Prior art methods of the above mentioned kind comprises employing of several steps and production of the box in several batches. For example, such a method is known from US-A- 3,236,159. According to the prior art method, the erection of the trough takes place in several complicated steps. At the producer of the troughs, a first preparatory step is made by folding short side walls of a blank over the trough bottom and fixing by gluing in its ends against the respective long side walls. In a second step which is performed at the customer which is going to box the trough, a manual erection takes place of the mentioned folded down short side walls. In a third step, the fixing take place of the portions of the trough side walls which are provided with cold glue. This third step may either oe made manually by in turn performing a manual compressing of tne four corners of the trough, alternatively by machine in that said last mentioned compression is made in a machine related press tool.

Thus, there are many steps that has to be made before the box is in its final erected condition.

The main object with the present invention is therefore primarily to find a method which is environmentally friendly and energy saving and which among other things solves the above discussed inconveniences and instead makes it possible to

produce a box in a single operational step, in which both erection of the blank as well as gluing and sealing of the blank in the erected position may be made in a single operational step. Said object is achieved by means of a method according to the present invention, which is primarily characterized in that the blank is erected and sealed in a common phase after first having applied cold seal glue, i.e. a pressure sensitive, self-adhesive cold seal glue in a printing section for the box material, so that afterwards only folding and compression of the provided blank is needed for producing the box and sealing the blank in the desired erected box state.

A further object of the invention is to provide means that are suitable to be used during realisation of a method for producing a trough-shaped box by erecting and sealing a flat box blank consisting of cardboard, pasteboard or the like, and sealing the blank for producing said box, especially when producing a trough in particular for foodstuffs and where the blank will be provided with folding lines for delimitation of on one hand a trough bottom, on the other a number of from this upwards folding trough side wall parts, wherein the blank is provided with additional folding lines in the trough side wall parts in order to allow adjoining portions of the trough side wall parts to be folded against each other to a double folded position.

Said further object is achieved by means according to the present invention and which are substantially characterized in, that the cold seal glue is arranged for application on the box material by means of a printing machine and that means are provided for folding the produced box blank and compressing it in the areas of the glue application areas. The new technique

departs from the prior art, among other things because the forming of the box is simplified. A glue called "Coldseal" is applied in register upon the box, so that folding and sealing can be performed directly in an erection machine or manually without heating or using locking flaps alternatively hot melt glue/cold glue.

This facilitates forming and reduces the use of heating e.g. for hot melt glue.

When forming boxes by means of heat sealing, heating energy is also used and the plastic is melted together and the box is formed. This production also demands this energy and that e.g. the cardboard material is coated with a plastic layer which makes the box more expensive.

With Coldseal it is not necessary that the material is provided with a plastic layer on one or two sides. The Coldseal glue is applied already in the printing section and blank cutting takes place after which forming is simple to execute. The fact is that material often lack plastic layers, at least on one side of it . In a number of cases of designs of forms, troughs etc., one element is eliminated when producing the box, i.e. the glue. The gluing apparatus is provided with glue applicators which apply e.g. a 4-point box. Gluing with Coldseal results in that only folding and compression is needed in the machine. The application of glue is eliminated.

In other cases, the gluing takes place in erection machines at the customer which is then made by means of hook locking, cold glue or heat sealing. Because the new method for cardboard boxes makes it possible to apply the glue during printing, production is rationalised.

During manual locking and forming like for example could be mentioned pizza boxes, forming is realised by means of hook locking. Also this type of box may be simplified and material may be saved because flaps may be made smaller. Also the box will be more rigid.

The application of the cold seal may preferably be performed in different types of printing presses like especially intaglio but also in modern offset presses with IR- drier etc. The invention is described in more detail in the following, wherein an embodiment is exemplified with reference to the accompanying drawings in which,

Fig 1 is a view from below of a blank, which may be used in the method in accordance with the invention, ' Fig 2 is a perspective view of the blank according to

Fig 1 erected for forming a trough,

Fig 3 is a view from above of the trough shown in Fig 2 in folded condition,

Fig 4 shows a method according to the invention for erecting a blank of the type shown in Fig 1, and

Fig 5 and 6 are views from above of two different types of lids for a trough.

