DESCRIPTION

Field of application

The present invention relates to an accessory device for a numerical control machine.

More particularly, the invention relates to a device for feeding sheets of material to be processed in blade cutting machines, for instance for cutting sheets of material such as fabrics for clothing and hide goods, footwear items, automotive and furnishing articles or non-woven fabrics, leather, natural or synthetic hides, soft or semi-rigid synthetic materials, used for instance for insoles, and the like.

The invention also relates to a numerical control machine for cutting at least one sheet or a multilayer of sheets of material to be processed comprising said accessory device.

Said numerical control machine is preferably of the type comprising:

- a processing chamber or room;

- conveying means adapted to feed the sheet into said processing chamber along a forward direction;

- toll heads adapted to operate on the sheet in said processing chamber. Prior art

As it is well known in this technical field, there are numerical control machines or apparatuses capable of cutting sheets of material in an automated manner according to a predefined cutting pattern. The material to be cut may be for instance a sheet of plastic material, a natural hide, a fabric, a non-woven fabric, a cellulose-based material and the like. The cutting may be performed on a unique sheet or on a plurality of sheets stacked upon each other so as to form a multilayer which is known in the field as mattress.

In particular, these machines are equipped with a conveyor belt capable of moving the sheet to be cut along a plane XY, which will be hereinafter also defined cutting table, and inside a cutting chamber, which is provided with cutting tool heads actuated by computerized means for processing the material.

The sheet or sheets to be cut in the machine can be unrolled from rolls or other supports placed at a short distance from the mouth of the machine, in this case the multilayer is prepared beforehand off-line or in front of the machine by overlapping the sheets on a table of adequate length. However, working in particular with fabrics, the use of processing relatively short accordion-folded sections of material (for example few meters) near the mouth of the machine and resting on a support table has become common.

These relatively short sheets must be loaded in the machine with a higher frequency than that of the multilayer formed from the rolls.

Usually, the short free side of a sheet of material a few meters long is placed on the conveyor belt only by an initial section, for example of about one meter, to be attracted and cut during the subsequent forward movement of the belt, which simultaneously involves the recovery by dragging of the remaining material.

When a new sheet of a multilayer of sheets is placed on the machine at the beginning of a new processing, it is necessary to respect some precautions listed below:

- taking care of the mutual alignment of the multilayer sheets so that the various layers are aligned to each other to avoid having to reduce the width of the cutting field and / or cutting outside some layers;

- taking care of the lateral alignment of the sheet or sheets with respect to the movement of the belt; namely, making sure that the sheet does not drift towards the right or left sides of the cutting chamber as it moves forward on the belt;

- properly preparing the arrival of the following sheet, especially if multilayer, for instance on the loading plane outside the conveyor belt to avoid interrupting or slowing down the cutting flow.

Generally, the material to be cut is held on the conveyor belt by suction means arranged below said belt and kept in operation while the belt moves forward, so as to ensure the desired holding of the sheet.

However, prior to the intervention of the suction means, i.e. when the multilayer is between the loading plane and the mouth of the machine, it is often necessary for one or more operators to intervene in order to take care of the feeding to the conveyor belt without misalignments between the sheets.

Essentially, the mattress of sheets is manually moved from a preparation plane towards the mouth of the cutting machine and for this operation two people are usually needed.

More particularly, in the clothing field the mattress of fabrics is usually placed on a perforated paper sheet to facilitate the material holding suction. This paper sheet is usually slightly bigger than the mattress and, at the right moment, the operators make the mattress of sheets slide on the cutting machine by pulling the perforated paper sheet.

The technical problem underlying the present invention is to provide an accessory device for simplifying the feeding of sheets of material to be cut in numerical control machines, device which has structural and functional features so as to allow making the passage of the sheet or of the multilayer from the loading plane to the mouth of the machine extremely fluid, thus overcoming the drawbacks which still affect the known machines.

Another object of the invention is to keep the mattress of sheets that is loaded into the machine compact and correctly stretched. A further object of the invention is to provide a numerical control machine which integrates, at least in a use condition, an accessory device to facilitate the feeding of sheets in multilayer according to the above mentioned features.

Summary of the invention

The solution idea underlying the present invention is to provide an accessory device which performs the function of interposition plate between a foldaway sliding loading plane for the sheet or multilayer of sheets below the plane during the first feeding step to the conveyor belt of the machine.

