Lubrication Mode and Installation Steps of Spindle Bearing

Time：2021.06.10  Source：Roller Bearings Suppliers

Introduction to the functions of machine tool spindle bearings

Machine tool spindle bearing is the spindle bearing of precision machine tools and similar equipment, which can guarantee the working accuracy and performance of precision machine tools. The correct configuration of spindle bearings refers to the combination of bearing types and the arrangement of front and rear bearings. The different configuration determines the different load capacity, running speed, stiffness, temperature rise and service life of the machine tool spindle.

In particular, the influence on the stiffness and temperature rise is more significant, so the spindle bearing should be reasonably configured according to the requirements of the working characteristics of the machine tool. In terms of function and structure, spindle bearings can be divided into rolling bearings and sliding bearings.

Why need to Running-in?

Running-in is the purpose of the operation in order to make the bearing before officially make Angle, make its roller and race through the running-in, can have good contact conditions, to maintain the accuracy of bearings have good contact, and to avoid bearing the beginning in high-speed and heavy-load roller and raceway damage when using, thus improve the life and precision of the bearing as a result of the tapered roller bearing is not completely rolling contact, There is sliding between the end face of the roller and the shoulder of the inner ring. If the contact condition is not good, it is easy to appear the phenomenon of occlusion damage. Therefore, more attention should be paid to the running and running of this kind of bearing. Need WSBC 22219-E1, click here to learn more.

What is the function of the machine spindle?

Mechanical spindle refers to the shaft on a machine tool that drives the workpiece or cutting tool to rotate. Usually by the spindle, bearing and transmission parts (gear or pulley) and other components of the spindle. The machine is mainly used to support the transmission parts such as gear, belt pulley, transfer movement and torque, such as machine tool spindle; Some are used to clamp the workpiece, such as the mandrel. Most machine tools have spindle parts, except planers, broaching machines, and other machines whose main motion is linear. The motion precision and structural stiffness of spindle components are important factors to determine the machining quality and cutting efficiency.

Introduction of main spindle components

Spindle bearing is an important part of the CNC machine tool spindle. In the process of spindle transmission, it can support the rotation of the mechanical body and reduce friction. Bearing because of its type, structure, configuration and accuracy, as well as installation, adjustment degree of good or bad will have a direct impact on the performance of spindle components. In terms of function and structure, spindle bearings can be divided into rolling bearings and sliding bearings. According to the pressure mode of oil film generation, sliding bearings can be divided into the hydrodynamic bearing and hydrostatic bearing.

The rotating accuracy of rolling bearings in generally or good, and maybe high when working without clearance or preload. The stiffness is average or good, only related to the bearing type, and so is the carrying capacity. Poor vibration resistance performance, low and medium speed performance is good, high speed by fatigue strength, centrifugal force, temperature rise and other factors limited. Friction loss is small, noise is large, life is limited by fatigue strength. Production, use and maintenance are relatively simple, have been standardized and serialized, can be low cost mass production.

The rotating accuracy of the dynamic pressure bearing in general, but the accuracy is good. Stiffness and bearing capacity are high and increase with the increase of speed and load. Good seismic performance, medium and high-speed performance are good, low speed because can not form oil film, no bearing capacity, ultra-high-speed by temperature rise limit. Small friction loss, no noise, long life when infrequent start. The production cost is low, but the technical requirements are high, the factory's needs to make, use and maintenance are also more troublesome.

The hydrostatic bearing has high rotation accuracy and good retention. Stiffness and bearing capacity are very high, independent of the speed and load, and related to the throttling form and the relative pressure difference of the oil chamber. Excellent anti-seismic performance, suitable for various operating speeds, especially low speed and ultra-high-speed operation.Very small friction loss, no noise, very long life. In addition to its own cost, but also need a set of oil supply equipment, so the total cost is high, and the production process requirements are also high, the factory to make, use and maintenance more troublesome.

When choosing the type and combination of bearings to be used, the requirements of spindle components in all aspects, as well as the supply of bearings, costs, installation and debugging difficulties and other factors should be comprehensively considered. Under normal conditions, the spindle should be preferred rolling bearings, especially for vertical spindle, only when the spindle is placed horizontally, and the surface roughness of the workpiece is small, the sliding bearing is used. Click here to learn more about WSBC 22226 E.

How to fasten the inner ring of the bearing to the shaft?

In order to fasten the bearing inner ring on the shaft, the thread is generally processed on the shaft, and the nut is used for fastening. Although the verticality between the threaded part and the end face of the nut is very important, even for a single nut with high precision, the clearance between the shaft and the nut can cause deviation and tilt during fastening. This will lead to the bending of the shaft and bearing, so in order to ensure the rotation accuracy of the shaft, it must be adjusted. Nuts should be tightly tightened to prevent loosening.

In high speed and high precision spindle, in order to avoid the unbalance caused by nut tilt or thread clearance when the nut is fastened, the shaft sleeve fixing method is mostly used, and the axial fixing is carried out by the large surplus of the inner diameter of the shaft and the shaft sleeve. But compared with the nut fastening, it is easier to loosen under continuous operation, so it must be checked regularly.

When a wide spacer is placed between the combined angular contact ball bearings, if the tightening force of the nut is too large, the inner spacer will be deformed and the preload during installation will be greater than the set value.

To secure the outer ring in the axial direction, the gland is usually secured with bolts. If the fastening amount is too large or uneven, the outer ring raceway surface is easier to produce deformation. It is suggested that the gap between the gland and bearing seat end face should be adjusted between 0.01~0.05mm.

Note that when running at high speed, the interference of bearing and shaft increases, so does the required pressing force, and the fastening force of the nut must be increased accordingly.

How can I contact the bearing company?

Wuxi Spark Bearing Co., Ltd (Aka Spark Bearings) is the complete, one-stop Spherical roller bearings, supplier & manufacturer. All products are qualified and have passed the ISO 9001 qualification. Here are some popular types of Bearings, Send a quote and get the latest price of cheap bearings from Spark Bearings.