Abstract:
This invention relates to a casting machine furnace apparatus including a casting machine furnace, a supply furnace in fluid communication with the machine furnace and operative to supply a molten metal to the machine furnace, and a stopper module device disposed in a fluid path between the casting machine furnace and the supply furnace. The stopper module device includes a block housing and a stopper assembly. The block housing includes an inlet opening and an outlet opening, and is disposed in the fluid path. The stopper assembly is supported for movement relative to the inlet opening of the block housing between a working position, wherein the molten metal flows from the supply furnace to the casting machine furnace, and a non-working position, wherein the flow of molten metal is prevented.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to a casting machine furnace apparatus and in particular to an improved stopper module device for use with such a casting machine furnace apparatus. 
     Pressure pouring of molten metal from a casting machine furnace to fill a mold cavity has been used for several decades. At room temperature, the metals are solid and become fluid when melted with sufficient heat. It is known to use a low pressure countergravity casting apparatus to cast molten metal into a mold. One example of such an apparatus is described in U.S. Pat. No. 5,215,141. Basically, in a low pressure countergravity casting apparatus, molten metal is supplied to a casting apparatus by a machine furnace under pressure. The molten metal is first received into a crucible of the machine furnace. The molten metal in the crucible is then transported to a mold through a feed tube. One problem in managing the molten metal has been optimally replenishing the machine furnace with molten metal. Thus, it would be desirable to develop an apparatus to be used in the replenishing of the machine furnace with molten metal and method for the same which is simple and reliable. 
     SUMMARY OF THE INVENTION 
     This invention relates to a casting machine furnace apparatus including a casting machine furnace, a supply furnace in fluid communication with the machine furnace and operative to supply a molten metal to the machine furnace, and a stopper module device disposed in a fluid path between the casting machine furnace and the supply furnace. The stopper module device includes a block housing and a stopper assembly. The block housing includes an inlet opening and an outlet opening, and is disposed in the fluid path. The stopper assembly is supported for movement relative to the inlet opening of the block housing between a working position, wherein the molten metal flows from the supply furnace to the casting machine furnace, and a non-working position, wherein the flow of molten metal is prevented. 
    
    
     Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial sectional elevation view of a casting machine furnace apparatus according to the invention. 
     FIG. 2 is a sectional view of a portion of the casting machine furnace apparatus illustrated in FIG. 1, showing a stopper module device of the system, the stopper module device being shown in a closed position. 
     FIG. 3 is sectional view similar to FIG. 2 with the stopper module device being show in a raised position. 
     FIG. 4 is a top plan view of a portion of the stopper module device taken along line  4 — 4  of FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, FIG. 1 illustrates a casting machine furnace apparatus, indicated generally at  10 , in accordance with the present invention. As shown therein, the illustrated casting machine furnace apparatus  10  includes a casting machine furnace  12  in fluid communication with a supply furnace  16  which supplies the casting machine furnace  12  with molten metal  15  through a passageway  14 . The passageway  14  may include one or more suitable heating coils  17  proximate thereto, which are operative to generally prevent the molten metal  15  from cooling excessively as it passes through the passageway  14 . The molten metal  15  is supplied to the supply furnace  16  by a holding furnace  20 . 
     The machine furnace  12  preferably supplies the molten metal  15  to a casting apparatus (partially shown at  12 A) thereof through a stalk tube  21  to produce a molded part (not shown); however, the machine furnace  12  can supply the molten metal  15  to any other suitable device or location. An example of a casting apparatus  12 A which can be supplied with the molten metal  15  is disclosed in U.S. Pat. No. 5,215,141 to Kuhn et al., the disclosure of which is incorporated herein by reference. Thus, it can be seen that in the illustrated embodiment, the molten metal  15  generally flows in a “downstream” direction from the holding furnace  20  through the supply furnace  16  to the casting machine furnace  12  and to the casting apparatus  12 A. 
     The illustrated casting machine furnace  12  includes a crucible  22  having an outer wall  24  covered by an intermediate insulation layer  28 . The insulation layer  28  is preferably made of a material that does not transfer heat well. The insulation layer  28  is covered by and supports an inner liner  32 . The inner liner  32  is preferably made of a material that does transfer heat well. Preferably, the inner liner  32  is made of a silicon carbide material. Alternatively, the inner liner  32  can be made from other suitable materials. 
     The casting machine furnace  12  further includes a cover  36  made of a suitable type of material, preferably an insulating type of material. The casting machine furnace  12  is provided with a fluid inlet  40  to allow a suitable fluid  42  to be selectively added to the casting machine furnace  12 . The fluid inlet  40  can be provided in the cover  36  as shown, or can be provided in the cover  36  at any suitable location. Preferably, the fluid  42  is a gas that does not interfere with the physical or chemical properties of the molten metal  15  in the casting machine furnace apparatus  10 . A suitable fluid  42  which can be used is nitrogen gas. In FIG. 1, a dotted line A is provided and is used to illustrate the associated levels of the molten metal  15  and the gas  42  in the casting machine furnace  12 . 
