GB2154533A - A cable driven belt conveyor - Google Patents

Abstract

Laser apparatus for ophthalmic surgery, comprises a slit lamp (1) with a lens system (2), an optical axis (3) and an operating laser (4) attached to the slit lamp. The laser beam (5) formed by the operating laser is reflected onto the optical axis (3) of the slit lamp. The laser beam (7) from an aiming laser (6) is also reflected onto the optical axis (3) of the slit lamp (1). The apparatus is provided with an adjustment means (8) for adjusting the focus of the laser beam (5) from the operating laser (4) independently of the focus (10) of the slit lamp and of the focus (11) of the aiming laser's laser beam, preferably to lie behind the latter as seen from the eyepiece (2<2>) of the slit lamp (1). <IMAGE>

Description

SPECIFICATION ConveyorE; and belts therefor The invention relates to conveyors and belts therefor, of the type in which the belt is both supported and frictionally driven by cables or ropes to convey material.

In such conveyors it is normal for the belt to be provided with (usually two) guideways on each side thereof in which the cables or ropes (hereafter referred to as cables) locate so that the cables and belt are positively located transversely relative to one another on both carrying (outward) and return (inward) runs of the belt. The guideways are generally formed by projections attached to or formed integrally with the surfaces of the belt to extend longitudinally therealong.

Among the difficulties encountered with such conveyors are that the provision of a set of projections on each side of the belt is costly and increases the volume required for storage when the belt is not in use (and for example wound on a drum), and the fact that the material carrying surface of the belt on the outward run forms the lower surface of the belt on the inward run can cause debris to fall from the belt and/or contamination of the cable locating guideways (with material being conveyed) possibly leading to cable damage.

Again it is necessary with known conveyors of this type for the belt driving and supporting cables to be moved away from the belt at the ends of the conveyor to permit the belt to run round a return drum, and then to arrange for the belt to re-engage with the cables on its other run. The know ways of disengaging the cables from the belt utilise pulleys carrying the cables through an angle and onto new paths extending away from the conveyor belt and thereafter, via further pulleys, back to the conveyor to re-engage with the belt for the return run. The life of an endless cable used in dynamic service is inversely proportional to the number of times it passes round a pulley and is bent during it operating cycle.Thus it would be clearly desirable to reduce the number of turns made by the cable in reversing its direction of motion, however this is not possible with the known conveyors due to the need to carry the cables away from the belt to prevent the cables interfering with the belt as the belt reverses direction.

It is an object of the present invention to provide a conveyor and belts therefor, which alleviate or overcome some or all of the above noted, and other, disadvantages of known conveyors.

Accordingly one aspect of the invention provides a cable driven belt conveyor comprising a belt having cable locating guideways for engaging with belt supporting and driving cables in the conveyor, the conveyor including means at each end thereof for twisting the belt after the belt has been disengaged from said cables and before the belt is reengaged with said cables such that the belt presents the same surface uppermost on both outward and inward runs of the conveyor.

Preferably, the belt twisting means twist the belt through 180 after disengagement from said ca bíes.

Each belt twisting means may comprise a number of spaced apart guides cooperating with the belt, the axis of said guides extending in different axial directions with respect to one another such that as the belt passes through them it is twisted through 180 . Advantageously at least some of said guides comprise pairs of rollers or other guide means mounted to contact each side of the belt.

The guides or at least some of them, may be driven to rotate at a speed corresponding to the belt speed.

A second aspect of the invention provides a belt for use in a conveyor embodying the invention, which belt is provided with cable locating guide ways on oniy one surface thereof; said guideways entending longitudinally of the belt and being located adjacent the edges of said one surface or at a position offset from the edges of said one surface towards the centre of the belt.

Two sets of cable locating guideways may be formed on said one surface thereof permitting the belt to cooperate with cables spaced at different distances apart on outward and inward runs of a conveyor on which the belt is used.

The guideways may be formed by cooperating pairs of ribs or projections formed to extend longitudinally along the belt on said one surface thereof or as recesses in said one surface of the belt.

That surface of the belt not provided with said guideways may have longitudinally extending projections located respectively at or near to the edges of the belt to serve to retain material carried by the belt.

A third aspect of the invention provides a conveyor system including a conveyor as noted above, in which system the conveyor belt is used to convey material on both inward and outward runs thereof.

