WO2018178846A1

WO2018178846A1 - Apparatus for making plywood panels

Info

Publication number: WO2018178846A1
Application number: PCT/IB2018/052042
Authority: WO
Inventors: Giorgio LOTTERI; Lorenzo BOLZONI
Original assignee: Angelo Cremona SpA
Current assignee: Angelo Cremona SpA
Priority date: 2017-03-28
Filing date: 2018-03-26
Publication date: 2018-10-04
Anticipated expiration: 2019-09-28
Also published as: IT201700034071A1

Abstract

The present invention relates to an apparatus for making plywood panels (1) comprising: a first coating station (3) for coating a first sheet-like element (30), comprising a first coater (32) configured to coat a single face of said first sheet-like element (30) with an adhesive substance; - a second coating station (5) for coating a second sheet-like element (50), comprising a second coater (52) configured to coat a single face of said second sheet-like element (50) with an adhesive substance; - a doubling station (7) configured to stack said first sheet-like element (30) on said second sheet-like element (50) in order to form a double sheet element (70); - a composing station (9), distinct from the doubling station (7) configured to receive one or more of said double sheet elements (70) and/or to stack a plurality of said double sheet elements (70).

Description

APPARATUS FOR MAKING PLYWOOD PANELS

The present invention relates to an apparatus for making plywood panels.

Plywood panels are semi-finished products comprising multiple dry peeled sheets of wood that are glued together and hot pressed.

A part of these sheets is then coated with glue which, during the pressing step, as a result of the heat and of the pressure, reacts polymerising and hardening, thus joining together the various sheets that comprise the plywood panel.

Generally, the wood sheets can have a development of the fibres that is substantially parallel to the long side of the sheet itself, or a development of the fibres that is substantially orthogonal to the long side of the sheet itself.

In a plywood panel, the various sheets are mutually superposed and generally arranged with the fibres alternated by 90° so that the mechanical characteristics of the panel are homogeneous in all directions .

When the upper face of the panel has the fibres of the wood substantially parallel to the long side of the panel, this panel is generally defined, as a whole, as a "longitudinal panel". If the fibres of the wood of the upper face are parallel to the short side of the panel, it is defined as a "crosswise panel".

The processes for manufacturing plywood panels currently in use entail superposing a plurality of individual sheets alternating a sheet without glue to a sheet coated with glue on both its faces. In these known processes, spreading machines are used which distribute glue homogeneously, according to adjustable quantities, on both the faces of a sheet.

The manufacture of a plywood panel entails arranging a first sheet, called "back" because it will constitute the lower part of the panel, not coated with glue and then superposing, in sequence, a second sheet, called "crossband", coated with glue on both faces, and a third sheet, called "core", without any glue.

The alternating superposition of the "crossband" sheet and of the "core" sheet is repeated until the desired number of layers is reached. The last sheet applied, called "face" is always a sheet without any glue, and it is the one that closes the composition sequence of the plywood panel.

The number of sheets, like the thickness of each sheet, is variable according to the thickness of the plywood panel to be manufactured.

However, the number of sheets that are used is always odd because the first sheet of veneer lacks glue, the second one will have glue on both faces, the third one will have no glue, the fourth one will have glue above and below, while the last one will be without glue.

With this method, therefore, it is possible to compose only plywood panels with a number of sheets that is odd and greater than or equal to three.

The apparatuses that carry out these operations are called plywood making machines and they comprise a spreader machine that spreads glue on the opposite faces of the "crossband" sheets and conveyor belts that convey the "crossband" sheets, the "back", "core" and "face" sheets in suitable stations where the various sheets are picked up and superposed in sequence, as described previously.

Personnel assigned to these apparatuses can be in a variable number, generally between three and eight, depending on the operations they have to perform and the degree of automation provided by the apparatus.

These known apparatuses are not free of drawbacks, including the fact that they often require a high number of operators.

Another drawback of these known apparatuses consists of the fact that the number of sheets that can be assembled to obtain the plywood is always odd and always greater than or equal to three.

An additional drawback of these known apparatuses consists of the fact that they require continuous, costly cleaning cycles because of the glue that is deposited, often in an uncontrolled manner, on various parts of the apparatus. In particular, the "crossband" sheets, which have both their faces coated with glue, release, when being transported, glue residues on the belt conveyors and on the various devices that actuate them.

The main purpose of the present invention is to provide an apparatus for making plywood panels that overcomes the limits of the prior art.

