Apparatus for folding and stacking a continuous sheet of paper

Abstract

 Apparatus is disclosed for folding and stacking a continuous sheet (50) of paper which is provided with transverse perforations lines. An air outlet (56) positioned over the stacker is utilized for emitting a starting air stream on a side of the starting portion of the sheet of paper to convey it to a fence (14,16) associated with a guide roller system (30,32,34,36) positioned a the opposite side. Compacting and retaining means (66,86) are lovered as the sheet of paper contact the fence and a support plane (12) receiving the sheet.

Description

[0001] The present invention relates to an apparatus for folding and stacking a continuous sheet of paper which is provided with transverse perforations lines, said apparatus being generally associated with computer printers and more particularly with laser printers operating at high speed.

[0002] The transverse perforations lines have a predeterminde pitch and the folding of the sheet of paper occours in correspondance of said lines.

[0003] A number of apparatus for folding and stacking a continuous sheet of paper are known from the prior art.

[0004] For example the Italian Patent Application No. 22.536 A/88 filed on November 7, 1988 at the name of the same Assegnee of this Patent Application discloses an apparatus having a support plane for receiving the folded and stacked sheet of paper, said plane being provided with a pair of axially speced fences and two rollers rotating in opposite sense at higher speed than that of the sheet feeding to convey the sheet against said fences where the sheet is folded in correspondance of predetermined transverse perforations lines and stacked on the plane; a mechanical device is provided over the plane to guide the sheet of paper towards one of the two rollers.

[0005] This apparatus works well even if said mechanical device is rather complicate and expensive to be properly realized.

[0006] The US Patent No. 4.460.350 discloses an apparatus for folding and stacking a continuous sheet of paper on a receiving plane, the apparatus is provided with air jets located on opposite side of said sheet for emitting alternate directional streams of air thereon. Said air jets are activated by signals detecting the position of the transverse perforations lines whereby synchronization with the passage of said lines opposite said air jets is effected to cause consecutive sheets to fold over one another for forming a stack of paper on the receiving plane.

[0007] It is apparent from the above that the apparatus needs heavy and sophisitcated electrical circuitries in order to obtain the alternance and synchronization of the air jets operations. In the French Patent No. 1.376.538 it is disclosed an other apparatus in which a series of four outlets is provided for emitting air jets, two of them for alternately conveying the continuous sheet of paper to each side of a receiving device, the othr two outlets for pressing the folded sheet of paper on said receiving device.

[0008] The US Patent no. 4.494.948 discloses an apparatus utilizing a pair of curved surfaces over which an air flow is alternately directed to alternately create an air film over each of the curved surfaces. This air film attracts the paper in such a manner that the continuous sheet of paper is folded on a stacker.

[0009] In the European Patent Application No. 0.046.226 it is disclosed an apparatus in which two air jets located on opposite sides of the continuouus sheet of paper for emitting directional streams of air on the line of folding. The direction and/or intensity of said stream are controlled in order to obtain a compact stack of paper on the receiving plane.

[0010] The purpose of this invention is to provide an apparatus for folding and stacking a continuous sheet of paper, the structure of which is simpler and more effective than that of the known apparatuses.

[0011] In one aspect of the invention this is accomplished by an apparatus for folding and stacking a continuous sheet of paper which is provided with transverse perforations lines having a predetermined pitch comprising:
- a support plane for receiving the folded and stacked sheet of paper,
- a pair of axially spaced a part adjustable fences uprightly extending from said plane, the distance between said fences corresponding to the pitch of said transverse perforations lines, characterized in that:
- compacting and retaining means are lying awially inwardly and adjacent to each fence, said means having an upper and lower position, said means at said lower position being in contact with the sheet of paper lying on the support plane and touching one of said fence along one of said transverse perforations lines,
- a system of guide rollers being arranged axially inwardly and in proximity to said compacting and retaining means,
- at least a forced air outlet being positioned over said plane and on a side of said sheet of paper and being oriented in direction of the fence on opposite side, said outlet being open only for emitting a starting air stream on a starting portion of the sheet paper and being finally closed as the compacting and retaining means adjacent to said fence are at said lower position.

