GB2073715A - Method of buckle-folding work and turn printed sheets - Google Patents

Abstract

In a method of buckle-folding work and turn printed sheets 3, the sheets are cut longitudinally at 4 and during passage through the buckle folding unit 5, 6 arranged downstream of the cutting device, only one of the resultant sheets is folded, e.g. at 5, 7, 8, the adjacent one passing through the part 6 of the folding unit 5, 6 and being folded in the required manner subsequently in at least one following folding unit 10, 11, 12. <IMAGE>

Description

SPECIFICATION Method of buckle-folding of work and turn printed sheets The invention relates to buckle-folding of work and turn printed sheets (one-up, two-up or multiple-up) in which the sheets are cut along at least one cutting plane extending in their direction of motion, and in which the ups thus obtained are guided through a corresponding number of folding units.

A work and turn sheet is printed on one half thereof with the composed matter for the obverse side, whereas it is printed on the other half with the printed matter for the reverse side of a single sheet to be printed upon. The other side of the sheet exhibits identical impressions, the only difference residing in the fact that the printed areas are arranged in rows in a reverse manner.

Printing is effected in such a way that the sheet to be printed is provided by the printing cylinder with impressions for the obverse and the reverse side, respectively, which are arranged side by side, whereupon the sheet is turned by 1 800 about its direction of motion, the sheet finally being provided with identical impressions on its reverse side.

Multiple-up sheets, for example four-up sheets, six-up sheets, etc., are structured accordingly and are made in corresponding manner. This method of printing a multiple-up sheet by the work and turn method, with the sheet being printed on both sides, have been known for a long time; it affords the advantage that it requires the use of a relatively small number of printing plates only.

The sheets printed in the manner described are collected in stacks and separated by cutting to obtain individual sheets which are printed on both sides. Subsequently the individual sheets are folded successively in the required manner. In view of the fact that the work and turn sheets are first cut to produce individual sheets, whereupon a multiple number of individual sheets have to be folded, the time saved by the printing of work and turn multiple-up sheets is practically lost.

In the German Patent Specification No. 1 6 11 350 there has already been described a method of the type indicated above in which, for the purpose of simplifying and espediting the handling of work and turn two-up sheets, a folding machine is used which has disposed upstream of its draw-in rollers a cutting device serving to cut the sheets along a plane extending in their direction of motion. The folding unit disposed downstream of the cutting device comprises two buckle plates disposed in mutually parallel planes, each buckle plate having only one entrance extending towards one side only of said cutting plane, said entrance having associated therewith a diverting surface extending towards the other side of the cutting plane. In this case, said entrance of said one buckle plate is disposed opposite the diverting surface of the other buckle plate.In the case of the known folding machine, the single-up sheets printed by the work and turn method which are cut by means of said cutting device are folded in different directions so that the sides provided with identical impressions, for example with the reverse side impressions, will always be facing inwardly.

In the case of the known folding machine, the work and turn sheet delivered by the alignment table is passed through the cutting device which severs it into two parts. These parts are passed as single-thickness sheets between the first pair of folding rolls. One half of the sheet is directly introduced into the upper buckle plate, whereas the second half of the sheet is diverted by a sheet deflector, passed through another pair of folding rollers and the introduced into the lower buckle plate. The first sheet, which has to travel a shorter distance, arrives first at the stop in the upper buckle plate and is then folded by the second pair of folding rollers, through the nip of which it is passed as a double-thickness sheet.At the same time the second part of the sheet is passed as a single-thickness sheet through the second pair of rollers, thus losing its accurate guidance just as the first sheet passed the same pair of folding rollers as a double-thickness sheet.

Shortly thereafter the first fold should be formed in the second part of the sheet after it has arrived at the stop in the lower buckle plate. Therefore, the second part of the sheet can no longer be guided accurately through the second pair of rollers which has been opened by twice the former amount in the meantime, this resulting in folding inaccuracies. In view of this fact the known device for folding work and turn sheets has never found general acceptance. Depending on the surface structure of the paper being handled, a larger or smaller inaccuracy of the first fold is caused.

