Abstract:
A device for folding a multi-sheet paper article that includes conveyor means for conveying the paper article in a direction of conveyance (F 1 ), folding members for pushing the paper article to the conveyor means, guides, which are arranged on either side of the folding members for enveloping the paper article around the folding members, wherein the folding members define folding ridges which, as seen in the direction of conveyance, run side by side and thereby in the direction of conveyance define a gap between the folding ridges. Therein, as seen in the direction of conveyance, a width (b, b′, b″, b″′) of the gap between the folding ridges progressively narrows.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention pertains to the field of processing paper articles, in particular print shop products. The invention relates to a device and a method for folding a planar product, in particular a paper article, as well as a folded paper article according to the preamble of the corresponding independent claims. 
         [0003]    2. Description of Related Art 
         [0004]    One such device and a method are, for example, disclosed in DE 28 42 226 (corresponding to: U.S. Pat. No. 4,265,437): a multi-sheet newspaper, which is shown with a transverse break, is folded with a further longitudinal fold, wherein at one inner fold a counter kink or counter fold is created, which comprises a curvature, resp. a flexion, which is contrary to the curvature of the fold to be created (on the outer side). To this end, the device comprises multiple pairs of coaxial folding presses, at the circumference of each of which a folding ridge is formed and which are separated from one another by a space. The folding presses push upon the product, during which it is folded against the folding presses, wherein the counter kink is formed in the space between the folding presses. It is seen, however, that the method in the case of specific circumstances, for example with thick, multi-sheet products, that overloading may occur in the area of the inner side of the fold. It, thus, arises that as is shown schematically in  FIG. 1 , un-defined and uncontrollable creases can occur which radiate like spokes from the crossing point of the last fold (often called “Post-fold”) and the penultimate fold (often called the “transverse break”). 
         [0005]    EP 0 413 371 B1 discloses different variants of pressure rollers by which a printed product is folded. In an embodiment one such roller is powered, to which end a groove is formed in the roller, in which a drive belt lies. Hence between the folding ridges at the circumference of the roller, a gap exists (thus the groove for the drive belt), this is however not provided to generate a counter-fold ( FIG. 11 ). In another embodiment the roller is not driven and also features no groove ( FIG. 12 ). 
         [0006]    DE 23 30 513 shows a folding group in which a product is folded by a belt which is conveyed along a row of rollers and moves with the product in the direction of conveyance. The belt runs along the whole area in which the product is bent. A counter-fold is not intended. 
         [0007]    DE 571 796 discloses a device for folding sheets by means of bending the half-sheets. Profiled rollers are present to hold down the sheets. An angle of the profile of this roller matches along the direction of conveyance with the diminishing angle between the sheet halves. A counter-fold is also not intended here. 
         [0008]    EP 0 415 077 shows a folding device which generates, in a sheet material, a first fold in its direction of movement and a second fold in the transverse direction. Adjacently via an arrangement of belts a third fold is made, again in the direction of movement, wherein the sheet material moves through the folding device continuously and without stopping. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    It is therefore an object of the invention to create a device and a method for folding a planar product, in particular a paper article of the kind mentioned above, which eliminates the disadvantages mentioned above. A further object is to prepare a corresponding cleanly folded paper article. 
         [0010]    This object is achieved by a device and a method for folding a planar product, in particular a paper article, as well as a folded, in particular multi-sheet, paper article with the characteristics of the corresponding independent claims. 
         [0011]    The device for folding a planar product, in particular a paper article, thus comprises:
       conveyor means for the conveyance of the paper article in a direction of conveyance F1,   a folding member for pressing the paper article to the conveyor means,   guides, which are arranged on either side of the folding member, for enveloping the paper article around the folding member,   wherein the folding member defines folding ridges, or rather folding ridges are formed on the folding member,
 
Thereby a space between the folding ridges progressively or continuously narrows, as seen in the direction of conveyance.
       
 
         [0016]    As seen in the direction of conveyance, the folding ridges run side by side and thereby define a gap formed in the direction of conveyance between the folding ridges. The gap thus comprises a decreasing width in the direction of conveyance, corresponding to the spacing of the folding ridges. 
