Ball screw bearings series, shorten as BS bearings, is designed to maximize smaller ball numbers with thicker I/R & O/R and 60 degree contact angle. This design allows BS bearings have greater axial rigidity than any other TPI angular contact bearing series like standard ball bearings. HBS bearing is designed to accommodate heavy load applications, such as plastic injection molding machines. Compare to BS bearings series, HBS bearing provides relatively higher load rating and stiffness.
Carbonitriding on both inner and outer rings is a basic hardening process for TPI BS bearings. Through this special heat treatment, hardness on the raceway surface is increased; which reduces wear accordingly.
High precision steel balls ensure TPI ball bearings suppliers' BS bearings and HBS bearing have the best precision and stability. This also reflects in BS bearings performance under high speed rotation.
With the highly engineered arrangement of cages, remarkable characteristics were achieved.
T2 cage, desinged for low noise level, however, the temperature rise in high RPM is relatively high.
Seal
Contact seal, prevent dust and liquid contamination from getting into BS bearings. However, the torque will be higher and the limiting speeds will be lower under such application.
The non-contact seal provides general protection for BS bearings. It cannot prevent liquid contamination from getting into BS bearings. Torque and limiting speeds are the same as the open type.
TPI two wheeler bearings supplier cooperates with the best grease manufacturers in the world which allows us to suggest and apply the best lubricating selection for our customer.
Bearing life is usually expressed as the number of hours an individual bearing will operate before material fatigue develops on either the raceways or the rolling element. The usual life rating for industrial applications is called “L10” life. The L10 life is the number of hours which that 90% of bearings will survive; or, conversely, 10% of bearings will have failed in the L10 number of service hours.
System rigidity, one of the main factors of productivity and accuracy when it comes to machine tools and other precision applications. By preloading the bearings, it becomes extremely rigid and the magnitude of elastic deformation becomes neglectable.
BS bearings and HBS bearing in duplex arrangements vary in combinations of two, three, or four, in accordance with the user's required specifications. Back-to-back duplex (DB) arrangement and face-to-face duplex (DF) arrangement can both sustain radial and axial loads in both directions. The wider distance between the effective load centers of the DB arrangement allows larger moment loads to be handled.
The designation indicates the form, size, precision, internal structure, etc. of the bearing, and it's shown as below:
Ball material
Blank
SUJ2 (Steel ball)
Bearing series
BS
Ball screw support bearing (Contact angle 60°)
Bore and outer diameter number
1747 - 100215
Shown (I.D.)mm (O.D.)mm
Matching code
DB
Back to back arrangement
DF
Face to face arrangement
DT
Tandem arrangement
DBT
Tandem and back to back (triple-row)
DTBT
Tandem and back to back (quad-row)
Flush grinding
G
Flush ground type
Blank
Without flush ground
Preload codes
GL
Light preload
GN
Normal preload
GM
Medium preload
Accuracy
P4
JIS standard class 4
UP
JIS standard UP
P4A
JIS standard class 4, Special bore and outside diameter tolerance
Seal
Sealing type
Bearing with seals on both sides to prevent contamination getting in and bearing grease getting out.
