Abstract:
Signatures that are cross-folded to form cross folded products can be formed without damaging the product whether the cross-folded product is thick or thin. The signatures are given a pre-fold by a pre-fold cylinder that utilizes a plurality of pre-fold gripping element systems. The pre-folded product is carried by the pre-fold cylinder to a pair of folding rollers which finish fold the cross-folded signatures.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method for the transverse folding of signatures as well as to an associated device. This method and device pre-folds signature prior to finish-folding them. 
     DESCRIPTION OF THE PRIOR ART 
     It is generally known to produce transversely folded products wherein a plurality of paper ribbon sections conducted one above the other, and called signatures, are respectively pushed into folding jaws of a folding jaw cylinder by means of folding blades of a folding blade cylinder. 
     Only transversely folded products of up to 96 pages can be produced by means of such folding devices, because otherwise the inner and outer portions of the transversely folded product would be damaged. 
     DE-OS 21 46 013, describes a device for longitudinally folding sheets of paper. Here, sheets of paper are pre-folded between a rotating circle-shaped folding blade and an annular groove of a rotating pre-fold cylinder, and are subsequently finish-folded by means of a pair of belts. 
     DE 41 20 630 C1 discloses a device for transversely folding a web in a rotary printing press. Here, a folding blade cylinder and a folding jaw cylinder are arranged for making a first transverse fold. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is based on providing a method, as well as an associated device for producing a transverse fold. 
     In accordance with the invention, this object is attained by providing the signatures with a pre-fold through the use of pre-fold clamping elements, such as folding jaws. The pre-folding signatures are then conducted to a pair of rotating folding rollers where they are finish-folded. 
     The advantages which can be achieved with the present invention rest, in particular, in that thick folded products of up to 192 pages can be transversely folded with comparatively little force. An exact transverse fold can be exactly determined in that the center of the fold can be exactly defined, particularly since both halves of the signatures are respectively drawn into the pre-fold clamping gap by the same amount of the insertion of the folding blade. Since transverse folding takes place in two stages, pre-folding and finish-folding, the forces respectively required for one folding step are reduced. The lateral faces of the pre-fold product, which are in contact with the pre-fold clamping gap, are handled free of damage because of the employment of cylindrical pre-fold clamping elements of the pre-fold clamping system which are operating in a jaw-like manner. In the same way, the finish-folding of the pre-folded product of up to 192 pages takes place free of damage because of the employment of folding rollers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention is represented in the drawings and will be described in greater detail in what follows. 
     Shown are in: 
     FIG. 1, a cross section through a schematic representation of a folding apparatus in accordance with the present invention; 
     FIG. 2, a cross section through an enlarged schematic representation of a pre-fold clamping element which has just picked up a transversely-folded product; an in 
     FIG. 3, a longitudinal section taken along line III—III in FIG. 1, wherein only one end of a pre-fold cylinder with a central control of the pre-fold clamping element system is represented. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Two longitudinal folding funnels or hoppers  3 ,  4  are arranged between two lateral frames  1 ,  2 , which have a funnel or hopper inlet roller  7 , driven by a motor  6 , on their paper inlet side, all as seen in FIG.  1 . On their hopper outlet side respectively one pair of funnel or hopper folding rollers  11 , located between lateral frames  8 ,  9 , respectively one drawing roller group  12 , as well as transfer rollers  13 , are arranged. These conduct one or several paper ribbons  14 ,  16  via a main drawing roller group  17  to a transverse cutting and transverse folding device  18 , also seated between the lateral frames  8 ,  9 . The transverse cutting and transverse folding device  18  has a known, two-piece, i.e. provided with two cutters  19 , cutting cylinder  21 , which, in turn, operates against a known, five-piece folding blade, grooved strip and point spur cylinder  22 , which is also called a five piece or field transport and folding blade cylinder. This cylinder  22  has, respectively arranged on its circumference, five folding blades and folding blade fixtures  23 , grooved strips  24  and point spur systems  26 . 
     The transverse cutting and transverse folding device  18  furthermore has a rotating body, for example a pre-fold cylinder  27 , with a number n, for example three, five or seven, but preferably five, pre-fold clamping element systems  28 , distributed at even distances over its circumference, which respectively work together with the folding blade fixtures  23  of the cylinder  22 , all as may be seen in FIGS. 1 and 2. 
     Each one of the pre-fold clamping element systems  28  consists of from a number m of two to ten pairs of folding-jaw-like pre-fold clamping elements  31 ,  32 , which pairs of clamping elements  31 ,  32  are arranged in the axis-parallel direction of the pre-fold cylinder  27  next to each other and spaced apart from each other at a clear spacing distance “a”, as shown in FIG.  3  and which operate in a jaw-like manner. 
