US3669238A

US3669238A - Conveyors

Info

Publication number: US3669238A
Application number: US71828A
Authority: US
Inventors: Hugh L Folkes; Graham F Devenish
Original assignee: Dunlop Holdings Ltd
Current assignee: Dunlop Holdings Ltd
Priority date: 1969-10-08
Filing date: 1970-09-14
Publication date: 1972-06-13
Anticipated expiration: 1989-06-13
Also published as: FR2064197A1; DE2049475A1; FR2064197B1; ES383949A1; AR198372A1; GB1324076A; ZA706321B; NL7014498A

Abstract

The invention relates to guides for maintaining conveyor belts in the desired path when travelling through a bend, for example at the bottom, or top, of an inclined conveyor. The guides act on the load carrying surface of the conveyor for concave bends and on the lower surface of the belt for converse bends. The guides can comprise various forms of static members, auxiliary belts or endless chains.

Description

United States Patent Folkes et al. [4 June 13, 1972 [54] CONVEYORS [56] References Cited [72] Inventors: Hugh L. Folkes, St. Leonardsmn-Sea; UNITED STATES PATENTS g m; Devemsh 3,422,947 1/1969 Kraft et al ..198/16 g 3,414,108 12/1968 Jackson et al. ..198/16 [73] Assignee: Dunlop Holdings Limited, London, En- 756,600 1904 dge H /1 X gland 2,563,184 8/1951 Naylor 198/165 2,642,178 6/1953 Naylor 198/165 Ffledr p 14, 1970 2,578,592 12 1951 Pile ..198/137 [21] AppL NOJ 71,828 3,575,283 4/1971 Curran 198/202 Primary Examiner-Richard E. Aegerter 30 Foreign Application priority Data Assistant Examiner-Hadd S. Lane Att0rney-Stevens, Davis, Miller & Mosher Oct. 8, 1969 Great Britain ..49,340/69 [57] ABSTRACT [52] U.S.Cl ..l98/l6, l98/137 The invention felates to guides formaimaining conveyor belts [51] f Cl 9/12 in the desired path when travelling through a bend, for exam- [53] Field of Search 198/16-18, 4l, 1 at the bottom, or top, f an i li conveyor The guides 162, 165, 271/63 act on the load carrying surface of the conveyor for concave DIG A bends and on the lower surface of the belt for converse bends.

The guides can comprise various forms of static members, auxiliary belts or endless chains.

3 Claims, 11 Drawing Figures PATENTEDJUM 1 3 I972 13. 669.238 sum ear 4 PATENTEDJUN 131972 3.669.238

SHEET u or 4 ooo CONVEYORS This invention relates to conveyors, particularly but not exclusively passenger conveyors, of the type comprising a belt for carrying a load, and which conveys the load between two vertically spaced levels, such as two floors of a departmental store or warehouse.

The invention is particularly concerned with guide means for guidance of the conveyor when it travels in an arcuate path, for example at the top, or bottom, of the conveyor.

According to the present invention, a conveyor comprises; a belt having inner and outer surfaces at least one of which surfaces provides a load-carrying surface; drive means for the belt; support means for the belt whereby the belt follows a path including at least one arcuate portion; and guide means positioned at the arcuate portion and acting on one of the surfaces of the belt to maintain the belt in a predetermined path at the arcuate portion.

The arcuate portion may be convex or concave, viewed in a plane parallel to the length of the belt and normal to the belt surfaces. The conveyor may include both concave and convex portions, and guide means may be provided for either of the concave or convex portions or for both concave and convex portions.

A belt as used for the conveyor may be of varying form, generally comprising an endless length, having an elastomeric composition with reinforcement embedded therein. A particular form of belt is one of elastomeric composition having one or more plies of tensile reinforcement, and also transverse reinforcement which imparts to the belt a substantial degree of transverse rigidity, while retaining longitudinal flexibility. At least one of the surfaces, in a passenger-carrying installation, is formed with a tread pattern of longitudinally extending ribs which co-operate with comb-assemblies at each end of the conveyor.

As as an alternative, the belt may comprise individual lengths flexibly connected.

The invention will be readily understood by the following description of certain embodiments, by way of example, in conjunction with the accompanying diagrammatic drawings, in which:

FIG. 1 is a side elevation of a conveyor;

FIGS. 2 and 3 illustrate one form of guide means for concave and convex arcuate portions respectively;

FIGS. 4 and 5 illustrate another form of guide means for concave and convex arcuate portions respectively;

FIG. 6 and 7 illustrate a further form of guide means for concave and convex arcuate portions respectively;

FIGS. 8 and 9 illustrate guide means using roller chains for concave arcuate portions; and

FIGS. 10 and 11 illustrate guide means using roller chains for convex arcuate portions.

