WO1997041051A1

WO1997041051A1 - Idler rolls

Info

Publication number: WO1997041051A1
Application number: PCT/EP1997/002190
Authority: WO
Inventors: Stefanus Petrus Bezuidenhout
Original assignee: Cason Engineering (Proprietary) Limited; Galgut, John
Priority date: 1996-04-29
Filing date: 1997-04-28
Publication date: 1997-11-06
Also published as: AU2888597A

Abstract

A training idler for a belt conveyor comprises a frame carrying the idler rolls, a cross-member and a carrier pin carried by the cross-member on which the frame is itself carried. The axis of the pin is arranged horizontally parallel to the direction of belt travel and vertically at 25° to the direction of belt travel. The pin is journalled in a plastic bush carried by a metal bearing carrier. Adjustable stops are provided to limit the amount that the frame can swing about the axis of the pin.

Description

IDLER ROLLS This invention relates to belt conveyor idlers.

In an array of belt conveyor idlers, a number of the idlers are training idlers, i.e. idlers which guide a conveyor belt back to a centred position if for any reason it travels off its intended direction. The invention is concerned with such a training idler.

A widely used conveyor belt training idler comprises a roll carrying frame or base that is pivoted on a vertical pivot pin carried by a cross member and that carries a pair of side guide rolls. These side guide rolls are located so that should the conveyor belt drift off line, it will eventually engage one of the side guide rolls and cause the frame to pivot appropriately so that the idler rolls are skewed relative to a line normal to the centre line of the belt. As the belt traverses the skewed idler rolls, they urge the displaced belt to return to the conveyor centre line. Once this occurs, the idler rolls are urged to return to the proper alignment.

Although this arrangement is quite successful, in practice it suffers from a number of disadvantages. First, the belt must drift off its centre line by quite a significant amount before it engages the side guide rolls. This has the effect that there is often spillage of the material being carried by the conveyor belt. Second, as a result of the edges of the conveyor belt engaging the side guide rolls there is a problem that the edge of the belt is often torn or otherwise damaged by the side guide rolls against which it must act quite firmly to pivot the idler the appropriate amount as aforesaid. Third, the frame must be carried by a thrust bearing with the disadvantages mentioned below.

Another known training idler for a return belt comprises a pair of aligned idler rolls arranged as aforesaid but canted through about 30° to the vertical. This training idler was used only on the return run of the belt conveyor. It had the disadvantage that the frame must be supported on a rotary thrust bearing, which in use will often jammed solid because of the in- gress of dirt and dust. The carrying of the frame on a thrust bearing also has a problem in that there is a slow reaction time to the belt moving off centre. This delayed the training movement of the frame. This arrangement has not been successful in practice and indeed as far as we know is no longer being sold and has not been sold for many years.

According to one aspect of the present invention there is provided a training idler comprising a frame carrying the idler rolls, there being a carrier pin on which the frame is itself carried, the axis of the pin being arranged horizontally parallel to the direction of belt travel and vertically at less than 45°, con¬ veniently between 15° and 35° and more conveniently at between 20° to 30° and preferably 25° to the direction of belt travel. There is preferably a bearing between the roll frame and the pin. This may be a bush, prefer¬ ably a plastics bush. The plastics bush may comprise Vesconite^®, high density polypropylene or other ultra high molecular weight polyethylene. Alternatively the bush may be a bronze bush. In this latter case bronze washers may be provided to take up thrust forces.

Stops are preferably provided to limit the amount that the frame can swing about the axis of the pin. Preferably the frame is limited to a side tilt of 7° on each side of the vertical and a forward tilt of 3,5° from the vertical. The stops are preferably adjust¬ able so as to vary the angles as aforesaid.

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

In the drawings:-

Figure 1 is a front view of a three roll troughing training idler of the invention, Figure 2 is a section on line 2 - 2 of Figure 1, Figure 3 is a perspective view of the training idler taken from one side, the rear and above, Figure 4 is a perspective view of the training idler taken from the same side, the front and below, Figure 5 is a front view of a modified training idler of the invention, Figure 6 is a front view of a modified, five roll, training idler for a wide conveyor belt, and Figure 7 is a section on line 7-7 of Figure 6. three roll troughing training idler of the invention.

Referring now to Figures 1 to 4, there is shown a troughing training idler 10 comprising a bent tubular roll frame 12 having a centre portion and two wing portions and having its ends closed off by stops 13 to prevent the ingress of dirt and dust. Three pairs of roll support lugs 16 are mounted respectively on these portions and project therefrom in the direction of movement of the conveyor belt (which is not shown) .

