This invention relates to bearings for rollers and the like, and provides an improved bearing structure for overcoming a disadvantage which applies in the use of roller bearings in certain industrial applications, in particular where roller bearings are used to provide conveyors in food factories and manufacturing plants.

In food factories, for the handling and/or manufacture of food stuff, it is common to use what is sometimes referred to as roller decking. Roller decking comprises a plurality of rotatively supported rollers which lie parallel and in spaced relationship and define a surface for the supporting of articles and foodstuff so that the articles can be conveyed across the decking by rotation of the rollers for example so as to move away from or to processing machinery or to move from location to location in the plant. The rollers may be arranged in an inclined plane so that the food articles will travel thereover by virtue of gravity or in some cases the rollers may be driven for the propulsion of articles. Although the majority of applications comprise the aforesaid rollers which comprise a sleeve and a pair of roller bearings in the respective ends, in fact the sleeve can in some instances be dispensed with and the roller decking being defined simply by pairs of roller bearings which are spaced apart but in axial alignment. Such pairs of rollers can support for example articles of a defined shape such as loaves of bread or boxes.

In any event, in food factories it is often the official requirement that the conveying equipment must be regularly washed down using washing hozes. Because this washing down takes place, the maintenance of hygienic conditions is important, and it is important to ensure that bacteria traps

are not allowed to form in the machinery, at least as far as possible.

Heretofore, the sleeves of roller bearings have tended to form bacteria traps especially where the water which is jetted onto the apparatus can leak into the interior of the sleeve.

To overcome this difficulty certain bearing constructions have been adopted for example as set forth in our International Patent Application PCT/GB92/00070.

Roller bearings as described in said International Patent Application are designed to be mounted between a pair of spaced support rails such as angle irons or u-sectioned brackets, the mounting being by means of stub shafts forming part of or engaging the respective bearings in the ends of the rollers.

The present invention is concerned with roller bearings of the type set forth in said International patent application insofar as the roller bearings are designed to be as bacteria free and hygienic as possible having regard to the fact that they are periodically washed down, but wherein a number of improved mounting arrangements for the stub shaft are set forth.

As explained in said International patent application, as far as possible the components of the bearing are of plastics material so as not to corrode under the action of the washing fluid, but it is normally the practise to use stainless steel rolling elements such as the balls of the bearing in order to provide the necessary long life.

Equally, it is usual to provide that the stub shafts which

support the bearings are of metal and again these will be selected so as to be non-corrodable and so as to have a long life.

The present invention essentially is concerned with ensuring that the stub shafts can be supported in a rigid manner or as rigid manner as possible on the support rails. This prevents any malfunctioning of the roller such as the tracking out of the sleeve from the roller bearings whic can happen if the stub shafts which define the rotation axis are not sufficiently rigidly mounted and dip towards the centre of the roller decking.

A number of embodiments of roller bearing mountings are set forth in the accompanying drawings, wherein:-

Fig. 1 is a diagrammatic perspective view of a section of roller decking;

Fig. 2 is a sectional elevation to an enlarged scale taken on the line II-II in Fig. 1;

Figs 3, 4 and 5 are views similar to Fig. 2 but showing alternative embodiments;

Fig. 6 is a view similar to Fig. 1 but showing an alternative form of mounting rail for the roller decking; and

Fig. 7 is a sectional elevation similar to Fig. 2 but showing the roller bearings used in connection with the arrangement of Fig. 6.

Referring to the drawings, a section of roller decking is indicated by the reference numeral 10, and the decking will be seen to comprise side rails 12 and 14 of channel section

angle iron forming part of the decking frame, and between which extend a plurality of parallel, spaced and freely rotatable rollers 16. The decking illustrated is of the gravity type insofar as the plane which contains the rollers (which are identical) is inclined, so that the articles 18 to be transported by the roller decking in fact move down the decking under gravity, turning rollers 16 about their axes as the articles proceed.

Fig. 2 shows a cross-sectional view of one of the roller bearings used in the arrangement of Fig. 1, it being understood that there is a roller bearing at each end of each roller 16. Roller 16 as shown comprises a sleeve 20 which may be of steel or plastics or cardboard or other material or combination, and the roller bearing 22 is simply a push-fit into the end of the sleeve 20.

The roller bearing 22 comprises an outer bearing race 24, and an inner bearing race 26. The outer bearing race is in the form of a cup 28 which blanks off the interior of the sleeve 20 from the surrounding atmosphere. This prevents the ingress of any moisture or other material into the interior of the sleeve 20, whereby formation of bacteria trapped inside the sleeve is prevented. The outer race 24 is provided with a cylindrical outer portion 30 having at one end a flange 32 which abuts the end of the sleeve into which the bearing 22 is inserted as shown in Fig. 2. The outer bearing race 24 is also formed with a bearing track 34 on which the rolling element of the roller bearing runs, said element 36 being held in equi-angularly arranged relationship by means of a cage 38 of the roller bearing, and which is of conventional construction. The outer and inner races 24, 26 and the cage 38 preferably are of plastics material, whilst the roller bearing elements 36 are steel balls.

The balls 36 run on race tracks 34 in the outer race 24 and

51 on the inner race 26.

The inner bearing race 26 is also in the form of a closed cup 42, the central recesses then forming a bore 44 in which is received a support spindle 46 of stainless steel and which is secured to the adjcent side rail 14 by means of a nut 48. Inside the bore 44 of the inner race 26 is a compression spring 50 which reacts against the base of the bore 44 and the end of the spindle 46 thereby effecting a resilient support for the roller 16 when in use, it being borne in mind that there is a similar mounting arrangement at the opposite end of the roller.