         [0017]    In the method, the planar products, in particular paper articles are conveyed through the middle of the device and enveloped around the folding member, wherein a longitudinal fold is formed. In the gap between the folding ridges a counter-fold forms, with a curvature opposite to the curvature of the longitudinal fold. Through gradual squeezing-together of material which borders on the counter-fold, by means of the folding ridges which are arranged with a narrowing space (or rather the width of the gap) relative to one another the counter-fold is pressed into the gap in accordance with the enveloping of the paper article, and is pressed substantially flat. 
         [0018]    The formation of the counter-fold thus occurs in a controlled manner. The folding conserves the folded product (material and, where appropriate, printed layout), and the products are easier to open on account of the better-defined folding. Thanks to the clean folding, the products also appear to be of higher quality. Moreover, by means of the invention it is possible to fold thin as well as thick products without requiring that the device first be adjusted. 
         [0019]    It is possible to fold, with the device, both single products as well as a copy stream of paper products, in particular print shop products, as appropriate with a leading folded edge being the transverse fold. 
         [0020]    Preferably, in the area of a transverse fold, a counter break or a notch is formed, in which the counter-fold merges into a counter-break valley fold which proceeds to the transverse fold. The counter-break valley fold runs in particular to an actual inflection point of the transverse fold, at which the outer part of the newly-formed longitudinal fold meets the transverse fold. 
         [0021]    A standing unit for enveloping the paper articles around the folding member preferably features two guide elements which are arranged mirror-symmetrically about a central plane, which form guide surfaces for the enveloping of the paper articles. The guide surfaces wind approximately helically about a line which runs parallel to the future folded edges. In the area of the future folding ridges. In the area of the future folded edges, the objects are fixed by a pressure device between mutually cooperating pressure elements which function as folding members. The folding members are preferably also a part of the conveyor device and can serve for driving in the direction of conveyance. The pressure elements feature, for example, pressure rollers and folding rollers, which press the products in the area of the future folded edge against a counter element. This counter element is, for example, a driven circulating belt. The rollers are typically arranged in the middle plane of the standing unit and are turnable about an axis which is normal to the middle plane. Translatory displacements in a direction perpendicular to the direction of conveyance are possible for adjustments to the thickness of the products, wherein to this end the rollers elastically deform and are pushed back against the counter element by tension. The rollers are substantially stationary in a direction parallel to the direction of conveyance. 
         [0022]    The folding rollers each have respectively two peripheral edges which function as folding ridges, which are separated from one another by the gap. Folding rollers which succeed each other in the direction of conveyance comprise a gap which narrows monotonically from roller to roller. 
         [0023]    In other preferred embodiments of the invention, the folding members are not rollers, but rather belts which travel over deflection rollers and run along the ridge folds to the counter fold. 
         [0024]    The folding rollers can be designed as single pieces, or multi-pieced. The material of the folding rollers can be a metal (steel, brass, aluminum, . . . ) or a hard plastic, or a combination of different materials can be used. 
         [0025]    In another preferred embodiment of the invention, the folding rollers each comprise two roller halves, which respectively are turnable about a common axis, wherein the axes of the two roller halves are not coaxial, but rather (slightly) inclined with respect to the normal of a middle plane of the device. The roller halves are, thus, slightly skewed about an axis which runs in the middle plane and perpendicular to the conveying surface. In this way, a narrowing space (b, b′, b″, b″′) and respectively a tapering gap is formed between the peripheral edges of the two roller halves in the contact area of the roller pairs with the product. This matches the direction of the ridge fold to the counter fold. 
         [0026]    The folded paper article is in particular a print shop product, preferably multi-paged, and comprises a transverse fold and a longitudinal fold executed subsequent to the transverse fold, in which at the inner side of the longitudinal fold an inner portion of the sheets is folded with a curvature contrary to the curvature of the longitudinal fold and a counter fold is formed. To this end, a notch or a counter break is present in an area between the transverse fold and the counter fold, in which the counter fold merges into a counter-break valley fold which continues to the transverse fold. 
         [0027]    Further preferred embodiments of the invention arise from the dependent claims. To this end, characteristics of the method claims can be freely combined with those of the device claims, and vice-versa. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    In the following the subject of the invention is described in more detail with reference to preferred embodiments which are depicted in the included drawings. Schematically are shown: 
           [0029]      FIG. 1  a paper article folded according to the state of the art; 
           [0030]      FIGS. 2   a - 2   c  views of a paper article folded according to the invention; 
           [0031]      FIGS. 3   a - 3   f  a folding device according to the invention. 
