GB2041111A

GB2041111A - Improvements in rollers

Info

Publication number: GB2041111A
Application number: GB7938890A
Authority: GB
Original assignee: Universal Conveyor Co Ltd
Current assignee: Universal Conveyor Co Ltd
Priority date: 1978-11-11
Filing date: 1979-11-09
Publication date: 1980-09-03

Abstract

The present invention relates to an annular labyrinth seal for a bearing of a roller, the seal having at least one annular lip 38a' projecting axially thereof and at least one annular lip 34a' projecting radially thereof. <IMAGE>

Description

SPECIFICATION Improvements in rollers The present invention relates to rollers, for example idler rollers for supporting conveyors such as troughing conveyors.

Idler rollers generally comprise a hollow cylinder rotatably mounted on a coaxial shaft by suitable bearings such as ball bearings. A major problem associated with the use of such rollers is the protection of the bearings from ingress of dust and dirt and particulary particles of the material being carried by a conveyor running on the rollers. In particularly hazardous environments where, for example the material is sand or crushed rock, the life of an idler roller can be as little as a few months.

In attempting to overcome this problem the bearings have been provided with labyrinth seals but such seals have proved inadequate for protecting the bearings in certain environments.

Accordingly the present invention provides an annular labyrinth seal for a bearing of a roller, the seal having at least one annular lip projecting axially thereof and at least one annular lip projecting radially thereof.

The present invention also provides a roller comprising a cylinderical member mounted for rotation on a coaxial shaft by way of a bearing and an annular labyrinth seal for sealing said bearing at one axial end thereof, the seal having at least one annular lip projecting axially of the roller and at least one annular lip projecting radially of the roller.

The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partial section through one end of an idler roller having a labyrinth seal according to the present invention; and Figure 2 is a partial section through one end of an idler roller having a further form of labyrinth seal according to the present invention.

Referring to Fig. 1, the idler roller 10 comprises a hollow cylindrical member 1 2 mounted at each end for rotation of a coaxial shaft 1 4 by way of ball bearings 1 6 (only one of which is shown). The construction of the roller is normally the same at each axial end and so for convenience only the right hand end is shown in the drawing and described in detail.

The inner race 18 of the ball bearing 1 6 is preferably sealingly mounted on the shaft 1 4 by two O-rings 20 while its outer race 22 is a press fit in an annular recess 24 formed in an annular end cap 26 which, together with the bearing 1 6 closes the end of the cylinder 12.

The end cap 26 is itself a press fit in an annular groove 28 in the inner surface of the cylinder 1 2 and is retained by a peened-over edge 30 of the cylinder 1 2.

The bearing 1 6 is sealed tothe outside by a labyrinth seal 32 which, in the preferred embodiment comprises three annular portions 34, 36 and 38. The portion 34 is secured to the shaft 14, conveniently as a press fit, and has a radially outwardly extending lip 34a.

The portion 36 is secured, again conveniently as a press fit, in an annular groove in the end cap 26 and has a radially inwardly extending lip 36a which overlaps the lip 34a.

Although the lip 36a is shown axially to the right of lip 34atheir axial positions can of course be reversed. The third and major portion 38 of the seal is substantially U-shaped in cross-section, the radially inner limb of the "U" abutting the shaft 14 and again this is conveniently a press fit. The radially outer limb which forms the lip of the portion is somewhat longer than the inner limb and is substantially wedge-shaped in cross-section. It extends axially of the roller into a correspondingly shaped annular recess in the end cap 26 with a clearance conveniently in the range 0.5 to 0.75mm.

As can be seen from the drawings the three lips 34a, 36a and 38a provide a tortuous path which traps specks of dirt, etc., before they reach the bearings. The seal can of course be made more complex by the provision of multiple lips 34a, 36aand 38a. The lips 34a and 36a may even carry further axially extending lips which cooperate with one another to extend the tortuous path.

The bearing 1 6 is also sealed from the interior of the roller by a seal 40 which is a press fit on the shaft 1 4. This seal is not an elaborate seal since the interior of the roller is a relatively clean environment.

Any slack or movement between the seal 40, bearing 1 6 and portions 34 and 38 is taken up by two annular disc springs 42 located on the shaft, one at each axial side of the bearing and seals assembly. The axial locations of the springs 42 on the shaft 1 4 are set by respective circlips 44 and the radially outer rims of the springs 42 act respectively on the seal 40 and portion 38 to force the seal 40 and portions 34, 38 towards the bearing 16.

Fig. 2 shows a modified form of labyrinth seal to that of Fig. 1. The annular end cap 26' of this seal serves a similar purpose to the cap 26 of Fig. 1 in mounting the outer race 22 of the bearing 1 6 but also serves as 3 portion of the labyrinth seal, having a radix" inwardly projecting annular flange 50 which replaces the portion 36 of the seal of Fig. 1.

A further portion 38' of the seal of Fig. 2 has an axially inwardly extending lip 38a' in a similar manner to the portion 38 of the Fig. 1 seal but the radially inner limb of the portion 38' also seats the inner race 1 8 of the bearing 1 6 and the third portion 34' of the seal.

The portion 34' is conveniently T-shaped as opposed to the L-shape of portion 34 to provide better seating on the portion 38'. The springs 42 and circlips 44 of Fig. 1 may also be provided in the embodiment of Fig. 2, on either or both sides of the seal. A further seal 40 may conveniently be added to seal the bearing 16 from the interior of the roller.

The labyrinth seals described above may be made of any suitable material such as zinc alloy or plastics material, and are conveniently packed with grease in use.

Claims

1. An annular labyrinth seal for a bearing of a roller, the seal having at least one annular lip projecting axially thereof and at least one annular lip projecting radially thereof.

2. A seal as claimed in claim 1 comprising at least two portions and wherein a radial lip of one portion and an axial lip of the other portion cooperate to form a labyrinth.

3. A seal as claimed in claim 2 wherein at least one of said lips of one of said portion projects into a corresponding groove in the other portion.

4. A seal as claimed in claim 1, 2 or 3 comprising three portions wherein two of said portions combine to form at least one annular recess into which a lip of the third portion engages.

5. A seal as claimed in claim 4 wherein an annular lip of one of said two portions projects into an annular groove of the third portion.

6. A seal substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

7. A seal substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

8. A roller comprising a cylindrical member mounted for rotation on a coaxial shaft by way of a bearing and an annular labyrinth seal for sealing said bearing at one axial end thereof, the seal having at least one annular lip projecting axially of the roller and at least one annular lip projecting radially of the roller.

9. A roller as claimed in claim 8 having an annular labyrinth seal as claimed in any of claims 1 to 7.