Another purpose of the present invention is to provide an apparatus for making plywood panels that allows to make different types of plywood panels, without limitations on the number of usable sheets and without limitations on the succession of the related layers to be superposed. A further purpose of the present invention is to provide an apparatus for making plywood panels that requires minimal intervention on the operators' part.

Yet another purpose of the present invention is to provide an apparatus for making plywood panels that assures high cleanliness standards.

An additional purpose of the present invention is to provide a particularly simple and functional apparatus, with low costs.

Another purpose of the invention is to provide an apparatus that is able to give the amplest assurance of reliability and safety in use.

These purposes according to the present invention are achieved obtaining an apparatus for making plywood panels as set forth in claim 1.

Further features are provided in the dependent claims .

Other features and advantages will be more readily apparent from the description of a preferred, but not exclusive embodiment of an apparatus for making plywood panels, illustrated by way of non-limiting indication with the aid of the accompanying drawings in which:

figure 1 is a plan top view of an embodiment of an apparatus for making plywood panels, according to the invention;

figures 2, 3 and 4 are side elevation views of the doubling station of the apparatus of figure 1, according to the invention, illustrated in three successive utilisation steps;

figures 2a, 3a and 4a illustrate enlarged details respectively of figures 2, 3 and 4;

figures 5, 6, 7 and 8 are front elevation views of the composing station of the apparatus of figure 1, according to the invention, illustrated in four successive utilisation steps;

figures 9 to 14 schematically show six different examples of plywood panels that can be made with the apparatus according to the invention.

With reference to the aforementioned figures, the apparatus for making plywood panels, indicated globally with the reference numeral 1, comprises:

- a first coating station 3 for coating a first sheetlike element 30, comprising a first coater 32 configured to coat a single face of the first sheet^¬ like element 30 with an adhesive substance;

a second coating station 5 for coating a second sheet-like element 50, comprising a second coater 52 configured to coat a single face of the second sheet^¬ like element 50 with an adhesive substance;

- a doubling station 7 configured to stack said first sheet-like element 30 on the second sheet-like element 50 in order to form a double sheet element 70;

a composing station 9, distinct from the doubling station 7, configured to receive one or more of said double sheet elements 70 and/or to stack a plurality of said double sheet elements 70.

Advantageously, the composing station 9 is configured to receive double sheet elements 70 exiting the doubling station 7 and therefore to operate on said double sheet elements 70.

Advantageously, moreover, the operation of forming the double sheet element 70 in the doubling station 7 can be carried out concurrently with the operations of receiving one or more double sheet elements 70 and/or of stacking a plurality of double sheet elements 70.

Advantageously, the apparatus 1 also comprises a station for pressing and baking the double sheet elements 70 drawn from the composing station 9, not shown in the accompanying figures, in which station the plywood panel is formed.

Advantageously, the first coating station 3 comprises first pick-up means 34 for picking up the first sheet-like element 30 and a first viewing system configured to detect the position of the first sheet^¬ like element 30. Said first pick-up means 34 are adapted to align a first edge 31 of the first sheet^¬ like element 30 with respect to a first transport direction 36 based on the position of the first sheet- like element 30 detected by the first viewing system.

Advantageously, the second coating station 5 comprises second pick-up means 54 for picking up the second sheet-like element 50 and a second viewing system configured to detect the position of the second sheet-like element 50. Said second pick-up means 54 are adapted to align a first edge 51 of the second sheet^¬ like element 50 with respect to a second transport direction 56, orthogonal to the first transport direction 36, based on the position of the second sheet-like element 50 detected by the second viewing system.

The present invention also relates to a coating station 3, 5, in particular for an apparatus for making plywood panels 1, comprising:

- pick-up means 34, 54 for picking up a sheet-like element 30, 50;

- a viewing system configured to detect the position of the sheet-like element 30, 50, where the pick-up means 34, 54 are adapted to align an edge 31, 51 of the sheet-like element 30, 50 with respect to a transport direction 36, 56 of the sheet-like element 30, 50 based on the position of the sheet-like element detected by the viewing system;

- a coater 32, 52 configured to coat a single face of the sheet-like element 30, 50 with an adhesive substance .

Advantageously, the viewing system is mounted aboard the pick-up means 34, 54 for picking up the sheet-like element 30, 50. In this way the viewing system can already operate during the pick-up and the displacement of the sheet-like elements 30, 50.

