Abstract:
A color ink supply device for an ink ductor in a rotary printing press achieves an even color distribution on the ink ductor. A plurality of ink supply devices are arranged axially along the ink ductor. Each ink supply device includes a main chamber and may also include a pre-chamber. A doctor blade device may also be utilized.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an ink unit with an ink supply device for an ink ductor. A plurality of ink feed devices are arranged next to each other in an ink supply strip. Each ink feed device has an ink feed line which supplies ink to a chamber located at the ink ductor. 
     DESCRIPTION OF THE PRIOR ART 
     A device for applying ink to a rotatable cylinder of a rotary printing press is known from DE 28 16 881 A1. Ink is supplied by a pump to a conduit via a bore, which bore branches into two flow paths and meets the surface of the rotatable ink roller in the radial direction. A plurality of pumps are arranged next to each other. 
     U.S. Pat. No. 2,377,482 A describes an ink applicator strip for a forme cylinder of a rotogravure press. This ink applicator strip has a plurality of slit-shaped nozzles, wherein adjoining nozzles are connected in the area of their outlet opening. 
     U.S. Pat. No. 4,461,209 A shows an ink supply device for a forme cylinder, having an ink supply strip. This ink supply has several main chambers, which are connected at their ends by overflow openings. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is directed to providing an ink unit with an ink supply device for an ink ductor. 
     In accordance with the present invention, this object is attained by providing an ink supply device that has a plurality of ink feed devices. These ink feed devices are arranged next to each other in an ink supply strip. Each ink feed device has an ink feed line and at least one main chamber for each ink color zone of the ink ductor. The ends of the main chambers terminate at the ink ductor. 
     The advantages which can be obtained by the present invention primarily consist in that an even ink distribution for each ink pump unit and color zone is achieved on the surface of the ink ductor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention is represented in the drawings and will be described in greater detail in what follows. 
     Shown are in: 
     FIG. 1, a longitudinal section through an ink supply strip with pre-chambers and main chambers taken along line I—I of FIG. 2 in a partial representation, and in 
     FIG. 2 a longitudinal section through an ink supply strip with pre-chambers and main chambers taken along line II—II of FIG.  1  and with the additional representation of an ink ductor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An ink supply device  02 , fastened on the press frame, is arranged in cooperation with an ink ductor  01  of an ink unit, which ink unit is not specifically represented, of a rotary printing press. The ink supply device  02  extends in length at least for one-quarter of the width of the ink ductor  01  in its axial direction and consists at least of an ink supply strip  03  with a number, for example six to eight, of ink feeds  05 ,  06 ,  07  for color zones arranged next to each other, as well as of a closing strip  08  of equal length arranged on the ink supply strip  03 . Each one of the ink feeds  05  to  07  located on the ink supply strip  03  has an ink feed line  09  coming from a controllable ink pump, not represented, which ink feed line  09  is adjoined, in the flow direction A of the ink, by a pre-chamber  11 , which, in turn, leads to an inlet  12  of a main chamber  13 . The main chamber  13  is shaped into a slit-shaped nozzle  16  at its discharge end  14  close to the ink ductor  01 . The main chambers  13  are separated from each other by strips  17 . 
     The pre-chamber  11  extends horizontally and at right angles to a longitudinal axis  20  of the bore or ink feed line  09  as seen in FIG. 2, and has a width “b”, for example “b”=40 mm, which corresponds at least to twice the width or diameter “d”, for example “d”=10 mm, of the ink feed line  09 . At its inlet  12 , the adjoining main chamber  13  is of the same width “b” and then widens, viewed in the flow direction A, to a width “c” at its end  14 , for example “c”=52 mm. The width of the strips  17 , which, as shown in FIG. 1, are embodied in a wedge shape, decreases by the same amount. 
     With increasing widening “b”, “c” of the main chamber  13 , its thickness “e” is reduced, viewed in the flow direction A, for example “e”=1 mm as seen in FIG.  2 . 
     The ink can also be supplied in a “clocked” or “pulsed” manner to the ink supply device  02  from the controllable ink pump, which is not specifically represented. 
