This invention relates to a method of providing an oblong plant trough with end walls, the plant trough having an essentially flat bottom and two parallel lengthwise side walls extending from the bottom, and the lengthwise edges of said side walls, as seen in cross section, having been doublefolded along a predetermined distance, and the plant trough being made of metal.

Plant troughs are commonly used in greenhouses for the cultivation of plants, and in the plant troughs the plants may be transported, rearranged or otherwise handled as needed for optimal care of the plants.

A plant trough of this description is oblong and has an essentially U-shaped cross section comprising a bottom and two essentially parallel lengthwise side walls-, in addition to which the plant trough may be closed tightly at each end with an end wall if required in consideration of the necessary irrigation method for the cultivation of one or more plant species. In other cases it will be more appropriate to use plant troughs without end walls.

A plant trough may be made from moulded material or it may be a metal plate bent into the U-shaped cross section men¬ tioned.

According to its use, a plant trough must be produced in various lengths, which may be 8 - 12 meters, depending upon the plant table, upon which the plant trough is to be placed, for which reason a plant trough made from moulded material and with end walls is costly to produce in its finished length with integrated end walls, since each length will require a separate tool. For the same reason, a plant trough made from metal is equally costly

to provide with the end walls as integral parts of the plant trough.

In consequence hereof, it is common procedure to produce separate end walls, for example by moulding them from plastic and glue the end walls thus produced into the hollow of a U-shaped profile for a plant trough cut into the desired length.

It is, however, a costly procedure to make a plant trough of arbitrary length with end walls, which are initially made separately and subsequently glued onto or otherwise attached tightly to a U-shaped profile for a plant trough. The costs of placing an end wall is app. DKK 12,- each (beginning 1987) plus mounting costs and glue. In the course of time glued end walls of this kind will result in leaks because of differences in materials and temperature increase coefficients as well as deterioration ^• of glue and plastic.

It is an object of this invention to describe a method of providing a plant trough of arbitrary length with end walls in such a manner that this process can be performed at a far lower price than known up to now.

This will be achieved by a procedure according to this in¬ vention, which procedure is characteristic in that in the first stage the first end of the plant trough is formed by removing from the side walls at the mentioned first end the outermost section corresponding to the distance men¬ tioned, in that a corresponding section is removed along the lengthwise edge of the side walls, in that the outer¬ most part of the bottom is folded in consecutive steps in the direction indicated by the side walls along a line, which, reckoned from the said first end of the plant trough, extends at right angles to the longitudinal di¬ rection of the plant trough and across the bottom in a

distance exceeding the height of the side walls, to produce an end wall extending from the bottom, in that parallel herewith the two essentially equilateral trian¬ gular corners are folded, said corners being defined in part by the line mentioned and in part by lines in conti¬ nuation of the edges of the two side walls along the bottom, in such a manner that the diagonal extending from the free corners of the triangular corners are folded either upwards in the direction mentioned or downwards in the opposite direction, in that the consecutive folding steps of the triangles produced by the triangular corners are turned to rest against the inside respectively the outside of the end wall formed, in that the section cor¬ responding to the mentioned predetermined distance is folded towards, respectively away from the hollow of the plant trough and again to rest against the inside respec¬ tively the outside of the end wall formed by the folding steps and the part of the triangles located farthest away from the bottom, and in that a corresponding end wall at the opposite end of the plant trough is formed subsequent¬ ly-

A plant tray of arbitrary, predetermined length is thus produced in an inexpensive way, the procedure being con- siderably cheaper than in the prior art, where separately produced end walls have been placed and attached by glue¬ ing them into a U-shaped profile for a plant trough. The end wall produced according to this invention is comple¬ tely tight and remains tight during the entire lifetime of the plant trough, and due to the folding procedure sharp edges are avoided, which could cause danger to employees in a nursery or during handling otherwise of a plant trough.

For the production of an end wall in a plant trough as de¬ scribed above it may be preferable, as described in Claim 2, to form the end wall in a plant trough in a maximum of

four steps, whereupon the plant trough is turned 180° a- round an axis placed at right angles to the bottom, where¬ upon an end wall is formed at the opposite end of the plant trough.

