Abstract:
A dampening system has at least one dampening ductor or roller; a dampening agent bin or trough, which holds a dampening agent, a feeding device, and a return device. The feeding device includes at least one dampening agent distributing pipe that has a number of spaced openings. A number of these dampening agent distributing pipes are assigned to the dampening ductor or roller.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This patent application is the U.S. national phase, under 35 USC 371, of PCT/DE03/01330, filed Apr. 24, 2003; published as WO 03/097359 A1 on Nov. 27, 2003 and claiming priority to DE 102 22 294, filed May 18, 2002, the disclosures of which are expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed to dampening systems with devices for the inflow and for the return flow of a dampening agent. The dampening system includes at least one dampening ductor, a dampening agent tank, an inflow device and a return flow device.  
       BACKGROUND OF THE INVENTION  
       [0003]     Dampening systems are used in offset printing presses and in other printing systems. A dampening system consists of, for example, a dampening ductor, which may also be called a water tank roller, a dampening agent tank, and devices for supplying and returning dampening agent to and from the dampening agent tank. The dampening ductor or roller is typically partially immersed in the dampening agent contained in the dampening agent tank, picks up the dampening agent by a rotating movement, and transfers the dampening agent to further rollers of the printing group. To prevent interferences with the printing operation, it is important that the dampening agent taken up by the dampening ductor or roller has identical physical and chemical properties over the entire length of the roller.  
         [0004]     A dampening system in an offset printing press is described in DE 198 53 362 C1. A supply system for dampening agent, which has a plurality of spray nozzles over the roller length, is assigned to the dampening ductor in the axial direction of the ductor.  
         [0005]     A dampening system is known from DE 196 16 198 A1, which system has at least one dampening agent pickup roller. A dampening agent supply line is arranged above the dampening agent pickup roller, parallel with this roller, and extends over the roller&#39;s full length. On its underside, the supply line is provided with outlet openings, by the use of which a water curtain is formed when the supply line is charged with dampening agent.  
         [0006]     For use in removing deposits, such as ink particles, for example, from a dampening ductor or roller, DD 247 414 A1 proposes to press a stripping element against the surface of the roller with a pressure which is equal over the entire length of the roller.  
         [0007]     A dampening agent recirculating system for offset printing presses is described in EP 0 638 417 A1. In this case, a dampening agent supply line, with hole-shaped cutouts, and a dampening agent catch rod, which is situated at a defined small distance from the dampening ductor, are positioned parallel to the dampening ductor or roller.  
         [0008]     DE 94 20 343 U1 shows a dampening system, whose dampening agent tank has an inflow line with several openings. A return conduit, having a weir, extends over the entire length of the dampening agent tank.  
         [0009]     DE 199 09 262 A1 describes a dampening agent tank with a dam for limiting the return flow of the dampening agent. A filter has been installed between this dam and a return flow line.  
         [0010]     DE 38 31 741 A1 discloses a dampening agent tank with several inflow lines and with several return flow lines.  
         [0011]     DE 17 61 908 A discloses an adjustable dampening supply device.  
       SUMMARY OF THE INVENTION  
       [0012]     The object of the present invention is directed to providing dampening systems with dampening agent inflow and return flow devices.  
         [0013]     In accordance with the present invention, the object is attained by the provision of a dampening system having at least one dampening fluid ductor or roller, a dampening agent tank, an inflow device and a return flow device. The inflow device has several distributing tubes, each typically with several openings, that are assigned to the ductor. At least one inflow line of the distributing tube is arranged between last openings of first and second ends of the distributing tube. The return flow device has a collecting tank that is connected with the dampening agent tank, which collecting tank extends in the longitudinal direction of the ductor and is double walled.  
