A MACHINE FOR CUTTING A PAPER WEB INTO SHEETS WITH SIMULTANEOUS CUTTING OF A TRANSVERSE STRIP

Abstract: A machine (1) serves to cut a paper web or a similar material (2) into sheets (34) with simultaneous cutting of a transverse strip (35). The machine comprises a stationary bottom knife (9) and an overlying, rotatable, solid knife cylinder (15) having a chord face (20) on which an inner knife (16) and an outer knife (17) are fixed for cutting a sheet (34) and a strip (35), respectively, from the paper web (2) when the knives (16, 17) pass close above the bottom knife (9) during rotation, while the paper web is advanced at a suitable rate between the knives by two vacuum rollers (3, 4). The knife cylinder (15) and the knife setup (16, 17) offer great resistance to bending. The machine lends itself for cutting paper webs in inch modules into e.g. A4 sheets which can be used in modern laser printers which are designed for the millimeter system.

Description: A machine for cutting a paper web into sheets with simul¬ taneous cutting of a transverse strip The invention concerns a machine for cutting a paper web or a similar material into sheets with simultaneous cut¬ ting of a transverse strip for each sheet, comprising a stationary bottom knife arranged transversely to the paper web and a rotatable knife cylinder arranged over said bottom knife and likewise transversely to the paper web and having at least one set of mutually associated knife cutting edges which, by close passage of the bottom knife during the rotation of the knife cylinder, successively cut a sheet and a strip, respectively, from the paper web while said paper web is advanced continuously between the bottom knife and the knife cylinder. The electronic data processing technology has its origin in the USA where the inch system is used for measuring lengths. From the outset electronic data processing ma- chinery as well as EDP related external printing machines have therefore been designed for advancing and printing endless lists with modules in inches. In countries using the metric system this has caused problems of e.g. filing, and the inch modules do not fit the new generations of modern laser printers which can only work with formats based on the metric system. In countries using the metric system paper webs divided into inch modules must therefore be cut into sheets to a great extent, which are standard¬ ized within the metric system, a narrow strip being cut for each sheet. Paper webs which e.g. have a module of 12 inches are thus cut down to 297 mm, i.e. A4 format, with simultaneous cutting of a strip of about 7.8 mm from each sheet. The patent publication WO 82/00970 describes an apparatus capable of performing such an operation. This construction has a stationary bottom knife and an overlying knife cy¬ linder having two knives arranged on their respective sides of a relatively wide slot, which is cut along the knife cylinder and extends into a bore which is provided centrally in the cylinder and extends out to one of the ends of the cylinder where it communicates with a source of vacuum. This arrangement serves to remove the strips as soon as they have been cut from the paper web, the strips being immediately sucked up into the central bore of the knife cylinder via the space between the knives and the longitudinal slot, following which the strips continue axially out through the bore to a collection point. Cut- ting does not take place as a cutting operation proper, but is more in the nature of a linear compression of the paper of a magnitude such that the fibres of the paper are crushed and torn across. This process requires very big forces which the knife cylinder must be capable of absorb- ing. However, the knife cylinder is greatly weakened by the longitudinal slot and the central bore and therefore tends to bend at the center during cutting, which will thus tend to be deficient so that some of the strips are not cut cleanly, but are still partly connected to the sheets to the detriment of the following operations. The weak and unstable construction moreover entails that the knives are worn relatively quickly, and that their cutting edges are liable to be crushed, because it is difficult to adjust the knife distance with the necessary accuracy. With a view to overcoming the above-mentioned drawbacks, the object of the invention is to provide a machine of the type mentioned in the opening paragraph, which has a knife cylinder offering greater resistance to bending than known before, and a knife arrangement permitting quick and ex¬ tremely accurate adjustment of the knife distance so that the machine is capable of cutting strips and sheets from a continuous paper web with clean and perfect cuts, contin¬ uously and without heavy wear of the knives. This is achieved by means of the novel and unique features of the invention, wherein the knife cylinder is substan¬ tially solid, and the knife cutting edges of a mutually associated set are present on a cross-sectionally substan¬ tially rectangular knife device which, with one of its faces, is fixed against a chord face provided on the knife cylinder. To be able to cut the relatively thin paper by crushing the fibres in it the cutting edge of the knife cylinder and the cutting edge of the bottom knife must pass each