Abstract:
A variable cutoff cylinder alignment apparatus is provided. The variable cutoff cylinder alignment apparatus includes a plate cylinder support box for supporting an exchangeable variable cutoff plate cylinder, a blanket cylinder support box for supporting an exchangeable variable cutoff blanket cylinder and an alignment stop adapted to align the blanket cylinder support box and the plate cylinder support box. The plate cylinder support box supports an exchangeable plate cam and the blanket cylinder support box includes a blanket cam. The exchangeable plate cam is capable of contacting the stop and the exchangeable blanket cam is capable of contacting the plate support box to align the blanket cylinder support box and the plate cylinder support box. The plate cylinder support box and the blanket cylinder support box are capable of aligning cylinders of different sized cutoffs. A variable cutoff offset printing press and a method of aligning printing cylinders during a cutoff change are also provided.

Description:
Priority is claimed to U.S. Provisional Application No. 61/199,886 filed Nov. 21, 2008, and hereby incorporated by reference herein. 
    
    
     The present invention relates generally to printing presses and more particularly to a variable cutoff alignment apparatus for a printing press and a method of aligning printing cylinders during a cutoff change. 
     BACKGROUND 
     In order to vary a cutoff length of signatures printed by a printing press, plate cylinders, blanket cylinders and impression cylinders may have to be removed from the printing press and replaced with respective cylinders having circumferences that correspond to a new desired cutoff length. Alternatively, each cylinder may include a sleeve that may be removed and replaced with a sleeve having a circumference that corresponds to the new desired cutoff length. Changing cylinders or sleeves may require the mechanisms supporting the cylinders to be separated from one another. After the change, the new cylinders may need to be brought back into contact with one another at a desired position. 
     SUMMARY OF THE INVENTION 
     A variable cutoff cylinder alignment apparatus is provided. The variable cutoff cylinder alignment apparatus includes a plate cylinder support box for supporting an exchangeable variable cutoff plate cylinder, the plate cylinder support box including an exchangeable plate cam, a blanket cylinder support box for supporting an exchangeable variable cutoff blanket cylinder, the blanket cylinder support box including an exchangeable blanket cam and an alignment stop for aligning the variable cutoff blanket cylinder and the variable cutoff plate cylinder. The exchangeable plate cam capable of contacting the stop and the exchangeable blanket cam capable of contacting the plate support box to align the variable cutoff blanket cylinder and the variable cutoff plate cylinder for different sized cutoffs. 
     A method of aligning printing cylinders during a cutoff change is also provided. The method includes the steps of removing a first plate cylinder and a first plate cam from a plate cylinder support box and removing a first blanket cylinder and a first blanket cam from a blanket cylinder support box; mounting a second plate cylinder and a second plate cam on the plate cylinder support box and mounting a second blanket cylinder and a second blanket cam on the blanket cylinder support box; and aligning the second plate cylinder and the second blanket cylinder by contacting an aligning stop with the second plate cam and contacting the plate cylinder support box with the second blanket cam. 
     A variable cutoff offset printing press is also provided. The variable cutoff offset printing press includes an exchangeable variable cutoff plate cylinder, an exchangeable variable cutoff blanket cylinder, a plate cylinder support box supporting the exchangeable variable cutoff plate cylinder, a blanket cylinder support box supporting the exchangeable variable cutoff blanket cylinder and an alignment stop adapted to align the exchangeable variable cutoff plate cylinder and the exchangeable variable cutoff blanket cylinder. The plate cylinder support box includes an exchangeable plate cam and the blanket cylinder support box includes an exchangeable blanket cam. The exchangeable plate cam is capable of contacting the stop and the exchangeable blanket cam is capable of contacting the plate support box to align the exchangeable variable cutoff blanket cylinder and the exchangeable variable cutoff plate cylinder. The plate cylinder support box and the blanket cylinder support box are capable of aligning cylinders of different sized cutoffs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention will be elucidated with reference to the drawings, in which: 
         FIG. 1  shows a schematic side view of a printing unit of a printing press arranged in a printing arrangement by a cylinder alignment apparatus according to an embodiment of the present invention; 
         FIG. 2  shows the printing unit shown in  FIG. 1  with cylinders of the printing unit in a maximum separation arrangement; 
         FIG. 3  shows the printing unit shown in  FIGS. 1 and 2  including larger plate and blanket cylinders in an aligning arrangement; 
         FIG. 4  shows the printing unit shown in  FIGS. 3  with the plate cylinder and an impression cylinder in a throw off arrangement; and 
         FIG. 5  shows the printing unit shown in  FIG. 4  with the plate cylinder in a plating arrangement. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a schematic side view of a printing unit  10  of a printing press including a cylinder alignment apparatus  20  according to an embodiment of the present invention. The printing press may include multiple printing units. The printing press may include non-perfecting printing units. Each printing unit may print with a different color ink as desired. The printing press may also include a dryer, a folder having a former for folding a web, cutting cylinders and folding cylinders. 