     Between lateral or end walls  33  of the pre-fold cylinder  27 —only one lateral wall  33  of pre-fold cylinder  27  being represented in FIG.  3 —two shafts  34 ,  36 , for example hollow shafts, are equipped with the pre-fold clamping elements  31 ,  32 . The ends of the shafts  34 ,  36  are seated in the lateral walls  33  of the pre-fold cylinder  27  and are synchronized with each other by means of tooth segments  37 ,  38  fixed on the shaft, or by gear wheels. A torsion bar  39 ,  41  has been inserted into the center of the shaft  34 ,  36 . Respectively, one end of the torsion bar  39 ,  41  is connected with the shaft  34 ,  36 , the other end of the torsion bar  39 ,  41  is fixed in place in a clamping device, not specifically represented. 
     This clamping device for each torsion bar  39 ,  41  is located on the outside of the lateral wall, not represented, which lies opposite the lateral wall  33 . 
     Each pre-fold clamping element  31 ,  32  is embodied with an enlargement at its end near the periphery, as well as on the side which enlargement or lobe is in contact with the pre-fold product, as depicted in FIG.  2 . For this purpose, the shaft  34  has finger-like, spring-elastic or resilient supports  43 , oriented radially in the direction toward the periphery  42  of the pre-fold cylinder  27  and spaced apart from each other at a distance “a”, as shown in FIG.  3 . On its outer end, near the periphery  42  of the pre-fold cylinder, each support  43  has an enlargement or lobe  46 , extending in the axis-parallel direction with respect to the axis of rotation of the pre-fold cylinder  27 . This means that the end of the pre-fold clamping elements  31 ,  32 , acting on the folded product, projects radically outwardly in respect to the support  43 . 
     In the same way, the respective second shaft  36  has spring elastic supports  44 , each with a cylindrical enlargement or lobe  47 . The supports  43 ,  44  with the enlargement or lobes  46 ,  47  respectively operate together as pairs  29  of pre-fold clamping elements. 
     It is also possible to design the supports  43 ,  44  and the associated enlargement  46 ,  47  in one piece. 
     These ends, provided with enlargements, can be used not only with pre-fold clamping elements  31 ,  32 , but also generally in connection with folding jaws. 
     A control arm  49  is located on one of the shafts, for example the shaft  34 , and is fixed against relative rotation on the shaft end which has the clamping point of the torsion bar  39  or  41 . On its end remote from the torsion bar, the control arm  49  has a roller  51 , which runs off on a known control cam track  52  of a control cam  84 , which is fixed in place on the lateral frame  8 , all as shown in FIG.  3 . 
     Axes of rotation  53 ,  54  of the pre-fold cylinder  27 , as well as of the folding blade, grooved strip and point spur cylinder  22  are spaced apart by means of an imagined center line  56 , and the axis of rotation  54  is distanced by means of an imagined central line  57  from an axis of rotation  58  of the cutting cylinder  21 . The folding blade cylinder  22  is surrounded below these central lines  56 ,  57  by paper guide rods  59 , fixed in place on the lateral frame, as may be seen in FIG.  2 . 
     Two folding rollers  61 ,  62  for finish-folding the printed products, which folding rollers  61 ,  62  are resiliently seated in respect to each other between the lateral frames  8 ,  9  and are also a part of the transverse cutting and transverse folding device  18 , are arranged downstream of the pre-folding cylinder  27 . The transport of pre-folded printed products between the pre-fold cylinder  27  and the folding rollers  61 ,  62  takes place by means of two cooperating belt systems  63 ,  64 . 
     The belts of the first belt system  63  are guided on the circumference  42  of the pre-fold cylinder  27  in grooves  66  located between the pairs  29  of pre-fold clamping elements  31 ,  32 , as well as on a portion of the circumference of the first folding roller  61 . The pre-fold cylinder  27  has a secant-like surface portion  67  as seen in FIG. 2 compared to the periphery  42  of the remainder of cylinder  27 , with this secant-like surface portion  67  extending in an axis-parallel direction, respectively at those locations of the grooves  66  of the pre-fold cylinder  27  at which a pre-fold clamping element system  28  is located. Between the closed pairs  29  of the pre-fold clamping elements  31 ,  32  this secant-like surface  67  has a depth “t”, which is greater than twice the radius r of the enlargements or lobes  46 ,  47  formed on the outer ends of the finger-like spring elastic supports  43 ,  44 . 
     Also, respectively one secant-shaped surface  77 , extending in an axis-parallel direction to the axis of rotation of the transport and folding blade cylinder  22 , is provided on the circumference  76  of the transport and folding blade cylinder  22  at the place where folding blades  23  are arranged. 