[0012] In a preferred embodiment of the invention said system of guide rollers comprises a first pair of rollers axially spaced a part and axially inwardly to said fences, said rollers being ranged on a first and second shaft, a space existing between two adjacent rollers of said first pair, said rollers rotating in a sense to push the sheet of paper again said fences, and a second pair of rollers axially spaced a part and underlying the said first pair of rollers, said rollers of said second pair being ranged on a third and fourth shaft a space existing between two adjacent rollers of said second pair, the rollers of said second pair rotating in a sense to push the sheet of paper against said fences.

[0013] Preferably the rollers of said first pair have a diameter larger than that of the rollers of said second pair.

[0014] Preferably said first and second shaft are fixedly connected to supporting means, said third and fourth shaft being pivotally connected respectively to said first and second shaft.

[0015] Preferably said rollers are tangent to the sheet of paper at surfaces of said rollers axially inwardly to axis of said rollers.

[0016] According to a preferred embodiment of the invention said compacting and retaining means comprise at least an upright plate, parallel to said fences, said plate having a slide running along a vertical guide connected to supporting means, said slide being connected to an actuator for periodically moving said plate from the upper to the lower position and viceversa.

[0017] Preferably said plate has at least an horizontal projection at its lowest edge.

[0018] Preferably said projection is provided with upright fingers passing among shafts of said rollers and through spaces existing between two adjacent rollers ranged on each shaft.

[0019] According to a further preferred embodiment of the invention a further auxiliary system of air outlets is arranged between each fence and a roller axially closest to said fence, said system comprising a main duct connected with an air source and extending horizontally through a length of said fence, a number of pipes departing from said main duct and extending to nearly the sheet of paper on the support plane.

[0020] The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. It is to be expressaly understood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

[0021] In the drawings:

- Fig. 1 is a front elevation view of the apparatus according to the present invention;

- Fig. 2 is a perspective partial view of the rollers system and compacting means of Figure 1.

[0022] Referring to the Figure 1, it can be seen that the folding machine 10 comprises a support plane 12 delimitated at two apposite sides by a pair of axially spaced a part fences 14,16 which determine the format of a paper package to be packed up on the support plane 12.

[0023] The distance between the fences is adjustable according to the arrows 18,20 and said distance corresponds to the pitch length of transverse perforations lines or weakened lines pre-existing on the continuous sheet of paper 50 coming from a high speed printer (not shown) which may be, for example, employed with a computer device.

[0024] The fences 14,16 extend upright from the support plane and below said plane passing through corresponding slots in said plane; the fences are fixed to supporting beams 22,24 which are slidable in the direction of the arrows 18,20.

[0025] The supporting beams have axially inwardly brackets 26,27 (Fig. 2) bearing the shaft 38 on which are mounted a series of rolles 30; the shaft 38 is connected with the underlying shaft 42 by means of pivoting bars 28; on the shaft 42 are mounted a series of rollers 34; the rollers 30 have a diameter larger then that of the rollers 34.

[0026] The same structure is applied to rollers 32,36 respectively mounted on shafts 40,44.

[0027] All the rollers 30,32,34, 36, axially inwardly to said fences, rotate on the respective shafts in the sense indicated by the arrows of Fig. 1, that is towards the inner side of the support plane 12 for conveying the sheet of paper 50 to said fences and said plane.

[0028] As it can be seen from Fig. 2, the series of rollers 30 includes cylindrical elements 30 a-i ranged on the shaft 38, a space existing between two adjacent cylindrical elements; the series of rollers 34 includes cylindrical elements 34 a-i ranged on the shaft 42, a space existing between two adjacent cylindrical elements; both the shaft 38 and 42 are rotary moved by a motor (not shown).

[0029] The cylindrical element 30a is drawn only partially for the purpose to show the compacting and retaining means housed in said spaces between two adjacent cylindrical elements.