In other words, said interposition plate partially extends the loading plane towards the mouth of the machine in order to allow, after having retracted the plate, pressor means to hold the free end of the multilayer, when the conveyor belt is stationary, then drawing back the entire loading plane and thus leaving a sufficient portion of the multilayer on the conveyor belt.

The above technical problem is solved by an accessory device for simplifying sheets of material to be cut into numerical control machines, comprising:

- a loading plane associated with a front portion of the machine to receive the free end of said sheets;

- an interposition plate supported parallel to the plane and partially projecting towards the machine;

- means for adjusting the projection of the plate with respect to the plane.

Advantageously, the plate is slidingly supported below said plane on opposite guides.

More particularly, the guides are obtained in undercut at the lateral edges of the plane, below it. Essentially, the plate is slidingly foldaway guided below the plane.

Furthermore, the plate is made of a synthetic-plastic material with low surface friction. Said material may be nylon or, alternatively, polyethylene. The above means for adjusting the projection of the plate with respect to the plane comprise at least one lever connected to a side of the plate and hinged to the plane.

Alternatively, said means comprise at least one rack associated with a side of the plate and engaged to a gear actuated by an electric motor. It is also worth noticing that the plane is moved in horizontal translation in a direction parallel to the forward direction of the sheets between a retracted position, in which it is spaced apart from a proximal end of the conveyor belt of the machine to a feeding position, in which it is partially overlapped to said proximal end. It is clear how the above structure is particularly effective since the interposition plate partially extends the loading plane just during the first support and feeding step on the proximal portion of the belt at the mouth of the numerical control machine.

Thanks to said structure, the accessory device according to the invention may be associated with foldaway sliding parallel to the loading plane which, in turn, may be associated in a folding manner on the front of the machine below the proximal portion of the conveyor belt.

Of course, nothing prevents from having a loading plane which is structurally independent from the numerical control machine and from equipping said loading plane with the interposition plate according to the present invention.

The above mentioned technical problem is also solved by a numerical control machine for cutting at least one sheet or a multilayer of sheets of material to be processed, comprising: - a processing area (preferably defined by a chamber or room);

- conveying means adapted to feed the sheet into said processing area along a forward direction;

- tool heads adapted to operate on the sheet in said processing area; characterized in that it further comprises:

- clamping means for clamping said sheet or multilayer arranged at least at the mouth of said cutting chamber and movable between a non operating position, in which they are at a determined distance from the surface of the sheet or from the surface of the conveyor belt, and an operating position in which at least a lower edge is in retention abutment onto the surface of the sheet by pressing it on the conveyor belt;

- as well as an accessory device associated with said machine and structured according to what has been described above. Said accessory device may be a part of the machine, possibly also integrated thereto; or alternatively it may be a distinct device associable with the machine in the use conditions.

The above machine may comprise a front device equipped with a support plane for the sheets which is foldable between: a vertical rest position; and a horizontal operating position in which it is in substantial continuity with the conveying means.

Advantageously, the accessory device may be mounted in a lower position and may be horizontally movable between an extended position, in which it cantilever projects below and close to the loading plane, and a retracted position in which it is foldaway hidden below the loading plane.

The features and advantages of the device and machine according to the invention will become apparent from the following description of some exemplary embodiments given by way of non-limiting example with reference to the accompanying drawings.

Brief description of the drawings

In those drawings:

- figure 1 shows a perspective view of a machine equipped with an accessory device according to the first embodiment of the present invention, wherein the accessory device is provided and configured to facilitate the feeding of the sheets of material to be cut;

- figure 1A shows a perspective view of a numerical control machine without the accessory device according to the present invention and in which front and rear elements are in the open position;

- figure 2 shows a perspective view in an enlarged scale of figure 1 in a loading start and overlapping configuration of the sheets to be cut;

- figure 3 shows a perspective and rear view of the machine of figure 1 in which the accessory device is folded away below the front portion of the machine;

- figure 4 shows a perspective view of a machine equipped with an accessory device according to the first embodiment of the present invention, wherein the accessory device is also configured to convey four rolls of material in a configuration overlapped two by two;

- figure 5 shows a perspective view in an enlarged scale of figure 1 in a forward configuration of a loading plane equipped with the accessory device of the invention;

- figure 6 shows a further perspective view of the machine according to the invention in a further operation step thereof;

- figure 7 shows another perspective view of the machine according to the invention in a further operation step thereof;

- figures 8 to 10 show respective perspective views, in partial section, of details of the accessory device of the present invention in different operating forms and configurations;

- figure 1 1 shows a perspective view of a machine equipped with an accessory device according to a second embodiment of the present invention, said machine being equipped with the accessory device of the invention.

