Abstract:
An inking unit for printing machines comprises a plate cylinder and a plurality of plate inking rollers being continuously fed with ink by a plurality of inking rollers; seen in direction of rotation of the plate cylinder, the primary ink flow being supplied to the first group of plate inking rollers, and a secondary ink flow being supplied to a subsequent group of plate inking rollers, and comprising the possibility of improving the adjustment of the inking unit to the respective print job by forming two groups of plate inking rollers.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an inking unit for printing machines, or printing presses. Such printing machines, or printing presses, typically comprise a plate cylinder and a plurality of plate inking rollers which are substantially continuously fed with ink by a plurality of inking rollers. A primary ink flow is supplied to a first group of plate inking rollers and a secondary ink flow is supplied to a subsequent, second group of plate inking rollers, as viewed in the direction of rotation of the plate cylinder. 
     2. Background Information 
     In a known inking unit comprising four plate inking rollers, the last two plate inking rollers, as viewed in the direction of rotation of the plate cylinder, generally serve to uniformly distribute the ink film and to transfer only a small amount of ink. Very good results can usually be obtained when using such an inking unit for top-grade print jobs having large areas to be printed. The German Laid Open Patent Application No. 21 06 655 discloses such an inking unit in which the amount of ink available on the last two plate inking rollers, as viewed in the direction of rotation of the plate cylinder, may be varied by an additional disengageable roller so that a varying amount of ink can be applied onto the printing plate via those two rollers. Such an inking unit is essentially designed to produce a top-grade print quality, meaning that, in practice, such an inking unit is generally too sophisticated for relatively ordinary print jobs with which, for example, ink plays only a subordinate role. In this respect, unnecessary costs may result. 
     OBJECT OF THE INVENTION 
     On the basis of the background set forth above, the objects of the invention are to improve the adaptability of an inking unit to a respective print job, to reduce the consumption of energy and to minimize the wear and tear of an inking unit. 
     SUMMARY OF THE INVENTION 
     According to the invention, the above objects are achieved in that the inking rollers feeding the subsequent, second group of plate inking rollers with a secondary ink flow are preferably mounted so as to be disengageable from the inking rollers feeding the first group of plate inking rollers with the primary ink flow such that the ink supply to the subsequent group of inking rollers is interrupted, and that the subsequent group of plate inking rollers is disengaged from the plate cylinder while the machine is running. This solution makes it possible to disengage part of the inking unit and to ink the printing plate only by means of, for example, two remaining plate inking rollers. Such a reduced number of plate inking rollers may tend to be sufficient with a number of straightforward print jobs so that, by disengaging the partial inking unit, drive energy is saved and wear and tear of the inking rollers is avoided. 
     A further advantage of the invention is the fact that such a &#34;reduced&#34; inking unit can be adjusted to the respective print job more quickly, thus producing less waste. It also reacts to inking changes more quickly and permits shorter times for correction work. 
     Furthermore, the development of heat, which normally tends to occur as a result of squeezing, or pressing, of various rollers, is reduced in the area of the inking rollers standing still, which is advantageous to printing. Thus, with each print job and each individual printing ink, the pressman can decide as to whether the highest possible inking quality is required or whether a respective print job may be effected with an inking unit having less inking rollers while, at the same time, still producing an optimum print result. 
     In an advantageous specimen embodiment of the invention, the inking unit is characterized in that, via an adjusting means, the first inking roller of the secondary ink flow is disengaged from the inking roller provided upstream thereof, that, as viewed in the direction of rotation of the plate cylinder, preferably the last two plate inking rollers, from among preferably four plate inking rollers, are disengaged, and that an intermediate roller provided between the second and the third plate inking rollers is lifted from the second plate inking roller. Thus, this specimen embodiment essentially requires only one additional adjusting means for the first plate inking roller of the secondary ink flow. The disengagement of the third and fourth plate inking roller may be effected via the ordinary adjusting means of the plate inking rollers; the third plate inking roller, in its disengaged position, lifting up an intermediate roller which may possibly be provided and disengages that intermediate roller from the second plate inking roller. 
     In other words, the intermediate roller is preferably configured such that the same will be passively disengaged from the second plate inking roller in response to the disengagement of the third and fourth plate inking rollers. According to this specimen embodiment of the invention, the objects of the invention are solved with little technical efforts and at low cost, an adjustment to the respective set-up of the inking unit being readily effected. 
