Technical Field The preferential application, even if not a limitative one, concerns the manufacturing of wooden panels and the like such as hardboard, medium density etc., in the field of furniture and in particular panels for furniture, preferentially small doors, which as it is known should be moulded (shaped in their profiles) and eventually provided with mirrors (shaped inside in order to obtain the known mirrors or central small mirrors).

Background Art For these types of manufacturing the panel to be worked is generally locked on a working table provided with a large plurality of holes and beneath which the vacuum is obtained in order to lock, by pulling it, the panel to be worked.

It very often occurs that, because the panels to be worked are often of different size, it is necessary to use an under-panel which has such an extension to cover all the holed plane of the working table with a series of holes on said under-panel which extend only inside of the extension surface of the overhanging panel to be worked.

This obviously for avoiding that the holes beyond the panel covering range remain uncovered and that the vacuum suction effect for the panel locking is reduced.

Such a system though, requires to change always the under-panel each time that the panel to be worked needs to change dimension.

In fact there is not only the problem of allowing the functioning only

of the vacuum holes concerning the surface of the panel to be worked, but also that of supplying the panel to be worked with a rise in order to allow a rational and complete profiling and shaping of the same panel.

Therefore, when the panels are manufactured by the flanging milling machines (moulding machines), the flanging milling machine may protrude beyond the level of the lower surface of the panel to be worked.

For such reason, the under-panel (more or less of the same material) also acts as a spacer and thus it also is etched by the tool jutting.

This fact forces the operator to change the under-panel when the type of panel to be worked changes.

Purpose of the present invention The purpose of the present invention is that of obviating the above mentioned drawbacks and in particular of realizing a vacuum fixing plane for panels to be worked of any size and with no need of placing an under-panel beneath it.

Essence of the invention The problem is solved and the purpose reached as claimed by realizing a plane equipped for the fixing on itself by attraction of a panel to be worked, of the type in which said plane is provided with a plurality of suction holes for a vacuum action, characterized in that: -said suction holes are made within respective small pistons placed in lines, which: (are provided with fluid-dynamical lifting and lowering means; (during the lifting they open the suction passage and during the lowering they close it; -said fluid-dynamical lifting and lowering means consist of a series of fluid-dynamical ducts which connect each small piston with the

adjacent one, along two orthogonal co-ordinates (X, Y) one for the lifting and one for the lowering of the respective small pistons lines, and this in such a way that by working on one side with a lifting pressure difference and on the other with a lowering one, the concerned small pistons lifting by differential pressure is determined only in that extension of small pistons programmed for a corresponding panel to be worked.

Advantages Thus the immediate advantage of lifting the panel to be worked from the underlying supporting plane and simultaneously applying the vacuum suction only to the small pistons lifted beneath the panel to be worked is obtained, while the other small pistons will remain lowered, thus allowing also an easy manufacturing of the whole panel back.

Thus all the working and manufacturing technology is simplified and improved in productivity.

These and other advantages will appear from the following description of a preferential explanatory solution of the realization related to the enclosed drawings.

Figure 1 is a top schematic view of the fixing plane according to the present invention (also more equipped planes of this type on a milling machine may be provided).

Figure 2 is an enlarged A-A cross section view, of a part of the plane as in Fig. 1 concerning the axial section of a small piston and a respective adjacent stop or positioner of the plane edge; Figure 3 is an orthogonal cross section view; Figure 4 is a cross enlarged view on the A-A axial plane of a positioner and respective suction cup of one of the suction devices.

As it can be seen in the figures, with 1 is generally indicated the suction

cylinders 2 supporting plane while with 3 the stops or stopping devices or positioners are indicated.

X indicates the suction cylinders 2 lines in one direction and Y indicates the lines in orthogonal direction.

Both the suction cylinders 2 and the positioning ones (3) are shaped like a piston stem (31,20).

The positioning ones have an upper contact ring 311.

In particular the suction small pistons 2 are placed in orthogonal lines, X, Y, forming a matrix of small pistons passing within the supporting plate made up of four pack plates 10,11,12,13.

The bottom plate 11 is hollow for the burying of the drawer-like small piston, in order to interact in opening or closing with a duct 1101 for allowing the vacuum suction passage (201,210) at the suction cup top 21- 214 for locking the above panel when the small piston 2 is lifted.