other at such a small distance that they almost meet each other. Even small variations in this extremely small dis¬ tance can lead to serious operational stoppages. If the distance is reduced, the cutting edges will tend to crush each other, and if the distance is increased, this can entail that the paper web is not cut cleanly. The latter case may involve costly loss of paper, which is destroyed before the error is observed and corrective measures are taken manually, because machinery of this type has a very great production rate. By means of the above-mentioned construction of the invention both the knife cylinder and the knife setup can be made so stiff that practically no bending takes place because of the hugh load which occurs during cutting. Thus, a constant and uniform cutting edge distance in the overall longitudinal extent of the knives can be maintained continuously in operation. This entails that the machine is capable of working with extremely great liability and of making a product of superior qual¬ ity. Another advantage obtained is that the cutting edge distance can be adjusted easily and rapidly, because there is now no longer any uncertainty with respect to the se- lection of the correct cutting edge distance, as is the case when using the art known from the above-mentioned patent publication WO 82/00970, in which the selection must necessarily always be based on a compromise between extreme positions unacceptable per se. The ability of the present construction to maintain a constant and uniform cutting edge distance moreover imparts a long life to the tools. The cut strips are normally to be removed before they, and the cut sheets, arrive at the subsequent production sta¬ tions where their presence might cause considerable da¬ mage. For the cut strips to be removed effectively and safely immediately, a longitudinal groove may be cut be- tween the cutting edges of the knife device in an advan¬ tageous embodiment, said groove communicating via a channel system in both the knife device and the knife cylinder with a valve arrangement to connect the groove, during the cutting process, with a source of vacuum during cutting and then with a source of compressed air or the atmosphere. Each of the cut strips will hereby be sucked up into the longitudinal groove between the cutting edges as soon as it has been cut from the paper web. Because of the vacuum the strip remains in the groove until the knife cylinder has rotated through a suitable angular distance from the bottom knife, and then the strip is blown away from the knife cylinder by means of compressed air. A suc¬ tion funnel may optionally be arranged at the location where the stip is blown off, said funnel communicating via a channel with a source of vacuum and serving to remove the strips completely from the work place. In the latter case, it will usually be sufficient to have the valve arrangement close the vacuum and connect the longitudinal groove between the cutting edges with.the atmosphere. In a particularly advantageous embodiment the knife device may be composed of an inner knife fixed against the chord face of a knife cylinder and an outer knife fixed against the outer side of the inner knife, said outer knife carry- ing the cutting edge for cutting the sheet, and said inner knife carrying the cutting edge for cutting the strip. It will hereby be easier to sharpen the cutting edges which are now located on their respective knives. The machine can moreover be switched over to cutting the paper strip from one or the other of the two modules rapidly and in a simple manner. When just the inner knife is mounted, the machine will thus cut the paper web into inch formats, and when also the outer knife is mounted, the paper strip will be cut into millimeter formats. To facilitate the manufacture and sharpening of the inner knife additionally, its cutting edge can advantageously be in the same plane as its outer side. In a particularly simple embodiment the cutting edge of the outer knife may be formed by the outer side of the knives and the bottom face of the groove. This cutting edge is easy to sharpen, but since the angle is obtuse, a relatively great force is required to cut the paper web. This force is reduced when the cutting edge of the outer knife is formed by the outer side of the knife and a face extending obliquely downwards toward the edge member of the cutting edge from the bottom face of the groove. The invention will be explained more fully by the follow¬ ing description of embodiments, which just serve as ex¬ amples, and further advantageous properties and technical effects will be disclosed, with reference to the drawing, in which fig. 1 is a schematic top view of a machine according to the invention, fig. 2 is a partially sectional, lateral view of the same, fig. 3 is a lateral view of a valve disc for the machine shown in figs. 1 and 2, fig. 4 shows the machine of figs. 1 and 2 along the line IV-IV in fig. 2, and illustrates an inner knife and an outer knife, a portion of one end of each of the knives being removed to show the arrangement of the underlying parts, fig. 5 is an enlarged, partially sectional, lateral view of a fragment of a knife device associated with the ma¬ chine of figs. 1-4 with the inner knife and the outer knife in a position where