The division of the folding procedure into a maximum of four steps has proven advantageous, in part because ex¬ cessive metal strain is avoided as would have been the case if fewer folding steps had been implemented, and in part because the folding tools may be prepared in a simple way with linear operations only, in contrast to what would have been the case using a single tool, which would re¬ quire a far more complicated tool with movable and rota- table parts, which at different stages of the folding pro- cess should then continue the folding process of the parts for the end walls into the final position. By turning the plant trough 180° around an axis placed at right angles to the bottom before forming the end wall at the opposite end of the plant trough, it is achieved that the formation of the two ends of the trough in one tool only can be done mechanically, the turning being performed in an automatic process.

The invention also relates to an apparatus for the imple- mentation of the method described, which apparatus is cha¬ racteristic in that it has cutting means for the removal of a predetermined section from the outermost part of the side walls at a first end of a plant trough, in that the apparatus has a first set of folding devices prepared in consecutive steps to fold the outermost part of the bottom at the mentioned first end in the direction defined by the side walls along a line, which, reckoned from the mentioned first end of the plant trough, extends at right angles to the longitudinal direction of the plant trough and across the bottom at a distance exceeding the height of the side walls to produce an essentially upright end wall at right angles to the bottom, in that the apparatus

has a second set of folding devices prepared, con¬ currently with the steps performed by the first set of folding devices, to fold the two essentially equilateral triangular corners defined in part by the mentioned line and in part by lines in continuation of the two edges a- long the bottom of the side walls in such a manner that the diagonal of the free corners of the triangular corners is folded either upwards in the direction mentioned or downwards in the opposite direction and to turn the tri- angles produced by the folding of the triangular corners to rest against the inside respectively the outside of the upright end wall, and in that the apparatus has a third set of folding devices prepared to fold the section of the end wall corresponding to the predetermined length towards respectively away from the hollow of the plant trough and again to rest against the inside respectively the outside of the end wall produced by the folding steps and the part of the triangles farthermost away from the bottom.

It has proven advantageous, as described in Claim 4, that the apparatus comprises a maximum of four tools placed next to each other, further that the first tool comprises the cutting means mentioned and the said first and second set of folding devices prepared to carry out an initial folding of the end of the plant trough, and that the last tool comprises the last set of folding devi¬ ces, and that between the first and the last tool further tools comprising folding devices have been placed, pre¬ pared to perform intermittent folding operations of the said outermost part of the bottom and of the triangular corners, in addition to which the apparatus comprises transport devices prepared to carry an end of a plant trough intermittently through the tools mentioned, as well as means to turn at least one plant trough at a time 180° around an axis placed at right angles to the bottom of the trough and to lead the opposite second end of the plant trough through the apparatus.

In addition, it has proven advantageous as described in Claim 5 that the transport devices consist of a sliding device on a guide bar provided with retaining devices to hold a plant trough with one of its ends in place in a position which can be actuated by one of the tools, in addition to which the apparatus has steering devices to move the sliding device intermittently in a working circle with the tools.

Furthermore, it has proven advantageous as described in Claim 6 that the maximum of four tools have been prepared to be actuated hydraulically, either separately or collec¬ tively, and that a steering mechanism has been provided to intermittently move the mentioned transport devices for a plant trough through the apparatus depending upon the influences of the mentioned tools from one tool to the next.

The procedure and the apparatus according to the invention are described in detail with reference to the drawings, in which

Fig. 1 illustrates a finished plant trough with end walls according to the invention, in which the triangles produced by folding have been folded to rest against the inside of the end wall.

Fig. 2 illustrates a horizontal plan of a metal plate formed at one end,

Fig. 3 illustrates the first end of the formed metal plate after the first folding,

Fig. 4 illustrates the final form of the first end after subsequent foldings,

Fig. 5 illustrates a plant trough with the finished first end and the other end being initially folded with the triangular corners folded to¬ wards the inside,

Fig. 6 illustrates an apparatus according to the inven¬ tion as seen in perspective from a first angle, and

Fig. 7 illustrates the apparatus as shown in fig. 6 as seen from another angle.

The following is a description of the method and the appa¬ ratus according to the invention explained by a plant trough, in* which the end walls are of equal height to the longitudinal side walls of a plant trough. It will be ap¬ parent for a person skilled in the art that it is within the scope of the invention to provide a plant trough fitted with end walls which are lower than the side walls, as the end walls for example could be made half the height of the side walls.

