Patent Publication Number: US-4318534-A

Title: Plate quench

Description:
BACKGROUND OF THE INVENTION 
     The invention is particularly well suited for use in an apparatus that is designed to quench individual metal plates composed of any suitable material, e.g. aluminum or steel, after the metal plates have passed from a heat treatment furnace. Such quenching apparatuses employ a plurality of rows of metal tire-like wheels or rollers which are driven, in unison, to move and support the hot metal plates as they pass along a fixed horizontal pathway through an enclosed chamber where the hot metal plates are contacted with liquid from a series of nozzles which are located above and below the pathway to direct streams of liquid against the metal plates in a downstream direction relative to the direction in which the metal plates travel. The quantity of the quenching liquid is naturally dependent upon the thickness of the metal plate being quenched. 
     A wake, somewhat similar to that created by a boat, is produced by the rollers as they contact the quenching liquid. These wakes circumvent and isolate tear-shaped areas of the metal plate extending from the leading edges of the rollers, first to contact the liquid, downstream behind the rollers, and prevent adequate liquid from contacting the metal plate in these areas, thereby creating non-uniform quenching of the metal plate during the initial, highly critical stage of the quenching process. Such non-uniform quenching causes the metal plate to buckle and twist making the distorted metal plate exceedingly difficult to handle and, oftentimes, unacceptable from a flatness standpoint. Moreover, the wakes interfer with the rate at which it is necessary to quench the metal plate to produce the metallurgical properties desired in the metal plate. The invention is primarily designed to overcome this problem by the provision and location of nozzles which are positioned to eliminate or substantially reduce the wakes caused by the rollers so that the metal plate when it is hottest at the beginning of the quenching process is uniformly contacted with liquid. 
     Briefly stated, the invention is in a quenching apparatus that comprises a horizontally elongated chamber in which a plurality of transversely oriented rows of parallel metal, tire-like wheels or rollers are located to support an element as it travels along a fixed horizontal pathway through the apparatus. A plurality of nozzles are positioned vertically above and below the pathway to impinge quenching liquid against the element. The nozzles located below the pathway adjacent the opening through which the element enters the apparatus, are positioned between adjacent rows of rollers to impinge streams of liquid to disrupt and substantially eliminate the wakes created by the rollers as large quantities of high velocity quenching liquid contact them. It can be appreciated from above that the term &#34;element&#34;, as used herein, has reference to continuous or discrete plate-like material which has a length and width sufficient for the supporting rollers to create wakes thereagainst, as distinguished from small wire-like material. 
     Another aspect of the invention is in the particular location of the nozzles above the pathway adjacent the entrance opening. Such nozzles are positioned to produce overlapping patterns of liquid at least initially against the element to insure complete coverage of the element with liquid, especially the trailing end of the element which, in the past, has sometimes been alternately cooled and reheated as it passes between spaced streams of liquid from inadequately positioned nozzles. 
     Still another aspect of the invention is in the positioning of nozzles above the pathway adjacent the end of the apparatus from which the element exits to direct streams of liquid in a counterflow direction against liquid flowing atop the traveling element and attempting to escape or exit the apparatus with the element. 
     As previously indicated, large quantities of high velocity liquid are used to quench thicker metal plates providing a horrendous problem of excess liquid disposal, as this large volume of water literally attempts to escape the apparatus with the moving plates. A number of blow-off nozzles are provided to cooperate with the counterflow nozzles adjacent the exit end of the apparatus to direct streams of fluid in lateral directions against the liquid moving atop the traveling plates, to blow such liquid laterally off the opposing longitudinal marginal edges of the plates and help prevent the undesireable exodus of liquid from the apparatus. 
    
    
     DESCRIPTION OF THE DRAWING 
     The following description of the invention will be better understood by having reference to the accompanying drawing, wherein: 
     FIGS. 1-1A is a longitudinal cross-sectional view of a quenching apparatus that is made in accordance with the invention; 
     FIG. 2 is a plan view of the exit end of the apparatus viewed from the line 2--2 of FIGS. 1-1A; 
     FIG. 3 is a transverse section of the apparatus viewed from the line 3--3 of FIGS. 1-1A; and 
     FIG. 4 is a top schematic view designed to illustrate the wakes that are created by the quenching liquid as it contacts the rollers used to support the traveling element. 
