Precision Bearing
30Pages

TUNG PEI INDUSTRIAL CO., LTD CAT. NO. 2260/TE Although care has been taken to assure the accuracy of the data compiled in this catalog, TPI does not assume any liability to any company or person for errors or omissions.

1. High Precision Bearing Structure and Arrangement 1.1 Bearing Arrangement for Main Spindles Typical examples of bearing arrangements for main spindles of machine tools are summarized in Table 1.1. An optimal bearing arrangement must be determined through considerations about the properties required of the main spindle in question (maximum speed, radial and axial rigidities, main spindle size, required accuracies, lubrication system, etc.). Recently, an increasing number of new machine tool models incorporate built-in motor type main spindles. However, heat generation on a built-in motor...

Table 1.2 Tolerance of P4 and P4X Accuracy Tolerance of bore diameter of inner ring unit:μm Bore diameter P4 P4X (mm) Over Incl High Low High Low 30 If these combined bearings are used as part of multiple combined bearings, it is recommended that the variation of bore and outer diameter tolerance is within 1/3 of tolerance range. TPI bearings with special accuracy P4X can accommodate small variations of bore and outer diameter tolerance. P4X bearings have the same running accuracy as P4 while has a narrower tolerance range. It is suitable for random matching on universal combination...

Ball material Bearing type Diameter symbol Bore number Contact angle Cage symbol Bearing arrangement Flush grinding SI3N4 (Ceramic ball) SUJ2 (Steel ball) Single-row angular contact ball bearing High speed angular contact ball bearing High speed Thrust angular contact thrust ball bearing Ball screw support bearing Table 2.2 Number and code arrangement for double-row cylindrical roller bearings Dimension Symbol Radial Clearance Bore Number Tapered Bore Symbol Bearing type BS Shown (I.D.)(O.D.) Dimension symbol Bore number 15° 18° 25° 30° 40° 60° Phenolic machined cage Engineering plastic...

3 Bearing Tolerance and Fits Table 2.3 Comparison Table of TPI bearings with other brand bearings Code Brand Ball material Standard type ACBB 3.1 Bearing Tolerance Bearing “tolerances” or dimensional accuracy and running accuracy are regulated by ISO 492:2002 and JIS B 1514 standards (rolling bearing tolerances) shown in Table 3.1. When mounting a bearing to a shaft or housing, the dimensional accuracy is crucial in satisfying the tolerance. A permissible run-out occurring when rotating a bearing by one revolution is defined by the running accuracy. Appendix III shows bearing accuracy for...

Table 3.2 Measuring methods for running accuracies Running accuracy Kia = Inner ring radial runout Kea = Outer ring radial runout Sd = Inner ring side runout with bore SD = Outer ring outside surface inclination Sia = Inner ring axial runout Measurement principle A super-precision bearing that conforms to the user's main spindle specifications must be chosen in order to attain a higher level of running accuracy required of a main spindle of machine tool. A super-precision bearing of JIS accuracy class 5, 4, or 2 is usually selected according to its application. The main spindle's running...

Table 3.6 Allowable critical-value of bearing chamfer Radial bearings rs(max) or r1s (min) Table 3.5 Form accuracy of housing Precision Rolling Bearings Table 3.7 Fillet radius and abutment height Housing bore diameter (mm) Table 3.4 Form accuracy of spindle

3.3 Shaft and Housing Fits The performance of bearings such as speed capability and running accuracy is influenced by the seats and the precision of the selected fits of shaft and housing. Recommended fits for general operating conditions at inner ring rotation of precision bearings used for machine tools are shown in Tables 3.9, 3.10 and 3.11. If the dmN value (dmn: pitch circle diameter across rolling elements [mm] multiplied by speed [min-1]) is higher than the value of one million, one should consider the expansion of inner ring caused by centrifugal force. It also influences preload in...

double-row angular contact ball bearing. For two or more similar such bearings mounted side by side in a tandem arrangement, the basic dynamic radial load rating is the number of bearings to the power of 0.7 times the rating of one single-row bearing. the weaker of the inner or outer raceway contacts occurring at the position of the maximum loaded rolling element. For ball bearings, the maximum applied load value for contact stress occurring at the rolling element and raceway contact points are 4200MPa or 428kgf/mm2. 4.2 Correction factor of Bearing Life A sufficient safety factor to protect...

Fr : pure radial load (kgf) Fa : pure axial load (kgf) α : contact angle (degrees) 5.3 Rigidity of Angular Contact Ball Bearing Elastic deformation in rolling bearings results in the rings being displaced relative to each other. For angular contact ball bearings, the following formula is used to calculate this relative displacement in a radial and axial direction: Ra = q1 • Rao where, q1 : rigidity factor for bearing arrangement, please refer to Table 5.2 q2 : rigidity factor for contact angle and preload, please refer to Table 5.3 Rao : rigidity factor, please refer to Table 5.6 Table 5.2...

Table 5-5(2) Preload and Rigidity (DB and DF Arrangement) of 70AD standard series Table 5-5 (4) Preload and Rigidity (DB and DF Arrangement) of 72C standard series Bearing Preload、Rigidity、and Measured Face Side Offset Bearing Number Bearing Preload、Rigidity、and Measured Face Side Offset Bearing Number (70 series AD angle:25°nominal contact angle, steel ball) (72 series C angle:15°nominal contact angle, steel ball) Table 5-5 (3) Preload and Rigidity (DB and DF Arrangement) of 70 A standard series Table 5-5 (5) Preload and Rigidity (DB and DF Arrangement) of HSCE1 standard series Bearing...

Table 5-5 (6) Preload and Rigidity (DB and DF Arrangement) of 5S1-70C standard series Table 5-6(1) Preload and Rigidity of 70A standard series Bearing Preload、Rigidity、and Measured Face Side Offset Bearing Number (5S1-70 series C angle:15°nominal contact angle, ceramic ball) Table 5-5 (7) Preload and Rigidity (DB and DF Arrangement) of 5S1-HSCE1 standard series Bearing Preload、Rigidity、and Measured Face Side Offset Bearing Number (5S1-HS series CE1 angle:18°nominal contact angle, ceramic ball) 22 Precision Rolling Bearings 6 Bearing Lubrication The purpose of bearing lubrication is to...