Fig. 1 illustrates an oblong plant trough 1 made of me¬ tal, which has an essentially flat bottom 2 and from the bottom 2 two upright longitudinal side walls 3, the plant trough 1 having an essentially U-shaped cross section with adequate divergence for stacking several plant troughs on top of each other, in which the longitudinal edges of the side walls 3 are double along the edge, the free edge of the side walls having been folded to overlap a along a predetermined distance 4. Hereby the free edge 5 of the side walls 3 have been formed with a soft transition and without sharp edges which might cause harm to a user of the plant trough 1.

Plant troughs 1 of this description are used in green¬ houses to contain cultivation matter or pots with cultiva-

tion matter and plants to be cultivated placed in said pots.

Plant troughs 1 are available in an infinite number of lengths depending upon the space available in the green¬ houses and upon the plants to be placed in the plant troughs 1.

Plant troughs for the cultivation of certain plant species, which, at least occasionally, should be soaked in water must necessarily be tight in order to lead water to the cultivation matter for the plants to soak up the moisture necessary for their growth. Until now, to make allowance for the need for plant troughs of individual lengths, end walls have been inserted into essentially U- shaped oblong plant troughs, which have been made in the desired length, and the end walls have been produced sepa¬ rately, for example of plastic, and subsequently secured tightly by adhesives.

In plant trough 1 both end walls 6 have been produced in the procedure according to this invention.

The end walls 6 have such an angle as compared to the bottom 2 as to make stacking of plant troughs possible and along their free edge 7 has been provided with a fold 4 similar to the fold 4 along the free edge 5 of the side walls 3.

The plant trough 1 is hereby along its entire free edge 5,7 provided with a rounded transition everywhere so that there is negligible risk of harm to the employees handling the plant trough 1, and at the same time an inexpensive plant trough 1 has been produced, which is tight and remains tight throughout its entire lifetime and can be produced in every length desirable.

Occasionally, plant troughs 1 are used for the cultivation of plants, in which water in the plant trough is to be drained away from the plant trough so that only the moisture absorbed into the cultivation matter will be at disposal of the plants. It is therefore known art to pro¬ vide plant troughs 1 with an opening or perhaps several openings 8 in the bottom 2, which may be closed with a plug, either of plastic or corresponding appropriate ma¬ terial. The opening or the openings 8 may be of arbitrary shape like the square shape illustrated in the drawing or they may be drilled holes and according to purpose may be located in the middle of the cross section of the plant trough, on the side of the cross section or possibly even on one of the side wall.

The initial subject for the plant trough 1 is formed by the procedure according to the invention in a number of steps.

The outermost section b of the side walls 3 is removed from an arbitrary end, in the following referred to as a first end, of an initial subject cut off into the de¬ sired length, the section b being of equal dimension, as seen from the longitudinal direction of the plant trough, as the fold 4 extending away from the free edge 5 of the side walls 3. A corresponding section c along the end of the longitudinal edge 4 of the side walls 3 is removed.

The sections b and c are illustrated in fig. 2.

The formation of the sections b and c can be used if the side walls and the end walls are, or supposed to be, es¬ sentially at right angles to the bottom. If these walls are not at right angles to the bottom but tilted slightly outwards, for example 8-10°, in order that several plant troughs may be stacked on top of each other, the sections b and c may deviate from this form described as an examp-

le ,

Subsequently, a folding is initiated of the end wall 6 a- long a line 1 extending at right angles to the longitudi- nal direction of the initial subject in a distance d from the mentioned first end, said distance d being equal to the mentioned fold a of the side walls 3 plus the height h of the side walls 3, that is d = a + h, in addition to which the end wall 6 is folded away from the plane de- fined by the bottom in the direction towards which the side walls 3 point.

Upon removal of the sections a and b two equilateral tri¬ angular corners 9 have been formed at the two corners of the initial subject, defined in part by the mentioned line 1 and in part by the lines s, which are an extension of the edges 10 along the bottom 2 of the two side walls 3.

The triangular corners 9 are parted by the diagonals 12 each reaching from the free corner 11 into the points of intersection 13 between the mentioned lines s and 1.

Parallel to the folding of the end wall 6 the triangular corners 9 are folded in such a manner that the diagonals 12 are folded away from the plane defined by the bottom 2 and in the same direction as the end wall 6 and the side walls 3.

