GB2385584A

GB2385584A - Roller for web feed mechanism

Info

Publication number: GB2385584A
Application number: GB0204150A
Authority: GB
Inventors: Timothy John Brown
Original assignee: ADVANCED SILICONES Ltd
Current assignee: ADVANCED SILICONES Ltd
Priority date: 2002-02-22
Filing date: 2002-02-22
Publication date: 2003-08-27
Also published as: GB0204150D0

Abstract

A roller 2 for use in a web feed mechanism of an apparatus, such as the paper feed path of a photocopier, comprises an elongate cylindrical body of resilient cellular material, eg. a foamed cross-linked silicone rubber or sponge material, wherein the cylindrical outer surface of the roller is formed with a plurality of longitudinally extending rib formations 4 protruding radially outwardly therefrom.

Description

ROLLER FOR WEB FEED MECHANISM This invention relates to a roller for a web feed mechanism, such as that found in various types of apparatus relying on the passage of web material therethrough, for example photocopiers, printers, fax machines, photographic processing equipment, and such like. The invention also relates to a method and apparatus for producing the roller, as well as to the apparatus in which it may ultimately be incorporated.

Equipment such as photocopiers, printers, fax machines, photographic processing apparatus and such like all rely on the controlled passage of web material through a web feed path. Typically the web material is paper or a film material of some kind. The web feed mechanism includes one or more rotating rotters which grip the web material and guide or force its passage through the feed path. The ability of the roller (s) of the mechanism to precisely grip the web material and accurately deliver it through the path is therefore critical.

Typically these days rollers for paper or film feed mechanisms comprise a cylinder of resilient cellular material, usually extruded synthetic foam rubber, which is mounted fast on an axle or shaft, rotation of which under control of the feed mechanism moves the web material through the feed path. Typically the axle or shaft on which the roller is mounted is biased (by spring-loading) towards the web in order to provide a sufficient gripping effect.

However, conventionally as part of the roller's manufacturing process, it is necessary to abrasively grind down the outer cylindrical surface of the extruded roller by a small amount in order to remove the outer smooth skin and expose its internal cellular structure, because only then are an optimum combination of hardness, resilience and gripping properties of the roller material realised. This requirement for grinding however has several disadvantages: (i) it requires an excess of starting materials to be used in making the roller than is actually

present in the finished product, which is uneconomical, (ii) it leads to wasted material which cannot be reused, and (iii) it requires an extra stage in the manufacturing process, which increases its overall time and cost.

It is thus an object of the present invention to ameliorate at least some of the above-mentioned disadvantages and provide a roller which does not need to undergo surface grinding in order to be usable in a web feed mechanism.

Accordingly, in a first aspect the present invention provides a roller for use in a web feed mechanism of an apparatus, the roller comprising an elongate cylindrical body of resilient cellular material, wherein the cylindrical outer surface of the roller is formed with a plurality of longitudinally extending rib formations protruding radially outwardly therefrom.

The resilient cellular material which forms the body of the roller is preferably a foamed cross-linked silicone rubber or sponge. Examples of such materials and how they are made are well known in the art. These materials are particular suitable for rollers for use in apparatuses such as photocopiers and printers because of their ideal balance of physical properties (hardness, resilience, etc) and their excellent thermal stability over a wide range of temperatures.

Examples of silicone rubber sponge materials particularly suitable for use in the invention are those commercially available from ourselves (Advanced Silicones Limited) under the designations AD24 or AD20.

Central to the present invention is the provision of a plurality of longitudinally extending rib formations protruding radially outwardly from the cylindrical outer surface of the roller. These rib formations in themselves impart to the roller's outer surface the necessary surface properties (particularly the combination of hardness and resilience) to enable the roller to adequately grip the web material and feed it through the feed path, without the need for the internal cellular

structure of the roller material to be exposed by a grinding step in the manufacturing process.

The rib formations preferably extend over substantially the entire longitudinal length of the roller. They are preferably formed integrally with the body of the roller, ie. in the same extrusion process, which is the preferred manufacturing method (see further below about this).

The ribs are preferably equiangularly disposed around the circumference of the roller, yet the number of ribs may vary, depending on the dimensions of the roller and the optimum circumferential spacing of them which may be required for any given application or apparatus in which the roller is to be used.

