GB2166420A - An improved side-lay system - Google Patents

Abstract

A side lay mechanism effects lateral registration of a sheet in a sheet handling machine e.g., a printing machine. The mechanism comprises means for advancing the sheet, means for effecting lateral movement of the sheet while it is being advanced and means for controlling the extent of said lateral movement. Thus the sheet 1 advanced through a nip between driven roller 2 and pinch rollers 3 mounted on shaft 5 which also mounts a cam follower 6. Engagement of the cam follower 6 with cam 7 on printing roller 8 causes a transverse shift of pinch rollers 3 to register sheets 1 against edge 9. <IMAGE>

Description

SPECIFICATION An improved side-lay system This invention relates to any machine such as a printing, folding, collating, counting or cutting machine in which successive sheets or board blanks are to be processed in precise relation to either side edge. In particular, but not exclusively, it relates to the registration of paper sheets in printing presses so that the printed image is positioned in a precise repeatable relationship to one of the sides, i.e. one of the edges which are parallel to the direction or motion through the machine.

The majority of previous mechanisms for this purpose operate by bringing the sheet to a halt, releasing the forward drive mechanism and then applying a gentle sideways force which draws the sheet sideways against a fixed lateral stop. This force must be so applied and the material so held and constrained that when the material reaches the stop its movement ceases and it is held steady without buckling. It is then ready to be further advanced into the machine. This is a delicate operation requiring fairly intricate, closely adjusted, mechanism, particularly at higher speeds. It also has the serious disadvantage of limiting speed, since the sheet must be retarded to rest and re-accelerated. It is particularly inappropriate in machines which do not require a longitudinal registration and therefore have no other reason for bringing the sheet to rest.

The present invention, a continuous feed side lay mechanism, is also applicable other mechanisms in that it avoids the need for more complex and expensive operations such as a feed (or lay) table.

It is the object of the present invention to guide the material into the correct path while it continues to move (at any speed) in the drive direction, and to do this by means of a simple and compact mechanism which can, if required, be added to existing machines which have no side register mechanism at all, and which therefore rely on precise positioning of the material to be processed and are of limited accuracy.

The present invention provides a device for effecting lateral registration of a sheet in a sheet handling machine which comprises means for advancing the sheet, means for effecting lateral movement of the sheet while it is being advanced and means for controlling the extent of said lateral movement. The means for advancing the sheet and/or means for effecting lateral movement are advantageously positively driven guide means, e.g., a drive roller or rollers. Bytheterm "positively driven" is meantthat the means referred to is provided with means for driving it. Alternatively, reliance may be placed on gravitational forces, if desired in cooperation with guide means, e.g., an idler roller or rollers.Advantageously, the coefficient of friction between the advancing means and the sheet is greater for movement of the sheet in the direction in which it is being advanced than for lateral movement, and advantageously the coefficient of friction between the means for effecting lateral movement and the sheet is greater for movement in the lateral direction than is the coefficient of friction between the advancing means and the sheet.

More especially, according to the present invention, the sheet is taken by a feeder, which may be a conventional suction feeder or alternative means, which places the leading edge between a drive roller (above or below the sheet) and free-running pinch rollers which press against the drive roller. The sheet is thus drawn forward as a result of friction between the drive roller and the material. During this movemenu the pinch rollers are urged sideways across the material by means of a cam or means actuated in some other way such as magnetically or fluidically.

The relative frictions between the drive rollers, material and pinch rollers must be such that: (1) the material will slide on the drive roller in the lateral direction whilst maintaining positive grip in the drive direction; (2) the pinch rollers will slide on the material in the lateral direction, but with greater friction on the material than the drive roller on the material, thus creating greater pull by the pinch rollers which also maintain positive grip in the drive direction.

Thus when the pinch rollers are moved laterally, they take the sheet with them, causing it to traverse laterally whilst still moving in the drive direction. A side stop is provided which limits the movement of the sheet and controls its final position. Any further movement of the pinch rollers will cause them merely to slide against the material and prevent buckling.

To assist achievement of the correct friction coefficients, small transverse teeth or other means may be provided on the drive roller. This causes the friction of the roller on the material to be greater in the drive direction than laterally. Serrations may also be added to the pinch rollers as a means of limiting their frictional force laterally on the paper to prevent buckling.

Interchangeable rollers may be adapted to cater for materials with special friction coefficients resulting from particular surfaces or with different surfaces on each side.

If the feed mechanism promotes a change in plane in the drive direction of the material being processed as it passes over or under the drive roller, the curve which this induces in the material makes the sheet stiffer and therefore amenable to greater sideways forces without danger or buckling.

