The present invention relates to an apparatus for the high speed stacking of paper sheets or forms. Such a stacking is effected by the apparatus according to the invention both by accordion-like folding a continuous band along portions thereof at predetermined spacings and, alternatively,by simply superimposing separate sheets. Such an apparatus finds particular application both in the preparation of paper for high speed printers, such as laser printers and the like, in form of a continuous band accordion- like folded to form packages containing a predetermined number of loops or "forms" connected to each other by prepunched cross lines, and in the superimposition, still accordion-like, of said forms coming out of the printer or by simple superimposition thereof after their separation by a tearing action along the afore said prepunched lines of the band.

Apparatus are already known by which the problem of the high speed stacking of paper sheets or forms , such as for example those being the subject of the European Patent Application EP-A-368,392, and of EP-A-412,437,in the name of the same Applicant, to which reference shall be made in the description of the apparatus of the present invention.

It has been observed that the apparatus according to the above European applications, although being fully reliable to carry out their duty, sometimes raised operating difficulties with specific reference to the tearing separation of the band both for the carrying out of the separation per se, and for the reason that such a separation gives place to strains of not negligible value which may induce negative effects on the devices positioned at the inlet of the apparatus for the control of the band advancement in the apparatus.

It has been furthermore seen that the flexibility of these apparatus was limited by the fact that they were difficultly useful for the stacking of single forms, namely of the forms coming out of the printer as a continuous band and separated from each other for example by tearing.

The stacking of forms separated from each other is not a simple operation mainly because, contrarily to the case of the continuous band for which no particular problems exist in order to "direct" portions thereof towards stopping and/or folding stations for the edges of said portions since the band is a continuous assembly, these problems exist and are important in the case of separate forms both in terms of their guidance and of their proper orientation.

SUBSTITUTE SHEET

It has been also found that the afore said apparatus, as a consequence of the number of operating parts of which they are composed, were of rather cumbersome construction also owing to the necessity of providing more than one control motor for their operation. Moreover the presence of more than one control motor causes the probabilities of intervention request for the machine maintenance to be increased. The purpose of the present invention is that of providing an apparatus by which the above mentioned problems are solved in an advantageous, very simple and reliable manner.

A more specific even if non exclusive purpose of the present invention is that of providing a device for the tearing separation useful in an apparatus of the above mentioned type.

A further purpose of the present invention is that of providing an apparatus of extremely simplified construction and of particularly reduced size for the high speed stacking of sheets or forms both by accordion-like folding of a continuous band and by superimposing separate sheets, which is fed with a continuous band and comprises dragging means therefor towards diverting or deviating means of its portions suitably spaced or of the initial edge of said sheets towards either a first or a second stopping and/or folding stations positioned at two opposite sides of a sheet stacking plane, band guide means being provided between the band inlet area to the apparatus and said deviating means, said guide means being associated to means actuatable for carrying out the tearing separation of said band along a prepunched cross line thereof, comprising two pairs of respectively upper and lower rollers adapted to get into friction contact with the said band, the aforesaid deviating means comprising nozzle means connected to an air pressure source, said nozzle means being suitable for emitting an air blow essentially orthogonally directed with respect to the plane of the paper sheet coming out from the said guide means and downstream of said tearing separation means, said apparatus being characterized in that either roller of the pair of upper rollers is provided with at least a planar bevelled portion and by the fact that the lower rollers are essentially cylindrical, at least one of them being permanently driven into rotation with a peripheral speed higher than that of the upper rollers, said lower rollers being spaced from each other in the rest condition when said bevelled portion of the upper roller is parallely positioned in front of the plane of the paper band in the rest condition of the afore said roller

and being into friction contact with the band in the operating condition, between said upper and lower roller pressing means being positioned which are displaced from a retired or rest position in which are detached from the said band when the upper and lower rollers are in the rest condition to an operating position in which are engaged therewith during its tearing phase, said sheet stacking plane being provided with ejcting means for the sheet packages and with sensing means detecting their presence onto said plane.

