PRE-TENSIONED ROLLING ELEMENT MOUNTING

Abstract

A pre-tensioned bearing assembly, including: a first rolling bearing including a first outer ring, first inner ring including a first conical surface, and a plurality of rolling elements radially disposed between the first inner and outer rings; a second rolling bearing including a second outer ring, a second inner ring including a second conical surface, and a plurality of rolling elements radially disposed between the second inner and outer rings; a shaft including a shoulder in contact with the second rolling bearing; a first conically-shaped sleeve in contact with the first conical surface and the second conical surface, and including a cylindrical inner surface; a second conically-shaped sleeve in contact with the cylindrical inner surface; and a shaft nut including an internal thread in cooperation with the shaft, and fixing the first inner ring and the second inner ring axially onto the shaft.

Claims

1-10. (canceled)

11. A pre-tensioned bearing assembly, comprising: a first rolling bearing including: a first outer ring; a first inner ring including a first conical surface defining a first bore; and, a first plurality of rolling elements radially disposed between the first inner ring and the first outer ring; a shaft penetrating the first bore and including a shoulder in contact with the first rolling bearing; a first conically-shaped sleeve: penetrating the first bore; and, in contact with the first conical surface; and, a shaft nut: including an internal thread in cooperation with the shaft; and, fixing the first inner ring onto the shaft.

12. The pre-tensioned bearing assembly of claim 11, wherein the first conically-shaped sleeve includes a conically formed inner surface, the pre-tensioned bearing assembly further comprising: a second conically-shaped sleeve: including a conical outer casing in contact with the conically formed inner surface; and, defining a second bore.

13. The pre-tensioned bearing assembly of claim 12, wherein: the second conically-shaped sleeve includes a collar extending radially outwardly; and, the second bore passes axially through the collar.

14. The pre-tensioned bearing assembly of claim 12, wherein: the second conically-shaped sleeve includes: a conical outer casing; and, a collar extending radially outwardly from the conical outer casing; and, the second bore passes axially through the collar.

15. The pre-tensioned bearing assembly of claim 12, wherein the shaft nut includes a third bore aligned with the second bore parallel to an axis of rotation of the pre-tensioned bearing assembly.

16. The pre-tensioned bearing assembly of claim 12, wherein: the second conically-shaped sleeve includes: a conical outer casing; a cylindrical inner casing; and, the second conically-shaped sleeve defines at least one recess in the conical outer casing or in the cylindrical inner casing.

17. The pre-tensioned bearing assembly of claim 11, wherein the first conically-shaped sleeve includes a cylindrical outer casing in contact with the first conical surface.

18. The pre-tensioned bearing assembly of claim 11, wherein: the first conically-shaped sleeve includes a conically formed inner surface; the conically formed inner surface defines at least one channel; and, the first conically-shaped sleeve: includes a cylindrical outer casing; and, defines at least one second bore connecting the cylindrical outer casing to the at least one channel.

19. The pre-tensioned bearing assembly of claim 11, wherein the first conically-shaped sleeve defines a slot running completely through the first conically-shaped sleeve in an axial direction and in a radial direction.

20. The pre-tensioned bearing assembly of claim 11, further comprising: a second rolling bearing including: a second outer ring; a second inner ring including a second conical surface defining a second bore; and, a second plurality of rolling elements radially disposed between the second inner ring and the second outer ring; and, a second conically-shaped sleeve including a conical outer casing, wherein: the first conically-shaped sleeve includes: a conically formed inner surface in contact with the conical outer casing; and, a cylindrical outer casing in contact with the second conical surface; and, the shaft nut fixes the second inner ring axially onto the shaft.

21. A pre-tensioned bearing assembly, comprising: a first rolling bearing including: a first outer ring; a first inner ring including a first conical surface defining a first bore; and, a first plurality of rolling elements radially disposed between the first inner ring and the first outer ring; a second rolling bearing including: a second outer ring; a second inner ring including a second conical surface defining a second bore; and, a second plurality of rolling elements radially disposed between the second inner ring and the second outer ring; a shaft including a shoulder in contact with the second rolling bearing; a first conically-shaped sleeve: in contact with the first conical surface and the second conical surface; and, including a conically formed inner surface; a second conically-shaped sleeve in contact with the conically formed inner surface; and, a shaft nut: including an internal thread in cooperation with the shaft; and, fixing the first inner ring and the second inner ring axially onto the shaft.

22. The pre-tensioned bearing assembly of claim 21, wherein the second conically-shaped sleeve includes: a conical outer casing; a collar extending radially outwardly from the conical outer casing; and, a third bore passing axially through the collar.

23. The pre-tensioned bearing assembly of claim 22, wherein the shaft nut includes a fourth bore aligned with the third bore parallel to an axis of rotation of the pre-tensioned bearing assembly.

