GB2386400A

GB2386400A - Recessed-flanged bearing

Info

Publication number: GB2386400A
Application number: GB0206294A
Authority: GB
Inventors: Gordon Burke; Iain Mcintosh; Grant William Smith
Original assignee: NCR International Inc
Current assignee: NCR International Inc
Priority date: 2002-03-15
Filing date: 2002-03-15
Publication date: 2003-09-17
Also published as: GB0206294D0

Abstract

A flanged bearing (10,110) for inserting into an aperture (42) in sheet metal (40) is described. The bearing (10,110) comprises a sleeve (12,112) and a flange portion (14,114) at one end (16,116) of the sleeve (12,112). The flange portion (14,114) defines a recess (22,122) for accommodating debris (48) removed from the sleeve (12,112) on insertion into the sheet metal aperture (42). The sleeve (112) may define a compensation gap (128) for facilitating expansion and contraction of the sleeve (112), and the flange portion (114) may include one or more anti-rotation keys (130) for inter-engagement with one or more grooves defined in the sheet metal in the vicinity of the aperture for preventing the flange from rotating.

Description

FLANGED BEARING

The present invention relates to a flanged bearing.

In particular, the invention relates to a polymer flanged bearing, such as a polymer flanged plain bearing.

Polymer flanged bearings are commonly used because 5 they can be produced from a wide range of materials (for example: nylon, polytetrafluoroethylene, polycarbonate, acetal, polyimide, and such like), and can have advantageous characteristics (such as self-lubrication, wear resistance, and low static properties).

0 Furthermore, bearings made from polymer material are typically less expensive to manufacture than bearings made from other types of material (such as sintered bronze).

Polymer bearings may also be more resistant to environmental factors, such as extremes of temperature, IS moisture, chemicals, and such like, than other types of material. Polymer flanged plain bearings typically comprise a cylindrical sleeve having a flange portion at one end.

One disadvantage of flanged plain bearings made 20 exclusively of polymer material is that they have limited use in some sheet metal applications. In some sheet metal applications, an aperture is punched in sheet metal, and a flanged bearing is inserted into the punched aperture so that an interference fit is formed between the sheet metal 25 defining the punched aperture and the sleeve of the inserted bearing.

To achieve a successful interference fit between two parts, the part being inserted must have a larger outer dimension than the part into which it is inserted.

30 Insertion of the part under pressure causes the part to deform locally creating a tight fit condition. The

À -2 strength of the fit is determined by the amount of interference between the parts and by the materials used, in particular, the elasticity and deformation characteristics of the materials. If a material is 5 required that has low elasticity, then some removal of the material during insertion may be unavoidable, even if the dimensions of the parts are selected to produce an interference condition that minimizes the material removal. lo When an aperture is punched, a lead-in (a gently sloping portion sometimes referred to as the penetration depth) is produced on the sheet metal side nearest the aperture punch, and a break-away (a series of jagged edges sometimes referred to as the burr height) is produced on the sheet metal side furthest away from the aperture punch. The side walls of the aperture include a smooth surface (referred to as the burnish depth) near the lead in, and a rough surface (referred to as the fracture depth) extending from the burnish depth to the break-away.

JO If a bearing is inserted through the lead-in side then typically the bearing will be guided by the lead-in and will align correctly. When the bearing is being inserted, the rough surface on the sides of the aperture typically remove some polymer material from an outer 5 surface of the bearing sleeve. Although, this material acts as debris, it does not usually affect the alignment of the bearing because it is usually trapped in the space between the flange and the lead-in.

If the bearing is inserted through the break-away 30 side, however, then polymer material removed by the jagged edges and/or the rough surface becomes trapped between an outer surface of the sheet metal and the flange portion.

This removed material acts as debris and hinders the bearing from being mounted flush with the sheet metal, thereby increasing the possibility of non-parallel insertion of the bearing, which leads to misalignment of 5 any shaft inserted into the bearing.