         [0014]     The advantages to be gained by the present invention consist, in particular, in that the dampening ductor or roller is arranged in the dampening agent tank between the inflow device and the return flow device for the dampening agent. The inflow device and the return flow device are configured in such a way that the inflow and the return flow of the dampening agent in the area of the dampening ductor are both distributed to several locations. In the course of conducting new or fresh dampening agent from a dampening agent reservoir to the dampening agent tank, uneven intermixing of newly supplied dampening agent with dampening agent already present in the dampening agent tank can occur at some locations in the dampening agent tank. Areas of the dampening agent tank, in which little intermixing takes place, can heat up and can have a temperature which is higher, by up to 10° C., in comparison with areas of the dampening agent tank in which a constant exchange between newly supplied dampening agent with the dampening agent already present in the dampening agent tank takes place. Since the viscosity of the dampening agent depends greatly on the temperature of the dampening agent, and since the print quality, in turn, depends greatly on the viscosity of the dampening agent, the dampening agent taken up from the tank by the dampening ductor must be substantially at the same temperature level over the entire length of the dampening ductor.  
         [0015]     The present invention is directed to the provision of a dampening system wherein a uniform exchange of dampening agent takes place substantially over the entire length of the area of the dampening ductor.  
         [0016]     This objective is achieved in accordance with the present invention because several locations for the inflow of dampening agent, called dampening agent inflow locations, are assigned to the front of the dampening ductor, and several locations for the return of dampening agent, called dampening agent return flow locations, are assigned to the rear of the dampening ductor. Thus, the dampening ductor is located in the area of a flow of dampening agent which is formed by both the inflow and the return flow of the dampening agent into or out of the dampening agent tank. The locations for the inflow and for the return flow are matched to each other in such a way that a uniform intermixing of newly supplied dampening agent with that already present in the dampening agent tank takes place in the area of the dampening ductor and over its entire roller length. In this way, it is possible, for example, to match the spatial arrangement of the inflow and return flow locations among or between each other.  
         [0017]     A further possibility resides in the configuration of the inflow and of the return flow locations themselves, such as, for example, their geometry, shape and/or diameter. It would also be possible to cause uniform intermixing by a suitable distribution of the charging pressure at the dampening agent inflow locations. In actual use, a combination of these various possibilities will result, wherein the actual configuration will have to be determined by empirical tests. In connection with the principle of uniform intermixing of dampening agent, such as water, in the area of the dampening doctor blade over its entire length, it is important that, on the one hand, that dampening agent is supplied at several locations in the area of the dampening ductor and, on the other hand, dampening agent is returned at several locations in the area of the dampening doctor blade in order to assure a continuous exchange of dampening agent in the area of the dampening ductor.  
         [0018]     In accordance with a preferred embodiment of the present invention, the dampening agent inflow device is arranged at the dampening agent tank as a separate component. This is of particular advantage if the inflow device must periodically be disassembled, for example because it has become damaged or dirty. In the present case, it is then possible to remove the inflow device, embodied as a separate component, in a simple and cost-effective manner from the dampening agent tank. Thus, a more cost-intensive disassembly of the entire dampening agent tank is not necessary.  
         [0019]     The dampening agent inflow line is attached substantially at the center of the inflow device. This has the advantage that, following the charging of the inflow line with dampening agent, an almost identical dampening agent pressure prevails at all of the dampening agent inflow locations of the inflow device. In this way, a pressure drop, as is the case when the inflow line is located on one side of the inflow device, is clearly reduced.  
         [0020]     To minimize interference effects of the dampening agent flow in the dampening agent tank, it would be sensible to arrange the tubes of the dampening agent inflow line at the side of the dampening agent tank. At the same time, it is conceivable to use the inflow line as a support for the inflow device. This allows a simple and a cost-effective configuration of the inflow line and the inflow device.  
         [0021]     It is of no importance, for the principle of the invention, in which way the inflow device is configured. It is thus possible, for example, to configure the inflow device as a hollow conductor, such as a round tube, for example.  
         [0022]     To provide dampening agent to the dampening agent tank, uniformly distributed over the entire length of the dampening ductor, it is practical for the dampening agent inflow locations, which are embodied as either circular or rectangular cutouts, to be arranged over the entire length of the hollow conductor and to be evenly spaced apart from each other. A further possibility lies in providing a rectangular cutout for the passage of the dampening agent in the hollow conductor, which rectangular cutout extends substantially over the entire length of the hollow conductor.  
