GB2112085A

GB2112085A - A single-row or double-row rolling bearing

Info

Publication number: GB2112085A
Application number: GB08236139A
Authority: GB
Inventors: Heinrich Hofman; Gunther Markfelder
Original assignee: FAG Kugelfischer Georg Schaefer KGaA; Kugelfischer Georg Schaefer and Co
Current assignee: IHO Holding GmbH and Co KG
Priority date: 1981-12-21
Filing date: 1982-12-20
Publication date: 1983-07-13
Also published as: FR2518675A1; JPS58134222A; DE3150605A1; FR2518675B3; IT1153360B; IT8224604A0; IT8224604A1; SE8206995D0; DE3150605C2; SE8206995L

Abstract

A single-row or double-row rolling bearing comprises a rimless inner race 8, a rimless outer race 7 and rollers 9. In order to ensure a high radial and axial load capacity of the bearing, to facilitate mass-production of the rollers and to reduce friction resulting from a sliding instead of the desired rolling motion of the rollers, at least the regions adjacent the two end faces 6 of each roller are curved along their longitudinal extent. Alternatively, each roller may be curved convexly with the same radius along its entire length. Whatever roller is used, the, or each, centre 11 of the, or each, curvature is disposed on the opposite side of the bearing axis 10 and the smallest radius 12 of the, or each, curvature is greater than ten times the length of the roller. The shape of the tracks of the inner and outer races is substantially the same as that of the rollers. <IMAGE>

Description

SPECIFICATION A single-row or double-row taper-rolling bearing This invention relates to a single-row or double row taper-rolling bearing comprising a rimless inner race, a rimless outer race, rollers and a cage.

Taper-rolling bearings fitted with cylindrical rollers are generally known. A disadvantage of these bearings is, however, that in view of the axial load acting on the rollers they must always be provided with guide shoulders or rims. This is unsatisfactory both as regards their manufacture and operation, the reason being that, on the one hand, grinding of the tracks is rendered more difficult and, on the other hand, the friction at the contact faces between the roller end faces and the shoulders is increased, thus causing the bearings to be further heated. A solution presenting itself is to replace these constructions by a bearing of the kind disclosed in U.S. Patent Specification No.

1 869,890. The use of segmentally spherical barrel rollers in a self-aligning roller bearing does no longer render it necessary to provide guide rims or shoulders but results in many sliding points, or lines, on either side of the ideal rolling path. (For an explanation of the significance of sliding points or lines reference is made to page 32 of A.

Palmgren's treatise "Grundlagen der Wälzlagertechnik" (The Principles of the Ball and Roller Bearing Art), 2nd edition, 1954, stating in summary - that the relative motion of two bodies of exactly cylindrical shape is a true rolling motion. If however the generatrix of one or both bodies is curved, only certain points, or lines, of the one body - roller - truly roll on the other - race track -- whereas all other points, or lines, slide.) Moreover, manufacture of the heavily curved barrel rollers is complicated and expensive because they can only be manufactured individually.

It is an aim of the invention, therefore, to improve a bearing of the kind referred to in the opening paragraph so as to achieve with the simplest feasible design and for any bearing size a radial and axial load capacity as high as possible yet low slide friction, and the components of which, particularly the rollers, can easily be manufactured.

Accordingly, the invention is directed to a single-row or double-row taper-rolling bearing comprising a rimless inner race, a rimless outer race, rollers and a cage, wherein at least the regions of the two end faces of each roller - in a longitudinal cross-sectional view thereof - are curved along their longitudinal extent, wherein the, or each, centre of the, or each, curvature is disposed on the opposite side of the bearing axis, wherein the smallest radius of the, or each, curvature is greater than ten times the length of the roller, and wherein the shape of the tracks of the inner and outer races is substantially the same as that of the rollers.

Preferably, the largest radius of the, or each, curvature is substantially thousand times the length of the roller. Thus, the reduction of the diameter of the rollers, at least in the regions of their end faces, and of the correspondingly shaped sections of the tracks, is only a slight one but necessarily causes a reduction of the distance between said sections of the tracks of the inner and outer races. As a result, the rollers are positionally secured in a direction transverse to their rolling direction. The components of the forces acting on the rollers in the direction of the roller axes, for example the centrifugal force of the rollers and the tilting forces of the races, are absorbed by the tracks. The disadvantageous guide rims are no longer required.Surprisingly, the rollers are not rolled or pushed into the races at their track sections where the distance between them narrows -- which in view of the aforementioned slight reduction of the diameter had generally been feared. The, or each, curvature is so slight - due to the aforementioned large radii - that the rolling characteristics of the rollers according to the invention can hardly be differentiated from those of the conventional cylindrical rollers. Thus, they have their advantages, for example their simple manufacture by mass-production methods, but not their disadvantages such as the necessity for providing guide rims or shoulders for them and of grinding the roller end faces.A greater number of slim rollers can without difficulty be inserted into the bearing whatever its size may be, thus achieving a high radial and axial load capacity of the taperrolling bearings. The sliding points, or lines, during the rolling motion are less than in the case of the conventional barrel rollers.

It is sufficient if the regions adjoining the two end faces of each roller are curved and if the intermediate regions between them is cylindrical.

