Device for perforating material webs

A perforating tool for perforating single or multiple layer material webs or sheets ( 1 ) that are separated therefrom, including a first half ( 16 ) and a second half ( 17 ). In a first half ( 16 ), a multiplicity of perforating teeth ( 15 ) is accommodated; in the first half is also located a tool-free gap ( 18 ). In the second half ( 17 ) of the perforating tool ( 15 ) is a cutting zone ( 19 ) as well as groups ( 22 ) of perforating elements that are configured in alternating sequential fashion, which are angled with respect to the perforating tool.

DETAILED DESCRIPTION From the representation in FIG. 1 can be seen more clearly the lateral displacement of individual sheet layers of a multilayer sheet on the open side of the folded sheet, the displacement occurring when the sheet is folded. Sheet 1 to be folded, depicted in FIG. 1 , is aligned with respect to a reference line 2 . Situated at reference line 2 is closed end 3 of sheet 1 to be folded, of which in representation 1 only the exterior sheet layer is depicted. Reference numeral 4 designates the interior side of the folded spine created at closed end 3 of sheet 1 to be folded. The exterior layer of sheet 1 to be folded, i.e., upper open side 6 , is turned back at exterior curvature radius 8 , whereas lower open side 7 of folded sheet 1 is turned back at a smaller curvature radius 9 . As a result of different radii 8 and 9 on sheet 1 , there is a displacement 10 at open end 5 of sheet 1 , which is caused by the displacement of upper open side 6 relative to lower open side 7 . This effect is more pronounced, the more layers the sheet to be processed contains. The representation according to FIG. 2 depicts in greater detail the top view of a sheet to be folded, on one half of which the incisions to be created according to the present invention are configured for adjusting the shearing stress. Sheet 1 to be folded, according to the representation in FIG. 2 , is depicted in its unfolded state 11 , arrow 14 indicating the direction in which a displacement 10 will arise at open end 5 of sheet 1 to be folded, resulting from the displacement of upper open side 6 with respect to lower open side 7 of multilayer sheet 1 . Whereas along folded edge 12 a perforation pattern 13 is created made up of point-shaped perforation openings, the area of folded edge 12 , running underneath depicted arrow 14 designating the directions of displacement, has a perforation pattern 13 which is characterized by incisions that are slanted with respect to the center of the sheet. The individual incisions all run towards the center of unfolded sheet 11 and make possible a shearing stress adjustment in the area of folded edge 12 of the sheet. The representation according to FIG. 3 depicts a top view of a first embodiment variant of the perforating tool proposed in accordance with the present invention, in the form of a perforating knife. Perforating tool 15 , seen depicted in FIG. 3 , can be divided into two halves 16 and 17 with respect to an imaginary center line represented by a dotted line. The configuration of first half 16 of perforating tool 15 is characterized by a regular sequence of perforating teeth 28 acting in pointwise fashion on the folded spine in this area, the perforating teeth being arranged in continuous repetition 35 over the length of first half 16 . Perforating teeth 28 , acting in pointwise fashion upon the folded spine of a multilayer sheet, introduce in folded spine 1 openings through which air can escape that is trapped in the folded spine, puffing out the spine, so that even in the case of multilayer sheets a folded spine can be produced that is free of trapped air. Adjacent to the continuous sequence of perforating teeth 35 in first half 16 of perforating tool 15 is a tool-free area 18 . Tool-free area 18 makes it possible to create a material bridge in the center of a multilayer folded sheet. The material bridge, which is generated on first half 16 of perforating tool 15 in accordance with the selected depth of tool-free gap 18 , stabilizes the folded spine of the multilayer sheet in the area of its center. In second half 17 of perforating tool 15 , proposed in accordance with the present invention, a cutting zone 19 is configured. Cutting zone 19 is immediately adjacent to tool-free gap 18 in first half 16 of perforating tool 15 , and it extends to a first group 22 of slanted perforating elements. Using cutting zone 19 , a partial incision is produced in the folded spine adjacent to the material bridge generated in the multilayer sheet by tool-free gap 18 . Adjacent to cutting zone 19 , which extends continuously, is a first group 22 of slanted perforating elements. Behind first group 22 of slanted perforating elements, which are preferably configured as longitudinal slits of perforating tongues that are separated from each other, is a straight segment 21 , which is configured as a cutting knife. Cutting knife area 21 and groups 22 of slanted perforating elements are accommodated in alternating sequential fashion in second half 17 of perforating tool 15 , configured in accordance with the present invention. The perforating knife configured according to the present invention extends over a width 38 which advantageously corresponds to the maximum material web format to be processed. Depicted in FIG. 3 above the side view of perforating tool 15 that is configured according to the present invention is a top view both of straight cutting