WO1992015514A1

WO1992015514A1 - Sheet feeding device

Info

Publication number: WO1992015514A1
Application number: PCT/GB1992/000353
Authority: WO
Inventors: Christopher Robin Watkiss
Original assignee: Watkiss Automation Limited
Priority date: 1991-02-27
Filing date: 1992-02-27
Publication date: 1992-09-17
Also published as: GB9222093D0; EP0526612A1; JPH05507260A; GB2258906A; GB9104104D0

Abstract

A feed roller (10) especially for feeding sheets of paper, e.g. in a collating machine, is provided with a plurality of holes or recesses (12) wholly or partly through the thickness of the roller so that there will be increased surface area contact with a sheet of paper when the roller makes compressive feeding contact with the sheet. The roller may have ribs (16) on the peripheral surface, preferably of trapezoidal cross-section.

Description

SHEET FEEDING DEVICE

This invention relates generally to devices for feeding sheets of material, and in particular for feeding sheets of paper.

In most paper feed systems rollers are used to advance the paper. In designing appropriate rollers one is looking to achieve reliability of feeding of the paper, wear resistance of the rollers and prevention of damage to the paper. A spongy roller for example may not damage the paper but may have inadequate grip and/or poor wear resistance. Conventionally, ribbed rollers have been used to give additional grip. If one uses a roller having a smooth surface then one has to have a relatively large diameter roller in order to give sufficient surface area contact. This can be a disadvantage in sheet feeding machines where space is limited or where one wishes to keep the volumetric size of the machine as small as possible.

It is an object of the present invention to provide an improved sheet feeding device in the form of a roller and by means of which one can obtain an extended area of contact between the roller and the sheet without increasing the diameter of the roller.

This is achieved in accordance with the present invention by a feed roller for sheet material, comprising a generally cylindrical body adapted for rotation and having a plurality of holes or recesses therein to increase the peripheral surface area contact with a sheet of material when the roller makes compressive feeding contact with the sheet.

Preferably, the holes or recesses are provided around the roller on a common radius from the centre of the roller. The provision of these holes or recesses in the roller enables the roller to be -Δ '

"squashed" against the sheet and thus to provide a larger surface area of contact than in the case of a solid roller of the same diameter.

The holes in the roller may be circular, and desirably taper from each outer side face of the roller towards a central plane through the roller parallel to said outer side faces.

In an alternative embodiment, the roller is provided with holes therethrough which define straight or curved spokes between an inner annular portion of the roller and an outer annular portion of the roller. Particularly with the provision of curved spokes and hence arcuate slots through the roller, one has the possibility of creating variable pressure at the surface of the roller depending upon the direction of rotation of the roller. In other words, variable pressure can be created, depending upon whether the roller is being driven or is freewheeling.

The feed roller of the present invention is particularly useful in a collating machine such as described in our International patent application WO 91/04215.

In order that the invention may be more fully understood, a number of preferred embodiments of feed wheel or roller in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Fig. 1 is a side view of a first embodiment of roller; Fig. 2 is a side view of a second embodiment of feed roller;

Fig. 3 is a detail view of part of the circumference of the roller of Fig. 2;

Fig. 4 is a sectional view through the roller of Fig. 2 taken along the line IV-IV of Fig. 2; and. Fig. 5 is a side view of a third embodiment of feed roller.

A feed roller or wheel in accordance with the invention is indicated generally at 10 in Fig. 1. The roller may be of any suitable material, for example natural rubber- ^■ or a plastics material for example. Natural rubber of 40 Shore hardness may be used for example for feeding sheets of paper. As illustrated, the roller 10 has a smooth peripheral surface 11. The feed roller 10 is here provided with eight equispaced holes 12 around the circumference of the roller. The feed roller here has a central hole 14 therethrough. The provision of the equispaced holes 12 provides the feed roller with a. de.gree of resilience and, depending upon the 'material from which the roller is made, means that when the peripheral surface of the roller is pressed against the sheets being fed there is an increased surface area contact, i.e. an enlarged "footprint". The number and disposition of the holes 12 is a matter of design choice and will vary depending upon the circumstances under which the feed roller is to be used.

In the roller shown in Figs. 2 and 3 the peripheral surface is ribbed. The ribs 16 are of generally trapezoidal cross-section with a short crest 18 and triangular valleys 19 between the ribs. In the illustrated preferred embodiment the bottoms of two adjacent valleys 19 subtend an angle of 9^β at the centre of the roller, and the facing flanks of two adjacent ribs 16 lie at an angle of 60° to each other.

The holes 12 through the feed rollers may be cylindrical and penetrate fully through the rollers, or alternatively, as shown in Fig. 4, recesses may be provided which are tapered and/or terminate short of the median plane of the roller, thus leaving a central web 20 intact. As shown in Fig. 4, each of the recesses 12 has a 5° taper so that the recesses are of increasing diameter from the central web 20 outwards to the outer side faces 22a, 22b of the roller. As an alternative to the provision of equispaced circular holes or recesses within or through the feed roller, one can provide the roller with radial or' arcuate spokes having holes therebetween which will provide the desired resilience and/or compressibility of the feed roller. Fig. 5 shows an embodiment with arcuate holes 24 through the roller between an outer annulus 27 and an inner annulus 28, thus defining spokes 30 between the holes 24. The slots 24 may be of constant width as shown, or of varying width from the inner to the outer end. The use of arcuate holes within the roller is advantageous if one wishes to provide the roller with different properties in each of the two directions of possible rotation of the roller. In other words, the roller would have different properties depending upon whether it is being driven or is free-wheeling.

Although the feed roller of the present invention is particularly appropriate for use in the feeding of paper, it can also be used for the feeding of other sheet material and is not to be regarded as limited just to use with paper.

Claims

-__>-CLAIMS :

1. A feed roller for sheet material, comprising a generally cylindrical body adapted for rotation and having a plurality of holes or recesses therein to increase the peripheral surface area contact with a sheet of material when the roller makes compressive feeding contact with the sheet.

2. A feed roller as claimed in claim 1, in which the holes or recesses are equispaced around the body on a common radius from the centre of the roller.

3. A feed roller as claimed in claim 1 or 2, having holes extending through the full thickness of the body.

4. A feed roller as claimed in claim 1 or 2, having recesses in each circular end face of the body which are axially aligned in pairs with a web of material between each pair at the median plane of the roller.

5. A feed roller as claimed in claim 4, in which the recesses are tapered so as to increase in diameter from the web towards the respective end faces of the body.

6. A feed roller as claimed in any of claims 1 to 4, in which the holes or recesses comprise arcuate or radial slots.

7. A feed roller as claimed in any preceding claim, in which the body has a ribbed peripheral surface.

8. A feed roller as claimed in claim 7, in which the ribs have a substantially trapezoidal cross- section with triangular valleys therebetween and extend lengthwise of the roller.

9. A feed roller as claimed in any preceding claim, made from natural rubber.