Apparatus for the high speed piling up of paper sheets or continuous band with, tearing separation along preperforation lines

Abstract: An apparatus for high speed stacking paper sheets by either accordion-like folding a continuous web or superimposing separated sheets. The apparatus is provided with drive means associated to tearing means thereof along its prepierced lines. Diverting means for properly spaced portions of either the continuous web or the leading edge of every sheet to a first or a second stopping and/or folding station arranged on both opposed sides of the sheet stacking plane are further provided. Said diverting means comprise, on each side of the sheets to be stacked, a plurality of compressed air blowing nozzles (30), connected with a compressed air source so that said continuous web portion or the leading edge of the said sheet is directed to the predetermined stopping and/or folding station. The apparatus further comprises tear separating means comprising two parallel and superimposed rollers (24,26) formed everyone by a plurality of cylinders, of which at least the lower cylinders are provided with at least a planar or bevelled portion, so that when the bevellings are facing each other faced the web freely travels, whereas it becomes engaged in the different situation.

Description: The present invention regards an apparatus for high speed stacking of paper sheets or forms. Said stacking is provided by the apparatus according to the invention by either accordion-like folding of a continouos web along preset spacing portions thereof or, alternatively, by simple superimposition of separated sheets. Such an apparatus is particularly useful both in preparing paper for high speed printers, such as laser printers or the like, as a continuous accordion folded web to provide packeges containing a preset number of loops or "forms" connected to each other by transversal prepierced lines, and in the superimposition of said forms coming out from the printer, after that they have been each other separated by a tear action along the above mentioned prepierced lines. More specifically, the present invention pertains to the apparatus to effect a tear separation along prepiercing lines preset in the continuous web and defining the single forms or sheets. Devices for providing this tear separation are already known and as an example, it is possible to mention the device covered by the utility model Italian patent No. 215262 filed on november 21 1988. Devices advantageously solving the problem of providing a continuous accordion-like foled web are already know, as for example that which was the subject matter of EP-A-368392. US-A-4 131 272 discloses an apparatus for stacking of paper continuous band in form of exact sount accordion like folded stacks, comprising tear separation means cooperating with web guide means so as to burst the web at a predetermined point prior to folding rollers. US-A-4 460 350 discloses a stacking device for a continuous printed paper web, wherein air jets impinge at discrete positions on a top surface of the paper sheet being laid down in an accordion like folded stack. It has been noticed that the devices of the above applications and patents, although are completely reliable for doing the them entrusted duty, sometime had some working problems for what regarded the tear separation and the means provided to direct the continuous web portions to one or the other of the stopping and/or fending stations of the end edges of said portions. Further it has been noticed that the versatility of said devices was limited by the fact that hardly they could be used for stacking loose forms i. e. forms coming out from the printer as a continuous web and each other separated for example by tear separation. The stacking of the forms separated from each other is not certainly an operation which can be carried out easily because, differently from the continuous web for which there are not specific problems in directing the portions thereof to the stopping and/or folding stations, as the above mentioned web is a continuous piece, said problems are relevant in the case of separated forms either in driving or suitably directing them. It is an object of the present invention to provide an apparatus which can solve the above mentioned problems in an advantageous, simple and reliable way. It is a more specific object of the present invention to provide a tear separating device useful in a device of the above mentioned kind. The main object of the present invention is met by a high speed stacking apparatus according to claim 1. In turn, the tear separating device according to the invention in its most general embodiment comprises: a first cylindrical roller pair facing each other faced and in frictional contact with said sheet, every roller rotating around its own axis at a constant peripheral speed and in contrary directions for driving the paper web along a preset path; a second cylindrical roller pair, everyone of them being provided with a planar bevel, said bevels facing each other and being spaced with respect to said sheet and having a substantially equal extension, said second pair being arranged downstream with respect to said first pair; the rollers of said second pair being rotatable on command around