Im ^p rovements in and relating to bearings and process for producing the same

This invention relates to bearings, in particular to bearings having an inner and an outer race housing rolling elements within a cage. The improvement relates to the mating arrangement of a bearing and a shaft or housing or both to prevent relative rotation with respect to each other without or only very minimally compromising the strength of the bearing.

Background

Bearings such as ball bearings and roller bearings are commonly used in machines, motors, gearboxes, vehicles and the like for supporting shafts that transfer rotational power (or thrust) or support loading.

A typical plain "ball" bearing of the prior art comprises a cylindrical outer race and a cylindrical inner race between which are housed a plurality of solid balls that are spaced evenly apart by a cage structure, the solid balls may rotate in ball tracks provided in the inner surfaces of the outer and inner race.

Roller bearings and needle bearings, either plain or tapered or special purpose, are constructed similarly to ball bearings, except rollers or needles, respectively, are used in place of the balls.

For the purposes of the description and claims, these types of bearings will be collectively defined and referred to as "bearing", "ball bearing" or "ball bearings".

The outer surface of the inner (smaller diameter) race of a ball bearing provides an aperture into which a shaft may be housed. The shaft is usually fitted to the ball bearing by an interference fit. The outer (larger diameter) surface of the outer race is mounted in a housing similarly utilising an interference fit. In some cases the bearings are secured by grub screws or circlips.

An interference fit of ball bearings to shafts is the current preferred arrangement for use with heavy loads. However, problems with interference fits often occur due to

wear or heat build up that causes the ball bearing to expand and the shaft to slip due to loss of factional contact with the ball bearing. This can result in damage/failure of the ball bearing and/or damage to the shaft.

It is well known that a preferred way to mate one component such as, for example, a pulley to a power transmitting shaft is by means of a keyed shaft/pulley arrangement. In this arrangement, a square sided longitudinal groove (or keyway) is formed in the surface of the shaft and a complementary keyway is formed in the complementary mating surface of the pulley. The respective keyways in the pulley and shaft are aligned and a square sided key inserted to therefore prevent relative rotation between the two components.

To date it has not been possible to use this arrangement to mate a shaft in the inner race of a ball bearing because the keyway in the inner race of the ball bearing would seriously compromise the strength and shape of the ball bearing. Further, the races of ball bearings are hardened and it would be very difficult to grind. In addition to seriously weakening the bearing, such a keyway might also cause the bearing to be distorted in the process.

Thus, it is an object of this invention to provide a keyed bearing for the purpose of mating with a keyed shaft or housing in which the integrity of the bearing is not or is only very minimally compromised.

Summary of the Invention.

According to a first aspect, the invention provides a bearing comprising:

a cylindrical outer race having an inner and outer surface;

a cylindrical inner race, concentric with said outer race, having an inner and outer surface;

a plurality of evenly spaced rolling elements housed between said inner surfaces;

wherein the edge faces of the cylindrical outer and inner races define the sides of the bearing;

characterized in that at least one indentation is provided in the edge face of each side of the inner race, wherein said indentation at one side is aligned with an indentation in the opposite side.

In a preferred embodiment the said indentation in the edge face of each side is bevelled toward the inner surface of the inner race. The bevel angle is in the range of 20-80 degrees, preferably 45 degrees.

Preferably, the bearing is in combination with a key for mating with said bearing. The key comprises an elongate body having a tooth at each end that is shaped to complement the shape of the indentations in the inner race. The elongate body of the key has a first surface located between said teeth that is transversely curved to conform to the curved surface of the inner race; second, third surfaces depending from said first surface, and a fourth surface extending perpendicularly between the adjoining second and third surfaces.

According to a second aspect, the invention provides a bearing comprising:

a cylindrical outer race having an inner and outer surface;

a cylindrical inner race, concentric with said outer race, having an inner and outer surface;

a plurality of evenly spaced rolling elements housed between said inner surfaces;

wherein the edge faces of the cylindrical outer and inner races define the sides of the bearing;

characterized in that at least one indentation is provided in the edge face of each side of the outer race, wherein said indentation at one side is aligned with an indentation in the opposite side.

According to a third aspect, the invention provides a method of adapting a bearing as hereinbefore defined comprising the step of grinding at least one indentation in the edge face of each side of the inner or outer or both races of an existing ball bearing, wherein an indentation in one side is aligned with an indentation in the opposite side.