     In summary, one aspect of the invention resides broadly in a printing press comprising: a frame; a plate cylinder being rotatably mounted on the frame; an ink reservoir for holding a supply of ink; an inking mechanism for transferring the ink between the ink reservoir and the plate cylinder during operation of the printing press; the inking mechanism comprising a plurality of inking rollers, at least one ink fountain roller and at least one transfer roller for transferring ink between the ink fountain roller and at least one of the plurality of inking rollers; a plurality of ink applicator rollers for being engaged with the plate cylinder and for applying ink to the plate cylinder; the plurality of ink applicator rollers comprising a first set of at least one ink applicator roller and a second set of at least one ink applicator roller; means for simultaneously providing a first stream of ink to the first set of at least one ink applicator roller and a second stream of ink to the second set of at least one ink applicator roller; and means for interrupting one of: the first stream of ink to the first set of at least one ink applicator roller; and the second stream of ink to the second set of at least one ink applicator roller; during operation of the printing press. 
     Another aspect of the invention resides broadly in a method of operating a printing press and printing a printed product, the method comprising the steps of: providing a frame; providing a plate cylinder and rotatably mounting the plate cylinder on the frame; providing an ink reservoir for holding a supply of ink; providing an inking mechanism for transferring the ink between the ink reservoir and the plate cylinder during operation of the printing press; the step of providing an inking mechanism further comprising the step of providing a plurality of inking rollers, at least one ink fountain roller and at least one transfer roller for transferring ink between the ink fountain roller and at least one of the plurality of inking rollers; providing a plurality of ink applicator rollers for being engaged with the plate cylinder and for applying ink to the plate cylinder; configuring the plurality of ink applicator rollers to comprise a first set of at least one ink applicator roller and a second set of at least one ink applicator roller; providing means for simultaneously providing a first stream of ink to the first set of at least one ink applicator roller and a second stream of ink to the second set of at least one ink applicator roller; and providing means for interrupting one of: the first stream of ink to the first set of at least one ink applicator roller; and the second stream of ink to the second set of at least one ink applicator roller; during operation of the printing press; the method further comprising the additional steps of: initiating operation of the printing press; transferring ink between the ink reservoir and the plate cylinder; the transferring step comprising the step of transferring the ink between the ink fountain roller and at least one of the plurality of inking rollers; engaging the plurality of inking rollers with the plate cylinder; applying ink to the plate cylinder by means of the plurality of inking rollers; simultaneously providing a first stream of ink to the first set of at least one ink applicator roller and a second stream of ink to the second set of at least one ink applicator roller; and interrupting one of: the first stream of ink to the first set of at least one ink applicator roller; and the second stream of ink to the second set of at least one ink applicator roller; during operation of the printing press. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A specimen embodiment of the invention is schematically illustrated in the accompanying drawings, wherein: 
     FIG. 1 is a schematic view of the inking unit showing the inking of the printing plate via four plate inking rollers, 
     FIG. 2 is a schematic view of an inking unit showing the inking of the printing plate via the first two plate inking rollers, and 
     FIG. 2a is substantially the same view as FIG. 2 but illustrates additional components. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In a known manner, the inking unit shown in FIG. 1 comprises an ink fountain 1 having a fountain roller 2 and ink rollers 3 through 9 supplying the primary ink flow to, as viewed in the direction of rotation of the plate cylinder 10, the first two plate inking rollers 11 and 12. The last two plate inking rollers 13 and 14 are supplied with a secondary ink flow by the inking rollers 15 through 17. In the specimen embodiment shown, an intermediate roller 18 is provided between the second plate inking roller 12 and the third plate inking roller 13. Thus, generally the ink is divided at the inking roller 8 into a primary and a secondary ink flow so that, due to the direction of rotation of the individual inking rollers, the primary ink flow is supplied to the first group of plate inking rollers 11 and 12. 
     With reference to FIG. 2a, the printing press preferably includes a vibrator roller 23, which may be alternatively termed a &#34;transfer roller&#34;. 