[0030] A continuous sheet of paper 50 provided with transverse perforations lines having a predeterminated pitch length, which is to be folded to form a package on the support plane 12, is passing through the guide members 51a, 51b substantially positioned on the vertical axis of the support plane 12 and over said plane; the head or starting portion of said sheet of paper is oriented towards the rollers 32,36 and therefore to the fence 16 by air streams emitted by a series of outlets 56 connected with the duct 52.

[0031] In respect of the vertical axis of the plane 12, the outlets 56 and the fence 16 are positioned at opposite sides and the outlets 56 are substantially oriented in direction of the fence 16 and/or the corresponding lateral portion of the plane 12.

[0032] As shown in Fig. 1, the starting portion of the sheet of paper 50, indicated by dashed line, reaches the axially inwardly surfaces of the rollers 32,36 and is substantially tangent to said surfaces, the rollers surfaces guide said starting portion of the sheet against the fence 16 and on the plane 12.

[0033] The surfaces of the rollers 32,36 are made of material having a high friction coefficient (i.e. rubber compound) and the rotating speed of the rollers is higher than the linear speed of the advancing sheet of paper, so that said sheet is dragged down by said rollers.

[0034] As the head of the sheet of paper contacts the fence 16 and the corresponding edge of the plane 12, the compacting and retaing means 26 is lowered (as indicated by dots and dashes lines in Fig. 1) to fix said sheet head against the support plane 12, the outlets 56 are finally closed so that the air streams cease to be emitted and the sheet of paper continuing to be feeded to the folding apparatus lies down the plane 12 and moves towards the opposite fence 14.

[0035] It will be noted that the air streams emitted by the outlets 56 are working only to convey the sheet head (or starting portion of the sheet of paper) to the fence 16 and cease to operate thereafter, for this reason they are defined as "starting air streams".

[0036] The compacting and retaining means includes an upright plate 66, 86 positioned axially inwardly and parallel to said fences.

[0037] The plate 66 has a slide 70 running along a vertical slot 72 of a guide 76 which is fastened to the beam 22; the slide 70 is periodically moved from an upper to a lower position and viceversa by a piston-cylinder 80 activated by a known timing device.

[0038] At the lower position the plate 66 is in contact with the sheet of paper lying on the support plane 12; at the upper position the plate 66 allows the sheet of paper to go against the fence.

[0039] The plate 66 has at least an horizontal projection extending axially inwardly at its lowest edge and said projection is provided with upright fingers 68 passing between the shafts 38 and 42, and through the spaces existing between two adjacent cylindrical elements ranged on each shaft.

[0040] The fingers 68 restrict the movement of the privoting shaft 42 in respect of the fastened shaft 38 and prevent the sheet of paper to enter between the rollers 30 and 34.

[0041] The same structure is applied to the compacting and retaining means 86 positioned on the opposite side.

[0042] The folding apparatus 10 is further provided with an auxiliary system of air outlets 110,112 arranged between each fence 14,16 and a roller 34,36 axially closest to said fences.

[0043] Referring to the outlets 110, said system includes a main duct 114 connected with an air source 122 and extending horizontally through a length of the fence, a number of piper 118 a-b departing from said main duct and extending vertically to nearly the sheet of paper on the support plane 12.

[0044] The air streams emitted from the outlets 118 a-h are directed towards the sheet of paper in proximity of its folding line to flatten the same against the underlying support.

[0045] The air streams can be timed by usual means to act, for example, when the sheet of paper contacts the respective fence.

[0046] In order to store up a packaging of a desired thickness on the support plane 12, said plane can be lowered according to the arrow 130.

[0047] For this purpose a light emitting device and a light receiver 134 are positioned on opposite sides of the plane 12 and at a certain height from said plane, when the thickness of the packaging shuts the light out, the detector 132 sends a signal to activate a motor (not shown) which provides to lower the plane 12.

[0048] Continuing the description of the further operations of the folding apparatus after the sheet head has been retained against the support plane 12 and the outlets 56 definitively closed, the sheet of paper coming down from the guide members 51a, 51b moves towards the fence 14.

[0049] The sheet by contacting the rotating rollers 30,34 forms a bend 64 touching said fence 14 near the plane 12.