         [0023]     In connection with dampening ductors of great length it is not as possible to provide a uniform pressure at all of the dampening agent inflow locations available, even with a central inflow of the dampening agent into the inflow device, which is embodied as a hollow conductor. In this case, it would be sensible for the inflow device to consist of at least two hollow conductors, which are arranged one behind the other in the longitudinal direction. Each one of these hollow conductors may be separately provided with dampening agent by the use of an inflow line and wherein the two hollow conductors are functionally separated from each other.  
         [0024]     In accordance with a further preferred embodiment, the return flow device consists of at least two cutouts which are arranged in the bottom of the dampening agent tank, and through which the dampening agent can be returned from the dampening agent tank to the dampening agent reservoir. To achieve a uniform removal of the dampening agent from the dampening agent tank it would furthermore be appropriate to arrange the cutouts so that they are parallel with respect to the longitudinal axis of the dampening ductor. A return flow device configured in this way can be accomplished in a particularly simple and cost-effective manner.  
         [0025]     It is particularly advantageous, in accordance with the present invention, if the return flow device has a comb-shaped component which is arranged upstream of the cutouts in the bottom of the dampening agent tank. The comb shape of the component is constituted by alternating areas of tooth-shaped elevations and indentations, wherein a cutout in the bottom of the dampening agent tank is assigned to each indentation area. The comb-shaped component is arranged parallel with respect to the longitudinal axis of the dampening ductor. The comb-shaped component extends over the entire length of the dampening doctor blade, and the tooth-shaped elevations point vertically upward. A type of increase of the cross section of this area is accomplished by the provision of the indentations, because of which increase the dampening agent can preferably flow into the cutouts arranged downstream of the indentations and is removed in this way, from the dampening doctor blade over the entire length of the latter.  
         [0026]     Due to the large temperature difference between the dampening agent and the ambient air it would be prudent to configure the lines for the inflow and for the return flow of the dampening agent into or out of the dampening agent reservoir to be double-walled to achieve some sort of thermal disconnection between the lines conducting dampening agent and the ambient air. Without a thermal disconnection, any moisture contained in the air can condense on the lines charged with dampening agent. Drops of condensate are formed, which drops can settle, for example, in the area of the printing group and/or onto the web of material to be imprinted, which drops can also lead to interference with the printing operation.  
         [0027]     The hollow space of the double-walled inflow and return flow lines is filled with an insulative foam.  
         [0028]     To match the temperature of the new dampening agent supplied from the dampening agent reservoir, in particular in such a way that the dampening agent received on the dampening doctor blade over its entire length has substantially the same temperature, it would be beneficial for a temperature measuring device to be provided in the area of the dampening agent doctor blade in at least two locations. The temperature measuring device can be coupled with a control and/or with a regulating device, by the use of which, the temperature of the supplied dampening agent is regulated. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]     Preferred embodiments of the present invention are represented in the drawings and will be described in what follows.  
         [0030]     Shown are in:  
         [0031]      FIG. 1 , a side elevation view, partly in cross-section, of a preferred embodiment of a dampening system with a dampening agent tank, a dampening ductor and devices for the inflow and return flow of dampening agent in accordance with the present invention, in  
         [0032]      FIG. 2 , a front view, partly in cross-section, of a dampening system in accordance with  FIG. 1  and taken in the sectional direction A shown in  FIG. 1 , and without the comb-shaped component, and in  
         [0033]      FIG. 3 , a front view, partly in cross-section of a dampening system in accordance with  FIG. 1  in the sectional direction B shown in  FIG. 1  and without the dampening ductor. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]     A dampening system in accordance with the present invention, with devices for accomplishing the inflow and the return flow of a dampening agent  01  into or out of a dampening agent tank  02 , is represented in  FIG. 1 . A dampening ductor or roller  03  is attached between an inflow device  04 , as seen in  FIG. 2 , and a return flow device  06 . The inflow device  04  is arranged opposite the front side of the dampening ductor  03 .  
         [0035]     For improved understanding it should be pointed out at this juncture that the inflow device  04  consists of at least one distributing tube  18  with several openings  07 . This is shown most clearly in  FIG. 2 .  