Advantageously, the coater 32, 52 is configured to coat only the upper face of the sheet-like element 30, 50 with an adhesive substance.

Advantageously, the pick-up means 34, 54 for picking up the sheet-like elements 30, 50 comprise a robot arm 35, 55 provided, at its own end, with a set of suction cups 37, 57 configured to pick-up the sheet^¬ like element 30, 50.

Advantageously, the viewing system comprises a video camera fixed to the robot arm 35, 55, or a video camera situated in a fixed position with respect to the coating station 3, 5.

Advantageously, the pick-up means 34, 54 comprise an industrial robot, for example of the type of the manipulator robots and/or of the multi-axis robots.

The first coating station 3 and/or the second coating station 5 advantageously comprise at least one loading station 13 where the sheet-like elements 30, 50 are stored.

Advantageously, for each coating station 3, 5, a plurality of loading stations 13 may be present, in order to load sheet-like elements 30, 50 of different quality and/or type and in such a way as to avoid idling the plant if the pack of sheet-like elements 30, 50 present on the platform of the loading station 13 is exhausted .

Advantageously, the doubling station 7 comprises a first transport line 72 able to transport the first sheet-like element 30 and a second transport line 74 adapted to transport the second sheet-like element 50. The second transport line 74 is positioned at a greater height than the first transport line 72. To the second transport line 74 are associated support means 76 for supporting the second sheet-like element 50. The support means 76 are slidably extractable cantilevered with respect to the second transport line 74. In a fully extracted configuration, said support means 76 substantially completely surmount the first transport line 72.

Advantageously, the first transport line 72 can comprise, downstream of the first coater 32, a plurality of modular conveyors in line, indicated, in figure 1, with the reference numerals 72a and 72b.

Advantageously, said first transport line 72 continues in line with an additional modular conveyor 72c positioned upstream of the first coater 32, at the first coating station 3.

Advantageously, also the second transport line 74 can comprise a plurality of modular conveyors in line. In the embodiment of the apparatus 1 shown in figure 1, the second transport line 74 comprises a modular conveyor 75 downstream of the second coater 52, and continues in line with an additional modular conveyor 74c positioned upstream of the second coater 52, at the second coating station 5.

The first pick-up means 34 of the first coating station 3 pick-up the first sheet-like element 30 from the respective loading station 13 and place it on the conveyor 72c, upstream of the coater 32, so that its edge 31 is aligned to the first transport direction 36.

Similarly, the second pick-up means 54 of the second coating station 5 pick-up the second sheet-like element 50 from the respective loading station 13 and place it on the conveyor 74c, upstream of the coater 52, so that its edge 51 is aligned to the second transport direction 56.

Advantageously, the second transport line 74 has at least one terminal segment defined by the conveyor 75, preferably of the belt type 75. The support means 76 advantageously comprise a fork 77, for example comprising a plurality of round pipes.

When the second sheet-like element 50 reaches the end of the belt conveyor 75, the support means 76 are extracted, as shown in figure 3, synchronously with the movement of the belt conveyor 75, so that the second sheet-like element 50 lies down on the support means 76 and, in the fully extracted configuration of the support means, the second sheet-like element 50 is positioned vertically above and at the first sheet-like element 30 which in the meantime has reached, along the first transport line 72, the doubling station 7.

The doubling station 7 advantageously comprises a third viewing system, configured to detect the position of the first sheet-like element 30 and the position of the second sheet-like element 50. The first transport line 72 can be actuated to move said first sheet-like element 30 along the first transport direction 36 on the basis of the position of the second sheet-like element 50 detected by the third viewing system so that a second edge 33 of the first sheet-like element 30, orthogonal to the first edge 31, is aligned to the first edge 51 of the second sheet-like element 50.

Advantageously, the third viewing system comprises a video camera positioned substantially above the belt segment 75 of the second transport line 74 adapted to detect the position of the second sheet-like element 50, and in particular the position of its first edge 51, and a photocell positioned at the entry of the doubling station 7 at the first transport line 72, and preferably positioned at the entry of the modular conveyor 72a, adapted to detect the position of the first sheet-like element 30, and in particular of its transverse edge 33.

Advantageously, the movement of the modular conveyor 72a can be managed through a position transducer whereby the position of the first sheet-like element 30 can be managed.