The fact should also be noted that, where only a single separating cut is produced, the individual sheets separated from one another are spaced apart only very slightly as they are being moved and that they might come into mutual contact, this possibly causing deflection of the sheets. For this reason, it has been general practice to employ a strip cutting device which, however, introduces certain additional disadvantages such as higher cost, difficulty of adjustment, longer setting times, very difficult removal or discharge, respectively, of the cut strips having the thickness of a single sheet, larger consumption of paper, etc.

The problem underlying the invention is to provide a method of buckle-folding work and turn printed sheets, which method, while requiring the least possible amount of machinery, ensures accurate folding of the sheets after separation thereof.

This problem is solved in accordance with the invention by providing for at least one part of the sheet to be folded while it passes through the folding unit disposed downstream of the cutting device, providing for the next adjacent up sheet to pass the portion of the folding unit associated therewith without this sheet being folded, and providing for said sheet to be folded in the required manner in at least one of the following folding units.

Since in the method of the invention the separated sheets are handled by completely independent chains of folding units and because the folding rollers of the folding unit disposed immediately downstream of the cutting device are not required to accept materials of different thickness, it is possible by employing the method of the invention to ensure satisfactory and accurate folding without any considerable increase in the amount of machinery required. In connection with this, it is possible to separate each work and turn sheet by a single cut.The existing folding machine designed to fold work and turn printed sheets may be employed for cutting and folding the one sheet or up, whereas the part of the folding machine which is associated with the other sheet is adjusted in such a manner that the sheet passes it without being acted upon, i.e. without being folded, with the pair of draw-in rollers affording a sufficient driving force. The required folding action is then performed by a folding unit disposed downstream of the folding unit mentioned first, it thus being possible to form a satisfactory fold.

The invention will be explained in greater detail with reference being taken to the single figure of the drawing in which there is shown diagrammatically an embodiment of a device for carrying into practice the method of the invention.

The folding machine 1 comprises a feeder 2, on the upper side of which the work and turn printed sheets 3 are fed beneath a cutting blade 4 which separates the two-up sheets into two parts. The one part or up is introduced into section 5 of the folding unit 5, 6 which is arranged immediately downstream of the cutting device 4 so that the first fold or one more parallel fold are folded whereupon a perforating step is performed for the second fold (crossfold); finally the perforating line for the second fold is produced. In the folding unit 7, which is arranged at right angles to the folding unit 5, 6, the second fold (crossfold) is folded and finally the score lines or spine perforations for the third fold are formed. Another folding unit 8 disposes at right angles to folding unit 7 effects the third fold.

The other up is passed through the adjacent part 6 of the folding unit 5, 6. Should the other up be folded in this section 6, an unsatisfactory fold would result. In order to avoid this, section 6 of the folding machine 1 is adjusted in such a manner that the other up will pass section 6 without being folded and is fed to a folding unit 10 via a transfer table 9, the first fold or one more parallel fold being folded there in the required manner with the second fold (crossfold) being perforated. Another folding unit 11 is disposed at right angles to folding unit 10 to make the second fold. After the scores or spine perforations for the third fold have been formed in the folding unit 10, the folded sheet is transferred to another folding unit 12 disposed at right angles to folding unit 11, folding unit 12 serves to fold the third fold.

Employing the method of the invention, it is not only possible to handle two-up sheets as described in the foregoing but also multiple-up sheets may be handled by extending the device or folds in a corresponding manner, i.e. by arranging a corresponding number of chains of additional folding units or folds downstream of the folding unit which is supplied by the cutting devices.

Claims (1)

1. A method of buckle-folding of work and turn printed sheets in which the sheets are cut along at least one cutting plane extending in their direction of motion, and in which the up sheets thus obtained are guided through a corresponding number of folding units, characterized in that, during passage through the folding unit arranged downstream of the cutting device, at least oneup sheet is folded and that the adjacent up passes through the part of the folding unit associated therewith without being folded, whereupon said up is folded in the required manner in at least one folding unit.