BACKGROUND OF THE INVENTION

The invention relates to a roller belt which is closed in the circumferential direction and has overlapping belt edges. Along a conveying path, the belt is brought through several support roller stations, with the respective support rollerstations being provided with several belt support rollers which lie against the outer circumference of the roller belt.

German Offenlegungsschrift (printed, unexamined application) DE 36 20 906 discloses a roller belt which has the features of being closed in the circumferential direction, having overlapping belt edges, and being guided along a conveying paththrough a plurality of support roller stations which have respective belt support rollers in contact with the outer circumference of the roller belt. Additionally, only one common belt support roller is provided between the transporting and the returnfeed. It is known that roller belt conveyors do not always maintain their desired geometry which is necessary for optimum arrangement of the belt support rollers. In all prior art arrangements, the respective belt edge of the outwardly overlapping sideruns onto the edge of a belt support roller, thus always causing considerable damage to the belt and reducing its service life. If tension cables are additionally worked into the outer belt zones, i.e. its edge region, these tension cables are alsoaffected and finally wear through.

The most varied aids are employed to improve roller belt guidance in order to prevent or impede travelling of the belt. For example, guide and control rollers are employed or belt support rollers are placed at a camber (see, e.g. GermanOffenlegungsschrift 31 45 899).

However, all of these devices have the drawback that they require additional expenditures and that the resulting additional friction causes premature wear with increased driving power.

SUMMARY OF THE INVENTION

It is thus the object of the invention to improve a roller belt as described above regarding DE 36 20 906 so that it is able to freely move on its path in the circumferential direction within the belt support rollers without running on any edgesof the belt support rollers. In dependence on its load and on extraneous influences, such as sun, rain or the like, the belt will then always be able to take on its optimum position and opening along the way is to be avoided.

This is accomplished according to the invention in that the belt support rollers are arranged along the circumference of the roller belt in such a manner that, without contacting one another, they are superposed on one another. This measuremakes it possible for the mutually overlapping edges, i.e. the respectively radially outward edges of the roller belt, during rotation in the circumferential direction, to no longer run onto the edges of the next following belt support rollers. Damageto the belt edges is thus avoided, and the service life of the belt is extended. If the belt is twisted, the respective outer edge always moves directly onto the running surface of the next following belt support roller (wedge effect).

Appropriate modifications of the invention are defined in the dependent claims.

The subject matter of the invention can be employed with fixed belt support rollers as well as with support roller garlands even if they are based on a different number of belt support rollers; namely, an odd number (five, seven, nine) for fixedbelt support rollers and an even number (preferably six) for support roller garlands.

The belt support rollers are arranged in such a way that each belt support roller is overlapped at one end by the next following belt support roller, with all belt support rollers being arranged, for example, in the clockwise direction or all inthe opposite direction, depending on how the overlap of the belt edges is selected. In any case, the overlaps of belt support rollers and belt must be in the same direction. The oblique position of each following belt support roller causes the rollerbelt to continue to travel in the circumferential direction without giving any resistance to the respective belt edge. Twisting the belt roller in the opposite direction is also without problems since there will be no contact with the overlapping beltedge.

The configuration and arrangement of the belt support rollers according to the invention thus makes it possible for the belt roller to freely move in the circumferential direction without the use of constraining forces. Depending on conditions,the belt is able to select its optimum position by itself without encountering the danger that it will inadvertently open along the conveying path or that the belt edges place themselves against an outer edge of a belt roller with the resultingdestructive consequences. The invention is illustrated in the drawing and will now be described in detail. It is shown in:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 are schematic views of the roller belt according to the invention in various embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a roller belt conveyor which is held by means of upper and lower support roller garlands 1 and 2 in a support roller station not shown in detail. Each support roller garland 1, 2 is composed of three belt support rollers 3, 4, 5 and6, 7, 8, whose running faces 9 lie against the outer circumference 10 of the roller belt. In the region of belt support roller 4, which is arranged essentially horizontally, there is disposed the overlap region 11 where belt edges 12 and 13 lie on topof one another.

Belt support rollers 3 to 8 are each connected with one another by way of a single hinge point 14 which is arranged in such a way that belt support rollers 3 to 8 overlap one another. This overlap is produced by different distances a and b andprevents the belt edge 13 from running, for example, onto the edge 15 of the next following belt support roller 5. An imaginary axial extension of each running face 9 intersects the running face 9 of the next following support roller. In theillustrated embodiment, belt support rollers 3 to 8 are provided in an even number.

FIG. 2 shows a roller belt conveyor of the same structure as shown in FIG. 1 with overlapping belt edges 12, 13. Here, however, only five fixed belt support rollers 16, 17, 18, 19, 20 are provided, with the overlap region 11 here again beingprovided in the region of an approximately horizontally extending belt support roller 16. By superposition of belt support rollers 16 to 20 it is again prevented that belt edge 13 comes in contact with the edge 21 of the next following belt supportroller 17. If the roller belt is rotated clockwise, belt edge 13 runs directly onto the running face 22 of belt support roller 17 and is thus protected against damage.

FIG. 3 shows a roller belt equipped with six belt support rollers 23 to 28 which are arranged in such a manner that an approximately V-shaped support is formed int he upper and lower region of the roller belt while the lateral belt supportrollers 24 and 27 are arranged essentially vertically. Here again, belt support rollers 23 to 28 overlap one another so that the belt edge 13 is unable to abut at the edge 29 of the next following belt support roller 23. The overlap region 11 in thisexample is provided with an offset of about 30.degree. relative to the vertical and lies against belt support roller 28.

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