When the first sheet-like element 30 and the second sheet-like element 50 are vertically aligned relative to the respective edges 33 and 51, the support means 76 return between the belts of the belt conveyor 75 and a stop rack 78 intervenes to block the second sheet-like element 50, preventing it from following the fork 77 in the return movement, making the second sheet-like element 50 fall and lie down on the first sheet-like element 30.

Advantageously, the first transport direction 36 is an imaginary work line that coincides with the stop line defined by the stop rack 78. Therefore, in the first coating station 3, the first sheet-like element 30 is picked up by the robot arm 35 and deposited on the modular conveyor 72c already with its own longitudinal edge 31 coinciding with the aforesaid imaginary work line, as a result of the feedback provided by the video camera present in the coating station 3.

Advantageously, the second transport direction 56 is an imaginary work line that is selected a priori according to the dimensions of the sheet-like elements 30, 50. In particular, in the second coating station 5, the video camera detects the position of the second sheet-like element 50 and the robot arm 55 positions it on the conveyor 74c so that its transverse edge 51 coincides with said imaginary work line.

In this way, in the doubling station 7, all the edges of the two sheet-like elements 30 and 50 are aligned to the transport directions 36 and 56 and hence mutually aligned. Therefore, the long sides and the short sides of the two sheet-like elements 30 and 50 coincide with each other. The two sheet-like elements 30 and 50 thus stacked and doubled define the double sheet element 70.

Advantageously, the composing station 9 comprises a third transport line 92 adapted to transport the double sheet element 70. The third transport line 92 is positioned at a greater height than a resting plane 94 for the double sheet elements 70. To the third transport line 92 are associated support means 96 for supporting the double sheet-like element 70. The support means 96 are slidably extractable cantilevered with respect to the third transport line 92. In a fully extracted configuration, the support means 96 surmount the resting plane 94.

Advantageously, also the third transport line 92 can comprise a plurality of modular conveyors 92a in line.

In this case, too, the movement of extraction of the support means 96 can be synchronised with the transport movement of the third transport line 92 so that the double sheet element 70 is laid on said support means 96 until the completely extracted configuration of the support means 96. In this configuration the double sheet element 70 is positioned vertically above the resting plane 94 where other double sheet elements 70 may already be positioned, having previously reached the composing station 9.

During the return of the support means 96, the double sheet element 70 can be held by one or more operators, which prevent the double sheet element 70 from following the support means 96 in their return motion and allow to lay the double sheet element 70 on the resting plane 94, or on other double sheet elements 70 already present on the resting plane 94.

Alternatively, the double sheet element 70 can be held in position, during the return motion of the support means 96, by a stop rack like the one described and illustrated with reference to the doubling station 7. The support means 96 can comprise an extractable fork like the one described with reference to the doubling station 7, or like an extractable table.

The apparatus 1 advantageously comprises a finishing station 11 configured to stack a sheet-like finishing element 110 on the double sheet element 70, or on the double sheet elements 70, that exit from the composing station 9.

The sheet-like finishing element 110 can be a sheet-like element of the type of the first sheet-like element 30 or of the type of the second sheet-like element 50, or a sheet-like element having particular aesthetic and qualitative features.

Advantageously, the finishing station 11 can comprise pick-up means 111 for picking up the sheet^¬ like finishing element 110, preferably comprising a robot arm 112 and a set of suction cups 113, and a viewing system configured to align the sheet-like finishing element 110 with respect to the double sheet element 70.

Advantageous, the pick-up means 111 comprise an industrial robot, for example of the type of the manipulator robots and/or of the multi-axis robots.

Advantageously, the first transport line 72, and/or the third transport line 92, can comprise at least a conveyor belt at least partially provided with a plurality of holes and a suction system adapted to ensure that the first sheet-like element 30 and/or the double sheet element 70 adhere to said conveyor belt.

Advantageously, also the second transport line 74 can comprise at least a conveyor belt at least partially provided with a plurality of holes and a suction system adapted to ensure that the second sheet^¬ like element 50 adheres to said conveyor belt.

Advantageously, the first sheet-like element 30 is a sheet having fibres extending lengthwise and the second sheet-like element 50 is a sheet having fibres extending cross-wise.

Advantageously, the first coater 32 and/or the second coater 52 comprise at least a coating roller configured to apply a homogeneous layer of the adhesive substance only on the top surface of the first sheet^¬ like element 30 and/or of the second sheet-like element 50.

Advantageously, the at least one coating roller has a rotation axis substantially orthogonal to the extension direction of the fibres of the first sheet^¬ like element 30 and/or of the second sheet-like element 50.