Detailed description

With reference to those figures, a numerical control machine for cutting sheets of material according to the present invention with an accessory device 9 that is removably associated with the apparatus 1 is globally and schematically indicated with reference number 1.

The figures represent schematic views and are not drawn to scale, but instead they are drawn so as to emphasize the important features of the invention. Moreover, in the figures, the different elements are depicted in a schematic manner, their shape varying depending on the application desired.

Moreover, the same reference numbers refer to elements that are identical in shape or function. Finally, particular features described in relation to an embodiment illustrated in a figure are also applicable to the other embodiments illustrated in the other figures.

In its more general form, the machine 1 is adapted to process, and in particular is adapted to automatically cut, folding or flexible sheets 2 of material, for instance fabrics for clothing items or accessories, leather, natural or synthetic hides, non-woven fabrics, cellulose-based material, other synthetic materials and the like.

In the context of the present invention, the term“sheet” indicates any element of any shape and material, having a substantially two- dimensional size and a certain thickness (generally reduced), which must be cut through the machine. As it will be noticed hereinafter in greater detail, often the cutting of a plurality of sheets stacked on top of each other so as to form a multilayer, and having substantially coincident shape and size, even if not necessarily, is often performed. The machine 1 is thus a numerical control machine equipped with data and program memories. In particular, the apparatus 1 comprises a control unit 21 including said memories and suitably programmed and configured for the management and automatic control thereof. The control unit 21 may be for instance an integrated computerized unit or may be external to the machine 1 and operatively connected thereto. Furthermore, it is noticed that the control unit may be a unique central unit or may comprise a plurality of local units, considered as controllers associated with various actuators arranged on and in the machine.

Conventional user interfaces 30, 35 are available to the operators to activate or program operating algorithms of the machine. Said interfaces 30, 35 are supported both at the front portion and at the rear portion of the machine, possibly active on the relevant front and rear components.

In general, the machine 1 of the present invention comprises a frame F, made for example from a metallic material, which supports and encloses the main components of the machine.

More particularly, the machine 1 comprises a cutting chamber or working room 3 inside which the sheet 2 processing occurs on a working plane a. The cutting chamber 3 has a loading inlet 4 through which the sheet 2 is fed and an unloading outlet 5 from which the cut portions of said sheet 2 are recovered.

Furthermore, the apparatus 1 comprises a motorized conveyor belt 6 which crosses the cutting chamber 3 from the inlet 4 to the outlet 5 and is adapted to feed and convey the sheet 2 into said cutting chamber 3. In a preferred embodiment the conveyor belt 6 is extended horizontally.

The conveyor belt 6 may be covered by a sacrificial and breathable support layer (not shown in the figures) which is subjected to multiple cutting steps during various processing and which is periodically replaced. Below the support layer, conventional suction means are provided (also not illustrated in the figures), which allow holding the sheet 2 in place on the conveyor belt 6 during the forward movement due to suction. Possibly, a perforated paper sheet is provided as first layer to facilitate the cutting, creating a better contrast for the blade.

Inside the cutting chamber one or more toll heads (not illustrated), which are adapted to operate on the sheet 2 for the cutting, are active.

In figure 1A, the sliding or forward direction of the conveyor belt 6 is indicated as direction Y, whereas the direction transversal thereto is indicated as direction X. In other words, the direction Y identifies the direction along which the sheet is moved by the conveyor belt 6, and the arrow A in figure 1A identifies the feed direction of said sheet.

The machine 1 according to the invention is equipped with a closure element 10a, 10b both on the inlet 4 of the cutting chamber 3 and on the outlet 5 of the cutting chamber 3.

Said closure element may be for instance a glass or plexiglass plate or screen connected to the frame F of the apparatus 1, or equipped with its own frame which is in turn connected to the frame F.

An object of the closure element is to isolate the cutting chamber 3 during the processing steps and at the same to protect from noise the operators close to the machine. However, for the purposes of the present invention the movement of the front screen 10a in cooperation with the accessory device 9 will also be used.

The front closure element 10a is movable between a first position or open position (as shown in figure 1A), in which it is possible to access the cutting chamber 3 from the inlet 4, and a second position or closed position (end-stroke position, shown in figure 7), in which a lower edge 16 is close to the working plane a.