       
    
    
       [0032]    As a matter of principle, like parts are given the same reference numerals in the figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The  FIGS. 2   a ,  2   b  and  2   c  show different views of a paper article folded according to the invention, in the following also called product  2 .  FIG. 2   a  shows schematically a view of a product  2  which has been partially opened again after being folded along a longitudinal fold  12 . For the sake of a better representation, the folds on the inner side of the longitudinal fold  12  are depicted larger than they would occur in a typical product  2 , for example in a folded newspaper. 
         [0034]    The folded product shown is formed by folding at a transverse fold  13  and through subsequent folding at the longitudinal fold  12 . Before the folding at the transverse fold  13 , there can already be a first longitudinal fold (not shown here). In the folded product  2  two product halves are folded upwards at least approximately in the middle at the longitudinal fold  12 . The product  2  lies symmetrically to a middle plane which runs through the longitudinal fold  12 . 
         [0035]    A lower, outer portion of the multiple sheets of the product forms a ridge fold as an outer part of the longitudinal fold  12  (not visible in  FIG. 2   a , but see  FIGS. 3   c - 3   f ). As seen along the longitudinal fold  12 , roughly between its middle and the end which meets the transverse fold  13 , an upper, inner portion of the sheets is folded upwards and forms a counter fold  14 . This forms a peak fold, its curvature is contrary to the curvature of the curvature of longitudinal fold  12  as a whole. Material planes which are adjacent to the counter fold  14  merge into the valley fold  15  of the counter fold  14  in the un-folded area of the inner side of the product. 
         [0036]    At one side of the product  2 , according to the material, thickness and size of the product  2 , the counter fold  14  terminates at an endpoint  16 , as it there meets its associated valley fold  15  at an acute angle. In the example of  FIG. 2   a , at the opposite side of the product  2 , a transverse fold  13  is present. At the transition of the counter fold  14  to the transverse fold  13 , a so-called counter break is present, this means that the counter fold  14  (which is a peak fold), is transformed at a corner  17  into a valley fold, in the following called a counter-break valley fold  19 . The counter fold  14  and the counter-break valley fold  19  both lie in the middle plane. The counter-break valley fold  19  forms a transition between counter fold  14  and transverse fold  13 . Counter-break peak folds  18  are present on both sides of the counter-break valley fold  19 , which radiate from the corner  17 , and which respectively form a transition between a plane adjacent to the counter fold  14  and a plane adjacent to the counter-break valley fold  19 . The two counter-break peak folds  18  transition to the transverse fold  13  each at a respective counter-break kink  20 . 
         [0037]    If the sections of the transverse fold  13  in the two product halves which are folded against each other are imagined to extend, they would intersect the transverse fold at an ideal inflection point  22 . Were the product to consist of a single sheet, then this would be the actual inflection point. However as a consequence of the product&#39;s thickness from the lower portion at the outer part of the longitudinal fold  12  to the upper portion which is folded into the counter fold  14 , the length of the materials between corner  17  and the end of the counter-break valley fold  19  (at transverse fold  13 ) does not reach the ideal inflection point  22  of the transverse fold. The actual inflection point  21  of the transverse fold is thus somewhat pulled into the product  2  during folding, and is displaced from the ideal inflection point  22  by a difference or a space d. Depending on the properties of the product, the space amounts to more than one millimeter or more than two millimeters. Thereby segments  23  of the transverse fold  13 , which lie between the actual inflection point  21  and the two counter break kink points  20  (in the following called counter break segments  23  of the transverse fold), are also curved or kinked inwards vis-à-vis the remaining segments of the transverse fold. This is further clarified by the side view of  FIG. 2   b  and a corresponding detailed view  2   c  of the area A of  FIG. 2   b.    
         [0038]      FIG. 3   a  depicts parts of a folding group  200  according to the invention, namely a conveyor device  202 , a standing unit  210  for standing/folding of the products and a transfer unit  220  for further conveyance of products. The products themselves, an example press unit for pressing the folds and a depositing device for turning the folded, vertically standing products to a horizontal position are not shown. 