By folding the end wall 6 and triangular corners 9 again triangles 14 will emerge gradually in each corner of the plant trough 1, said triangles consisting of two layers, which are linked together along the diagonals 12, said two triangles 14 as the end wall 6 has been folded to such an extent along the line 1 that the end wall 6 and the side walls 3 are essentially at right angles to the bottom 2, are folded to rest against the inside of the end wall 6.

At this point there will be a section 15 along the end wall 6 which stands out over the lengthwise edges 5 of the side walls 3 in a distance corresponding to the folded section a along the side edges 4.

This section 15 is finally turned in the direction of the hollow of the plant trough 1 and folded further until the section 15 rests against the top edge of the end wall 6 and the triangles 14, whereupon the mentioned first end of the plant trough 1 has been completed.

Subsequently the opposite side of the plant trough is formed in a corresponding way after the plant trough 1 has been turned 180° around an axis, which is at right angles to the plane of the bottom 2.

For the implementation of the procedure according to the invention the apparatus 20 shown in fig. 6 has been provi¬ ded.

The apparatus 20 comprises a framework 21 prepared to ab¬ sorb the power exerted on a plant trough 1 for the imple¬ mentation of the method. A frame 22 has been placed in the framework 21, and in the working position of the ap- paratus, an essentially horizontal bed 23 connected to the frame 22.

In the frame 22 a number of preferably four tools 24, 25, 26 and 27 have been placed in sequence.

The first tool 24 comprises cutting means to remove the mentioned sections a and b from one end of the initial subject to a plant trough 1, as well as a first and a se¬ cond set of folding devices for an initial folding of the end wall 6 and the triangular corners 9 as described above.

The fourth tool 27 comprises a last set of folding devices prepared to fold the section 15 at the end wall 6 to¬ wards the hollow of the plant trough 1 and again to rest against the top part of the side walls 6 and the triangles 14.

The second and the third tool 25, 26 comprise further folding devices prepared to perform foldings to be carried out between the initial folding in the first tool 24 and the final foldings in the fourth tool of the end wall 6 of a plant trough 1.

The four tools 24 - 27 are preferably driven by hydraulic cylinders 28, 29, 30 and 31, the compression means being supplied to the cylinders 28 - 31 through tubes 32, 33, 34 and 35, which again supplied from an unspecified compression source.

A sliding device 37 has been placed on a guide bar 36 on the bed 23, said sliding device having been prepared to slide intermittently along the four tools 24 - 27 placed in sequence by means of a compression cylinder 38.

The sliding device 37 has been provided with retaining de- vices 39 prepared to secure one end of an initial subject for a plant trough 1 in such a manner that the mentioned end will reach into the working area of the four tools 24 - 27, as the length of the initial subject must necessari¬ ly exceed a predetermined minimal length of a plant trough 1.

The intermittent sliding is adjusted by means of steering mechanisms, which are not illustrated in detail, in order that the mentioned end of the initial subject is prepared successively in the four tools 24 - 27.

After the completion of the first end of the initial sub-

ject in the four tools by the formation of an end wall 6, the initial subject is removed from one side of the ap¬ paratus 20 and transferred to a table, which is not il¬ lustrated on the drawing, where the initial subject can be turned 180° around an axis at right angles to the bottom 2, whereupon the opposite end of the initial sub¬ ject is carried through the apparatus 20.

The apparatus 20 has been prepared either to process one end of a subject intermittently as needed, as the end of the subject is led successively from one tool to the next, and the other end is subjected to the same process, each end of the subject being carried into the first tool, as the previous subject has been processed in the first tool and carried to the next and so on, whereupon a number of subjects, completed in the first end simultaneously can be turned and subsequently carried into the apparatus 20 with the opposite other end.

While the preceding refers to four tools 24 - 27 to pre¬ pare an initial subject for the formation of end walls 6 in a plant trough 1, it is not to be considered as a limi¬ tation, since the number of tools may vary depending upon the flexibility and the deep tension power of the metal preferred for the production of a plant trough 1.

In addition, it will be apparent to a person skilled in the art that although the procedure and the apparatus ac¬ cording to this invention have been explained on the basis of a plant trough, where the triangles produced by the folding have been folded to rest against the inside of the end walls, said triangles may alternatively be folded towards the outside of the end walls.