However, the desired results - a bearing of high radial and axial load capacity and rollers capable of a more truly rolling motion in the tracks - can equally well be achieved with rollers convexly curved with the same radius along their entire length. Moreover, it is even easier to massproduce these rollers than rollers only the end regions of which are curved. No matter which of these two types of rollers are used, a bearing fitted with such rollers curved with radii falling within the limits already referred to can hardly be distinguished, as far as the true rolling motion is concerned, from a taper-rolling bearing fitted with cylindrical rollers.

In order to ensure easy assembly of a bearing according to the invention with the greatest possible number of rollers, including sliding of the outer race over the already positioned rollers, it is advantageous if the centre of the, or each, curvature is disposed either in a plane containing the outer race's end face which areally is the smaller of the two or in a plane extending parallel with said one plane outside the bearing on the side of said areally smaller end face.

A taper-rolling bearing according to the invention may be a single-row one. However, the same advantages prevail in the case of a double row bearing in X- or O-arrangement. In this instance, it is essential for the purpose of assembly that at least one of the races is divided if it is desired to insert the greatest possible number of rollers into the bearing.

The invention will hereinafter be explained in more detail with reference to some embodiments thereof illustrated in the accompanying drawings, in which: Fig. 1 is a cross-sectional view of part of a single-row taper-rolling bearing according to the invention including rollers having curved end regions and a cylindrical intermediate region; Fig. 2 is a cross-sectional view of a bearing similar to that of Fig. 1 but fitted with rollers convexly curved with the same radius along their entire length; Fig. 3 is a cross-sectional view of a double-row bearing similar in construction to that according to Fig. 2; Figs. 4a to 4c iliustrate, for the purpose of comparison, conventional rollers and rollers according to the invention as shown in Fig. 2.

The single-row taper-rolling bearing illustrated in Fig. 1 comprises an outer race 1, an inner race 2, a window-type cage 3 and rollers 4. The latter nave a cylindrical mid-region 4' but the two regions 4" adjoining the end faces 6 are curved along their longitudinal extent, the start of the curvatures and thus the reduction of the roller diameter being indicated by the arrows 5. Tracks 1' and 2' respectively of the outer race 1 and the inner race 2 are correspondingly shaped.The curvatures - exaggeratedly illustrated -- along both sections of the tracks corresponding to the roller regions 4" cause a narrowing of the distance between the outer race 1 and the inner race 2 so that the rollers 4 are prevented, inspite of the absence of guide rims, from moving in axial direction.

The embodiment illustrated in Fig. 2 is of similar construction but each of its rollers 9 is convexiy curved with the same radius along its entire length. The rollers are arranged between an outer race 7 and an inner race 8, both having tracks the shape of which is again substantially the same as that of the rollers 9. The centre 11 of the roller curvature is located far beyond the bearing axis 10 in a plane parallel with the plane containing the outer race's 7 end face which areally is the smaller one of its two end faces, that is io say the right-hand end face in the embodiment illustrated. The radius 12 of the curvature is greater than ten times the roller length 13.As a result of the - again exaggeratedly illustrated -- curvature having the radius 12 in conjunction with the correspondingly curved race tracks the rollers 9 are secured in axial direction.

As will be seen from Fig. 3, double-row bearings too may be made in accordance with the invention. In this embodiment, two bearings of the kind illustrated in Fig. 2 are combined in an 0arrangement. The important components are two inner races 14, two rows of rollers 15 corresponding in shape to the rollers 9 of Fig. 2 and a one-piece outer race 1 6. From the point of view of manufacture and operation such a construction is far superior to, for example, a tworow tapered-roller bearing.

Since, as already indicated, the curvatures of the rollers illustrated in Figs. 1 to 3 are exaggerated, Figs. 4a, 4b and 4c have been added.

Fig. 4a illustrates a conventional cylindrical roller, Fig. 4b a roller with a large radius of curvature according to the invention and Fig. 4c a conventional barrel roller. When comparing these rollers, it is evident that the roller of Fig. 4b is considerably more similar to the roller of Fig. 4a than to that of Fig. 4c. Thus, their insertion into a bearing having corresponding track profiles produces the advantages of the taper-rolling bearings with cylindrical rollers but without their disadvantages of guide rims. Since a roller according to the invention can be mass-produced, its manufacture is considerably cheaper than that of the barrel roller of Fig. 4c, not to mention the possibility of producing the former in lengths greater than the latter. In contrast, a barrel roller, due to its pronounced curvature, can only be manufactured individually.

Claims

1. A single-row or double-row taper-rolling bearing comprising a rimless inner race, a rimless outer race, rollers and a cage, wherein at least the regions of the two end faces of each roller - in a longitudinal cross-sectional view thereof - are curved along their longitudinal extent, wherein the, or each, centre of the, or each, curvature is disposed on the opposite side of the bearing axis, wherein the smallest radius of the, or each, curvature is greater than ten times the length of the roller, and wherein the shape of the tracks of the inner and outer races is substantially the same as that of the rollers.

2. A taper-rolling bearing according to claim 1, wherein the, or each, curvature is a circular sector.

3. A taper-rolling bearing according to claim 1 or claim 2, wherein the largest radius of the, or each, curvature is substantially thousand times the length of the roller.

4. A taper-rolling bearing according to any of the preceding claims, wherein the centre of the, or each, curvature is disposed either in a plane containing the outer race's end face which areally is the smaller of the two or in a plane extending parallel with said one plane outside the bearing on the side of said areally smaller end face.

5. A single-row or double-row taper-rolling bearing, construction, arranged and adapted to operate substantially as herein described with reference to the accompanying illustrative drawings.