Abstract:
A folder includes a cylinder having a first gripping device receiving a folded edge of a signature and rotating the signature at a first surface speed. A conveyor presses the signature against the outer surface and the conveyor contacts the signatures at a second surface speed slower than the first surface speed. The present invention also provides a method for removing signatures from a cylinder.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of U.S. patent Ser. No. 11/368,980, filed Mar. 6, 2006, the entire text of which is hereby incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    The present invention relates generally to printing presses and more particularly to a folder of a printing press. 
         [0003]    Several processes have been used previously to remove signatures from a half fold jaw. U.S. Pat. No. 5,102,111, hereby incorporated by reference herein, discloses a folder or folding machine apparatus for a printing machine. A first conveyor conveys signatures at a given speed at a same speed as the printing press, the signatures are then stripped by strippers. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a folder comprising: 
         [0005]    a cylinder having a first gripping device receiving a folded edge of a signature and rotating the signature at a first surface speed, and 
         [0006]    a conveyor pressing the signature against the outer surface, the conveyor contacting the signature at a second surface speed lower than the first surface speed. 
         [0007]    By having a second surface speed lower than the first, the conveyor can aid in removing the signature from the cylinder 
         [0008]    The present invention also provides a method for removing signatures from a cylinder comprising the steps of: 
         [0009]    transporting the signatures around a cylinder at a first surface speed, the signatures being gripped at a folded edge by a gripping device; 
         [0010]    pressing the signatures at a first location with a first conveyor against the cylinder, the first conveyor at the first location moving at a second surface speed lower than the first surface speed; 
         [0011]    releasing the signatures from the gripping device; and 
         [0012]    further transporting the signatures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Preferred embodiments of the present invention will be elucidated with reference to the drawings, in which: 
           [0014]      FIG. 1  shows a folder according to the present invention; 
           [0015]      FIG. 2  shows an enlarged view of a gripping device; 
           [0016]      FIG. 3  shows a second embodiment of the folder according to the present invention; and 
           [0017]      FIG. 4  shows an outer surface of the folder of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]      FIG. 1  shows a preferred exemplary embodiment of a folder  10 . Folder  10  includes a jaw cylinder  30 , a first conveyor  20 , a second conveyor  60  and a stationary support such as stripper  90 . Jaw cylinder  30  includes a gripping device  40 . Gripping device  40  includes a stationary part  42 , a movable jaw  44  and a jaw gap  46 . Jaw cylinder  30  may include a plurality of gripping devices  40  spaced axially and circumferentially. Jaw cylinder  30  moves at a velocity V 1 , rotationally driven about a central axis  32 , shown in  FIG. 1 . in the clockwise direction. Jaw cylinder  30  has an outer surface  34  with circumferentially extending grooves between the axially spaced gripping devices  40  and a plurality of axially spaced strippers  90  may at least be partially located in these grooves. 
         [0019]    First conveyor  20  includes a belt  22  and a plurality of rollers  24 ,  25 . Belt  22  moves around roller  24  and roller  25  at a velocity V 2  in the direction indicated in  FIG. 1 . Second conveyor  60  includes a belt  62  and a roller  64 . Belt  62  moves around roller  64  at velocity V 2  in the direction D indicated in  FIG. 1 . V 2  is less then V 1  at least when belt  22  presses signature  50  against outer surface  34 . 
         [0020]    Tucking blade  70  from a transfer cylinder  72 , for example, the transfer cylinder disclosed in U.S. Pat. No. 6,923,753, hereby incorporated by reference herein, tucks a signature  50  into jaw gap  46 . Movable jaw  44  pushes against signature  50  to place folded edge  51  in jaw gap  46  in between movable jaw  44  and stationary part  42  ( FIG. 2 ). 
         [0021]    Gripping device  40  holds signature  50  as signature  50  travels around jaw cylinder  30  at velocity V 1 . When jaw cylinder  30  reaches a point A in the jaw cylinder rotation, cam/cam follower interaction may, for example, cause movable jaw  44  to release signature  50 . 
