Abstract:
A continuous galvanizing system includes a feed system for providing a continuous supply of material to be galvanized. A furnace receives the material from the feed system for heating the material. A continuous flux line applies liquid flux to the heated material at an exit end of the furnace prior to exposing the material to atmosphere. A zinc furnace galvanizes the heated material.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a galvanizing system and, more particularly, a continuous galvanizing system that applies liquid flux to a heated material prior to galvanizing.  
         BACKGROUND OF THE INVENTION  
         [0002]    Galvanizing is a process used for coating a metal, such as iron or steel, with zinc. The zinc protects the metal from corrosion. A galvanized metal is typically prepared by removing rust using sulfuric acid or the like and then dipping the metal into molten zinc. A layer of the zinc remains on the surface of the metal.  
           [0003]    Continuous galvanizing systems are used for galvanizing metal products such as wire, fencing, sheeting and tubing. One known galvanizing system runs the material through a cleaner, such as a sand furnace, and subsequently through an anneal furnace. Thereafter, the material is submerged in hydrochloric acid and air dried. A galvanizing flux may be used to dissolve any oxides that form on the metal and prevent further oxidation before galvanizing. The material is then run through a galvanizing kettle or zinc furnace, or the like, including a molten bath of zinc. A zinc alloy is formed on the material when the material reaches the temperature of the bath, which is typically on the order of 850° F. The longer the material is submerged, the heavier the coating. With continuous systems it is desirable to run the material through at high speeds. However, due to the time required to elevate temperature of the material, the line speeds may only be on the order of 100 feet per minute. This must be done to ensure that the finished product maintains appropriate ratings and classification for desired uses. For example, a class 1 coating of about 0.28 inches cannot be achieved at higher speeds.  
           [0004]    The present invention is directed to overcoming one or more of the problems discussed above in a novel and simple manner.  
         SUMMARY OF THE INVENTION  
         [0005]    In accordance with the invention, there is provided a continuous galvanizing system which applies liquid flux to a heated material at an exit end of a furnace prior to exposing the material to atmosphere.  
           [0006]    Broadly, a continuous galvanizing system in accordance with the invention includes feed means for providing a continuous supply of material to be galvanized. A furnace receives the material from the feed means for heating the material. Means are provided for applying liquid flux to the heated material at an exit end of the furnace prior to exposing the material to atmosphere. A zinc furnace galvanizes the heated material.  
           [0007]    It is a feature of the invention that the furnace comprises a tube furnace and the material passes through a tube in the furnace. The tube may be filled with hydrogen. The applying means may deliver a continuous supply of the liquid flux at an exit end of the tube. The tube may be tilted downwardly whereby the liquid flux seals the exit end of the tube.  
           [0008]    It is another feature of the invention that the furnace heats the material to a temperature of above 1000° F. and the liquid flux bakes on the material and cools the material to less than a temperature of the zinc furnace.  
           [0009]    There is disclosed in accordance with another aspect of the invention a continuous wire galvanizing system including a feed system for providing a continuous supply of wire between a supply frame and a take-up frame. A tube furnace has a tube receiving the wire from the supply frame for heating the wire. Means are provided for supplying liquid flux at an exit end of the tube to submerge the wire prior to exposing the wire to atmosphere. A zinc furnace galvanizes the heated wire.  
           [0010]    The tube furnace may heat the wire to a temperature of over 1,000° F. and the liquid flux bakes on the wire and cools the wire to a temperature less than a temperature of the zinc furnace. The zinc furnace may have a temperature of about 850° F.  
           [0011]    It is a feature of the invention that the feed system feeds the wire at a speed greater than about 200 feet per minute. The speed may be in the range of about 200-250 feet per minute.  
           [0012]    There is disclosed in accordance with another aspect of the invention a continuous wire galvanizing system comprising a feed system for providing a continuous supply of wire between a supply frame and take-up frame. A first furnace preheats the wire from the supply frame. A second furnace receives the preheated wire for annealing the wire in a hydrogen atmosphere. Means are provided for recirculating liquid flux at an exit end of the second furnace to submerge the wire prior to exposing the wire to ambient atmosphere. A zinc furnace galvanizes the annealed wire.  
           [0013]    Further features and advantages of the invention will be readily apparent from the specification and from the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a schematic view of a continuous wire galvanizing system in accordance with the invention; and  
         [0015]    [0015]FIG. 2 is a detailed side view illustrating the system for applying liquid flux to the heated wire in the galvanizing system of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Referring to the drawings, and particularly initially to FIG. 1, a continuous galvanizing system  10  in accordance with the invention is illustrated. The continuous galvanizing system  10  implements a process for coating a metal, such as iron or steel, with zinc. In the illustrated embodiment of the invention, the continuous galvanizing system  10  comprises a wire galvanizing system. However, the continuous galvanizing system  10  could be used for galvanizing other materials such as, for example, fencing, sheet and tubing material.  
