WO1994028325A1

WO1994028325A1 - An arrangement for attaching ball bearings, roller bearings, gears, belt sheavers or the like onto shafts

Info

Publication number: WO1994028325A1
Application number: PCT/NO1993/000096
Authority: WO
Inventors: Harald Kolvereid
Original assignee: Harald Kolvereid
Priority date: 1993-05-19
Filing date: 1993-06-29
Publication date: 1994-12-08
Also published as: NO931836D0; JPH08510538A; EP0706618A1; AU4590193A

Abstract

An arrangement for preventing axial travel of a sleeve that secures clamps a functional member, e.g. a bearing (1) onto a rotating shaft (10), the sleeve consisting of two concentric, cylindrical parts - an inner part (15) having threads on the outside and an outer (16) with corresponding threads on the inside -, coacting stop means (27), and wrench grip. Beads (17, 18; 25, 26) are located on the inside and outside of the sleeve. The thread faces (20, 24; 31, 32) of the sleeve are limited to obtain continuous loading at two circular zones on the sleeve parts. One half of the inner part (29) may have an external right-hand thread and the other half left-hand thread. The outer part (30) will internally have corresponding threads, respectively. Both sleeve parts (15, 16; 29, 30) have slot means (44, 45).

Description

AN ARRANGEMENT FOR ATTACHING BALL BEARINGS, ROLLER BEARINGS, GEARS, BELT SHEAVERS OR THE LIKE ONTO SHAFTS.

The present invention relates to an arrangement for prevent¬ ing axial travel of a sleeve that secure clamps a functional member — e.g., ball bearing, roller bearing, gear, fan wheel, belt sheave or the like — onto a rotating shaft, and for attaining a more favorable load condition on the inner,

10 annular portion of said functional member on rotation of a shaft that may be subjected to bending stress, and wherein said functional member is mounted on the sleeve consisting of two cylindrical sleeve parts, one outside the other, wherein the outer sleeve part has cylindrical threads on the inside ¹? thereof, and the inner sleeve part has corresponding threads on the outside thereof, and wherein both sleeve parts have a wrench grip at either the same end or opposite ends.

The most common method of attaching ball and roller bearings

20 to shafts is by heat shrinking or pressing, although conical sleeves are also used.

Most common for the fastening of gears, fan wheels, or the like to shafts is the use of a wedge and wedge slot, but

25 shrinking and mounting on a sleeve are also widely employed methods.

A double-acting sleeve which, according to CH patent 457978, Fig. 7, is based on cylindrical threads and a stop edge will, -⁵⁰ on rotation between the two members of which the sleeve consists, provide a fastening for bearings, gears, or the like to shafts. The shrinking effect occurs when the two threaded parts are screwed together to the stop position, whereafter the parts are rotated in relation to each other

35 thereby to attain a tension force between the sleeve parts and a form of mechanical shrinking. Locking is thus achieved by means of friction between, for example, the shaft and the inner ring of the bearing.

The type of bearing most often employed in industry today iε 5 the track ball bearing. It has been shown that when such a bearing is mounted on the type of sleeve described above, axial travel of the sleeve with the bearing often occurs when the mounting is done on a smooth shaft. The mounting of bearings on smooth as opposed to graduated shafts is part of ■° the objective of using sleeve mounting instead of shrinking or pressing.

The phenomenon of axial travel occurs under unequal load conditions. A sleeve having a bearing mounted over a right- .5 hand thread will during operation undergo axial movement without rotation and in the same direction as a right-handed nut that iε screwed toward the left. The situation is explained by the phenomenon popularly referred to as carpet effect.

20

Travel occurs because the load between the clamping sleeve and the shaft, generated by the clamping of the bearing and by the ball thrust, alternates from resting on the edges of the bearing and the sleeve to lying at the center of the 25 bearing and sleeve when the shaft is subjected to bending stress during rotation; see Figs. 1 and 2, which indicate the prior art.

Fig. 1 shows a section of the inner ring from a track ball ?° bearing 1, a ball race 2, a shaft 10, a double sleeve with inner sleeve 3 and outer sleeve 4, both having a smooth side and a sawtoothed thread 5 on the opposite side, stop edges 6, a special wrench grip 7, and line 8 indicating the curve in the shaft in addition to showing the single contact zone 9 on ?5 the opposite side of the load from the ballε, when the shaft is subjected to bending stress. In Fig. 2 the arrowε 11 indicate the load from the ballε, and line 12 indicateε the curve in the shaft and shows the two load areas 13 and 14 on the εleeve on the load εide when shaft 10 is subjected to bending stress. The curve of the shaft is shown highly exaggerated in Figs. 1 and 2, as well as in Figs. 3, 4 and 6, and it will be appreciated that the shaft of course does not actually extend through the end section of the sleeve, as is suggested by Figε. 2 and 4, in particular.