Various embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 illustrates belts embodying the present invention, Figure 2 illustrates a belt embodying the present invention as it passes around an end run in a conveyor, Figure 3 illustrates schematically at A a conveyor embodying the present invention and at B the twisted path of the belt in part of that conveyor, Figure 4 illustrates schematically the head end of a conveyor embodying the present invention, Figures 5 and 6 illustrate respectively alternative arrangements of head and tail end layouts for a conveyor embodying the present invention, and Figures 7, 8, 9 and 10 illustrate operation ar arrangements of conveyors embodying the present invention.

Figure 1A shows a belt 20 embodying the invention to have a lower surface 21 on which are provided two longitudinally extending guideways 22 formed adjacent its edges. Each guideway 22 comprises a pair of projections 23 on surface 21. In use cables 24 which support and drive the belt locate in guideways 2Z and frictionally engage therein.

The other surface 25 of the belt 20 is provided with a pair of longitudinally extending projections 26 as shown.

The belt 20 is preferably formed of a rubber or rubber-like material which is reinforced to provide that the belt is, preferably, stiff laterally but flexible longitudinally. The reinforcement may be provided by fabric strips or steel straps embodied in the ma material of the belt however it is preferred that the reinforcement be provided by woven steel and fabric webbing .

The projections 23 and 26 on the lower and upper surfaces of the belt shown in Figure 1 are preferably formed integrally with the belt although it is envisaged that in certain circumstances they may be formed separately from the belt and then attached to the belt.

Figure 1 B illustrates an arrangement of the beit shown in Figure 1Amodifed to include second guideways 22' formed on the surface 21 of the belt. The second guideways 22' are, as with the first mentioned guideway, formed by two longitudinally extending ribs or projections. The guide ways 22 and 22' enable the beit to be used in conveyors in which the spacing of the cables on the outward and inward runs is different.

Figures 1C, 1D and 1E illustrate other modified forms of the belt 20. In Figure 1C the projections 26 and guideways 22 are located at the extreme edges of the belt. In Figure 1D the projections 26 are again located at the extreme edges of the belt but the guideways 22 have been moved towards the centre of the belt by an amount D.

In Figure 1E both the projections 26 and guide ways 22 are located closely adjacent the edge of the belt, however in this arrangement the height of the projections 26 has been considerably extended.

This form of belt is particuarly useful in an ar arrangement intended to carry free flowing granular material .

Figure 1 F illustrates how the belt shown in Figure 1A may be stacked or wound on a drum. It will be noted that in this arrangement the projections 26 locate within the guides 22 of the next outermost turn of the belt. In this way the stacking density of the belt is maximised.

A modification which may be made to the belts shown in Figure 1, particuarly that shown in Figure 1E, is illustrated in Figure 2. Difficulty may be encountered when using a belt having an extended retaining projection 26 as the belt travels around the end drum which it is mounted. Figure 2 shows this arrangement as the belt 20 passes around a drum 28. The projection 26 is shown to be corrugated or pleated at 27. These corrugations or pleats open out as the belt turns round drum 28 ai- lowing the reversal of the direction of the motion of the belt without significant stress being placed thereon.

Figure 3A illustrates schematically a conveyor ar arrangement including a belt such as is described with reference to Figures 1 and 2.

In the conveyor arrangement shown in Figure 3A the belt 20 passes around end drums or rollers 31 and 32 and is driven to move by cables 33 passing around pairs of cable wheels 34 and 35. It is to be noted from Figure 3 that the belt 20 is twisted through 180 whilst in the vicinity of the rollers 34 and 35 such that the same surface of the belt (surface 25) is uppermost for the top run of the conveyor and for the majority of the bottom run of the conveyor.

Figure 3B shows, in a perspective view, the twisting of the belt 20 as it travels in the direction of the arrow A from the end drum 32 shown in Figure 3A.

The way in which the belt is twisted will become clearer from the following description of a practical implemention of the invention made with reference to Figure 4 which illustrates the head end of a belt conveyor embodying the present invention. In Figure 4 there is shown at A a partial side elevation of the head end of the conveyor showing particularly the way in which the direction and motion of the belt is reversed and the first part of the twist is imparted to the belt; figure 4B is a partial side elevation iilustrating the way in which the direction of motion of the cables is reversed and how the twisting of the belt is completed. Figures 4C, D, E and F are sectional end views drawn on the lines CC, DD, EE and FF respectively of Figure 4B.