their own axes and in contrary directions to carry out at least a complete turn with peripheral speed higher than that of said first pair, said rollers getting in frictional contact with said paper web, in which at least a roller of said second pair comprises a series of cylinders spaced from each and aligned along their axes said cylinder series comprising at least a central cylinder and lateral cylinders, the central cylinders being staggered in advanced phase with respect to the lateral cylinders, so that said central cylinders get early in frictional touch with said sheet with respect to the lateral cylinders. According to an embodiment variation of the tear separation device useful in the apparatus according to the invention also the rollers of the first pair are provided with the bevels or millings above defined for said second roller pair, without having the already mentioned phase staggering feature of the central cylinders with respect to the lateral ones. According to another preferred embodiment of this variation, the rollers of the second roller pair have a cross-section larger than that of said first pair. According to a further embodiment of this variation the upstream arranged pair of friction advancement rollers of the paper web is omitted and the rollers of said first pair are moved by a continuous rotation movement. The features and the advantages of the apparatus according to the present invention will result more clearly from the following detailed not limiting specification, which will be made with reference to the enclosed figures of which: the Figure 1 is a perspective schematical assembly view, with partial breakings, of the apparatus according to the present invention; the Figure 2 is a schematical view in side elevation of the apparatus of Figure 1; the Figure 3 is a schematical view according to the section III-III of Figure 1 of one of the lateral stopping stations at the beginning of the formation of the sheet package; the Figure 4 is a partial view according to the direction of the arrow IV of Figure 1 of the above mentioned station; the Figure 5 is a schematical view of the whole tear separating device according to a first embodiment; the Figure 6 is a view, partially in cross-section, along the line VI-VI of Figure 5; the Figure 7 is an assonometrical depiction of a roller of the second pair; the Figure 8 is a perspective, schematic, partial view of an embodiment variation of the tear separation device; the Figure 9 is a schematic view of the apparatus according to the cross-section IX-IX of Figure 8 in rest condition; the Figure 10 is a schematical view of the apparatus according to the same cross-section and at the beginning of the sheet tensioning; the Figure 11 is a schematical view of the apparatus depicting the tear phase. Particularly referring to Figures 1 and 2, the apparatus according to the present invention comprises a fixed frame 10 on which the means are arranged for stacking paper sheets in form of either a continuous web or sheets separated from each other. In the present specification, just on exemplifying way, more specific reference will be made to the stacking of separated sheets, as the same considerations will be valid for the stacking of sheets as a continuous web. It is however to be noticed that the apparatus is fed at the inlet end for both cases with a continuous paper web 12. This web comes, according to the direction of the arrow A in figure 2, for example from a printer (not depicted). At the inlet of the apparatus there are arranged two essentially semicircular and concentric section bars 14 and 16 (figure 2) fastened in a known way to the frame 10, by means of which the web 12 is down wardly diverted, thus advancing according to a substantially vertical direction. The length of both the section bars 14 and 16 is equal to the largest possible width of by the web 12 feeding the apparatus. Under the section bars 14, 16 are arranged a first and a second plurality of essentially rectilinear rods 18, 20 of equal length and arranged at the same height. They are fastened in any known way, not depicted, to the frame 10, are opposed and parallel by pairs and the spacing between the rods of a series and those of the other one, as well as their width, are predetermined, as it will herebelow explained. The upper end of each rod 18, 20 is outwordly bent in order to form a substantially funnel shaped structure providing an invitation for inserting the web 12 between said rods. The advancement of the web 12 is caused by a pair of grooved tractor rollers 22 between which the above mentioned web is passed, said cylinders being pivotably supported by the frame 10 and connected to not shown motor means. Under the tractor rollers 22 means are arranged to effect the tearing of the web 12 along the prepierced lines and said means are either actuated or not according depending on whether it is desired to operate either on separated forms or on a continuous web. These means will be herebelow described having reference to figures 5-11. As above mentioned, the rods 18, 20 are of predetermined width and properly spaced. That allows to arrange said rods in order to pass trough the grooved portions of the cylinders 22, 24 and 26 resulting therefore very closed to each other and thus