When the small piston 2 is lowered the vacuum suction access 1101 is closed as shown in the figure.

The piston stem 20 is guided by guide bushes 17,18,19,14.

The upper bush is fixed by bolts 15 for locking and extraction for maintenance and replacement.

The whole is provided with sealing gaskets 16.

The suction cup 21,211 engages on the top 202 of the piston stem 20 and the whole is covered by the cup 22 which also acts as a contact delimiter for the upper panel rest.

Once the small piston 2 is lifted, the panel will rest on the cup 22 and the suction cup will adhere supplying the suction through 210-201-1101.

A known art device will start up the vacuum by a known suction pump.

According to the invention, for each small piston a double crossed channel"C"between the bushes 17 and 14 is provided (visible only in

fig. 4 because the other one is absolutely alike but orthogonally symmetrical).

Each channel"C"intercommunicates with a whole line of small pistons (X) while an orthogonal similar channel interconnects each orthogonal line Y of the same small pistons.

In other words, an intercommunicating lifting line"C-X"and an intercommunicating lowering line"C-Y"or vice versa is obtained.

Working mode For determining the lifting only of the concerned small pistons surface, presuming that the X lines control the lifting and the orthogonal lines Y control the lowering: -a lifting pressure XP is applied to the number of concerned lines X and all the small piston of these lines X will be lifted, all of them activated by the vacuum suction; -a lowering pressure XP>XP is applied in the orthogonal lines which do not concern the attraction surface so that by differential pressure the corresponding not concerned small pistons are forced to remain lowered (this operation may be suitably carried out before the other, reducing a movement and obviating to pressure losses).

For being sure that the small pistons 2 remain always lowered, a slight pressure pY may be applied in the Y direction to all the small pistons, in such a case the lifting pressure PX will have to be higher than pY.

Of course this is an operational example, being possible to change the combination as wished, this not being a limitation for the purposes of this invention.

Further details of the preferred embodiment.

The small pistons 2 are lifted by a program selecting the lines of small pistons to be activated, so to obtain a square or rectangular shaped area

where it is possible to lay the piece to be worked.

The pieces resting area, may be automatically obtained by inputting the piece size in the suitable program.

The advantage of this system thus consists in being able to carry out contouring operations on pieces having different size without having to make the suitable fixing forms for each of them.

This system, allows anyway to work with the traditional forms which in this case will be placed directly over the small pistons.

There may be more planes equipped with small pistons of this type for equipment, and these may be activated all together or separately.

Each equipped plane is endowed with positioning lateral small pistons, four of which are necessary for positioning the piece one on the left side and one on the lower side. These positioners (3) have three different diameters, for a smart interaction with the suction small pistons and a pieces centring optimization.

Particularity of the workable pieces.

The contouring manufacturing carried out will only be straight along the horizontal axes X, Y and Vertical one, or such to form square or rectangular figures with their sides placed parallel to the axes.

Nothing prevents this solution from allowing the carrying out of rounding, bending and chamfering operations, not interfering with the prior art.

In the manufacturing which involves also the lower part of the piece, e. g. with"C"shaped milling machines which laterally reenter under the piece, for preventing the resting small pistons from being damaged by the tool, a suitable re-entry may be provided in the program.

The program may also provide for selecting automatically the positioners and the suction small pistons.

Some alarm means associated to sensors for the respective small pistons may be provided, thus allowing to obviate the risk of damaging equipment and tools.

The vertical amplitude of the small pistons is of about 10 mm.

The automatical optimization function of the small pistons, is carried out by means of suitable program controls which will start at the beginning of the operations included the piece width variables ex. X, piece length ex. Y or vice versa, and lateral re-entry of the tool under the piece.

By the program also the prearrangement of the positioners 3 lifting may be provided.

Each area is advantageously made up of 26 small pistons lines in one direction and of 9 small pistons in the other direction, but it is clear that this number may vary as wished. The first two lines are those close to the operator and thus to the positioners 3.

For obtaining the wished hollow area, it will be only necessary to select the two delimiting lines, referring to the respective positioners.

The positioners may be selected on the base of the wished distance between themselves and the suction small pistons.

The execution details may anyway vary.