With reference now to Figure 4 the conveyor belt 400 with its uppermost sides 401 is driven in the conveyor by the cables 402. At the head end of the conveyor the direction of motion of the cables 402 is reversed by passing the cables around cable wheels 403 as shown. As can be seen the belt 400 extends past the cable wheels 403 and is carried over a series of guide rollers 404 to a head end drum 405 around which it passes. After passing around the head end drum the belt 400 passes beneath a guide roller 406 and then continues, in the reverse direction, towards the cable wheels 403. As the belt moves towards the cable wheels it enters a system of guides indicated generally at 407 which act to twist the belt through 180 ; some of these guides are shown in detail in Figures 4C, 4D, 4E and 4F.It will be noted that by the time the bottom run of the belt 400 passes between the cable wheels 403 it has been constrained by the guide system 407 to twist through 90 . That is to say as it passes between the cable wheels 403 the bottom run of the belt is effectively standing on edged - extending in a plane liying parallel to the planes of cable wheels. Thereafter the guide system 407 continues to twist the belt until it has been turned through 180 . At that stage the belt passes over a guide drum 408 and is carried down by means of guide rollers (not shown) to re-engage with the cables 402.

Figure 4C illustrates the "centre section" of the twist guide system 407. As can be seen this portion of the system comprises a frame 450 having top and bottom cross-pieces 451 and side arms 452. The cross-pieces 451 carry the ends of axles 455 and 456 on which are located pulley wheels 457 and 458 shaped as shown to conform to the shape of the guideways 459 and projections 460 respectively formed on the belt 400. It is especially to be noted that the side arms 452 of the frame 450 lie within the cable wheels 403 about which the cables 402 pass as they reverse their direction of motion.

The other elements of the guide twist system 407 comprise, as can be seen from Figures 4D, 4E and 4F a circular member 470 on which is mounted the particular guide form 471, 472 and 473 used to constrain the path of motion of the belt 400. The guides 471 and 473 for example (as seen in Figures 4D and 4F) comprise axles 475 on which are mounted a pair of rollers 476 shaped to conform to the guide ways 459 in the belt 400.

Similarly the element 472 comprises an axle carrying rollers 477 shaped to conform to the top side 401 of the belt 400 (see Figure 4E).

Figure 5 illustrates various arrangements which may be utilised at the head end of the conveyor shown in Figure 3.

Figure 5A corresponds, in substance, with the arrangement shown in Figure 4 whilst Figure 5B illustrates an alternative to that arrangement in which the belt 520 is twisted in the opposite sense as it leaves the end roller 532. A particular advantage of the arrangement shown in Figure 5A is that the final guide roller 599 over which the belt passes may also be used to locate the cable 534 in the guide-ways as the cable leaves the cable wheel 532. Thus in the arrangement of Figure 5B belt 520 passes over the guide roller 533 on leaving the end roller 532, then between pairs of guide rollers until it is turned through 1800 and then passes beneath a guide roller (not shown) to begin its return run.

Figure 5C shows an alternative arrangement somewhat similar to that shown in Figure 5B but in which the belt begins to be twisted as soon as it leaves the end drum 532.

Figure 6 illustrates two tail end layouts for the conveyor shown in Figure 3.

Figure 6A shows the cables wheels 31 to be mounted on a cable trolley 61 tensioned by means 62. In this arrangement the cable trolley also supports the framework 63 of the means used to twist the belt through 1800. With this arrangement that portion of the belt being twisted, and particularly the region of the belt extending substantially vertically, lies between the cable wheels 31 and moves therewith under the influence of the cable tensioning means.

As an alternative, for used when it is inconvenient to have the belt twisting means mounted on and movable with the rope trolley it is provided that, as illustrated in Figure 6B, the rope twisting means includes additional pairs of rollers (e.g. 42) spaced apart by a distance B allowing the rope trolley to move under the influence of the cable tensioning means 62 whilst at the same time ensuring that the belt runs vertically between the ca ble wheels 31 over the range of movements possible for the cable trolley.

It will be appreciated that a number of advantages stem from the particular configurations of belt and conveyor now proposed. Description will be made of some, particularly advantageous, arrangements which stem from this invention.

Firstly it will be noted that it is possible to use the bottom run of the conveyor now provided for the transport of material, and when this is done the top run of the conveyor may be used for weather protection. Such an arrangement is illustrated in Figure 7.

