GB2050531A

GB2050531A - Conveyor roller

Info

Publication number: GB2050531A
Application number: GB7908393A
Authority: GB
Original assignee: SKF UK Ltd
Current assignee: SKF UK Ltd
Priority date: 1979-03-09
Filing date: 1979-03-09
Publication date: 1981-01-07
Also published as: ES8104515A1; CA1134890A; FR2450763B3; ES489300A0; ZA801356B; IT8020424A0; GB2050531B; ZA801265B; IT1129729B; AU535621B2; US4315566A; AU5627780A; FR2450763A3; DE8005696U1

Description

1

SPECIFICATION End Cap Assemblies for Conveyor Rollers

This invention relates to conveyor rollers of the kind comprising a roller tube fitted with end cap assemblies incorporating bearings for rotatably mounting the roller tube on a fixed shaft.

End cap assemblies having housings made of sheet metal are commonly secured in conveyor roller tubes by swaging the tube onto each end cap assembly, the end cap housing being deformed at the same time as the tube is reduced in diameter by the swaging operation. It is known to swage steel roller tubes onto end cap assemblies having housings made of plastics material, but hitherto the plastics housings have generally been rigid in form and moulded to the final shape which will be taken up by the deformed steel tube. It is difficult to obtain an acceptable rotational secure fit by swaging a tube down on to such a pre-formed, rigid, moulded plastics housing, since the steel tube when deformed is subject to a degree of "spririg-back" which reduces or can even remove the force acting between the housing and the steel tube.

The object of the invention is to provide an improved construction of end cap assembly having a housing of plastics material which can be secured radially in a roller tube by swaging the tube.

According to the invention there is provided an end cap assembly for a roller tube of a conveyor roller, comprising a housing of plastics material and a bearing mounted in the housing, wherein one portion of the housing forms a substantially rigid annular frame which supports the bearing therein, and another portion of the housing forms a spring support which surrounds the frame and is of a size to be a sliding fit within an end of the roller tube, one end of the support being integral with the frame and the other end of the support being spaced from the frame and movable radially inwards against its own resilient resistance to deformation, whereby, upon mounting the end cap assembly in an end of a roller tube with said one end of the support axially innermost, the end of the roller tube may be swaged radially inwards to secure the end cap assembly firmly in the roller tube.

The end cap assembly of the invention has the advantage that, when the end of a roller tube is swaged onto the end cap assembly with the spring support forced radially inwards, the spring support tends to return to its original position and thereby maintains a force between the frame of the housing and the tube bore should "spring- back" occur in the tube after the swaging tool has been removed, thus ensuring that the end cap assembly will be firmly secured radially in the tube.

The spring support can conveniently comprise 125 a cylindrical sleeve supported at one end thereof on an external wall of the frame of the end cap housing by a bight portion of U-shaped cross section integral with the sleeve and the external GB 2 050 531 A L_ wall. The sleeve may be slit longitudinally to increase its flexibility. Alternatively, the spring support may comprise spring fingers spaced around the frame or a spring lattice framework positioned around the rigid frame of the housing.

The spring support is preferably provided at its - free end with a flange adapted to abut the end of the roller tube when the end cap assembly is being mounted in the tube, so as to locate the end cap assembly axially within the tub. After the swaging operation, the reduced diameter on the tube prevents outward axial movement of the end cap assembly and the flange on the spring support prevents axial inward movement of the end cap assembly.

The provision of the flange on the spring support provides a further advantage over the known construction described above in which a roller tube is swaged onto a preformed rigid housing of plastics material moulded to the final shape of the tube. In such constructions it is not possible to provide a flange abutting the end of the tube during initial assembly since the tube diameter will necessarily be too large to engage the flange before the swaging operation, and other means must be provided to locate the end cap assembly axially.

The end cap assembly of the present invention, provided with a flange on the spring support, can thus be simply located in a tube, both axially and radially, merely by swaging the tube to reduce its diameter.

In a preferred construction of the end cap assembly of the invention, the spring support is spaced close to the annular frame of the housing so that it abuts against the frame under the swaging pressure applied to the end of the roller, and the external surface of the annular frame is curved radially inwards in a direction away from the fixed end of the spring support, whereby the spring support is deflected to the curvature of the external surface of the frame, so as to limit the strain in the spring support to a predetermined value, when the end of the roller tube is swaged radially inwards to force the spring support into engagement with the frame. In addition, the annular frame is provided with radial webs spaced around the frame and adapted to transmit the loads acting on the conveyor roller tube to the bearings and spread these loads axially across the housing.