being a valid guide particularly in the case of operating on separated forms which could be moved from the proper advancing direction just by the operation of the means intended to direct their fore leading edge to one of the stopping stations, said means causing a displacement crosswise directed with respect to said advancing direction. With particular reference to figures 1 and 2, an essentially vertical side abutment of the sheet package, not depicted, which will be formed on the horizontal stacking plane 46, maintains vertically aligned the stacked sheets, the side edge of which engages the above mentioned abutment. To direct the sheets to be stacked onto the plane 46, after the tear separation when a continuous and transversally prepierced paper web is fed, there are provided nozzles 30 connected through a shaped duct 32 to a manifold 34 feeding compressed air, which in turn is connected, under the control of a controllable and programmable on-off valve, to a pressurized air source. Both the on-off valve and the pressurized air source are not depicted and are of conventional type. Of course, along the manifold 34 a plurality of shaped ducts 32 is provided housed in the hollow spaces separating the single cylinders forming each roller 26. It is to be noted that, even if not shown in figure 2 for sake of drawing clarity a like manifold 36 is simmetrically provided, as well as the shaped duct 32 and the nozzle 30, so that the paper sheet coming out from the guide gap defined by the rods 18 and 20 is struck by a plurality of air blows on either depending on the control and thus on the programming of the on-off valves. Consequentely, the fore leading edge of the sheet is tangentially bent by the above mentioned blow plurality and the sheet is deposited onto the plane 46 with the desired laying and orientation. As a matter of fact specifically when a tear separation is effected before the deposition and stacking onto the plane 46, the compressed air blows emitteed by the nozzles 30 provide a double function. First, once a tear separation is effected, they cooperate so as to to help the complete coming out of the sheet under the perpierced line along which the tear separation has been effected. A second immediately subsequent actuation of the blows themselves serves to direct the first coming sheet in order to deposite it onto the plane 46 with the desired laying. The above mentioned stopping stations are schematically depicted in the figures 1 and 2 and a portion thereof is schematically depicted in enlarged scale in the figures 3 and 4. Of said stations the right one in the figures 1 and 2 is indicated as a whole by the numeral 62, while the left one of the same figures is indicated as a whole by the numeral 64. Substantially the above mentioned stations comprise a grooved roller 66, 68 (figure 1) rotating in substantially opposed direction with respect to the other and which, in the case a continuous web 12 is treated, also provides the folding of the web portion with which is engaged, while in the case of operation on separated sheets maintains the fore edge of said sheet against the collecting plane 46. The stopping means of the above mentioned stations consist of retractable fingers 70, only one of which is depicted in figure 1 for reasons of depiction clarity, against which the web or the sheet to be stacked stops. The lower end of the retractable fingers 70 is always getting in touch with the collecting plane 46 as this latter descends as the height of the sheet packages being formed thereon increases. Referring now to figures 5 and 6, it is noticed that the device 110 comprises a tractor 111 for the sheet 112 coming, for example, from the laser printer (not shown). Said tractor consists of driving pulley 113 and a driven pulley 114 connected to each other by a toothed belt 115. The driving pulley 113 is moved by a synchronous electric motor or the like (not shown) to drive in rotation the belt 115 according to the arrow F₁ for advancing the sheet 112 to the snub pulley 116 and a first cylindrical roller pair 117, 118. The cylindrical rollers 117, 118 are rotated around their own axes as indicated by the arrows F₂, F₃ by means of an electric synchronous motor 119 to which they are connected through pulleys 120, 121, a toothed belt 122 and gears 123, 124 (figure 6). The external surfaces of said rollers are in frictional contact with the paper sheet 112 and have a preset and constant peripheral speed ensuring a little tension of the sheet 112 in the zone between the tractor 111 and the cylindrical rollers 117, 118 in order to avoid undue ripples of said sheet 112. Downstream with respect to the first cylindrical roller pair 117, 118 there is a second roller pair 125, 126, each of which is provided with a planar bevel 127, 128, being each bevel substantially facing the other and being spaced with respect the paper sheet 112, so that when the rollers are stopped in the indicated position, the sheet 112 can freely pass between them to continue the motion to a collecting plane (not shown) as indicated by the arrow F₄. The bevelled rollers 125, 126 can rotate on command around their own axes in opposed directions, as indicated by the arrows F₅, F₆, to make at least one complete turn with a peripheral speed higher than