Abstract:
A method of folding a printed product is provided. The method includes the steps of cutting a web so as to form a signature having lead edge tabs, the signature having perforation slots and folding the signature so the lead edge tabs enter the perforation slots. Lead edges may be more easily prevented from dislodging and dog-earing and skewing may be minimized.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 12/077,996, filed Mar. 24, 2008, the entire disclosure of which is hereby incorporated by reference herein. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    The present invention relates generally to a printing press and specifically to a printed product cutting and folding apparatus and method. 
         [0003]    U.S. Pat. No. 5,386,979 discloses a rotary folding apparatus with a special cylinder arrangement for web-fed rotary printing presses. After a desired mode of operation, first and second cross-fold or delta-fold, has been pre-set and respective folding jaws have been positioned, the formation of the first cross-fold occurs by pushing or tucking copies or signatures into the folding jaws with the aid of tucker blades on a tucker blade cylinder, the folding jaws being in either a first or second position, depending upon the mode of operation. The copies or signatures formed with a first cross-fold are removed from the circumference of the folding jaw cylinder by a gripper bar of a gripper cylinder. Tucker blades of the gripper cylinder push or tuck the copies or signatures into the suitably positioned folding jaws of the folding jaw cylinder so as to form the second cross-fold or the delta-fold. 
         [0004]    U.S. Patent Pub. 2003/0096688 discloses a variable circumference folder. From a gathering cylinder, products are transferred from pin systems into folding jaws of a folding-jaw cylinder by a folding blades under control to produce a first crossfold. The products may then be subjected to further folds using known techniques. For example, a double parallel or delta-fold is produced by the products being transferred to gripper systems of a second crossfold cylinder and pushed into folding jaws of the folding jaw cylinder by folding blades. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    An apparatus for cutting and folding printed products is provided. The apparatus includes a perforator, a first cutting device creating first slits in the web, a second cutting device creating second slits in the web longitudinally offset from the first slits so as to form a signature with a staggered edge, and a folder delta-folding the signature so that the staggered edge engages slots in the signature, the slots created by the perforator. 
         [0006]    A method of folding a printed product is also provided. The steps include cutting a web so as to form a signature having lead edge tabs, the signature having perforation slots; and folding the signature so that the lead edge tabs enter the perforation slots. 
         [0007]    A signature is also provided. The signature includes a lead edge including tabs, a tail edge opposite the lead edge, perforation slots between the lead edge and the tail edge, a first fold line between the lead edge and the perforation slots and a second fold line along the perforation slots. The signature is folded along the first fold line and the second fold line, the perforation slots receiving and engaging the tabs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention is described below by reference to the following drawings, in which: 
           [0009]      FIG. 1  shows a schematic side view of a folding apparatus according to an embodiment of the present invention; 
           [0010]      FIG. 2  shows a schematic top view of an unfolded signature formed into a delta product by the folding apparatus shown in  FIG. 1 , with a perforation blade, a first cutting blade and a second cutting blade schematically arranged to illustrate where the perforation blade, the first cutting blade and the second cutting blade have acted to form the signature; 
           [0011]      FIG. 3  shows a perspective view of the signature shown in  FIG. 2  as an open delta product; 
           [0012]      FIG. 4  shows a enlarged schematic perspective view of the signature shown in  FIG. 2  engaged by a first jaw shown in  FIG. 1 ; 
           [0013]      FIG. 5  shows a schematic enlarged side view of the signature shown in  FIG. 2  being delta-folded by a second tucking blade and a second jaw shown in  FIG. 1 ; 
           [0014]      FIG. 6  shows a perspective view of the signature shown in  FIG. 2  before lead edge tabs enter into perforation slots during delta-folding; 
           [0015]      FIG. 7  shows a schematic side view of the signature shown in  FIG. 2  being delta-folded with lead edge tabs engaged by perforation slots and the signature is engaged by the second jaw shown in  FIG. 1 ; and 
           [0016]      FIG. 8  shows a schematic side view of the signature shown in  FIG. 2  folded as a final delta product. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  shows a schematic side view of a web  22  entering a folding apparatus  20  according to an embodiment of the present invention. Web  22  as defined herein can include a plurality of ribbons. Nip rollers  24 ,  25 ,  26 ,  27  transport web  22  into folding apparatus  20  and can help maintain proper orientation of web  22 . Perforating cylinders  30 ,  31  cross perforate web  22  with a cross perforating blade  130 . Web  22  may pass through a creaser  28  after web  22  is cross perforated. First cutting cylinders  32 ,  33  cut web  22 , while web  22  passes between cylinders  32 ,  33 , with a first cutting blade  132 . First cutting blade  132  may create slits  142  ( FIG. 2 ) in web  22  in a manner that partially defines a tail edge  124  ( FIG. 2 ) of a signature  122  ( FIG. 2 ), while partially defining tabs  334  ( FIG. 2 ) on a lead edge  323  ( FIG. 2 ) of a second signature that may be formed after signature  122 . Second cutting cylinders  34 ,  35  may cut web  22 , while web  22  passes between cylinders  34 ,  35 , with a second cutting blade  134 . Second cutting blade  134  may create slits  144  ( FIG. 2 ) in web  22  in a manner that finishes defining tail edge  124  ( FIG. 2 ) of signature  122  ( FIG. 2 ), while finishing defining tabs  334  ( FIG. 2 ) on a lead edge  323  ( FIG. 2 ) of a second signature that may be formed after signature  122 . 
