Patent Publication Number: US-2009218375-A1

Title: Close proximity pouring device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     SEQUENCE LISTING OR PROGRAM 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Technical Field of Invention 
     This invention relates generally to an unheated pour box for pouring molten metal into a mold and, more particularly, to such a device equipped with a means to heat the tip of the nozzle during each pour thereby keeping a building up from forming in the nozzle. 
     2. Discussion of Related Art 
     Historically, the pouring of molten metals into molds was done by hand. Because hand pours were not consistent, stopper rod pouring became the preferred method. Herein, molten metal is metered from a pour box and into a mold using a stopper rod and a nozzle. As the stopper rod is raised from it down or closed position, the metal flow rate increases from no flow to its maximum flow rate which is controlled by the height of the metal in the pour box and the diameter of the opening in the nozzle. 
     When stopper rod pouring, the fill rate of a mold is faster at the beginning of the pour than at the end of the pour since the head pressure of the molten metal in the mold decreases as the mold cavity fills. Consequently, the stopper rod must be modulated to slow down the pour rate to prevent over filling a mold. As the stopper rod closes, the last metal to flow from the nozzle tends to freeze, buildup and progressively close down the orifice in the nozzle resulting in erratic pours. 
     Because the pour box is located above the mold, molten metal flows through air before entering the sprue cup in the mold. Not only does this results in oxidation of some of the metal, but air is aspirated into the sprue gassing some metals. 
     Contact pouring was developed by Brunner U.S. Pat. No. 5,465,777 to address the aforementioned problems. Herein, a pressure pour furnace was lowered so that a flat bottom nozzle located in the pour launder would contact a flat surface on the mold. Once the seal was made between the nozzle and mold, the stopper rod was raised and metal flowed into the mold. 
     Contact pouring was also developed by Billau U.S. Pat. No. 6,138,742, wherein molten metal is poured through the orifice of a nozzle that was flush with the bottom of the vessel and the mold. 
     The advantages reported for contact pouring were as follows. First, when the nozzle is seated flush to the mold, air is prevented from entering the mold via the sprue. Second, a significant improvement in the mold fill rate is achieved because the metal head in the pour box provided additional pressure to aid in filling the last portion of the mold. Third, there is no need to modulate the stopper rod opening from beginning to end of pour. Fourth, there is an increase in the casting yield because the weight of the metal associated with the sprue cup was eliminated. Fifth, there is no overfilling of a mold which leaves metal atop the mold. 
     DISADVANTAGES OF THE PRIOR ART 
     The problem with contact pouring is that the nozzle is cooled each time it contacts a mold. Consequently, metal builds up on the nozzle which progressively alters the subsequent pours. To remove the buildup, Brunner U.S. Pat. No. 5,465,777 used a milling cutter to face the bottom of the nozzle. However, the milling cutter could not remove the buildup with the nozzle orifice. Furthermore, the production rate dropped off because the time to face of the nozzle increased the cycle time per mold. 
     OBJECTS AND ADVANTAGES 
     It is an objective of the present invention to overcome the disadvantages of the prior art by providing an improved means to stopper rod pour molten metals into molds while externally heating the nozzle to minimize buildup on the nozzle. 
    
    
     
       DRAWINGS 
       Figures 
       Still other objectives of the present invention will become apparent to those skilled in the art after reading the following specification and by referencing the drawings which: 
         FIG. 1  is a cross section of the Close Proximity Pouring Device in the up position. 
         FIG. 2  is a cross section of the Close Proximity Pouring Device in the down position. 
         FIG. 3  is a cross section of the Close Proximity Pouring Device in the down position pouring a mold. 
         FIG. 4  is a cross section of the Close Proximity Pouring Device in the up position just after pouring a mold. 
     
    
    
     REFERENCE NUMERALS 
     Referring to the drawings, in all of which, like parts are designated by like reference characters. 
       FIG. 1 . typical close proximity pouring device
           110  pour box     111  mold     112  linear actuator     113  stopper rod actuator     114  stopper rod     115  molten metal     116  nozzle     117  truncated conical shape     118  truncated conical pour basin       
       FIG. 2 . typical close proximity pouring device cross section in the down position
           210  fixed stops       
       FIG. 3 . typical close proximity pouring device cross section in the down position with the stopper rod actual raised.
           310  sprue     311  mold cavity       
       FIG. 4 . typical close proximity pouring device cross section in the up position 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description of the preferred embodiment is merely exemplary in nature and is not intended to limit the invention, its application or uses. 
     In  FIG. 1  there is shown a cross section of a close proximity pouring device  100  in the up position. A pour box  110  is held above the mold  111  by means of mechanical devices such as a hydraulic cylinder, a cam or a linear actuator  112 . The pour box  110  is fitted with a stopper rod actuator  113  which raises and lowers a stopper rod  114 . The stopper rod  114  keeps the molten metal  115  in the pour box  110  by means of contact with the nozzle  116 . The bottom of the nozzle  116  has a truncated conical shape  117 . Likewise, the mold  111  has truncated conical shaped pour basin  118 . 
     In  FIG. 2  there is shown a cross section of a close proximity pouring device  100  in the down position. Herein, the pour box  110  has been lowered relative to the mold  111  by means of mechanical devices such as a hydraulic cylinder, a cam or a linear actuators  112  until the pour box  110  sets atop fixed stops  210  so that there is no contact between the nozzle  116  and the mold  111 . 
     In  FIG. 3  there is shown a cross section of a close proximity pouring device  100  in the down position wherein the stopper rod actuator  113  has raised the stopper rod  114  to allow molten metal  115  to flow from the pour box  110  and into the mold  111 . As the molten metal  115  flows into the mold  111 , the down sprue  310  fills with molten metal  115 . Since the rate of metal flow into the sprue  310  is faster than the rate at which the mold cavity  311  will accept the molten metal  115 , the molten metal  115  fills part of the conical gap  117  between the truncated conical shape  117  of the nozzle  116  and the truncated conical pour basis  118  in the mold  111 . The hot metal  115  heats the nozzle  116  during each pour. After three or four pours, the nozzle  116  becomes heated so that the molten metal  115  does not stick to and build up on the nozzle  116 . 
     In  FIG. 4  there is shown a cross section of a close proximity pouring device  100  in the up position just after a pour wherein the stopper rod actuator  113  has closed the stopper rod  114  to stop molten metal  115  flow from the pour box  110  and into the mold  111 . The molten metal  115  that was in the orifice in the nozzle  116  flowed into the truncated conical pour basin  118 . The result is that there are no short or long pours. 
     CONCLUSION 
     The foregoing discussions, disclosures and describes are merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.