         [0039]    The conveyor device  202  serves for conveying the products to be folded through the folding group  200 . It features several sub-conveyors: 
         [0040]    A first sub-conveyor  201  comprises a driven belt  204 , which is wrapped around several rollers  203 . The active run of the belt  204  defines a narrow conveyance surface, on which the products lie in the area of their future folded edge and are moved in direction of conveyance F 1 . The longitudinal fold  12  that is formed in the product thus lies parallel to the direction of conveyance. In the example shown, the belt  204  comprises curved gearing to maintain its centered position on the rollers  203 , as can be seen on one of the rollers  203 . 
         [0041]    The products are pressed against the belt  204  by means of press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ′″. This is stabilized from below by further rollers or supporting rollers  206 . The supporting rollers are preferably arranged so that they respectively each correspond to a folding roller, i.e. that they lie opposite to the folding rollers with respect to the belt, wherein in each case a supporting roller lies across from a folding roller. 
         [0042]    Belt  204 , supporting rollers  206  and press rollers  3  form a pressing device  207  for fixing the future folded edges. The belt  204 , and respectively the conveyance surface, can comprise a groove into which the products are pressed by the folding member. The press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ″′ are mounted to holding means  216  about axes  215  which run perpendicular to the direction of conveyance F 1 . This allows a resilient yield of the press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ″′ upwards, against gravity and/or a spring force (with pre-tension) yet without any substantial movement of the press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ″′ in the direction of conveyance. Preferably, in each case two press rollers  3  are mounted in a single bearing body  218  which is mounted on a swivel axis  217  (which runs parallel to the axes  215  of the press rollers  3 ) and is moveable relative to the holding elements. The design of the press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ″′ is described in more detail below in conjunction with  FIGS. 3   b - 3   f.    
         [0043]    A second sub-conveyor  222  is integrated into the transfer unit  220  for the standing conveyance and guidance of the pre-folded products. It features a plurality of belts  221  looped around rollers  223 , which are driven in opposing pairs. Between these a vertical conveyance gap for the products is formed. The rollers have a sprung support  224 , such that the conveyance gap has a variable width. The second sub conveyor  222  is coupled with the drive for the first sub-conveyor  201  via a coupling element  225 , here a further belt. 
         [0044]    The standing unit  210  features two planar guide elements  212  arranged beside the belt  204 , of which only one is shown here. The guide elements  212  are mirror-symmetric to a middle plane of the folding group  200 , which is, as a rule, vertical. The guide elements function together in the manner of a folding funnel. They thus serve to bend the product halves of a product  2  upwards and toward one another on both sides of the fold  12  to be produced. Thereby, the longitudinal fold  12  of a product  2  is formed on the conveyance surface and in the direction of conveyance F 1 , and a middle plane of the product  2  lies in the middle plane of the folding group. At the entrance of the folding group  200 , the guide faces  213  lie in the horizontal plane of conveyance and change their orientation as they travel further along, as they rise upwards and come together in a v-form. The guide faces  213  wind helically about a line which runs parallel to the future longitudinal fold  12 . 
         [0045]    Between the two guide elements  212  is a gap, in which the above-described pressure device  207 , or as the case may be, the first sub-conveyor  201  operates. 
         [0046]    The folded product  2  at the exit of the standing unit  210  is subsequently transferred to a transfer unit  220  and from its local sub-conveyor  222  further conveyed in a controlled manner in a vertical conveyance plane (middle plane), i.e. standing. The products  2  are transferred to a press unit in their standing position or as the case may be taken thereby in a controlled fashion. 
         [0047]      FIGS. 3   b - 3   f  show in the direction of conveyance successively following press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ″′, as well as their effect on the products  2 .  FIG. 3   b  shows a press roller  3  of a first roller set, which is surrounded by a press belt  4 . The press belt  4  is shown as a round belt, but can also comprise a different form, for example a wedge or v-form. The press roller  3  of the first roller set pushes the products  2  against the belt  204 , as preparation for the successive folding. The press belt  4  is made of an elastic material and thereby stabilizes irregularities in movement and position of the products  2 . 
         [0048]    The press belt  4  can also, as shown by dotted lines in  FIG. 3   a , not only run and be guided over the press rollers  2  but also over one or more of the folding rollers  5 ,  5 ′,  5 ″,  5 ″′. This improves the guidance of the products  2  and the synchronicity of the products  2 : jolts are reduced or eliminated, the clamping between the press belt  4  and the belt  204  is improved. 