         [0036]     In the present preferred embodiment, the distributing tube  18  is provided as a separate component in the dampening agent tank  02 , as represented in  FIG. 2 , and is preferably substantially located completely below the liquid level of the dampening agent  01 . Moreover, the distributing tube  18  is embodied as a hollow conductor  18  in the form of a round tube  18  and has an interior tube diameter of approximately 10 mm to 20 mm, and in particular has a diameter of 12 mm. A longitudinal axis of the distributing tube  18  extends parallel with a longitudinal axis of the dampening ductor  03 . The length of the distributing tube  18  extends substantially over the length of the dampening ductor  03 .  
         [0037]     As can also be seen by referring to  FIG. 2 , the dampening agent inflow locations  07 , which are embodied as circular cutouts  07 , are arranged over the entire length of the distributing tube  18 . These circular cutouts  07  point or face in a direction toward the dampening ductor  03 . By charging the distributing tube  18  with dampening agent  01 , this dampening agent  01  can then exit through the dampening agent inflow locations  07 , so that dampening agent  01  is supplied to the dampening agent tank  02  substantially over the entire length of the dampening ductor  03 . The distal ends of the distributing tube  18  are each closed, so that no dampening agent  01  can flow out of them. In the present preferred embodiment, the circular cutouts  07  are spaced at equal distances from each other and all have the same diameter. The diameter of each of the circular cutouts  07  lies, for example, within a range of from 1 mm to 5 mm, and is, in particular, 3 mm.  
         [0038]     The cross section or area of each of the circular cutouts  07  corresponds to approximately 25% of the diameter of the round tube  18 .  
         [0039]     The flow path of the dampening agent  01  between the distributing tube  18  and the dampening ductor  03  is identical over the entire length of the dampening ductor  03  because of the parallel orientation of the dampening ductor  03  and the distributing tube  18 . Because the plurality of dampening agent inflow locations  07  are arranged opposite the dampening ductor  03  over substantially its total length, it is possible to supply the dampening agent tank  02  uniformly with dampening agent  01  over substantially the entire length of the dampening ductor  03 .  
         [0040]     The distributing tube  18  is provided with dampening agent  01  from a dampening agent reservoir, which is not specifically represented, through an inflow line  08 . To achieve a substantially uniform pressure of the newly supplied dampening agent  01  arriving at all of the dampening agent inflow locations  07  of the distributing tube  18 , embodied as a round tube  18 , and flowing into the dampening agent tank  02  to mix with the dampening agent  01  already in tank  02  the inflow line  08  is arranged centered along the length of the distributing tube  18 . In contrast to a one-sided inflow of the dampening agent  01  into the distributing tube  18 , with the length of the distributing tube  18  being the same, the dampening agent  01  travels over a substantially shorter flow path before exiting through the dampening agent inflow locations  07 . Moreover, with the inflow line  08  arranged in the center of the distributing tube  18 , and with an identical number of dampening agent inflow locations  07 , only approximately half as many of the dampening agent inflow locations  07  are arranged in series one behind the other in comparison to the orientation that would exist in a one-sided inflow. Because of this configuration, a considerably reduced pressure difference between dampening agent inflow locations  07  spaced far apart from each other, and thereby a substantially identical pressure of the outflowing dampening agent, can be achieved at all dampening agent inflow locations  07 .  
         [0041]     In the present preferred embodiment, the dampening agent inflow line  08  is embodied in the form of a bent round tube  08 , which is either of one piece construction, or which can consist of several components, which are, for example screwed together, welded together or hard-soldered. The connection between the distributing tube  18  and the inflow line  08  can also be provided by a screw connection, a welded connection or a hard-soldered connection. The inflow line  08  at the same time takes on the function of a support for the distributing tube  18 , so that a separate frame for holding the distributing tube  18  in the dampening agent tank  02  can be omitted. In order not to negatively affect the essential function of the dampening system, which could be the case if, for example, the flow of the dampening agent  01  through the tubes of the inflow line  08  were interfered with, the inflow line  08  runs on the side of the dampening agent tank  02  adjacent the bottom of the dampening agent tank  02 .  
         [0042]     In a further preferred embodiment, which is not specifically represented, several distributing tubes  18  can be assigned to the dampening ductor  03 . Each one of these several distributing tubes  18  has its own inflow line  08 .  