that of the cylindrical rollers 117, 118 so that the surfaces of the cilinders 125, 126 beyond the bevels come in frictional, temporary contact with said paper sheet 112 causing a substantial tensioning on the sheet 112 high enough to produce a tearing at the transversal prepierced straight line in the lenght of the sheet 112 comprised between the first and the second cylinder pairs. The rotation of the bevelled rollers 125, 126 is controlled by an assembly 129 comprising an electric motor and a clutch (not shown) by means of pulleys 130, 131, toothed belt 132 and gears (not shown) of the kind suited for rotating the cylinders 117, 118. In the zone comprised between the cylindrical rollers 117, 118 and the bevelled rollers a pliers mechanism 133,134 can been interposed for blocking the sheet 112 in a determined position for a very short time in order to have the tear of the sheet 112 effected along the prepierced straight line which will be located in the lenght comprised between said pliers 133, 134 and the pair of bevelled rollers 125, 126. It is clear that lacking the pliers 133, 134 the device operates continuously and it is essential that the peripheral speed of the bevelled rollers 125, 126 be higher than that of the cylindrical rollers 117, 118 while in the presence of said pliers 133, 134 the device operates discontinuously and the peripheral speed of the rollers 125, 126 must not be necessarily related to the peripheral speed of the cylindrical rollers 117, 118, since the latter are not cooperating to the tear function, but carrying out a tensioning operation on the sheet 112 in the lenght comprised between the tractor 111 and said rollers 117, 118. As it will be noticed in figure 5, on an edge of the sheet 112 preferably a "mark" 135 is impressed, usually a black not reflecting rectangle, or also of some other kind, located at a preset spacing from the preceeding weakening transversal straight line of the sheet 112; on said "mark" a detector 136 is located which in the case of a not reflecting "mark" can be a reflection photoelectric device receiving a signal at the passage of said "mark" and a different signal when the "mark" is away. The detector 136 is electrically connected to an operating unit 137 to which it sends signals corresponding to those received, said operating unit consistently controlling respectively the synchronous motor 119 and the electric motor-clutch assembly 129 for moving the first roller pair 117, 118 and the second roller pair 125, 126 (in the case the pliers 133, 134 are lacking); on a contrary case, in the presence of said pliers 133,134, the operating unit further controls the movement of the pliers themselves and the corresponding temporary stopping of the tractor 111. Looking more in detail at the bevelled roller 126 and referring to the figure 7, it is to be noticed that the roller is divided in a series of cylinders 126' spaced from each other and aligned along its axis or shaft 140. Said cylinders 126' comprise lateral cylinders 141, 142, 143, 144 and central cylinders 145 and 146. While the lateral cylinders have the bevel 128 oriented according to the vertical line "b" substantially parallel to the paper sheet 112 passing between the two rollers 125, 126 of the figure 1, the cylinders 145, 146 of equal size have their own bevel 128' stagged in advance by an angle "a". The same features are found on the opposed roller 125. In the configuration here above described and depicted in figure 7, it is easy to understand that the central cylinders 145, 146 of the roller 126 upon rotating around the axis 140 will come in touch with the opposed cylinders of the roller 125 in advance with respect to the lateral cylinders 141, 142, 143, 144 of the roller 126 with the opposed cylinders of the roller 125. In such a way a tension strain will be provided firstly on the paper sheet 112 at the central area and subsequentely at the lateral areas. Thus the tear beginning of the tear of the sheet 112 will occur in the central area thereof, then extending to the lateral areas. Suitably the advance staggering angle "a" of the central cylinders 145, 146 is not less than 5° and preferably is comprised between 5° and 10°. With an angle less than 5° there are not appreciable results because the tearing might begin also laterally depending on the weakening variability along the transversal straight line, on the position variability with respect to the tear rollers, on the kind of paper being used and on other possible practical troubles. With an angle "a" more than 10° a possibly excessive impact differential might occur in the central area, so that the tear begun in the central area would propagate in the lateral areas in a not enough harmonic way with troubles for the tear itself. Referring to figures 8-11, a further variation of the tear separation device is shown. In this connection, as well as in connection with the figures 5, 6 and 7, it is to be emphasizer that the representations provided in the figures 5 and 8 are highly simplified with respect to that of figure 1 and different reference numerals have been provided to avoid confusion. As shown in the figure 8, the separation tear device comprises two pairs of counterrotating rollers 210,212 as indicated by the arrows F and G, each consisting of