         [0017]    The galvanizing system  10  includes a feed system  12  for providing a continuous supply of wire W between a supply frame  14  and a take-up frame  16 . The supply frame  14  is illustrated schematically as a spool  18  driven in a direction indicated by an arrow. The take-up frame  16  is illustrated schematically by a spool  20  driven in a rotation indicated by an arrow. The spools  18  and  20  are driven by conventional external apparatus (not shown) to feed a wire W therebetween. As will be apparent other any drive system may be used to provide a continuous supply of wire W for the described galvanizing process.  
         [0018]    Particularly, the galvanizing system  10  further comprises a sand furnace  22 , a tube furnace  24 , a flux line  26 , a zinc furnace  28  and a wax line  30 . The wire W from the supply frame spool  18  is initially fed through the sand furnace  22 , upwardly around a first roller  32 , and then over a second roller  34  and subsequently through the tube furnace  24 . The flux line  26  is positioned at an exit end  36  of the tube furnace  24 . The wire W passes from the flux line  26  to the zinc furnace  28 . The wire then passes over a third roller  38 , over the wax line  30  and then is taken up on the take-up frame spool  20 .  
         [0019]    The sand furnace  22  is conventional in nature and may comprise a forty foot long sand furnace including a fluid fire at approximately 1,400° F. Particularly, such a conventional sand furnace  22  may conclude aluminum oxide through which the wire W passes with air underneath to heat the wire to a red hot condition for cleaning the wire W.  
         [0020]    The tube furnace  24  is generally conventional in construction. In the illustrated embodiment of the invention, the tube furnace  24  is approximately sixty feet long and includes twenty four one inch stainless steel tubes. Referring to FIG. 2, a portion of one of the twenty four tubes  40  is illustrated. The tube  40  extends past the furnace exit end  36 , illustrated in phantom in FIG. 2, and is used in the flux line  26 , as described below. The wire W passes through the tube  40 . As a result the continuous galvanizing system  10  can galvanize up to 24 lines of wire simultaneously. Because the process for each line is the same only one is described in detail herein. The tubes are surrounded by hot electrodes (not shown) with a water jacket around the tubes. The tube furnace  24  may be set to a temperature on the order of 1,600° F. In an exemplary embodiment of the invention, the wire W exits the annealing tube furnace at a temperature above 1,000° F.  
         [0021]    The tube  40  is tilted at about a 15° angle to a horizontal plane. The tube  40  has an exit end  42  through which the wire is withdrawn. A first “T”  44  is provided generally proximate the exit end  42  for introducing hydrogen from a hydrogen source  46 . A second “T”  48  is disposed between the first “T”  44  and the exit end  42 . A hose  50  is connected between the second “T”  48  and a pump  52 . The pump  52  has an inlet connected to a vessel  54 . The vessel  54  stores a supply of liquid flux. The liquid flux may be, for example, zinc aluminum chloride and water. Other flux materials can be used. The second “T”  48  acts as a manifold for the liquid flux. The pump  52  pumps the liquid flux via the second “T”  48  into the tube  40  proximate the exit end  42  to submerge the wire W. The flux bakes on the annealed wire. Because of the tilt of the tube  40 , excess liquid flux is always in the tube  40  at the exit end  42  and drains to the vessel  54 . The liquid flux as such makes an airtight seal to keep the hydrogen atmosphere inside the tube  40  so the heated wire is sealed from the ambient atmosphere. The wire W is then exposed to ambient atmosphere after exiting the tube exit end  42  but the wire W is prevented from oxidizing by the baked on flux.  
         [0022]    The zinc furnace  28  comprises about a thirty foot bath of zinc and has a galvanizing bath temperature of about 850° F. The flux line  26  cools the wire approximately 200° so that it is below the 850° F. temperature of the zinc furnace  28 . This allows the wire W to heat back up to the galvanizing bath temperature.  
         [0023]    As described, the flux agent being applied to the heated annealed wire W bakes on very rapidly and provides a brighter, smoother and more consistent wire product. More particularly, in an exemplary embodiment to the invention, the tube furnace  24  heats the wire to about 1,000° and is operated at above 200 feet per minute and, particularly, at a range of about 200-250 feet per minute. Because of the tilt angle of the tube  40  excess liquid flux is always in the tube  40  to seal the tube end  42 . This satisfies two purposes. One, the liquid flux cools the wire a few degrees below the temperature of the zinc furnace  28  which is necessary for good galvanizing and does so at high speed. Additionally, there is no acid bath used anywhere or rinse water that is acid rich.  
         [0024]    Thus, in accordance with the invention, the continuous galvanizing system includes the ability to apply a controlled flux on the wire while operating the system at a high speed.