         [0043]     At least one inflow line  08  of the distributing tube  18  is arranged between a last opening  07  of a first distal end and a last opening  07  of a second distal end of the distributing tube  18 . The inflow line  08  is, in particular centered along the length of the distributing tube  18 . In the case of several inflow lines  08  for a single distributing tube  18 , these several inflow lines  18  are arranged approximately uniformly distributed in relation to the longitudinal direction of the distributing tube  18 .  
         [0044]     The two last openings  07  of the distal ends of the distributing tube  18  are spaced at a distance IO 1  from each other, as seen in  FIG. 2 . A further distance  102  is defined between the last opening  07  and the inflow line  08 .  
         [0045]     The following relationship applies: IO2= IO1 / N+1′  wherein N is the number of inflow lines  08 , and IO 1  is the spacing between the two last openings of the distributing tube  18 .  
         [0046]     For a distance IO 3  between two inflow lines  08  the following applies: IO3≠ IO1 / N+1′  wherein N is the number of inflow lines  08 , and  101  is the spacing between the two last openings of the distributing tube  18 .  
         [0047]     The openings  07  of the distributing tube  18  are arranged below the surface level of the dampening agent  01  in the dampening agent tank  01 , i.e. within the body of the dampening agent  01 . The inflow lines  08  are also arranged, from the side of the dampening agent tank  02  to the center of the distributing tube  18 , within the dampening agent  01 .  
         [0048]     The inflow line  08  of the distributing tube  18  is arranged, at least in part, in the longitudinal direction of the dampening ductor  03  within the dampening agent. This may be seen most clearly in  FIG. 2 .  
         [0049]     The return flow device  06  has a double-walled collecting tank  16 . Collecting tank  16  is connected with the dampening agent tank  02  and extends in the longitudinal direction of the dampening ductor or roller  03 , as is seen in  FIG. 1 . This longitudinal extension of the collecting tank  16  can also be seen in  FIG. 3 .  
         [0050]     The return flow device  06  is arranged in the dampening agent tank  02  opposite to the rear of the dampening ductor  03 . In the depicted embodiment, the return flow device  06  consists of two components, namely cutouts  09  which are located in the bottom of the dampening agent tank  02  for the return flow of the dampening agent  01  which was carried out of the area of the dampening ductor  03 , and a comb-shaped component  12 , which has been placed upstream of the cutouts  09 . The cutouts  09 , which may be formed as circles, have a diameter of from 10 mm to 30 mm, and in particular of 23 mm. The comb-shaped component  12  is oriented parallel with the longitudinal axis of the dampening ductor  03  and extends over the entire width of the dampening agent tank  02 . In the same way, the downstream located cutouts  09 , formed on the bottom of the dampening agent tank  02 , are also arranged parallel with the longitudinal axis of the dampening ductor  03  and extend substantially over the entire length of the dampening ductor  03 .  
         [0051]     The dampening system, in the area of the return flow device  06 , is represented in  FIG. 3 , in the cross-sectional direction B and without the dampening ductor  03 . The comb-shaped component  12  and the cutouts  09  arranged in the bottom of the dampening agent tank  02  can be seen in this cross-sectional front elevation view. The comb-shaped component  12  is mounted on the bottom of the dampening agent tank  02  and is oriented perpendicularly with respect to it. In the present preferred embodiment, the comb-shaped component  12  is embodied in the form of a comb plate  12  with tooth-shaped elevations  13 . The tooth-shaped elevations  13  each have a linear extension of from 100 mm to 300 mm, in particular of 200 mm. The elevations  13 , in the form of teeth, are formed so that dampening agent return flow locations  14 , which are substantially embodied by incisions  14 , formed in the top of the comb-shaped plate  12 , are open at the top of plate  12  and are extending parallel to each other, and with rectangular and/or triangular and/or curved bottom transitions. The incisions  14 , as well as the alternating tooth-shaped elevations  13 , are located below the liquid level of the dampening agent  01  in the dampening agent tank  02 . The dampening agent  01  coming from the dampening ductor  03  can flow out of the tank  02  over the entire length of the comb-shaped component  12 . However, a sort of a cross-sectional flow volume increase takes place in the area of each incision  14 , because of which flow volume increase, flowing off dampening agent  01  is conducted out of the area of the dampening ductor  03  preferably in the