     In accordance with a preferred embodiment of the present invention, the rollers of the inking unit may preferably be arranged as follows: 
     roller 3 is mounted to receive ink from fountain roller 2, via vibrator roller 23, and is engaged with roller 4; 
     roller 4 is engaged with roller 5; 
     roller 5 is engaged with roller 6; 
     roller 6 is engaged with roller 7; 
     roller 7 is engaged with roller 8; 
     roller 8 is engaged with roller 9; 
     roller 9 is engaged with plate inking rollers 11 and 12; 
     roller 15 is selectively engageable and disengageable with both roller 8 and roller 16; 
     roller 16 is engaged with roller 17; 
     roller 17 is engaged with plate inking rollers 13 and 14; and 
     intermediate roller 18 is engaged with plate inking roller 13 and is selectively engageable and disengageable with roller 12. 
     Thus, in accordance with the present invention, roller 8 preferably serves as a point of bifurcation for the primary and secondary ink flows, wherein the primary ink flow eventually reaches plate inking rollers 11 and 12 and the secondary ink flow eventually reaches plate inking rollers 13 and 14. In this manner, as shown in FIG. 1, the plate cylinder 10 can receive ink from both sets of plate inking rollers 11,12 and 13,14. 
     If, in accordance with a preferred embodiment of the present invention, the printing plate of the plate cylinder 10 is to be inked only via the first group of inking rollers 11 and 12, the two plate inking rollers 13 and 14 of the second group of plate inking rollers can, as shown in FIG. 2, preferably be lifted from the plate cylinder 10 via disengaging means provided for the plate inking rollers. A schematic representation of such disengaging means is indicated at 24 in FIG. 2a. In so doing, the intermediate roller 18 may preferably be mounted with its journals 19 in a sliding bearing 20 provided on both sides thereof so that the rolling contact between the plate inking roller 12 and the intermediate roller 18 is interrupted. Furthermore, the first inking roller 15 of the secondary ink flow, which may be alternatively termed a &#34;bridge roller&#34;, is lifted in its bearing 22 via an adjusting means 21, which may be a servomotor, so that the outer cylindrical surface of the first inking roller 15 is not in contact with the outer cylindrical surface of the inking roller 8. Thus, the inking supply to the group of plate inking rollers 13 and 14 via the inking rollers 15 through 17 and the intermediate roller 18 can preferably be interrupted in the manner described immediately above. If desired, the drive of those rollers may also be switched off so that, given certain print jobs, said rollers may stand still after having been washed. This may be effected by disengaging the drive gear (not illustrated) of the inking roller 17, for example. 
     Thus, in accordance with a preferred embodiment of the present invention, as shown in FIGS. 2 and 2a, the inking unit can essentially be configured for selectively interrupting the secondary ink flow to the second set of plate inking rollers 13,14. In this regard, the first inking roller of the secondary ink flow, designated as roller 15, is preferably slidably mounted in a bearing 22 and is preferably slidably displaceable by means of an adjusting means 21. Such an adjusting means may include, for example, a servomotor or another suitable actuator arrangement known to those of ordinary skill in the art. Thus, to interrupt the secondary ink flow, roller 15 can preferably be slidably displaced away from roller 8 so that roller 8 will subsequently transfer ink only to roller 9. Additionally, plate inking rollers 13 and 14 may preferably be disengaged from plate cylinder 10, by means of the disengaging apparatus 24 illustrated in FIG. 2a. Also, if the inking unit includes an intermediate roller 18 positioned between, as viewed in the direction of rotation of the plate cylinder, the last plate inking roller 12 of the first set of plate inking rollers 11,12 and the first plate inking roller 13 of the second set of plate inking rollers 13,14, such an intermediate roller 18 can preferably have its journals 19 slidably mounted in a bearing 20. As such, intermediate roller 18 can preferably be configured such that, upon disengagement of plate inking roller 13 from plate cylinder 10, intermediate roller 18 will essentially be pushed upward in its bearing 20 by plate inking roller 13 and will become disengaged from plate inking roller 12. Thus, such an action can preferably ensure that the secondary ink flow is completely prevented from reaching plate cylinder 10 and that, if desired, the rollers associated with the secondary ink flow can remain non-driven during an operation of the printing press which involves only the application of the primary ink flow to the plate cylinder 10. 
