GB2140372A - Conveyor roller - Google Patents

Abstract

A roller for a roller conveyor (10) has a circular outer article-engaging surface (20) and a transversely extending through bore. A rotatable drive shaft (44) extends through the bore for rotating the roller. The bore in the roller is offset from the transverse centre of the roller to cause an eccentric rotation movement of the outer surface (20) of the roller. <IMAGE>

Description

SPECIFICATION Conveyor roller This invention relates to roller conveyors.

In many industries, conveyors are employed to convey articles, parts, and so forth, between various assembly or work stations. A typical conveyor is a so-called roller conveyor which includes a plurality of aligned rollers rotated by a drive means, such as a motordriven chain and sprocket assembly. One or more rollers are mounted on each of a series of aligned drive shafts to propel the articles, parts, or whatever, along the conveyor.

Due to tolerance build-up in the manufacture of each roller, it is difficult precisely to align the rollers along the plane of the conveyor to assure a flat surface along which the articles are conveyed. Thus, the upper surface of successive rollers can vary in height so that one or more rollers can be disposed slightly above the upper surface of the adjacent rollers. Furthermore, the conveyed articles frequently have projections or variations in the surface which engages the conveyor, such as flash on a casting. Such projections or protrusions can engage the roller which is raised slightly above the proceeding rollers and stop the article or part from making further progress along the conveyor.

The undesirable build-up of tolerances in rollers is a particular problem in friction-type roller conveyors in which each roller is constructed of a plurality of components, each of which has varying size tolerances. Particularly, each roller includes an inner roller which is mounted on and rotated by a drive shaft. An outer roller is concentrically mounted about the inner roller and is frictionally driven by the inner roller. When an article is stopped on the conveyor for a work operation, the weight of the article causes the outer roller to stall or slip with respect to the rotating inner roller until the article is again released for further movement along the conveyor. Due to the tolerance on each component of the friction roller, the overall roller size may vary by an amount which can lead to frequent stoppage of articles along the conveyor as noted above.

Thus, it would be desirable to provide a conveyor roller which overcomes the problems of previously devised conveyor rollers in which the aggregate of tolerances in the rollers results in an uneven article conveying surface which causes frequent and undesired stoppage of articles as the articles are being conveyed along the conveyor. It would also be desirable to provide a conveyor roller for a friction-type roller conveyor which is both inexpensive to manufacture and adaptable to many different applications.

The present invention is a roller for a roller conveyor. The conveyor roller has an outer article-engaging surface and a transversely extending through bore. A rotatable drive shaft extends through the transverse bore and rotates the roller. The transverse bore in the roller is offset from the centre of the roller to cause eccentric rotational movement of the outer article-engaging surface of the roller.

In a roller conveyor having a plurality of side-by-side aligned rollers, the angular orientation of the offset portions of adjacent rollers can be varied. In this manner, the outer article-engaging surface of each roller moves in an eccentric path upon rotation of the roller and will alternately engage and disengage the article being conveyed along the conveyor.

This movement of the article-engaging surfaces of the rollers overcomes any tolerance build-up that may be present in the rollers which previously has made it difficult to align precisely the rollers in the same plane and has resulted in frequent and inadvertent stoppage of the articles along the conveyor when the articles strike rollers having a large tolerance build-up.

The unique conveyor roller of the present invention overcomes these problems due to the eccentric mounting of the roller on its rotatable drive shaft. The angular position of the offset portions of each roller can be adjusted between successive rollers to insure that even those rollers which may be slightly elevated above the preceding roller will drop below the plane of the upper surface of the preceding roller so that articles being conveyed along the conveyor will continue to move along the conveyor.

The conveyor roller of the present invention is particularly suited for use in friction-type rollers having both inner and outer roller portions. Further, the conveyor roller is both inexpensive to manufacture and can be provided with varied amounts of eccentric movement so as to permit its use in many different conveyor applications.

The various features, advantages and other uses of the present invention should become more apparent by referring to the following detailed description and drawing in which: Figure 1 is an end view of a conveyor having a pair of conveyor rollers of the present invention mounted thereon; Figure 2 is a cross-sectional view generally taken along line 2-2 in Figure 1; and Figure 3 is a side elevational view of the conveyor shown in Figure 1 having a plurality of aligned conveyor rollers constructed in accordance with the teachings of the present invention mounted thereon.

Throughout the following description and drawing, an identical reference number is used to refer to the same component shown in more than one figure of the drawing.

Referring now to Figures 1 and 3, there is illustrated a roller conveyor 10 for transporting articles 1 2 along a predetermined path.

As is conventional, the conveyor 10 includes a pair of spaced side rails 14 and 1 6 which support roller means 1 8 therebetween.

The roller means 1 8 has a substantially circular cross section, with the outer periphery of the roller means 18 defining an articleengaging surface 20 which propels the articles 1 2 along the conveyor 1 0.

The roller means 1 8 may have any suitable configuration, such as a single roller, which extends between and is rotatably mounted at opposed ends to the side rails 14 and 1 6.