As illustrated in FIG. 1, a conveyor comprises an endless belt 10 in the form of an elastomeric material having tensile reinforcement and transverse reinforcement giving substantial transverse rigidity to the belt. The belt is made endless in any convenient manner from a length of belting, for example by splicing the ends together.

The conveyor is shown extending between two vertically displaced levels, and has a load carrying run comprising a lower level portion 11, a concave portion 12, an inclined portion 13, a convex portion 14, and a top level portion 15, and a return run 16. The return run also has a concave and convex portion 17 and 18 respectively. Guide means 19 and 20 are positioned at the concave and

convex portions

12 and 14 respectively.

Not shown in FIG. 1 is the supporting structure for the conveyor, this being of conventional form. Pulleys 21 and 22 are provided, one at each end of the conveyor, pulley 22 being driven by an electric motor 23 through a driving belt 24.

Support means for the belt is provided along its two longitudinally extending side edges throughout the length of the passenger-carrying runs in the form of edge rollers positioned to engage the underside of the belt, i.e. the inner surface thereof at the side edges only of the belt. The rollers are located at 6 inch intervals along the length of the belt and although the belt is unsupported between its side edges throughout the major part of the length of the passenger-carrying runs, its transverse rigidity is sufficient for its troughing between the side edges to be negligible, and the belt provides smooth and secure support for passengers carried thereon.

As a result of the drive imparted to the belt by the drive pulleys, the belt tends in use to lift from its edge support rollers in the concave portion of its travel. First guide means acting on the outer, load carrying surface of the belt in the region of the side edges only thereof is located in the concave portion and provides substantially continuous guidance for the belt over an extended portion of the belts path and resists the tendency of the belt to lift from the support rollers.

FIG. 2 illustrates in more detail one form of the guide means 19. The guide means comprises two curved air distribution members 30, one for each belt edge, shaped to conform to the desired configuration of the belt 10, in the concave portion of its travel and to cooperate with flat, unribbed portions of the belt at each side edge thereof. The air distribution members, one at each side edge of the belt are connected to a supply of compressed air for example by tube 31. The members 30 have surface portions 32 formed from a porous material which allows the air to escape from the curved surfaces of the blocks which confront the side edges of the belt. The steady flow of air from the distribution blocks, and its escape from between the blocks and the belt edges offers resistance to the belts tendency to lift in the concave portion, andthereby causes the belt smoothly to change direction.

The steady current of air flowing between the distribution members 30 and the belt edges provides a film which lubricates the belt in relation to its movement past the members while maintaining the desired guidance and hold-down effect. Thus the belt 10 experiences very low resistance to its travel past the members 30.

FIG. 3 illustrates one form of the guide means 20, which is substantially the same as the arrangement illustrated in FIG. 2, except that the distribution members 30 are curved in the opposite direction to act on the inner surface of the belt 10.

As an alternative, instead of the surface portions 32 being of porous material, they can be in the form of hollow manifolds with air release valves positioned at closely spaced intervals over the surface. The valves may be controlled by balls projecting from the outlets of the valves, the balls engaged by the belt edges. As a further alternative, the porous surface 32 may be replaced by magnets and corresponding strips of magnetic material extend along each side of the belt. The magnets, and the magnetic strips, are magnetized so that magnetic repulsion occurs, the magnetic repulsion maintaining a clearance between the guide means 19 and 20 and the belt 10.

I The strips of magnetized material provided on the guide blocks and on the belt edges may be of a flexible polymeric material such as a natural rubber composition having uniformly distributed therein a magnetizable material such as barium ferrite. Such a strip can be magnetized so that one pole is constituted by one longitudinally extending major surface of the strip and the other pole by the other major surface of the strip.

Other magnetic materials may be incorporated in the magnetic strips described above instead of, or in addition to barium ferrite. Such materials include strontium ferrite and lead ferrite, but barium ferrite is the preferred material. These materials are compounded with a suitable flexible polymeric material, foe example natural rubber or polyvinyl chloride, which is then formed into a sheet and subjected to a strong magnetic field. If the polymeric material is of the kind which requires curing it may be subjected to the strong magnetic field to affect magnetization either before or after curing. Suitable flexible polymeric materials which do not require curing include sulfonated chlorinated polythene. The products have a high magnetic coercivity associated with a comparatively low density. It is to be understood that the strips of magnetized material on the guide blocks need not be flexible and may be of a sintered magnetic material, or a sintered composition in which a magnetic material is dispersed.

In the arrangements illustrated in FIGS. 4 and 5, the guide means for the belt is constituted by auxiliary belts 35 one for each side edge of the main belt 10 in the concave and convex portions of its travel.