edges 21 as well as of groups 22 of slanted perforating elements, arranged in alternating sequential fashion between them, the perforating elements advantageously being configured as perforating tongues. From the center line, depicted as a dotted line, extending to first group 22 is an elongated cutting zone 19 . The height of perforating tool 15 according to the representation of FIG. 3 is characterized by reference numeral 20 , it being possible to accommodate perforating tool 15 , so as to be replaceable, on lateral surfaces of perforating cylinders, for example, in folding apparatuses that process material webs. In this way, perforating tools, which are subject to a high degree of wear, can be replaced very rapidly and simply, so that the perforations on multilayer material webs can be generated in the required quality and precision. In the representation according to FIG. 4, a group of slanted perforating elements is depicted in greater detail. The top view depicted in enlarged dimensions in FIG. 4 of a group 22 of perforating elements—preferably perforating tongues—includes a first perforating tongue 22 . 1 , a second perforating tongue 22 . 2 , and a third perforating tongue 22 . 3 . The individual perforating tongues are separated from each other by longitudinal slits 25 , which can act to lead away the paper dust arising during the perforating, so that it can be removed from the perforating area without accumulating. Adjacent to three perforating tongues 22 . 1 , 22 . 2 , 22 . 3 is a straight segment 21 that is also separated by a longitudinal slit 25 , the upper edge of the segment being configured as a straight cutting edge. In addition to the embodiment depicted in FIG. 4 of a group 22 of slanted perforating elements having three perforating tongues, it is possible within one group 22 of perforating tongues on second half 17 of perforating tool 15 to have, for each group 22 , only two or also a larger plurality, i.e., four or five, individual perforating tongues, separated from each other by longitudinal slits 25 . The perforating tongues run to a point 26 , which is a part of a surface 23 that is formed so as to be slanted. Upon contact with the multilayer material web to be perforated, perforating tongue points 26 first meet the uppermost layer of the material web acting in pointwise fashion, so that the incisions produced by the perforating tongues in the direction of the center of the sheet to be folded or to be perforated end up having a length that is a function of the thickness, i.e., the number of layers of the individual material webs. The thicker the material webs to be folded or to be perforated, i.e., the more layers the sheet to be perforated contains at the folded spine, the longer the incisions will have to be configured on the sheet in one half of the folded spine in accordance with perforating pattern 13 . The incision length is a function of the penetration depth into the multilayer material web of slanted surfaces 23 of perforating tongues 22 . 1 , 22 . 2 , 22 . 3 in second half 17 of perforating tool 15 , configured in accordance with the present invention. From the representations according to FIGS. 5 . 1 through 5 . 4 , alternate embodiments of second half 17 of perforating tool 15 , configured according to the present invention, are depicted in greater detail. From the representation according to FIG. 5 . 1 , it can be seen that in second half 17 of perforating tool 15 individual groups 22 of slanted perforating tongues are configured. In this embodiment, groups 22 of slanted perforating elements include only two perforating tongues 22 . 1 and 22 . 2 . Individual perforating tongues 22 . 1 and 22 . 2 are separated from each other by longitudinal slits 25 and are uniformly angled with respect to a rotational axis 31 , which coincides with reference line or longitudinal axis 37 on perforating tool 15 , i.e., on front edge 22 . 5 and on rear edge 22 . 4 at angle of inclination 24 with respect to the plane of perforating tool 15 . Angle of inclination 24 , at which the perforating tongues are angled with respect to the plane of perforating tool 15 , is preferably in the range between 20° and 40°. It is particularly preferable that angle of inclination 24 be 30°, the inclination of the front edge of perforating tongues 22 . 1 and 22 . 2 being selected with respect to the center of sheet 1 to be folded. Since in the embodiment according to 5 . 1 both front edge 22 . 5 as well as rear edge 22 . 4 are symmetrically angled from the plane of perforating tool 15 with respect to axis of rotation 31 of each perforating tongue 22 . 1 and 22 . 2 , the term symmetrical slant 32 is also used. Between groups 22 of slanted perforating elements, including in this embodiment only two perforating tongues 22 . 1 and 22 . 2 , are individual cutting segments 21 parallel to reference line or longitudinal axis 37 on perforating tool 15 . Groups 22 of slanted perforating tongues 22 . 1 and 22 . 2 as well as straight cutting segments 21 are positioned in second half 17 of perforating tool 15 in alternating sequential fashion. In the embodiment variant according to FIG. 5 . 2 , an alternative possible embodiment of second half 17 of perforating tool 15 is depicted in greater detail. In this embodiment, groups 22 of slanted perforating tongues 22 . 1 , 22 . 2 , adjacent to elongated cutting segment 19 , are angled at their rear edge 22 . 4 with respect to the plane of perforating tool 15 , whereas front edge 22 . 