24. The pre-tensioned bearing assembly of claim 21, wherein: the second conically-shaped sleeve includes: a conical outer casing; and, a collar extending radially outwardly from the conical outer casing; and, the shaft nut is in contact with the collar.

25. The pre-tensioned bearing assembly of claim 21, wherein: the second conically-shaped sleeve includes: a conical outer casing; and, a cylindrical inner casing; and, the second conically-shaped sleeve defines at least one recess in the conical outer casing or in the cylindrical inner casing.

26. The pre-tensioned bearing assembly of claim 21, wherein the first conically-shaped sleeve includes a cylindrical outer casing in contact with the first conical surface and with the second conical surface.

27. The pre-tensioned bearing assembly of claim 21, wherein the first conically-shaped sleeve: includes a conically formed inner surface; defines at least one channel in the conically formed inner surface; includes a cylindrical outer casing; and, defines at least one third bore connecting the cylindrical outer casing to the at least one channel.

28. A method of assembling a pre-tensioned bearing assembly including a first rolling bearing with a first inner ring including a first conical surface defining a first bore, a second rolling bearing including a second inner ring including a second conical surface defining a second bore, a shaft including a shoulder, a first conically-shaped sleeve, a second conically-shaped sleeve, and a shaft nut, the method comprising: fitting the first rolling bearing and the second rolling bearing on the shaft such that the second rolling bearing contacts the shoulder; inserting the first conically-shaped sleeve around the shaft and through the first bore and through the second bore; contacting the first conical surface and the second conical surface with a cylindrical outer casing of the first conically-shaped sleeve; inserting the second conically-shaped sleeve into a space defined by the shaft and a conically formed inner surface of the first conically-shaped sleeve, the space radially increasing in a first axial direction parallel to an axis of rotation of the pre-tensioned bearing assembly; displacing, in a second axial direction, opposite the first axial direction, the shaft nut along the shaft; displacing, with the shaft nut, the first conically-shaped sleeve in the second axial direction; contacting the first inner ring with a flange of the first conically-shaped sleeve; urging, with the first conically-shaped sleeve, the second rolling bearing against the shoulder of the shaft; screwing a feed screw through a threaded axial bore in the shaft nut and into contact with a collar of the second conically-shaped sleeve; and, displacing, with the feed screw, the second conically-shaped sleeve, with respect to the first conically-shaped sleeve, in the second axial direction.

29. The method of claim 28, wherein displacing, with the feed screw, the second conically-shaped sleeve, with respect to the first conically-shaped sleeve, in the second axial direction includes: expanding the cylindrical outer casing of the first conically-shaped sleeve radially outwardly; and, urging, with the cylindrical outer casing of the first conically-shaped sleeve, the first inner ring and the second inner ring radially outwardly.

30. The method of claim 28, wherein displacing, with the feed screw, the first conically-shaped sleeve, with respect to the second conically-shaped sleeve, in the second axial direction includes: pressing oil through a bore defined by the first conically-shaped sleeve and into the space defined by the shaft and the conically formed inner surface; and, urging, with the oil, the first conically-shaped sleeve radially outwardly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which:

[0017] FIG. 1 shows a rolling element bearing,

[0018] FIG. 2 shows a second sleeve,

[0019] FIG. 3 shows a first sleeve,

[0020] FIG. 4 shows a shaft nut,

[0021] FIG. 5 shows an assembly illustration,

[0022] FIG. 6 shows a disassembly illustration, and

[0023] FIG. 7 shows a detail of inner ring and shaft

DETAILED DESCRIPTION

[0024] In FIG. 1, a rolling element bearing is shown. In this exemplary embodiment, this rolling element bearing is formed by two rolling bearings 1.1 and 1.2 and, in another exemplary embodiment, also comprises only one of rolling bearings 1.1 or 1.2. Each of rolling bearings 1.1 and 1.2 is formed by inner ring 2, outer ring 3, coaxially surrounding inner ring 2, and rolling elements 4. Rolling elements 4 are radially disposed between ring 2 and ring 3, and roll on raceways 5 provided by inner ring 2 and outer ring 3 between respective bearing rings 2 and 3. Inner ring 2 of bearing 1.1 defines bore 7. Inner ring 2 of bearing 1.2 defines bore 7.

[0025] Furthermore, shaft 6 is shown in FIG. 1, which penetrates bore 7 of each of inner rings 2 when rolling bearings 1.1 and 1.2. are mounted on shaft 6. Shaft 6 is provided with a first fixing means, which is formed by shaft shoulder 8 provided in one piece with shaft 6. When rolling bearings 1.1 and 1.2 are mounted on shaft 6, rolling bearings 1.1 and 1.2 are axially unseparated from one another, with rolling bearing 1.2 being supported on shaft shoulder 8 through physical contact.