respective areas of the incisions  14 . A separate cut-out  09  in the bottom of the dampening agent tank  02  is assigned downstream of each incision  14  in the comb plate  12 , and through which cut-out  09  the dampening agent  01  is conducted out of the dampening agent tank  02  into a collecting tank  16 . It is assured by this that, in the area of each incision  14 , the dampening agent  01  can flow off unhindered. The dampening agent  01  that flows out of the dampening agent tank  02 , is returned from the collecting tank  16  to the dampening agent reservoir through a return line  11 . The collecting tank  16  extends in the longitudinal direction of the dampening ductor  03 , as seen in  FIG. 3 , and extends, in the transverse direction of the tank  02  and the ductor  03 , at a fraction of the width of the dampening agent tank  02 . The collecting tank  16  has double walls defining a space which is filled with an insulative foam. The incisions  14  in the comb plate  12 , as well as the cutouts  09  in the bottom of the dampening agent tank  02 , are spaced apart from each other at equal distances and extend over the entire length of the dampening ductor  03 . The distance between the tooth-shaped elevations  13  is from 1 mm to 20 mm, and in particular is 5 mm. By the arrangement of the incisions  14  in the comb plate  12  and by the respectively arranged downstream cutouts  09  in the bottom of the dampening agent tank  02 , it is possible to remove dampening agent  01  from the area of the dampening ductor  03  substantially over the entire length of the dampening ductor  03 .  
         [0052]     Analogous to the geometric conditions in the area of the inflow device  04 , the return flow path of the dampening agent  01  between the dampening ductor  03  and the return flow device  06  is also uniform over the entire length of the dampening ductor  03 . This is because of the parallel arrangement of the dampening ductor  03  and the return flow device  06 . Because the dampening agent return flow locations  09 ,  14  are arranged opposite each other, over substantially the entire length of the dampening ductor  03 , dampening agent  01 , coming from the direction of the dampening ductor  03 , can be removed from the area of the dampening ductor  03  uniformly over the entire length of the dampening ductor  03 .  
         [0053]     Since the longitudinal axes of the inflow device  04  and of the return flow device  06  extend substantially parallel with respect to the longitudinal axis of the dampening ductor  03 , and to each other, and because the dampening agent inflow locations  07  are arranged on the front and dampening agent return flow locations  09 ,  14  are arranged on the back of, and substantially opposite the dampening ductor  03 , and extending over the entire length of the dampening ductor  03 , and further because of the substantially uniform charging with pressure of all of dampening agent inflow locations  07 , it is possible, in a simple way, in accordance with the present invention, to supply dampening agent  01  to the dampening ductor  03  over its entire length and to uniformly remove dampening agent  01 . This means that identical flow conditions prevail for both inflowing and oufflowing dampening agent  01  over the entire roller length, so that a uniform intermixing of freshly supplied, inflowing dampening agent  01 , with dampening agent  01  already present in the dampening agent tank  02  can take place over the entire roller length. A uniform exchange of dampening agent  01  is thus assured over the entire roller length. The uniform, equal exchange of dampening agent  01  is additionally aided by setting the direction of rotation  17  of the dampening ductor  03  to be the same as the flow direction of the dampening agent  01 , as seen in  FIG. 1 . Because of the even intermixing of new, inflowing dampening agent with dampening agent  01  already present in the dampening agent tank  02 , the dampening agent  01  picked up by the dampening ductor  03  has identical physical and chemical properties over the entire length of the dampening ductor  03 .  
         [0054]     In place of the cutouts  09  in the bottom of the dampening agent tank  02 , it is also possible to, for example, arrange an additional separating wall, with cutouts  09 , between the dampening agent tank  02  and the collecting tank  16 .  
         [0055]     The size of the inflow and of the return flow at the respective dampening agent inflow locations  07  and at the dampening agent return flow locations  09 ,  14  can be adjusted.  
         [0056]     While preferred embodiments of dampening systems having a dampening agent feeding and return device, in accordance with the present invention, are set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example, a drive source for the ductor, the specific constituency of the dampening fluid, 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.