Patent Publication Number: US-6336403-B1

Title: Dampening system for printing machines

Description:
BACKGROUND OF THE INVENTION 
     In lithographic printing, it is desirable to have a thin layer of wetting liquid applied to the plate cylinder to enhance the application of ink and to better define the printing and non-printing areas of the printing plate. See U.S. Pat. Nos. 3,701,316 and 4,290,260, for example. 
     Existing devices which perform the dampening function normally utilize a system of rolls wherein a dampening roll provides a layer of liquid to be distributed by surface contact to a plurality of rolls in the system as the dampening roll is exposed to a reservoir of fluid. The system is shut down in times of non-printing. When the system is started again, substantial time is taken to obtain the proper ink and water balance on the rolls as the fountain roll again starts to move fluid from the reservoir over the surfaces of the rolls to the printing plate. As the system starts up, substantial amounts of paper are wasted until the ink-fluid balance is obtained. 
     It is therefore a principal object of this invention to provide a dampening system for printing machines wherein the fountain roll runs continuously in operative contact with the fluid reservoir, but where its surface contact with downstream rollers is interrupted when the printing system is discontinued. 
     A further object of this invention is to provide a dampening system for printing machines wherein the water accumulating on the surface of the fountain roll will go back into the fluid reservoir when the system is not printing and when it is not desirable to distribute fluid to the rolls of the system. 
     These and other objects will be apparent to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     A fluid dampening system for a printing machine has a frame and a printing roll on the frame for holding a circular printing plate. A fluid reservoir is on the frame and a fountain roll is on the frame and is partially immersed in the fluid reservoir. A second roll is on the frame and is normally in surface contact with the fountain roll. A third roll is on the frame and is normally in surface contact with the fountain roll. A plurality of additional rolls are on the frame sequentially in surface contact with each other and with the third roll and the printing roll so that when all of the aforesaid rolls are rotated and in surface contact with each other, fluid will be transferred from the surface of the fountain roll to the surface of the third roll and sequentially on the surface of the additional rolls to the surface of the printing roll. 
     A drive system on the frame connects the second roll and the third roll whereby the third roll drives the second roll which in turn drives the fountain roll. A linkage system is provided for breaking the fountain roll away from surface contact with the third roll while all the rolls are rotating to separate the fountain roll from surface contact with the third roll to prevent fluid from moving from a surface of the fountain roll to the third roll and to the rolls downstream from the third roll, while still permitting all the rolls to be simultaneously rotated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the machine of this invention; 
     FIG. 2 is an exploded side elevational view of the various rolls of the machine of FIG. 1; 
     FIG. 3 is an enlarged scale perspective view of the fluid reservoir, the fountain roll and adjacent rolls with the gear segments removed; 
     FIG. 4 is an enlarged scale side elevational view taken on line  4 — 4  of FIG.  1  and shows the fountain roll in its inoperative position; 
     FIG. 5 is a view similar to that of FIG. 4 but shows the fountain roll in its operative position; and 
     FIG. 6 is a view similar to that of FIG. 3 but shows the gear segments in place. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With reference to FIG. 1, an offset printing press  10  of conventional construction has second-color auxiliary print unit  12  which slidably receives the dampening roll system  14  of this invention. The conventional rails for selectively receiving the roll system  14  within the unit  12  have been omitted from the drawings but are conventional in nature and well within the skill of one in the art. The machine  10  has a conventional frame  16 , and the dampening roll system  14  has a sub-frame  18  which is best shown in FIGS. 4 and 5. 
     A fluid reservoir  20  shown best in FIGS. 3 and 6 is mounted on the frame. A dampening roll  22  is mounted on sub-frame  18  and is positioned so as to be partially immersed into the fluid  23  of reservoir  20 . A second roll sometimes called a metering roll  24  is mounted on the sub-frame  18  and is parallel to and has surface contact with dampening roll  22 . Second roll  24  is operationally connected by gear  26 , idler gear  28  and gear  30  to a third roll  32  which is normally in surface contact with fountain roll  22  at nip point  33  (FIG.  3 ). A conventional printing roll  34  is mounted on sub-frame  18  and has a gear  34 A associated therewith. A printing plate  36  is mounted on the surface of roll  34  in conventional fashion. An intervening transfer roll  40  is mounted in parallel fashion and has surface contact with roll  32 ; and a further transfer roll  42  is disposed on frame  18  in parallel fashion to roll  40  and is in surface contact therewith. A further transfer roll  44  has gear  44 A associated therewith and is positioned parallel to and in surface contact with roll  42 . Similarly, a further transfer roll  46  is positioned in parallel fashion to roll  44  and is in surface contact therewith. Roll  46  has gear  46 A associated therewith in mesh with gear  44 A on roll  44 . A conventional spring-pressure element  48  is mounted on roll  40  to yieldingly hold roll  40  in pressure contact with both rolls  32  and  42  as best shown in FIG.  2 . The gears  46 A on roll  46  are also in mesh with the gears  34 A on printing roll  34 . 