     By means of belt guide rollers  68 , the second belt system  64  is conducted above, and at the side of the pre-fold cylinder  27  partially around the pre-fold cylinder  27 , as well as around the second folding roller  62 . Both belt systems  63 ,  64  act together. 
     The clear distance between the two folding rollers  61 ,  62  can be set in accordance with the thickness of the transversely folded product by means of a known folding roller gap adjustment device  74 . Therefore, both folding rollers  61 ,  62  are resiliently seated against each other in a known way in order to temporarily compensate, without damage, a thickening of folding products, for example after the change and the connection of paper webs. 
     Paper guide rods  70 , fixed in place in the lateral frames, are arranged above the cylinders  22 ,  27  between the entry of the paper ribbons  14 ,  16  and the second belt system  64 . 
     A known paddle wheel  69  with a known ejection system  71  for printed products, for depositing the transversely folded products on a delivery belt  72 , is arranged below the folding rollers  61 ,  62  in the lateral frames  8 ,  9 . A guide belt  73 , located at the side of the paddle wheel  69  in the vertical direction, is arranged upstream of the delivery belt  72 . 
     The opening width of the pairs  29  of pre-fold clamping elements  31 ,  32  can be adjusted by means of the shape of the control cam track  52 . 
     For the purpose of setting the product thickness of the signatures  78  which are to be pre-folded, the control cam track  52  has a width f, viewed in cross section in the axial direction, which corresponds to several times the width g of the roller track. In cross section, i.e. across a width of the control cam  84 , the control cam track  52  has a rise, which increases in the direction toward the lateral frame  8 . Accordingly, the control cam  84  is embodied in the shape of a truncated cone and is arranged to be displaceable in the axial direction E of the pre-fold cylinder  27 . The control cam  84  has a centered bore and is laterally fastened on a sleeve-shaped control cam support  86 , wherein an interior diameter of the centered bore and an interior diameter of the control cam support  86  are equal, and both elements  84 ,  86  are preferably made as one piece, as may be seen in FIG.  3 . 
     The control cam support  86  is arranged coaxially with the control cam  84  on a bearing bushing  87 , which is fixed in place on the lateral frame, and which, in turn, receives in its interior a shaft journal  88  of the pre-fold cylinder  27 , seated in a roller bearing  89 . On its surface  91 , the sleeve-shaped portion of the control cam support  86  has an exterior thread  92  and is seated, fixed against relative rotation, axially displaceably on the control cam support  86  by means of a feather key  93 , for example. 
     A sleeve  94  with an interior thread, and which is connected as one piece with a guide ring  96  on the side close to the lateral frame, is in engagement with the exterior thread  92  of the control cam support  86 . The guide ring  96  is rotatably supported with its inner running surface on the surface  91  of the control cam support  86 , and is secured against axial displacement, for example by means of a two-piece holding ring  97 , which is fixed in place on the lateral frame and engages an annular groove  99  circumscribed in an outer surface  98 . 
     On its outer surface  98 , the sleeve  94  with the interior thread has teeth  101  which are connected, for example by means of a toothed belt  102 , with a toothed disk  103  of a motor  104 , fixed in place on the lateral frame, all as may be seen in FIG.  3 . An angle encoder  106  is connected, fixed against relative rotation, with the motor  104 . 
     If it is now intended to change the pre-fold clamping gap  81  because of the different thickness of another folded product, the sleeve  94  with the interior thread is rotated by means of the drive  104  to  101 , so that, by means of this rotation of sleeve  94 , the control cam support  86  is moved in the axial direction E. If the roller  51  now rides on the control cam track  52  in another, for example a higher, position than represented in FIG. 3, the width of the pre-fold clamping gap  81  is reduced. 
     Instead of the running surface of the control roller  51  being crowned, when viewed in cross section, it can also be designed in the form of a truncated cone and thus can adapt itself to the rise in the control cam track  52 . In this case, the rise of the control cam track  52  corresponds to the amount of the stroke of the control roller  51 . 
     With this, it is also possible to adjust the width of folding jaws in folding jaw cylinders. 
     In accordance with a second preferred embodiment, the control cam track  52  can also be arranged fixed in place on the lateral frame, and the control arm  49  supporting the roller  51  can be adjustable in the axial direction on the spindle, or respectively the torsion bar  41 . However, it is essential that the control cam track  52 , which is inclined in respect to the axis of rotation  53  of the pre-fold cylinder  27 , is arranged displaceably in relation to the cam roller  51 . 