To reduce tooling and manufacturing costs for a framework having a right side that is a mirror image of a left side, it is conventional to use common frames for the right and left sides. However, this results in one frame lo defining apertures where the lead-in is on an outer surface; whereas, the other frame defines apertures where the break-away is on an outer surface. Thus, at least one frame requires a secondary operation to remove the break-

away from each aperture so that an inserted bearing can be 15 mounted flush with the sheet metal.

This secondary operation results in additional processing and handling time, and increased costs. These increased costs may offset the reduced cost of using polymer bearings.

20 It is among the objects of an embodiment of the present invention to obviate or mitigate one or more of the above disadvantages, or other disadvantages associated with flanged polymer bearings.

According to a first aspect of the present invention there is provided a flanged bearing for inserting into an aperture in sheet metal, the bearing comprising a sleeve and a flange portion at one end of the sleeve, characterized in that the flange portion defines a recess for accommodating debris removed from the sleeve on 30 insertion into the sheet metal aperture.

Preferably, the recess is an annular recess.

Preferably, the recess defined by the flange portion is a substantial proportion of the width of the flange, for example, twenty and sixty percent of the thickness of the flange. In one embodiment, the recess forms 5 approximately forty-four percent of the width of the flange. Preferably, the sleeve includes a tapered portion at an opposite end to the flange portion for reducing interference between the sleeve and sheet metal defining lo the aperture. Alternatively or additionally, the sleeve may define a compensation gap for facilitating expansion and contraction of the sleeve.

The flange portion may include one or more anti-

rotation keys for inter-engagement with one or more grooves defined in the sheet metal in the vicinity of the aperture for preventing the flange from rotating.

The bearing is preferably a plain bearing, but may be a flanged ball bearing, a flanged roller bearing, a flanged thrust bearing, or any other convenient type of 20 flanged bearing.

By virtue of this aspect of the invention, a flanged polymer bearing is provided that can be inserted into punched sheet metal from either side of the punched aperture. If the flanged polymer bearing is inserted from 25 the break-away side of the sheet metal, then any debris removed by the break-away side will be accommodated by the recess, thereby allowing the flange portion to be placed flush with the sheet metal. This obviates the requirement for expensive and time-consuming secondary operations.

30 It is counter-intuitive to provide a recess that may partly accommodate the series of jagged edges, as these

edges can be used to penetrate the flange portion and reduce the possibility of the bearing rotating.

These and other aspects of the present invention will be apparent from the following specific description, given

5 by way of example, with reference to the accompanying drawings, in which: Fig 1A is an end view of a polymer flanged bearing according to one embodiment of the present invention; Fig 1B is a sectional side view of the bearing of lo Fig 1A; Fig 2 is a sectional side view of the bearing of Figs 1A and 1B during insertion into a sheet metal aperture; Fig 3 is a sectional side view of the bearing of is Figs 1 A and 1B after the bearing has been inserted into a sheet metal aperture; and Fig 4 is a side view of a bearing according to an alternative embodiment of the present invention.

Reference is now made to Figs 1A and 1B, which 20 illustrate a polymer flanged bearing 10 made of extruded acetal. The bearing 10 comprises a cylindrical sleeve 12 having a flange portion 14 at a rear end 16 and a tapered portion 18 (referred to as a lead-in) at a front end 20.

The bearing 10 is approximately 6mm long, and the flange 2 portion 14 has an outside diameter of approximately 13mm.

The flange portion 14 defines a circular annular recess 22 at the flange portion surface nearest the rear end 20. The circular annular recess 22 has an internal diameter of approximately 9mm and an external diameter of 30 approximately 12mm. The sleeve 12 includes an interference portion 24 between the tapered portion 18 and the flange portion 14. The tapered portion 18 is tapered

-6- at an angle 26 of approximately fifteen degrees. The interference portion 18 has a length of approximately 3mm.

Reference is now made to Figs 2 and 3, which show the bearing 10 being inserted into sheet metal 40, and in situ s in sheet metal 40, respectively. The sheet metal 40 is approximately 3mm thick, and defines a punched aperture 42 having a lead-in 44 and a break-away 46.