the outer knife is cutting a sheet, fig. 6 shows the same, but in a position where the inner knife is cutting a strip, and fig. 7 shows a fraction of a second embodiment of an outer knife. Figs. 1 and 2 show a machine which is generally designated 1 and which serves to successively cut a continuous paper web into sheets and strips, respectively. When the mutual position of the various components of the machine is men¬ tioned below with respect to a vertical plane and a hori¬ zontal plane, this refers to the position which the ma¬ chine assumes in figs. 1 and 2. This, however, just serves as an example, and the machine may have any other spacial orientation within the scope of the invention. The paper web to be cut is designated 2. The paper web, which is wound off a supply roll (not shown), runs over two vacuum rollers 3, 4 in the direction of the arrow. The vacuum rollers, which are connected with a source of vacuum (not shown) in a known manner via a conduit 5, serve to advance the paper web 2 over a table 6. Usually, the right vacuum roller 4 rotates faster than the left vacuum roller 3 to keep the paper web smoothly stretched during cutting and then to remove the cut sheet quickly. The figures show the simple case where the width of the paper web corresponds to the width of the resulting sheet. However, in practice the paper web is frequently so wide as to accommodate several sheets juxtaposed. The paper web is then first cut longitudinally to the desired format width before arriving at the machine for cutting the web transversely. Since the knife cylinder is now to cut seve¬ ral sheets at once, it must necessarily have a correspond¬ ingly great distance between the supports in the bearings, and since bending increases to the fourth power with this distance, the demands on the stiffness of the knife cylin¬ der are intensified to an extremely great degree. An inclined, stationary bottom knife 9 is fixed to an up¬ standing knife holder 7, which is mounted on a frame 8 associated with the machine, by means of a plurality of screws 10 which extend through elongate openings 11 per¬ mitting the knife to be displaced transversely when it is to be adjusted. This adjustment takes place by means of set screws 12, which also serve to absorb the power compo- nent acting in the plane of the bottom knife during cut¬ ting. The bottom knife 9 extends via a slot 14 in the table up through said table at a height where the edge 13 of the knife is flush with the to side of the table and thus the underside of the paper web 2. A solid knife cylinder 15 carrying an inner knife 16 and an outer knife 17 is mounted at a distance above the table 6 and the bottom knife 9. As shown in fig. 1, the knife cylinder is rotatably mounted in bearings 19 provided on side members 18 associated with the frame 8 of the ma¬ chine» Also the vacuum rollers 3, 4 are rotatably mounted in bearings (not shown) in these side members 18. The knife cylinder 15 and the side members 3, 4 are all caused to rotate by means of a drive arrangement (not shown) known per se. A portion of the knife cylinder 15 has been cut away to form a chord face 20. As shown in figs. 2 and 4, the inner knife 16 is fixed to this chord face 20 by means of screws 21, which extend through elongate openings 22 permitting the knife to be set and adjusted transversely. The inner knife 16 is provided with threaded holes 23 serving to fix the outer knife 17 on the exterior of the inner knife 16 by means of screws 24 which extend through elongate open- ings 25 permitting the outer knife to be displaced trans¬ versely. A fillet 27 is fixed to the rear edge of the inner knife 16 by means of screws 26. Setting and adjust¬ ment of the outer knife 17 takes place by means of set screws 28 in this fillet 27. These set screws 28 moreover serve to absorb the component of the forces acting in the plane of the knife during cutting. The knife cylinder 15 is moreover provided with a projection 29 having set screws 30 for setting and adjusting the inner knife 16. These set screws 30 likewise serve to absorb a component acting in the plane of the knife during cutting. As shown best in figs. 5 and 6, the inner knife 16 has an edge 31 and the outer knife 17 an edge 32. The two edges 31, 32 define a longitudinal groove 33. When the knife cylinder 15 rotates, the two edges 31, 32 one by one pass the edge 13 of the bottom knife 9 at such a small distance that it cannot be indicated in the drawing. In fig. 5 the edge 32 of the outer knife 17 just meets the edge 13 of the bottom knife 9, thereby crushing the fibres of the paper along a line, and the sheet 34 disposed to the right is torn off the paper web 2. Since the right vacuum roller 4 rotates faster than the left vacuum roller 3, the sheet 34 is then rapidly moved further on to e.g. a stacker. In fig. 6 the edge 31 of the inner knife 16 meets the edge 13 of the bottom knive 9, thereby cutting a transverse strip 35 from the paper web 2. If the paper web is divided into inch measures with a module of e.g. 12 inches, and the finished sheets are to be in A4 format with a length of 297 mm, it is necessary for each sheet to cut a strip of about 7.8 mm. When both knives 16, 17 are mounted as shown in figs. 5 and 6, the paper web is thus cut into millimeter formats. The machine can directly