     Printing unit  10  includes an impression cylinder  12 , a blanket cylinder  14 , a plate cylinder  16  and an inking and dampening apparatus  18 . In operation, inking and dampening apparatus  18  provides ink and dampening solution to plate cylinder  16 . Plate cylinder  16 , which may be provided with an imaged printing plate mounted thereon, transfers inked images to a printing blanket on blanket cylinder  14  at a nip  15 . A printing blanket on blanket cylinder  14  then transfers the images to a web passing between blanket cylinder  14  and impression cylinder  12  at a nip  13 . 
     Cylinder alignment apparatus  20  includes an impression cylinder support box  22  supporting impression cylinder  12 , a blanket cylinder support box  24  supporting blanket cylinder  14  and a plate cylinder support box  26  supporting plate cylinder  16 . Support boxes  22 ,  24 ,  26  are coupled to a supporting frame at respective pivot points  23 ,  25 ,  27  on a first side. One a second side, impression cylinder support box  22  is coupled to an actuator  33  and plate cylinder support box  26  is coupled to an actuator  37 . Actuators  33 ,  37  may be pneumatic air cylinders or hydraulic cylinders. An impression cam  42  is coupled to support box  22 , first and second blanket cams  43 ,  44  are coupled to support box  24  and first and second plate cams  45 ,  46  are coupled to support box  26 . An alignment stop  40 , which may be coupled to the supporting frame, is near inking and dampening apparatus  18 . Alignment stop  40  may be eccentrically mounted on the supporting frame and may be movable between a non-aligning position and an aligning position. In  FIG. 1 , alignment stop is in the non-aligning position. In the aligning position, alignment stop  40  provides a reference point to assist in aligning support boxes  22 ,  24 ,  26  with one another, and thus assists in aligning cylinders  12 ,  14 ,  16  with one another. When cylinders  12 ,  14 ,  16  are arranged in a printing arrangement, as shown in  FIG. 1  for example, impression cam  42  contacts first blanket cam  43 , second blanket cam  44  contacts first plate cam  45  and plate cylinder  16  contacts one or more rollers of inking and dampening apparatus  18 . Alignment stop  40  is pulled away from second plate cam  46  during printing in the non-aligning position. Support box  22  may be coupled to support box  24  via a latch  29 . 
     Support box  24  may be locked into a set position for a given cutoff, which may be accomplished by be locking support box  24  to the supporting frame via lock mechanism  50 . When support box  24  is in the locked position, support box  24  provides a reference point for support boxes  22 ,  26 . Thus, once blanket support box  24  is locked into a desired position for a given printing cutoff, impression cylinder and plate cylinder and their respective support boxes may be thrown on and off as necessary during the printing process, while the blanket cylinder support box remains stationary. 
       FIG. 2  shows printing unit  10  shown in  FIG. 1  with cylinders  12 ,  14 ,  16  in a maximum separation arrangement which allows cylinders  12 ,  14 ,  16  to be removed for a cutoff change. Sleeves and cams can be changed. Support box  24  is unlocked from the supporting frame via locking mechanism  50  and latch  29  is unlatched from support box  24 . Support boxes  22 ,  24 ,  26  rest on respective support stops  34 ,  35 ,  36 . Actuator  37  has moved support box  26  away from alignment stop  40  and inking and dampening apparatus  18 . Actuator  33  has moved support box  22  away from support box  24  so that first blanket cam and impression cam  42  are no longer in contact. Support box  24  has moved away from support box  26  so blanket cam  44  and plate cam  45  are no longer in contact. Cylinders  12 ,  14 ,  16  (or sleeves of cylinders  12 ,  14 ,  16 ) may then be removed from respective supporting boxes  22 ,  24 ,  26 , first and second cams  43 ,  44  may be removed from support box  24  and second cam  46  may be removed from support box  26 . Alignment stop  40  is in the non-aligning arrangement. 