Each auxiliary belt 35 is guided around a pair of end pulleys 36 and a series of rollers 37 is provided for engagement with the inner surface of each auxiliary belt on the belt-engaging run thereof. The rollers are mounted so as to conform with the desired curved configuration of the main belt in the concave and convex portions of its travel.

Conventional belt tension control means is provided for each auxiliary belt and in use the auxiliary belts smoothly run around their end pulleys at a speed corresponding to the speed of the main belt and smoothly guide the main belt through the convex and concave portions of its travel.

The auxiliary belts are constructed so as to have a predetermined stiffness in the longitudinal direction which is sufficient for the guidance provided by the rollers to be substantially uniformly distributed along the concave and convex portions of the path of the main belt, but at the same time permits the auxiliary belts to pass around the end pulleys 36.

In further arrangements illustrated in FIGS. 6 and 7, and similar to the embodiment illustrated in FIGS. 4 and 5, the rollers are replaced by curved guide blocks 40. The form of the guide blocks 40 may vary. For example the guide blocks may carry magnetic means, and the inner surfaces of each auxiliary belt 35 is then provided with an endless strip of magnetic material to co-operate therewith. The polarity of the magnetic means on the guide block and of the magnetized strip of the inner surface of the auxiliary belt is such that magnetic repulsion is set up therebetween.

The magnetic means on each guide block is constituted by a strip of polymeric material for example natural rubber or poly(vinyl chloride), having a magnetizable material distributed therein. The magnetizable material is preferably barium ferrit, strontium ferrite or lead ferrite. The magnetized strip on the inner surface of each auxiliary belt is of a material similar to that of the magnetic means on the guide block. It is to be understood that the magnetic strip on each guide block need not be flexible and may for example be ofa sintered magnetizable material or of a sintered composition in which a magnetic material is dispersed. It is noteworthy that considerably less flexible magnetic strip material is required in the present embodiment in which each magnetic strip extends only around the inside surface of its respective auxiliary belt than in the embodiment described above, in which two strips are provided at each edge of the main belt throughout the length of the main belt.

Alternatively the guide blocks 40 may comprise air distribution blocks. A steady flow of air is supplied to each air distribution block, which is constructed to allow a distribution air outflor between the block and the auxiliary belt, and the air provides uniform guidance for both the main belt and the auxiliary belt, over an extended portion of the path of the main belt and at the same time effectively lubricates the confronting surfaces of the distribution block and the auxiliary belt. It will be noted that the inter-position of the auxiliary belts between the air distribution blocks and the edges of the main belt obviates the requirement for flat unribbed edges on the outer surfaces of the main passenger-carrying belt.

In a further alternative the guide blocks 40 have a curved profile for direct engagement with the inner surface of each auxiliary belt. The guide block is surfaced with polytetrafiuoroethylene or a similar low friction material and the corresponding inner surface of the auxiliary belt has a surface of a similar low friction material. The profile of the guide block is such as to cause the auxiliary belt to adopt the required curved configuration in relation to the main belt.

In another embodiment of the invention, as illustrated in FIGS. 8 and 10, the guide means 19 and 20 are in the form of endless chains 45, one mounted at each edge of the belt 10 in the concave and convex portions of the belts path. Each chain is of conventional drive chain construction, and is guided around two spaced-apart sprockets 46 so as to follow a path consisting of two flights. One flight of each chain is located adjacent the respective edge of the load-carrying surface of the belt for engagement therewith.

Thrust means in the from of a curved plate 47 located adjacent the belt-engaging flight of each chain and in rolling engagement with the rollers thereof causes the chain to assume a curved form as it passes the plate.

A tensioning device 48 for each chain is provided to engage the run thereof which is remote from the belt. The tensioning device comprises a curved plate adjustably mounted adjacent the said flight of the chain for rolling engagement with the rollers of the chain.

The sprockets 46 at each end of the chains runs are freely rotatable, and in use the chains 45 travel around the sprockets under the influence of the drive received by the chains from the belt 10. The curved plate thrust means 47, effectively causes the belt to assume the required curved profile in longitudinal cross-section and the chain provides substantially continuous guidance for the belt over an extended portion of the path of the belt.

The belt-engaging surfaces of the chains may be modified so as to secure certain advantages. For example, as illustrated in FIG. 9, the links of the chain may each be provided with a pair of right-angled brackets 49 one for attachment to each side thereof to increase the surface area over which the drive for the chain is transmitted thereto. Alternatively, the links of the chains may each have a curved belt-engaging surface so that in use the chain presents a smoothly curved surface to the respective surface of the belt.

Alternative forms of thrust means may be employed for engagement with the chains instead of the curved plate of the above embodiment. For example an assembly of rollers or an assembly of small sprockets may be used, the rollers or sprockets being arranged to cause the chains to present the required curved profile to the belt.