Alternatively, the roller means 1 8 may comprise two or more co-axially aligned rollers which are mounted on a drive shaft rotatably supported on the rails 14 and 16.

By way of example and without limitation, the conveyor 10 of the present invention is constructed as a roller conveyor having a plurality of pairs of friction-type rollers 22 and 24, with each roller pair mounted on a rotatable drive shaft. Although only two rollers 22 and 24 are depicted as being mounted on a common drive shaft, it will be understood that any number of rollers may be utilized and disposed at any spacing along the drive shaft.

As shown in Figure 2, each of the rollers, such as the roller 24, has an inner roller portion 26 of circular cross-section and a transversely extending through bore 28. The bore 28 may have any cross-section, such as hexagonal, square, circular, and so forth. An outer roller portion 30 is rotatably mounted about the periphery of the inner roller portion 26 so that the inner surface 32 of the outer roller portion 30 frictionally engages the outer surface 34 of the inner roller portion 26.

Rotation of the inner roller portion 26 causes rotation of the outer roller portion 30 due to the frictionai contact between the mating surfaces 32 and 34. The outer roller portion 30 can also slip with respect to the rotating inner portion 26 when an article 1 2 disposed thereon is stopped for a work operation along the conveyor 10.

A protective coating 38 may optionally be on the periphery of the outer roller portion 30 to form the article-engaging surface 20 of the roller 24. The protective coating 38 may be formed of any suitable wear-resistant material and is typically used to convey articles having a high degree of surface finish.

As shown in Figure 1, a pair of retainers 40 are mounted on the opposite sides of the outer roller portion 30 and engage the outwardly extending surface of the inner roller 26 so as to maintain the outer roller portion 30 in position on the rotating inner roller portion 26. A pair of clamps 42 are mounted on a drive shaft 44 and are secured thereto to maintain the operative components of the roller 24 in position on the drive shaft 44.

It will also be understood that other means for retaining the roller 24, as well as its various components in position on the drive shaft, such as spacer tubes, enlarged retainers or combinations thereof, may also be employed.

The rollers 22 and 24 may be formed of any suitable material, such as a high-strength metal, plastics material and so forth. The inner roller portion 26 can be formed by any process, such as by machining the inner roller portion 26 from a cylindrical piece or by moulding it to the desired size and configuration.

According to the present invention, means are provided for rotatingly and eccentrically mounting the roller on the conveyor 10 so that the outer article-engaging surface 20 of the roller rotates eccentrically during rotation of the roller.

The eccentrically mounting means includes the drive shaft 44 having a cross-section which matches the configuration of the through bore 26 formed in the rollers, such as the roller 24 shown in Figure 2. The drive shaft 44 extends through the aligned bores 26 in the rollers 22 and 24 in each set of rollers and is secured thereto by conventional means. If an hexagonal or square shaped drive shaft 44 is utilized, the flats of the drive shaft mate with the flats of the bore 26 in each of the rollers 22 and 24 to secure the rollers thereon and to rotate the rollers upon rotation of the drive shaft 44. If a circular cross-sectional drive shaft 44 is utilized, the rollers, such as the roller 24, are pinned in the desired position along the length of the drive shaft 44.

Means are provided for rotating the drive shaft 44. As shown in Figure 1, by way of example, the drive means comprises a pair of sprockets 46 mounted on one end of the drive shaft 44. A conventional chain assembly, (not shown), is connected to the sprockets 46 and driven by a motor for rotating the drive shaft 44. Alternatively, a mitre gear assembly, pulleys, and so forth, may also be utilized.

The means for eccentrically mounting each of the rollers 22 and 24 on the drive shaft 44 also includes offsetting the transversely extending bores 28 in each of the rollers 22 and 24 from the transverse centre of each of the rollers 22 and 24. As shown in Figure 2, the transversely extending bore 28 in the inner roller portion 26 of each roller, such as the roller 24, is offset from the transverse centre of the inner roller portion 26 towards one edge of the inner roller 26 to eccentrically offset the roller 26 on the drive shaft 44. The amount of offset can be selected for the particular application of the conveyor 10 and the articles 12 to be conveyed along it. For example, a typical range of eccentricity for each of the rollers is between .020 and .060 inches.

As shown in Figure 2, the eccentricity is achieved by varying the dimensions indicated by dimension lines 50 and 52. The dimension indicated by line 50 is made greater than the corresponding dimension indicated by line 52 so as to locate the transverse bore 28 in the inner roller portion 26 closer to one peripheral edge of the roller than the opposite edge. In this manner, when the inner roller portion 26 is mounted on the drive shaft 44, the outer article engaging surface 20 will move in an eccentric path about the drive shaft 44.