[0026] Conically-shaped sleeve 9, in this exemplary embodiment, has cylindrical outer casing 10 and is inserted into cylindrical bores 7 of inner rings 2 when rolling bearings 1.1 and 1.2 are mounted on shaft 6. Inner surface 11 of sleeve 9 is formed conically. As can be seen in FIG. 2, which shows sleeve 9 on an enlarged scale, sleeve 9 is provided with oil pressure bore 18.1 which can be connected to a hydraulic unit, not shown. Oil pressure bore 18.1 feeds radially inwardly open channels 19 provided on inner surface 11 of sleeve 9. To facilitate insertion of sleeve 9 into bore 7 of inner rings 2, sleeve 9 defines slot 20, which completely passes through sleeve 9 axially and radially and therefore reduces the diameter of sleeve 9 elastically somewhat during insertion of sleeve 9 into bore 7.

[0027] Conically-shaped sleeve 12 has conical outer casing 13 and radially outwardly directed collar 14 (FIG. 3). Three threaded axial bores 15.1 are defined by collar 14. In addition, conical outer casing 13 and cylindrical inner casing 16 of sleeve 12 define trough-shaped recesses 17 to increase lability and compressibility of sleeve 12, and which extend in the direction of the longitudinal axis of sleeve 12, but without breaking through sleeve body 18 of sleeve 12.

[0028] FIG. 1 also shows a further fixing means, which in the present case is formed by shaft nut 21. When rolling bearings 1.1 and 1.2 are fitted onto shaft 6 so that rolling bearing 1.2 rests against shaft shoulder 8, and sleeves 9 and 12 are arranged between inner rings 2 and shaft 6, inner rings 2 fix rolling bearings 1.1 and 1.2 axially on shaft 6 by tightening shaft nut 21. For this purpose, as shown in FIG. 4, shaft nut 21 is provided with internal thread 22, which cooperates in a known manner with an external thread (not shown) on shaft 6. In addition, axial bores 15.2, 15.3 and 15.4 and radial bores 23.1 and 23.2 are defined by shaft nut 21 (FIG. 4). Rods can be inserted into radial bores 23.1 and 23.2 (as indicated for radial bore 23.1) to rotate shaft nut 21 relative to shaft 6. Axial bores 15.2 lie on partial diameter D1, which is smaller than pitch circle diameter D2 on which axial bores 15.3 lie. Furthermore, annular groove 24 is introduced from the inside of shaft nut 21, which extends in the circumferential direction and reaches almost to the outer circumference of shaft nut 21 (indicated by the dashed lines). Annular groove 24 is penetrated by axial bore 15.4. When shaft nut 21 is screwed onto shaft 6 and when a screw (not shown) is screwed into axial bore 15.4, the axial width of annular groove 24 changes somewhat, as a result of which the threads of internal thread 22 of shaft nut 21 are pressed against the threads of shaft 6 in a known manner to achieve screw locking.

[0029] The assembly of a pre-tensioned rolling element bearing will now be explained with reference to FIG. 5. For this purpose, two rolling bearings 1.1 and 1.2 are already fitted back-to-back onto shaft 6 so that inner ring 2 of rolling bearing 1.2 rests on shaft shoulder 8 of shaft 6. Bore 7 of inner rings 2 is borne down on by sleeve 9, inner surface 11 of which maintains small radial spacing A from shaft 6. Since inner surface 11 of sleeve 9 is formed conically, radial spacing A increases starting from the end near shaft shoulder 8 to the end remote from shaft shoulder 8. Furthermore, sleeve 9 is provided at the end remote from shaft shoulder 8 with radially outwardly directed flange 25 which, in the assembled state, rests on inner ring 2 of rolling bearing 1.1. Sleeve 12 is inserted into radial spacing A, cylindrical inner casing 16 thereof surrounding shaft 6 and conical outer casing 13 thereof extending complementarily to inner surface 11 of sleeve 9 and thus engages somewhat in radial spacing A.

[0030] Rolling bearings 1.1 and 1.2 are also ultimately axially fixed by screwing shaft nut 21 onto shaft 6, in that inner rings 2 are pressed against shaft shoulder 8 by shaft nut 21 through intermediary of flange 25.

[0031] Feed screws 26 are then screwed into threaded axial bores 15.2 of shaft nut 21, which then meet collar 14 of sleeve 12 and displace sleeve 12 in the direction of arrow P1 relative to sleeve 9, thereby forming the interference fit required for the pre-tensioning of rolling bearings 1.1 and 1.2. That is, displacing sleeve 12 in the direction of arrow P1 relative to sleeve 9 expands sleeve 9 and cylindrical outer casing 10 radially outwardly so that casing 10 urges races 2 radially outwardly.

