Patent Publication Number: US-9427788-B2

Title: Cooling device for a rolling mill work roll

Description:
BACKGROUND 
     1. Field 
     Embodiments of the present invention relate generally to the cooling of work rolls in a rolling mill, and are concerned in particular with improving the cooling efficiency of liquid coolants such as water or the like applied to the roll surfaces. 
     2. Description of Related Art 
     In a known arrangement, as disclosed for example in U.S. Pat. No. 6,385,989 (Cassidy), a coolant delivery device partially surrounds a work roll and serves as a supply manifold for nozzles arranged to apply cooling water to the roll surface. Although such devices operate in a generally satisfactory manner, it has now been determined that their efficiency is compromised by the Leidenfrost effect, a phenomenon in which a liquid, in near contact with a body significantly hotter than the liquid&#39;s boiling point, produces an insulating vapor layer that keeps the liquid from boiling rapidly. The thermal conductivity of the vapor is much poorer than that of the liquid, resulting in reduced cooling efficiency. 
     SUMMARY 
     Broadly stated, embodiments of the present invention are directed to disrupting the Leidenfrost effect, thereby increasing the cooling efficiency of a liquid coolant being applied to a work roll surface. 
     In exemplary embodiments of the present invention, the application of the liquid coolant to a surface area of a work roll is accompanied by the simultaneous application to the same surface area of a pressurized gas. 
     Typically, the liquid coolant is water and the pressurized gas is compressed air. 
     In a preferred embodiment of a cooling device in accordance with the present invention, a manifold housing has a generally concave inner edge configured and dimensioned to surround a surface area of the work roll. The housing includes a first means for applying water or other like liquid coolant to the work roll surface area via first outlets arrayed along the housing inner edge, and second means for simultaneously applying compressed air or other like pressurized gas to the same work roll surface area via second outlets also arrayed along the inner housing edge. 
     Preferably the first nozzles are located in two parallel first planes, and the second nozzles are located in a second plane between and parallel to the first planes. 
     These and other features, objectives and advantages of the present invention will become more apparent upon reading the following detailed description in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of a cooling device in accordance with an exemplary embodiment of the present invention, shown in an operative position adjacent to a rolling mill work roll; 
         FIG. 2  is a perspective view of the cooling device shown in  FIG. 1 ; 
         FIG. 3  is an enlarged view of the circled portion shown in  FIG. 2 ; 
         FIG. 4  is an end view of the cooling device shown in  FIGS. 1 and 2 ; 
         FIGS. 5 and 6  are sectional views taken respectively along lines  5 - 5  and  6 - 6  of  FIG. 4 ; and 
         FIG. 7  is an exploded view of the cooling device shown in  FIGS. 1, 2 and 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The components described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Other suitable components that are capable of performing the same or similar functions as well as the materials described herein are intended to be encompassed within the scope of the present invention. 
     With reference initially to  FIG. 1 , a cooling device in accordance with an exemplary embodiment of the present invention is generally depicted at  10  at a location adjacent to a work roll  12   a . Work roll  12   a  and a companion work roll  12   b  define a roll pass therebetween configured and dimensioned to roll a product “P” moving in the direction diagrammatically indicated by arrow  14 . 
     The cooling device  10  comprises a manifold housing  16  having a generally concave inner edge  18  configured and dimensioned to surround a surface area “A” of the work roll  12   a.    
     With reference additionally to  FIGS. 2-7 , it will be seen that the manifold housing  16  may comprise a modular assembly of exterior first sections  20   a ,  20   b  sandwiching an interior second section  22  therebetween. End blocks  24  or the like may serve as the means for mounting the cooling device to a mill housing or other like support structure (not shown). 
     Networks of first grooves  26  on the interior surfaces of the first housing sections  20   a ,  20   b  comprise a first means for applying a liquid coolant to the work roll surface area A via first outlets  28  arrayed along the inner edge  18  of the manifold housing  16 . 
     With reference to  FIG. 6 , A network of second grooves  30  in a surface of the interior second housing section  22  comprises a second means for applying a pressurized gas to the work roll surface area A via second outlets  32  also arrayed along the inner edge  18  of the manifold housing  16 . 
     As can best be seen in  FIG. 4 , the first outlets  28  are alternately arranged in a staggered relationship in two parallel first planes P 1 , and the second outlets  32  are arranged in a second plane P 2  between and parallel to the first planes P 1 . 
     The network of first grooves  26  on the inner surface of exterior first section  20   b  are closed by an abutting surface of the interior second section  22 . The network of second grooves  30  are closed by an interior cover plate  34 . 
     The network of first grooves  26  on the interior surface of exterior first section  20   a  are closed by an outer abutting surface of the cover plate  34 . 
     The networks of first grooves  26  may be supplied by liquid coolant received via external connections  36 , and the network of second grooves  30  may be similarly supplied with pressurized gas via external connections  38 . 
     In  FIGS. 1, 3 and 5-7 , the application of liquid coolant is diagrammatically depicted by solid arrows, and the application of pressurized gas is similarly diagrammatically depicted by broken arrows. 
     The modular design of the cooling device  10  accommodates disassembly of the constituent sections  20   a ,  20   b ,  22  for periodic cleaning of the groove networks  26 ,  30  and associated outlets  28 ,  32 . The groove networks and outlets are machined into the housing sections, and as such can be tailored to suit specific applications. 
     The cooling device of the present invention can readily be made from many different materials including metal plate, cast metal, plastic, ceramic, or composite materials. Thus, in a rolling mill environment where cooling water can often have entrained abrasive particles, an abrasion resistant material can be used. If the cooling water contains minerals that can adhere to passage walls, a non-stick lining or coating can be applied to interior surfaces. Corrosion-resistant coating may also be employed where appropriate. 
     The geometry of the manifold conduit can also be varied to provide each delivery outlet with near equal pressure thereby further optimizing coolant delivery. 
     Although not shown, it is to be understood that a second cooling device in accordance with the present invention and as described above is employed to cool the companion work roll  12   b.    
     In light of the foregoing, it will now be understood that in accordance with the present invention, the application of a liquid coolant to a surface area of a work roll is simultaneously accompanied by the application of a pressurized gas to the same surface area. The application of pressurized gas serves to disrupt and eliminate or at least significantly reduce the Leidenfrost effect, thereby beneficially enhancing cooling efficiency.