Generally, however, the number of longitudinal rib formations around the outer cylindrical surface of the roller will be sufficient such that at any given point in the roller's rotation when installed in the apparatus, at least two ribs are in contact with the web material being fed through the feed path, in order that a sufficient degree of controlled movement is imparted to the web material.

Specific examples of the number and spacing of the rib formations of a typical roller according to the invention will be given further below in the specific description of preferred embodiments. However, by way of example, for use in a typical photocopier paper feed mechanism a roller of the invention with an outer diameter of about 2 to 2.5 cm (and an inner diameter of about 7 to 8mm), there may be provided 15 to 25 (eg. about 20 to 21) equiangularly spaced longitudinal ribs, giving a circumferential spacing thereof of about 1. 5 to 2.5mm (typically about 2mm).

The height (radially outwardly from the surface of the roller) and the shape of the rib formations may also be selected according to the precise requirements of the apparatus and the material to be fed through its feed mechanism. Typically

a height of the order of a millimetre (eg. 0.5 to 1.5 mm) will be suitable for many practical applications like rollers for conventional photocopiers and printers. The cross-sectional shape of the ribs may also vary and be selected to give best results in any given practical situation. A simple arcuate (eg. hemispherical or parabolic) sectional shape may be suitable in most practical cases.

A roller according to the present invention, like its conventional counterpart, preferably has a central longitudinal cylindrical bore or channel formed therein of the same order of internal diameter (ID) as the conventional roller, for the purpose of mounting the roller onto a shaft or axle of the web feed mechanism of the apparatus by the same various means. The precise ID will normally be selected according to whether an interference fit or an adhesive bonding is to be used to mount the roller on to its shaft or axle. The outer diameter (OD) of the roller according to the invention may similarly have the same order of OD as the conventional roller, although the OD of the roller of the invention may now be taken to be (ie. defined as) that of the main cylindrical body of the roller, excluding the additional radial width of the ribs.

Rollers according to the present invention may be made in the same way as conventional rollers of the same type, which in preferred practical cases is by an extrusion method in which the mixture of the relevant starting materials (as is conventional) is fed under pressure through a die of the appropriate size and shape, preferably with a centrally mounted spigot to form the central bore, during which procedure the mixture expands (eg. by up to around 30%), crosslinks and cures, forming the required shaped cylindrical body which can then be cut into rollers of the required length.

In the context of the present invention, however, the extrusion die is of a novel shape, such as to form the longitudinal rib formations protruding from the outer surface of the roller as it is extruded from the die. Thus, in a second aspect the

present invention provides a die for forming by extrusion a roller according to the first aspect of the invention, the die having a head portion of generally circular cross section but with a plurality of radially inwardly protruding indentations or recesses in the inner wall thereof.

Of course, preferred features of the number, spacing, depth and shape of the indentations/recesses of the die of this aspect of the invention mirror the corresponding preferred features of embodiments of the roller of the invention, as discussed above.

In a third aspect the present invention provides a method of making a roller according to the first aspect of the invention, the method comprising extruding a resilient cellular material-forming composition through a die according to the second aspect of the invention.

Rollers according to invention may be incorporated in any apparatuses which rely on a web feed mechanism. Thus, in a fourth aspect the present invention provides an apparatus comprising a web feed mechanism, the mechanism including one or more rollers according to the first aspect, or made according to the method of the third aspect, of the invention.

Such apparatuses according to this fourth aspect of the invention may accordingly be for example photocopying machines, printers of various types (including ink-jet and laser printers), fax machines, photographic or film processing equipment, or any other equipment including a web feed mechanism.

Any number of rollers according to the invention may be used in such apparatuses, depending on the nature and construction of the web feed mechanism and its overall requirements. The one or more rollers will generally be mounted using well known techniques on a conventional rotatable shaft or axle, either by a simple interference (ie. friction) fit or by adhesive (eg. a silicone adhesive).

For a better understanding of the present invention and to show more clearly how it may be carried into effect, preferred embodiments of the invention in its various aspects will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a preferred embodiment of the roller according to the invention; Figure 2 is an enlarged cross-sectional view of the roller of Figure 1 ; and Figure 3 is an enlarged schematic cross-sectional view of the head of a preferred die according to the invention used to extrude the roller of Figure 1.