The load alternation over the cross section of the bearing also contributes -- in addition to the main load from the ballε -- to material fatigue in the ball race.

The axial travel is a disadvantage and imposes an unaccept¬ able limitation on the utilization of sleeves.

The present arrangement will overcome said disadvantge, and the characterizing features of the arrangement will be disclosed in the appurtenant patent claims, as well as in the following description with reference to the attached figures.

Figs. 1 and 2 show a clamping sleeve that securely attaches a ball bearing to a shaft subjected to bending forces, in accordance with the known art.

Figs. 3 and 4 show a first embodiment of the arrangement according to the invention, which secures a ball bearing to a shaft that iε subjected to bending forces.

Fig. 5 shows a second embodiment of the arrangement according to the invention.

Fig. 6 shows a third embodiment of the arrangement according to the invention, aε a modification of the arrangement in Fig. 5. Fig. 7 shows a fourth embodiment of the arrangement according to the invention.

Fig. 8 iε a plane view of a εection of an inner portion of a clamping εleeve used in the arrangement according to the invention, as illustrated in Figε. 3-7.

In the following description, the functional member iε for the sake of simplicity described as a ball bearing, although this shall in no way be regarded as limiting the application of the present invention.

An essential feature of the arrangement, according to the invention, is that the axial travel iε prevented by the creation of two axially separate zones for contact between bearing and shaft. Such zones continuously bear weight and are provided, for example, by the forming of raised sections on the inside and outside of the clamping sleeve. A corresponding effect is attained by splitting up the thread in the clamping sleeve, or these two methods may be combined. According to an alternative solution, the bearing itself may be designed with elevated sections on its inner ring in the axial direction, in addition to the use of a clamping sleeve as indicated above.

The method simultaneously reduces to a substantial degree the alternating tensions in the ball race from bending stress during rotation and therefore contributes toward prolonging the lifetime of the bearing.

Fig. 3 shows bearing ring 1 mounted on a sleeve 18 consisting of an outer sleeve part 15 and inner sleeve part 16, positioned against the curve 19 on the shaft. The contact zones have an axial expanse equal to the threaded areas 20 and 21. Areas 22, 23 and 24 indicate where material has been removed on the inner and outer side of the sleeve part, and provide marked limitations for the contact zones (the raised sectionε) 17, 18, 25 and 26. Reference numeral 28 denotes the end εtop, and 33 the wrench grip.

In Fig. 4 arrowε 11 indicate the load from the ballε in the bearing, and line 27 indicateε the two load areaε 17' and 18' (which coincide with areaε 17 and 18 in Fig. 3) on the load εide of the sleeve when shaft 10 iε subjected to bending streεε.

An end stop on the sleeves may be avoided by replacing the thread surface having a through-going right-hand thread with a thread surface wherein a right-hand and a left-hand thread are combined, as shown in Fig. 5.

Fig. 5 shows a section through the inner ring from a track ball bearing 1, ball race 2, double clamping sleeve with inner sleeve part 29, outer sleeve part 30, sawtoothed right- hand thread formed as contact zone 31 , sawtoothed left-hand thread formed as contact zone 32, and special wrench grip 33.

If the bearing is unintentionally positioned off-center to the sleeve or if during operation the bearing transmits axial forces such that the resulting load from the ball thrust falls outside the center of the sleeve, then axial travel will occur. This is counteracted by means of the marked contact zones 31 and 32, which continuously bear load.

The axial forces from the right-hand thread 31 which are generated during tightening are taken up by the left-hand thread 32, and vice-versa; thus the end stop used on sleeves having a throughgoing right- or left-hand thread, or as in Figs. 3 and 4, is superfluous.

The double-thread design also renders the sleeve more suitable for withstanding greater moment loads from oblique or conical gears, than a sleeve with a stop edge. The sleeves are mounted by being slid in axially onto each other, since they are relatively thin and flexible and the thread height is slight.

A bearing is often relatively narrow compared to the diameter of the shaft, and it is therefore desirable to secure an effective preεεure surface between the εleeve and inner ring. Thiε iε achieved by employing a sawtoothed thread having one large and one small flank angle.

