GB1591194A

GB1591194A - Idler roller assemblies

Info

Publication number: GB1591194A
Application number: GB4019379A
Authority: GB
Original assignee: Fyson & Son Ltd C J R
Current assignee: Fyson & Son Ltd C J R
Priority date: 1978-03-29
Filing date: 1978-03-29
Publication date: 1981-06-17

Description

(54) iMPROVEMENTS m IDLER ROLLER ASSEMLBES (71) We, C. J. R. FYSON & SON LIMITED, a British Company, of 67 Paddock Street, Soham, Ely, Cambridge, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: Field of invention This invention concerns idler roller assemblies for conveyors and the like.

Background 1. Conveyors and the like often have to be located in unsuitable environments often containing a high content of airborne dust and dirt and the bearings for rotating parts, particularly those which are not driven, are very vulnerable to the ingress of such airborne dust and dirt as well as the ingress of particulate material etc. from the conveyor itself depending on the load which is carried.

2. Conveyors also often have to be situated in hazardous areas where the risk of fire or explosion is great and in the event that a bearing was to fail in such an environment, the heat produced by such a bearing when being run in a failed condition and/or sparks produced by the rubbing of metal on metal could easily cause a serious fire or explosion to occur in such an environment.

3. Access to the side of a conveyor very often at waist height means that the ends of the idler rollers are located at just the righ height for clothing and hands etc. to be trapped accidentally between the rotating outer and stationary inner members forming the idler roller.

It is with all these points in mind that an alternative design of idler roller assembly is proposed herein.

Although the invention is particularly applicable to idler rollers for conveyors it is of equal application to any rollers which are to be mounted so as to be free to rotate.

Objects of the invention It is an object of the invention to provide an improved idler roller assembly for conveyors and the like to eliminate the risks associated with the three hazards mentioned above.

The invention According to the present invention an idler roller assembly for a conveyor or the like comprises a cylindrical sleeve into which is pressed a plug member, moulded from plastics materal the outer diameter of which is an interference fit with the internal diameter of the cylindrical sleeve and having a central circular aperture into which is firmly fitted the outer member of a cylindrical multiple part bearing assembly, an annular shoulder within the central circular aperture against which at least part of the outer bearing member locates to prevent the latter from being pushed axially completely through the said aperture, an end closure member also formed from plastics material which serves to enclose the bearing assembly within the central aperture in the plug member and is an interference fit on a stationary shaft which extends through and is itself an interference fit or keyed to the inner race member of the multiple part bearing and a locking means for keeping the end closure member correctly positioned on the said shaft.

In this design, the locking means is preferably a Sprag locking ring of spring steel the outer peripheral region of which is embedded in the annular cap so that the inwardly directed flanges of the locking ring are free from plastics material and can engage the smooth cylindrical surface of the shaft, the annular moulding extending radially to cover the inwardly directed flanges of the locking ring and defining a circular aperture which is a tight fit on the circular shaft.

In the preferred design, the end closure member is of approximately the same diameter as that of the cylindrical sleeve forming the roller so that only a peripheral ring of small thickness remains between the member and the plug member, and is exposed to constitute a non-metallic protective annular peripheral edge to the roller at each end of the cylindrical sleeve.

The preferred form of construction thus causes the multiple part bearing to be effectively totally enclosed, since the labyrinth seal prevents the ingress of dirt and moisture to the internally located bearing.

In the event that the bearing should fail, the plug member and end closure member constitute two parts of a short life bearing and the roller will remain correctly axially and radially located by means of the interacting grooves and lips of the annular labyrinth seal. By forming the latter from a material which is known to be a good sliding bearing material ,the two parts can rotate relative one to the other without any risk of undue overheaing. Any metal to metal contact in the failed bearing is totally enclosed within the labyrinth seal so that sparks from he metal to metal contact will no cause a fire or explosion and the mounting can be operated in that condition for a considerable period of time, and in general long enough to allow an organised rundown of the conveyor to allow a replacement mounting to be fitted.

'The interfitting labyrinth seal and the use of appropriate plastics materials, such as DELRIN (Trade Mark) or another Acetal resin, for the plug member and end closure member serve to provide a mounting which is both relia'ble and safe even in hazardous fire risk conditions and which if constructed in accordance with the preferred feature of the invention will also reduce the risk of clothing etc. being caught and dragged into the rotating end of the rotatable member.

Preferably the end closure member additionally includes a section which axially abuts the internal race member of the multiple part bearing, the axial abutment serving to axially locate the end closure member relative to the plug member and by virtue of the locking means which prevents axial movement of the end closure member away from the bearing, additionally serves to locate the multiple part bearing relative to a cylindrical sleeve member forming the rotatable member.

The invention will now be described by way of example with reference to the accompanying drawings.