     It should be understood that, in accordance with the present invention, it is conceivable that the inking unit and associated rollers could be configured to also, optionally, interrupt the primary ink flow to the plate cylinder, instead of the secondary ink flow. For example, the first set of plate inking rollers 11,12 could be selectively disengageable from the plate cylinder 10 in a manner similar to the second set of plate inking rollers 13,14. Additionally, it should be understood that the present invention is essentially applicable with other numbers of plate inking rollers, such as two, three, five, or even six or more plate inking rollers, providing that at least one plate inking roller is configured to receive a primary ink flow and that at least one other plate inking roller is configured to receive a secondary ink flow. 
     A printing press frame, on which the rollers and cylinders described above may be mounted, is indicated at 26 in FIG. 2a. 
     Also, schematically indicated at 28 in FIG. 2a is a control arrangement which may preferably be employed to control adjusting means 21 and disengaging apparatus 24. Control arrangement 28 may preferably be configured to control adjusting means 21 and disengaging apparatus either separately or in a coordinated manner. 
     One feature of the invention resides broadly in the inking unit for printing machines comprising a plate cylinder and a plurality of plate inking rollers being continuously fed with ink by a plurality of inking rollers; seen in direction of rotation of the plate cylinder, the primary ink flow being supplied to the first group of plate inking rollers and a secondary ink flow being supplied to a subsequent group of plate inking rollers, characterized in that the inking rollers 15 through 17 supplying the secondary ink flow to the subsequent group of plate inking rollers 13, 14 are mounted so as to be disengaged from the inking rollers 3 through 9 supplying the primary ink flow to the first group of plate inking rollers 11, 12 such that the ink supply to the subsequent group of inking rollers 13, 14 is interrupted, and that the subsequent group of plate inking rollers 13, 14 is disengaged from the plate cylinder while the machine is running. 
     Another feature of the invention resides broadly in the inking unit, characterized in that, via an adjusting means 21, the first inking roller 15 of the secondary ink flow is disengaged from the inking roller 8 provided upstream thereof, that, seen in direction of rotation of the plate cylinder 10, the last two plate inking rollers 13, 14 - from among four plate inking rollers 11 through 14 - are disengaged, and that the intermediate roller 18 provided between the second and the third plate inking roller 12, 13 is lifted from the second plate inking roller 12. 
     An example of an arrangement for disengaging, or lifting, ink applicator rollers from a plate cylinder, including a control arrangement, may be found in U.S. Pat. No. 3,809,983 to Garber, entitled &#34;Variable Repeat-Length Web Press&#34;. 
     Examples of general components for printing presses, which may be utilized in accordance with the embodiments of the present invention, may be found in the following U.S. Pat. Nos. 5,010,820, which issued to Loffler on Apr. 30, 1991; and 5,081,926, which issued to Rodi on Jan. 21, 1992. 
     Examples of arrangements for disengaging, or lifting, ink applicator rollers from a plate cylinder, including control arrangements, may be found in the U.S. Patents listed immediately above and also in U.S. Patent No. 3,809,983 to Garber, entitled &#34;Variable Repeat-Length Web Press&#34;. 
     All, or substantially all, of the components and methods of the various embodiments may be used with at least one embodiment or all of the embodiments, if any, described herein. 
     All of the patents, patent applications and publications recited herein, if any, are hereby incorporated by reference as if set forth in their entirety herein. 
     The details in the patents, patent applications and publications may be considered to be incorporable, at applicant&#39;s option, into the claims during prosecution as further limitations in the claims to patentably distinguish any amended claims from any applied prior art. 
     The appended drawings, in their entirety, including all dimensions, proportions and/or shapes in at least one embodiment of the invention, are, if applicable, accurate and to scale and are hereby incorporated by reference into this specification. 
     The invention as described hereinabove in the context of the preferred embodiments is not to be taken as limited to all of the provided details thereof, since modifications and variations thereof may be made without departing from the spirit and scope of the invention. 
     LIST OF REFERENCE NUMERALS 
     1 ink fountain 
     2 fountain roller 
     3 inking roller 
     4 inking roller 
     5 inking roller 
     6 inking roller 
     7 inking roller 
     8 inking roller 
     9 inking roller 
     10 plate cylinder 
     11 plate inking roller 
     12 plate inking roller 
     13 plate inking roller 
     14 plate inking roller 
     15 inking roller 
     16 inking roller 
     17 inking roller 
     18 intermediate roller 
     19 journal 
     20 sliding bearing 
     21 adjusting means 
     22 bearing 
     23 vibrator roller 
     24 disengaging apparatus 
     26 printing press frame 
     28 control arrangement