The features and advantages of the apparatus according to the present invention shall appear more clearly from the following detailed description of a non limiting embodiment thereof, the description being made with reference to the accompanying figures in which: fig.l is a schematic perspective view, with portions partially omitted, of the apparatus according to the invention as a whole; figs.2 and 2a are schematic side elevation views of the apparatus of fig.l in two operating conditions; fig.3 is a schematic view according to the lines III-III of fig.l of one of the side stopping stations at the beginning of the forming of the sheet package; fig.4 i a partial view according to the direction of the arrow IV of fig.l of the afore said station; fig.5 is a very simplified representation of the tearing separation device, taken alone, according to the lines V-V of fig.l in the rest condition; fig.6 is a representation like fig.5 of the said device according to the lines V-V of fig.l at the beginning of the sheet tensioning; fig.7 is a view like fig.5 still according to the lines V-V of fig.5 showing the tearing phase; fig.8 is a schematic plan view of the upper rollers of the tearing separation device; fig.9 is a schematic plan view of the lower rollers of the tearing separation device; fig.10 is a cross section view of one of the upper rollers; fig.11 is a partial view from above of one of the upper rollers; fig.12 is a plan view detailedly showing the sheet stacking plane; fig.13 is a side view of the aforesaid stacking plane.

With particular reference to figs.l and 2, the apparatus according to the present invention comprises a fixed framework 10 onto which the means for the stacking of

paper sheets are placed, these sheets being either in form of continuous band and separated from each other.

In the present disclosure, only by way of example, reference shall be made to the case of the stacking of separate sheets since the same considerations hold true for the stacking of sheets in form of continuous band.

It is anyhow to be noticed that the apparatus is fed at the inlet thereof in both cases with a continuous paper band. It arrives according to the direction of the arrow A of fig.2 for instance from a printer not shown.

At the inlet of the apparatus there are provided dragging means for the band 12 consisting, in the embodiment under consideration, of a pair of known "tractors" 2, one for each perforated side edge of the band 12. Only one of them is viewable and represented in fig.2, the other being identical. Both tractors comprise a pair of gears 23,25, connected to each other by a toothed belt 27 and secured by keying to shafts 29,31,rotatably supported by the framework 10. One of the gears 23 is connected, by means of a non represented ratchet device provided at the end of the shaft 31 associated to the same gear 25 and of a transmission gearing comprising toothed belts and toothed pulleys 25a,25b, to the only one control motor of the apparatus, indicated by the reference 33. The advancement of the tractors 22 is thus unidirectional. At the end of the shaft 31 opposite to that bearing the above mentioned ratchet device, a sensing device is provided for detecting the angular position of said shaft 29, such as an "encoder" or the like (not shown), thus adapted to provide a signal corresponding to the position of the shaft 31 and thus of the band 12 and particularly of the prepunched lines thereof. This information is very useful for the sequence activation of the several operating parts of the apparatus. Still at the inlet of the apparatus two guide profiles 14 and 16 (fig.2) are provided and fastened in a known manner to the framework 10, owing to which the band 12 is deviated downwardly thus advancing according to an essentially vertical direction. The length of both profiles 14 and 16 is equal to the maximum width possible for the band 12 feeding the apparatus.

More particularly the lower profile 14 has a half a circle shape, whereas the upper one has a first essentially planar length 16a which is downwardly inclined and is extended by a second length 16b having the shape of a circle arc. Below the profiles 14,16 a first and a second plurality of essentially rectilinear guide

strips 18,20, which are connected in a whatsoever known manner (not shown) to the framework 10. The strips are oppositely positioned and parallel in pairs abd the spacing between the strips of one series and those of the other series as well as that between the strips of each series and lastly their width are predetermined as hereinafter clarified.

The upper end of each rod 18,20 is outwardly bent so as to form a substantially funnel-like structure forming an invitation for introduction of the band 12 between said strips.

