Description

Apparatus for forming stacks of panels to be fed to a user station

Technical Field

This invention relates to an apparatus for forming and moving stacks of panels, such as, for example, veneering or sheets of wood or like material, including composites, and in particular, panels whose thickness is relatively small compared to the surface area.

Background Art

Current panel sawing processes by which large panels are cut into smaller sub- panels used, for example, in the furniture industry, involve the use of apparatuses which, starting from a vertical pile of panels or sheets positioned on an elevator table:

- select (by separation) a certain number of panels from the top of the pile;

- transfer the stacks selected one after another at regular intervals to a sawing station. hi a first known example an apparatus of this kind made by the same

Applicant as this invention, panel selection is achieved by the combined operation of a stop element that references the top of the pile and a panel selection element, consisting of a pushing surface or shoulder extending vertically (that is to say, parallel with the extension of the pile). Both these elements are mounted on a crossbar that moves to and fro above the pile of panels in a direction parallel to itself between a position in which it receives the pile of panels and a position in which it feeds the panels to the sawing station.

The selection element operates in a development plane below the reference stop at the top of the pile at a distance corresponding to the desired / selected thickness of the stack of panels.

A side wall abuts against one side (end) of the pile at the face opposite the face of it nearest the selection element. Opposing the reaction exerted by the side wall, the selection element is actuated in such a way as to push a certain number of panels belonging to the pile (the number equivalent to the stack to be fed and also defined by the height of the pushing surface) below which there remain the rest of the panels of the pile which will form the subsequent stacks.

Thus, the panel selection element is equipped with a shoulder forming an opposing and pushing element designed to allow the selected stack to be fed towards a receiving zone or the user station when the crossbar begins moving forward. The crossbar is then moved horizontally in such a way as to carry the stack of panels thus selected towards the sawing station.

Said type of apparatus has proved highly satisfactory when working with relatively thick panels, that is to say, panels whose flexural rigidity is sufficiently high to allow the panels to slide, skimming over the panels below substantially lying flat and without unwanted movements.

When the panels to be selected and moved are thin, that is to say, when the surface area of the panels is very large compared to their thickness, the apparatus described above is modified and includes a wedge-shaped element forming the panel selection element which, thanks to its penetration in the pile and, helped by a simultaneous lowering of the pile performed by moving the elevator table, forms the stack by means of a gap separating it from the rest of the pile below.

Again, the wedge-shaped panel selection element is equipped with a shoulder designed to form an opposing and pushing element, allowing the selected stack to be fed towards a receiving zone when the crossbar moves. However, said type of system may have several disadvantages: once the wedge-shaped element has selected the panels which will form the stack and lifted them off the rest of the pile, the parts of the panel at the sides of the selection element may bend under their own weight on account of their flexibility and be fed unevenly. When the crossbar starts moving, the panel (or panels) tends to move out of

alignment with respect to the rest of the stack, causing moving parts to jam. When this happens, the apparatus has to be brought to an immediate stop and the panels or, even worse, the apparatus itself, may be seriously damaged.

To solve this problem, the Applicant invented and made an apparatus (see Italian patent application BO2006A000238) in which there are, again mounted on a movable crossbar, the stop element that references the top of the pile and a first wedge-shaped element which moves transversally to the pile according to the direction of panel feed, in such a way as to separate a certain number of panels from the top of the pile, thus forming a gap around the first wedge-shaped element by means of a relative movement of the pile in a vertical direction.

A second selection element (preferably wedge-shaped) is added to these elements, also being mounted on the crossbar, and able to move, respectively, in the direction of feed and relative to the crossbar along a first horizontal direction, longitudinally to the crossbar itself, allowing it to be inserted in the pile next to the first wedge-shaped element and at the gap, thus completely separating the pile at a point which is distanced from the first wedge-shaped element by sliding along the first horizontal direction. At this point the two wedge-shaped elements still form the elements for pushing the selected stack.

Said solution significantly reduced the error in the number of panels to be picked up, also increasing the certainty of feeding the panels in a straight line towards the sawing station.