An embodiment of the invention for printing purposes will now be described with reference to the accompanying drawings, in which Figure 1 is an isometric view of the whole system and Figure 2 is a cross-section. In this particular embodiment two pinch rollers are shown positioned above the drive roller.

A sheet of material 1 is advanced by a feeder (not shown) and is nipped between drive roller 2 and the pinch rollers 3, which in turn are carried on arms 4 mounted on the transverse shaft 5. Rollers 3 are urged towards roller 2 by a spring 5A acting on shaft 5 which is free to slide axially.

Cam follower 6 is also mounted on shaft 5 so that it will be moved sideways when engaged by the cam 7 mounted on the printing cylinder 8. The cam is timed so as to cause this movement after the leading edge of the sheet has been nipped by rollers 3 but before the leading edge reaches the cylinder 8.

When this movement takes place, shaft 5 and rollers 3 will also move and will urge the sheet 1 towards the fixed (but adjustable) stop 9. The stop incorporates top and bottom guide plates 11 and 12 which are very close to the material and prevent buckling. The stop itself is made of smooth wearresisting material, such as hardened steel or ceramic, and is mounted on transverse bar 23 so as to be conveniently and accurately adjusted sideways. Optionally a similar stop is provided on the other side of the machine, and cam 7A is provided so that the sheet may be registered to the opposite edge if desired.

After the sideways movement has been completed, it is necessary for the rollers 3 to return to their original position. This may for example be achieved by an extension of cam 7A or by means of the return spring 13. An additional cam (not shown) may be used to rotate shaft 5 so as to lift rollers 3 clear of roller 2 during this return motion. The return of rollers 3 is only permitted after the material has been held by other means to maintain its achieved position. For heavy gauge paper or board, the leading edge of the sheet may itself separate the rollers 3 and the rollers 2; for light gauge materials, the rollers 3 may be lifted clear of the rollers 2, e.g., by the same or a further additionai cam (not shown).

Figure 2 shows how guide plates 11 and 12 can be positioned so as to impart a curve to the material.

This also directs the sheet towards cylinder 8 at the required tangent while the curve which is induced stiffens the sheet laterally.

Both drive roller 2 and pinch rollers 3 are serrated but for different purposes. In the case of roller 2 the objective is to maximize the forward force on the material while minimizing the frictional resistance to sliding sideways. In the case of rollers 3, the serrations are a means of reducing the sideways friction if a correct value cannot be achieved by selection of material from which the rollers are manufactured, or if this is liable to alter due to build-up of material dust etc.

Instead of solid rollers 2 and 3 alternative means may be provided. For example, the roller 2 may be replaced by a belt, preferably a pair of rollers and a belt, thereby providing a greater contact area. In a further embodiment, the rollers 2 and/or 3 may be constructed from thin flexible discs placed side by side with gaps between them. Sideways displacement of the material would then occur through bending of the discs, without breaking the frictional grip between discs and material. If required the discs could be serrated. Another alternative would embody the use of a suction mechanism.

Claims (12)

1. A device for effecting lateral registration of a sheet in a sheet handling machine which comprises means for advancing the sheet, means for effecting lateral movement of the sheet while it is being advanced and means for controlling the extent of said lateral movement.

2. A device as claimed in claim 1,wherein the coefficient of friction between the advancing means and the sheet is greater for movement of the sheet in the direction in which it is being advanced than for lateral movement.

3. A device as claimed in claim 1 or claim 2, wherein the coefficient of friction between the means for effecting lateral movement and the sheet is greater for movement in the lateral direction than is the coefficient of friction for movement in the lateral direction between the advancing means and the sheet.

4. A device as claimed in any one of claims 1 to 3, wherein the means for advancing the sheet is a positively driven means.

5. A device as claimed in claim 4, wherein the advancing means comprises a drive roller.

6. A device as claimed in claim 4, wherein the advancing means comprises a drive belt.

7. A device as claimed in any one of claims 1 to 4, wherein the means for effecting lateral movement of the sheet is positively driven in the lateral direction.

8. A device as claimed in claim 1, substantially as described with reference to and as illustrated by the accompanying drawings.

9. A sheet handling machine comprising a device as claimed in any one of claims 1 to 8.

10. A machine as claimed in claim 9, which is a printing machine.

11. A method for effecting lateral registration of a sheet in a sheet handling machine, which comprises advancing the sheet, effecting lateral movement of the sheet while advancing it, and controlling the extent of the lateral movement.

12. A method as claimed in claim 11, carried out using a device as claimed in any one of claims 1 to 8.