       FIG. 3  shows printing unit  10  shown in  FIGS. 1 and 2  including plate cylinder  116 , blanket cylinder  114  and impression cylinder  12 . Cylinders  114 ,  116 ,  12  are shown in an aligning arrangement and alignment stop  40  is in the aligning position. Cylinders  114 ,  116  have greater circumferences than cylinders  14 ,  16  and thus cylinders  114 ,  116  print images of a larger cutoff than cylinders  14 ,  16 . Blanket cams  43 ,  44  have been replaced with blanket cams  143 ,  144  and plate cam  46  has been replaced with a plate cam  146 . Cams  143 ,  144 ,  146  are radially larger than cams  43 ,  44 ,  46 . To properly align cylinders  12 ,  114 ,  116 , cam  146  is brought into contact with alignment stop  40 , which is now in a gauging/alignment position for alignment of the cylinders, cam  144  is brought into contact with cam  45 , and cam  42  is brought into contact with cam  143 . Support box  24  may then be locked into position on the supporting frame via locking mechanism  50  and support boxes  22 ,  26  may be pushed against support box  24  by contacting cams  143 ,  144  with cams  42 ,  45 , respectively, to gauge the amount of pressure between cylinders  116 ,  114  at a nip  115  and the amount of pressure between cylinders  114 ,  12  at a nip  113 . Support box  24  may be locked in place until another cutoff change is required and cylinders  114 ,  116  (or sleeves on cylinders  114 ,  116 ) are replaced. 
     In situations where some type of maintenance is required, but no change in cutoff is necessary, support box  24  may not need to be moved. If a plate on plate cylinder  116  needs to be replaced, a blanket on blanket cylinder  114  needs to be replaced or impression cylinder  12  needs to be replaced, or any cylinder  12 ,  114 ,  116  needs to be repaired, but no cutoff change is required, support box  24  may be left in the locked position. In such an instance, alignment stop  40  may be moved out of the gauging/alignment position and one or more rollers of inking and dampening apparatus  18  may be moved away from plate cylinder  116 . Actuator  37  may then move support box  26  away from support box  24  and actuator  33  may move support box  22  away from support box  24 . After cylinders  12 ,  114 ,  116  are thrown off from one another, the particular maintenance may be performed and it may be unnecessary to gauge the pressure between cylinders  12 ,  114 ,  116 . 
     Also, if the web is replaced with web of a different thickness, support box  24  may remain in the locked position and actuator  33  may adjust the position of support box  22  accordingly so that cylinders  12 ,  114  are correctly positioned with respect to one another. 
     Blanket cam  144  is sized such that a radius R bc2  of blanket cam  144  with respect to a center axis of blanket cylinder  114  is equal to the radius R b  of blanket cylinder  114  plus the difference between the radius R p  of plate cylinder  116  and a radius R pc1  of plate cam  45  with respect to a center axis of plate cylinder  116  (R bc2 =R b +(R p −R pc1 )). 
       FIG. 4  shows printing unit  10  shown in  FIGS. 3  with plate cylinder  116  and impression cylinder in a throw off arrangement. Both impression cylinder  12  and plate cylinder  116  are thrown off of blanket cylinder  114 . Alignment stop  40  is in the non-aligning position. Blanket support box  24  remains in the locked position and plate support box  26  is thrown off of blanket support box  24  by actuator  37  such that plate cam  45  does not contact blanket cam  144  and plate cam  146  comes into contact with alignment stop  40 . One or more rollers of inking and dampening apparatus  18  and alignment stop  40  have been moved away from plate cylinder  116 . A plate on plate cylinder  116  may be removed and replaced with a replacement plate. In this thrown off arrangement, maintenance operations that do not require a cutoff change may be performed on cylinders  12 ,  114 ,  116 . 
       FIG. 5  shows printing unit  10  shown in  FIG. 4  in a plating arrangement. Plate cylinder  116  is back into contact with blanket cylinder  114 . Plate cylinder  116  is in position for a plating operation and the replacement plate may be secured on plate cylinder  116  by rotating plate cylinder  116  and contacting the replacement plate with blanket cylinder  114 . Plate cam  45  is back into contact with blanket cam  144 . Alignment stop  10  is in the non-aligning position and is not contacting plate cam  146 . After the replacement plate is mounted on plate cylinder  116 , the one or more rollers of inking and dampening apparatus  18  may be brought back into contact with plate cylinder  116  and printing unit  10  may resume printing. 
     In alternative embodiments, blanket cams  43 ,  44  ( FIG. 1 ) may be replaced by a single cam and blanket cams  143 ,  144  may be replacement by a single cam. 
     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.