However, after various studies and tests it was noticed that selecting a large number of panels, together with their flexibility, may produce a further disadvantage which is the possibility of accidentally dragging along with the selected stack the first, or the first few panels in the pile which are located immediately below the gap produced by the two wedge-shaped selection elements.

Thus, if the panels are very flexible, when the crossbar starts moving towards the sawing station, a large surface area of the stack scrapes on the top of the pile which is below the gap. Said stack scraping increases until it reaches its maximum at the part of the

stack surface furthest from the selection elements and which rests on the pile.

If the stack contains a large number of panels, that is to say, if it is very heavy, the weight of the stack bears down on the rest of the panels in the pile below and the resulting friction between the bottom of the stack being moved and the panel at the top of the remaining pile may be strong enough to drag the top panel or panels and move them out of alignment relative to the rest of the pile.

In this case, too, the apparatus has to be stopped, the damaged panels removed and normal operation resumed, with all the obvious disadvantages that this involves, especially when the apparatus forms part of a more complex production line.

Disclosure of the Invention

The aim of this invention is, therefore, to overcome the above-mentioned disadvantages by providing an apparatus capable of guaranteeing regular operation with panels of different rigidity, that is to say, even when working with highly flexible panels and panels that are selected together in stacks containing large numbers of them, making apparatus operation guaranteed and flexible.

The apparatus according to this aim is defined by the contents of the appended claims, especially claim 1, as well as any of the claims that depend, either directly or indirectly, on claim 1.

Brief Description of the Drawings

The technical features and advantages of the solution proposed by this invention are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate preferred embodiments of the invention provided merely by way of example without restricting the scope of the inventive concept, and in which:

Figure 1 is a schematic top plan view of an apparatus for forming and moving stacks of panels in accordance with the invention;

Figure 2 is a side view with some parts cut away to better illustrate others, of a detail P of the apparatus of Figure 1 ;

Figure 3 is a front view of the detail of Figure 2;

Figure 4 is a side view with some parts cut away to better illustrate others, of a detail Pl of the apparatus of Figure 1;

Figures 5 and 6 are sides views of a part of the apparatus, in particular presser elements relating to Figure 4, in two different operating conditions.

Detailed Description of the Preferred Embodiments of the Invention

With reference to Figure 1, the numeral 1 denotes in its entirety an apparatus for forming stacks 2 of panels 3 from a vertical pile 4 of panels 3 and feeding the stacks 2 to a user station.

The term panels 3 is used generically to indicate panels in the strict sense such as, for example, solid panels made of wood of various kinds and in various thicknesses but also to indicate layered veneering of composite materials such as sheets of plywood and/or like materials used for example in the furniture industry. However they are made, the panels 3 are preferably thin but very large in surface area. They are therefore highly flexible and elastically deformable even under their own weight only.

The user station is not shown in the drawings, since it is irrelevant to this invention. It might, for example, be a conventional sawing station in which the large panels 3 are cut into smaller panels according to specific application needs.

As shown in Figure 1, the apparatus 1 comprises a horizontal crossbar 5, supported at opposite ends by a pair of parallel longitudinal members 50 and actuated by respective drive means (not illustrated). The longitudinal members 50 are parallel with a horizontal feed direction A along which the panels 3 are fed towards the user station.

The crossbar 5 is mobile in a direction parallel with itself, above the pile 4 of panels 3, to and fro at least - in this embodiment - between two limits corresponding to: a position where it receives the pile 4 of panels 3, above an elevator table 11 which extends horizontally (also illustrated in Figure 2) and a

position where it places the stack 2 in the user station.

The movement of the crossbar 5 refers only to the selection position since the crossbar 5 may continue into the user station to move the selected stack 2 while it is processed. The apparatus 1 comprises a selector unit, labelled 6 as a whole, designed to form on the top of the pile 4 supported by the elevator table 11 stacks 2 of panels 3 to be transferred to the user station.

