WO1991008114A1

WO1991008114A1 - Web for web handling apparatus

Info

Publication number: WO1991008114A1
Application number: PCT/GB1990/001859
Authority: WO
Inventors: Robert Wallace
Original assignee: Allprint Graphics Limited
Priority date: 1989-11-29
Filing date: 1990-11-29
Publication date: 1991-06-13
Also published as: GB8926944D0; EP0455799A1; GB2238526B; DE69013891D1; EP0455799B1; GB2238526A

Abstract

A web, e.g. of sign-making stock, is disclosed having a novel configuration of drive holes down each longitudinal edge for engagement by the spaced pins of the two sprocket drive wheels used in web handling apparatus to advance the web into a machine. According to the disclosure, alternating with the sprocket holes (2, 2') down each side of the web (1) are elongated slots (3, 3'), which enable the web to be used with machines of the type described in EP-B-0134064 and which have an extra pin on each sprocket wheel as a means of ensuring accurate registration of the web when being loaded into the machine.

Description

WEB FOR WEB HANDLING APPARATUS

This invention relates to web handling apparatus of the type comprising a pair of sprocket wheels spaced on opposite sides of the machine and which have a plurality pins of projecting therefrom and equispaced around the periphery of each sprocket wheel for engaging with a line of equispaced holes down each side of the web of material which is to be fed through the machine by the drive to the spocket wheels. More particularly, this invention relates to a web of material, usually but not necessarily a web, of sign making stock for use with such apparatus having a line of sprocket holes down each side of engagement by the sprocket wheel of the web handling apparatus.

In the loading of such webs into the web handling apparatus, a problem of alignment can arise, particularly with web handling apparatus of considerable width. In these cases it is often quite easy to feed a new web of material into such a machine in a skew position, i.e. with the two sides of the web out of exact alignment, or out of registration by the spacing of one or two pins.

Various designs have been proposed in the past for obtaining the proper initial alignment of the web in the machine by the position of various registration marks or extra registration holes on opposite sides of the web, possibly engaging with extra registration pins on each sprocket wheel, thus ensuring the correct alignment as the web is loaded into the apparatus.

One such proposal has recently been put forth in EP-B-0134064 by

Gerber Scientific Products Inc. The solution to the problem proposed by Gerber involves providing each sprocket wheel with an extra registration pin, or possibly two extra registration pins between an adjacent pair or adjacent pairs of drive pins, thus providing a visually distinct group of three or five pins, distinguished from the other pins around the sprocket wheel, by virtue of a different spacing therebetween. Preferably, the extra registration pins are located at the mid-point between two adjacent drive pins, so that the visually distinct group of three (two drive and one registration) pins or five (three drive and two registration) pins is distinguished by an interpin spacing of ^D/2 where D is the normal pin spacing, i.e. the normal spacing of all drive pins around the periphery of the sprocket wheel.

Correspondingly, the web for use in the Gerber apparatus has at intervals along the length of the web equal to the circumference of the sprocket wheels an extra registration hole, or as the case may be, two extra registration holes, on the same line as the line sprocket drive holes down each side of the web, and located between an adjacent pair, or two immediately adjacent pairs of drive holes, and again preferably at a spacing of D 2. The web thus has, down each side, at the appropriate intervals corresponding to the circumference of the sprocket wheels, a visually distinct group of three or five holes aligned with each other across the width of the web. Because of the different pin/hole spacing, it is impossible for the loader to load the web into the web handling apparatus, anything other than in the correct registration, since this is the only position in which the web will fit onto the sprocket wheels, i.e. with the extra registration pin(s) engaging the extra registration holes on the opposite sides of the sheet.

The present invention seeks to provide an alternative web configuration which will fit equally well onto the apparatus of the Gerber type, i.e. having an extra registration pin, or possibly two, on each sprocket wheel, in line with and spaced between an adjacent pair, or between two immediately adjacent pairs, preferably at a spacing of ^D/2, although that is quite immaterial as far as the present invention is concerned.

The web configuration of this invention is shown in the accompanying drawing, which is a plan view of a web (1), e.g. a web sign making stock, although the material from which the web is constructed is wholly immaterial to the present invention, of indefinite width, i.e. whatever width is appropriate to fit a particular apparatus, and indefinite length, and having a line of equispaced sprocket drive pin holes (2, 2') down each side and spaced inwardly in distance "d" from the edge of the web. Again the value of "d" is immaterial and will depend on the intersprocket spacing of the apparatus concerned and the overall width of the web. Usually, "d" will be of the order of l-2cms. On the same line as each line of sprocket pin holes (2, 2'), and down each side of the web, are elongated slots (3, 3') equispaced between each adjacent pair of sprocket pin holes (2, 2') having a length "1" (see the enlargement) that is equal to or less than D-2r, where D is the interhole spacing and "r" is the radius of the sprocket pin holes, and a width "2r", i.e. a width that is equal to the diameter of the sprocket drive holes.