Advantageously, the coaters 32, 52 are configured to apply a quantity of adhesive substance substantially in the range between 70 and 300 grams per square metre.

Advantageously, the coaters 32, 52 are adapted to apply different types of adhesive substances, such as glues of the urea or phenol type, on sheet-like elements of different formats.

The operation of the apparatus 1 for making plywood panels is described below.

In the case of the production of a so-called "longitudinal" plywood panel, i.e. a panel that has an upper face defined by a sheet-like element with longitudinal fibres like the one shown schematically in figure 9, the production cycle is as follows.

A first sheet-like element 30, with fibres extending lengthwise, is picked up from the platform of the loading station 13, deposited on the conveyor 72c and made to pass through the coater 32, which applies a layer of adhesive substance only on the upper face of the sheet-like element 30.

Thanks to the pick-up means 34 and to the viewing system, the sheet-like element 30 has its own longitudinal edge 31 aligned with the longitudinal transport direction 36.

Said sheet-like element 30 will constitute the back of the plywood panel.

The presence of the suction system assures that the sheet-like element 30 remains adhering to the upper surface of the modular conveyors 72a, 72b and 72c, and hence maintains alignment to the longitudinal transport direction 36.

The sheet-like element 30 that reaches the doubling station 7 therefore only has its upper face coated with an adhesive substance, while the lower face is dry.

In the meantime, the second sheet-like element 50, with fibres extending crosswise, is picked up by the pick-up means 54 and deposited on the conveyor 74c with its own transverse edge 51 aligned to the orthogonal transport direction 56.

The longitudinal transport direction 36 and the orthogonal transport direction 56 intersect at the doubling station 7 where they define a right angle that represents the reference for the stacking of the sheet^¬ like elements 30, 50 that constitute the double sheet element 70.

The second sheet-like element 50 passes through the second coater 52, where a layer of adhesive substance is applied only on the upper face of the sheet-like element 50.

When the second sheet-like element 50 reaches the terminal belt segment 75 of the second transport line 74, the support means 76 exit cantilevered, synchronously with the movement of the second sheet^¬ like element 50. The second sheet-like element 50 is laid down on said support means 76, and it is positioned above and at the first sheet-like element 30 that has already reached the doubling station 7.

The first transport line 72, and in particular the conveyor 72a, is then made to advance and/or move back according to the position of the first sheet-like element 30 with respect to the orthogonal transport direction 56 until the transverse edge 33 of the first sheet-like element 30 is aligned vertically with the transverse edge 51 of the second sheet-like element 50.

In this case, the video camera of the third viewing system detects the position of the transverse edge 51 of the second sheet-like element 50 on the forks 77 and the modular conveyor 72a will be moved forwards and backwards, by means of a position transducer, to align the transverse edge 33 of the first sheet-like element 30 with the transverse edge 51 of the second sheet-like element 50, on the basis of the position of the transverse edge 33 of the first sheet-like element 30 detected by the photocell positioned at the entry of the belt 72a.

At this point the support means 76 are made to return, while the stop rack 78 holds the second sheet^¬ like element 50 in position. In this way the second sheet-like element 50 falls, lying with its dry lower face on the upper face, coated with glue, of the first sheet-like element 30, thus making the double sheet element 70.

Through the third transport line 92, the double sheet element 70 is carried to the composing station 9.

As soon as the double sheet element 70 arrives with the front edge on the end of the transport line 92, the support means 96 project cantilevered to receive the double sheet element 70. The holding of the double sheet element 70, manually by assigned operators, or mechanically by a stop rack, allows the double sheet element 70 to fall and be laid down on the resting plane 94.

The steps described above are repeated a number of times equal to the double sheet elements 70 that will comprise the plywood panel.

Advantageously, the resting plane 94 can be defined by and/or comprise an additional conveyor 95 which, once the various double sheet elements 70 are stacked, carries said composition of stacked double sheet elements 70 to the finishing station 11. Here, a sheet^¬ like finishing element 110, which will constitute the visible face of the plywood panel, is applied superiorly to the composition of double sheet elements 70.

Advantageously, the finishing station 11 comprises a conveyor 97, in line with the conveyor 95, adapted to move the composition of double sheet elements 70 before and/or after the sheet-like finishing element 110 is applied.

