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Super precision Spindle Bearings for Machine Tool

Views: 10     Author: Site Editor     Publish Time: 2022-02-15      Origin: Site

Spindle bearings


A shaft system consists of more than just bearings. Associated components like the shaft and housings are integral parts of the overall system. The lubricant and sealing elements also play a crucial role. To maximize bearing performance, the correct amount of an appropriate lubricant must be present to reduce friction in the bearing and protect it from corrosion. Sealing elements are important because they keep the lubricant in and contaminants out of the bearing. This is particularly important since cleanliness has a profound effect on bearing service life. Therefore, TKW manufactures and sells a wide range of industrial seals and lubrication systems.


As a key part of the machine tool, the performance of the spindle will directly affect the parameters such as the rotation accuracy, speed, rigidity, temperature rise and noise of the machine tool, which in turn will affect the processing quality of the workpiece, such as the dimensional accuracy of the parts, surface roughness and other indicators. Therefore, in order to maintain excellent machine tool processing capability, high-performance bearings must be used. The bearing accuracy used on the machine tool spindle should be ISO P5 or above (P5 or P4 is the ISO accuracy grade, usually P0, P6, P5, P4, P2 from low to high), while for CNC machine tools, machining centers and other high-speed , For the spindle support of high-precision machine tools, the accuracy of ISO P4 or above must be selected; the spindle bearings include angular contact ball bearings, Double direction angular contact thrust ball bearings,Axial-radial cylindrical roller bearings, Angular contact thrust ball bearings for screw drives,tapered roller bearings, and cylindrical roller bearings.


super precision bearings


Super precision angular contact ball bearings

Among the above-mentioned bearings, precision angular contact ball bearings are the most widely used. We all know that the rolling elements of angular contact ball bearings are balls; because it is a point contact (different from the line contact of roller bearings), it can provide higher rotational speed, less heat generation and higher rotation precision. In some ultra-high-speed spindle applications, hybrid bearings with ceramic balls (usually Si3N4 or Al2O3) are also used. Compared with the traditional fully hardened steel ball, the characteristics of the ceramic ball material endow the ceramic ball bearing with the characteristics of high rigidity, high speed, high temperature resistance and long life, so as to meet the needs of high-end customers for machine tool bearing products.


As far as the contact angle of angular contact ball bearings is concerned, the more popular ones are 15° and 25° contact angles; usually 15° contact angle has relatively high speed performance, while 25° contact angle has higher axial Carrying capacity. Because the choice of preload has a great influence on the application of precision angular contact ball bearings, for example, in high-load, high-rigidity occasions, medium or heavy bearing preload is generally selected; for some high-speed, high-precision applications , In the early selection of bearings, we need to pay attention to selecting the appropriate preload, generally light preload is more common. Preload is generally divided into three types: light, medium and heavy; in order to facilitate the use of customers, several major bearing manufacturers in the world generally provide bearings with pre-ground bearing end faces and preloaded bearings, which is what we usually call universal matching precision. Angular contact ball bearing form. This type of bearing eliminates the need for customer preload adjustment, thus saving installation time.


high precision bearings


Super Precision Cylindrical Roller Bearings

In the application of machine tool spindles, double row precision cylindrical roller bearings are also used, usually in combination with precision angular contact ball bearings or thrust bearings. Such bearings can withstand larger radial loads and allow higher rotational speeds. The two rows of rollers in the bearing are arranged in a cross manner, and the fluctuation frequency during rotation is greatly increased compared with that of the single row bearing, and the amplitude is reduced by 60%~70%. This type of bearing usually has two forms: NN30, NN30K two series bearings have ribs on the inner ring, and the outer ring can be separated; NNU49, NNU49K two series bearings have ribs on the outer ring, and the inner ring can be separated, of which NN30K and NNU49K series The inner ring is a tapered hole (taper 1:12), which cooperates with the tapered journal of the main shaft and moves the inner ring axially to expand the inner ring, so that the bearing clearance can be reduced or even preloaded (negative clearance). state). Cylindrical bore bearings are usually shrink-fit, using interference fit to reduce bearing clearance, or preloading the bearing. For NNU49 series bearings with separable inner ring, the raceway is generally finished after the main shaft is installed on the inner ring to improve the rotation accuracy of the main shaft.


TKW's comprehensive assortment of super precision bearings is designed for machine tool spindles and other applications that require a high level of running accuracy at high to extremely high speeds. Each bearing type incorporates unique features to make it suit- able for specific operating conditions. For details about the different bearing types, refer to the relevant product chapter.


Angular contact ball bearings

high-capacity (D design)

high-speed (E design)

high-speed (B design)


all designs in different variants:

– for single mounting or matched bearing sets

– for universal matching or universally matchable sets

– bearings with steel balls or hybrid bearings

– open or with seals


Cylindrical roller bearings

single row (N design)

– basic design

– high-speed designs

– hybrid bearings double row (NN design)

– bearings with steel rollers

– hybrid bearings

double row (NNU design)


Double direction angular contact thrust ball bearings

basic design (BTW series)

– bearings with steel balls

– hybrid bearings

high-speed design (BTM series)

– bearings with steel balls


Axial-radial cylindrical roller bearings

basic design (NRT series)


Angular contact thrust ball bearings for screw drives

single direction (BSA and BSD series) universally matchable for mounting as sets

– bearings with seals

double direction with seals (BEAS series)

– for bolt mounting (BEAM series) cartridge units with a flanged housing (FBSA series)

TKW Focuses On the Development and Manufacturing of General and Non-Standard Rolling bearings
 

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