BACKGROUND OF THE INVENTION The present invention relates to devices in connection with the paper-lining of flat ob- jects. In paper-lining, two sheets, often one cardboard or corrugated board sheet and one printed paper sheet, one of the sheets being coated with adhesive, are fed to a joining point and are joined together by aid of rolls or rollers.

If the other side of the cardboard or the corrugated board also is to be lined with a paper sheet, which is often a requirement for signboards which are to be placed in a shop to provide advertising on both sides thereof, and to avoid bending of the sheets due to the sheets only being laminated on one side, it is conventional to collect the paper-lined sheets, turn them, and to feed them into the paper-lining machine for paper-lining them on the other side. Usually, this operation is performed manually, which is often burden- some and inconvenient. Moreover, the second paper-lining should preferably be made relatively soon after the first one, in order for the sheets not to bend, which otherwise renders the second paper-lining more difficult.

This is also the case if an additional sheet of cardboard is to be lined to the previous sheets, i. e. for all operations where more than two sheets are to be joined together.

As to rate of production, for conventional paper-lining machines, it is limited to the maximum feeding rate of which the machine is capable. If a higher capacity is required, additional paper-lining machines must be procured. In order for such an investment to pay off, that capacity requirement should not only exist during production peaks, due to the investment cost being relatively high.

As a conclusion, there is a need for a flexible production equipment which fulfils differ- ent requirements and production capacities, with a limited number of paper-lining ma- chines.

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a device in connection with paper- lining of sheets, which solves a numeral of different paper-lining requirements and pro- duction desires. According to a first aspect of the invention, this is obtained with a de- vice characterised in that the device is provided with at least three sheet guides, and with means capable of feeding sheets from two or more sheet guides, as desired, to the press unit, for paper-lining the sheets.

According to a second aspect of the invention, there is provided a device characterised in that means for coating one side of the sheets with an adhesive, are arranged in con- nection with at least two of the sheet guides.

According to an additional aspect of the invention, there is provided a device character- ised in that at least one of the means for transmitting sheets to the sheet guides is adapted to transmit two sheets, the sheets being arranged on top of each other.

Several advantages are obtained by the device according to the invention. Several dif- ferent operations may be performed depending on requirements, such as single paper- lining, double paper-lining and/or increased capacity of the machine, with a single pa- per-lining machine. For double paper-lining, the burdensome and labour demanding turning and re-feeding of single paper-lined sheets for paper-lining them on the other side, is eliminated, thanks to the device being equipped with at least three sheet guides and at least two adhesive works. This enables the paper-lining on both sides of a carrier sheet to be performed in a single operation.

As to single paper-lining, the capacity can be increased to the double when the device enables feeding of two sheets at the same time, above and below each other, as a unit, and that this unit is covered by a top coat layer in one and the same operation.

These, and additional, aspects of and advantages with the present invention, will be ap- parent from the detailed description of a preferred embodiment, and from the enclosed claims.

SHORT DESCRIPTION OF THE FIGURES In the following description of a preferred embodiment, there will be referred to the enclosed figures, where

Fig. 1 is showing a side view of a device according to the invention, and Fig. 2 is showing a detailed view of a press unit which is part of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT The device according to the invention, which is shown in Fig. 1, comprises a press unit 10, which will be described in connection with Fig. 2. The press unit 10 comprises an end stop or holder-on 12, which extends across the feeding direction M of the device.

The end stop 12 is adapted to be displaced in a vertical direction by aid of a suitable means (not shown). Upstream the end stop 12, as seen in the feeding direction, a slide plate 14 is arranged, which plate is intended to guide fed sheets towards the end stop 12.

The feeding means for the sheets will be described below. The slide plate is also acting as a holding-up tool 15 for a presser foot 16. The presser foot 16 too is extending across the feeding direction M, and this too is adapted to be displaced in the vertical direction.

The presser foot 16 is arranged, in relation to the end stop 12, so that the presser foot is shoved down immediately ahead of the end stop.

Downstream the end stop 12 and the presser foot 16, the unit is provided with two press rollers 18, which are arranged above each other, the upper roller being displaceable in the vertical direction, in order to adjust the press force them between. The rollers are preferably made of a relatively elastic material.

The device also comprises three sheet guides, an upper sheet guide 20, an intermediate sheet guide 54 and a lower sheet guide 60, and sheet feeders 22,50 and 58, respectively, arranged in connection with the corresponding sheet guide. Referring to Fig. 1, there is shown an upper sheet feeder 22 in the right part of the figure. The sheet feeder 22 com- prises a flat plate 24, on which a stack of top sheets are placed. The plate 24 can be suc- cessively elevated when the sheets are taken off. The sheet feeder 22 also comprises picking and feeding means 26, e. g. in the form of vacuum suction cups capable of lifting the front edge of the uppermost sheet and leading it onwards to a driven roller 28.

Spring loaded press wheels 29 are pressed against the roller, to provide a nip them be- tween, which enables the picked-up sheet to be fed onwards.

The upper sheet guide 20 is arranged downstream the roller. It has first part 20a, which extends essentially horizontally, as seen in the feeding direction. The first part com- prises two shafts 30,32 which are rotatably journalled in bearings. One of the shafts is driven by a suitable motor. A number of rolls 34 are arranged on each of the shafts.

Each of the rolls is provided with a clamping lock, which, at activation, enables the rolls

to be displaced along the shafts. When the roll is let go, it is locked against rotation and displacement. The rolls on the respective shaft forms pairs, between which there is ar- ranged drive belts 36, which belts are capable of driving the lower sheets ahead. The sheet guide 20 is provided with a longitudinal holder-on, not shown, which holder-on is displaceable across the feeding direction M. The rolls 34 on the shafts are suitably dis- placed so that the belts 36 are not running parallel to the feeding direction, but with an angle against the feeding direction, so that the sheets, when they are fed forward, are also somewhat displaced side-wards, towards the longitudinal holder-on.