     The illustrated casting machine furnace  12  preferably includes one or more heating elements  44  (two of such heating elements  44  being illustrated in FIG.  1 ). As shown in FIG. 1, at least a portion of each of the heating elements  44  preferably extends into the molten metal  15  in the casting machine furnace  12 . 
     The holding furnace  20  is a suitably shaped vessel designed to hold the molten metal  15 . The illustrated holding furnace  20  includes a pump  48 . The pump  48  is provided to pump the molten metal  15  from the holding furnace  20  to the supply furnace  16 . Any suitable pump  48  can be used for this purpose. One pump  48  which can be used is a Lindberg Varco 100 pump, manufactured by Lindberg/MPH of Riverside, Mich. The pump  48  is operative to move the molten metal  15  from the holding furnace  20  to the supply furnace  16  through a conduit  52 . 
     The illustrated conduit  52  is a generally L-shaped pipe and includes a first generally vertical portion  56  in fluid communication with a second downwardly extending portion  60 . Preferably, the conduit  52  is a ceramic lined discharge elbow and is available from Lindberg/MPH of Riverside, Mich. The downwardly extending portion  60  is operatively joined to a tube  62 . Preferably, the tube  62  is a silicon carbide ceramic tube. Alternatively, the tube can be made from other suitable materials. 
     The conduit  52  includes a fluid inlet  64  provided therein to allow a suitable fluid  68  to be added to the conduit  52 . Preferably, the fluid  68  is a gas that does not interfere with the physical or chemical properties of the molten metal  15 . A suitable fluid which can be used is nitrogen gas. 
     The illustrated supply furnace  16  includes the outer wall  24  covered by the intermediate insulation layer  28 . The insulation layer  28  is covered by and supports the inner liner  32 . The tube  62  extends through the outer wall  24 , the insulation layer  28 , and the inner liner  32  of the supply furnace  16  to allow the molten metal  15  to be supplied from the holding furnace  20  to the supply furnace  16 . In FIG. 1, a dotted line B is provided and is used to illustrate the associated levels of the molten metal  15  and the gas  42  in the supply furnace  16 . The illustrated supply furnace  16  further includes a cover  72  made of a suitable type of material, preferably an insulating type of material. In the preferred embodiment, the casting machine furnace  12  and the supply furnace  16  include common components, namely the outer wall  24 , the insulation layer  28 , and the inner liner  32 . Alternatively, the construction of the casting machine furnace  12  and the supply furnace  16  can be other than illustrated if so desired. 
     The inner liner  32  of the supply furnace  16  is operative to define a receptacle  76 . The receptacle  76  includes a first or upper opening  80  and a second or lower opening  84 . The top opening  80  is defined by a side wall  94  of the receptacle  76 . The bottom opening  84  is formed in an end wall  98  of the receptacle  76 . The top opening  80  is covered by the cover  72 . The supply furnace  16  includes a stopper moving device  86  for a purpose described herein. 
     Referring now to FIG. 2, the lower end  98  of the receptacle  76  includes a stopper seating block housing  102 . The illustrated stopper seating block housing  102  includes a first contact surface  106 , a bottom surface  110 , a second contact surface  118 , a raised surface  126 , a downwardly sloping transition surface  130 , and a third contact surface  140 . The first contact surface  106  is oriented at an angle  114  relative to the bottom surface  110 , and the second contact surface  118  is oriented at an angle  122  relative to bottom surface  110 . Preferably, in the illustrated embodiment, the third contact surface  140  and the second contact surface  118  are aligned along an axis A. The second contact surface  118 , the raised surface  126 , and the transition surface  130  form a protrusion  134  located above the bottom surface  110 . A notch  138  is formed in the stopper seating block housing  102  by the first contact surface  106 , the bottom surface  110 , and the second contact surface  118 . 
     The supply furnace  16  includes a stopper seating block  144 . The stopper seating block  144  is preferably removable to facilitate maintenance and cleaning of the supply furnace  16 . The stopper seating block  144  is preferably made of a material that does transfer heat well. The illustrated stopper seating block  144  includes a first orifice  148  and a second orifice  152 . The first orifice  148  is formed in an upper end portion  154  of the stopper seating block  144 . The upper end portion  154  of the stopper seating block  144  is located above the end wall  98  of the receptacle  76  to define a receptacle  156 . The receptacle  156  is operative to receive or collect sludge  160  or other heavy impurities from the molten metal  15  in the supply furnace  16 . 