[0050] It will be noted that the sheet 50 is able to push the rotating privoting roller 34 and shift it axially outwardly, so that said sheet will touch firstly the fence 14 and then the plane 12.

[0051] The plate 66 is then lowered to press the bend against the plane and to define a folding on the sheet of paper coinciding with a transverse perforations line and retaining there the paper.

[0052] The folding in correspondence of the fence 14 deviates the sheet of paper coming down from the guide members 51a,51b towards the axis of the plane 12 and then to the opposite fence 16.

[0053] In the meanwhile the plate 86 has been lifted to leave a free space allowing the sheet of paper to reach again the fence 16.

[0054] By repeating the above operations a packaging of paper sheets is stored up the plane 12 and when the thickness of said packaging is hight enough as to shut out the light of an emitting device, the plane 12 is lowered, as mentioned above, until the final package is made; then the sheet of paper is cut along a transverse perforations line and the package removed from the apparatus.

[0055] The apparatus of this invention is disclosed by referring to a preferred embodiment, it will be understood that light modification departing from the above description will be regarded as pertaining to this invention.

Claims

1) An apparatus for folding and stacking a continuous sheet of paper which is provided with transverse perforations lines having a predetermined pitch comprising:
- a support plane (12) for receiving the folded and stacked sheet of paper,
- a pair of axially spaced a part adjustable fences (14,16) uprightly extending from said plane, the distance between said fences corresponding to the pitch of said transverse perforations lines, characterized in that:
- compacting and retaining means (66,86) are lying axially inwardly and adjacent to each fence, said means having an upper and lower position, said means at said lower position being in contact with the sheet of paper (50) lying on the support plane and touching one of said fence along one of said transverse perforations lines,
- a system of guide rollers (30,32,34,36) being arranged axially inwardly and in proximity to said compacting and retaining means,
- at least a forced air outlet (56) being positioned over said plane and on a side of said sheet of paper and being oriented in direction of the fence on opposite side, said outlet being open only for emitting a stacking air stream on a starting portion of the sheet paper and being finally closed as the compacting and retaining means adjacent to said fence are at said lower position.

2) Apparatus according to claim 1 characterized in that said system of guide rollers comprises:
- a first pair of rollers (30,32) axially spaced a part and axially inwardly to said fences, said rollers being ranged on a first and second shaft (38,40), a space existing between two adjacent rollers of said first pair, said rollers rotating in a sense to push the sheet of paper again said fences,
- a second pair of rollers (34,36) axially spaced a part and underlying the said first pair of rollers, said rollers of said second pair being ranged on a third and fourth shaft (42,44) a space existing between two adjacent rollers of said second pair, the rollers of said second pair rotating in a sense to push the sheet of paper against fences.

3) Apparatus according to claim 2 characterized in that the rollers of said first pair have a diameter larger than that of the rollers of said second pair.

4) Apparatus according to claim 2 characterized in that said first and second shaft are fixedly connected to supporting means (22,24) said third and fourth shaft being pivotally connected respectively to said first and second shaft.

5) Apparatus according to claim 2 characterized in that said rollers are tangent to the sheet of paper at surfaces of said rollers axially inwardly to axis of said rollers.

6) Apparatus according to claim 1 characterized in that said compacting and retaining means comprise at least an upright plate (66), parallel to said fences, said plate having a slide 70 running along a vertical guide connected to supporting means, said slide being connected to an actuator for periodically moving said plate from the upper to the lower position and viceversa.

7) Apparatus according to claim 6 characterized in that said plate has at least an horizontal projection at its lowest edge.

8) Apparatus according to claim 7 characterized in that said projection is provided with upright fingers (68,88) passing among shafts of said rollers and through spaces existing between two adjacent rollers ranged on each shaft.

9) Apparatus according to claim 1 characterized in that a further auxiliary system of air outlets (110,112) is arranged between each fence and a roller axially closest to said fence, said system comprising a main duct (114) connected with an air source (122) and extending horizontally through a length of said fence, a number of pipes (118) departing from said main duct and extending to nearly the sheet of paper on the support plane.

Drawing