The strips 18,20 are associated to means for carrying out the tearing of the band 12 along prepunched cross lines thereof and these means are actuated or not depending on whether the apparatus operates with separate forms or with continuous band. These means shall be described hereinafter with reference to the fig. 5 to 11. As above stated the strips 18,20 are of a predetermined width and are suitably spaced. In this manner the strips can be positione so that they pass through grooved parts 24b, 26b of the rollers 24, 26 forming the means for the sheet tearing separation means, hereinafter described, thus being very close to each other and thus being a valid guide especially in the case of the processing of separate forms which might be displaced from the correct advancing direction just owing to the effect of the means foreseen for directing their fore edge towards one of the stopping stations, these means applying thereon a displacing action cross-wise directed with respect to the said advancing direction.

The afore said means for the tearing separation of the forms comprise one pair of upper grooved rollers 24 and one pair of lower grooved rollers 26. The upper rollers 24 are essentially parallel to each other and one of them has a planar bevelled portion 24a (figs.8, 10 and 11). In this manner, when said rollers 24 are positioned with the bevelled portion 24a parallelly facing the plane of the band 12, a passage is defined for the said band which remains free for a short time, anyhow sufficient to permit possible strains to be relieved and possible ondulations to be eliminated. These strains and ondulations, as a matter of fact, occur rather often in a band coming out from a printer, particularly a laser printer.

The lower rollers 26, although being essentially parallel to each other, are arranged so as to take two different positions with respect to each other respectively of resting, in which are spaced from each other, and of operation, in which are

brought into friction contact with the band 12 to carry out the tearing separation of one form.

At least one of the two rollers 26, particularly that of the right side looking the figures 1 and 2, is permanently driven into rotation, and to this end it is connected to the control motor 33 through a known kinematic transmission, partially viewable in fig.2, for example comprising toothed pulleys and chains 26c, 26d. The said roller

26 is supported in a whatever known manner by the framework 10 of the apparatus and is driven only in rotation whereby it cannot be displaced.

The second roller 26, particularly that of the left side in figs.l and 2, is supported at the ends in a freely rotatable manner by a pair of shaped arms 126 pivotally connected at 127 to the framework 10 of the apparatus.

In this way said roller 26 can be displaced between the two positions corresponding to the resting and to the operation as above mentioned and represented in the figs.2 and 2a. With particular reference to the figs.5, 6 and 7 the resting position (with the rollers 26 soaced from each other) is taken when the planar bevelled portion 24a is facing the plane of the band 12 (fig.5) as above stated, whereas the operating condition (with friction contact of the rollers 26 with the band 12) is taken when the rollers 24 are driven into rotation so that their curved surface portions come into friction contact with the said band 12 (figs.6 and 7). In the above mentioned operating condition the band 12 has one prepunched line P thereof located in an intermediate position (fig.6) between the two pairs of rollers 24, 26.

The rollers of each pair rotate in opposite directions with respect to each other as indicated by the arrows M and N of fig.6 and their rotation direction is thus such that a pulling action is applied to portion of band being between the aforesaid rollers to effect the tearing of the said portion along its prepunched cross line P.

The tearing phase is illustrated in fig.7.

The diplacement of the movable roller 26 can be effected, for example, through a friction control unit adapted to rotate the arms 126 so as to bring the rollers 26 into contact with the band 12.

When the friction unit or clutch is disengaged, the arms 126 are returned to the initial position by elastic means.

According to a further feature of the apparatus according to the present invention, and with particular reference to fig.2 and to the figs, from 5 to 7, between the

upper rollers 24 and the lower rollers 26 pressing means are provided, indicated as a whole by the reference number 72, which are also capable of taking a resting position in which are detached from the band 12, and of being brought to an operating position in which said means become engaged with the said band. Such a movement according to the invention takes place synchronously with that of the rollers 24 and 26 from the resting condition to the operating one. More particularly the displacement of the pressing means 72, in the embodiment under consideration, takes place since they are associated to the lower displaceable roller 26. More precisely the said pressing means 72 are essentially formed by a shaft 74, supported by the arms 126, to the said shaft 74 a number of small rollers (76) being mounted, these small rollers (76) being idle and prevented, in a whatsoever known manner, from longitudinally sliding along the shaft 74.