     The upper end portion  154  defines a stopper module seat surface  166 . The illustrated stopper module seat surface  166  is defined by a generally inwardly curved or rounded surface. The stopper seating block  144  defines a fluid chamber  168  in fluid communication with the first orifice  148  and the passageway  14  via the second orifice  152 . 
     The stopper seating block  144  seats in the stopper seating block housing  102 . In this position, a lower end surface  164  of the stopper seating block  144  is preferably slightly spaced from contact with the bottom surface  110  of the stopper seating block housing  102 . Also, a tapered side wall  167  of the stopper seating block  144  contacts the first contact surface  106 , the second contact surface  118 , and the third contact surface  140  of the stopper seating block housing  102 . The notch  138  and the protrusion  134  cooperate to support the lower portion  164  of the stopper seating block  144 . 
     The casting machine furnace apparatus  10  further includes a stopper module, indicated generally at  170 . In FIGS. 1 and 2, the stopper module  170  is shown in a closed or seated position in the stopper seating block  144 . In FIG. 3, the stopper module  170  is shown in a raised or unseated position in the stopper seating block  144 . The stopper module  170  includes a stopper housing  174  and a stopper  178 . The illustrated stopper housing  174  includes four inlet or feed orifices  182 , shown in FIG.  4 . The orifices  182  are preferably equally spaced circumferentially around the stopper housing  174 . The illustrated stopper housing  174  further includes four shoulders or protuberances  186 . The illustrated shoulders  186  are located at a lower end  190  of the stopper housing  174  and extend generally radially inwardly relative thereto. As shown in FIG. 4, the shoulders  186  are slightly spaced apart from contact with the stopper  178 . The illustrated stopper  178  is generally rod-like cylindrical structure and defines a longitudinal axis B. As will be discussed, the stopper  178  is movable relative to the stopper housing  174  along the axis B by the stopper moving device  86 . 
     The stopper housing  174  further includes an inner surface  194  and an outer surface  198 . The stopper housing  174  includes a lower curved or rounded outer end surface  197  having an outer surface profile which generally corresponds to the surface of the stopper module seat  166 . The stopper housing  174  includes a lower curved or rounded inner surface  199  having an inner surface profile which generally corresponds to the outer surface profile of a tip  204  of the stopper  178  adjacent a lower orifice  202  of the stopper housing  174 . Thus, it can be seen that when the stopper  178  is in the lowered position shown in FIGS. 1 and 2, it substantially prevents molten metal  15  from flowing from the supply furnace  16  to the passageway  14  and the machine furnace  12 . 
     As shown in FIG. 3, the illustrated shoulders  186  of the stopper housing  174  define a height H 1 . The stopper housing  174  also includes a seat surface  208  proximate the lower orifice  202 . In the illustrated embodiment, the seat surface  208  of the stopper housing  174  is preferably rounded and the height H 1  is defined from about an upper ledge  212  of the shoulder  186  to about the valve seat  208 . It will be appreciated that in FIG. 3 the tip  204  of the stopper  178  is spaced apart from the seat surface  208 . In the illustrated embodiment of the stopper module  170 , the tip  204  of the stopper  178  is preferably not movable above the upper ledge  212  of the shoulders  186 . Thus, the tip  204  of the stopper  178  is not movable along the axis B by a distance of more than the height H 1 . 
     The stopper  178  in the raised position of FIG. 3 is operative to allow the molten metal  15  to flow from the supply furnace  16  to the chamber  168 . To accomplish this, the molten metal  15  flows through the feed orifices  182  of the stopper housing  174 , past the shoulders  186 , through the lower orifice  202  of the stopper housing  174  (as indicated by the arrows  216 ), and through the orifice  148  into the chamber  168  (as indicated by the arrow  220 ). From the chamber  168 , the molten metal  15  flows into the passageway  14  (as indicated by the arrow  224 ). 
     The stopper module  170  in the supply furnace  16  provides for a more desirable use of the casting machine furnace apparatus  10 . It will be appreciated that when the stopper  178  is in the lowered position, the machine furnace  12  can be pressurized. The machine furnace  12  is pressurized by the addition of the fluid  42  through the fluid inlet  40 . The added fluid  42  allows the molten metal  15  in the machine furnace  12  to travel through the stalk tube  22  to the casting apparatus  12 A. The addition of the fluid  68  through the fluid inlet  64  allows the supply furnace  16  to be pressurized. Pressurization of the supply furnace  16  is desirable in that the pressure in the machine furnace  12  is better maintained when the supply furnace  16  is pressurized and the stopper  178  is raised. When the pressure in the machine furnace  12  and the pressure in the supply furnace  16  are similar, the pressure in the machine furnace  12  is not as likely to fluctuate. Fluctuations in the pressure in the machine furnace  12  can lead to problems in the resultant molded part which is produced by the casting apparatus  12 A. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that the invention may be practiced otherwise than as specifically explained and illustrated without departing from the scope or spirit of the attached claims.