5 still lies straight in the plane of the perforating tool. In this angle pattern, an off-center displacement 33 of perforating tongues 22 . 1 and 22 . 2 , angled with respect to the plane of perforating tool 15 and configured preferably as perforating tongues, results. Reference numeral 24 designates the angle of inclination, which in a particularly preferred configuration of a perforating tool is 30°. Situated, by analogy to the representation in FIG. 5 . 1 , between individual perforating tongues 22 . 1 and 22 . 2 , and separated by slit-shaped openings 25 , are individual straight incisions 21 , which are also separated from groups 22 of slanted perforating tongues 22 . 1 , 22 . 2 by slit-shaped openings 25 running perpendicular to the plane of the drawing in accordance with the representation in FIG. 5 . 2 . Groups 22 of slanted perforating tongues according to the embodiment variant in FIG. 5 . 2 also include only two perforating tongues. In addition, it is also of course possible to furnish individual groups 22 of slanted perforating elements with three or five or any number of perforating tongues. According to this angle pattern 33 , front edges 22 . 5 of all individual perforating tongues 22 . 1 and 22 . 2 still lie in the plane of perforating tool 15 . Depicted in greater detail in the representation in FIG. 5 . 3 is a further embodiment of the arrangement of groups 22 of slanted perforating elements within second half 17 of a perforating tool 15 configured according to the present invention. Adjacent to elongated cutting segment 19 are groups 22 of slanted perforating elements, which are interrupted in alternating sequence in each case by straight cutting segments 21 that lie in the plane of perforating tool 15 . Reference line or longitudinal axis 37 , in relation to which the perforating tongues are slanted at angle of inclination 24 , is parallel to perforating tool 15 . In the embodiment of the perforating tool according to the representation in FIG. 5 . 3 , rear edges 22 . 4 of the individual perforating tongues, separated from each other by longitudinal slits 25 , lie in the plane of perforating tool 15 , whereas their front edges 22 . 5 , in the top view according to the representation in FIG. 5 . 3 , are slanted downwards. This embodiment also shows an off-center angle 34 of the individual perforating tongues of groups 22 of slanted perforating elements. As a result of this arrangement pattern of straight segments 21 and individual perforating tongues 22 . 1 and 22 . 2 of groups 22 of slanted perforating elements, longer free spaces 36 are formed between rear edges 22 . 4 of individual perforating tongues 22 . 1 , 22 . 2 , the free spaces later forming material bridges in the folded spine of the preferably multilayer folded sheet. From the representation in FIG. 5 . 4 , a further embodiment possibility of second half 17 of perforating tool 15 is depicted in greater detail. This embodiment is characterized by the fact that in second half 17 of the perforating tool, a multiplicity 22 . 1 , 22 . 2 through 22 .n of individual slanted perforating tongues is configured according to a fishbone pattern. The individual perforating tongues arranged in symmetrical slant 32 are interrupted by free spaces 36 . Perforating tongues 22 . 1 through 22 .n are each slanted about their axis 31 both at the front as well as at the rear edge with respect to reference line or longitudinal axis 37 of perforating tool 15 . Here as well, the result is a continuous repetition of perforating tools over half 17 of the perforating knife. All the perforating tongues arranged in continuous repetition are angled with respect to the perforating tool plane about an angle 24 with regard to reference line 37 . The angle of inclination is preferably in the range between 20° and 40°, an angle of inclination of 30° being particularly preferred. Using the embodiment of the perforating tool proposed in accordance with the present invention according to FIGS. 3, 5 . 1 , 5 . 2 , 5 . 3 , and 5 . 4 , it is possible on one half of a folded spine of a folded sheet composed of a plurality of layers to introduce incisions as a function of the strength, i.e., the number of layers of the sheet, the incisions making possible a shearing stress adjustment of the inner sheet layers relative to the outer sheet layers, so that folded spines 4 can be configured overall in a more planar fashion and lateral displacement 10 of the individual layers with respect to each other can be significantly reduced at the open end of multilayer folded sheet 1 . Reference Numeral List 1 sheet 2 reference line 3 closed end 4 folded spine 5 open end 6 upper open side 7 lower open side 8 outer curvature 9 inner curvature 10 displacement 11 unfolded sheet surface 12 folded edge 13 perforation pattern 14 direction of displacement 15 perforating tool 16 first half or section 17 second half or section 18 tool- or perforation-free gap 19 cutting zone 20 height extension 21 cutting segment 22 group of perforating elements 22 . 1 first perforating tongue 22 . 2 second perforating tongue 22 . 3 third perforating tongue 22 . 4 rear edge 22 . 5 front edge 23 slanted surface 24 angle of inclination 25 slit-shaped opening 26 perforating tongue point 27 — 28 continuous perforating teeth 29 center line 30 free space 31 axis of rotation 32 symmetrical angle 33 off-center angle 34 off-center angle front edge 35 continuous repetition 36 free space 37 reference line; longitudinal axis 38 width perforating tool