Description of the Figures Fig. 1 is a side view of an idler roller for a conveyor, a left-hand part of which is shown in cross-section to reveal the detail of the mounting assembly which constitutes an embodiment of the invention, Fig. 2 is an end view of the idler roller of Fig. 1, Fig. 3 is a cross-section through the lefthand end of a similar idler roller to that shown in Fig. 1 in which the locking means comprises a CIRCLI;P, Fig. 4 is an end view of the idler roller shown in Fig. 3 and Figs. 5, 6, 7 and 8 illustrate alternative shaft ends to the type shown in Figs. 1 and 3.

Detailed description of the embodiments Referring first of all to the embodiment shown in Figs. 1 and 2, an idler roller comprises an outer cylindrical sleeve 10 which is mounted to be freely rotatable -about a stationary shaft 12 having opposite ends formed with pairs of fiats which are best seen in Fig. 2 and designated by reference numerals 14 and 16. The fiats are formed according to ISO R1537 to fit standard slots in supporting brackets.

At each end of the sleeve 10 a mounting is provided detail of which is shown at the left-hand end by way of a cross-section view.

The mounting comprises a plug generally designated 18 having an outer cylindrical surface which is adapted to be an interference fit within the sleeve 10 and includes an annular shoulder 20 around its external periphery the outer diameter of which is commensurate with the external diameter of the sleeve 10 so that when the plug 18 is pushed into an end of the sleeve 10 the surface of the annular shoulder 20 is flush with the outer surface of the sleeve 10.

In accordance with the invention claimed in our Specification No. 1 591193 (Application No. 16039/77 from which the present application is divided), the annular shoulder 20 extends radially inwardly by only a small distance and the remainder of the outer end face of the plug member is formed with two annular grooves 22 and 24 to receive annular lips 26 and 28 respectively of an end closure member 30 and to form therewith a labyrinth seal.

As shown the end closure member 30 additionally includes a third inner annular lip 32 which cooperates with the internal cylindrical surface of the plug member 18 to form a further part labyrinth and also includes an inner integral portion in the form of a boss 34 which is a tight fit on the shaft 12.

The cylindrical interior of the plug member 18 also includes an internal annular shoulder 38 between the section of one internal diameter and a section of reduced internal diameter 39. Within the first mentioned section is located as an interference fit the outer race member of a roller or ball bearing assembly 36, the right hand end of the said outer race member as shown in Fig. 1 abutting against the annular shoulder 38.

The bearing assembly includes an inner race member 40 which is an interference fit or is keyed to the shaft 12 and the lefthand end of the inner - race member (as shown in Fig. 1) abuts against the inner end of the boss 34 of the end closure member 30.

The end closure member 30 is axially retained in position by means of a locking cap 42 which comprises an annular plastics ring into which at least in part is embedded a Sprag locking ring 44 of spring steel with the internal flanges thereof extending freely from the plastics ring to engage on and bite into the surface of the shaft 12.

With the locking cap 42 of the type shown in Fig. 1, it will be seen that this can be pushed on the shaft in a left to right direction but cannot be pulled off the shaft without the aid of a special tool.

The plug member 18, the end closure member 30 and annular cap 42 are preferably formed from a stable copolymer Acetal resin material such as the type manufactured under the Trade Mark DELRIN.

With reference to Fig. 2 it will be seen that the area of the end of the roller which actually rotates relative to the stationary shaft 12 has been reduced to a peripheral ring comprising the annular shoulder 20 and the greater part of the end surface of the roller is completely stationary since it is fitted onto the stationary shaft 12.

Referring to Figs. 3 and 4, an alternative locking means comprises a CIRCLIP typically constructed to DIN 6799 which is fitted into an annular groove (not shown) formed in the external surface of the shaft 12 and in an appropriate position along the length thereof, the shaft 12 being formed wtih two such grooves axially spaced apart by the overall length of the roller so that the two grooves are just exposed beyond the ends of the two end closure members 30 the one at the left-hand end and the other at the right-hand end of the idler roller as shown in Fig. 1. This alternative locking means is cheaper than the arrangement shown in Figs. 1 and 2 and does not need a special tool to remove it.

Where the shaft 12 is to be fitted by means of a locking nut, the protruding end of the shaft 12 may be longer than that shown in Figs. 1 and 3 and may be formed with a screw thread profile as shown at 46 in Fig. 5 so that lock nuts 48 and 50 can be screwed thereon.

Where the end of the shaft is to be located by means of a split pin or the like the end of the shaft may be formed with a diametrical hole 52 such as shown in Fig.

6.

Where the shaft is to be fited into an aperture having one flat only, the ends of the shaft 12 may. be formed with a single fiat 54 such as shown in Fig. 7 which may extend completely to the end of the shaft or as shown in Fig. 8 need not extend completely- to the end of the shaft so as to provide a two-directional location in the aperture (i.e. both rotational and axial location).