When considered along the length of the web, the opposite ends of each slot (3,3') are preferably inwardly arcuate at a radius r' that is preferably equal to r. Thus each of the slots (3,3') is preferably separated from its adjacent sprocket pin holes (2,2') by an arcuate web of material (4,4') having a width "w" measured along the length of the web that is equal to i (D-l). Preferably "w" is at least 2mm to give the web adequate longitudinal strength.

As will be apparent, such a web will fit apparatus of the Gerber type incorporating an extra registration pin or pins on the sprockets in line with and between adjacent sprocket pins.

When loaded with a web according to the present invention, the elongated slots (3,3') will permit the web to be driven quite smoothly through the apparatus in the normal, conventional manner, i.e. by the equispaced drive pins on each sprocket engaging the drive holes (2,2') on the web. The elongated slots (3,3') are simply there to permit the web to run over the extra registration pin(s) on each sprocket wheel, but serve no other purpose. In particular they do not serve the purpose nor the function of the extra registation holes as taught by the Gerber patent, since the slots (3,3') are incapable of distinguishing adjacent pairs of sprocket holes anywhere along the length of the web. The slots (3,3') therefore do not serve any registration purpose or function.

If desired, a registration function can be provided in known manner, by providing an indicator mark at equal intervals along each edge of the web adjacent opposite pairs of drive holes (2,2'). Such an indicator is shown at (5,5') comprising an extra hole at intervals along each edge of the web at a longitudinal spacing equal to the circumference of the sprockets, and at a distance d' from the edge of the web where d' is greater (or less) than d by an amount greater than r + pi, where r* is the radius of the indicator hole. Preferably d' is greater than d+r+r*, i.e. the lines of the indicator holes (5,5') are preferably inset relative to the lines of the sprocket drive holes (2,2'). As will be apparent, the indicator or registration holes (5,5'), or other indicator or registration marks, such as a line or arrow printed at intervals along the length of the web, will be at an intermark spacing of xD, where x is an integer greater than 1 and D is the interhole spacing, corresponding of course to the interpin spacing on the sprocket drive wheels. Preferably of course the intermark spacing will be equal to nxD, where x or D are as defined and is the number of drive pins on each sprocket, or in other words, the intermark spacing is equal to the circumference of the sprocket wheels.

Claims

1. A web of material of indefinite length for use with web handling apparatus of the kind comprising a pair of spaced apart sprocket drive wheels each having a plurality of drive pins regularly spaced therearound for engaging correspondingly regularly spaced drive holes adjacent each edge of web, such sprocket wheels each including an extra registration pin, or pair of registration pins, located between an adjacent pair of drive pins, or between two immediately adjacent pairs of drive pins, said web having a line of equispaced sprocket pin drive holes along the length of the web and inset from the opposite edges of the web for engagement with the sprocket pins of the sprocket drives of the web handling apparatus, and between each and every sprocket pin drive hole down each edge of the web, an elongated slot having a width, in the transverse direction of the web, substantially equal to 2r, where r is the radius of the drive holes, and a length, in the longitudinal direction of the web, which less than D-2r where D is the interhole spacing and r is as above defined.

2. A web according to claim 1, wherein the opposite ends of each slot, in that longitudinal direction of the web are inwardly arcuate.

3. A web according to claim 2, wherein said slot ends are inwardly arcuate at a radius r' where r'=r, thus leaving between each slot and each drive hole an uninterrupted arcuate web of material having a width, in the direction of the web, of "w".

4. A web according to claim 3, wherein w is at least 2mm.

5. A web according to any one of claims 1 to 4, wherein, at regular intervals along the length of the web, and aligned on opposite sides thereof immediately adjacent one of the drive holes in each line of drive holes, there are provided registration indicator marks at an intermark spacing along the length of the web, of xD, where x is a whole number greater than 1, and D is the interhole spacing.

6. A web according to claim 5, wherein the indicator marks take the form of extra registration holes at intervals along the length of the web equal to xD and located on a line inset from each edge of the web, by a distance d' greater than d+r+ri, where d is the spacing of the drive holes from the edge of the web, r is the radius of the drive holes, and r* is the radius of the registration holes.

7. A web according to any of claims 1 to 6, which is a web of sign making stock.