According to a fourth aspect, the invention provides a key for use with a bearing as described in the first aspect comprising an elongate body having a tooth at each end that is shaped to complement the shape of the indentations in the inner race.

The key has a first surface located between said teeth that is transversely curved to conform to the curved surface of the inner race; second, third surfaces depending from said first surface, and a fourth surface extending perpendicularly between the adjoining second and third surfaces.

Detailed Description of Preferred Embodiments

In order that the invention may be more readily understood and so that further features thereof may be appreciated, the invention will now be described, by way of example and with reference to the accompanying drawings in which:

Figure IA: illustrates a ball bearing according to the invention.

Figure IB: is a cross section of a ball bearing as illustrated in figure IA.

Figure 1C: illustrates an end view of a key according to the invention.

Figure 2 A: illustrates an end view of a ball bearing according to another preferred embodiment of the invention.

Figure 2B: illustrates a" side view of a ball bearing as illustrated in figure 2 A.

Figure 2C: illustrates a side view of a key according to the invention.

Figure 2D: illustrates a cross-sectional view of a key as illustrated in figure 2C.

Figure IA depicts a sealed ball bearing 1 according to the invention.

The ball bearing 1 comprises a cylindrical outer race 2, and a cylindrical inner race 3. The cylindrical outer race 2 and cylindrical inner race 3 each have an inner 2i and 3i and an outer surface 2o and 3o. The side edge faces 2e and 3e of the cylindrical outer race 2 and inner race 3 define the sides of the ball bearing 1. Optional seals 4 conceal the ball races of the ball bearing 1 which comprise a plurality of solid balls B (or rollers in the case of a roller bearing) that are spaced evenly apart by a cage structure (not shown), wherein the solid balls may rotate in ball tracks 2t and 3t provided in inner surfaces 2i and 3i of the outer and inner race.

Indentations 5 are provided in the side edge faces 3e of the inner race 3. The indentations 5 are located at each side face 3e of the inner race 3, and do not extend through the inner race 3 in any direction, as illustrated in figure IB. Preferably, the indentations 5 are made as small as possible so as not to compromise the integrity of the ball bearing 1. As shown in figure IB, the indentations 5 may comprise the angular notching of the side edge faces 3e of the inner race 3. An indentation in one side edge face 3e of the inner race 3 is aligned with an indentation in the opposite side face 3e.

The angle of the indentations is in the range of 20-80 degrees, preferably 45 degrees. The indentations may be formed during production of new ball bearings. Alternatively, such indentations may be ground into the edge of existing ball bearings.

Figures IA and IB illustrate a ball bearing 1 having two pairs of aligned indentations 5 adapted to receive two keys 10, however, it will be appreciated that a ball bearing according to the invention may comprise only one pair of indentations 5, or even three or more pairs.

Figure 1C illustrates a key 10 for mating into a ball bearing according to the invention. The key is adapted to be received in the indentations 5 of the ball bearing 1 shown in figures IA and IB. The key comprises an elongate body having a tooth 13 at each end that is shaped to complement and fit into the respective indentations 5 provided in the inner race 3 of the ball bearing 1. The key 10 has a ball bearing engaging surface 12 between the teeth 13 that is curved complementary in shape to the contacting surface of the inner race 3o. The key also has a surface 11 adapted to be engaged in a complementary key-way in a shaft (not shown). The surface 11 may be any shape, in figure 1C the preferred shape of surface 11 is shown as three adjoining sides of the elongate body of the key.

In use, the key 10 is mated to the ball bearing 1 such that the teeth 13 of the key 10 engage in the indentations 5 of the bearing 1 (see figure IA). A shaft (not shown), having a key- way complementary to and aligned with the surface 11 of the key 10 may then be fitted into the aperture provided by the inner race 3 of the ball bearing 1 such that the shaft engages the key 10 which prevents relative rotation of the inner race 3 of the ball bearing 1 with respect to the shaft.

Figures 2A and 2B show a sealed ball bearing 20 according to another preferred embodiment of the invention.

Figure 2A shows a sealed spherical ball bearing 20 comprising a substantially cylindrical outer race 21 and a cylindrical inner race 22 which each have an inner and an outer surface. The side edges of the cylindrical outer race 21 and inner race 22 define the side of the ball bearing 20. The ball bearing shown is similar to that shown in figures IA and IB and comprises within the outer race 21 and inner race 22 a plurality of solid balls that are spaced evenly apart by a cage structure, wherein the solid balls may rotate in ball tracks provided in inner surfaces of the outer and inner race.