     The ink feed line, pre-chamber and main chamber  09 ,  11 ,  13 , respectively in the ink supply strip  03  are easily accessible, for example for cleaning purposes, and are bordered, or closed, by the closing strip  08 . 
     In accordance with a variation of the above-described preferred embodiment, each main chamber  13  has an overflow opening  18  for ink to the adjoining main chamber  13  on its discharge end  14  near the strip. This overflow opening  18  can be provided by shortening the strips  17  at the end  14  of the main chamber  13 , as shown in FIG.  1 . 
     The overflow opening  18  has a height “I”, for example “I”=2 mm, and a depth “y”, for example “y”=0.6 mm, at the front, and a depth “x”, for example “x”=0.5 mm, at the end near the ink ductor  01 , and therefore a cross section of “y”·“I”=1.2 mm 2 . 
     The ratio of the outlet cross section b”·“e” of the pre-chamber  11  to an outlet cross section “c”·“x” at the discharge end  14  of the slit-shaped nozzle  16  is greater than 1 and less than 2, preferably (b·e)/(c·x)=1.4 to 1.6. 
     The ratio of the height “I” of the overflow opening  18  to a height L, for example L=60 mm, of the main chamber  13  is greater than 0.01 and less than 0.03, preferably I/L=0.02. 
     The ink supply device  02  is preferably arranged in such a way in respect to the ink ductor  01 , that each of the main chambers  13  extends approximately in the vertical direction, and that the slit-shaped nozzles  16  at the discharge end  14  each point in an approximately tangential direction toward the ink ductor  01 . The working direction of rotation F of the ink ductor  01  extends in the same direction with the flow direction A of the ink. 
     In accordance with another variation of the preferred embodiment of the ink supply strip  03 , a pre-chamber can have a width which is greater in comparison with the above-described first embodiment that is shown in FIG. 1, for example up to five times the diameter “d” of the ink feed line  09 . Thus, an inlet  12  of a main chamber  13  is wider, and strips  17  arranged between the main chambers  13  are narrower, in comparison to those in the first preferred embodiment. The prerequisite here is that an angle α formed at the discharge end  14  of the main chamber  13  between a flank  19  of the main chamber  13  and a horizontal line  21  be less than 90°. 
     The ink supply device of the present invention functions as follows: because of the arrangement of the pre-chamber  11 , the ink flow from ink feed line  09  is already broadly distributed prior to it flowing into the main chamber  13 . The broad distribution of the ink is initially obtained because a cross-sectional area of the ink feed line  09  leading to the pre-chamber  11  is greater than a cross-sectional surface “e”·“b” of an outlet  29  of the pre-chamber  11  into the main chamber  13 . Because of this, the pre-chamber  11  is always filled with ink and is therefore used as an ink reservoir. An even ink distribution in each color zone on the ink ductor  01  thus takes place. This means that an even ink film forms over each of the color zones on the surface  31  of the ink ductor  01 . The overflow openings  18 , located at the discharge end  14  of the main chamber  13 , through which a possible compensation of the amounts of ink can occur, are therefore advantageous for providing an even ink distribution over the width of the ink metering roller  01 . 
     In accordance with a further preferred embodiment of the present invention, a doctor blade arrangement  23  is assigned to the ink supply device  02  which doctor blade arrangement  23  is located, in the working direction of rotation F of the ink ductor  01 , after the ink supply device  02 , as seen in FIG. 2. A doctor blade  24  can be placed at a positive contact angle against the ink ductor  01 . Positive contact angle of the doctor blade  24  against the ink ductor  01  means that the doctor blade  24  rests against the surface  31 , or is slight spaced apart from it, while pointing with the front face  27  in the working direction of rotation F. 
     The doctor blade  24  extends approximately tangentially with respect to the ink ductor  01 . The doctor blade  24  is arranged so that, for example, it can be clamped in place between the closing strip  08  and a support strip  26  located on the closing strip  08 . In the area of its front edge  27 , the doctor blade  24  can be adjustable by means of arresting devices, for example screws  28 . 
     While preferred embodiments of a color supply device for a color ductor of a rotary printing press in accordance with the present invention have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that a number of changes in, for example, the overall size of the ductor roller, the type of rotary press the ductor is used with, and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the following claims.