For other applications the requirement for an effective pressure surface is insignificant, while it is important to obtain a locking between the sleeve parts independently of the direction in which one sleeve rotateε relative to the other. This latter objective iε attained by selecting a saw¬ toothed thread profile wherein the flank angles are equal; see Fig. 6.

Fig. 6 shows the inner ring 1 of the bearing mounted on a double clamping sleeve, with a right-hand thread formed as contact zone 34 and a left-hand thread formed as contact zone 35, wherein the flank angles in the thread are equal. As indicated for Fig. 5, both the outer sleeve 36 and the inner sleeve 37 have lowered sections 38, 39 and 40 on the thread surface side, such that thread sections 34 and 35 in the embodiment in Fig. 6 form raised sections on the outside of inner sleeve 37 and on the inner side of outer sleeve 36.

Fig. 7 shows a solution utilizing a clamping sleeve e - bodiment according to Figs. 3 and 4. It shall be appreciated, however, that clamping sleeves of the type shown in Figs. 5 and 6 may alternatively be used; or it may be unnecessary to provide the outer sleeve part with raised sectionε 25, 26. Instead, the inner ring of the bearing is provided with beadε 40, 41. This affords the attainment of as favorable a load condition aε possible on the inner ring of the bearing on rotation of shafts that are subjected to bending stress. Fig. 8 shows a planar section of an inner sleeve sector having a right-hand thread 42, left-hand thread 43 and slots 44 and 45 that do not pass completely therethrough, wherein zone 46 is designed to provide for a spring effect on compresεion of the clamping sleeve, and gradations 47 in the special wrench grip.

Shrinking effect is attained when the threaded parts are rotated relative to each other, and each threaded part must therefore be provided with a wrench grip positioned at the same end, or with one or two grips at each end. These may be hexagonal grips, hook wrench grips or special grips that come to be used depending on the specifications for adjustment moment, space considerations, precision, etc. A wrench grip particularly suited for sleeve mounting is disclosed in EPC application no. 88905005.0, Figs. 12-14.

Claims

P a t e n t C l a i m s

1.

An arrangement for preventing axial travel of a clamping sleeve that securely clamps a functional member — e.g., ball bearing, roller bearing, gear, fan wheel, belt sheave or the like -- onto a rotating shaft, and for attaining a more favorable load condition on the inner, annular portion of said functional member on rotation of a shaft that may be subjected to bending stress, and wherein said functional member is mounted on the sleeve consisting of two cylindrical sleeve parts, one outside the other, wherein the outer sleeve part has cylindrical threads on the inside thereof, and the inner sleeve part has corresponding threads on the outside thereof, and wherein both sleeve parts are provided with a wrench grip at the same end or at opposite ends, c h a r a c t e r i z e d i n that the load on the clamping sleeve from the clamping of the functional member is transmitted in two zones in the axial direction of said functional member, there being formed on the inside of the inner sleeve and, optionally, on the outside of the outer sleeve two elevations, or beads, on which said functional member and sleeve may rest, and that the thread in the clamping sleeve is limited to two areas corresponding to said elevation or beads.

2.

An arrangement as disclosed in claim 1, for attaining a more favorable load condition on the inner wing-shaped section of a functional member on rotation of shafts that are subjected to bending stress, c h a r a c t e r i z e d i n that the functional member is a bearing and that two beads are formed on the inside of the inner ring of the bearing.

3.

An arrangement as disclosed in claim 1 or 2, c h a r a c t e r i z e d i n that on the outside of the inner sleeve and the inside of the outer sleeve there are opposing threaded surfaces having a right-hand thread running from the center of the sleeve part and out toward one edge, and having a left-hand thread extending from the center and out toward a second edge, and wherein the thread profile for said right- and left-hand threads is sawtoothed with one large and one small flank angle, the axial force from the right-hand thread being taken up by the left-hand thread, and vice versa, and that said inner and outer sleeves are designed such that they may be slid in onto one another for mounting.

4.

An arrangement as disclosed in one or more of the claims 1-3, c h a r a c t e r i z e d i n that a marked area without threads is provided between the right- and left-hand threads on said inner and outer sleeve in order to create axially separated contact zones.

5.

An arrangement as disclosed in one or more of the claims 1-4, c h a r a c t e r i z e d i n that each sleeve member has a slot passing therethrough.

6.

An arrangement as disclosed in one or more of the claims 1-5, c h a r a c t e r i z e d i n that each sleeve member has a plurality of slots that do not pass therethrough.

7.

An arrangement as disclosed in one or more of the claims 1-6, c h a r a c t e r i z e d i n that the flank angles of the threads are equal .