Rotatably mounted on the lugs 16 are a centre roll 18 and a pair of wing rolls 20 located to form a trough and to support thereon a conveyor belt (not shown) , which is travelling in the direction of arrow "B" in a manner known per se .

The frame 12 is carried on a cross member 22 in a manner which will be described below.

The cross member 22 is in the form of a substan- tially square section hollow bar, the ends of which are welded respectively to two angle mounting 24 that rest on and are bolted respectively to any form of longitudinal supports or beams (not shown) that run parallel to the conveyor belt. The cross member 22 extends in a direction transverse to the direction of belt travel and its upper and lower surfaces 26 and 28 are inclined to the horizontal by an angle of 25° . It carries a robust pivot pin 30.

The pivot pin 30 is located mid-way along the width of the cross-member 22 passing mid-way through the front and rear faces 32 and 34 of the cross member 22 and at right angles thereto. Its axis 30.1, consequently, extends in a horizontal direction parallel to the longitudinal direction of belt movement and vertically parallel to the upper and lower surfaces 26 and 28 of the cross-member 22, i.e. at an angle of 25° to the direction of belt movement, rising in the direction of movement of the belt. The pivot pin 30 is mounted in a high density polypropylene ("HDPE") bearing bush 36 (see Figure 2) which is carried in a tubular metal bearing carrier 38 that is welded to the walls 32 and 34 of the cross-member 22. The upper end of the pivot pin 30 passes through the frame 12 and is welded to the walls of the frame 12. A ring 40 is welded to the pin 30 adjacent the frame 12. The ring 40 rests on a washer 42 which in turn rests on the upper end of the bearing carrier 38. The lower end of the pin 30 projects beyond the end of the bearing carrier 38 and carries a pair of washers 44 which are held in position by a split pin 46 to hold the pivot pin 30 and frame 12 on the cross-member 22.

A pair of narrow "L" shaped plates 48 are welded to front face 32 of the cross-member equispaced on either side of the pivot pin 30 and within the path of the centre portion 12.1 of the frame 12. The legs 50 of the plates 48 extend forwardly. Adjustment stops in the form of bolts 52 are screwed into holes in the legs 50. The heads 54 of these bolts 52 are adjustable so that they can lie in the path of movement of the centre portion 12.1 as it pivots about the pivot pin 30. These bolts 52 thus serve as stops which prevent excessive pivoting of the frame, limiting the side tilt on either side of the vertical to 7° or vertical tilt to 3,5°. The bolts 52 can be adjusted vertically so as to vary the amount that the frame 12 can swing. The longer the bolts 52 protrude the less swinging movement of the frame 12 is permitted.

In use, the training idler 10 is mounted to support the conveyor belt. Should the belt tend to drift off its centre position it will climb up one or other of the wing rolls 20. The effect of the larger area of contact on that wing roll 20 will tend to swing the frame 12 about the pivot axis 30.1 in the direction of movement of the conveyor belt so that that wing roll dips downwardly as well as swings about the vertical axis. This movement of the frame 12 will tend to result in the belt seeking to climb the other wing roll which would now be more upwardly inclined than the first wing roll . In so doing the friction between the belt and the second wing roll will train the conveyor belt back to the centre position and at the same time will swing the frame 12 back to the position normal to the direction of movement of the conveyor belt which position it takes up when the belt is once more running in its centre position.

It will be seen that the frame is suspended close to the cross-member so that forces on the pivot pin are minimised.

Reference is now made to Figure 5 in which is shown a three roller troughing roll identical to that shown in Figures 1 to 4 save that there are suspended mounting brackets 56 carrying the cross-member. Inclined εtiffeners 58 are welded between extend from the brackets and the cross-member for improved strength.

A five roll trough training idler 60 for a wide belt of say 1900 mm width is shown in Figure 6. In this idler the frame 62 has five sections, viz a centre section 62.1, a pair of outermost sections 62.2 and 62.3 and two middle sections 62.4 and 62.5. Five pairs of lugs 64 are carried respectively by the sections and these carry respectively five rolls 66 which support a conveyor roller travelling in the direction of arrow B. The pairs of lugs 64 on the centre and outermost sections 62.1, 62.2 and 62.3 extend in the direction opposite to the belt travel. The lugs on the middle sections 62.4 and 62.5 extend in the direction of belt travel. This enables the adjacent lugs of adjacent pairs as well as the surfaces of the rolls to overlap so that there is substantially continuous support for the belt as is apparent from Figure 6.