     In accordance with another preferred embodiment, the roller  51 , which is located on the control arm  49  and whose axis of rotation  108  extends at right angles in respect to the longitudinal axis of the control arm, can also run off on a control cam track which, viewed in cross section, is level and extends in the axial direction  53  of the pre-fold cylinder  27 . A second cylinder-shaped roller in the form of a support roller and located on the control arm  49 , whose axis of rotation extends in the longitudinal direction of the control arm  49 , rolls off on an exterior  107  of the lateral wall  33  of the pre-fold cylinder  27  with an appropriate radius around the axis of rotation  53  the arrangement is not represented in the drawings. 
     The cylindrical support roller is used as force support of the axial forces generated by the control cam. 
     A method for transversely folding signatures in accordance with the present invention progresses as follows: 
     Signatures  78  are cut from the paper ribbons  14 ,  16 , which paper ribbons  14 ,  16  are conducted above each other, on the folding blade, grooved strip and point spur cylinder  22  with the cooperation of the cutting cylinder  21 , and are respectively grasped at their front edge of a leading element  79  of the signature  78 , pointing in the running direction B of the cylinder  22 , by means of the point spur or other gripper system  26 , and are conducted to a pre-fold clamping system  28  of the pre-fold cylinder  27 . In the process, each signature  78 , collected or uncollected, is pushed into a pre-fold clamping gap  81  of the pre-fold clamping element system  28  by means of a folding blade  23  located on the cylinder  22  as seen in FIG.  2 . The leading element  79 , as well as a trailing element  82  of the signature  78  is pushed into the pre-fold clamping gap  81  by the amount of the penetration depth of the folding blade  23 . FIG. 2 shows a position D of the cylinders  22 ,  27 , in which the pre-fold clamping elements  31 ,  32 , as well as the folding blade  23  have already passed through the central line  56  by an angle of rotation α. Following the retraction of the folding blade  23 , as depicted in FIG. 2, the pre-fold clamping elements  31 ,  32  close pincer-like, or respectively jaw-like, and form a pre-fold  83  on the signature  78 . 
     In the process, while the signature  78  is inserted into the pre-fold clamping gap  81 , the point spurs of the point spur system  26  are pulled out of the leading element  79  of the signature  78  against the clockwise turning direction B of the transport and folding jaw cylinder  22  in a manner as disclosed in DE 195 33 064 A1 which corresponds to U.S. Pat. No. 5,860,342. 
     Because the enlargements or lobes  46 ,  47  of the supports  43 ,  44  are formed in a cylinder shape, the pre-fold  83  is formed as a bead or bulge on the other side of an imagined contact line of the two enlargements or lobes  46 ,  47  and radially inside the two pre-fold clamping elements  31 ,  32 . For this reason, the pre-folded product  83 ,  79 ,  82  shaped in this way cannot slip out of the closed pre-fold clamping elements  31 ,  32  during the further transport on the pre-fold cylinder  27 . Thus, the radius r of an enlargement or lobe  46 ,  47  is less than the penetration depth of a folding blade  23  into a pre-fold clamping gap  81 . Following approximately a quarter revolution of the pre-fold cylinder  27 , starting at the position  56  of the pre-fold depicted in FIG. 2 in the counterclockwise direction of rotation C, the pre-folded product, not represented, is received between the two belt systems  63 ,  64 . After a more than half a revolution of the pre-fold cylinder  27  following the pre-folding process, the belt systems  63 ,  64  separate from the pre-fold cylinder  27  and represented in FIG. 1, wherein the first belt system  63  has just lifted the pre-folded product by its pre-fold  83 , while the pre-fold clamping elements  31 ,  32  are opened, and thereafter both belt systems  63 ,  64  conduct the pre-folded product to the folding rollers  61 ,  62  for finish-folding. 
     After leaving the folding rollers  61 ,  62 , the finish-folded printed product is transferred to the paddle wheel  69  and is thereafter deposited on the delivery belt  72 . 
     Supplementing the already mentioned advantages, the advantages of pre-folding during two-stage transverse folding consist in that, because of the rounding of the portions of the pre-folding clamping elements near the periphery, there is a greater supported distance for the signature between the folding blade and the pre-fold clamping element than with known folding jaw systems. Because of this greater supported distance and the rounding of the portions near the periphery, it is possible to insert thick folded products without damage and with reduced force into the pre-fold clamping gap. Because of their large contact surfaces, the rounded pre-fold clamping elements treat the outer layers of the folded products gently. The inner layers of the folded product are treated gently in that the folding blade can roll off over the rounded pre-fold clamping elements without jamming the pre-folded product in the process. 
     In order to prevent the point spurs from tearing during the folding process, during their return, the point spurs are additionally moved back in respect to the front edge of the leading element of the signature by approximately the amount of the penetration depth of the folding blade into the pre-fold clamping gap. 
     While preferred embodiments of a method and device for cross-folding signatures in accordance with the present invention have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that a number of changes in, for example, the type of rotary printing press used, the drive assembly for the cylinders and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the following claims.