GB2122158A

GB2122158A - Twin-belt elevator

Info

Publication number: GB2122158A
Application number: GB08217554A
Authority: GB
Inventors: Wilfred Erwin Klinner; Andrew Charles Knight
Original assignee: National Research Development Corp UK
Current assignee: National Research Development Corp UK
Priority date: 1982-06-17
Filing date: 1982-06-17
Publication date: 1984-01-11

Abstract

A twin-belt elevator 8 comprises a load-supporting first belt 10 the operative run of which is formed and divided into a load-accepting region 16 and an elevating region 18 by a spring-loaded pivotally-mounted lower support roller 15 of a load- retaining second belt 12 positioned for co-operation with the elevating region 18 of the first belt. This co- operation is encouraged by having the load-retaining run 22 of the second belt shaped into a concave delivery region by a top support roller 24 of the first belt. The roller 15 is free to rise and fall and/or pivot. <IMAGE>

Description

SPECIFICATION Twin-belt elevator The present invention relates to elevators, and in particular to belt-type elevators providing the combination of a horizontal loading region with the facility to elevate at steep inclination to a discharge location located forwardly of the loading section.

This dual purpose combination is diffult to achieve using simple flat belts because of the problem of forming the necessary "concave" bend in the transition region of the belt from horizontal conveying to elevating in a manner which does not hinder the operation of the elevators. Thus, known proprietary dual purpose belt-type elevators, such as the Scholtz "Flexowell" (RTM) elevator, Numec's "Large Capacity Belting" and the Ace Vulcanising "Hywall" elevator, each comprise two flexible side walls set in from the edges of a cleated base belt so as to leave a narrow strip of base belt along the outside of each wall. This construction enables the concave bend in the base belt to be formed by mounting two narrow rollers above the belt so that they contact the upper surface of the two edge strips.In operation, the material to be elevated will be wholly contained between the two flexible side walls.

Without the side walls, the material would tend to spill into the side regions of the elevator and foul on the rollers.

It is an object of the present invention to provide a dual purpose belt-type elevator of comparable or better performance than those currently available, but by a simpler and therefore cheaper means.

According to the present invention, a twin-belt elevator comprises a load-supporting first belt having an elevating region which co-operates with the elevating region of a load-retaining second belt to convey the load to a discharge location position forwardly of the load-accepting region of the first belt, the operative run of the first belt being formed and divided into said elevating region and said load-accepting region by a lower support roller means of the second belt.

The term "roller means" in this context is to be broadly interpreted as uncluding any rotary or number of devices extending or spaced across the width of either belt to provide a roller type support for the belt.

A twin-belt elevator for conveying the letters and packets over a C-shaped path has been proposed in French Patent Specification 647597.

However, this earlier document neither suggests nor discloses the concept of using a twin-belt elevator for discharging to a location positioned forwardly of the load-accepting region even though this will be the desired elevator configuration in the vast majority of cases. It is significant too, that up to now, no such arrangement had been proposed during the fifty years or so since the French Patent Specification was published.

The French device is also defficient in other respects. For example, the belt-supporting roller defining the entrance to the elevating section has only a limited degree of freedom of movement.

This means that changes in the load being conveyed towards the elevating section will often result in a significant amount of roller displacement along the load-accepting belt away from the intended position of the roller. This in turn will lead to generally undesirable variations in the performance characteristics of the elevator.

This general lack of precision is aggravated by the use of a slack length of the load-retaining belt to control the passage of the load towards the elevating section.

Returning now to the elevator of the present invention, according to a preferred feature, the roller means is carried on a pivotally-mounted support on which it is spring-loaded towards the adjacent region of the first belt. Providing the roller means with two degrees of freedom in this way reduces the tendency for the roller means to be displaced along the first belt in response to a change load on the belt. Thus the division between the load-accepting and elevating regions of the first belt is maintained as constant as possible and as a result variations in the performance characteristics of the elevator with changing load are reduced.

Conveniently, the second belt is kept fairly taught around the roller means so that the entrance to the elevating section of the elevator is accurately defined by the position of the roller means. This enables the advantage of having a spring-loaded roller means to be exploited to the full.

Conveniently, the roller means comprises a relatively large diameter roller, or two or more rollers, arranged to shape the operative run of the first belt gradually in the region of directional change.

Where two or more rollers are used, these may, if desired, be mounted on a frame which is itself pivotally attached to the pivotally-mounted support. In a variation of this latter arrangement, only the frame pivots.