a plurality of cylinders 214,216 opposed to each other mounted to or formed in shafts 218, 220 rotatable on a fixed support frame 222. At the ends of the shafts 218, 220 gears 224,226 are mounted which are driven into rotation by a toothed belt 228 which is connected by just one driving motor 230 engaging a gear 232 fastened on the shaft thereof. The numeral 234 indicates a transmission gear which is locked in a position which can be changed on the frame 222 to maintain in tension the tooted belt 228. As the diameters of the gears 224 and 226 are equal, the rotation speed of the shafts 218 and 220 will be the same. Referring now also to figures 9 to 11, both cylinders 214 and 216 have two planar faces 236 and 238 substantially parallel to each other which, when are opposed in the rest position of the apparatus depicted in figure 8, define a passage for the paper sheet, indicated by the numeral 240, advancing according to the direction of the arrow H. The paper sheet 240 has, at a preset and constant distance, of each other transversal prepierced lines permitting the tear along them when one of them comes between the roller pairs 210, 212 and the cylinders 214, 216 are with engaged each other by rotation so that they come in frictional contact with the paper sheet 240. Each of the portions of the cylinders 214, 216 which engage with friction the paper sheet 240 consists of a convex portion 242, 244 comprised between the planar faces 236, 238 of the cylinders 214, 216. As it is particularly seen in the figures 9 to 11, according to a basic feature of the device, the cylinders 216 which are downstream with respect the advancing direction of the paper sheet 240 have cross-section larger than that of the cylinders 214 which are upstream with respect to the same direction. As the rotation speed of the shafts 218, 220 is the same, the periferal speed of the convex portions 244 of the cylinders 216 will be higher than that of the convex portions 242 of the cylinders 214. In such a way, when the drive motor 230 is actuated to drive into rotation the cylinders 214, 216 so as to bring them in the positions of the figures 10 and 11, the paper sheet portion 240 located between the above mentioned cylinders undergoes such a tensioning action to cause the tear of the sheet 240 along its transversal prepierced line 246, as schematically depicted in the figure 11. Once the above mentioned tear is effected, the cylinders 214, 216, by still rotating according to the arrows F and G, will return in the position of figure 9 in order to allow a new advancing of the paper sheet 240 until the subsequent prepierced line 246 will be positioned between the above mentioned cylinders. The latter will be rotated again to cause a further tear of said paper sheet 240. The now described cycle is repeated for every prepierced line 246 of the paper sheet. According to a further embodiment based on the embodiment of the figures 8-11, upstream of the tear separation device, i. e. upstream of the cylinders 214, the friction roller pair indicated by the reference 22 in figure 2 is omitted. At the same time, the shafts 218 are no longer directly kinematically connected to the shafts 220 but continuously rotated by proper motor means, so that the cylinders 214 also fulfill the function of traction of the continuous paper web 240 (i. e. 12 in figure 2). However, the presence of the bevels 236 will cause an intermittent advancing of the continuous paper web to take place, which momentarily stops everytime the bevels 236 face each other. The operation of the apparatus, apart from the operation of the tear separation device according to the invention, is the following one. The web 12 is fed to the apparatus and, after having been diverted downwardly by the section bars 14, 16 is advanced by the rollers 22 to the tear means 24, 26 which can be either actuated or not. Preliminarily, it has been provided to set the posion of the abutment 48 depending on the web 12 width. In this advancing phase the above mentioned web is guided by the rods 18, 20. By supposing that the tear separation device has been activated when the fore edge 12a of the form begins to substantially protrude below the tear separation device the compressed air blows through the nozzles 30 are made operative (of course at the proper side in oreder to have the paper sheet bending towards the desired side). It is sufficient the emission of an istantaneous or very short time blow, as continuing the downwardly advancement of the sheet, the latter takes the desired laying i.e. the edge has taken a loop shape of such a length to allow, owing to the advancing speed of the form, to reach the stopping station 62. At this point, as mentioned, the blow emission is interrupted so that the form can extend by gravity and owing to its own resilience, and take the rest position onto the collecting plane 46. This operation is cyclically repeated for all subsequent forms till the desired number of forms is stacked. The succession of the several operating phases can be controlled and set by proper programming means per se known and thus not depicted. The advantages obtainable by the appartatus of the present invention are apparent from what above written and by the way the main advantages have been already pointed out.