In the arrangements shown in Figure 7 conveyor is housed within side walls 71 extending substantially to the height of the upper run 72 of the conveyor. The upper run 72 of the conveyor acts to protect material on the lower run for example keeping it dry from rain. Rollers 73 may be provided (Figure 7A) to hold the upper run 72 of the conveyor belt 20 down in windy weather conditions. Alternatively as shown in Figure 7B it is possible to extend the side walls up and over edges of the top run of belt 20 as shown at 74.

Although not illustrated it will be appreciated that the conveyor now proposed may be utilised to carry material in different directions. Thus the top run may carry material out whilst the bottom run carries that material back in. Alternatively if the bottom run is being used to carry material in one direction the top run may be used, at the same time, to carry men and/or machinery in the other direction. Thus it is possible, for example in a mine to carry men into the mine whilst carrying material out of the mine and vice versa.

To illustrate the utility of using the bottom run of the conveyor for the carriage of materials Figure 8 illustrates ways in which material may be loaded onto that run.

In Figure 8A the side wall 71 is pierced at 80 and has passing through it means, for example a conveyor 81, carrying material to the bottom run 83 of the conveyor embodying the invention. Opposite the aperture 80 a guard 84 is provided on the inner wall which extends, as shown, to prevent material fed to the belt 20 overspilling.

The arrangement shown in Figure 8A may be modified as shown in Figure 8B where the conveyor 81 is substantially higher than the conveys embodying the invention. In this case the aperture 80 in the side wall 71 is pierced by a chute 86 to which material is fed from the conveyor 81.

Figure 8C shows an arrangement in which material is fed directly from above onto the bottom run of the conveyor. In this arrangement the upper run of the conveyor is completely shrouded by a guard 90, and two side walls 91 and 92 shaped as shown are provided to channel material deposited into a top chute 93 directly onto the bottom run of the conveyor. Although the arrangement shown in Figure 8C illustrates a "bifurcated" feed path (to either side of the bottom run of the conveyor) it will be appreciated that a chute may be provided directly to the top run of the conveyor.

The particular arrangement proposed for twisting the belt, as described above with reference to Figure 4, aids the removal of material from the bottom run of the conveyor embodying the present invention.

Figure 9 illustrates a way in which material may be removed therefrom in which it will be seen that the twisting means is arranged to twist the belt through approximately 900 - (ahead of the position at which the belt passes between the cable wheels) and thus tips from the belt 20 any material carried thereon. In this arrangement a chute 95 may be provided as shown. It should be noted that the chute is extended upwardly and away from the belt 20 as illustrated at 96 to ensure protection for the cable run, which at the stage is not in contact with the belt 20.

Finally Figure 10 illustrates that by extending the projections 26 on the uppermost, carrying, surface of belt 20 it is possible to ensure for the ready carriage of free flowing materials around bends in the conveyor line. The extended projections act to retain the material on the belt more readily than has heretofore been the case where the guideways 22 are provided as the sole means for retaining material on the belt.

It will be appreciated that a number of advantages stem from the provision of a conveyor belt embodying the present invention.

It is usual for cable driven conveyors to have cable grooves on each surface of the belt to allow the belt to return and still locate with the drive and support cables on the return run. Belts embodying the invention may be used in standard forms of conveyor, and simply fit into a standard conveyor (providing belt twisting means are also fitted) and the same cable locating projections on the top conveyor run may be used on the return cable run.

The provision of cable locating guideways on only one surface of the belt allows greater utilisation of the belt carrying surface area. Thus with the arrangements described it will be noted that the projections 26 may be formed at the extreme edges of the belt whilst the guideways 22 may be located some distance from those edges. Thus it is possible to provide for adequate support of the belt over its full width and make use of the full width of the belt up to the inside edges of the projections 26.

The provision of the cable guideways only on the undersurface of the belt prevents material being carried by the belt (coal, iron or, dirt etc.) contaminating those guideways. This overcomes a serious problem found in the conventional conveyors in which the cable locating guideways are provided on both belt surfaces.

The use of a single pair of projections on the carrying surface of the belt which are required solely for material location enables the belt line to travel round curved routes on tilted planes without material spillage.

The twisting of the belt such that it presents the same surface uppermost on both carrying and return runs means that all fines material remaining on the surface of the belt after discharging remain there. Thus these fines do not fall from the belt on its return run to accumulate beneath the conveyor.

As noted above the belt is preferably formed from a natural or synthetic rubber material with steel and synthetic fabric reinforcement to which is attached (or in which is formed) the longitudinal cable guideways. This particular construction allows the belt to be manipulated in transit by turning it through 1800 without damage. In the conventional arrangement where the belt incorporates rigid steel straps serious damage can occur if the belt is twisted through 1800.