It should however be noted that the invention as well includes methods to manually or in any other suitable way in accordance with the scope of the claims produce boxes simply and functionally, e.g. manually or with the help of a plurality of fingers and formers which guide and position the various parts of the box in the correct desired position and provides compression of the cold seal portions manually or mechanically. Fig 1 shows a flat blank 1 of cardboard provided with the desired folding lines, that is four first folding lines 2

for delimitation of on one hand a trough bottom 3, on the other four from this upwards foldable trough side wall portions, which later exhibit long side walls 4 and short side walls 5, other folding lines 6, 7 and 8 for forming double folded trough side wall parts of the blank, which enables erection of the long side walls 4 and the short side walls 5, third folding lines 9 and 10 for enabling folding out an edge flange, so called edging, 11 and 12 respectively along the long side walls and the short side walls respectively. Fourth folding lines 13 are arranged in order to allow folding the trough together from an erected position. The blank 1 is shown in Fig 1 from the "underside" i.e. that side which will form the outside of the erected trough.

The other folding lines 6, 7 and' 8 form together a fold, web-corner, at each corner of the trough, wherein the folding lines between them form two mutually equally large portions 14a and 15a (respectively 14b, 15b respectively 14c, 15c respectively 14d, 15d) of the blank, which are intended to be folded outward from the trough during erection of the blank, in towards each other and in towards an appurtenant, adjacent zone 16 on the respective wall part 4, so that the blank 100 forms a completed erected and formed trough la according to Fig 2. Also another folding method is enabled.

A portion of the edging 11 is in Fig 2, for pedagogical reasons cut away, in order to show how two such portions 14a and 15a are folded together against each other, with the portion 14a being in contact {almost hidden in Fig 2) against the respective zone 16 (completely hidden in Fig 2) at the respective wall part 4. The described blank is in itself previously known from

EP-A-0178730. According to the prior art technique, the portions

14 and 15 and the wall part zone 16 are attached against each other by means of heat sealing, so that the trough la is fixed in the erected position.

The in Fig 2 erected and ready trough may if necessary be folded together to a flat state la' , see Fig 3, and is transported to the client which is going to box the trough.

According to the present invention as illustrated in Fig 4, the technique for erecting the trough is simplified in that the trough manufacturer instead of performing the three steps according to Fig 1, 2 and 3 only has to perform step 1 according to Fig 1.

According to the invention, the trough manufacturer may send the blank in unfolded form, see Fig 1, to the customer that then oneself both erects, forms and glues ^■ the trough in a single step. I.e. that the customer then itself without heat sealing and hot melt glue only by pressing together the web-corners both erects, forms and glues the trough in a single step, see Fig 4. The blank 100 shown in Fig 4 has in the disclosed embodiment exactly the same shape and folding lines of the same kind as the blank 1 in Fig 1. The only difference is that the trough manufacturer in Fig 4 has provided the outside of the portions 14a-d and the corresponding surface of the wall part zones 16 with a coating of a pressure sensitive, self-adhesive cold sealing glue, cold seal. This coating is supplied in the same production step where printing of the blank decoration takes place, wherein special plates of BASF LW-material are used, which enable handling of cold seal without adhering without interference with production.

One example of such a cold glue, i.e. cold seal glue is mentioned in the above-mentioned US-A-3, 236 , 159. Another such a cold-glue might be a water based cold sealing glue acrylate and

natural rubber, which is used under the trademark KOLD-LOK for cold sealing of boxes of plastic film, aluminium foil and metallized film for foodstuff and confectionery products.

Said glue types has the quality that two glue surfaces of the blank immediately adheres against each other, if they come into contact with each other under a certain compression. On the other hand, no adherence occur if such a glue surface of the blank does not come into contact with an unglued surface of the blank. This implies that several such glued blanks 100 may be stacked onto each other during transport without adhering to each other, if the blanks are turned towards the same direction, because the two glue surfaces 14a-d and 16 are positioned on the same side which shall form the outside of the trough.

When the customer wants to erect "a trough (see Fig 4) a blank 100 mounted in accordance with the shown embodiment between two form pressing parts, which are composed of on one hand a female part 17 which is composed of a first, stiff metal form, and which has an internal form face corresponding to the desired external shape of the trough, on the other by a male part 18 which is adapted to the internal form face of the female part, which male part is composed of a second, stiff metal form which may be sunk downwards into the female part 17.