WHAT WE CLAIM IS:- 1. An idler roller assembly for a conveyor or the like comprising a cylindrical sleeve into which is pressed a plug member, moulded from plastics material the outer diameter of which is an interference fit with the internal diameter of the cylindrical sleeve and having a central circular aperture into which is firmly fitted the outer member of a cylindrical multiple part bearing assembly, an annular shoulder within the central circular aperture against which at least part of the outer bearing member locates to prevent the latter from being pushed axially completely through the said aperture, an end closure member also formed from plastics material which serves to enclose the bearing assembly within the central aperture in the plug member and is an interference fit on a stationary shaft which extends through and is itself an interference fit or keyed to the inner race member of the multiple part bearing and a locking means for keeping the end closure member correctly positioned on the said shaft.

2. An idler roller assembly as claimed in claim 1 in which the end closure member is of approximately the same diameter as that of the cylindrical sleeve forming the roller so that only a peripheral ring of small thickness remains between the member and the plug member, and is exposed to constitute a non-metallic protective annular peripheral edge to the roller at each end of the cylindrical sleeve.

3. An idler roller assembly as claimed in claim 1 or 2 in which the end closure member additionally includes a section which axially abuts the internal race member of the multiple part bearing, the axial abutment serving to axially locate the end closure member relative to the plug member and by virtue of the locking means which prevents axial movement of the end closure member away from the bearing, additionally serves to locate the multiple part bearing relative to the cylindrical sleeve member forming the roller.

4. An idler roller assembly as claimed in any of claims 1 to 3 wherein said plastics material is an Acetal resin.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. shoulder 38. The bearing assembly includes an inner race member 40 which is an interference fit or is keyed to the shaft 12 and the lefthand end of the inner - race member (as shown in Fig. 1) abuts against the inner end of the boss 34 of the end closure member 30. The end closure member 30 is axially retained in position by means of a locking cap 42 which comprises an annular plastics ring into which at least in part is embedded a Sprag locking ring 44 of spring steel with the internal flanges thereof extending freely from the plastics ring to engage on and bite into the surface of the shaft 12. With the locking cap 42 of the type shown in Fig. 1, it will be seen that this can be pushed on the shaft in a left to right direction but cannot be pulled off the shaft without the aid of a special tool. The plug member 18, the end closure member 30 and annular cap 42 are preferably formed from a stable copolymer Acetal resin material such as the type manufactured under the Trade Mark DELRIN. With reference to Fig. 2 it will be seen that the area of the end of the roller which actually rotates relative to the stationary shaft 12 has been reduced to a peripheral ring comprising the annular shoulder 20 and the greater part of the end surface of the roller is completely stationary since it is fitted onto the stationary shaft 12. Referring to Figs. 3 and 4, an alternative locking means comprises a CIRCLIP typically constructed to DIN 6799 which is fitted into an annular groove (not shown) formed in the external surface of the shaft 12 and in an appropriate position along the length thereof, the shaft 12 being formed wtih two such grooves axially spaced apart by the overall length of the roller so that the two grooves are just exposed beyond the ends of the two end closure members 30 the one at the left-hand end and the other at the right-hand end of the idler roller as shown in Fig. 1. This alternative locking means is cheaper than the arrangement shown in Figs. 1 and 2 and does not need a special tool to remove it. Where the shaft 12 is to be fitted by means of a locking nut, the protruding end of the shaft 12 may be longer than that shown in Figs. 1 and 3 and may be formed with a screw thread profile as shown at 46 in Fig. 5 so that lock nuts 48 and 50 can be screwed thereon. Where the end of the shaft is to be located by means of a split pin or the like the end of the shaft may be formed with a diametrical hole 52 such as shown in Fig. 6. Where the shaft is to be fited into an aperture having one flat only, the ends of the shaft 12 may. be formed with a single fiat 54 such as shown in Fig. 7 which may extend completely to the end of the shaft or as shown in Fig. 8 need not extend completely- to the end of the shaft so as to provide a two-directional location in the aperture (i.e. both rotational and axial location). WHAT WE CLAIM IS:-

1. An idler roller assembly for a conveyor or the like comprising a cylindrical sleeve into which is pressed a plug member, moulded from plastics material the outer diameter of which is an interference fit with the internal diameter of the cylindrical sleeve and having a central circular aperture into which is firmly fitted the outer member of a cylindrical multiple part bearing assembly, an annular shoulder within the central circular aperture against which at least part of the outer bearing member locates to prevent the latter from being pushed axially completely through the said aperture, an end closure member also formed from plastics material which serves to enclose the bearing assembly within the central aperture in the plug member and is an interference fit on a stationary shaft which extends through and is itself an interference fit or keyed to the inner race member of the multiple part bearing and a locking means for keeping the end closure member correctly positioned on the said shaft.

5. An idler roller assembly as claimed

in claim 1 and constructed, arranged and adapted to operate substantially as herein described by way of example with reference to and as illustrated in accompanying drawings.