As it is particularly seen from fig.6, when the small rollers 76 are brought into engagement with the band 12, the latter takes a deformed shape represented by a dashed line in the above mentioned figure owing to to pulling action applied by the pressing means 72. Preferably the small rollers 76 are brought into engagement with the prepunched line P of the band 12. Inthis manner, thanks to te above said pressure action and to engagement with the said area, said pressing means 72 are capable of absorbing most of the strains to which the band 12 is subjected during the tearing phase.

That is particularly advantageous since these strains are rather relevant and might be transmitted to the tractors 22, since the possibility exists that, during the tearing, the band 12 is abruptly slipped forwardly despite the friction engament with the rollers 24, whereby the operation of the tractors 22 might be affected.

With particular reference to figs.l and 2. an essentially vertical bar 44 serves as the side abutment for the sheet package, not shown, which shall be formed onto the horizontale receiving plane 46, said abutment being indicated as a whole by the reference number 48.The function of the abutment 48 is that of keeping vertically aligned the stacked sheets, the side edge of which is engaged with the said abutment. In the embodiment under consideration in this description the abutment 48 is like that being the subject of the European Patent Application No.91200830.7, in the name of the same Applicant to which reference is made for the understanding of the structure of the abutment 48.

For sake of completeness only it is herein recalled that the abutment 48 and, more particularly, the cylindrical body 50 in which the bar 44 is housed, is vertically movable with respect to the said bar and cross-wise together therewith. The latter movement is particularly permitted thanks to the connection between the bar 44 and the related supporting means consisting of a L-shaped bracket indicated as a whole by the reference number 52, which is displaceable along a rotatable threaded shaft

54 and along a fixed smooth bar 56.

Like abutment means, herein not represented, are provided at the opposite side of the sheets to be stacked, apart from the fact that the latter, contrarily to the preceeding one, is fixed in the cross-wise direction and displaceable in the vertical direction as described in the above mentioned patent application

In order to direct the sheets to be stacked onto the plane 46, after the tearing separation when a continuous and cross-wise prepunched paper band is fed to the apparatus, nozzles 30 are provided connected through a shaped duct 32 to a header

34 for the compressed air supply, said header being in turn connected, under the control of a controllable a programmable check valve, to a source of air under pressure.

Both the check valve and the air pressure source are not represented and are of standard type.

Of course along the header 34 a number of shaped ducts 32 is provided, seated in the grooves 26b or in separation spaces dividing the single cylinders forming each roller 26.

It is to be observed that, even if not shown in fig.2 for sake of clarity of the drawing, a like header is symmetrically provided, as well as the shaped ducts 32 and the nozzles 30, whereby against the paper sheet coming out of the guide hollow space defined by the strips or strips 18 and 20 a number of air blows impinges from either side dependint on the actuation and thus on the programming of the check valves.

As a consequnce the fore edge of the paper sheet is tangentially bent owing to the action of the said number of air blows and the sheet is laid down onto the plane 46 with the desired laying and orientation.

As a matter of fact, especially when a tearing separation is effected before the laying down and the collecting onto the plane 46, the air pressure blows coming out

of the nozzles 30 fulfill a double function.

Firstly, upon the tearing separation is carried out, they cooperate so as to enhance the complete coming out of the sheet below the prepunched line along which the tearing separation has been carried out.

A second actuatation of these nozzles, immediately after the first one, is used to direct the first incoming sheet so as to lay down it onto the plane 46 with the desired laying.

The above mentioned stopping and/or folding stations are schematically illustrated in figs.l and 2, and part thereof is schematically represented in an enlarged scale in the figs.3 and 4. Of these stations, that of the right side looking at the figures 1 and 2, is indicated as a whole by the reference 62, whereas that of the left side in the same figures is indicated on the whole by 64.

The above said stations essentially comprise a grooved roller 66,68 (figs.l and 2) rotating in the opposite direction with respect to the other one and which, in the case of processing of a continuous band 12 does also carry out the folding of the band portion with which it is engaged, whereas in the case in which separate sheets are processed keeps the fore edge of said sheets against the collecting plane 46. The stopping means of the aforesaid stations consist of retractable appendices 70, only one of which is represented in fig.l for sake of representation clarity, against which the band or sheet to be stacked is stopped. The lower end of the retractable appendices 70 is always maintained into contact with the collecting plane 46 as the latter is lowered with the incresed height of the sheet package being formed thereonto.