[0032] The tightening of feed screws 26 or movement of sleeve 12 relative to sleeve 9 takes place under oil pressure. For this purpose, oil pressure bore 18.1 on sleeve 9 is connected to hydraulic unit 30, oil is pressed into channels 19 (FIG. 2) of sleeve 9, and radial spacing A between shaft 6 and sleeve 9 is increased somewhat so as to facilitate the insertion of sleeve 12 into sleeve 9. As can be taken from FIG. 5, shaft 6 is also provided with oil pressure bore 18.2 which, like oil pressure bore 18.1, is connected to hydraulic unit 30 during assembly and thus likewise presses oil in the area between shaft nut 21 and shaft shoulder 8.

[0033] The axial movement of sleeve 12 with respect to sleeve 9 is recorded by dial gauge 27 which is fixed in axial bore 15.3 and is in operative connection with collar 14 of first sleeve 12.

[0034] The disassembly of a pre-tensioned rolling element bearing will now be explained with reference to FIG. 6. For this purpose, the screw locking of shaft nut 21 is first removed and shaft shafts 21 loosened so far that the bore centers of axial bores 15.3 are aligned with the bore centers of axial bores 15.1 in collar 14 of sleeve 12. When feed screws 26 are left in axial bores 15.2 of shaft nut 21 after assembly, which can be advantageous for axially supporting sleeve 12, feed screws 26 must of course be loosened or removed before shaft nut 21 is loosened. Releasing screws 28 are then inserted into axial bores 15.3, which are designed only as through-bores, and screwed into threaded axial bores 15.1 of sleeve 12. When screw heads 29 of releasing screws 28 come into contact with shaft nut 21, releasing screws 28 pull sleeve 12 somewhat out of radial spacing A between sleeve 9 and shaft 6 in the direction of arrow P2, whereby the interference fit is canceled, rolling bearings 1.1, 1.2 lie loosely on shaft 6 and, after shaft nut 21 has been completely removed, can be pulled off shaft 6 easily and without any additional force. As already explained in connection with FIG. 5, disassembly is also advantageously carried out under oil pressure, in that respective oil pressure bores 18.1, 18.2 are connected to hydraulic unit 30.

[0035] Special releasing screws 28 need not be provided, but feed screws 26 can also be used for disassembly if thread-free axial bores 15.3 have a slightly larger diameter than threaded axial bores 15.2, so that screws used as feed screws 26 and now serving as releasing screws 28 can be freely inserted through thread-free axial bores 15.3.

[0036] So as not to weaken the strength of shaft nut 21 through many axial bores 15.2, 15.3 arranged on two pitch circles, a pitch circle with axial bores can be dispensed with in another embodiment—not shown further. In this case, threaded axial bores 15.2 arranged only on partial diameter D1 are used not only as threaded bores for feed screws 26, but at the same time also as mere through-bores for receiving releasing screws 28. To achieve this, however, it goes without saying that separate releasing screws 28 must be used, the diameter of which is smaller than that of feed screws 26, so that release screws 28 here can also be freely inserted through axial bores 15.2.

[0037] So far it has been assumed that surface 11, which interacts with conical outer casing 13 of sleeve 12, is provided by sleeve 9. As FIG. 7 shows, which shows only a section similar to the detailed drawing according to FIG. 5, surface 11 can also be provided directly on inner rings 2, which then slightly increases the machining effort due to the conicity of bores 7 in inner rings 2. Surface 11 formed directly on inner rings 2 then interacts with likewise conical outer casing 13 of sleeve 12 to produce an interference fit.

LIST OF REFERENCE SYMBOLS

[0038] 1.1, 1.2 Rolling bearing [0039] 2 Inner ring [0040] 3 Outer ring [0041] 4 Rolling element [0042] 5 Raceway [0043] 6 Shaft [0044] 7 Bore [0045] 8 Shaft shoulder [0046] 9 Second sleeve [0047] 10 Cylindrical outer casing [0048] 11 Inner surface [0049] 12 First sleeve [0050] 13 Conical outer casing [0051] 14 Collar [0052] 15.1, 15.2, 15.n Axial bore [0053] 16 Cylindrical inner casing [0054] 17 Recesses [0055] 18.1; 18.2 Oil pressure bore [0056] 19 Channel [0057] 20 Slot [0058] 21 Shaft nut [0059] 22 Internal thread [0060] 23 Radial bores [0061] 24 Annular groove [0062] 25 Flange [0063] 26 Feed screws [0064] 27 Dial indicator [0065] 28 Releasing screws [0066] 29 Screw head [0067] 30 Hydraulic unit