         [0018]    After web  22  has been perforated by perforating cylinders  30 ,  31  and cut by first and second cutting cylinders  32 ,  33 ,  34 ,  35 , successive signatures  122  ( FIG. 2 ) are formed. Successive signatures  122  ( FIG. 2 ) may be one or more sheets thick. In an alternative embodiment perforating cylinders  30 ,  31  may perforate signatures  122  ( FIG. 2 ) after web  22  has been cut into signatures  122  ( FIG. 2 ) by cutting cylinders  32 ,  33 ,  34 ,  35 . Accelerating tapes  38  may help guide the signatures  122  ( FIG. 2 ) as signatures  122  pass from cutting cylinders  34 ,  35  to a collection cylinder  40 . Signatures  122  ( FIG. 2 ) are gripped by first grippers  41  on collection cylinder  40 .  FIG. 1  shows first gripper  41  on collection cylinder  40  gripping a signature  122   a.  Signature  122   a  gripped by gripper  41  is passing through a nip  45  formed by collection cylinder  40  and a jaw cylinder  50 . A first tucking blade  42  begins to force a portion of signature  122   a  into a first jaw  53  of jaw cylinder  50 . As first tucking blade  42  forces a portion of signature  122   a  in first jaw  53 , first jaw  53  may engage signature  122   a,  forming a first cross-fold on signature  122   a.  Gripper  41  then releases signature  122   a  and first jaw  53  transports signature  122   a,  via rotation of jaw cylinder  50  about an axis of jaw cylinder  50 , to be gripped by a second gripper  61  on a delta cylinder  60 . 
         [0019]    A signature  122   b,  which has already been first cross-folded by first tucking blade  42  and first jaw  53 , is gripped by a second gripper  61  on delta cylinder  60  as signature  122   b  passes through a nip  55  formed by jaw cylinder  50  and delta cylinder  60 . A second tucking blade  62  on delta cylinder  60  may be beginning to force a portion of signature  122   b  into a second jaw  54  of jaw cylinder  50 . As second tucking blade  62  forces a portion of signature  122   b  into second jaw  54 , second jaw  54  may engage signature  122   b,  forming a second cross-fold, or delta-fold, on signature  122   b.  After signature  122   b  is delta-folded by second tucking blade  62  and second jaw  54 , while still engaged by second jaw  54 , signature  122   b  passes through a nip formed between a finishing roller  70  and jaw cylinder  50  to complete the delta-fold of signature  122   b.  A signature  122   c,  adjacent to a surface of jaw cylinder  50 , has been first cross-folded by first tucking blade  42  and first jaw  53  and delta-folded by second tucking blade  62  and second jaw  54  to form a final delta product  222  ( FIG. 8 ). 
         [0020]      FIG. 2  shows a schematic top view of a signature  122  cut from web  22  by cutting blades  132 ,  134 , and perforated by perforating blade  130 , according to the embodiment of the invention show in  FIG. 1 . Perforation blade  130 , first cutting blade  132  and second cutting blade  134  are schematically arranged to illustrate where perforation blade  130 , first cutting blade  132  and second cutting blade  134  act on web  22 . Second cutting blade  134  may be located downstream, in relation to a direction  150  of web  22  travel, of first cutting blade  132  and perforation blade  130 , with first cutting blade  132  located downstream of perforation blade  130 . In alternative embodiments, blades  130 ,  132 ,  134  can be arranged differently in relation to direction  150 . 