The second part 20b of the upper sheet guide 20 is inclining slightly downwards to- wards the press unit 10, which is designed as a flat table. The second part 20b comprises a number of driven rollers 38, which are immersed into the table so that their upwards directed cylinder surface is arranged in the plane of the table, Fig. 2. The uppermost roller, as seen in the feeding direction M, is driven by aid of a suitable motor. The drive is transmitted to the other rollers by aid of belts, not shown, to make all of the rollers rotate with the same velocity. Every roller 38 is provided with a number of press rolls 40. Flat plates 39 are arranged between the rollers 38. The second part 20b of the upper sheet guide 20 too, is provided with a longitudinal holder-on 42, which is displaceable across the feeding direction. The rollers 38 are slightly turned, in the shown embodi- ment, so that the normals of the rotation axis's are forming an angle against the feeding direction, in order to also displace the fed sheets in a side-wards direction, towards the right longitudinal holder-on 42.

The intermediate sheet feeder 50 is designed in the same way as the upper sheet feeder 22. Its picking and feeding means 52 is, however, designed to pick one sheet or two sheets, as desired. When two sheets are being picked, they are arranged on top of each other, and are fed forwards as a unit. An intermediate sheet guide 54, which is designed in the same way as the first part of the upper sheet guide, is arranged after the picking means. The intermediate sheet guide 54 too, is provided with an adhesive works 56, for coating with a suitable adhesive on the top side of the sheets which are being fed in this sheet guide. The sheet guide is, moreover, provided with a longitudinal holder-on 57.

The lower sheet feeder 58 too, is of the same design as the upper sheet feeder 22, and connects to the lower sheet guide 60. The lower sheet guide 60 is provided with an ad- hesive works 62 for coating with a suitable adhesive on the top side of the sheets which are being fed into this sheet guide. The lower sheet guide 60 is, after the adhesive works 62, designed in the same way as the second part 20b of the upper sheet guide, with the

difference that the press rolls 62 are designed as thin plates, in order not to affect the adhesive coated sheet too much.

The device is moreover equipped with transmitters of different types, and a process unit which deals with the information from the transmitters, and controls the different op- erational functions of the device (not shown).

The device is intended to operate as follows.

Lamination of two sheets, single paper-lining This is conventional paper-lining of two sheets, often one top coat layer, i. e. a sheet with some type of printed information, and a carrier sheet, which often is thicker than the top coat layer. The upper sheet feeder, is charged with top coat layers, and the in- termediate, or lower, sheet feeder is charged with carrier sheets. The device is started, whereby sheets are being picked from the two sheet feeders and are being fed forward along the sheet guides, towards the press unit. The sheets are, during the feeding move- ment, being registered in the side direction by aid of the longitudinal holder-on's on the sheet guides. Moreover, the top side of the carrier sheet is being coated with adhesive when it passes through the adhesive works. Finally, the sheets are being fed forward against the holder-on in the press unit, where they are registered in the front edge too.

The two sheets are now registered in relation to each other, by being positioned both in the side direction and the longitudinal direction. The presser foot 16 is activated and moves vertically downwards and presses the front edges of the sheets together. The pressing is taking place during a certain prechosen time period, depending on which adhesive is used. When the pressing is finished, the presser foot 16 is raised, the end stop 12 is lowered, and the feeding of the top sheets commences. The two sheet are, thus, fed forwards between the press rollers, and are joined together completely.

Lamination of three sheets, double paper-lining Lamination of three sheets is often performed if top coat layers are desired on both sides of a carrier layer, for e. g. advertising sign boards, which are to hang in a shop. In this case, the upper and the lower sheet feeder is charged with top coat layers, and the inter- mediate sheet feeder is charged with carrier layers. As is described above, sheets are being picked by the sheet feeders and are being fed forwards by the sheet guides, while at the same time being registered along their side edges. In this case, both the top side of the carrier sheet, which is being fed forwards on the intermediate sheet guide, and the top side of the top coat layer, which is being fed forwards on the lower sheet guide, is being coated. The press rolls 62 for the lower sheet guide have the purpose of ensuring a

good forward feed of the sheets, when this sheet guide is slightly upwards inclined to- wards the press unit. The sheets are then fed to the press unit and are registered in rela- tion to each other and joined together in the above mentioned way, whereby the carrier layer is covered on both sides with top coat layers.

Lamination of two sheets, double capacity At paper-lining, the time requirement for the joining of the sheets establishes the limit for the capacity of the machine. In order to increase the capacity, using only one single paper-lining machine, several sheets have to be paper-lined at the same time. This is done by using all three sheet feeders. Top coat layers are charged into the upper and lower sheet feeders, and carrier sheets are charged into the intermediate sheet feeder.

The sheets from the upper sheet feeder and the lower sheet feeder are being picked as is described above. In the intermediate sheet feeder, two sheets are being picked at the same time, so that they are arranged on top of each other on the sheet guide. The sheets are fed forward, the lower sheet being coated with adhesive on its top side. In the inter- mediate sheet guide, the top side of the uppermost sheet is being coated. The sheets are fed forwards to the press unit and are joined together as is described above, the two car- rier layers being covered with one top coat sheet each.

It is to be understood that the invention is not limited to the embodiment described above and shown in the figures, but may be modified within the scope of the enclosed claims. Accordingly, the sheet feeders and the sheet guides may be designed in other ways, to enable picking, feeding and registering of the sheets before the paper-lining.