An embodiment of the invention will now be described, by way of example with reference to the accompanying drawings, in which:

Figure 1 is an end view of an end cap assembly for a conveyor roller, taken in the direction of arrow A in Figure 2, Figure 2 is a cross sectional side elevation of the end cap assembly of Figure 1, Figure 3 is an end view of the end cap assembly taken in the direction of arrow B in Figure 2, and Figure 4 is a cross sectional side elevation of one end of a conveyor roller incorporating the end cap assembly of Figures 1-3 1 i i 1 i 1 2 The end cap assembly shown in the drawings comprises a housing 10 fitted with a ball bearing 11, an end cover 12 engaged as a snap fit in the bore of the bearing, and an annular felt seal 13 compressed between the housing and the end cover.

The housing 10 is made of a resilient plastics material, preferably glassfibre reinforced nylon, and comprises a cylindrical inner wall 15, a cylindrical outer wall 16 surrounding the inner wall 15, an end wall 17 integral with adjacent ends of the walls 15, 16, and a plurality of radial webs 18 (Figure 3) spaced around the housing and extending between the inner and outer walls 15, 16, the webs 18 being integral with the walls 15, 16, 17. A cylindrical sleeve 19 surrounds the wall 16 and is connected thereto at the end remote from end wall 17 by an annular bight portion 20 of U-shaped cross section, to form a spring support for the end cap assembly. The end of the sleeve 19 remote from the bight portion 20 is formed with a radial flange 2 1. The end of the cylindrical inner wall 15 remote from wall 17 is formed with an annular step 22 forming an abutment for the bearing 11, and a further end wall 23 integral with the step 22 extends radially inwards as shown in Figure 2. The inner periphery of the end wall 23 is formed with an axially extending annular flange 23' which terminates close to the inner ring of the bearing.

The outside surface of the outer wall 16 of the housing is formed with a plurality of axially extending ribs 24 spaced around the housing, each rib being radially aligned with one of the radial webs 18. The ends of the ribs 24 adjacent the bight portion 20 have radially outer surfaces which are flat and parallel and spaced close to the inside surface of the sleeve 19, and the remainder of the radially outer surfaces 25 of the ribs are curved radially inwards in the axial direction away from the bight portion 20. The end wall 17 is formed with two concentric annular tongues 2, 6, 27 on the side remote from the webs 18, the radially outer tongue 26 having a curved outer surface which forms an extension of the curved outer surfaces 25 of the ribs 24.

The ball bearing 11 comprises an outer bearing ring 30, an inner bearing ring 31 and balls 32 in rolling engagement with grooved tracks on the rings 30, 31 so that the bearing is capable of resisting radial forces and axial forces in both directions. The outer ring 30 is a tight fit against the inside surface of the cylindrical wall 15 and abuts against the step 22.

The end cover 12 is also made of resilient plastics material, preferably unfilled nylon, and comprises an annular disc 35 formed on one side with three concentric annular tongues 36, 37, 38 and a cylindrical flange 39 at the centre of the disc 35. The free end of flange 39 is split axially and formed into four resilient fingers 40 having enlarged ends 41 which extend through the bore of the inner bearing ring 31 and engage as a snap fit on the chamber thereof, and the centre portion of the flange 39 is formed with an annular step 42 GB 2 050 531 A 2_ which abuts against the adjacent face of the inner bearing ring when the enlarged ends of the fingers engage the opposite side of the inner bearing ring, thereby axially locating the end cover relative to the bearing and the housing 10. The radially outer tongue 36 on the cover projects between the tongues 26, 27 on the housing, and the tongue 37 on the cover is spaced close to the tongue 27 on the housing, so as to provide a narrow tortuous gap between the tongues 37, 27, 36, 26 forming a labyrinth sea[ between the housing and the cover.