In the embodiment shown in figure 2A, the cylindrical inner race 22 is wider than the cylindrical outer race 21 and thus extends either side of the ball bearing to create a flange 23 a and 23b on each side of the ball bearing 20.

Each flange 23a and 23b has an indentation 24a and 24b. The indentations 24a and 24b shown in figure 2A span a substantial amount of the width of each of the flanges 23a and 23b, to provide as strong locking means as possible. It will be appreciated that the size of the indentations 24a and 24b may be larger or smaller depending on the intended application of the ball bearing 20. For example, indentations could be shaped as shown in figure IB.

Also of note in figure 2 A is that the flanges 23 a and 23b are of different widths. It will be appreciated that the flanges 23a and 23b may be any size and may also be the same size as each other. Further, it will be appreciated that the flanges do not necessarily need to be formed by the inner race of the ball bearing. The flanges may be formed from other material integral with the ball bearing, or from material attached to the ball bearing.

A ball bearing having indentations in flanges, such as those shown in figure 2A, has the advantage of allowing for larger indentations than bearings without flanges, which would allow for stronger engagement with a complementary key.

Figure 2B is a side view of the ball bearing 20 shown in figure 2A. The figure shows the outer race 21 and inner race 22 of the bearing 20. The bearing has seals 25 that conceal the contents of the ball bearing which comprise a plurality of solid balls that are spaced evenly apart by a cage structure, wherein the solid balls may rotate in ball tracks provided in the outer and inner race. The indentation 24 is located in the flanges that can be seen in figure 2A, but which cannot be seen clearly in figure 2B due to the perspective. It will be understood that the indentations are located in the flanges and not in the contacting surface of the inner race 22.

Figure 2C is a side view of a key 30 for mating into a ball bearing according to the invention. The key 30 is adapted to be received in the indentations 24 A and 24B of the ball bearing shown in figures 2A and 2B. The key 30 comprises an elongate body having teeth 32a and 32b at each end that are shaped to complement and fit into the indentations 24a and 24b provided in the inner race 22 (flange) of the ball bearing 20. The key 30 has a ball bearing engaging surface 31 between the teeth 32a and 32b that is curved complementary in shape to the contacting surface of the inner race 22. The

key 30 also has a surface 33 adapted to be engaged by a complementary key-way in a shaft. The surface 33 of the key 30 may be any shape, in figure 1C the preferred shape of surface 33 is shown as three adjoining sides of the elongate body of the key.

Figure 2D is a cross-sectional view of a key 30 as shown in figure 2C, the cross section is taken through a line such as that indicated by the dashed line labelled X in figure 2C.

In use, the key 30 is mated to the ball bearing 20 such that the teeth 32a and 32b of the key engage in the indentations 24a and 24b of the ball bearing 20. A shaft, having a key-way complementary to the surface 33 of the key 30 may then be fitted into the aperture, provided by the inner race of the ball bearing 20, such that the shaft engages the key 30 which prevents relative rotation of the inner race 22 of the ball bearing 20 with respect to the shaft.

As with the embodiment illustrated in figures IA, IB and 1C, it will be appreciated that the embodiment of the invention illustrated in figures 2A, 2B, 2C and 2D is a preferred embodiment only. The indentations and keys may be shaped differently to give the same benefit of not compromising the strength of the inner race of the ball bearing.

For example, a ball bearing having a flange on one side only may have one or more indentations in the flange as shown in figures 2A and 2B, and on the side of the ball bearing having no flange, one or more indentations such as those shown in figures IA and IB may be present. In such a situation, a key having a tooth at one end shaped as shown in figure 2C and 2D and a tooth at the other end shaped as shown in figure 1C would preferably be used to lock a shaft into the ball bearing.

Further, the invention may be applied to a multi-keyed/splined arrangement.

In an alternative embodiment, it is envisaged that the outer race of a ball bearing may be keyed in a similar manner to that described above with regard to the inner race. The housing that the bearing is to be mounted in would be provided with a complementary keyway.

Another aspect of the invention provides in combination, a ball bearing according to the invention and a key according to the invention.

A further aspect of the invention provides a method of adapting an existing ball bearing to a ball bearing according to the invention. In particular, there is provided a method of adapting an existing ball bearing comprising the step of grinding at least one indentation in the external side face of each side of the inner race of an existing ball bearing, wherein an indentation in one side is aligned with an indentation in the opposite side, and wherein the indentations are engageable with complementary shaped teeth on a key.