Abstract:
An apparatus and method in accordance with the invention for accommodating multiple web widths by controlling fluid flow from a spray bar. Specifically, the apparatus and method receives a request for a reduced web width and controls one or more outside spray nozzles of the spray bar to spray at a reduced flow rate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to IMPROVED SPRAY PATTERN VALVE BODY, U.S. application Ser. No. [to be assigned, attorney docket no. 6003.1025] and CENTRAL MANIFOLD SUPPLY FOR SPRAY BAR, U.S. application Ser. No. [to be assigned, attorney docket no. 6003.1024], the entire disclosures of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to printing presses and more particularly to a spray bar and method for operating the same.  
       BACKGROUND  
       [0003]     Spray bars having multiple spray heads are used in the printing industry to deliver a fluid, such as a fountain solution to a dampener roll which transmits the solution to the plate via several other dampener rolls. A typical spray bar is designed to accommodate the width of a web. If it is desired to run a reduced web width, shutters are attached to the spray bar. Shutters work by truncating the spray pattern of the two spray heads at either end of the spray bar. Typical shutters have multiple settings so the spray bar can run a number of reduced web widths.  
         [0004]     Early shutter designs consisted of a solid blade which did not allow any fluid to reach the ends of the target roll in the truncated region of the spray pattern. This caused premature failure of the roll due to excessive heat generation in the non-wetted area. Another problem with using shutters is that below a certain web length the shutters become ineffective. The effectiveness of shutters is subject to a limited web width range. The use of shutters results in increased waste since a portion of the truncated spray pattern is directed into the drain pan instead of onto the roll.  
         [0005]     More recent shutter designs have been perforated in order to allow a portion of the spray pattern in the truncated region to pass through the shutter to the target roll. This wets the roll enough to prevent premature damage to the roll. Multiple pairs of shutters are sometimes provided to accommodate a greater web width variation.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with an embodiment of the present invention, a spray bar control apparatus and method is provided which accommodate multiple web widths. The apparatus and method receives a request for a reduced web width and controls one or more outside spray nozzles of the spray bar to spray at a reduced flow rate. In this regard, the rate is referred to as a “reduced flow rate” because it is a lower flow rate than the flow rate used when there is not a reduced web width request.  
         [0007]     In accordance with another embodiment of the present invention, a printing unit is provided. The printing unit includes a plurality of spray nozzles arranged axially across a dampener roll to spray a fluid on to a printing plate on the plate cylinder of the printing unit. An interface is provided for communicating with the spray bar, and a processor connected to the interface. The processor is responsive to a request for a reduced web width value, the processor controlling one or more outside spray nozzles of the plurality of spray nozzles to spray at a reduced rate.  
         [0008]     Methods for controlling fluid flow from the plurality of spray nozzles described above are also provided.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Further features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0010]      FIG. 1  illustrates a spray bar in accordance with an embodiment of the present invention;  
         [0011]      FIG. 2  illustrates a controller in accordance with an embodiment of the present invention; and  
         [0012]      FIG. 3  is a flow chart illustrating a process for controlling reduced web widths of the spray bar in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]      FIG. 1  illustrates a spray bar  110  and spray pattern  120  in accordance with an embodiment of the present invention which truncates a spray pattern generated from spray nozzles of the spray bar. As shown in  FIG. 1 , spray bar  110  includes spray nozzles  130 - 1  through  130 - n  and spray patterns  140 - 1  through  140 - n , where n is a predetermined number greater than 1. Not shown in  FIG. 1 , for ease of illustration, is a solenoid in each spray head associated with each spray nozzle for controlling the delivery of fluid through spray nozzles  130 - 1  through  130 - n.    
         [0014]     In the illustrated embodiment of  FIG. 1 , n equals 4. Thus, spray bar  110  has 4 spray nozzles  130 - 1  through  130 - 4  and 4 spray patterns  140 - 1  through  140 - 4 . Spray bar  110  is connected to a fluid source and source line (both not shown). The fluid can be for example a solution, such as a fountain solution used in a dampening system in a printing unit of a printing press which flows from the source and through the source line and spray bar  110 . After entering spray bar  110 , the fluid enters and exits spray nozzles  130 - 1  through  130 - 4  onto, for example, a dampener roll which transmits the fluid to one or more further dampener rolls (collectively, dampener roll arrangement  180 ) which in turn transmits fluid onto a printing plate(s)  170  of a plate cylinder  160 . For example, as illustrated schematically in  FIG. 1 , the spray nozzles  130  are arranged axially across a plate cylinder  160  to spray a fluid on to a printing plate  170  on the plate cylinder  160  of a printing unit via the axially extending dampener rolls of the dampener roll assembly  180 . Although a single spray bar and plate cylinder is described herein, it should be appreciated that a printing unit may include a plurality of plate cylinders, each having a respective spray bar.  
         [0015]     The spray nozzles may be controlled, for example, via solenoids, and the flow rate can be increased or decreased by respectively increasing or decreasing the solenoid frequency or pulse width (on-time). Preferably, the solenoids form part of a solenoid valve in spray nozzle.  
         [0016]     Also shown in  FIG. 1  is spray pattern  120 . Spray pattern  120  shows a first, full web width  145  and a second, reduced web width  150 . Web width  145  is the result of fluid flowing through spray nozzles  130 - 1  through  130 - 4 . Reduced web width  150  is the result of fluid flowing through spray nozzles  130 - 1  through  130 - 4  in accordance with an embodiment of the present invention.  
         [0017]     In accordance with embodiments of the present invention, a printing press automatically adjusts the spray bar(s) for a reduced web width. Referring to  FIG. 2 , a controller  200  includes processor  210  of conventional design, which is connected to memory  215  and interface  205 . In accordance with the invention processor  210  receives, from a user interface, a request for a particular reduced web width  150 , via interface  205  and communications bus  220 . Also received by processor  210  is a value representing the full web width  145 . Such requests are processed by processor  210  in accordance with a program stored in memory  215  which is described below. In response to such request, processor  210  causes outside spray nozzles  130 - 1  and  130 - 4  of spray bar  110  to spray at a reduced flow rate for reduced web width  150 .  
         [0018]     Instructed by the program, processor  210  reads the received request for the reduced web width, as indicated by block  310  in  FIG. 3 . At block  315 , processor  210  determines a percentage web width reduction based on the full web width and the requested reduced web width, where % Web Width Reduction is denoted as X. In short,  
       X   =       %   ⁢           ⁢   Web   ⁢           ⁢   Width   ⁢             ⁢             ⁢   Reduction     =       (             Reduced   ⁢             ⁢             ⁢   Web   ⁢             ⁢             ⁢   Width     -               Full   ⁢             ⁢             ⁢   Web   ⁢           ⁢   Width           )       Full   ⁢             ⁢             ⁢   Web   ⁢           ⁢   Width             
 
