GB2129065A

GB2129065A - Fluid bearing idler roller

Info

Publication number: GB2129065A
Application number: GB08230696A
Authority: GB
Inventors: John Hanham Page
Original assignee: Kodak Ltd
Current assignee: Kodak Ltd
Priority date: 1982-10-27
Filing date: 1982-10-27
Publication date: 1984-05-10
Also published as: GB2129065B

Abstract

An idler roller arranged to be driven by contact with a moving web supported thereby comprises a non-rotatable cylindrical fluid permeable support (13) and a expansible sleeve closely fitting thereover. The sleeve is impermeable to fluid. Means (17) are provided for feeding fluid under pressure to the support (13). The fluid, pressure, passes through the support (13) and forms a fluid filled annulus between the support (13) and the sleeve (18) whereby the sleeve (18) is free to rotate on the annulus of fluid. The fluid used is preferably air whereby the sleeve (18) is rotatable in a substantially frictionless manner on the annulus of air. <IMAGE>

Description

SPECIFICATION Idler roller This invention concerns idler rollers i.e. rollers which support and are driven by the passage thereover or therearound or an article such as a continuous web. As the article drives the roller, there must be friction therebetween and a force must be imparted to the roller to overcome any friction in the bearings of the roller.

It is known to use "air bearings" as idler rollers.

A perforate member is supplied with air or other fluid under pressure which fluid issues from the perforations and forms a cushion on which the article is supported as it passes thereover or therearound. Control of a web of material passing partly around such an air bearing is difficult and, if it is desired to steer a web with such roller, further difficulties are encountered.

It is an object of the present invention to provide an idler roller which permits the same physical control of an article such as a web passing thereover or therearound, as a friction driven idler roller but presents to the article such as a web, the substantially frictionless low inertia support provided by an air bearing.

According to the present invention, there is provided an idler roller comprising a cylindrical support member, having an inlet at one end for fluid under pressure, a passage therein permitting fluid to be fed to and through holes in the cylindrical surface thereof, and a substantially fluid impermeable sleeve forming a tight fit over at least part of the cylindrical surface of the support member such that when fluid is introduced to the support member, the sleeve is expanded thereby so as to be freely rotatable on the support member substantially without friction.

Adjustable end flanges may be provided on the support member and arranged adjacent the ends of the sleeve to reduce the escape of fluid therefrom.

The support member may comprise a porous tube of a material such as sintered bronze.

Alternatively, it may comprise a stainless steel perforated sheet, wrapped about an appropriately dimensioned former and butt welded or overlap welded to form a tubular support member.

The sleeve may be a flexible film of metal plastics material or some other form of non porous substantially impermeable material extensible under the action of fluid pressure to provide a clearance fit on the support member.

The support member may be provided with one or more tappings preferably along the centre line of the arc of contact, whereby the fluid pressure may be measured at the or each tapping. The fluid pressure measurements are indicative of the tension in a web supported by the idler roller.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic representation of part of a web transport path wherein idler rollers according to the invention may be employed, and Fig. 2 is an axial section of an idler roller according to the present invention..

Referring firstly to Fig. 1, a continuous web 10 of material such as paper, is transported through an apparatus which may, for example, be- a drying chamber. Transport is effected by winding the web 10 on a take up reel (not shown). The web 10 passes over a. first idler roller 1 1- having a wrap of about 1 59 for support, and over a second idler roller 12 having a wrap of approximately 1800 therearound. It is to be understood that the transport path is chosen merely to exemplify the use of idler rollers according to the invention.

Referring. now to Fig. 2, each of the idler rollers 11 and 12 comprise a cylindrical support member 1 3 formed of a porous material such as sintered bronze and of rigidity and strength sufficient to provide the required support for the web 1 0. The support member has end plates 14, 1 5 wherethrough an axial shaft 1 6 extends. The support member 13 may thus be supported by one end (as shown) or by extending the shaft 16, by both ends. An air supply hose 1 7 provides air under pressure to the interior of the support member 13.

A substantially impermeable sleeve 1 8 of a material such as plastic or metal foil is a tight fit over the support member 13 and is of axial length at least equal to the width of the web 10 to be supported thereby. Flanges 19, 20 are mounted on the support member closely adjacent each end of the sleeve 18.

End plugs 21, 22 extend interiorily of the support member 13 to seal the interior surfaces thereof between the end plates 14, 1 5 and the respective flanges 19, 20.

The material or which the sleeve 1 8 is formed is chosen such as to be slightly extensible so that, upon the introduction of air under pressure through the hose 1 7 to the interior of the support member, the sleeve is radially expanded to provide a clearance between itself and the support member 13 forming a controllable air bearing. The pressure of the air, upon stabilisation is a function of the tension in the web 10. Such tension can be measured by providing a plurality of tappings 23 in the support member 13 and measuring the air pressure at such points. The tappings 23 are preferably arranged on a line at the centre of the arc of wrap such as indicated on the roller 11 at 24 in Fig. 1.

The sleeve 18 can be formed by wrapping a sheet of material tightly around the support member 13 and joining the ends thereof in overlapping relationship.

The support member itself can be formed by wrapping a sheet of perforated stainless steel around a former and butt welding or overlap welding the ends together.

The idler roller according to the present invention presents a low inertia, low friction bearing surface to the web 10 transported thereby. Additionally, the web can be steered by adjusting the mountings of the shaft 1 6. As it is possible to derive measurements of the tension in the web 10 across the width thereof by means of the tappings 23, such steering could be effected automatically in response to detected changes in pressure.

If desired more pressurised fluid could be delivered over the contact arc of web of sleeve further to cushion the web 10 in its transport over the roller.

Claims

1. An idler roller comprising a cylindrical support member, having an inlet at one end for fluid under pressure, a passage therein permitting fluid to be fed to and through holes in the cylindrical surface thereof, and a substantially fluid impermeable sleeve forming a tight fit over at least part of the cylindrical surface of the support member such that when fluid is introduced to the support member, the sleeve is expanded thereby so as to be freely rotatable on the support member substantially without friction.

2. A roller as claimed in claim 1 wherein adjustable end flanges are provided on the support member and arranged adjacent the ends of the sleeve to reduce the escape of fluid therefrom.

3. A roller as claimed in claim 1 or 2 wherein the support member comprises a porous tube of a material such as sintered- bronze.

4. A roller as claimed in claim 1 or 2 wherein the support member comprises a stainless steel perforated sheet, wrapped about an appropriately dimensioned former and butt welded or overlap welded to form the tubular support member.

5. A roller as claimed in any previous claim wherein the sleeve is a flexible film of metal, plastics material or other non-porous substantially impermeable material extensible under the action of fluid pressure to provide a clearance fit on the support member.

6. A roller as claimed in any preceding claim wherein the support member is provided with one or more tappings preferably along the centre line of an arc of contact of a web to be supported, whereby fluid pressure may be measured at the or each tapping.

7. A roller as claimed in claim 6 further including pressure measuring means connected thereto and indicative of the tension in a web supported thereby.

8. An idler roller substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.