    
    
     THE ENVIRONMENT OF THE INVENTION 
     With general reference to the drawing for like parts, and more particular reference to FIGS. 1-1A and 3, there is shown an apparatus 10 which is designed to quench a heated element, such as a plurality of individual aluminum or steel plates 11, after the metal plates 11, for example, leave a heat treatment furnace 12. The quenching apparatus 10 comprises a horizontally elongated housing 13 which encloses a similarly oriented chamber 14 in which the metal plates 11 are contacted by any suitable quenching liquid, e.g. water. The housing 13 has an entrance opening 15 and an exit opening 16 through which the metal plates 11 enter and leave the treatment chamber 14. 
     A plurality of transversely oriented rows of similar, parallel, metal tire-like wheels or rollers 17 are spaced longitudinally of the chamber 14 to support the metal plates 11 in a fixed horizontal pathway between the entrance and exit openings 15, 16, as the metal plates travel through the quenching apparatus 10. The rollers 17 of each row are closely spaced, for example, about twelve inches apart and are driven or rotated, in unison, by any suitable means. 
     A plurality of transversely oriented top and bottom rows of similar, parallel nozzles 18, 19, are spaced longitudinally of the chamber 14 above and below the pathway to impinge streams or jets of quenching liquid against the traveling metal plates 11 in a downstream direction, relative to the direction in which the metal plates 11 travel through the quenching apparatus 10. 
     Those skilled in the art realize that the most critical period of the quenching process occurs in the beginning when the metal plates are the hottest, e.g. heated to a temperature of 900° F.-1000° F. in cases where the metal plates are composed of aluminum. It is important at this time to contact the metal plates 11 uniformly with large quantities of quenching liquid. Thus, the number and location of the nozzles adjacent the entrance opening 15 of the treatment chamber 14 is important and critical to the uniform quenching of the metal plates 11. The nozzles closer the entrance opening are designed to impinge greater volumetric streams of high velocity liquid against the metal plates 11 as they enter the treatment chamber 14, than the nozzles further downstream from the entrance opening 15. It can be appreciated from a study of FIGS. 1-1A, that successive downstream nozzles are sized to impinge succeedingly smaller streams of quenching liquid against the traveling metal plates 11. 
     With particular reference to FIG. 4, there are shown similar wakes 20 which are created beside and downstream behind each of the rollers 17, especially when large quantities of high velocity quenching liquid contact the rollers 17. The wakes 20 produce corresponding, generally tear-shaped areas 21 of metal plates which are not adequately contacted with quenching liquid. Thus, the extremely hot metal plates 11 are not initially uniformly contacted with liquid and quenched, thereby producing uneven thermal contraction of the metal plates 11 and consequent undesireable buckling and twisting of the metal plates 11. Moreover, highly distorted metal plates 11 can experience a cooling and reheating cycle which has a deleterious effect upon the physical characteristics of the finished metal plate 11. Thus, it is desireable to eliminate these wakes 20, especially at the beginning of the quenching process. It has been found that wakes 20 are not a critical factor when, for example, the metal plates being quenched are at temperatures below 400° F. 