The coupling of the sheet-like finishing element 110 with the composition of double sheet elements 70 takes place on the conveyor 97 where a video camera detects the forward edge of the composition of double sheet elements 70. The robot arm 112 then positions the sheet-like finishing element 110 on the composition of double sheet elements 70, so that the respective edges are aligned.

When all the elements composing the plywood panel are assembled, they are transferred, for example by means of the conveyor 97, to the pressing and baking station where the plywood panel is completed.

The example of operation of the apparatus 1 described above allows to obtain a plywood panel as shown schematically in figure 9, i.e. a so-called "longitudinal" panel comprising a plurality of double sheet elements 70 defined by pairs of longitudinal 30 and crosswise 50 sheet-like elements and a sheet-like finishing element 110, which can have a different appearance and quality from the other sheet-like elements 30, 50.

To make a so-called "crosswise" panel, like the one shown in figure 10, a crosswise sheet-like element 50, coated with glue on its upper surface by the coater 52, is carried to the composing station 9 without being preliminarily coupled with longitudinal sheet-like elements 30. On said crosswise sheet-like element 50 is then stacked a double sheet element 70, and hence a longitudinal sheet-like element 30 not associated with any crosswise sheet-like element 50. The panel is then finished with the application of the sheet-like finishing element 110.

As shown in figures 11 and 12, it is possible to make both longitudinal and crosswise plywood panels with an even number of sheet-like elements 30 and 50.

Moreover, the apparatus 1, activating only one of the two coating stations 30, 50, also allows to make plywood panels consisting only of crosswise sheet-like elements 50, as shown in figure 13, or consisting only of longitudinal sheet-like elements 30, as shown in figure 14.

The apparatus 1 also allows to make plywood panels consisting of only two sheet-like elements and, specifically, of a longitudinal or crosswise sheet-like element and of a sheet-like finishing element.

In practice, it has been observed that the apparatus for making plywood panels, according to the present invention, performs its task and achieves the set purposes because it allows to make plywood panels without any limitations on the number and on the type of wood sheets usable to make the panel.

In particular, it is possible to make plywood panels defined by only two wood sheets.

Moreover, not having any limitations on the number of sheets to be used, it is easier to obtain panels of different thicknesses, using different combinations, types and thicknesses of sheets, optimising the utilisation of the material and thus saving on costs.

Moreover, the apparatus for making plywood panels of the present invention has the advantage of assuring a perfect stacking and a perfect gluing of the wood sheets .

Yet another advantage of the apparatus, according to the invention, consists of the fact that the coating of only the upper face of the sheets avoids fouling the transport systems and therefore avoids costly cleaning cycles of the apparatus itself.

Another advantage of the apparatus, according to the invention, consists of the fact that it assures a significant automation of the steps for making the plywood panels, consequently reducing the number of operators assigned and the costs of the personnel.

An additional advantage of the apparatus, according to the invention, consists of the fact that it is not subject to frequent idle times of the plant because of the exhaustion of the sheets, because the sheets can be picked up from various loading stations positioned at the coating stations.

Yet another advantage relates to the fact that the apparatus according to the invention allows to halve the time required to make the plywood panels, as a result of the fact that the operations for forming the double sheet element, carried out in the doubling station, can be carried out simultaneously with the operations for stacking the various double sheet elements, carried out in the distinct composing station .

Still another advantage, with particular reference to the coating station, relates to the fact that said coating station is in itself autonomous and complete and as such easy to integrate in a multi-station apparatus for the composition of plywood panels like the one of the present invention.

The apparatus for making plywood panels thus conceived is susceptible to numerous modifications and variants, without departing from the scope of the invention; moreover, all details can be replaced with other technically equivalent elements. In practice, the materials used, as well as their dimensions, can any type according to the technical requirements.

Claims

1) Apparatus for making plywood panels (1) comprising :

a first coating station (3) for coating a first sheet-like element (30), comprising a first coater (32) configured to coat a single face of said first sheet^¬ like element (30) with an adhesive substance;

- a second coating station (5) for coating a second sheet-like element (50), comprising a second coater (52) configured to coat a single face of said second sheet-like element (50) with an adhesive substance;

- a doubling station (7) configured to stack said first sheet-like element (30) on said second sheet-like element (50) in order to form a double sheet element (70);

- a composing station (9), distinct from said doubling station (7), configured to receive one or more of said double sheet elements (70) and/or to stack a plurality of said double sheet elements (70) .

