A method for the manufacture of a paper web with decorative edge cutting

Abstract

 The invention relates to a method for the manufacture of letter paper with decorative edge cutting by tearing the edge portion of the letter paper along a previously prepared zone along which the letter paper is compressed or provided with a string shaped water mark.

Description

[0001] The present invention relates to a method for the manufacture of a paper web with decorative edge cutting comprising the separation of at least one edge portion of a paper web whilst at the same time a decorative, irregular edge structure is imparted to the outer lateral edge of the web formed by the separation. The invention relates further to a method for dividing such a web cut along the edge into sheets by severing pieces of sheet from the web whilst forming a decorative irregular edge cutting transversely to the web.

[0002] In the manufacture of hand-made paper in the form of sheets a decorative, irregular, outer edge is obtained. However, the manufacture of such paper is very expensive and such hand-made paper occurs, therefore, only to a very limited extent.

[0003] It has been found that paper of the same high, and an even more uniform quality than the existing hand-made paper can be produced by mechanical means, but that the same decorative edge structure is not obtained by this method owing to the mechanical paper being produced in an endless web and not in single sheets.

[0004] However, mechanically made paper of high quality with decorative edge cutting can be produced if the cutting is carried out in a special manner and after special premachining of the paper material. A direction concerning such a method is given in the present patent application, which is characterized in that the paper web is compressed in the separating zone by means of co-operating rollers, whereupon the web is conducted over a roller comprising a cutting or tearing device, e.g. a tear wire, knife or cutting wheel, which is located so that it is made to engage with the said compressed region of the web when the same is led over the roller and that the webwhen it is led past the cutting or tearing deviceis broken up in its longitudinal direction.

[0005] An embodiment of the method in accordance with the invention will be described in the following with reference to the enclosed schematic drawing, wherein

Fig 1. shows an arrangement for the edge and sheet cutting of a paper web,

Fig 2. shows a cross-section of the arrangement for compression of the paper web,

Fig 3. shows an arrangement for the cutting of the longitudinal edges, and

Fig 4. shows the web schematically in its different phases during the cutting into sheets.

[0006] The manufacture of the web or sheet in accordance with the invention is started already during the paper making, where the paper stock in the normal manner is poured onto an endless wire screen. In a known manner so-called watermarks can be obtained in a paper by treating the paper pulp on the screen with a so-called dandy roller. This dandy roller consists of a cylinder clad with a screenlike wire netting. In this wire netting is inlaid a pattern of other wires which on the one hand project a little outside the surface of the wire cylinder and on the other hand reduce the mesh width on the net-clad cylinder. Along the region where additional wires have been inserted so-called watermarks are formed if the dandy roller is made to rotate with the screen and in so doing has its surface in the paper pulp. It is possible in this manner to form longitudinal and transverse zones or edges which form watermarks in the finished paper. It is ensured of course that the width between the "watermark edges" of the dandy roller becomes the desired width of the final web or sheet, and that the distance between the transverse watermark edges will correspond to the desired length of the sheets in the case where the web is intended to be divided up into individual sheets.

[0007] After drying of the paper web holes 42 may be made in the edge portions 41 of the web 2 for the guiding and feeding of the paper web e.g. into a data printer. As is evident from fig.4, the web 2 is provided with longitudinal watermark lines 43 and transverse watermark lines 44 which jointly delimit the sheet 45 which is to be produced, this sheet having a decorative, irregular edge zone 46 in the said watermark zones 44 and 43. This combination of a watermark zone around the edge of the sheet 45 in conjunction with the irregular edge cutting and the otherwise high quality of the paper give the impression of the paper having been hand-made.

