can guarantee the service life of the bearing, reduce the bearing temperature and reduce the bearing vibration, so it needs to be considered carefully.
In terms of sealing, for the dual-use spindle of machine tool, external sealing device can be installed to reduce the impact of external foreign matter on the bearing and lubricating oil, reduce the maintenance rate of the bearing, and protect the bearing from dirt and dust to a certain extent, thus improving the bearing service life.
Conclusion
In summary, the selection of rolling bearings for machine tool spindles has certain requirements. The selection process should consider the factors such as load-bearing capacity, rotation speed, temperature rise, vibration and noise, bearing structure, materials and lubrication and sealing methods. Only by selecting the appropriate bearing can we meet the requirements of machine tool spindle.