Referring now particularly to the figures 12 and 13 the stacking plane 46 shall be detailedly described which, starting from a raised position at the beginning of the forming of the form package, is gradually lowered in a known manner (not shown) as the sheet package is formed.

Said plane 46 is provided according to the invention with means for the ejection of the completed sheet package from the apparatus.

The ejection can be effected by firstly sending a stopping signal to the plane lowering means as well as a substantially simultaneous signal for the actuation of the ejecting means.This operation can be effected when the consistency of the sheet package is believed adequate, whereas the signals can be emitted under the control

of suitable proga ming means, per se known and not represented. The ejecting means comprise three belts, essentially parallel to each other and cross-wise extending with respect to the stacking plane 46 and thus to the direction according to which the forms are laid down onto the said plane. In the embodiment under consideration, the two side belts 78 of the three belts are toothed in order to ensure a contact without slipping with the sheet package, whereas the central one 80 is devoid of teeth.

T ie belts 7& and 80 are particularly of the endless type and encompass the plane 46. Their motion is ensured by being engaged with belts 178, 180, (which are toothed for the belts 78 but not for the belt 80), said pulleys being keyed onto a shaft 190 seated in a cavity formed on the two opposite sides 82 of the plane 46 and freely rotatable. The rotation of the shaft 190 is obtained by connecting said shaft to motor means not shown and under the control of the above mentioned programming means. The stacking plane 46 is lastly provided with sensing means for the detection of the presence of the sheet package which, in the considered embodiment, as shown particularly in the figs.12 and 13 consists of an electrical photocell 84 located on the upper surface of the plane 46 at the edge 82 through which the sheet package is ejected. The apparatus is operated, thus stacking the sheets one onto another, until the cell 84 is covered by the sheet package. Upon the package has reached the desired consistency, the apparatus is stopped and the package is ejected as more particularly explained hereinabove, particularly by the advancing motion of the belts 78, 80. If the package is correcly ejected, i.e. is comes completely out of the apparatus, the cell 84 is uncovered and a novel operation cycle of the apparatus is started.

In the case that the package does not come completely out of the apparatus, the cell84 remains covered and the apparatus is not started again, lacking the necessary activating signal to its operating members. The attendant is then allowed to manually take out the sheet package, whereby the cell 84 becomes uncovered and the apparatus is permitted to start again its operation.

The operation of the apparatus according to the invention, apart from that of the tearing separation device already shortly described hereinabove, is the following one: The band 12 is fed to the apparatus and advanced by the tractors 22. Upon having been deviated downwardly by the profiles 14, 16, it advances to the tearing means

24, 26, which can be either operated or not.The position of the abutment 48 has been preliminarily adjusted as a function of the width of the band 12.

In this advancement phase the aforesaid band is guided by the strips 18, 20 passing through the grooves of the rollers 24, 26. If the tearing separation device 24, 26 has been operated, when the fore edge 12a of the sheet starts protruding in a substantial measure below the tearing separation device the compressed air blows are actuated being emitted through the nozzles 30 (of course from the suitable side to oblige the paper sheet to be bent towards the desired side).

The emission of an instantaneous blow or for a very short time, since the continuing advancement downwardly of the sheet causes the sheet to take the desired laying i.e. since the edge has taken a loop shape of a lenght such that, the advancement speed of the sheet being the same, it is permitted to reach the stopping station 62. At that point, as already stated, the blow emission is ceased whereby the sheet can be laid down by gravity and owing to its intrinsic elasticity it takes the desired position onto the collecting plane 46.

This operation is cyclically repeated for ecach subsequent sheet until the desired number of sheets is stacked.

Of course the sequence of the several operating phases shall be controlled and adjusted by means of suitable programming means, per se known and thus not represented.

The advantages which can be obtained with the apparatus of the present invention are evident from the above description and the main one have been already recalled hereinabove.

Variations and modifications conceptually equivalent can be made in the apparatus of the invention without falling out of the scope thereof.