         [0021]    Signature  122  includes a lead edge  123  and a tail edge  124 . Each cutting blade  132 ,  134  is segmented and has spaced teeth  260 ,  268 , respectively, that pierce web  22  during cutting. Thus, cutting blades  132 ,  134  cut slits  142 ,  144 , respectively, in web  22 . Slits  144  made in web  22  by teeth  268  are aligned in between slits  142  made in web  22  by teeth  260 , in a manner that separates web  22  into successive signatures  122 . Slits  142 ,  144  define leading edge  123  of signature  122 , while severing a preceding signature from web  22  and defining a tail edge of the preceding signature. Cutting blades  132 ,  134  cut web  22  so that slits  142  are longitudinally offset from, or staggered behind, slits  144 , in relation to direction  150  that web  22  travels. This offset cutting creates tabs  234  at leading edge  123 , which has a staggered arrangement. Slits  142 ,  144  cut by cutting blades  132 ,  134 , respectively, also define tail edge  124  of signature  122 . Tail edge  124  may have a staggered arrangement similar to lead edge  123 . When slit  144  is cut in web  22 , tail edge  124  of signature  122  is formed and signature  122  is created from web  22 . Boundaries  240 , connecting slits  142 ,  144 , are also defined in forming lead edge  123  and tail edge  124  of signature  122 , by severing web  22 . Boundaries  240  may be created by tearing of web  22  caused by tension exerted on web  22 , after web  22  is cut by cutting blades  132 ,  134 . Alternatively, one or both of blades  132 ,  134  may have teeth  260 ,  268 , respectively, shaped to define boundaries  240 , or one or more separate longitudinally extending blades may be provided. 
         [0022]    Signature  122  is of a length L and includes perforation slots  230  created by perforation blade  130 . Perforation slots  230  are located parallel to lead edge  123  and tail edge  124  at a distance approximately equal to one-third of length L of signature  22  (L/3) from tail edge  124  and a distance approximately equal to two-thirds of length L of signature  22  (2L/3) from lead edge  123 . Perforation slots  230  of signature  122  are sized to engage tabs  234  of signature  122  as signature  122  is delta-folded along a second fold line  330 , which may be substantially defined by perforation slots  230 . A first fold line  329  is shown to illustrate where signature  122  is first cross-folded before signature  122  is delta-folded. First fold line  329  runs parallel to second fold line  330  and lead edge  123 . First fold line may be located a distance equal to one-third the length L of signature  122  (L/3) from lead edge  123 , a distance equal to two-thirds the length L of signature  122  from tail edge  124  (2L/3) and distance equal to one-third the length L of signature  122  (L/3) from second fold line  330  and perforated slots  230 . 
         [0023]    Slits  142 ,  144  and boundaries  240  defining tail edge  124  of signature  122  also define what may be leading edge  323  of a second signature to be created after signature  122 . Accordingly, perforation slots  230  and slits  142  have been created between blades  132 ,  134  in web  22  by perforation blade  130  and cutting blade  132 , respectively. Blade  134  may cut web  22  as web  22  travels in direction  150 , and boundaries  240  may be created to define a tail edge of the second signature. Between blades  130 ,  132 , perforation slots  230  have been created in web  22 , which may be included in a third signature following the second signature. 
         [0024]    In an alternative embodiment, cutting blades  132 ,  134  may be replaced by a single cutting blade which is shaped to cut web  22  to create signatures  122  with lead edge  123  having a staggered arrangement and including tabs  234 . Tail edge  124  may also be created by this single cutting blade with a staggered arrangement or can be created with or without a staggered arrangement by another blade. 
         [0025]      FIG. 3  shows a perspective view of signature  122  shown in  FIG. 2  as an open delta product. Signature  122  has been folded along first and second fold lines  329 ,  330 . Perforation slots  230  are sized to receive lead edge tabs  234 . 
         [0026]      FIG. 4  shows an enlarged schematic perspective view of signature  122  shown in  FIG. 2  engaged by first jaw  53  shown in  FIG. 1 . Signature  122  is being first cross-folded at first fold line  329  at nip  45  and is being rotated about an axis of jaw cylinder  50  by first jaw  53 , via rotation of jaw cylinder  50 . Lead edge  123  of signature  122  has already passed between nip  45 . Signature  122  includes perforation slots  230  along second fold line  330 , which, along with tail edge  124  of signature  122  is located adjacent a surface of collection cylinder  40 , which is being rotated about an axis of collection cylinder  40 . 