be switched over to cutting the paper web into inch formats instead merely by dismounting the outer knife 17. This involves the considerable advantage that one and the same machine can be used equally well within both systems of measure¬ ment. As shown, one side of the cutting edge of the inner knife 16 is disposed in the same plane as the outer side of the knife. This imparts a simple structure to the knive, which is easy to sharpen and keep in good order. The outer knife 17 shown in figs. 5 and 6 has a cutting edge with an ob¬ tuse angle, which is likewise easy to sharpen and keep in good order. On the other hand, greater forces are required to crush the fibres of the paper. These forces are smaller than in the embodiment shown in fig. 7, in which the outer knife 17 has a cutting edge with an acute angle. As mentioned before, it is necessary to remove the strips 35 before they arrive at the subsequent production steps and cause damage here. This problem is solved by sucking the cut strips 35 up into the groove 33, which communi¬ cates via a channel system with a valve arrangement, which is connected with a vacuum source (not shown) and a com- pressed air source (not shown) or the atmosphere. In the situation shown in fig. 6 the groove 33 is connected with the vacuum source, and the strip 35 is held in the groove 33 by suction. In fig. 2 the knife cylinder 15 is shown in dotted line in a position in which it has now been rotated through an angle of about 180°. A suction funnel 38 is ar¬ ranged at this location in the vicinity of the knife cy¬ linder, said suction funnel being connected with a vacuum source (not shown) via a channel 39. The valve arrangement 37 now applies a positive pressure to the groove 33 in- stead of a negative pressure, whereby the strip 35 is blown up into the funnel 38 and is removed from the work place via the channel 39. If the suction above the funnel 38 is sufficiently strong, it will in most cases merely be necessary to connect the groove 35 with the atmosphere when the strip is to be removed from the knife cylinder. The valve arrangement 37 is shown more fully in figs. 3 and 4. The valve arrangement substantially consists of a metal or plastic ring 40 which carries a valve ring 41, which may expediently be of plastics. The valve ring 41 rests slidingly rotatably on a ground steel ring 42 which with a spline 43 is splined to the knife cylinder 15, such that it follows the rotation of the knife cylinder. The valve arrangement 37, on the other hand, is stationary. As shown, a valve arrangement 37 is provided at each end of the knife cylinder 15. However, in other cases it will be sufficient merely to have a valve arrangement at one end of the knife cylinder. As shown best in figs. 4, 5 and 6, a channel system con¬ necting the groove 33 with the valve arrangement 37 is provided in the knife cylinder and the knives. This system comprises a longitudinal groove 44 which is cut in the knife cylinder 15 and opens toward the chord face 20. Holes 45, extending from the end faces of the knife cylin¬ der into the groove 44, communicate with the valve ar¬ rangement 37 via corresponding holes 46 in the steel rings 42. Similarly, a longitudinal groove 47, 48 is provided in the inner knife 16 in alignment with the groove 44 of the knife cylinder on each side of the inner knife 16. These grooves are in turn interconnected by means of a plurality of transverse holes 49. Further, the inner side of the outer knife 17 is formed with a longitudinal groove 50 aligned with the groove 48 on the outer side of the inner knife 16. This groove 50 is in turn connected with the longitudinal groove 33 between the cutting edges of the knife cylinder by means of a plurality of suction holes 51. As shown in figs. 3 and 4, the valve ring side facing the steel ring 42 is provided with a curved slot 54 connected with the vacuum source (not shown) via a conduit 52. Simi¬ larly, another slot 55 is provided, which is merely in the form of a hole in the shown case, and which is connected with the compressed air source (not shown) or the atmos¬ phere via a conduit 53. In the situation shown in fig. 2, the hole 45 in the end face of the knife cylinder is aligned with the vacuum slot 54. Vacuum then prevails in the longitudinal groove 33 between the cutting edges of the knife cylinder, so that the cut strip is held in the groove by suction, and this continues until the knife cylinder has rotated so much that the hole 45 has passed the slot 54. This inter¬ rupts the vacuum, which is immediately replaced by a posi- tive pressure or the pressure of the atmosphere when the hole 35 rotates into the position in front of the com¬ pressed air slot 55. The held strip 35 is now sucked up into the suction funnel 38, as described previously. The invention is described above and shown on the drawing on the basis of the exemplary assumption that it was paper webs that were to be cut into either inch or millimeter measures. It goes without saying that the machine of the invention can equally well be used for cutting endless webs of another thin material than paper and into sheets and strips of any size, which merely depends upon the di¬ mensions of the knife cylinder and the knives. Further¬ more, more than one set of knives may be provided on the knife cylinder.