         [0022]    At a point beyond point A, belt  22  presses signature  50  against jaw cylinder  30 . Belt  22  moving at slower velocity V 2  guides signature  50  along a segment of jaw cylinder  30  between point A and a point B. Thus, due to the difference between V 2  and V 1 , folded edge  51  slides out of gripping device  40 . 
         [0023]    After point B, belt  22  continues to carry signature  50  away from jaw cylinder  30  at velocity V 2 . Stationary stripper  90  rests partially in circumferentially extending grooves of jaw cylinder  30  and is positioned to intercept signature  50 , as signature  50  travels along outer surface  34 . Signature  50  slides along stationary stripper  90  to a gap  66  located between belt  22  and belt  62 . Belt  22  and belt  62  move at velocity V 2  and transport signature  50  along for further processing. 
         [0024]      FIG. 2  shows an enlarged view of gripping device  40 . Gripping device  40  includes stationary part  42 , jaw gap  46  and movable jaw  44 . Signature  50  includes folded edge  51 , a lower surface  52  and an upper surface  53 . 
         [0025]    As shown in  FIG. 2 , due to slower velocity V 2  on upper surface  53  of signature  50 , a force F develops on signature  50  which pulls folded edge  51  out of jaw gap  46  after movable jaw  44  releases at point A. Accordingly, strippers  90  ( FIG. 1 ) can be used at a reduced capacity. 
         [0026]    As force F pulls on signature  50 , upper surface  53  may slide in the same direction as F. The fold position of folded edge  51  or lap of the signature thus may be altered by slower speed V 2 . The speed V 2  can be set as a function of the fold position set by tucking blade  70 , so the fold position as signature  50  exits jaw cylinder  30  is as desired, for example, exactly half of a signature. Outer surface  34  is preferably cylindrical with a relatively high finish or friction reducing substance so signature  50  slides on outer surface  34  when force F is applied to upper surface  53 . Stripper  90  also preferably has a high finish or friction reducing substance on its contact surface. Also, it should noted that stripper  90  may have a curved or cylindrical top surface to aid signature slip. 
         [0027]      FIG. 3  shows a second embodiment with a movable support  190  instead of stationary support  90 . Movable support  190  includes tapes  192  and a plurality of rollers  194 ,  196 ,  198 . Tapes  192  move around roller  198 , roller  196 , roller  194  and around jaw cylinder  30 . Tapes  192  travel along outer surface  34  recessed in a plurality of grooves  36  (see  FIG. 4 ) as to not interfere with gripping device  40  or tucking blade  70 . At or soon thereafter point B, tapes  192  exit jaw cylinder  30  and contact a signature  50  as tapes  192  surface on outer surface  34 . 
         [0028]    Signature  50  leaves jaw cylinder  30  transported between tapes  192  and belt  22 . Second conveyor  60  is positioned to receive signature  50  from tapes  192  and belt  22 . Thus, signature  50  enters a gap  66  located between belt  22  and belt  62 . Belt  22  and belt  62  move at velocity V 2  and transport signature  50  along for further processing. Conveyor  20 , conveyor  60  and roller  198  can also be located at a different angle with respect to jaw cylinder  30  so gravity effects can be further minimized. 
         [0029]      FIG. 4  shows tapes  192  in circumferentially extending grooves  36 . Grooves  36  are recessed in outer surface  34 . Tapes  192  are spaced around gripping device  40  as to not interfere with gripping device  40 . Tapes  192  move in grooves  36  around outer surface  34 . Tapes  192  may move for example at speed V 1  or V 2  so as to slip with respect to cylinder  30  in grooves  36 . 
         [0030]    The speed V 2  with respect to V 1  may be determined as a function of various variables, such as paper type, surface friction present, belt material, types of strippers used, if any. The speed V 2  may be for example 75 to 95% of V 1 , for example 86%. However, other speed percentages may be possible within the scope of the present invention. 
         [0031]    Gripping device as defined herein can be any device for receiving a fold of a signature. 
         [0032]    Tapes  192  may be rounded belting or other conveyor material.