Abstract:
The present invention is an adjustable oscillating ink form or roller that moves freely back and forth along its axis of rotation to create a more efficient inking of the printing plate of a high-speed web printing press by allowing for a more even distribution of ink onto the printing plate in a more consistent manner. The back and forth oscillation is especially useful in preventing image “ghosting” that forms on the printed page when the ink thickness diminishes.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to the inking of high-speed web printing presses. High-speed web printing is a widely used printing technique where the inked image is transferred from a plate to a rubber blanket, then to the printing surface. Some advantages of high speed web printing compared to other printing methods are consistent high image quality and production of sharper, cleaner images and type than letterpress printing for the reason that the rubber blanket conforms to the texture of the printing surface. Additionally, the production of the printing plates is quick and easy and the printing plate life is longer than on direct lithographic presses, since there is no direct contact between the plate and the printing surface. 
         [0002]    The present invention is an oscillating ink form, which is designed as an intermediary roller between the inking roller and the high speed plate. The oscillating ink form is designed differently than prior inking forms. The present invention is permitted to move freely back and forth within preset lateral motion limiters, to allow a more even distribution of the ink onto the high speed plate that prints on the paper. 
         [0003]    One problem with earlier ink forms is that these ink forms were static, i.e., locked in a single position, and thus, unable to laterally move within the confines of the horizontal dimensions of the press. In this manner, ink being deposited on the intermediate roller or on the rubber blanket was unevenly distributed across the printing surface. Due to the non-oscillating nature of earlier ink forms “ghosting” occurred on the printed page, which is a slightly offset secondary image of the primary image. “Ghosting” can occur because the thickness of the deposited ink diminishes during transference. Therefore a need exists for an ink form that prevents the occurrence of “ghosting” by employing a laterally offset motion for the indirect transference of the ink for the high speed presses to avoid ink thickness differences on either the secondary transfer roller or the rubber blanket. 
         [0004]    A need also exists for an ink form roller that achieves a more uniform inking of the inking transfer roller, and ultimately the printing plate (or rubber blanket) by allowing for a slight lateral motion of the inking form along its axis. This will achieve a more even distribution of ink onto the printing plate in a continuing, consistent manner and is especially useful in preventing horizontal and vertical lines that form when the ink thickness diminishes. Moreover, a need also exists for an ink form that prevents the fading of bold letter characters and reprinted photos. The present invention will permit minimal lateral displacement of the inking form along its axis (support shaft) within preset motion limiters to create the more uniform distribution of ink across the width of the press assembly. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention is an oscillating ink form used in place of the standard large ink form, or the outside ink form, in the ink train of a high-speed printing press. The benefit of using an oscillating ink form is to create a more uniform distribution of ink across the width of the print rollers of the press and to reduce or eliminate “ghosting” resulting in better print quality. 
         [0006]    The ink form roller is assembled using a hollow core, an elongated shaft, a pair of washers, two split collar motion limiters, a pair of linear rotary bearings and a pair of snap rings. A rubber covering is applied to the outer surface of the core to form the ink form roller. The ink form roller is mounted on a stationary solid shaft that runs through the hollowed middle of the ink form roller. When installed in the ink train of the high-speed press, the shaft is bolted to the frame, so that the roller can spin freely about the pair of linear rotary bearings, as well as travel back and forth, i.e., oscillate, along the rotational axis of the ink form roller within lateral motion limits set by the pair of split collar motion limiters. This is accomplished without any movement of the static shaft, although the ink form roller rotates at press speed. 
         [0007]    It is an object of the present invention to have the pair of split collar motion limiters positioned at substantially identical distances outward of the ink form roller core along the stationary shaft to allow the ink form roller to freely oscillate back and forth within the distance limited by the collars to provide a more uniform ink distribution to the transference roller and to the printing form. The ink form roller will rotate at machine speed, oscillating between the collars in following the associated drive roller, to distribute the ink along the desired ink width of the ink transference rollers of the press. 
         [0008]    It is another object of the present invention to have an ink form roller where the amount of the oscillation is adjustable in accordance with the placement of the paired split collar motion limiters so that the ink form roller may oscillate within a range of ¼ of an inch to 1 inch or more, according to the needs of the user. 
         [0009]    Other features and advantages of the invention are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0010]    For the purpose of illustrating the invention, there is shown in the drawing a form which is presently preferred; it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
           [0011]      FIG. 1  is a partial cutaway side view of the oscillating ink form roller assembly of the present invention. 
