Patent Publication Number: US-6991186-B2

Title: Spray boom for a hydraulic descaling facility

Description:
The present invention relates to a spray boom of a hydraulic descaling facility with a plurality of spray nozzles arranged on its surface. 
   Scale, which is produced in a furnace during rolling or casting, leads to a high wear of tools or rolls and prevents an early detection of casting errors, which adversely affects the quality of the end product. 
   The scale can be removed chemically, electrochemically or mechanically. An effective mechanical descaling is possible with hydraulic descaling facilities, which remove primary or secondary scale with jets of pressurized water. 
   The pressurized water jet, which strikes the glowing scaled steel surface, removes the scale. Among the process-relevant parameters, a cooling-down effect and fracture effect can be named and the influence of which essentially depends on the flow rate per unit of time, the water pressure in front of the nozzle and the distance between the nozzle and the removable material. The known hydraulic descaling facilities includes spray booms with a plurality of spray nozzle arranged on its surface. 
   DE 3733131 A1 discloses a spray boom in which separate spray valves actuate separate spray nozzles. With such spray booms, the energy and water consumption can be adapted to the width of the descalable rolling stock. 
   DE 198 05 377 A1 discloses, in addition, a spray boom with a plurality of groups of spray nozzles arranged in a row, with the spray nozzles being separately actuated by actuation of a common servo component. The servo component is arbitrary axially displaceable, rotated, or is screwed in or out of a distribution pipe for the spray water. 
   In addition to an exact adaptation to the width, with an ever increasing range of to-be-rolled special steels, a temperature constancy from the strip beginning to the strip end plays a crucial role. Finally, there is a need in rolling processes with which the simultaneous spraying of water is not necessary for each passage of the rolling stock through a stand because otherwise the surface will cooled down too rapidly. 
   Accordingly, on object of the invention is to provide a spray boom which would insure a high temperature constancy from the beginning to the end of the rolling stock and which would prevent a too rapid cooling of its surface. 
   The solution of this problem is based on an idea of an exact turning on and off of the spraying water, in particular, at the strip beginning and the strip end. In addition, exit of the residual water from the spray nozzles should also be prevented. 
   Generally, this object is achieved by assigning a check value to each spray nozzle of a spray boom of the type discussed above. 
   When the spray boom has at least one distribution pipe for feeding water to spray nozzles and feed channels which branch from the distribution pipe to the spray nozzles, the undesirable exit of the residual water is effectively prevented by arranging the check valves in the feed channels, preferably, immediately before each spray nozzle. 
   As soon as a hydraulic control of the descaling facility turns off water, the check valves become effective so that in a blink of an eye, no water reaches the rolling stock. 
   In order to provide for adaptation to the width of the rolling stock, according to a preferred embodiment of the invention, the spray nozzles are actuated separately in per se known manner. 
   Each check valve has, advantageously, a closing spring acting in a direction opposite to the flow direction, so that the check valve opens against a biasing force of the closing spring. The biasing force of the closing spring is adapted to the pressure of water in the spray boom. As soon as the water flow stops, the water pressure is reduced, and the closing springs displace the shut-off elements of the check valves in their closed position. 
   The monitoring and/or the exchange of the check valves is simplified when the check valve is arranged in a block insertable in a feed channel and which is releasably connected with the spray boom. 
   In order to prevent an erroneous operation of the check valve, it is advantageously formed of a corrosion-resistant material. 
   Further advantages and particularities of the invention will become apparent from the following description of an embodiment of the invention. 

   
     The drawings show: 
       FIG. 1  a cross-sectional view of a spray boom according to the present invention; and 
       FIG. 2  a schematic side view of a spray boom according to the present invention; 
   

     FIG. 1  shows a cross-sectional view of a spray boom  1  according to the present invention with a plurality of spray nozzles  2  arranges in a row. The spray boom  1  includes a distributable pipe  3  from which a plurality of feed channels  4 . 1  to  4 . 8  branch to the spray nozzles  2 . 1  to  2 . 8 . The spray nozzles  2 . 1  to  2 . 8  are arranged in a row (see FIG.  2 ). 
   With the distribution pipe  3 , water  4  is fed to the spray nozzles  2 . 1  to  2 . 8  and is sprayed there on the descalable rolling stock  5  that is displaced in a direction shown in  FIG. 1  with arrow  6 . 
   A feed conduit  8  is connected to the connection  7  of the distribution pipe  3  and connects the distribution pipe with a supply  9 ,  11  for high pressure water and low-pressure water. An electrohydraulic control  12  controls feeding into the feed conduit  8 , alternatively, of the high-pressure water with a pressure of about 200 bar and the low-pressure water with a pressure up to 10 bar. 
   Immediately before each spray nozzle  2 . 1  to  2 . 8 , a check valve  13 . 1  to  13 . 8  is arranged. Each of the check valves  13 . 1  to  13 . 8  has a closing spring  16  that acts on a shut-off element  14  in a direction opposite the flow direction  15 , and acts so that the shut-off element  14  immediately closes the feed channel  4 . 1  to  4 . 8  as soon as the electrohydraulic control  12  stops delivery of water from the supply  9 ,  11 . 
   The residual water, which remains in the feed conduit  8  or in the feed channels  4 . 1  to  4 . 8 , is held with the check valve  13 . 1  to  13 . 8 . Because closing springs  16  having different strength are required dependent on whether the descaling facility is operated with the low-pressure or high-pressure water, the check valves  13  are arranged in blocks  17  which are screwed in the spray boom  1 . The blocks  17  have inlets and outlets corresponding to the feed channels  4 . 1  to  4 . 8 , so that the water flows through the check valves which are integrated in the blocks. 
   The control for a spray boom arranged above the strip  5  can be implemented in the same way for a control arranged beneath the strip. 
   LIST OF REFERENCE NUMERALS 
   
       
       No. Designation 
         1 . Spray boom 
         2 . 1 - 2 . 8  Spray nozzles 
         3 . Distribution pipe 
         4 . 1 - 4 . 8  Feed channels 
         5 . Rolling stock 
         6 . Displacement direction 
         7 . Connection 
         8 . Feed conduit 
         9 . High-pressure water supply 
         10 . — 
         11 . Low-pressure water supply 
         12 . Electrohydraulic control 
         13 . 1 - 13 . 8  Check valves 
         14 . Shut-off element 
         15 . Flow direction 
         16 . Closing spring 
         17 . Block