The selector unit 6 is mounted on the crossbar 5 and, more specifically, it comprises at least one reference stop 7 for the top of the pile 4 (shown with a dashed line in Figure 4) and a first wedge-shaped rod-like element 8 driven transversally to the pile 4 in the feed direction A in such a way as to separate from the pile 4 a certain number of panels 3 at the top to form the stack 2.

It should nevertheless be stressed that the separating action of the first wedge- shaped element 8 is followed by a coordinated downward movement of the elevator table 11 (in a vertical direction V relative to a fixed plane 12) so as to create a gap S around the first wedge-shaped element 8. This possibility of coordinated movement also makes it easier for all the panels 3 in the stack 2 to be uniformly selected.

The numeral 60 in Figure 1 denotes further reference stops located in the proximity of the side of the pile 4 of panels 3 opposite the panel 3 selection side (that is to say, the side nearest the user station).

These reference stops 60, usually one or more blocks, act on the outer edge of the selectable panels 3 at the top of the pile 4 when the first wedge-shaped element 8 is inserted into the pile 4.

This is possible by adjusting the reference blocks 60 in height to stop the panels 3, preferably against one of their vertical sides, in order to prevent unwanted movement of the panels 3 penetrated by the first wedge-shaped element 8.

The apparatus 1 may also comprise first and second means, labelled respectively 51 and 52 as a whole, for gripping the panels 3, said means not described herein since they are not strictly part of the invention.

A second wedge-shaped element 9, similar to the first element 8 and forming another part of the selector unit 6 may be connected to one of these gripping means (normally grippers).

However, said second element 9 may move either in the direction of feed A, or relative to the crossbar 5 along a first horizontal direction T, longitudinally to the crossbar 5 itself (this solution and its construction details are described in detail in Italian patent application BO2006A000238 by the same Applicant and, therefore, they are only briefly referred to herein).

The apparatus also comprises presser elements 10, which can be inserted between the top of the pile 4 and the selected stack 2, and which act on the top of the pile 4 after the gap S has been formed. In this way, the presser elements 10 generate a compression force F on the pile 4 to hold the panels 3 at the top of the pile 4 when the stacks 2 are fed by the crossbar 5.

In a first, non-limiting construction solution, illustrated in Figures 2 and 3, the presser elements 10 may be connected to the fixed surface 12, being close to the end of the pile 4 furthest from the user station, relative to the direction of feed A, and below the crossbar 5 and the selector unit 6.

More precisely, these presser elements 10 may comprise a compression plate 13 connected to first movement means 14, said means being positioned along a supporting column 15 and designed to allow the plate 13 to move between two limit positions, respectively, lower, operating in which it makes contact with and presses the top of the pile 4, and raised, non-operating in which the plate 13 is spaced from the top of the pile 4 (see arrows Fl in Figure 2).

Obviously, it must be possible to insert this plate 13 only after the gap S has been formed. For this purpose, the column 15 pivots, at 15a and at its lower end, at the fixed surface 12 and is controlled by second movement means 16 (a cylinder) designed to allow rotation of the column 15 between a lowered non- operating position, in which the column 15 is spaced from the pile 4 (dashed line in Figure 2), and a raised operating position, in which the column 15 is positioned parallel with the pile 4 and the plate 13 is inserted between the top of the pile 4

and the selector unit 6 (see arrow F2 in Figure 2).

In terms of construction, the plate 13 may comprise an operating contact head 17 positioned transversally to the column 15, and a support 18, parallel with the column 15, and slidably connected to respective column 15 guides 19. The lower end of the support 18 is connected to the rod of a movement cylinder 14, integral with the column 15, and forming the above-mentioned first movement means.

Figures 4 to 6 show an alternative construction more dedicated to the above- mentioned structure of the selector unit 6 comprising the two wedge-shaped elements 8 and 9.

In this specific case, the presser elements 10 may be connected to the crossbar 5 and move, independently of the crossbar 5, at least parallel with the two wedge-shaped elements 8 and 9 along the direction of feed A.

Obviously, the presser elements 10 may belong to a single unit, two units, together with the wedge-shaped elements 8 and 9 or there may be a greater number of them, depending on apparatus operating requirements, without thereby limiting the solution in accordance with the invention.

