GB2103303A

GB2103303A - Method of cleaning bearings

Info

Publication number: GB2103303A
Application number: GB08217865A
Authority: GB
Inventors: Francis M Finnighan
Original assignee: Alfa-Laval Cheddar Systems Ltd; Alfa Laval Cheddar Systems Ltd
Current assignee: Alfa-Laval Cheddar Systems Ltd; Alfa Laval Cheese Systems Ltd
Priority date: 1981-07-01
Filing date: 1982-06-21
Publication date: 1983-02-16

Abstract

A method of cleaning bearing surfaces between a spindle 24 and roller 25 in apparatus used in the handling or processing of food products, particularly slat conveyors. The spindle 24 has an axial bore 50 which opens into the clearance gap between the bearing surfaces, and cleaning fluid under pressure is supplied to the bore by a nozzle applied to the bore at one end of the spindle, the cleaning fluid flowing through the bore and over the bearing surfaces. A bush 38 of low- friction plastics material removes the need for lubricating oil. <IMAGE>

Description

SPECIFICATION Improvements in methods of cleaning apparatus used in the handling or processing of food products This invention relates to the cleaning of apparatus used in the handling or processing of food products, and is concerned more particularly but not exclusively to the cleaning of apparatus used in the manufacture of cheese.

Apparatus used in the manufacture of cheese must be cleaned immediately after use to. remove any traces of whey or particles of curd which may have become lodged in the apparatus, to avoid proliferation (growth) of micro-organisms present in starter culture which would cause microbial contamination of cheese subsequently manufactured in the apparatus, and it is the practice to fit such apparatus with c.i.p. (clean-in-place) equipment operable to spray and drench with cleaning liquid all parts of the apparatus which have been in contact with curd or whey. The whey however tends to seep between the bearing surfaces of relatively rotatable components in mechanisms such as chains or conveyors in the cheese making apparatus.Such bearing surfaces are not normally lubricated with oil since escape. of oil would contaminate the cheese, and the bearing surfaces are usually formed of low friction material such as Teflon (Registered Trade Mark). The c.i.p.

equipment at present in use does not clean surfaces such as bearing surfaces, which are not exposed to the spray of liquid, and it is necessary to dismantle mechanisms having bearings at frequent intervals in order to clean each individual component separately. This is a time-consuming operation, and of course the plant remains idle during dismantling, cleaning and re-assembling of the mechanisms.

According to the present invention there is provided a method of cleaning bearing surfaces in apparatus comprising a spindle having a bearing surface thereon and a component rotatably mounted on said spindle, said component having a bearing surface in sliding contact with said bearing surface on the spindle without lubricating medium therebetween, wherein the spindle is provided with a bore which opens to the interface between said bearing surfaces, and cleaning liquid is forced under pressure into said bore so that the cleaning liquid flows through said bore to said interface and flows over the bearing surfaces.

Conveniently, the bore in the spindle is open at one end thereof, and the cleaning liquid is supplied to the bore through a nozzle applied to the open end of the bore.

The cleaning method of the present invention is particularly applicable to the cleaning of link chains in which the links are pivotally connected to one another by transverse spindles, and to endless conveyors incorporating such link chains. Such chains may be fitted with rollers rotatably mounted on at least some of the transverse spindles and adapted to roll along tracks to support the chains and the conveyor. Each transverse spindle fitted with a roller can conveniently be provided with an axial bore which communicates with the interface between the bearing surfaces on the spindle and the roller, to enable the bearing surfaces to be cleaned with liquid in accordance with the invention. The bearing surfaces between the spindles and the links can conveniently be cleaned by the liquid discharging from the annular spaces between the spindles and the rollers.

A method of cleaning the bearing surfaces of chains in accordance with the invention and two different constructions of chains adapted to be cleaned by the method of the invention, the chains being incorporated in an endless slat conveyor, will now be described by way of example with reference to the accompanying drawings, in which:: Figure 1 is a plan view of the slat conveyor, Figure 2 is a view of the underside of the chains and one slat of the conveyor, the centre portion of the slat being cut away, Figure 3 is a side view of an enlarged scale of part of one of the side chains, Figure 4 is a cross sectional view taken along the line IV-IV in Fig. 3, and including a nozzle for supplying cleaning liquid, Figure 5 is a perspective view with the slats cut away, the two side chains being shown closer together for convenience, and part of the side chains being shown in exploded view, Figure 6 is a plan view of a metal plate for making an integral link and bracket for use in a modified construction of side chain, Figure 7 is an end view of the metal plate of Fig. 6, on a larger scale, after the plate has been shaped into the integral link and bracket, and Figure 8 is a cross-sectional view of part of the modified constructon of side chain.

Referring to Fig. 1, the conveyor comprises two endless side chains 10, 11 each mounted on two sprockets 12, 1 3 secured on transverse shafts rotatably mounted in a frame (not shown), and a plurality of transverse slats 14 mounted on and extending between the chains. The upper and lower runs of the chains are supported on guide rails (not shown) secured on the frame of the conveyor, and an electric motor 1 5 is arranged to drive the sprockets 1 2 and thereby pull the chains along the rails. The slats 14 may be of any suitable construction, but can conveniently be in the form shown in United States Patent Specification 4326626 and, as shown in Fig.

2, comprise a thin elongated metal plate 1 6 having the longitudinal margins 1 7 bent through an angle in excess of 90"C, and longitudinal strengthening means in the form of a V-shaped bar 1 8 having the ends thereof secured to plates 1 9 welded to the bent-over margins 1 7 of the plate 16, the centre portion of the plate being supported by a strut (not shown) on the centre of the bar 1 8. Conveyors having slats of this construction can provide a substantially flat upper surface but nevertheless be several metres wide and support a heavy load per unit area without the aid of additional supports between the chains.

Each of the side chains 10, 11 comprises pairs of outer links 20, 21 pivotally connected to pairs of inner links 22, 23 by transverse spindles 24, and rollers 25 rotatably mounted one on each spindle 24 between the inner links 22, 23. All the links are of the same length with the links of each pair parallel to one another. The links 20 are on the inboard side of the chain, that is the side adjacent the slats, and each link 20 is fitted with two of the spindles 24 located in apertures 30 (Fig.

4) arranged one adjacent each end of the link 20. Each spindle has a reduced diameter end 31 located in the aperture 30 and welded thereto, the spindles being arranged so that they project perpendicularly outwards from the link 20. The links 22 are each fitted with two cylindrical bushes 32 located in apertures arranged one adjacent each end of the link, the links 23 are similarly each fitted with two cylindrical bushes 33 arranged one adjacent each end of the link, and the links 21 are each fitted with two cylindrical bushes 34 located in apertures arranged one adjacent each end of the link. Each roller 25 comprises an annular body 35 having bevelled side walls 36, 37 and a cylindrical bush 38 secured in the central opening in the roller body.The ends of the bush 38 project outwards beyond the side walls 36, 37 and are each formed with an annular recess 39 on the inner surface of the bush. Each spindle 24 extends as a close rotational fit through the bushes in the associated link 22, roller 25 and links 23, 21, the links and roller being held in position on the spindle by a hitch pin 40.

Each hitch pin 40 is secured in a transverse bore 41 in the outer end of the associated spindle 24. As shown in Fig. 3, the outer end of the spindle is formed with an annular groove 42 on its outer surface, the bore 41 opening into the groove, and each hitch pin 40 has two limbs 43, 44 connected by a bight portion 45, the limb 43 being straight and the limb 44 having a curved portion 46 adapted to engage as a snap fit in the groove 42 when the limb 43 is inserted in the bore 41. The bight portion 45 forms a handle which facilitates withdrawal of the pin to permit removal of the links 21, 22, 23 and the roller 25 from the spindle when it is necessary to dismantle the chain.

Each hitch pin 40 can of course be replaced by a simple pin, a cotter pin, a spring retaining ring or other suitable device which can easily be detached from the spindle.

As shown in Fig. 4, each hitch pin 40 holds the associated link 21 in abutting contact with the link 23 which is in turn held in abutting contact with the adjacent projecting end of the bush 38 on the roller. The opposite end of the bush 38 on the roller is in abutting contact with the link 22 which is in turn in abutting contact with the link 20. The annular recesses 39 in the ends of the bush 38 on the roller thus co-operate with the spindle and the adjacent links to form annular chambers which open directly into the annular space between the spindle and the bush 38, and into the annular space between the spindle and the bush 32 or 33 in the adjacent link.

The spindles 24 are made of metal and the bushes are made of a low friction material, such as for example RULON, so that no lubrication is required between the spindle and the inner surfaces of the bushes forming cylindrical bearing surfaces on the links and roller. The ends of the bush 38 on the roller, which project beyond the body of the roller, also provide radial bearing surfaces in sliding contact with the adjacent links 22, 23.

Each spindle 24 is provided with an axial bore 50 and radial bores 51 which connect the axial bore 50 with the interface between the spindle and the bush 38 on the roller. The bore 50 is closed at its inner end and opens through the outer end of the spindle to permit application of a nozzle 52 for supply of cleaning liquid to the bore 50.

Each of the links 20 is fitted with a slat support bracket 55 formed by a plate, one edge of the bracket 55 being welded to the side of the link facing the slat with the bracket extending inwardly perpendicular to the side of the link. Similarly each of the links 22 is fitted with a slat support bracket 56 formed by a plate, one edge of the bracket 56 being welded to the side of the link facing the slat with the bracket extending perpendicular to the side of the link. The brackets 55, 56 have been omitted from Fig. 4.