2) Apparatus according to claim 1 characterized in that said first coating station (3) comprises:

first pick-up means for picking up (34) said first sheet-like element (30);

- a first viewing system configured to detect the position of said first sheet-like element (30);

said first pick-up means (34) being adapted to align a first edge of said first sheet-like element (30) with respect to a first transport direction (36) based on said position detected by said first viewing system.

3) Apparatus according to claim 1 or 2, characterized in that said second coating station (5) comprises :

- second pick-up means for picking up (54) said second sheet-like element (50);

- a second viewing system configured to detect the position of said second sheet-like element (50);

said second pick-up means (54) being adapted to align a first edge of said second sheet-like element (50) with respect to a second transport direction (56), orthogonal to said first transport direction (36), based on said position detected by said second viewing system.

4) Apparatus according to one or more of the preceding claims, characterized in that said doubling station (7) comprises a first transport line (72) adapted to transport said first sheet-like element (30) and a second transport line (74) adapted to transport said second sheet-like element (50), said second transport line (74) being placed at a height which is higher than said first transport line (72), support means (76) for supporting said second sheet-like element (50) being associated with said second transport line (74), said support means (76) being slidably extractable cantilevered with respect to said second transport line (74), said support means (76) being on top of said first transport line (72) in a full extracted configuration.

5) Apparatus according to one or more of the preceding claims, characterized in that said doubling station (7) comprises a third viewing system configured to detect the position of said first sheet-like element (30) and the position of said second sheet-like element (50), said first transport line (72) being actuatable to move said first sheet-like element (30) along said first transport direction (36) based on said position of said second sheet-like element (50) detected by said third viewing system so that a second edge of said first sheet-like element (30), orthogonal to said first edge of said first sheet-like element (30), is aligned to said first edge of said second sheet-like element (50) .

6) Apparatus according to one or more of the preceding claims, characterized in that said composing station (9) comprises a third transport line (92) adapted to transport said double sheet element (70), said third transport line (92) being placed at a height which is higher than a resting plane (94) for said double sheet elements (70), support means (96) for supporting said double sheet element (70) being associated with said third transport line (92), said support means (96) being slidably extractable cantilevered with respect to said third transport line (92), said support means (96) being on top of said resting plane (94) in a full extracted configuration.

7) Apparatus according to one or more of the preceding claims, characterized in that it comprises a finishing station (11) configured to stack a sheet-like finishing element (110) on said double sheet element (70) .

8) Apparatus according to one or more of the preceding claims, characterized in that said first transport line (72) and/or said third transport line (92) comprise a conveyor belt provided with a plurality of holes and a suction system adapted to ensure that said first sheet-like element (30) and/or said double sheet element (70) adhere to said conveyor belt.

9) Apparatus according to one or more of the preceding claims, characterized in that said first coating station (3) and/or said second coating station (5) comprise at least a loading station (13) where said sheet-like elements (30, 50) are stored.

10) Apparatus according to one or more of the preceding claims, characterized in that said first sheet-like element (30) is a sheet having fibres extending lengthwise and that said second sheet-like element (50) is a sheet having fibres extending cross^¬ wise.

11) Apparatus according to one or more of the preceding claims, characterized in that said first coater (32) and/or said second coater (52) comprise at least a coating roller configured to apply a homogeneous layer of said adhesive substance only on the top surface of said first sheet-like element (30) and/or said second sheet-like element (50), said at least one coating roller having a rotation axis substantially orthogonal to the extension direction of the fibres of said first sheet-like element (30) and/or of said second sheet-like element (50) .

12) Apparatus according to one or more of the preceding claims, characterised in that said viewing system is mounted aboard said pick-up means (34, 54) for picking up said sheet-like element (30, 50) .

13) Coating station (3, 5), in particular for an apparatus for making plywood panels (1), comprising:

- pick-up means for picking up (34, 54) a sheet^¬ like element (30, 50);

a viewing system configured to detect the position of said sheet-like element (30, 50), said pick-up means (34, 54) being adapted to align an edge of said sheet-like element (30, 50) with respect to a transport direction (36, 56) of said sheet-like element (30, 50) based on said position detected by said viewing system;

- a coater (32, 52) configured to coat a single face of said sheet-like element (30, 50) with an adhesive substance.

14) Coating station (3, 5), according to claim 13, characterised in that said viewing system is mounted aboard said pick-up means (34, 54) for picking up said sheet-like element (30, 50) .