ACBB, which is the abbreviation of angular contact ball bearings. With different contact angles, the higher axial load can be well taken care now. TPI standard ball bearings are the perfect solution for high runout accuracy applications such as machine tool main spindles.
With the highly engineered arrangement of cages, remarkable characteristics were achieved.
The non-contact seal was well designed by TPI roller bearing company to effectively reduce the external dust entering in standard ball bearings while rotating.
Selecting the most suitable grease for angular contact ball bearings requires experience and expertise. With years of experience cooperating with the best grease manufacturers, TPI is able to provide the perfect bearing with most suitable grease 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.
Standard 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 designation indicates the form, size, precision, internal structure, etc. of the bearing, and it's shown as below:
| Ball material | 5S1- | Si3N4 (Ceramic ball) |
| Blank | SUJ2 (Steel ball) | |
| Bearing type | 7 | Single-row angular contact ball bearing |
| HS | High speed angular contact ball bearing | |
| BT | High speed angular contact thrust ball bearing | |
| Diameter symbol | 9 | |
| 0 | ||
| 2 | ||
| 3 | ||
| Bore number | 6 - 26 | below number 03 00: 10mm 01: 12mm 02: 15mm 03: 17mm above number 04 bore number x5 mm |
| Contact angle | C | 15° |
| CE1 | 18° | |
| AD | 25° | |
| A | 30° | |
| B | 40° | |
| Cage symbol | T1 | Phenolic machined cage |
| T2 | Engineering plastic molded cage | |
| T3 | Engineering plastic molded cage | |
| Bearing arrangement | 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 | GL | Light preload |
| GN | Normal preload | |
| GM | Medium preload | |
| GH | Heavy preload | |
| GXX | Special preload | |
| Accuracy | P5 | JIS standard class 5 |
| P4 | JIS standard class 4 | |
| P4X | JIS standard class 4, Special bore and outside diameter tolerance | |
| P42 | JIS standard class 4 (dimensional)、 JIS standard class 2 (running accuracy) | |
| P2 | JIS standard class 2 |
Bearing with seals on both sides to prevent contamination getting in and bearing grease getting out.
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.
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.
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.
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.