The side chains 10, 11 each have an equal number of links and are offset longitudinally relative to one another by the length of a linl: so that each slat support bracket 55 on a link 20 of each chain is directly opposite a slat support bracket 56 on a link 22 of the other chain. Each slat 14 is mounted on the side chains with one end of the metal plate 1 6 Ot the slat welded to the bracket 55 on a link 26 of one chain and the opposite end of the metal plate 1 6 welded to the bracket 56 on a link 22 of the other chain. Each slat assembly consisting of a slat and links 20, 22 is thus reversed with respect to the adjacent slat assemblies so that the bushes 32 on the link 22 of each slat assembly are mounted on the spindles attached to the links 20 on the adjacent slat assemblies.

In accordance with the present invention, the bearing surfaces between each spindle 24 and roller 25 in the side chains 10, 11 can be cleaned without dismantling the chains by supplying cleaning liquid under pressure to nozzle 52 and applying the nozzle to the open end of the axial bore 50 in the spindle. The open ends of the axial bores 50 are on the outboard sides of the chains relative to the remainder of the conveyor and are thus readily accessible. Liquid forced into each axial bore 50 will flow through the bores 51 and into the clearance gap between the spindle and the bush 38. The liquid will flow across the bearing surfaces on the spindle and bush 38 and into the annular chambers formed by the recesses 39 at the ends of the bush 38.

The liquid in these chambers will be pressurised by the flow of incoming liquid, and part of the liquid will be forced between the spindle and the bushes 32, 33 in the links 22, 23, thereby cleaning the bearing surfaces on these components. The remainder of the liquid from the chambers formed by the recesses 39 will flow radially outwards between the ends of the bush 38 and the adjacent links 22, 23.

The cleaning liquid preferably has a bacteriocidal and/or a bacteriostatic and/or a detergent action, and can conveniently be any of the washing detergent liquids in use in the dairy industry.

The external surfaces of the chains and slats can be cleaned by clean-in-place equipment.

The conveyor can readily be dismantled when necessary for further cleaning. As shown in Fig. 5, one end of each slat 14 is attached to a link 20 fitted with two transverse spindles 24 engaged in bearing apertures formed by the bushes in links 22, 23, 21 which are arranged outboard of the link 20 attached to the slat, and the other end of each slat 14 is attached to a link 22 provided with two bearing apertures formed by the bushes therein, the links 20 of the associated chain being arranged inboard of the link 22 and having two spindles 24 engaged in the bearing apertures in the link 22 attached to the other end of the slat.Each slat assembly consisting of the slat 1 4 fitted with a link 20 at one end and a link 22 at the other end can thus readily be removed from the remainder of the conveyor for cleaning purposes by removing the hitch pins from the spindles identified by the references 24a, 24b, 24c, 24d, 24e, 24f in Fig. 5, and sliding the links 21a, 21b, 23a, and the rollers 25a, 25b off the spindles 24a, 24b, 24c, 24d. The slat assembly may then be moved axially in the direction of the arrow A in Fig. 5 to withdraw the spindles 24e, 24f from the bearing apertures formed by the bushes in the links and rollers pivotally mounted thereon, and to slide the link 22 on the slat off the spindles 24b, 24c. The slat assembly can be replaced by reversing the procedure.

The side chain shown in Fig. 8 has components which are similar in construction and operation to the components of the chain of Figs. 4 and 5, and to facilitate the description of the chain of Fig. 8 its components are identified by the reference numerals of the corresponding components of the chain of Figs. 4 and 5 with the addition of 100.

The chain of Fig. 8 comprises links 120, 121, 122, 123, spindles 124, and rollers 1 25 similar in construction and operation to the links 20, 21, 22, 23, spindles 24 and rollers 25 of the chain of Figs. 4 and 5. The slat support brackets 1 55 in the chain of Fig.

8 are however formed integral with the links 120, and the slat support brackets 1 56 are formed integral with the links 1 22. As shown in Figs. 6 and 7, each link 1 20 and bracket 1 55 are formed from a single flat metal plate, one end of which is shaped to form the link 1 20 and the other end of which is shaped to form the bracket 1 55. The centre portion of the flat metal plate is folded as shown in Fig.

7 so that the bracket 1 55 extends substantially perpendicular relative to the adjacent side of the link 1 20. Each link 122 and slat support bracket 1 56 are similarly formed by folding a metal plate of the shape shown in Fig. 6.

The two end portions of each of the links 1 20 and 1 21 are deformed out of the general plane of the link in the direction towards the adjacent link which is in overlapping relation- ship, as shown in Fig. 8. Thus the ends 1 60 of links 1 20 are each deformed in the direction towards the adjacent overlapping link 1 22 so as to make point or line contact with the link 1 22. The remainder of the overlapping portions of links 120, 1 22 are thus spaced apart and this facilitates cleaning by clean-in-place equipment. Similarly the ends 161 of links 121 are each deformed in the direction towards the adjacent overlapping link 1 23 so as to make point or line contact with link 123, the remainder of the overlapping portions of links 121 and 123 being spaced apart.