The cross-member 66 is comprised by an angle member 68 that has the ends of its arms 70 and 72 welded to mounting plates 74 at its ends in such a way that the arm 72 opposite to the belt travel is inclined to the horizontal by an angle of 25°. At the centre of the arm 72 there is welded a pair of robust plates 76 and 78. A pivot pin 80 passes through openings in the plates 76 and 78 so that it, the pin 80, extends in the direction of the belt travel and vertically at an angle of 25° to the horizontal. The front end of the pin 80 is welded to a holding plate 82 which rests against the front of the front plate 76. A screw 84 (see Figure 6) passes through registering apertures in the plates 76 and 82 to hold them together. Between the plates 76 and 78 the pin 80 is rotatably carried in a HDPE bush 86 which fits into a steel bearing carrier 88 that is rotatable between the plates 76 and 78, there being washers 90 between the carrier 88 and the plates 76 and 78. This carrier 88 passes through the centre frame section 62.1 and is welded thereto to carry the frame 62.

Adjustment stops in the form of bolts 92 are screwed into holes in the arm 72. The heads 94 of these bolts 92 are adjustable so that they can lie in the path of movement of the centre portion 62.1 as it pivots about the pivot pin 80. These adjustment stops operate in the same manner as the adjustment stops 52 described above.

We have found that the training idlers of the invention are very sensitive to belt misalignment. As soon as the conveyor belt veers off the centre path there will be forces on one or other of the wing rolls tending to swing the roll frame about the axis of the pivot. Furthermore it is unnecessary to use side guide rollers which have the effect of damaging the conveyor belt. The arrangement is also much more sensitive than arrangements using thrust bearings and will, we have found, normally commence its reaction immediately once the belt moves off its centre line. Furthermore we have found that the pivot mounting of the frame is simple and economical to manufacture and is robust in use.

The training rolls are used at such intervals as the engineer installing the belt conveyor may desire. It may be every fifth idler roll, every twentieth idler roll or at any other interval as desired.

The invention is not limited to the precise cons¬ tructional details hereinbefore described and illus- trated in the drawings. For example the various dimensions mentioned may vary within the limitations that are apparent to those skilled in the art. The angle of inclination of the pivot pin may vary, preferably as discussed above, within limits for it to permit the movement of the kind mentioned and for it to be carried in a rotary bearing.

The frame can be made of materials different to those described above. For example the frame can com¬ prise hollow square section parts, channel shaped parts or angle iron parts.

Instead of HDPE, the plastic bush may comprise Vesconite^® or another ultra high molecular weight poly¬ ethylene or any other suitable plastics material . The longitudinal beams can be formed from angle iron, tubu¬ lar section, channel section or may comprise wire rope.

The training idlers of the invention can be fitted to the load carrying belts (usually as troughing training idlers as described) or the return belt (i.e comprising return training idlers) . The training idlers may be fitted with a single flat roll, preferably with rubber discs, two, three, four or five rolls. The rolls may be impact idler rolls.

Claims

1. A training idler comprising a frame for carrying idler rolls to support a conveyor belt, and being itself carried on a carrier pin to be capable of being pivoted about the axis of the pin, characterised in that the axis of the pin is arranged horizontally parallel to the direction of belt travel and vertically at an angle of less than 45° to the direction of belt travel rising in the direction of belt travel.

2. A training idler as claimed in claim 1 character¬ ised in that the axis of the pin is arranged vertically at an angle of between 15° and 35° and more conven¬ iently at between 20° to 30° and preferably 25°.

3. A training idler as claimed in claim 1 or claim 2 in which the frame is carried on a cross-member which carries the pin characterised by a bearing between the cross-member and the pin.

4. A training idler as claimed in claim 3 character¬ ised in that the bearing comprises a bush.

5. A training idler as claimed in claim 4 character¬ ised in that the bearing comprises a plastic bush carried in a steel bearing carrier that is welded to the cross-member.

6. A training idler as claimed in claim 1 or claim 2 in which the frame is carried on a cross-member which carries the pin characterised in that the cross-member carries a pair of robust plates between which the pin extends and in that frame is carried by a bearing surrounding the pin.

7. A training idler as claimed in claim 6 characterised in that the bearing comprises a bush.

8. A training idler as claimed in claim 7 character¬ ised in that the bearing comprises a plastic bush carried in a steel bearing carrier that is welded to the frame.

9. A training idler as claimed in any one of the preceding claims characterised by stops provided to limit the amount that the frame can swing about the axis of the pin.

10. A training idler as claimed in claim 9 character¬ ised in that the stops limit the movement of the frame to a side tilt of about 7° on each side of the vertical and a forward tilt of about 3,5° from the vertical.

11. A training idler as claimed in claim 9 or 10 characterised in that the stops are adjustable so as to vary the angles as aforesaid.