           [0012]      FIG. 2  is a schematic view of the series of rollers from the ink fountain roller to the plate and blanket cylinder rollers. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The following detailed description is of the best presently contemplated mode of carrying out the invention. The description is not intended in a limiting sense, and is made solely for the purpose of illustrating the general principles of the invention. The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawing. 
         [0014]    As illustrated in  FIG. 1 , the oscillating ink form system  10  is assembled using a hollow core  14 , which is cylindrical in shape, about which a rubber cover  16  is applied to create the ink form or roller  12 . A solid elongated shaft  18 , about which the hollow core  14  and rubber covering  16  will rotate, extends through the core  14 . In order that the ink form or roller  12  can rotate about the shaft  18 , a pair of linear rotary bearings  20   a,    20   b  are press-fitted into the cylindrical hollow space within the core  14  a predetermined distance inward from the respective rims of both ends of the core  14  and a pair of snap rings  22   a,    22   b  are positioned into respective slots precut inside the core  14  to retain the liner rotary bearings  20   a,    20   b  in their predetermined positions during use of the form or roller  12 . 
         [0015]    Completing the assembly of the oscillating ink form system  10 , the shaft is inserted through the hollow core  14  of the ink form or roller  12 , through the central aperture of each of the linear rotary bearings  20   a,    20   b.  The ink form or roller  12  is centered on the shaft  18  and a pair of motion permitting washers or spacers  24   a,    24   b,  are placed outward and at either side of the ink form or roller  12  along the shaft  18 . Finally, a pair of split collar motion limiters  26   a,    26   b  are positioned along the shaft  18  outward from the ink form or roller  12  a predetermined distance such that the ink form or roller  12  is capable of both free rotation about, and limited lateral motion along the shaft  18 . The motion limiters  26   a,    26   b  can be located at any desired distance away from the ends of the ink form or roller  12  to permit the free oscillation within the limited lateral distance between the motion limiters  26   a,    26   b.  It is preferred, although not required, to position the motion limiters  26   a,    26   b  at positions that are equidistant from either the center or the ends of the shaft  18  so that the ink form or roller  12  performs its rotational translation symmetrically along the length of the shaft between the motion limiters  26   a,    26   b.  If non-symmetrical oscillation is required, the motion limiters  26   a,    26   b  may be positioned at unequal distances to accommodate this requirement. 
         [0016]    The ink form or roller  12 , which is rotationally mounted about the elongated shaft  18  that runs through the hollow center of the ink form or roller  12 , is installed onto the press by bolting the opposite ends of the shaft  18  to the high-speed printing press frame. With reference to  FIG. 2 , there may be a number of placements for the ink form rollers  12  of the present invention in the roller series for inking high-speed presses. Starting in the upper left with the ink fountain roller  32 , this roller transfers the ink from the fountain (not shown) to one or more of ink transfer rollers  34  utilizing intermediary ink oscillator rollers  36 . These ink oscillator rollers also are intermediate the ink transfer rollers  34  and the one or more ink form rollers  12  of the present invention. The ink form rollers  12 , in turn, contact the printing plate cylinder roller  38 , transferring the ink so that “ghosting” does not occur when the ink is transferred to the blanket roller  40  for printing on the desired print surface. 
         [0017]    Each of any ink form rollers  12  present in the ink train system for the press is driven rotationally by the adjacent ink oscillator roller  36  and also laterally as the ink oscillator rollers  36  move laterally in accordance with the preferred scope of motion set for the individual print job. In this manner the ink form or roller  12  will freely rotate at press speed, without impediment, about the fixed, stationary shaft  18  and oscillate back and forth along the shaft  18  within the limited lateral spacings of the motion limiters  26   a,    26   b.  It is important to not that the lateral motion of the ink form roller  12  may be set to mimic the ink oscillator rollers  36  or be set to limit to lateral motion of the roller. The lateral, oscillating motion of the ink form or roller  12  provides for the more even distribution of ink within the ink train of the high-speed press. 
         [0018]    The linear rotary bearings  20   a,    20   b  that are used to mount the may ink form or roller  12  to the shaft  18  are preferred to be made of aluminum alloy or stainless steel, are cylindrical in shape with a hollowed out core, are capable of self alignment when placed in the desired position, and may range in length (for the present application) from 3 inches up to 8 inches. The overall distance between each of the motion limiters  26   a,    26   b  is larger than the overall length dimension of the ink form or roller  12  and the washers  24   a,    24   b  to permit the uninhibited lateral motion, i.e., the free rotational oscillation, of the ink form or roller  12 . 
         [0019]    The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, the described embodiments are to be considered in all respects as being illustrative and not restrictive.