Conveniently the spring loading of the roller means is adjustable, a single adjustment changing the tension of both belts.

Preferably, the two belts are supported on as few rollers as convenient so as to encourage the belts to self-tension and self-adjust. This enables the belts to accommodate, compact and sandwich the conveyed material. In addition, it allows the elevator to be constructed as a relatively lightweight device.

Preferably, the load-retaining run of the second belt is guided about a top support roller of the first belt so as to shape said load-retaining run into a concave delivery region which encourages good co-operation between the second belt and the elevating region of the first belt and ensures that the material being conveyed is firmly gripped.

In a preferred embodiment, the inclination of the elevating and load retaining regions of the belts is adjustable, so that the conveyor can, without modification, offer horizontal conveying plus elevating at a range of angles.

According to a preferred feature, the second belt can overhang the top end of the first belt to some extent so as to predetermine the trajectory of discharge of material from the elevator.

It will be appreciated that the first and/or second belts may each be fiat or cleated as desired. Conveniently, both belts are cleated belts having the cleating spanning different transverse regions of the two belts so that marginal speed differences between the two belts will not cause interference between the cleats at the elevating region of the elevator nor prevent a degree of troughing from being achieved.

Conveniently, the two belts are of the same or roughly the same width.

Conveniently, the elevator includes troughing means effective to impart a trough-like shape to the elevating region of the elevator.

Conveniently, the elevator includes spillage prevention means arranged to flank or surround the first and second belts at the elevating region of the elevator to discourage spillage of conveyed material from this region.

In one embodiment, the elevator includes spillage prevention means arranged to flank or surround the first and second belts at the elevating region of the elevator to discourage spillage of conveyed material at this region and also to support at least in part the two belts at this region in such a way as to impart a trough-like shape to the elevating regions of the elevator.

A convenient spillage means, which can also serve as the main structural member, is a tube or other hollow section surrounding or substantially surrounding the first and second belts at the elevating region.

Conveniently, the elevating region of the first belt leads to an extension region provided either by the first belt or by a third belt.

Conviently, the inclination of the extension region is adjustable.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a partially diagrammatic side view of an elevator according to the present invention; Figure 2 shows a similar view of an alternative embodiment; and Figure 3 shows a cross section of a modified belt arrangement for use in either embodiment.

Thus referring first to Figure 1 of the drawings, a dual purpose elevator 8 according to the present invention comprises first and second belts 10, 1 2 co-operating over an elevating section 14 as shown. To this end, the belt supporting roller 1 5 at the bottom of upper belt 12 is so positioned as to shape the topmost run of lower belt 10 so as to divide this run into a load accepting region 1 6 and an elevating region 1 8. Similarly, the load retaining run 22 of upper belt 12 is slightly deformed near the delivery region by the intrusion of the top support roller 24 for belt 10 so as to encourage a proper co-operation between the two belts over the elevating section 14 and to compact the crop stream finally immediately prior to delivery.

The belt supporting arrangement is completed by idling rollers 26, 28 for belt 10 and by a top roller 30 for belt 1 2. It is an advantage of this design that there is no need for a rigid member to space apart the upper and lower rollers of the load retaining belt.

In operation, the top rollers 24, 30 provide the drives for the two belts, and conveniently they comprise identical diameter rollers driven at the same speed from a common power source (not shown).

In practice, the load accepting region 1 6 of belt 10 may receive its load 32 in one of a number of ways e.g. from a hopper (not shown). In this latter case, to reduce the risk of losses, the hopper arrangement would preferably be such as to prevent material from being deposited right out to the edges of the belt.

In a modification (not shown), troughing means can be incorporated along the elevating region 1 8 of belt 10 so as further to reduce the possibility of losses. Alternatively or additionally, closely fitting vertical side plates covering the interface of belts 10 and 12 along the full length of the elevating section 14 may be provided to contribute to the prevention of spillage of conveyed material at the sides. If the side plates are inclined towards each other along their length at their lower edges, they will also serve the purpose of giving the upwardly inclined belt regions 18 and 22 a trough shape and general support.

As shown in Figure 1 , the large diameter roller 1 5 at the lower end of belt 12 is spring loaded by a pair of compression springs 33 so as to hollow the belts 10, 1 2 to self-tension and self-adjust.