[0008] Thus the paper web?is made in the normal manner but is provided with at least longitudinal watermark lines 43 and, if the web is to be converted to sheets, also with transverse watermark lines 44. The said paper web produced is rolled onto a magazine roll 1 which is shown in fig. 1, and the web 2 is led over the deflection rollers 3 to be conducted subsequently to the treatment station I where the web in the longitudinal watermark zones 43 is subjected to a compression with the help of a tool which is arranged on a roller 4 and which operates against a plain hold-on roller 5. On the tool roller 4, which can be pressed against the hold-on roller 5 with the help of a spring or an air cylinder 8, a tool is arranged, the working surface of which has a profile 9 as shown in fig. 2. The compression tool 9 is thus of a convex shape and preferably a V-shape with rounded front surface and when the web 2 is conducted between the rollers 5 and 4 the tool 9 will be pressed into the web 2, and since the tool 9 is arranged around the periphery of the web 4 the tool 9 will during the rolling movement continuously compress a zone A of the web 2 whilst the web is conducted past the roller pair 4 and 5. Owing to the particular shape of the tool 9 the compression will be greatest at the front part of the tool 9 and diminish then towards the edges of the compression zone A. The compressed zone can be made of any width, but in the present case the width of the compressed zone is 1 - 5mm. As is evident from fig. 2, the compressed zone A is located within the zone B which represents the zones 43 with the longitudinal watermark edges. The tool 9 is thus brought into engagement with the web 2 along the longitudinal watermark zones 43 and is guided so that during the whole time the compression zone is inside the watermark zone 43. Since the web 2 has two watermark zones 43, the roller 4 is provided with two annular tools arranged around the periphery of the roller which are adapted so that they both operate within the watermark edge zones 43, and the pressure with which the tool 9 is pressed against the web 2 can be regulated with the help of springs or air cylinders; 8. The tool 9 is preferably made of steel and the plain hold-on roller 5 too is preferably made of steel. The web treated in this manner in station I is conducted to station II which comprises a rotating roller 6, this roller being provided with grooves 20 which are arranged at such a distance from each other that their mutual position corresponds to the compressed watermark zones 43. The station II, moreover, comprises a cutting arrangement 7 which consists of a stationary wire 21, preferably of metal, which is clamped between clamping points 22 fixed to the frame of machine.

[0009] As is evident from fig.3, the wire 21 is clamped in such a manner that it is inclined in respect of the web and forms an acute angle alpha with the web. The wire 21 is located so that it lies in the groove 20 preferably without resting against the roller 6. The wires 21 are preferably adjusted so in their position that they correspond to the position of the compressed zone A on the watermark edges 43.

[0010] When the web 2 is led over the roller 6 the tearing wires 21 will tear up the material web 2 along the compressed parts of the watermark edge zones 43, the outer edges being separated whilst the tearing edge obtains a somewhat irregular edge structure.

[0011] In the station III the separated edge zone 46 is machined again by two co-operating clamp rollers which are pressed against each other in the edge zone, any portions of the edge zone which may have "napped up" being pressed together. The web 2 is led over the deflection roller 10 up to the station IV where two co-operating and controlled clamp rollers compress the transverse watermark zones 44. This compression is carried out with linear pressing tools which are arranged axially to the surface of the clamp rollers 12, and the compression of the transverse watermark zones 44 is carried out in such a manner that the paper web is not completely severed but is substantially weakened in as much as the paper fibres are crushed. It is also possible to arrange on the rollers 12 hinged clippers for the severing of the paper sheets, but in this case it is not possible to achieve the same attractive edge structure as when the paper fibres are crushed and the sheets 45 are subsequently separated from the web 2 by pulling until the weakened watermark zone is caused to break. The cylinders 11 in the station IV have to be controlled so that the tools will engage at the right place, that is to say within the watermark edge 44 and this can be done e.g. by means of a photocell control. This control functions so that a photocell indicates the position of the watermark zone 44 which is more transparent than the surrounding portions, whereupon a signal is transmitted to the driving unit for the pair of rollers so that the tools 12, 13 will engage with the paper web 2 precisely in the transverse watermark zones 44. In case the web 2 is not completely severed but only weakened through compression of the watermark zone 44 the web is introduced between two driven rollers 14 which are driven by a motor 15 by means of a belt 16. In the tear-off station IV the web 2, after it has left the rollers 14, is-led further to the rollers 19 which with the help of a transmission 17 are driven by a gear which imparts an intermittent speed to the rollers.

[0012] In the station IV the individual sheets 45 are severed from the web 2 in that the front part of the web is torn or pulled loose from the rest of the web, the severing taking place along the weakened watermark zone 44. The tearing off takes place so that the web is advanced by and is held tight between the rollers 14 and that the front end of the web 2 is similarly advanced and held tight between the rollers 19. To the pair of rollers 19 a rate of feed is imparted in a first phase which is less than the rate of feed of the pair of rollers 14. This means that the part of the web 2 which is between the pairs of rollers 14 and 19 is slightly slackened. In a second phase, though the rate of feed of the pair of rollers 19 is increased so that it becomes higher than the rate of feed of the pairof rollers 14 and when this happens the web is suddenly stretched, the tensile stresses in the web becoming so great that it breaks along the compressed and weakened portion which is located in the watermark zones 44. As the pair of rollers 19 continues at its higher rate of feed the sheet 45 which has been torn loose will be transported to the stack 30 of sheets before the front end of the web, which is fed forward with the help of pair of rollers 14, has time to advance to the nip between the pair of rollers 19.