By pressing down the male part 18 into the female part 17, the blank 100 is forced to adapt itself to the internal form face of the female part 17, i.e. fold itself along the folding lines 2 and 6 - 8, so that the portions 14 and 15 are forced out behind the respective wall part zone 16, and forming a fold, which is pinched between the female part and the male part 18, so that the portions 14a-d are pressed with pressure against the respective wall part zone 16, so that the glue surface on the

portion 14a-d adheres to the glue surface at the respective wall part zone 16.

In order to facilitate handling of the male part 18, it is provided with a handle 19 which is rigidly connected to the male part 18.

Both the erection of the blank and the gluing of this blank thus is performed in one and the same step, and without any supply of heating energy.

The male part 18 is provided with a peripheral, somewhat downwards sloping edge flange 20, which causes the edge flanges 11 and 12 of the trough to be forced to fold outwards and somewhat downwards, so that the fibres of the material are broken when the male part 18 presses the blank 100 into the female part 17. Thus the female part 17 and the male part 18 together form a sort of form pressing tool, which in one single step both erects the blank 100 to a trough shape and fixes the tray in erected position by means of the forced gluing of the portions 14 and the wall part zone 16 against each other. The ready trough gets according to the invention the same appearance as the trough la according to Fig. 2.

After the customer has filled the erected trough, he seals it by means of a suitable lid, e.g. a lid 21 according to Fig 5, which composes a part which is continuous with the blank 100. Alternatively, he uses a separate lid 22 according to Fig 6.

Please observe that the two against each other folded portions 14 and 15 in each fold are maintained against each other without the need for applying any glue between them. Moreover, a glue surface between the portions 14 and 15 would have been very inconvenient, because this would have meant that

not only outwards facing portions, but also internal portions of the blank would exhibit glue surfaces, which accordingly would render difficult or make impossible stacking of blanks upon each other. At the shown embodiment, the respective fold 14, 15 contact against the respective wall part 4 outside. Alternatively, it is possible in accordance with the invention to instead let the folds 14, 15 be folded in against the trough and bear on the inside of the respective wall part 4. In the last case the outside is instead glued on to the two portions 14a-d and 15a-d, so that the two portions of said folds adhere to each other. In this case, no gluing is needed of the inside of the wall part zone which the fold 14, 15 is supposed to abut. This depends upon the intrinsic elasticity of the cardboard blank which is achieved if the folding lines 6 are formed as so called scribed lines and the folding lines 7 and 8 as so called crease. Also in this case, all glue surfaces lie on the "outside" of the blank, i.e. that side of the blank which shall form the outside of the trough. If the folds 14, 15 shall be forced outwards by the male part 18, and thus be pressed towards the outside of the wall part zone 16, or be forced inwards against the inside of the wall part zone 16, is decided beforehand by the trough manufacturer if this during manufacturing of the folding lines 6-8 render these a certain pre-oriented folding crease, so that the folding line 7 with certainty will move in the desired direction during the movement of the male part 18 into the female part 17.

The above mentioned type of cold seal glue may also be used for sealing the lid 21 and 22 respectively against the trough, see Fig 5 and 6. the lid 21 and 22 respectively, are for

this object provided with edge flanges 23-24 and 23 '-24' respectively, one side of which is coated with said glue. A corresponding glue coating is also present at the under side of the trough blank edge flanges 11-12. During folding of the edge flanges 23-24 and 23 '-24' respectively, of the lid, into contact with the under side of the trough edge flanges 11-12, the two said glue coatings will therefore come against each other, so that immediate adherence will occur.

There is never any risk that the glue surface at the flange under side of the lid unintentionally catches the glue surface of the under side of the trough flange, because these surfaces never get into contact with each other until the lid has been moved into position over the trough. First when the lid has been positioned and lies upon the upper side of the trough flanges, the lid flanges then are folded down under the trough flanges and are pressed against these so that ^" gluing occurs between the glue surfaces of the lid flanges and the glue surface of the appurtenant trough flange.

Because it will then be difficult for the consumer to separate the lid from the tray, it may be possible to provide the lid with a perforation, (not shown) , which makes it possible for a segment of the lid to be torn off to expose the contents of the trough.

The invention is however not limited to the above described and in the drawings shown embodiment but may be varied within the scope of the claims without departing from the scope of the invention. For example, the method may be performed with the parts turned in the opposite direction than the shown and described according to the above and also in the opposite order. In order to increase the cold seal effect, a primer of a prior art type may be supplied to the blank whereby better results may

be achieved and that tolerance towards how each work operation is performed like achieving sufficient compression.