     THE INVENTION 
     With particular reference to FIGS. 1-1A and 3, the first eight rows of nozzles 19 located vertically below the pathway of the traveling metal plates 11 adjacent the entrance opening 15, are specifically designed to disrupt or break up the wakes 20 and tear-shaped areas 21 behind the rollers 17 so that the quenching liquid will more uniformly contact the traveling metal plates 11. The first eight rows of nozzles 19 below the pathway each include three rows or series of nozzles 22,23,24 between each pair of adjacent upstream and downstream rows of rollers 17. The first series of nozzles 22 have their discharge openings positioned close to the pathway adjacent the downstream rows of rollers 17 to direct angular relatively high velocity streams of liquid downstream against the undersides of the metal plates 11 just in front of and aside the rollers 17 of the downstream row of rollers 17 to disrupt and substantially reduce and restrict the wakes to a smaller area immediately behind the rollers 17 (note smaller dotted wake areas of FIG. 4 for comparison). The longitudinal axes of this first series of nozzles 22 are preferably disposed at angles less than 45° to the plane of the pathway, e.g. 10°-20°. A second series of nozzles 23 have their discharge openings even closer the pathway adjacent the upstream rollers 17 to direct relatively low velocity streams of quenching liquid in an upstream direction into the reduced wake areas directly behind the rollers 17. The third series of nozzles 24 have their discharge openings positioned farthest from the pathway adjacent the upstream rows of rollers 17 to direct relatively high velocity streams of quenching liquid generally vertically upwardly against the undersides of the traveling metal plates between the adjacent rows of rollers 17 to insure that a sufficient amount of quenching liquid contacts the metal plates 11. The longitudinal axes of the third series of nozzles 24 are preferably disposed at angles greater than 45° to the plane of the pathway of the traveling metal plates 11, e.g. 55°-65°. Thus, the three series of nozzles 22,23,24, located below the pathway between adjacent rows of rollers 17, are designed to eliminate the wakes created by the rollers at least during the first 15-20 feet of the quenching process, where such wakes critically interfere with the uniform quenching of the traveling metal plates 11, and insure that proper amounts of quenching liquid contact the metal plates 11. 
     The first top and bottom rows of nozzles 18,19, to encounter the metal plates 11 as they enter the entrance opening 15, are angularly adjustable so that the streams of liquid from the nozzles thereof can be directed to contact the same longitudinal points of the metal plates 11 to prevent cupping or bowing of the metal plates covered when the top and bottom sides of the metal plates are not simultaneously contacted with quenching liquid at the same longitudinal position. The first four, top rows of nozzles 18 are positioned to direct overlapping streams or patterns of quenching liquid against the traveling metal plates 11 in a downstream direction as the metal plates 11 enter the chamber 14 to insure complete coverage of the trailing ends of the metal plates 11 so that they will not experience alternate cooling and reheating as they pass through the quenching apparatus. This problem occurs in existing devices wherein the sprays or nozzles are simply not designed to produce overlapping streams or patterns of liquid, so that the trailing ends of the metal plates, are intermittently contacted with quenching liquid as they pass between improperly spaced, non-overlapping patterns of liquid that are sprayed or impinged against the traveling metal plates 11 as they enter the treatment chamber 14. 
     With particular reference to FIGS. 1-1A and 2, there is shown another aspect of the invention which is in the provision adjacent the exit opening 6 of a plurality of transversely oriented rows of similar nozzles 25,26 which are located vertically above the pathway and designed to impinge high velocity streams of liquid against the traveling metal plates 11 in a counterflow upstream direction to break up the massive flow of spent quenching liquid that is flowing and carried atop the metal plates 11, as they pass from the quenching apparatus 10, and stop the escape of quenching liquid through the exit opening 16. The rows of counterflow nozzles 25,26 can be straight and at right angles to the traveling metal plates 11, or chevron-shaped, as shown. The chevron-shaped nozzles 25,26 are designed to force the excess liquid laterally over the longitudinal marginal edges of the metal plates 11. 
     A plurality of longitudinally extending rows of similar blow-off nozzles 27-30 are provided upstream adjacent the counterflow nozzles 25,26 to blow fluid transversely or laterally against the moving stream of spent quenching liquid atop the moving metal plates 11, to force such liquid over the adjacent longitudinal marginal edges of the metal plates 11. Thus, between the counterflow nozzles and the blow-off nozzles, sufficient force is provided to stop the mass exodus of quenching liquid from the quenching apparatus 10. 
     Thus, there has been described a quenching apparatus which produces highly improved quenched metal plates. Further, there is described an apparatus in which the massive amounts of quenching liquid used in the quenching process, are confined to the apparatus and prevented from accompanying the metal plates as they exit the apparatus. The nozzles may be of conventional design, since it is the positioning of the nozzle which is important in, (I) the elimination of the wakes created by the rollers, (II) the elimination of unquenched hot spots occurring especially at the trailing end of a metal plate which can cause undesireable cooling and reheating of the metal plates, and (III) the removal of excess quenching liquid attempting to escape from the quenching apparatus atop the metal plate.