[0013] The sheet 45 produced which has been treated in the above mentioned manner will have around its edge a narrow "watermark zone" and a somewhat irregular edge structure which is reminiscent of that which is found on hand-made paper.

[0014] In certain cases it is not desired to sever the individual sheets from the web 2, but to retain the web. The edge zone 41 of the web may then be provided with holes 42 adapted for a feed by means of toothed wheels. The edge zonewith holes 42 can be used for toothed wheel feed in an arrangement of the type as shown in fig. 1 but it can also be used in conjunction with printouts from automatic printers of the type used in connection with computers. If the guiding is done with the help of the toothed holes in the edge zones of the web 2, a very accurate feed of the web can be obtained and the edge zones 41 are severed in the manner as described earlier in the station II so that after passage of the clamp rollers 23 in the station III they are removed as edge clippings and be dumped into a collecting device 24.

[0015] The arrangement described here is intended only as an example of such an arrangement representing an embodiment of the invention and it is possible, for example, to use instead of the tearing wire 21 a rotating knife or a fixed (blunt) knife edge.

Claims

1. A method for the manufacture of a paper web or paper sheets with decorative edge cutting comprising the separation of at least one edge portion of a paper web whilst at the same time a decorative, irregular edge structure is imparted to thecuter lateral edge of the web formed by the separation characterized in that the paper web is compressed in the separating zone by means of co-operating rollers, whereupon the web is conducted over a roller comprising a cutting or tearing device
which is located so that it is made to engage with the said compressed region of the web when the same is led over the roller and that the web,when it is led past the cutting or tearing device <is broken up in its longitudinal direction.

2. A method in accordance with claim 1, characterized in that the paper web is provided with longitudinal and transverse dandy roller marks or watermarks in narrow edge zones, the said compression of the paper web as well as the said separation of the paper web being carried out in these edge zones.

3. A method in accordance with claim 1, characterized in that the said compression of the separating zones is carried out by means of a tool with convex working surface.

4. A method in accordance with claim 3, characterized in that the said tool has a v-shaped cross-section with rounded front portion.

5. A method in accordance with claim 1, characterized in that the compression of the said longitudinal edge zones is carried out with the help of at least one rotating roller which is provided with annular ridgelike portions arranged around the periphery of the roller and that the hold-on roller is constituted of a plain roller with hard surface, e.g. a steel roller.

6. A method in accordance with claim 1, characterized in that the compression of the said transverse edges is carried out by means of a rotating roller with straight ridgelike portions arranged axially on the surface of the roller and that the hold-on is constituted of a plain roller with hard surface, e.g. a steel roller. -

7. A method in accordance with claim, 1, characterized in that the web is divided into sheets by the web,with cut edge and provided with transverse compressed zonesbeing conducted between two individually driven pairs of rollers arranged at a distance from one another, the first pair of rollers being driven at a constant peripheral speed whilst the second pair of rollers is driven at varying peripheral speed in such a manner that the end of the web delivered from the first pair of rollers is made to engage with the second pair of rollers which at the time is at a lower peripheral speed than the first pair of rollers, a so-called slack arising as a result on the part of the web situated between the pairs of rollers, whereupon the peripheral speed of the second pair of rollers is made to increase so that the part of the web between the said pairs of rollers is stretched and is subjected to a tensile stress of such a magnitude that the compressed transverse portion which is situated between the pairs of rollers is forced to break, producing an individually separated sheet which as it is engaged by the second pair of rollers is delivered at a faster rate than the rate of feed of the web which is fed forward by the first pair of rollers.

8. An arrangement for the implementation of the method in accordance with claim 1, characterized in that the cutting arrangement is constituted of a stationary, thin wire which is arranged in a groove or a recess in the roller co-operating with the roller, the wire being arranged in such a manner that it is inclined in respect of the tangent of the roller surface in the point of cut between wire and roller surface and that the wire is arranged right-angled to the axle of the roller.

Drawing