Further, the sprockets at each end of the chains path are not essential. Plates can be used instead, but the sprockets are inexpensive and serve to keep the chain in correct alignment with the belt edge.

In the embodiment illustrated in FIGS. 8 and 10 and described above, employing guide means comprising a chain at each belt edge, it will be noted that where a chain of conventional construction is employed, the shapes of the links are such that in theory, there will be a small gap between each link and the belt. In practice such a small gap would lead to very little rise in stress concentration in the belt and the length of the gap would be very considerably smaller than the space between successive rollers in the previously proposed system referred to above. For the purpose of the present invention such a chain thus provides substantially continuous guidance for the belt over an extended portion of its path.

It is to be understood that although in the above embodiments of the invention, the guide means 20 which is provided at the convex arcuate portion of the belts path acts on the inner surface of the belt in the region of the side edges only thereof, this guide means may extend across the full width of the belt. Such full width guidance has the added advantages of giving the belt full width support in this portion of its travel and thus enables the belt to negotiate satisfactorily a convex bend of smaller radius of curvature than is possible with edge support only. The advantage of the use of a smaller radius of curvature is that it reduces the overall space required for the conveyor installation. One particular arrangement is illustrated in FIG. 11 which shows the roller chain form of guide means, as in FIG. 10, the roller chains on each side of the belt being connected by plates 50, thus provided support and guidance across the full width of the belt 10. The plates 50 may be flat, or slightly curved viewed from one end.

Further, wherein the above embodiments a circulatable guide means, such as an auxiliary belt or a chain is employed, it is to be understood that the guide means may itself be connected to a source of motive power instead of being free running. Such use of the circulatable guide means in addition to the use of conventional drive means for the main belt reduces the tensile strength needed in the main belt.

Guide means, as in any of the embodiments described above, may also be provided at the concave and convex portions 17 and 18 of the return run.

Having now described our invention-what we claim is:

1. A conveyor comprising a belt, having inner and outer surfaces at least one of which surfaces provides a load-carrying surface; drive means for the belt; support means for the belt whereby the belt follows a path which, viewed in a direction parallel to the belt surfaces and normal to the length of the belt, includes at least one arcuate portion; and guide means positioned at the arcuate portion and acting on one of the surfaces of the belt to maintain the belt in a predetermined path at the arcuate portion, the guide means comprising two laterally spaced guide members, the guide members each acting on the belt at the side portion only, each guide member comprising an elongated arcuate member having a layer of magnetized material on the surface opposed to the belt, and a layer of magnetized material positioned along the belt in opposition to each guide member, whereby a magnetic repulsion occurs between the guide member and the belt.

2. A conveyor comprising a belt, having inner and outer surfaces at least one of which surfaces provides a load-carrying surface; drive means for the belt; support means for the belt whereby the belt follows a path which, viewed in a direction parallel to the belt surfaces and normal to the length of the belt, includes at least one arcuate portion; and guide means positioned at the arcuate portion and acting on one of the surfaces of the belt to maintain the belt in a predetermined path at the arcuate portion, the guide means comprising two laterally spaced guide members, the guide members each acting on the belt at the side portion only, each guide member being an auxiliary endless belt, the auxiliary belt supported at each end on a pulley, and at least one guide block positioned to engage the inner surface of the auxiliary belt over that portion which is acting on the load carrying belt, the guide block shaped to maintain the portion of the auxiliary belt in the desired arcuate configuration, the guide block comprising an air distribution member, and means for supplying pressurized air to the member, whereby, in operation, air escapes from a surface of the distribution member in opposition to the inner surface of the auxiliary belt, to maintain a clearance between the inner surface of the auxiliary belt and the surface of the guide block.

3. A conveyor comprising a belt, having inner and outer surfaces at least one of which surfaces provides a load-carrying surface; drive means for the belt; support means for the belt whereby the belt follows a path which, viewed in a direction parallel to the belt surfaces and normal to the length of the belt, includes at least one arcuate portion; and guide means positioned at the arcuate portion and acting on one of the surfaces of the belt to maintain the belt in a predetermined path at the arcuate portion, the guide means comprising two laterally spaced guide members, the guide members each acting on the belt at the side portion only, each guide member comprising an auxiliary endless belt, the auxiliary belt supported at each end on a pulley, and at least one guide block positioned to act upon the inner surface of the auxiliary belt over that portion which is acting on the load carrying belt, the guide block shaped to maintain the portion of the auxiliary belt in the desired arcuate configuration, and having a layer of magnetized material on its surface which is in opposition to the inner surface of the auxiliary belt, and a layer of magnetized material on the inner surface of the auxiliary belt, whereby magnetic repulsion occurs between the guide block and the auxiliary belt.