         [0027]      FIG. 5  shows a schematic enlarged side view of signature  122  shown in  FIG. 2  being delta-folded by second tucking blade  62  and second jaw  54  shown in  FIG. 1 . Signature  122  has been first cross-folded at first fold line  329  by first jaw  53  and is beginning to be delta-folded, or second cross-folded, at second fold line  330  as signature  122  passes through nip  55 . Prior to the operations shown in  FIG. 5 , first jaw  53  released signature  122  and signature  122  was gripped by second gripper  61 . In  FIG. 5 , gripper  61  has just released signature  122 . Second tucking blade  62  is tucking lead edge  123  so that lead edge tabs  234  ( FIG. 2 ) enter, and are removably engaged by, perforation slots  230  ( FIG. 2 ) in a manner latching lead edge tabs  234  into place inside perforation slots  230  while signature  122  is delta-folded. As an advantageous result, lead edge  123  does not dislodge from second jaw  54  as signature  122  is engaged by second jaw  54  at second fold line  330 . Latching of lead edge tabs  234  ( FIG. 2 ) with perforation slots  230  ( FIG. 2 ) advantageously may prevent dog-ear folds from forming at lead edge  123  of signature  122  and may also minimize skewing of signature  122 . After second tucking blade has caused lead edge tabs  234  ( FIG. 2 ) to enter perforation slots  230  ( FIG. 2 ), second tucking blade  62  may retract away from second jaw  54  while second jaw  54  securely engages signature  122 . 
         [0028]      FIG. 6  shows a perspective view of signature  122  shown in  FIG. 2  before lead edge tabs  234  enter into perforation slots  230  during delta-folding. Lead edge tabs  234  may be sized slightly smaller than perforation slots  230  so that lead edge tabs  234  can enter perforation slots  230  during delta-folding and so that lead edge tabs  234  do not slip out of perforation slots  230  as delta-folding at second fold line  330  is completed. Signature  122  has already been cross-folded along first fold line  329  so that lead edge  123  is adjacent to second fold line  330 . When delta-folding is complete, tail edge  124  may be adjacent to first fold line  329 . 
         [0029]      FIG. 7  shows a schematic side view of signature  122  shown in  FIG. 2  being delta-folded with lead edge tabs engaged by perforation slots  230  and signature  122  is engaged by second jaw  54 . Second jaw  54  may be clamping signature  122  so that signature  122  does not become misaligned as delta-folding of signature  122  is completed. Lead edge tabs  234  have entered into perforation slots  230  ( FIG. 2 ) and are shown passing through perforation slots  230  at second fold line  330 . As delta-folding of signature  122  is completed first fold line  329  travels towards tail edge  124 . 
         [0030]      FIG. 8  shows a schematic side view of signature  122  shown in  FIG. 2  folded as a final delta product  222 . Signature  122 , folded as a substantially flat delta product, is folded into three sections. A first section is defined between tail edge  124  and second fold line  330 , at which signature  122  is folded. A second section is defined between second fold line  330  and first fold line  329 , at which signature  122  is folded. A third section is defined between first fold line  329  and lead edge  123 . The third section is between the first and second sections. Lead edge tabs  234  ( FIG. 2 ) are passing through perforation slots  230  ( FIG. 2 ). 
         [0031]    The present invention may prevent inner sheets of delta products from being pulled out of second jaws  54  ( FIG. 1 ) by second tucking blades  62  ( FIG. 1 ) as second tucking blade  62  retracts while signature  122  is delta-folded. Even if only a small corner of lead edge  123  ( FIG. 2 ) is dislodged from second jaws  54  ( FIG. 1 ) a dog-ear fold can be created on inner sheets of signature  122 . Prior attempts to prevent dog-earring during delta-folding include using a two millimeter lap on an open end of inner sheets, which gives signatures more bulk as signatures are gripped by second jaws, making it difficult to pull out the inner sheets. Dog-earring can be further prevented by flatter geometry of a second fold off guide, which may put less bending force on the inner sheets so the laps do not pop out of the second jaws. Also, second jaws may include second jaw blades that pierce signatures to maintain a hold on inner sheets as signatures are gripped by second jaws. 
         [0032]    In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.