Claims: Apparatus for high speed stacking of paper sheets or forms either by accordeon-like folding of a paper continuous web (12;112;240) or by superimposition of separated sheets which are fed in form of said paper continuous web, comprising web tractor rollers (22) towards diverting means (30) of properly spaced portions, forming said sheets on said web, or of the leading edge of said web to a first or a second stopping and/or folding station (62,64,70) arranged on the two opposed sides of of said web or sheets and on stacking plane (46) of said web or sheets, wherein between the inlet side to the apparatus and said diverting means (30) web guide means are provided essentially consisting of a first and second series of rods (18,20) substantially parallel to each other and extending along the advancing direction of the web, the rods of a series being opposed to those of the other series and passsing through grooved portions of the tractor rollers (22) and of rollers (24,26) of web tear separation means actuatable to effect a tear separation of said web along transversal prepierced lines forming said spaced portions or sheets, and wherein said diverting means comprise nozzle means (30) connected to a pressurized air source, said nozzle means being adapted to emit an air blow directed substantially perpendicularly to the plane of the paper sheets coming out from said guide means and downstream said tear separation means. Apparatus according to claim 1, characterized in that said nozzle means are arranged close and below said tear separation means and at the lower end of said guide means and consist of a plurality of nozzles (30) aligned along a line parallel to the advancing plane of the paper web, each nozzle being connected to a common manifold (34) through a shaped duct (32) and said nozzle means feeding a compressed air blow are operated every time a tear separation is effected and such an operation comprises two subsequent and timed emissions of a compressed air blow. Apparatus according to claim 2, characterized in that each shaped duct (32) is housed in a hollow space between the cylinders (126') forming said rollers of the tear separation means. Apparatus according to claim 1, characterized in that said tear separation means comprise: a first pair of upstream cylindrical rollers (24,117,118) facing each other and constantly or intermittently in frictional contact with said web, each roller possibly having a planar bevel and rotating around its own axis at a constant peripheral speed and in opposed direction for the downward advancement of said continuous paper web along a preset path, a second pair of downstream cylindrical rollers (26,125,126), each of them being provided with a planar bevel (128), said bevels facing each other and being spaced with respect said web and showing a substantially equal extension, said second pair being arranged down stream with respect to said first pair, the rollers of said second pair (26,125,126) being rotatable on command around their own axes and in opposed direction to make at least a complete turn with a peripheral speed higher than that of the rollers (24,117,118) of said first pair, said rollers coming in frictional contact with said web; and wherein at least a roller of said second pair comprises a series of cylinders (126') spaced from each other and aligned along their own axes, said cylinder series comprises at least a central cylinder (145,146) and lateral cylinders (141,142,143,144), so that said central cylinders come in frictional contact with said web in advance with respect to the lateral cylinders. Apparatus according to claim 4, characterized in that the central cylinders are less in number with respect to the lateral cylinders. Apparatus according to claim 4, characterized in that the advanced staggering of the central cylinders is at an angle of not less than 5°. Apparatus according to claim 4, characterized in that the advanced staggering of the central cylinders is comprised in an angle between 5° and 10°. Apparatus according to claim 4, characterized in that the cylinders of the upstream rollers and those of the downstream rollers have at least two planar areas substantially parallel and arranged at 180° to each other and at least two convex areas symmetrical with respect to said planar areas and also arranged at 180° to each other. Apparatus according to claim 4, characterized in that the two rollers pairs are actuated by only one control motor.

Inventors: MESCHI LUCIANO, MESCHI, LUCIANO
Applicants: MESCHI IND GRAFICA, INDUSTRIA GRAFICA MESCHI S.R.L.
Application year: 1991
Main classification: B65H35
IPC codes: B65H29, B65H35