     With reference to FIGS. 4 and 5, a link assembly  50  is mounted on sub-frame  18  and includes an L-shaped link  52  which is pivoted to sub-frame  18  by pivot pin  54 . A conventional roller  56  is mounted on the lower end of link  52  and engages an inner end of arm  58  which is pivotally secured to the frame  12  by pin  59 . Manually operated handle  60  is positioned with respect to arm  58  so that movement of the handle  60  from the position shown in FIG. 5 to the position of FIG. 4 will cause the fountain roll  22  to separate from surface contact with the third roll  32  as shown in FIG. 4, and as will be explained in more detail hereafter. A spring  62  is secured by one of its ends to link  52  with the other end being secured to sub-frame  18  so as to yieldingly hold the link  52  in the normal operating position for the fountain roll  22  as shown in FIG.  5 . 
     A horizontal link  64  is pivotally secured by its ends through pivot pins  65 , with one end being pivotally secured to the upper end of link  52  by a first pin  65 , and the other end being connected by a second pin  65  to axle clamp  66 . The axle clamp is also rigidly secured to the eccentric shaft  68  of fountain roll  22 . 
     In operation, the handle  60  is used to control the dampening roll system  14  and the unit  12  through various stages of the printing operation. However, the two operational positions most relevant to this invention are shown in FIGS. 4 and 5. It should be noted that suitable operational power is supplied to roll  34  whereupon the rolls  46  and  44  are rotated by reason of the intermeshed gears  34 A with  46 A, and  46 A with gears  44 A. Roll  44  is rotated by intermeshed gears  44 A and  46 A, and rotates roll  42  surface contact therewith. Roll  40  is rotated by reason of its surface contact with roll  42 . Roll  32  is rotated through its surface contact with roll  40 . The rotation of roll  32  imparts rotation motion to roll  24  through gears  30 , idling gear  28  and gear  26  (FIG.  2 ). Roll  24  imparts rotational motion to fountain roll  22  through its surface contact with roll  22 . 
     When the handle  60  is in the position shown in FIG. 5, the spring  62  maintains the links  52  and  64  and axle clamp  66  in a position to maintain the fountain roll  22  in surface contact with roll  32 . When in that position, the fountain roll  22  acquires liquid on the surface thereof from the reservoir  20 . Water from the reservoir is transmitted from roll  22  to third roll  32  through the surface contact between the two rolls. The moisture on the surface of roll  32  is thereafter sequentially transmitted to the intervening transfer rolls  40 ,  42 ,  44 ,  46  and  34  by the surface contact therebetween whereupon an appropriate film of fluid is deposited on printing plate  36 . 
     When it is desired to interrupt the printing activity, the handle  60  is moved to the position of FIG. 4 which causes the link assembly  50  to move from the position of FIG. 5 to the position of FIG.  4 . This causes the rotation of the eccentric shaft  68  for fountain roll  22  to move from the position of FIG. 5 to FIG. 4 which in turn separates the rolls  22  and  32  at the nip point  33  as best shown in FIG.  4 . In this situation, all of the rolls in the system, including the intervening rolls  40 ,  42 ,  44  and  46  which extend between roll  32  and roll  34  continue to rotate. However, no moisture or liquid is transferred during that stage of the operation from fountain roll  22  because it has no surface contact with roll  32 . Any excess moisture accumulating on roll  22  falls by gravity back into the reservoir  20 . 
     When it is desired to resume printing, the roll  22  can be immediately put in its operating position by moving the handle  60  from a position in FIG. 4 back to the position in FIG.  5 . No time is lost for the fountain roll to accumulate a layer of moisture on its outer surface because that moisture is already there through its constant rotation during the inoperative printing stage. 
     Master control handle  60 A (FIG. 1) which controls all operational phases of the press  10  can also be used by suitable connections (not shown) to move the roll  22  back and forth between the inoperative position of FIG. 4 to the operative position of FIG.  5 . 
     From the foregoing, it is seen that the present invention substantially speeds up the process of going from the inoperative to the operative dampening mode, and substantial time is saved because the fountain roll is always ready to go to its operative position. 
     Thus, this invention achieves at least all of its stated objectives.