In practice, the closure element 10a is movable towards and away from the working plane a.

When the closure element 10a is in the closed position, with the edge 16 close to the working plane a, not only is the access to the cutting chamber 3 prevented, but it is also retained, when the conveyor belt 6 is stationary, the end free rim of the mattress of sheets 2 prior to proceeding with the cutting operations.

In this way, the front screen 10a cooperates with the accessory device 9 to facilitate the loading of the single sheet 2 or of the mattress of sheets, as it will be apparent from the rest of the description.

Now with particular reference to the examples of figures 2 to 7, the expedient advantageously adopted in the apparatus 1 to more easily feed and suitably position the sheet 2 on the conveyor belt 6 is now described in detail.

As above stated, according to the present invention, the machine 1 comprises an accessory device 9 to facilitate the feeding of the sheets 2 of material to be cut.

Said accessory device 9 is associated with the machine 1 and comprises at least one loading movable plane 14 supported in the operating position close to a proximal end 13 of the conveyor belt 6 through a suitable support structure 25 associated and connected to the lower part of a front portion 20 of the frame F of the machine 1.

The movable plane 14 is substantially a rectangular- shaped plate support, on which surface the free rim of the short side of the sheet 2 to be loaded on the conveyor belt 6 is arranged. Optionally lateral sides 39, 41 are provided on both sides of the movable plane 14 to facilitate the lateral alignment of the sheet 2 or, more particularly, of a multilayer formed by the stack overlapping of the sheets 2. The positioning of said lateral sides 39, 41 is adjustable by means of a graduated scale.

The movable plane 14 is movably guided from a rest position, in which it is vertically extended close to the above lower front portion 20, as shown in figure 3, to an operating position in which it is horizontally extended.

In the patent figures, except for figure 3, the movable plane 14 is always represented in the horizontal operating position. Translation motorized means of the movable plane 14 for actuating said plane are provided between the two horizontal extension extreme positions. Said motorized means are electric motors, for instance brushless motors or the like, which are adjustable with particular precision and interlocked to the control unit 21 of the apparatus 1.

The plane 14 is thus movably guided on an essentially horizontal plane between a loading retracted initial position (figure 4) and a release final and extended position (figures 5, 6 and 7) in which it extends up to reaching the cutting chamber 3.

It is worth noticing that the plane 14 is also foldable in order to be compacted close to the lower and front portion 20 of the frame F of the machine 1, as shown for instance in figures 1A and 3. In this compacted position, which is useful for instance to transport the machine 1 or in some processing of hide sheets when the plane 14 only represents an obstacle, the plane 14 is manually folded below the proximal ends 13 of the conveyor belt 6.

However, it is possible to provide motorized means, and related support guides, to actuate the movable plane 14 in roto-translation from a rest laying position and to make it take up an operating position in which it is coplanar, or it is partially above the proximal end 13 of the conveyor belt 6. In the rest position of figure 1A or 3 the plane 14 is folded away parallel to the lower front portion 20 of the frame F.

The movable plane 14 is also configured to facilitate the feeding of a sheet 2 to be processed on the conveyor belt 6.

In this regard, the plane 14 is equipped with the accessory device 9 of the present invention which takes the form of an interposition plate 8 extending parallel to the plane 14, below it.

Said plate 14 is made of a synthetic-plastic material.

In an embodiment said plate 14 is structured with a nylon sheet. What matters for the purposes of the present invention is the very low surface friction coefficient of the plate 14, which allows slipping it even when there is a pressure on the overlying mattress of sheets.

In an alternative embodiment the plate 14 is of polyethylene (PE) or polyzene.

Polyzene is known among the plastic materials for its multiple properties such as: resistance to impact, to wear, low friction coefficient, resistance to corrosion and to chemical products. Furthermore, said material has a good dimensional stability and is easily workable and weldable.

For the purposes of the present invention a PE polyene plate with molecular density of 300 to 1000, preferably PE 1000 with low friction coefficient and high impact resistance, may be used.

Advantageously, the plate 8 is sliding below the plane 14.

More particularly, the plate 8 is supported by two opposite guides 42, 44 obtained in undercut at the lateral edges of the plane 14, below it. The plate 8 is sliding on the opposite guides away from and mutually towards a proximal edge 40 of the plane 14.

