DESCRIPTION The present invention relates to an apparatus for continuously feeding and unloading sheets into/from an operating machine such as a punching machine/platen and/or pressing machine.

It is known that, in the technical sector relating to cutting, incision and/or hot-pressing of sheets of paper, cardboard and the like, performed by means of so-called punching machines/platens and/or pressing machines, there exists the dual need to:

- to feed into the machines the sheets to be processed by means of suitable apparatus having hinged arms which remove the sheet from corresponding stacks, arranged in the vicinity of the machine; and

- extract the processed sheets from the machine so as to stack them in special storage zones from where the formed stack is then conveyed away for subsequent processing and packaging.

It is also known that this operating sequence is performed in a discontinuous manner, it being required to stop the pressing machine, with consequent cycle down time, whenever the stack of incoming sheets is used up and must be replenished.

The technical problem which is posed, therefore, is to provide an apparatus for loading/unloading sheets into/from operating machines, such as pressing machines/platens, which is able to allow replenishment of the stack of sheets to be fed to the machine without the need to stop the latter, thus making a continuous working cycle possible such as to eliminate the machine stoppage downtime at present required with the apparatus of the known type.

In connection with this problem it is also required that this apparatus should have a compact size, be easy and inexpensive to produce and assemble and be able to be easily installed also in association with the already existing machines without the need for substantial modifications thereof.

These results are achieved according to the present invention by an apparatus for continuously feeding and unloading sheets into/from an operating machine, comprising a first device, for storing, in a stack, the sheets to be processed, having associated means for selecting and means for removing individual sheets from said stack, a device for conveying the sheets extracted from the stack to a pick-up zone for insertion in the machine and a second device for storing and conveying the finished sheets extracted from the machine, having means for conveying them from a storage zone to an exit zone of the apparatus . Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the accompanying drawings, in which:

- Figure 1 shows a schematic cross-section along a longitudinal vertical plane of the apparatus according to the present invention;

- Figure 2 shows a schematic cross-section along a plane indicated by II-II in Fig. 1; and

- Figure 3 shows a partial top plan view of the apparatus according to Fig. 1. As shown, the apparatus for continuously feeding and unloading sheets 1 into/from a platen 10 - with which there is associated a sheet-insertion/extraction device 10a having a first arm 11 for gripping/introducing the sheet Ia into the platen and a second arm 12 for gripping and unloading the finished sheet Ib

comprises substantially:

- a first device 100 for storing, in a stack 1, the sheets Ia to be processed, having associated means 110 for selecting and means 120 for removing individual sheets Ia from the said stack 1 and comprising a device 200 for conveying the sheets Ia to the zone for picking up by the loading arm 11 of the machine 10, and

- a second device 300 for storing and conveying the finished sheets Ib, in turn having means 320 for conveying the said sheets Ib, from the zone where they are released by the unloading arm 12 of the machine 10, to the exit zone for conveying away for the subsequent packaging operations. Solely for the sake of convenience of the description a longitudinal direction X-X parallel to the direction of forward movement of the sheets and a rear part (P) and a front part (A) of the apparatus respectively corresponding to the part furthest away from and to that closest to the platen 10 will be assumed. In greater detail said device 100 for storing the sheets Ia to be processed envisages a seat 130 delimited by corresponding movable partitions 131 able to define the zone for formation of the stack 1 depending on the size of the sheet Ia, said seat 130 being positioned in the rear zone of the storage device 100.

Downstream of the seat 130, in the direction of feeding of the sheet Ia, means 110 for selecting the sheet Ia are also envisaged, said means being able to retain the stack 1 and allow the extraction of one sheet Ia at a time .

As illustrated, the sheet Ia which is fed forwards is taken from the bottom of the stack 1 via said pick-up means 120 which, in a preferred embodiment, envisage first pick-up belts 121 with a high coefficient of

friction and second belts 122 able to convey the sheet Ia, already extracted, to the conveyor device 200, in turn provided with belts 221, the outward travel path of which terminates in the vicinity of a stop 221a for retaining the sheet Ia pending picking up by the arm 11.

All the belts are wound endlessly around associated pulleys 3, some of which are idle and some motor-driven so as to produce the one-way outward and return travel of the belts; the actuation of the conveyors is per se conventional and consequently not described in detail . Advantageously the belts 121 and 122 of the device 100 have a front part higher than the rear part so as to obtain an improvement in selection of the sheets and a distance from the ground of the loading seat 130 within the reach of an operator of average height who must position a new stack of sheets Ia inside the said seat 130. The conveyor belt 221 is hinged in 202 with the device 100 and has parts 10b resting against corresponding surfaces of the sheet insertion/removal device 10a for producing an inclination with a front part lower than the rear part . Advantageously, both the devices 100 and 200 are joined together and mounted on wheels 101 for allowing easy movement towards/away from the sheet insertion/removal device 10a in turn mounted on wheels 201; in the example shown it is also envisaged that the second storage device 300 is joined to the carriage of the sheet insertion/removal device 10a.

Said devices 110 for selecting the sheet (Fig. 2) envisage a plurality of plates 111 which are mounted on support bars 112 with respect to which they may be displaced/rotated so as to vary the distance from the pick-up belts 121 depending on the thickness of the

sheets Ia to be removed and on which they may be fixed, by means of locking means Ilia, for example of the screw-type, with adjustable interaxial distances, depending on the transverse dimensions of the sheet Ia. As shown (Figs. 2, 3) it is also envisaged that the conveyor belts 121,122 and 221 may be controlled independently so as to allow picking up and feeding of several small -size sheets arranged alongside each other along the path in the longitudinal direction. Owing to the independence of the conveyor belts it is also possible to rectify, without damage, any non- alignment of the sheets Ia when leaving the respective stack 1. The unloading device 300 comprises conveying means 320 formed by a first conveyor belt 321, with pushers not shown, for picking up a stack of finished sheets Ib, carried by the extraction arm 12 into a storage zone 330 where they are retained by a stop 331, and means 322 for conveying said stack of sheets Ib to the exit/removal zone for the subsequent working steps (not shown) .

With the structure described, the cycle sequence is as follows :

- the apparatus is arranged in the vicinity of the machine 10;

- the partitions 131 are adjusted and the means 110 for selecting the sheets Ia in the loading seat 130 are adjusted according to the dimensions of the sheets Ia to be processed; - the first stack of sheets Ia is inserted inside the respective seat 130;

- the apparatus is started so that:

- the pick-up belts 121 cause feeding of the first sheet Ia from the bottom of the stack 1; - the extracted sheet Ia is fed towards the belts 122

and from the latter to the conveying devices 200 as far as the zone 230 for picking up by the arm 11;

- once processing in the machine has finished, the sheet is extracted by the arm 12 and deposited in the zone for storing the finished sheets Ib;

- from here the stack of finished sheets is removed by the belts 321 and 322 provided with special pushers (not shown) , enabled in a controlled sequence for expulsion of the stack. The entire operating sequence is controlled by corresponding programming, actuating and control means 1000 associated with detection and signalling means, not shown nor described in detail . It is therefore clear how the apparatus according to the invention allows the feeding/unloading of stacks of sheets la/lb to be processed/finished into/from pressing machines/platens in a continuous manner, resulting in a significant reduction in the machine downtime due to the need to stop the said machine in order to feed successive stacks of sheets to be processed, said feeding in the known art occurring discontinuousIy .