This enables the two belts to accommodate, compact and sandwich material reaching elevating section 14 from loading region 1 6. In more detail, each end of the roller support shaft 34 is anchored in an associated sleeve unit 36 which is urged along a respective rod 38 by the compression spring 33. At their lower ends, the rods 38 are secured to a common sleeve or pivot rings 40 allowing pivotal movement of the rods about an axle or pivot pins 42 secured relative to the elevator framework (not shown). The axle or pins 42 may be located wherever is convenient, provided that the loading by springs 33, either alone or in combination with additional springs (not shown), produces the required tensions in the belts 10, 12 and maintains the desired shape of the elevator.

If desired, the roller suspension linkage 33, 34, 36, 38 may be of alternative design so that tension springs can be used.

Preferably, roller 1 5 is of a width equal to or greater than the two belts 10, 12. The larger the diameter of the roller the more readily will bulky materials be accepted into the elevating region, even in circumstances of uneven feeding.

Where a more gradual change to the elevating section is desired, e.g. to accommodate specific materials, more than one roller joined together in the shape of a "bogey" may be used. One such arrangement is shown in Figure 2 where the bogey 44 replaces the single roller 1 5 of the earlier embodiment. As will be seen from the drawing, in the illustrated embodiment, bogey 44 comprises four relatively small diameter rollers 46 joined together by a common support means 48 in such a way as to define the desired curvature for the two belts. Support means 48 is pivotally connected at 50 so the sleeve unit 36 of the suspension linkage 33, 34, 36, 38 already described with reference to the first embodiment of the invention.This pivoted bogey arrangement provides an additional degree of freedom at the intake region (acting on the principal of a sluice) and this assists in the acceptance of intermittent, severely fluctuating and bulky loads.

In operation of the elevators described above, as material arrives at the roller means provided by roller 1 5 or rollers 46, as the case may be, the roller means rides up over the material and sandwiches it between the two belts, springs 33 maintaining belt tension at all times. Thereafter, the material is trapped and elevated by the upwardly inclined regions 1 8, 22 of the belt, to be discharged at the top end of the elevator e.g. into a container (not shown).

As illustrated, the upper of the two drive rollers 30 can overhang the lower drive roller 24 to some extent. Not only does this allow the trajectory of material discharge to be predetermined but it also helps to maintain the sandwiching effect at the top of the elevator if and when large lumps of material cause the two belts to part at the lower end of the elevator.

For a given trajectory, the throw of the material can be altered by regulating the speed of the two belts.

In a modification, extra reach for delivering the conveyed material at relatively slow belt speeds can be achieved with the elevator 8 by incorporating additional rollers 52 and 54 and extending the lower belt run at the delivery end as shown by broken line 56 in the drawing.

If desired, optional extension 56 may also be pivoted about roller 34 to extend the vertical reach of the elevator. In a variation of this latter embodiment, roller 54 is driven instead of roller 24 and the linkage for rollers means 1 5, 44 is modified so that when the vertical reach of the elevator has been extended as above described, the elevating section 14 can be pivoted about roller 28 (to the left in Figures 1 and 2) to enable material delivery to be achieved to points located over the feed region of the elevator.

If desired, a separate cleated or uncleated belt unit of variable inclination and speed can be incoporated in place of the integral belt extension 56 to achieve a greater range of delivery of the conveyed material.

Changes in the direction of delivery can be achieved by incorporating instead an impellerthrower, optionally rotatable about a near vertical axis.

Dual purpose elevators according to the present invention are suitable for a wide range of materials, including cohesive materials. In operation, they tend to compact the conveyed material and this can be advantageous in certain cases where low density compressible material is being elevated in order to fill a container.

As already mentioned in the introductory portions of the application, the belts 1 0, 12 may, if desired, be provided with cleating spanning only part of the width of each belt in such a way as to prevent interference between the cleats should there be any relative movement between the two belts. One such arrangement is depicted in the cross section of Figure 3 which shows two such belts co-operating at the elevating section of the elevator. As will be seen from this Figure, in the illustrated embodiment, belt 12 is provided with cleats 58 spaced apart along a central region of the belt whereas belt 10 is provided with cleats 60 lying on either side of cleats 58 and spaced therefrom. Other suitable arrangements are also possible, of course.

Besides the advantages already mentioned, the elevator of the present invention also enables complete longitudinal fill of the conveying space to be achieved with some materials, regardless of elevating angle, as opposed to the intermittent fill achievable with known designs of belt (or bucket) elevators which are dependent on elevating angle and the angle of response to the material. Thus the present invention allows elevators to be constructed which will operate satisfactorily at virtually any desired angle of elevation.