Alternatively, it is also possible to provide at least one track central support of the plate 8, possibly tapered towards the projection direction, or at least one pair of track supports extended parallel but not necessarily at the two opposite lateral ends.

What matters for the purposes of the present invention is that at least one section or band 10 of the plate 8 can be extended in distal projection towards the loading direction emerging from the underside of the plane 14.

The plate 8 is essentially rectangular-shaped with dimensions substantially corresponding to those of the plane 14, or slightly less in terms of longitudinal extension.

The plate 8 is intended to partially project towards the direction of the cutting chamber 3 below the plane 14. The distal portion of the plate 8 emerging from below the plane 14 is indicated with reference number 10 and represents a support band for the free end of the sheet 2 or of the multilayer of sheets 2.

In the operating position the band 10 projects by a few centimeters from the distal end edge 15 of the plane 14, for instance by a section less than 10 cm, without this obviously representing any limitation for the Applicant’s rights. The projection may be chosen based on the type of material to facilitate retraction, avoiding upsetting the alignment of the sheets that make up the mattress to be processed.

The opposite side of the plate 8, namely the proximal end portion, is constrained to a lever 45 which has an end 46 hinged to a lower lateral edge 48 of the plane 14.

More particularly, a lever 45 is provided at each proximal angle of the plate 8 located close to the proximal edge 40 of the plane 14.

The two opposite levers 45 have respective control rods 49 emerging from slotted portions of the plane obtained from opposite lateral parts close to the proximal edge 40. The control rods 49 can be gripped by an operator.

The lever 45 is angularly movable with a predetermined angular excursion from a rest position, shown in figure 10, in which the plate 8 is completely retracted below the plane 14, to an operating position (figures 8 and 9), in which the plate 8 projects beyond the distal edge 15 of the plane 14, leaving the support band 10 exposed.

In an embodiment provided by the present invention the movement of the movement of the plate 8 is completely automatic and performed by motorized means interlocked to the control unit 21 of the machine 1.

For instance, motorized means for moving the lever 45, which are interlocked to the control unit 21 of the machine 1, may be provided.

Alternatively, the lateral portions of the plate 8 may be equipped with a respective rack (not shown) coupled to a corresponding gear actuated by an electric motor, for instance a step motor.

Each rack is longitudinally mounted on a corresponding guide 42, 44 below the plane 14 and actuated as one with the opposite rack to adjust the projection of the plate 8.

An alternative embodiment using a unique rack on a side of the plate, clearly with a unique drive motor, an opposite slide associated with the other side of the plate 8 and sliding in the corresponding guide 42 or 44 may be adopted as a further alternative.

It should also be noted that the movable plane 14 is movably guided towards and away from the proximal end 13 of the conveyor belt 6.

Still more particularly, the movable plane 14 is moved in horizontal translation in a direction parallel to the movement direction of the conveyor belt 6 (i.e. the direction Y) and is particularly movably guided between a loading retracted position, in which it faces the proximal end of the conveyor belt 6, as illustrated in figure 4, and a feeding and release position, in which it is partially overlapped to the conveyor belt 6, as shown in figure 5.

More particularly, when the movable plane 14 is in the loading retracted position (figure 4), the mattress of sheets 2 may be dragged and extended on the plane 14 until the end of the free rim (in case of a single sheet) or the overlapped ends of the rims of the multilayer coincides with the projecting outer edge of the band 10 of the plate 8.

The programmed forward movement of the movable plane 14 leads to a dragging of the mattress of sheets towards the cutting chamber until it reaches a predetermined position, shown in figure 5, in which the exposed band 10 of the plate 8 is located on the projection of the front screen 10a.

At this point it is possible to retract the plate 8 and, obviously, the band 10 as well, which slides below the free end of the mattress of sheets 2 thanks to the low friction coefficient. By actuating the lever 45 (manually or automatically), the plate 8 is retracted so that the band 10 returns to be completely folded away below the plane, slipping out from below the free end of the mattress of sheets, thanks to the very reduced surface friction.

Only after this passage, the front screen 10a which blocks the mattress of sheets in position is lowered.

At this point, while the material to be cut remains clamped and trapped by the lower edge 16 of the front screen 10a, it is possible to retract the plane 14.

At this point, after having lowered the front screen 10a, it is possible to also retract the plane without the material being moved, thus leaving it laid on the conveyor belt by a significant portion, for instance of about 40cm.