Referring firstly to Figures 1 and 2, the roller indicated generally as 2 has the same generally cylindrical outer shape and dimensions as a conventional roller for the equivalent purpose, including a central cylindrical bore 10 to enable it to be mounted (eg. by blowing using compressed air to form an interference/friction fit, or alternatively using eg. a silicone adhesive) onto a shaft or axle, for mounting in a paper feed mechanism of a photocopier for example, or else the web feed mechanism of some other apparatus such as a printer, fax machine or photographic medium processing equipment.

Formed longitudinally along the outer surface of the roller and protruding radially outwardly therefrom are a series of arcuate-shaped ribs 4, which are disposed equiangularly around the circumference of the roller 2. In this particular example of a photocopier paper feed roller with a typical length of about 30cm, there may typically be about 21 ribs spaced apart by a circumferential distance of about 2mm, the ribs having a height of about 1 mm and being of a generally arcuate (hemispherical) shape.

The ribs 4 are formed integrally with the main body of the roller 2 during its extrusion. In this example the material of the complete extruded roller is a silicone rubber sponge material, such as/lAD24" or/lAD20", ex Advanced

Silicones Limited, manufactured from the same mixture of starting materials (cross-linkable silicone composition, fillers, catalyst and blowing agent) and in the same way as conventional rollers made from the same materials. AD24 is a silicone rubber sponge with an apparent density (as measured by BS443 PT 1 Test Method 2) of 24 Ib/ft3, whilst the latter material has a corresponding apparent density of 20 Ib/ft3. Further properties of these silicone materials are available from the company's respective data sheets.

Figure 3 shows schematically the die head used to extrude the body of foamed cross-linked silicone rubber sponge material which is subsequently cut to the required length to form roller 2. The die head 12 has a generally cylindrical mouth 16 (which has a polished inner surface) through which the starting mixture passes under pressure, whilst there is also present, mounted centrally therewithin (as in extruding the conventional types of roller) a bolt-mounted conical spigot 18 (not actually shown as such) for forming the central bore 10 of the roller 2 with a desired ID.

The interior wall of the die head mouth 16 is formed with a corresponding number and distribution of correspondingly sized and shaped indentations or recesses 14 which form the longitudinal ribs 4 on the outer surface of the roller 2 as it is extruded from the die and allowed to expand and cure. The indentations or recesses 14 may be formed in the die wall by any suitable means, for example during the forming/moulding of the die head itself, or subsequently by suitable machining, or even manually using suitable tooling.

It will be appreciated that the above description of preferred features and embodiments of the various aspects of the invention has been by way of nonlimiting example, and various modifications may be made from what has been specifically described and illustrated whilst remaining within the scope of the invention as claimed.

Claims

CLAIMS.

1. A roller for use in a web feed mechanism of an apparatus, the roller comprising an elongate cylindrical body of resilient cellular material, wherein the cylindrical outer surface of the roller is formed with a plurality of longitudinally extending rib formations protruding radially outwardly therefrom.

2. A roller according to claim 1, wherein the resilient cellular material which forms the body of the roller is a foamed cross-linked silicone rubber or sponge material.

3. A roller according to claim 1 or claim 2, wherein the rib formations extend over substantially the entire longitudinal length of the roller.

4. A roller according to any one of claims 1 to 3, wherein the rib formations are formed integrally with the body of the roller.

5. A roller according to any preceding claim, wherein the rib formations are equiangularly disposed around the circumference of the roller.

6. A roller according to any preceding claim, wherein the number of longitudinal rib formations around the outer cylindrical surface of the roller is such that, at any given point in the roller's rotation when installed in the apparatus, at least two ribs are in contact with the web material being fed through the feed path.

7. A die for forming by extrusion a roller according to any one of claims 1 to 6, the die having a head portion of generally circular cross-section but with a plurality of radially outwardly protruding indentations or recesses in the inner wall thereof.

8. A method of making a roller according to any one of claims 1 to 6, comprising extruding a resilient cellular material-forming composition through a die according to claim 7.

9. An apparatus comprising a web feed mechanism, the mechanism including one or more rollers each according to any one of claims 1 to 6.

10. An apparatus according to claim 9, which is a photocopier machine, a printer, a fax machine or an item of photographic film processing equipment.

1 1. A roller, or a die for forming it, or a method of making it, or an apparatus containing it, substantially as described herein with reference to the accompanying drawings.