The inner race 26 is further provided with a flange portion 50A which extends outwardly and into a shoulder 53 in the end face of the outer race 24 so as to leave a small annular gap

52 which although it serves to inhibit the amount of water or other liquid which can enter the bearing, is such as nevertheless to leave sufficient clearance to enable the inner and outer races 24 and 26 relatively to rotate in use without contact, and indeed to be relatively loosely fitted one in relation to the other to allow a considerable degree of play.

A forwardly projecting portion 54 of the inner race is provided externally with flats on opposite sides thereof so that it may be engaged by means of an appropriately dimensioned spanner and can be held from rotation whilst the nut 48 on the spindle is being tightened in order to tighten the nut to secure the spindle to the side rail 14 so that it will rigidly define the rotation axis of the roller.

The spindle 46 in fact comprises a sleeve 46A of hexagonal cross-section on its outer surface and provided with a

threaded bore which receives a threaded shank which also passes through the nut 48.

The sleeve 46A is received in a bore 44 which is of hexagonal cross section where engaged by sleeve 46A to ensure that there will be no relative rotation between the inner race and the sleeve 46A in use. The sleeve may be engaged in the inner race 26 so that it cannot be retracted therefrom although it is relatively slidable thereto.

To connect a roller with a pair of bearings as described and illustrated in Fig. 2, would require the nut 48 and the threaded spindle to be removed so that the roller can be positioned between the rails 12 and 14 and then to fit the roller to the rails, it is simply a matter of threading the spindle into the sleeve 46 followed by tightening of the nut 48. The sleeve 46A may be held from rotation by holding the flats on the projection 54 whilst tightening of the nut 48 takes place.

In use of the arrangement shown in Fig. 2, should it be that water when jetted on the apparatus to clean same, enters the gap 52, it passes freely over the balls 34 and into the interior of the cup 28, but it will also drain freely from the bearing because the bore of the cup 28 is shaped so as to provide no obstruction or water collection point, and eventually the water will run from the bearing through the gap 52 at the lower side of the bearing in Fig. 2. This is true of all of the bearing arrangements of the embodiments of the invention described herein.

In the other embodiments of the invention, the only significant difference concerns the manner of fixing the spindle to the mounting bar 14, and therefore the same reference numerals as used in relation to Figs. 1 and 2 are

used where possible to indicate the same parts.

In the arrangement of Fig. 3, the spindle 46 is defined by a threaded shaft and the bore of the inner race 26 is similarly threaded so that it is simply a matter of turning the nut 48 in order to tighten the inner race 26 directly to the frame 14. Again extension 34 may be provided with spanner engaging flats to prevent the inner race from turning as tightening of the nut 48 takes place. Nut 48 may in fact be a bolt head integral with the threaded shaft 46.

Connection of the rollers with the bearings according to Fig. 3 to the frame members 12 and 14 will be readily understood. The threaded shafts 46 are initially withdrawn, and the roller is positioned between the frame members 12 and 14 until the bores 44 align with apertures in the frames 12 and 14, and then the bolts 48/46 are simply threaded into the threaded bore 44, the inner races being held against rotation as necessary and tightening takes place until the inner races 26 are tightened against the frames 12 and 14 thereby defining rigidly mounted sub-shafts which define the axis of rotation of the roller.

In Fig. 4, the stub shaft 46 is of hexagonal cross section, and is simply welded to the adjoining frame 14 by welds 49. The bore of the inner race 44 is a corresponding haxagonal cross section so that the inner race cannot turn on the shaft 46.

The roller in this case is connected to the frame member by positioning the rollers between the frame members, followed by insertion of the spindles 46, followed by the application of the welds 49. It is noticed that this embodiment also includes the springs 50, whereas the said springs are understandably omitted from the embodiment of Fig. 3.

In the arrangement of Fig. 5, the stub shafts 46 are defined by spindles 47 which are anchored to the frame members 14 by means of nuts 48 and 55, these nuts being located at opposite sides of the frame member 14 as shown in Fig. 5.

To connect the roller bearings, the spindle 47 and nuts 48 and 55 are detached from the frame 14 and the roller is placed in position between the frames 12 and 14. Spindle 47 is threaded through nut 55 held to the opposite side of the frame 14 by a spanner or the like until the spindle engages rotationally in the bore 44 of the inner race 26, following which the respective nuts 55 and 48 are tightened together to trap the frame member 14 therebetween as shown in Fig. 5, thereby defining rigid stub axles on which the inner races 26 are slidable. The rollers are maintained centralised by means of the springs 50.

In the arrangement of Figs. 6 and 7, the frame members 12 and 14 are modified so as to be of angle iron section, and the top edges are provided with U-shaped slots to receive the spindles 46. The spindles are simply push-fitted into these slots and in order to enhance the rigidity of the positioning of the spindles 46, each spindle 46 is provided with a hexagonal shaft portion which engages in the bore 44 (of corresponding shape) of the inner race 26 and two larger diameter flanges 57, 59 which are spaced apart by the thickness of the plate of the frame, and are connected by a short axle portion 61 of a size to match the width of the slot in a frame member 14.

It will be understood that the spindles can simply be push- fitted into the slots in the frame edge and the enlarged flange portions 57 and 59 will trap the frame plate therebetween and hold the spindle shaft 46 rigid and in

a suitable position for retaining the roller. To fit rollers in this arrangement, the spindles 46 are first inserted in the inner races 26, and then the rollers are simply pushed into position. This particular design is effective for removal for cleaning and repair of the rollers.