In addition, the simplicity of design, together with minimal friction and slip of material, favour a low power requirement and quiet operation, while as already suggested, variable trajectory, range and direction of delivery can also be incorporated.

Moreover, unlike the flexible wall approach of existing dual purpose belt-type conveyors, where still more elaborate support means are required for wider belts, the principles incorporated in the twin-belt elevators of the present invention are suitable for any width of belt.

In an alternative method of operating the illustrated embodiments, instead of driving roller 24 (or 54) and roller 30, only one of these rollers is driven, the co-operation between the two belts over their elevating regions being adequate to move that one of the two belts which is not directly in contact with the driven roller.

This invention finds particular application in the transporting and loading of powder materials, granular materials e.g. seeds or grain, aggregate materials including gravel and coai, long and chopped fibrous materials and small unit loads.

Claims

1. A twin-belt elevator comprising a loadsupporting first belt having an elevating region which co-operates with the elevating region of a load-retaining second belt to convey the load to a discharge location positioned forwardly of the ioad-accepting region of the first belt, the operative run of the first belt being formed and divided into said elevating region and said loadaccepting region by a lower support roller means of the second belt.

2. An elevator as claimed in Claim 1 in which the roller means is carried on a pivotally-mounted support on which it is spring-loaded towards the adjacent region of the first belt.

3. An elevator as claimed in Claim 1 or Claim 2 in which the second belt is kept taught around the roller means so that the entrance to the elevating section of the elevator is accurately defined by the portion of the roller means.

4. An elevator as claimed in any preceding claim in which the roller means comprises a relatively large diameter roller.

5. An elevator as claimed in any of Claims 1 to 3 in which the roller means comprises two or more rollers arranged to shape the operative run of the first belt gradually in the region of directional change.

6. An elevator as claimed in Claim 5 when including the limitations of Claim 2 in which the two or more rollers are mounted on a frame which is itself pivotally attached to said pivotallymounted support.

7. An elevator as claimed in Claim 5 when including the limitations of Claim 2 in which the two or more rollers are mounted on a frame which comprises said pivotally-mounted support, which frame is pivotally mounted on a non-pivotting support.

8. An elevator as claimed in any preceding claim when including the limitations of Claim 2 in which the spring-loading of the roller means is adjustable, a single adjustment changing the tension of both belts.

9. An elevator as claimed in any preceding claim in which the two belts are supported on as few rollers as convenient so as to encourage the belts to self-tension and self-adjust.

1 0. An elevator as claimed in any preceding claim in which the load-retaining run of the second belt is guided about top support roller of the first belt so as to encourage said co-operation between the second belt and the elevating region of the first belt.

11. An elevator as claimed in any preceding claim in which the inclination of the elevating and load-retaining regions of the belts is adjustable to allow elevating at a range of angles.

12. An elevator as claimed in any preceding claim in which the second belt overhangs the upper end of the first belt so as to predetermine the trajectory of discharge of material from the elevator.

1 3. An elevator as claimed in any preceding claim in which the first and/or second belts are each flat or cleated as desired and preferably of the same or roughly the same width.

14. An elevator as claimed in any of Claims 1 to 12 in which the first and second belts are cleated belts having the cleating spanning different transverse regions of the two belts so that marginal speed differences between the two belts will not cause interference between the cleats at the elevating region of the elevator nor prevent a degree of troughing from being achieved.

15. An elevator as claimed in any preceding claim including troughing means effective to impart a trough-like shape to the elevating regions of the elevator.

1 6. An elevator as claimed in any preceding claim including spillage prevention means arranged to flank or surround the first and second belts at the elevating region of the elevator to discourage spillage of conveyed material from this region.

1 7. An elevator as claimed in any of Claims 1 to 1 5 including spillage prevention means arranged to flank or surround the first and second belts at the elevating region of the elevator to discourage spillage of conveyed material at this region and also to support at least in part the two belts at this region in such a way as to impart a troughlike shape to the elevating regions of the elevator.

18. An elevator as claimed in Claim 16 or Claim 1 7 in which the spillage prevention means is a tube or other hollow section surrounding or substantially surrounding the first and second belts at the elevating region.

1 9. An elevator as claimed in any preceding claim in which the elevating region of the first belt leads to an extension region provided either by the first belt or by a third belt.

20. An elevator as claimed in Claim 1 9 in which the inclination of the extension region is adjustable.

21. An elevator substantially as hereinbefore described with reference to and/or as illustrated in Figure 1, Figure 2 or Figure 3 of the accompanying drawings.