The bearing 10 is inserted into the aperture 42 with a force of approximately 150 Newtons, and the sheet metal lo 40 defining the aperture removes some of the bearing material during insertion, producing debris 48.

When the bearing 10 has been fully inserted, the debris 48 is located in the recess 22, thereby allowing the flange portion 14 to mount flush with the sheet metal 40, as shown in Fig 3.

It will now be appreciated that the above embodiment has the advantage that a flanged polymer bearing can be inserted into sheet metal from either side of a punched hole. The inclusion of a tapered lead-in on the outer So surface reduces the interference between the bearing and the sheet metal. This reduces the contact between the outer surface of the sleeve and the sides of the hole, thereby reducing the amount of material removed from the sleeve during insertion. In the above embodiment, the 25 length of the interference portion is approximately equal to the thickness of the sheet metal, thereby minimising the amount of material removed from the sleeve.

An annular undercut on the inside of the flange creates an improved fit by producing space into which 30 shaved material from the bearing can collect, allowing the bearing to be inserted flush against the flange.

Reference is now made to Fig 4, which illustrates an alternative embodiment of the present invention. Fig 4 shows a bearing 110 made of extruded polycarbonate and as comprising a cylindrical sleeve 112 having a flange

portion 114 at a rear end 116 and a tapered portion 118 (referred to as a lead-in) at a front end 120. The flange portion 114 defines an annular recess 122 at the flange portion surface nearest the rear end 120. The sleeve 112 5 includes an interference portion 124 between the tapered portion 118 and the flange portion 114. The tapered portion is tapered at an angle 126 of approximately twenty degrees. The interference portion 118 has a length approximately equal to the thickness of the sheet metal lo into which the bearing 110 is to be inserted. The sleeve 112 also defines a compensation gap 128 extending along the sleeve 112. The flange portion 114 includes an anti-

rotation key 130 to engage with a groove defined by sheet metal in the vicinity of the aperture.

15 In use, the bearing 110 is inserted into a sheet metal aperture in a similar manner to bearing 10.

However, the compensation gap 128 may reduce the amount of material removed from the sleeve 112 because the gap can be compressed on insertion into the aperture.

20 Various modifications may be made to the above described embodiments within the scope of the invention, for example, in other embodiments, the flange portion may be a flange that is constructed independently of the sleeve and bonded to the sleeve by a fastening technique 25 (for example, using ultrasonic welding) to produce the bearing. In other embodiments, the bearing may be moulded in a plurality of interlocking pieces, such as a male/female configuration. In other embodiment, a different polymer may be used. In other embodiments, the So dimensions and taper angle may be different to those given above. In other embodiments, no tapered portion may be required. In other embodiments, a different type of flanged bearing may be provided, for example, a ball race flanged bearing.

Claims

-8 Claims

1. A flanged bearing (10,110) for inserting into an aperture (42) in sheet metal (40), the bearing (10,110) comprising a sleeve (12,112) and a flange portion (14,114) 5 at one end (16,116) of the sleeve (12,112), characterized in that the flange portion (14,114) defines a recess (22, 122) for accommodating debris (48) removed from the sleeve (12,112) on insertion into the sheet metal aperture (42). lo

2. A bearing according to claim 1, wherein the recess (22,122) is an annular recess.

3. A bearing according to claim 1 or 2, wherein the recess defined by the flange portion is a substantial proportion of the width of the flange.

15

4. A bearing according to any of claims 1 to 3, wherein the sleeve (12, 112) includes a tapered portion (18,118) at an opposite end (20,120) to the flange portion (14,114) for reducing interference between the sleeve (12,112) and sheet metal (40) defining the aperture (42).

20

5. A bearing according to any preceding claim, wherein the sleeve (112) defines a compensation gap (128) for facilitating expansion and contraction of the sleeve (112).

6. A bearing according to any preceding claim, 25 wherein the flange portion (114) includes one or more anti-rotation keys (130) for interengagement with one or more grooves defined in the sheet metal in the vicinity of the aperture for preventing the flange from rotating.

7. A bearing according to any preceding claim, wherein the bearing is a plain bearing.