The annular felt sea[ 13 is mounted as a close fit in the annular recess formed between the tongues 37, 38 on the cover, and has an axial width such that it is compressed between the cover and the housing so as to be in rubbing contact with the end wall 17 of the housing upon rotation of the housing relative to the cover. The seal 13 thus closes off the radially inner end of the narrow gap of the labyrinth seal. The annular recess 45 between the tongue 38 and the cylindrical flange 39 on the cover is filled with grease for lubricating the bearing, the seal 13 preventing escape of the grease through the labyrinth.

The end cap assembly is designed for use with a cylindrical steel roller tube having an internal diameter such that the sleeve 19 of the end cap assembly is a hand push-fit within the roller tube, the roller tube having an external diameter which is not smaller than that of the flange 21. The end cap assembly is secured in position in the end of the roller tube, with the flange 21 abutting the end of the tube, by swaging the end of the roller tube radially inwards, that is reducing the diameter of the end of the roller tube by external pressure,so as to force the sleeve 19 against the ribs 24 on the housing as shown in Figure 4. The 1 OEj walls 15, 16, 17 and the radial webs 18 form a substantially rigid frame which resists deformation under the swaging pressure applied to the roller tube. The swaging operation is preferably controlled by a pressure transducer designed to prevent the swaging pressure exceeding a predetermined maximum value.

In the swaging operation the end of the roller tube must of course be deformed beyond its elastic limited so as to prevent or reduce "springback" of the roller tube. The housing of the end cap assembly is however made of plastics material having a higher degree of elasticity than the metal of the roller tube. The length of the sleeve 19 and the radius of curvature of the outer surfaces 25 of the ribs 24 and tongue 26 are such that, when the sleeve 19 is forced onto the ribs 24 and the tongue 26, the strain in the sleeve 19 does not exceed a predetermined value at any point along its length. Thus, after the swaging operation, the sleeve 19 acts as a spring which provides and maintains a force between the housing and the bore of the roller tube should spring back" occur in the tube after the swaging tool has been removed, thereby ensuring that the end cap assembly is a firm non-rotational fit 3 GB 2 050 531 A 3_ within the roller tube. The end cap assembly is of course secured against outward axial movement by the swaged end of the roller tube, and against inward axial movement by engagement of the flange 21 against the end of the roller tube. The external diameter of the end of the roller tube is not less than that of the flange 2 1, as explained above, to ensure that the swaging tool contacts the steel tube and not the flange 21 during the swaging operation.

The strain in the housing material is preferably the maximum under which significant creep or relaxation of the plastics sufficient to loosen the fit of the end cap in the roller tube will not occur in service.

The end cap assembly, fitted in the roller tube, is mounted on a shaft 46 (Figure 4) fixed in the frame of a conveyor, the shaft 46 being a close sliding fit in the bore of the cylindrical flange 39 on the cover. The end cap assembly is axially located by a circlip 47 engaged in a groove in the shaft as shown in Figure 4.

Claims

Claims

I. An end cap assembly for a roller tube of a conveyor roller, comprising a housing of plastics material and a bearing mounted in the housing, wherein one portion of the housing forms a substantially rigid annular frame which supports the bearing therein, and another portion of the housing forms a spring support which surrounds the frame and is of a size to be a sliding fit within an end of the roller tube, one end of the support being integral with the frame and the other end of the support being spaced from the frame and movable radially inwards against its own resilient resistance to deformation, whereby, upon mounting the end cap assembly in an end of a roller tube with said one end of the support axially innermost, the end of the roller tube may be swaged radially inwards to secure the end cap assembly firmly in the roller tube.
2. An end cap assembly as claimed in claim 1, wherein said other end of the spring support is formed with a flange to abut against the end of the roller tube and thereby axially locate the end cap assembly therein when the assembly is fitted in the end of the roller tube.
3. An end cap assembly as claimed in claim 1 or 2, wherein the spring support comprises a cylindrical sleeve supported at one end thereof on an external wall of the frame by a bight portion of U-shaped cross section integral with the sleeve and said external wall.
4. An end cap assembly as claimed in any of claims 1-3, wherein the spring support is movable radially inwards into abutting contact with the annular frame under swaging pressure applied to the end of the roller tube.
5. A conveyor roller comprising a roller tube fitted at each end thereof with an end cap assembly as claimed in any of claims 1-4, the said one end of the spring support of each end cap assembly being axially innermost, and the ends of the roller tube being swaged radially inwards.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981. Published by the Patent Office, 25 Southampton Buildings, London, WC2A l AY, from which copies maybe obtained.