         [0019]     At block  320 , processor  210  determines a reduced flow rate for the outer spray nozzles  130 - 1  and  130 - n . The reduced flow rate is determined using the following equation: 
 
Flow Rate(Nozzle #)= q (1− X /2), where 
        #=Spray Nozzle Position, and     q=Flow Rate Per Nozzle For Full Web Width.        
 
         [0022]     As mentioned above, processor  210  determines the reduced flow rate for spray nozzles  130 - 1  and  130 - n , shown below: 
 
Flow Rate(Nozzle 1)= q (1− X/ 2). 
 
Flow Rate(Nozzle  n )= q (1− X/ 2). 
 
         [0023]     The interior Nozzles (Nozzles  2 -( n −1)) are maintained at the flow rate used for the full web width: 
 
Flow Rate(Nozzle 2, 3 . . . ( n −1))= q , where 
        n=Number Of Nozzles Across Spray Bar        
 
         [0025]     Because n=4 in this illustration (i.e. spray heads  130 - 1  through  130 - 4 ), there are 2 spray heads (inside spray heads) that are maintained at a flow rate for the full web width as indicated below: 
 
Flow Rate(Nozzle 2, 3)= q  
 
 and the spray heads maintained at the reduced flow rate are: 
 
Flow Rate(Nozzle 1, 4)= q (1− X/ 2) 
 
         [0026]     At block  330 , processor  210  sends a control signal to the solenoids of spray nozzles  130 - 1  and  130 - 4  to proportionally reduce the flow rate by decreasing solenoid frequency, while maintaining the full web width flow rates of spray nozzles  130 - 2  and  130 - 3 , thus producing the reduced web width  150 , as illustrated in  FIG. 1 .  
         [0027]     The foregoing merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise numerous other arrangements which embody the principles of the invention and are thus within its sprit and scope.  
         [0028]     For example, based on the above disclosure, it is apparent that the principles of the invention can readily accommodate more or less spray nozzles to achieve the benefits of the invention.  
         [0029]     Finally, the system and method are disclosed above in a form in which various functions are performed by discrete functional blocks. However, any one or more of these functions could equally well be embodied in an arrangement in which the functions of any one or more of those blocks or indeed, all of the functions thereof, are realized, for example, by one or more appropriately programmed processors such as digital signal processors (DSPs), microcontroller, microprocessor or system on a chip. Thus, for example, controller  200  may be realized by one or more DSPs, microcontrollers, microprocessors or system on a chip and/or a combination of digital logic devices and other components running a software program or having functions programmed in firmware.