Grease
Code
Thickener
Base oil
Dropping point (℃)
NLGI
Operating temperature range (℃)
Characteristics
Application
1
1K
Li
Ester+ SHC
190
2
-55~+130
General used, low torque
High speed spindle
2
12K
Li
Ester
≧200
2
-50~+150
Low torque
High speed ball screw support
3
15K
Ba Complex
Mineral
≧200
2
-40~+130
Low torque
High speed spindle
4
L559
Li
Ester
≧250
2
-40~+150
Anti-oxidation, long-life
High speed spindle
5
L588
Urea
Mineral
230
2
-40~+120
Anti-fretting
Low speed ball screw support
6
2AS
Li
Mineral
181
2
-25~+120
General used
Low speed ball screw support
7
L712
Polyurea
Ester+ SHC
≧220
2
-50~+120
Low torque high speed
High speed spindle
8
L433
Polyurea
Ester+ SHC
≧250
3
-40~+160
High speed, low noise
High speed motor
9
L700
Urea
Ester+ SHC
260
2
-20~+160
Wear resistance, anti-oxidation
High speed servo motor
10
L135
Ba Complex
Mineral
≧220
2
-20~+140
Wear resistance, Heavy loading (EP)
Ball screw support
Preload / Rigidity
Rigidity of Spindle
System rigidity in machine tool applications is extremely important because the magnitude of deflection under load determines machining accuracy. Bearing rigidity is only one factor that influences system rigidity; others include shaft diameter, tool overhang, housing rigidity number, position and type of bearings. For axial rigidity of spindles, bearing rigidity plays an important role of it. Giving preload to a bearing result in the rolling element and raceway surfaces being under constant elastic compressive forces at their contact points. This has the effect of making the bearing extremely rigid so that even when load is applied to the bearing, radial or axial shaft displacement does not occur. If high radial rigidity of bearing is needed, cylindrical roller bearings are normally used. In contrast to angular contact ball bearing, they provide more surface contact and gross sliding and are not suitable for very high-speed applications. For axial loading applications, angular contact ball bearings are normally used. Their larger contact angle type provides higher axial rigidity. The rigidity of this type also depends on number and size of balls. Recently, the ceramic material silicon nitride Si3N4 is used for precision ball bearings. The radial rigidity of this hybrid bearing is approximately 15% higher because of the higher Young's modulus. As mentioned in 4.5, TPI's HS type angular contact ball bearings are optimally designed with their internal configuration to accommodate both low-ball skidding effect and high rigidity by using TH-BBAN.
Bearing Preload
The preload method is divided into fixed position preload and constant pressure preload as shown in Fig. 5.1. The fixed position preload is effective for positioning the two bearings and also for increasing the rigidity. Due to the use of a spring for the constant pressure preload, the preloading amount can be kept constant, even when the distance between the two bearings fluctuates under the influence of operating heat and load.
The increased rigidity effect preloading has on bearings is shown in Fig. 5.2. When the offset inner rings of the two paired angular contact ball bearings are pressed together, each inner ring is displaced axially by the amount δao and is thus given a preload, Fao, in the direction. Under this condition, when external axial load Fa is applied, bearing A will have an increased displacement by the amountδao and bearing B's displacement will decrease. At this time the loads applied to bearing A and B are FaA and FaB, respectively. Under the condition of no preload, bearing A will be displaced by the amount δaoA when axial load Fa is applied. Since the amount of displacement, δa, is less than δaoA, it indicates a higher rigidity for δa. When external axial load Fa keeps increasing until δaA equals to 2δaoA, that is δaB=0. Now, bearing B becomes released from preload while bearing A is loaded with 2.83 times of given preload Fao. This amount of load is called the limiting axial load and it may depend on bearing arrangement and contact angle.
Arrangement
Duplex Arrangement Bearings
As Fig. 1.1 shows, angular contact ball bearings in duplex arrangements vary in combinations of two, three or four, in accordance to user's required specifications. Back-to-back duplex (DB) arrangement and face-to-face duplex (DF) arrangement can both sustain radial and axial loads in both directions. The wider distance between the effective load centers of the DB arrangement allows larger moment loads to be handled. The main spindle in machine tools often uses this arrangement. Compared with the DB arrangement, the DF arrangement has shorter distance between the effective load centers, therefore the capacity to handle moment loads is small. However, it possesses greater allowable inclination angle than the DB arrangement. The tandem duplex (DT) arrangement is able to handle both radial load and large axial load, but only in one direction. The four-row duplex (DTBT) arrangement is commonly used for the main spindles of machining centers because it offers high rigidity and accommodates high-speed operation.
Marking of Bearings and Bearing Sets
A “<”shaped marking on the outside surface of the outer rings of matched bearing sets indicates how the bearings should be mounted to obtain the proper preload in the set. The marking also indicates how the bearing set should be mounted in relation to the axial load. The ”<” should point in the direction in which the axial load will act on the inner ring. In applications where there are axial loads in both directions, the ”<” should point toward the greater of the two loads, refer to Fig. 1.2。 For universal combination bearings, the ”<” marking on the outside surface of the outer rings shown in Fig. 1.3, prevent “direction” mistakes, ensure correct matching when they are mounted.
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