Additionally, as noted with respect to Figure 9 the twisting means for turning the belt through 1800 can be used as a means for discharging material carried on the belt.

The twisting of the belt such that it presents the same surface uppermost on both carrying and return runs means that the top run may, as described, be used as a weather shield for the bottom, material carrying, run thereby eliminating the need to completely shroud the conveyor. The use of the bottom run for material transport lowers the centre of Gravity of the conveyor in use and increases the resistance of the conveyor to overturning in strong side winds. Thus shrouded conveyors embodying the invention may be smaller, overall, than known conveyors with consequent savings in manufacturing and installation (e.g. foundations) costs. The use of the top run for weather protection has the effect of rending that run more accessible for belt inspection and/or maintenance.

Thus it will be appreciated that the arrangements described above provide a new arrangement for belt conveyors having significant advantages over the arrangements known to date.

The ultimate life of the rope or cable used in the conveyor is dependent upon the life of any splices which are in the rope or cable. The life of a splice, in operation, is proportional to the number of pulleys and wheels about which it must pass.

Thus in the arrangement of the present invention the number of pulleys about which the cables must pass have been reduced from a minimum of six per cable with the known systems to two per cable. With this significant reduction in the number of pulleys traversed by the cables the splices are subject to less wear and therefor require less maintenance, the cables and ropes last longer making the conveyors more economically viable.

For example the extended life of the cables used in the present invention mean that shorter conveyor systems become economically possible whilst the longer, known, conveyors become more cost effective if provided with improvements embodying the present invention.

Claims (17)

1. A cable driven belt conveyor comprising a belt having cable locating guideways for engaging with belt supporting and driving cables in the conveyor, the conveyor including means at each end thereof for twisting the belt after the belt has been disengaged from said cables and before the belt is re-engaged with said cables, such that the belt presents the same surface uppermost on both outward and inward runs of the conveyor.

2. A conveyor as claimed in Claim 1, in which the belt twisting means twist the belt through 1800 after disengagement from said cables.

3. A conveyor according to Claim 1 or Claim 2, wherein each belt twisting means comprises a number of spaced apart guides cooperating with the belt, said guides extending in different axial directions with respect to one another such that as the belt passes through them it is twisted through 1800.

4. A conveyor according to Claim 3, wherein at least some of said guides comprise a pair of rollers or other guide means mounted to contact each side of the belt.

5. A conveyor as claimed in Claim 3 or Claim 4, wherein at least some of said guides are driven to rotate at a speed corresponding to the belt speed.

6. A conveyor according to any one of Claims 1 to 5, wherein said belt twisting means is located so as to cause the belt to lie in a plane extending normally of the axis of cable guide pulleys operable to reverse the direction of motion of the belt supporting and driving cables.

7. A belt for use in a conveyor as claimed in any Claims 1 to 6, which belt is provided with cable locating guideways on only one surface thereof.

8. A belt as claimed in Claim 7, wherein said guideways extend longitudinally of the belt and are located adjacent the edges of said one surface.

9. A belt as claimed in Claim 7, in which said guideways extend longitudinally of the belt and are located at a position offset from the edges of said one surface towards the centre of the belt.

10. A belt as claimed in Claim 7, having two sets of cable locating guideways formed on said one surface thereof permitting the belt to cooperate with cables spaced at different distances apart on outward and inward runs of a conveyor on which the belt is used.

11. A belt as claimed in any one of Claims 7 to 10, in which said guideways are formed by cooperating pairs of ribs or projections formed to extend longitudinally along the belt on said one surface thereof.

12. A belt as claimed in any one of Claims 7 to 10, in which said guideways are formed as recesses in said one surface of the belt.

13. A belt as claimed in any one of Claims 7 to 12, wherein that surface of the belt not provided with said guideways is provided with longitudinally extending projections located respectively at or near to the edges of the belt to serve to retain material carried by the belt.

14. A belt as claimed in Claim 13, wherein said longitudinally extending projections are pleated.

15. A conveyor system including a conveyor as claimed in any one of Claims 1 to 6, in which the belt of the conveyor is used to convey material on both inward and outward runs thereof.

16. A conveyor as claimed in Claim 1, and substantially as hereinbefore described with reference to the accompanying drawings.

17. A belt for a conveyor, as Claimed in Claim 7, and substantially as hereinbefore described with reference to the accompanying drawings.