Alternatively, it is possible to provide a crosspiece (not shown in the drawings) having the function of clamping the free end of the mattress of sheets, or anyway of the end portion, releasing the screen from the function of holding the mattress when the plate 8 has been retracted.

In general, clamping means may also be provided, which are arranged laterally to the plane 14, but integral with the machine, to laterally hold the mattress of sheets during the retraction step of the plane. Said means may be supported by lateral longitudinal members supporting the sliding guides of the plane.

Essentially, the machine of the present invention comprises means for clamping said sheet or multilayer, arranged at least at the mouth 4 of said cutting chamber 3, which are movable between a non-operating position, in which they are at a determined distance from the surface of the sheet or from the surface of the conveyor belt 6, and an operating position, in which at least one lower edge abuts onto the surface of the sheet almost in adherence to the conveyor belt.

In any case, thanks to the presence of the accessory device 9, the sheet 2 or the multilayer of sheets 2 may be positioned on the conveyor belt 6 in a simple and effective manner and in a semi-automatic manner. In fact, the movable plane 14 is substantially cantilever supported outside the machine 1 and makes the activity of preparing the new sheet to be loaded easy for the operator, for instance gripping the free ends and dragging the sheet from the supporting roll or from the folded material.

Furthermore, the accessory device 9 also makes the mutual alignment and overlapping of the various layers of sheets 2 and their alignment with respect to the movement of the conveyor belt easy.

Suitably, the movement of the movable plane 14 is controlled in an automated manner by the control unit 21 and, in an embodiment, it is synchronized with that of the conveyor belt 6 and with that of the front screen 10a.

Now, for the sake of completeness of description, and particularly referring to the example of figure 10, it is noted that the movable plane 14 laterally has two arms 60 hinged with respect to as many uprights 61 integral with the support structure 25.

A further accessory 50 or 50’ for supporting the rolls of sheets 2 is associated with the plane 14; said accessory comprises two longitudinal members 51, a plurality of planar attachments 54 associable with said longitudinal members 51 and support 53 and guide 56 transversal bars supported by the above attachments 54 located in opposite position on the two longitudinal members 51.

All these elements are variably configurable, as exemplified by the figures, to support one or more rolls 57 of the material 2 to be cut; said rolls are placed on the support bars 53 and in different positions. The use of more rolls 57 allows simultaneously unrolling more layers of material 2 to make a multilayer or mattress to be cut in the machine 1.

The guide bars 56 allow the rolls to be returned to a substantially continuous planar orientation with respect to that of the conveying means 6, avoiding interference between unwound sheets from successive rolls 57. The longitudinal members 51 are preferably made as metal sections having rectangular or square section, and are cantilever fixed to the machine 1 or to the movable plane 14.

The attachments 54 are a plurality of pairs comprising a right attachment and a left attachment specular to each other. The attachments 54 of each pair must be associated facing opposite the two longitudinal members 51, and provide different main 52 and secondary 55 slots, which are adapted to support the support 53 and guide 56 transversal bars, respectively.

The attachments 54 are removably mounted on the longitudinal members 51, so that in the various configurations of the device 50 they can be used in a different number.

Each attachment 54 is preferably made of metal sheet and thus has a substantially planar conformation.

It has two wings, an upper one 54a and a lower one 54b, which are opposite and substantially specular to each other. Both wings have a main slot 52. Said slot is made as a C-shaped recess, preferably made by shearing, which leads to a lowered seat where the transversal bar 53 is housed.

The accessory 50 or 50’ is illustrated in the enclosed figures in two different embodiments, which are different from each other just in the different arrangement of the rolls above and below the plane or all aligned to each other as shown in figure 1 1. The previous description applies for both embodiments.

In both embodiments the accessory 50 is associated with the end of the movable plane 14 when it is in the raised configuration.

In this case, the plane defined by the longitudinal members 51 is substantially at the height of the plane of the machine 1 or slightly higher, namely it is a feeding plane which is substantially continuous with respect to that of the conveying means 6 except for a slight difference in level represented by the partial overlap of the plane 14 and of the related plate 8.

The longitudinal members 51 are introduced, in this case telescopically, into the arms 60 of the movable plane, which are advantageously configured as hallow sections. The longitudinal members 51 may be blocked in position more or less extracted with respect to the arms, according to the needs of use of the machine 1.

Obviously, a person skilled in the art, in order to meet particular needs and specifications, can carry out several changes and modifications to the invention, all included in the protection scope of the invention as defined by the following claims.