         [0049]      FIGS. 3   c - 3   f  show folding rollers  5 ,  5 ′,  5 ″,  5 ″′ with a gap that narrows in the direction of conveyance F 1 . The gap lies in each of the folding rollers  5 ,  5 ′,  5 ″,  5 ″′ between two peripheral edges  6 ,  6 ′,  6 ″,  6 ″′ of the folding rollers. In the  FIG. 3   a  not all of the folding rollers are shown with reference numerals and are associated with the  FIGS. 3   b - 3   f.  The unspecified folding rollers comprise, preferably, a gap which in each case lies between that of the preceding roller and that of the subsequent roller. It can be, however, that immediately successive rollers comprise the same gap width. 
         [0050]    The creation of the counter fold occurs as can be seen in the  FIG. 3   c , substantially as described in the above-mentioned DE-C 28 42 226, which is here included by reference in its entirety. As the product  2  is folded against the folding member, thus in the depiction upwards against the folding roller  5 , the gap between the peripheral edges  6  allows that an overlaying part of the product  2  can yield upwards into the gap. In the figures, the product  2  is depicted schematically by two sheets, in reality however, the invention is appropriate for substantially bulky paper articles and can be used for dozens to hundreds of sheets which lie on top of one another and are to be folded together. If the product comprises a transverse fold  13 , it enters into the folding group  200  as the leading edge. 
         [0051]    The creation of the counter break in the counter fold occurs as follows: in contrast to DE-C 28 42 226, in which successive folding rollers comprise the same gap width as the first folding roller  5 , here the gap narrows noticeably in successive folding rollers  5 ′,  5 ″,  5 ″′ ( FIGS. 3   d - 3   f ), in accordance with the folding of both product halves. In this way the valley folds  15  of the counter fold  14  are folded towards one another (in a direction perpendicular to the direction of conveyance), and the counter fold  14  itself is pressed further together and upwards. The surfaces (depending on the material) between valley fold  15  and counter fold  14  are brought together rapidly and in a well-defined manner until they are nearly parallel. They form precise, sharp edges of the valley fold  15  and by the counter fold  14 , in particular after the pressing of the folded product  2  in the subsequent press unit. 
         [0052]    As a rule a transverse fold  13  is present in the product  2 , as shown in  FIG. 2   a , whereby the cross section through the product  2 , as shown in the  FIG. 3   f , can not be valid in the area of the transverse fold  13 . The material of the product must also run in the area of the newly-formed longitudinal fold  12  around the transverse fold  13 . It turns out that on this account that in the course of folding ( FIGS. 3   c - 3   f ) the material in the area of the transverse fold automatically kinks, i.e. forms the counter break. The counter fold  14  thus devolves at the corner  17  into the counter-break valley fold  19 , which runs to the transverse fold  13 . 
         [0053]    Because the corner  17  is folded upwards and thereby separated from a lower part of the longitudinal fold  12  which lies upon the belt  204 , and because the length of the counter-break valley fold  19  cannot be increased by stretching the paper, the transverse fold  13  is pulled inward at the end of the counter-break valley fold  19 . In this way, the difference d develops between the ideal inflection point  22  of the transverse fold  13  and the actual inflection point  21  of the transverse fold  13 . In this way the counter break segment  23  of the transverse fold  13  also develops between the two counter-break kink points  20  and the actual inflection point  21  of the transverse fold  13 . 
         [0054]    The run-in of the valley folds  15  of the counter fold  14  (at the end point  16  of the counter fold) into the counter fold  14  is a consequence of the fact that the product  2  is somewhat thicker at the side of the transverse fold  13  than at the opposite side, due to the stiffness of multiple layers of paper. As the product is run through the folding rollers  5 ,  5 ′,  5 ″,  5 ″′ the pressure on the inner paper layers decreases in the thinner part of the product, and the need of forming these inner paper layers to the counter fold  14  decreases. Consequently the counter fold  14  is shallower and smaller as it runs to the end point  16 . Depending on the dimensions and properties of the materials, the counter fold  14  can, however, not run out until it reaches the opposite side. 
         [0055]    The depicted press rollers  3  and folding rollers  5 ,  5 ′,  5 ″,  5 ″′ are not driven, and turn with the driven belt  204 . In other preferred embodiments of the invention some or all of these rollers can be driven.