It is preferred that each roller in each set of rollers, such as the rollers 22 and 24, shouid have the same amount of eccentric motion and, more importantly, have the offset portions, such as that indicated by the dimension lines 50 and 52 in Figure 2, disposed in the same angular orientation about the drive shaft 44. In this manner, the outer article-engaging surface 20 of each roller 22 and 24 will move simultaneously in the same eccentric path about the drive shaft 44. However, it is also possible to offset the eccentric portions of each roller 22 and 24 about the common drive shaft 44 to account for different article conveyor engaging surfaces.

In a conventional conveyor 10, as shown in Figure 3, a plurality of roller means are aligned side by side along the length of the conveyor 10. Each set of rollers may include one or more rollers, as shown in Figure 1. As shown in Figure 3, six sets of rollers 60, 62, 64, 66, 68 and 70 are mounted side by side along the conveyor 1 0. By way of example, each of the rollers in each set of rollers has the same amount of offset. Furthermore, each roller in each set of rollers has the offset portions disposed in the same angular position about its drive shaft 44.

Again, it will be noted that adjacent sets of rollers as well as each roller in each set of rollers may have their offset portions disposed in the same or different angular positions about the drive shafts depending upon the configuration of the articles to be conveyed along the conveyor.

For clarity, as shown in Figure 3, the offset portion of the roller 62 is disposed with its greatest offset dimension initially upward from the axis of the drive shaft 44, while the adjacent rollers 60 and 64 have the larger offset dimension disposed in a downwardfacing direction 1804 from that of roller 62.

The rollers 66, 68 and 70 follow the same alternating offset arrangement such that alternating rollers, such as rollers 62, 66 and 70, will have the larger offset dimension initially oriented in an upwardly extending direction, while the remaining rollers 60, 64 and 68 will have the larger offset dimension facing downwards.

Thus, alternating pairs of rollers will engage the bottom surface of the article 1 2 and propel the article 1 2 along the conveyor 1 0.

As the rollers rotate, the smaller offset portions of these rollers will rise above the centre line of the aligned drive shafts 44 but will be spaced from the bottom surface of the part 12, as shown for roller 64. At this time, however, the larger offset portions of rollers 60, 64 and 66 will be above the centre line of the drive shafts 44 to engage and continue to propel the article 1 2 along the conveyor 10.

Although successive rollershave been disposed with like offset portions positioned 180 apart, it will be understood that angular orientations other than 180 may also be employed. Further, the angular position of the offset portions of successive rollers may vary between rollers as well as the amount of offset varying along the length of the conveyor.

Claims (10)

1. A roller conveyor for transporting articles, comprising: a roller having a circular outer article-engaging surface; and means for rotatingly and eccentrically mounting the roller on the conveyor so that the outer article-engaging surface of the roller rotates eccentrically.

2. A roller conveyor as claimed in Claim 1 wherein: the roller includes a transversely extending through bore; a drive shaft rotatably mounted on the conveyor extends through the transversely extending bore in the roller and has the roller secured thereto; and the transversely extending through bore is offset from the transverse centre of the roller so as to cause eccentric movement of the outer article-engaging surface of the roller as the roller rotates.

3. A roller conveyor according to Claim 1 wherein the roller includes: an inner roller portion; an outer roller portion disposed about and frictionally engaging the inner roller portion; and wherein the eccentrically mounting means includes: a drive shaft mounted for rotational movement on the conveyor; a transversely extending through bore formed in the inner roller portion and receiving the drive shaft therethrough; the transversely extending through bore in the inner roller portion being offset from the transverse centre of the inner roller portion so as to cause eccentric motion of the outer article-engaging surface of the outer roller portion as the inner roller portion rotates.

4. A roller conveyor according to Claim 1 and further including: a plurality of co-axially aligned rollers, each having a transversely extending through bore formed therein; and wherein the eccentrically mounting means includes: drive shaft means rotatably mounted on the conveyor and disposed through the bores in the co-axially aligned rollers; the through bores in each of the rollers being offset from the transverse centre of each roller with the offset portions being disposed in the same angular position on the drive shaft means.

5. A roller conveyor as claimed in Claim 4 wherein: the offset portions of each co-axially aligned roller is disposed in the same angular position on the drive shaft means.

6. A roller conveyor as claimed in Claim 4 wherein the drive shaft means includes a drive shaft extending through the transversely extending bores in the co-axially aligned rollers.

7. A roller conveyor for transporting articles comprising: a plurality of aligned roller means, each of circular cross-section with an outer articleengaging surface; means for rotatingly and eccentrically mounting the roller means on the conveyor so that the outer article-engaging surfaces of the roller means rotate eccentrically, the eccentrically mounting means disposing the offset portions of each roller means in a different angular orientation with respect to the offset portions of the adjacent roller means.

8. A roller conveyor as claimed in Claim 7 wherein the eccentrically mounting means comprises: the roller means having a transversely extending through bore formed therein; and drive shaft means rotatably mounted on the conveyor and disposed through the transverse extending bores in the roller means for rotating the roller means.

9. A roller conveyor as claimed in Claim 7 wherein each of the roller means includes a plurality of spaced, co-axially aligned rollers.

10. A roller conveyor including a roller substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.