Claims: P a t e n t C l a i m s : 1. A machine for cutting a paper web or a similar mate- rial into sheets with simultaneous cutting of a transverse strip for each sheet, comprising a stationary bottom knife arranged transversely to the paper web and a rotatable knife cylinder arranged over said bottom knife and like¬ wise transversely to the paper web and having at least one set of mutually associated knife cutting edges which, by close passage of the bottom knife during the rotation of the knife cylinder, successively cut a sheet and a strip, respectively, from the paper web, while said paper web is advanced continuously between the bottom knife and the knife cylinder, c h a r a c t e r i z e d in that the knife cylinder is substantially solid, and that the knife cutting edges of an associated set are provided on a cross-sectionally substantially rectangular knife device which, with one of its faces, is fixed against a chord face provided on the knife cylinder. 2. A machine according to claim 1, c h a r a c t e r ¬ i z e d in that a longitudinal groove is cut in the knife device, said groove being defined along the sides by the knife cutting edges. 3. A machine according to claim 1 or 2, c h a r a c ¬ t e r i z e d in that the knife device is composed of an inner knife fixed against the chord face of the knife cy- under and an outer knife fixed against the outer side of the inner knife, said outer knife carrying the cutting edge for cutting the sheet, said inner knife carrying the cutting edge for cutting the strip. 4. A machine according to claim 1, 2 or 3, c h a r a c ¬ t e r i z e d in that one of the sides forming the cut- ting edge of the inner knife is positioned in the same plane as its outer side. 5. A machine according to one or more of claims 1-4, c h a r a c t e r i z e d in that the cutting edge of the outer knife is formed by the outer side of the knife and the bottom face of the groove. 6. A machine according to one or more of claims 1-5, c h a r a c t e r i z e d in that the cutting edge of the outer knife is formed by the outer side of the knife and a face extending obliquely downwards toward the edge member of the cutting edge from the bottom face of the groove. 7. A machine according to one or more of claims 1-6, c h a r a c t e r i z e d in that the groove communicates via channels in the knife device and the knife cylinder with a valve arrangement for connecting the groove with a source of vacuum during the cutting process and subse- quently with a source of compressed air or the atmosphere. 8. A machine according to one or more of claims 1-7, wherein the knife device is composed of an inner knife and an outer knive, c h a r a c t e r i z e d in that the channels in the inner knive consist of a longitudinal, open groove provided on each side of the inner knife and a plurality of transverse holes connecting the two grooves, and that the channels in the outer knife consist of a longitudinal, open groove which, in assembled state, is positioned in alignment with the outermost groove of the inner knife, and which is provided on the inner side of the outer knife, and a plurality of holes connecting said groove with the groove between the two cutting edges. 9. A machine according to one or more of claims 1-8, c h a r a c t e r i z e d in that the channels in the knife cylinder consist of a longitudinal, open groove which, in assembled state, is positioned in alignment with the innermost groove of the inner knife, and a hole ex¬ tending from at least one end of said open groove, and which terminates in the respective end face of the knife cylinder and connects the channel system with the valve device. 10. A machine according to one or more of claims 1-9, c h a r a c t e r i z e d in that it comprises a suction funnel which is connected with a source of vacuum via a channel, and which is located at an angular distance from the cutting position in the vicinity of the surface of the knife cylinder, said valve arrangement being adapted to switch the pressure in the channel system from vacuum to atmospheric or positive pressure when the groove between the cutting edges of the knife device is aligned with the funnel.

Inventors: GRONBJERG IB, GROENBJERG, IB
Applicants: GRONBJERG IB, GROENBJERG, IB
Application year: 1993
Main classification: B26D1
IPC codes: B26D1, B26D7