The roller 1 25 of the side chain of Fig. 8 is provided with a peripheral groove 1 25a to enable the side chain to be mounted on a guide rail (not shown) with the upper portion of the rail accommodated in the groove in the roller.

Claims

1. A method of cleaning bearing surfaces in apparatus comprising a spindle having a bearing surface thereon and a component rotatably mounted on said spindle, said component having a bearing surface in sliding contact with said bearing surface on the spindle without lubricating medium therebetween, wherein the spindle is provided with a bore which opens to the interface between said bearing surfaces, and cleaning liquid is forced under pressure into said bore so that the cleaning liquid flows through said bore to said interface and flows over the bearing surfaces.

2. A method ds claimed in claim 1, wherein said bore is open at one end thereof, and the cleaning liquid is supplied to the bore through a nozzle applied to the open end thel eot.

3. A method of cleaning bearing surfaces in a chain comprising a plurality of links pivotally connected to one another by transverse spindles and rollers rotatably mounted on at least some of said spindles, each roller having a bearing surface thereon and the associated spindle having a bearing surface in sliding contact with said bearing surface on the associated roller without lubricating medium therebetween, wherein the spindle is provided with a bore which opens to the interface between the bearing surfaces on the roller and spindle, and cleaning liquid is forced under pressure into said bore so that the cleaning liquid flows through said bore to said interface and flows over the bearing surfaces.

4. Apparatus having bearing surfaces adapted to be cleaned by the method of claim 2, said apparatus comprising a spindle having a bearing surface thereon, and a component rotatably mounted on said spindle, said com- ponent having a bearing surface in sliding contact with said bearing surface on the spindle without lubricating medium therebetween, wherein the spindle is provided with a bore which opens to the interface between said bearing surfaces, and one end of said bore is open and accessible for application of a nozzle thereto for supply of cleaning liquid under pressure to the bore the thereby to said interface between the bearing surfaces.

5. Apparatus as claimed in claim 4, wherein at least one of the components of the apparatus is fitted with a bush of low friction material providing one of said bearing surfaces.

6. A chain having bearing surfaces adapted to be cleaned by the method of claim 3, said chain comprising a plurality of links pivotally connected to one another by transverse spindles and rollers mounted on at least sorne of said spindles, each roller having a bearing surface thereon and the associated spindle having a bearing surface in sliding contact with said bearing surface on the roller without lubricating medium therebetween, wherein the spindle is provided with a bore which opens to the interface between the bearing surfaces on the roller and spindle, one end of the bore being open and accessible from one side of the chain for application of a nozzle thereto for supply of cleaning liquid under pressure to the bore and thereby to said interface between the bearing surfaces.

7. A chain as claimed in claim 6, wherein each roller comprises an annular body fitted with a bush of low friction material forrnir.g 2 cylindrical bearing surface which is in sliding engagement with the bearing surface on the spindle.

8. A chain as claimed in claim 7, in which, each roller is disposed between a pair of said links, wherein the ends of the bush project beyond the ends of the rollers body and film radial bearing surfaces adapted to engage the adjacent links.

9. A chain as claimed in claim 7, wherein each end of said bush co-operates with the spindle and the adjacent link to form an annular chamber, whereby, upon supply of cleaning liquid under pressure to the interface between the bearing surfaces, the liquid flows along the bearing surfaces into said chambers and forms therein reservoirs of cleaning liquid from which the liquid flows between the spindle and the links mounted thereon.

10. A chain as claimed in claim 6, wherein the links are fitted with bushes of low friction material forming bearing surfaces in engagement with the spindle.

11. A chain as claimed in claim 7, wherein each roller has side walls which are bevelled so that at least the major portions of the side walls are spaced from the adjacent links.

12. A chain as claimed in claim 6, in which two of the links connected by each spindle have the adjacent end portions thereof arranged alongside one another in overlapping relationship, wherein an end of at least one of the links is deformed out of the general plane of the link in the direction towards the other link, whereby the deformed end of the link makes contact with the other link and the remainder of the overlapping portions of the two links are spaced apart from one another.

1 3. An endless conveyor comprising two endless chains as claimed in any of claims 6-12 and a plurality of slats mounted on and extending between the chains, wherein the bores in the spindles of the chains each has an open end thereof facing outwards from the conveyor so as to be readily accessible for application of a nozzle thereto for supply of cleaning liquid under pressure.

14. A method of cleaning bearing surfaces in a chain as claimed in claim 3 and substantially as hereinbefore described with reference to Fig. 4 or Fig. 8 of the accompanying drawings.