5. An end cap assembly as claimed in claim 4 wherein the external surface of the annular frame is curved radially inwards in a direction away from 125 said one end of the spring support, whereby the spring support is deflected to the curvature of the external surface of the frame, so as to limit the strain in the spring support to a predetermined value, when the end of the roller tube is swaged radially inwards to force the spring support into engagement with the frame.

6. An end cap assembly as claimed in claim 4, wherein the outer surface of the annular frame is formed with a plurality of axially extending ribs which taper radially inwards in a direction away from said one end of the spring support.

7. An end cap assembly as claimed in claim 6, wherein the outer surfaces of at least the end portions of said ribs remote from said one end of the spring support are curved radially inwards in a direction away from said one end of the spring support.

8. An end cap assembly as claimed in any of the preceding claims, wherein the annular frame comprises an axially-extending inner wall, an axially-extending outer wall surrounding the inner wall, and a plurality of radial webs spaced around the frame and extending between the inner and outer walls, the bearing unit being mounted as a force fit in the bore defined by the inner wall, and the radial webs being adapted to spread any load acting on the end cap assembly axially across the go frame.

9. An end cap assembly as claimed in claims 7 and 8, wherein each of said ribs is aligned radially with a separate one of said radial webs.

10. A conveyor roller comprising a roller tube fitted at each end thereof with an end cap assembly as claimed in any of claims 1-9, the said one end of the spring support of each end cap assembly being axially innermost, and the ends of the roller tube being swaged radially loo inwards.

11. A conveyor roller as claimed in claim 10, wherein the spring support in each end cap assembly engages against the internal wall of the tube substantially along the full length of the spring support.

12. A conveyor roller as claimed in claim 10 or 11, and fitted with a shaft mounted in the bearings of the end cap assemblies.

13. A conveyor roller as claimed in any of claims 10-12, in which the spring support of each end cap assembly is formed with a flange which abuts against the associated end of the roller tube, wherein, prior to the swaging operation, the spring support of each end cap assembly is a close sliding fit in the bore of the roller tube and the external diameter of the flange on the support is not greater than the external diameter of the roller tube.

14. A method of making a conveyor roller from a roller tube and two end cap assemblies as claimed in any of clams 1-9 and adapted to be a hand push fit within the ends of the roller tube, comprising fitting in each end of the tube an end cap assembly with said one end of the spring support axially innermost, and swaging the end of the roller tube to engage the support against the outside surface of the annular frame of the end cap assembly.

1 1 4 GB 2 050 531 A 4 New Claims or Amendments to Claims filed on 5.3.80. Superseded Claims: 1- 14.

New or Amended Claims:

1. An end cap assembly for a roller tube of a conveyor roller, comprising a housing of plastics 35 material and a bearing in said housing for rotatably mounting the assembly on a shaft, one portion of the housing forming a substantially rigid annular frame which supports the bearing therein, and another portion of the housing forming a spring support which surrounds the frame and is of a size to be a sliding fit within an end of the roller tube, one end of the support being integral with the frame, and the other end of the support being spaced from the frame and 45 movable radially inwards against its own resilient resistance to deformation into abutting contact with the annular frame, wherein the external surface of the annular frame is curved radially inwards in a direction away from said one end of 50 the spring support, whereby, upon mounting the end cap assembly in an end of a roller tube with said one end of the support axially innermost, the end of the roller tube may be swaged radially inwards to force the spring support into engagement with the frame with at least part of the spring support lying along the curved external surface of the frame, so as to secure the end cap assembly firmly in the roller tube.

2. An end cap assembly as claimed in claim 1 wherein the external surface of the annular frame is formed with a plurality of axially extending ribs, at least the end portions of said ribs remote from said one end of the spring support being curved radially inwards in a direction away from said one end of the spring support.

3. An end cap assembly as claimed in claim 2, wherein the annular frame comprises an axially- extending inner wall, an axially-extending outer wall surrounding the inner wall, and a plurality of radial webs spaced around the frame and extending between the inner and outer walls, the bearing unit being mounted as a force fit in the bore defined by the inner wall, and the radial webs being adapted to spread any load acting on the end cap assembly across the frame.

4. An end cap assembly as claimed in claim 3, wherein each of said ribs is aligned radially with a separate one of said radial webs.