As shown in Figures 4 to 6, each presser element 10 comprises at least one set of equipment 20 connected to the crossbar 5 and positioned parallel next to the first and/or second wedge-shaped element 8 and 9.

Each set of equipment 20 comprises:

- an arm 21 pivoting, at 21a and at a first, distal end, at a supporting plate 22 slidably connected to a guide 23 which is integral with the crossbar 5. At the distal end, the arm 21 has a head 24 for making contact with and pressing the top of the pile 4;

- a movement unit 25 acting on the supporting plate 22 and on the arm 21 in such a way as to allow the contact head 24 to be inserted between the first and/or second wedge-shaped element 8 and 9 and the top of the pile 4 in coordination with creation of the gap S between a stack 2 of panels 3 and the rest of the pile 4. As Figures 4 to 6 clearly show, the contact head consists of an idle

cylindrical roller 24 connected to the proximal end of the arm 21 in such a way as to allow constant pressure to be applied to the top of the pile 4 during the stack 2 feed stroke towards the user station.

Obviously, each set of equipment 20 present may be connected, to the respective set of equipment 80 for supporting and moving each wedge-shaped element 8 and/or 9.

If connected to the second wedge-shaped element 9, the respective set of equipment 20 may also move transversally relative to the crossbar 5 during its positioning step. The above-mentioned movement unit 25 comprises third movement means

26 inserted between the crossbar 5 and the supporting plate 22 and designed to allow a movement (in both directions), according to the direction of feed A ₅ by the supporting plate 22 between a back, non-operating position (Figure 5), and a forward, operating position (Figures 4 and 6 and arrows F3) in which it is inserted between the first and/or second wedge-shaped element 8, 9 and the top of the pile

4, and in which the arm 21 is parallel with the first and/or second wedge-shaped element 8, 9.

The movement unit 25 also comprises fourth movement means 27, 28 inserted between the supporting plate 22 and an intermediate point 21b of the arm 21 , being designed to allow, respectively:

- a first movement towards the top of the pile 4, when the supporting plate 22 is in the forward, operating position (arrow F4 in Figures 4 and 5), and

- a second movement for contact between the head 24 and the top of the pile 4 so as to press on the top of the pile 4 (arrow F5). To allow these two movements, the fourth movement means comprise two opposite cylinders 27 and 28, positioned vertically, and connected with the respective rod, respectively, to the supporting plate 22 and to the arm 21 so as to control the arm 21, first in the approach position and then in the contact position pressing on the top of the pile 4, and vice versa. In practice, activation of the presser elements 10 begins, after the gap S has

been formed, but, whilst for the first case illustrated there is a vertical rotation of the column 15 to allow insertion of the plate 13 which then presses the top of the pile 4 until feeding of the selected stack 2 is complete, in the second case illustrated the operating movements are different. After the gap S has been formed, the arm 21 of each set of equipment 20 present is moved forward along the direction of feed A so that it is inserted between the top of the pile 4 and each wedge-shaped element 8, 9 already in position.

Preferably, during the forward stoke the cylinder 27 connected to the supporting plate 22 is activated to angle the arm 21 (with predetermined stroke) and avoid interference with the respective wedge-shaped element 8 or 9.

At this point the cylinder 28 may also be activated to determine the compression force F to be applied to the top of the pile 4.

As it moves forward, the crossbar 5 also causes the set or sets of presser equipment 20 to move forwards which, thanks to the cylindrical roller 24, maintains pressure on the first panels 3 at the top of the pile 4 along the feed path.

Just before the crossbar 5 reaches the forward limit position for placing the stack 2 in the user station, the cylinder 28 raises the arm 21 to avoid unwanted contact with the above-mentioned reference stop elements 60.

Therefore, an apparatus with the structure described fulfils the preset aims thanks to the presence of presser elements, which are fixed or can move with the crossbar and are designed to allow guaranteed, precise feed of the panels selected.

This is all accomplished without excessively altering the structure of the crossbar and operation of the crossbar and the selector unit.

The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements.