Abstract:
A reinforced casting assembly formed of ferrous metal for use with hot chamber die casting including a gooseneck, nozzle seat and nozzle. Reinforcing members are used to reinforce the casting. The preferred embodiment is reinforcing the gooseneck as this is where most failures created by the high internal pressure of hot melt die casting occur. The reinforcing members generally are made of steel wire such as a solid or braided wire.

Description:
RELATED APPLICATIONS 
     This patent application is a continuation-in-part of patent application Ser. No. 09/014,182 filed on Jan. 27, 1998, now abandoned. 
    
    
     TECHNICAL FIELD 
     This invention relates to a reinforced casting intended for use in hot chamber die casting processes. 
     BACKGROUND ART 
     Die casting machines generally utilize one of two classifications of casting material pumping systems, either a hot chamber system or a cold chamber system. Hot material chamber die casting machines include parts that are partially submerged in a vat containing the molten metal and thus operate at the temperature of the metal bath. Cold chamber die casting machines are unheated except for the die member which receives the molten metal during the casting process. Hot chamber systems are used primarily for the casting of metals having low melting points such as tin, zinc and lead alloys. Cold chamber machines can be used for die casting most metals, however, they are most commonly used for aluminum, magnesium and copper alloys. 
     The portions of the hot chamber die casting machine that come in contact with the molten metal must have good wear resistance, hardening resistance and softening resistance at the operating temperature of the machine. This is particularly true with the nozzle, nozzle seat and gooseneck sections of hot chamber machines. These components must be able to withstand the continuous washing action of the heated molten metal and maintain their dimensional and structural integrity in spite of the corrosive properties of the molten metal and the extreme temperature and pressure gradients to which they are exposed. The nozzle, nozzle seat and gooseneck of the machine are exposed to injection pressures commonly ranging from 2,000 to 6,000 psi, but can vary with injection pressures sometimes ranging as high as 30,000 psi. Hardening occurs from repeated crystallization and failure results from cracking. 
     The industry has lavished great care in choosing materials for the construction of hot chamber die casting machines. Improved materials for the various parts have led to enhanced resistance against wear, hardening and softening. The industry, however, has had little success in overcoming failure problems resulting from the high operating pressures present in the hot melt die casting process. 
     DISCLOSURE OF INVENTION 
     This invention is generally related to a reinforced casting and specifically related to a reinforced gooseneck and related components for use with a hot chamber die casting machine. The invention provides for the selected reinforcement of the gooseneck, nozzle, and nozzle seat. The preferred embodiment of the invention focuses on reinforcing the gooseneck as this is the location where most pressure-caused failures occur. The reinforcement structure is generally made of steel wire. The wire may be a solid or braided wire. The reinforcements generally have a shape or a combination of shapes. For example, the preferred embodiment is a combination of shapes, one of them being a U-shape with a tail and the other an inverted U-shape. 
     A gooseneck is commonly known to the casting industry as a unit designed to increase the pressure of a molten non-ferrous metal before it is forced or flowed into a die. Goosenecks are most commonly cast from molten grey iron such as cast iron, alloyed cast iron, and semi-steel. They may also be cast from molten steel or alloyed steel. In rare instances, Goosenecks are machined from a block of steel or alloyed steel. 
     Grey iron goosenecks have many advantages when compared to steel goosenecks. Grey iron is generally more stable when subjected to the heat levels found in hot melt die casting processes. The internal channel of the gooseneck cast from grey iron can also be cast, thereby allowing for the creation of a smooth path having gentle curves for the molten non-ferrous metal to flow through to the die. A smoothly flowing molten metal has less turbulence and therefore the final die cast product is denser and has less porosity. The preferred internal channel of a grey iron gooseneck is also preferably cast to have a gradually reducing diameter in the direction of fluid flow. However, a major disadvantage of grey iron goosenecks lies in the low tensile strength of grey iron as compared to steel and resultant failures when the goosenecks are subjected to regular and sustained high pressure levels. 
     Goosenecks cast or machined from steel, on the other hand, have greater strength than grey iron castings. Steel goosenecks, however, have several disadvantages. The internal channel must be machined or drilled, thereby creating sharp angular corners which tend to interfere with the smooth flow of molten metal creating considerable turbulence and frothing of the molten metal. Such turbulence and frothing lowers the pressure of the molten metal entering the die cavity and increases the porosity of the metal flowing into the die cavity. Further, plugs must be installed where the channels were machined or drilled and the plugs create an area of weakened structure in the gooseneck, thus creating an enhanced chance of failure of the gooseneck, as well as additional maintenance. 
     The present invention provides a cast grey iron gooseneck having steel reinforcements fused with the grey iron around the internal channel. The reinforced gooseneck of this invention offers the strength advantages of steel combined with the positive advantages of grey iron goosenecks. The invention provides a high strength gooseneck with a smooth internal channel, preferably having a gradually reduced diameter and having gentle curves, and a good stability when exposed to the extreme heat of the hot melt die casting process. 
     The same principals discussed above are applicable to the nozzle and nozzle seats. Other embodiments envision bimetallic components using an expensive or exotic metal, such as austenitic stainless steel as a core surrounding the internal channel of the gooseneck, nozzle and nozzle seat with the reinforced casting surrounding the exotic metal core. Finally, it is envisioned that other embodiments of the invention will provide reinforced cast steel goosenecks for certain desired applications. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional side elevational view of a die casting machine and die according to the present invention. 
     FIGS. 2A to  7 A are cross-sections of a gooseneck, showing various embodiments of the invention taken along line A-A′ of FIG.  1 . 
     FIGS. 2B to  7 B are core cross-sections of a gooseneck, showing the various embodiments of FIGS. 2A-7A, taken along line B-B′ of FIG.  1 . 
     FIG. 8 is partially an exploded view of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This assembly for use with hot chamber die casting comprises a gooseneck assembly having a channel extending therethrough, wherein the gooseneck assembly is made from a ferrous material having reinforcing members. The gooseneck assembly has an exterior surface, an interior surface and an interior located between the exterior and interior surfaces. The interior surface defines the channel extending therethrough, and the reinforcing members are located in the interior of the gooseneck assembly. Generally, the reinforcing members are centrally located in the interior between the exterior and interior surfaces. Preferably, the reinforcing members are located equidistant in the interior between the exterior and interior surfaces. In one embodiment, the casting includes a transition layer between the interior of the gooseneck assembly and the reinforcing members, wherein the transition layer is a mixture of the interior and the reinforcing members. This transition layer is a fused layer of the mixture. The reinforcing members are fused within the ferrous material provide radially oriented reinforcement within the interior of the gooseneck assembly. 
     FIG. 1 shows a hot chamber die casting machine having a submerged plunger mechanism, a gooseneck and a nozzle. The machine  12  consists of a molten metal reservoir  18 , a plunger  20 , pressure cylinder  22 , gooseneck  24 , nozzle seat  26  and nozzle  10 . The nozzle  10  is designed to matingly engage with a die cavity  28  of a die  16  so that molten metal  14  is received into the die cavity  28  from the machine operation. 
     The gooseneck  24  and pressure cylinder  22  are partially submerged in the reservoir  18  of molten non-ferrous metal  14 . An intake port  30  provides a passageway between the pressure cylinder  22  and the reservoir  18 . With the plunger  20  in the up position (as shown in FIG.  1 ), molten metal  14  is free to flow from the reservoir  18  through the intake port  30  and into the pressure cylinder  22 . When the plunger  20  is moved downward, it passes the intake port  30 , thereby sealing off the pressure cylinder  22  from the reservoir  18 . As the plunger  22  continues to travel downward, it pressurizes the molten metal  14  and forces the molten metal  14  contained in the cylinder  22  through the channel  32  in the gooseneck  24 , through the nozzle seat  26  and the nozzle  10 , into the die cavity  28  of the die  16 , thereby filling the cavity and forming the cast part. 
     After the metal has solidified in the die cavity  28 , the plunger  20  is retracted, thereby uncovering the intake port  30  and molten metal again flows from the reservoir  18  into the pressure cylinder  22 , thus readying the machine  12  for the next cycle. 
     FIGS. 2A and 2B show a preferred embodiment of the reinforcing members  36 ,  38  positioned around the channel  22 . The reinforcing members include a first “U”-shaped member with a tail  38  and an inverted “U”-shaped member  36  positioned in opposed relationship to the first “U”-shaped member. If the reinforcing members  36 ,  38  have differing shapes, they are alternatingly spaced along the length of the internal channel  32 . The gooseneck  24  is most commonly cast in sand molds using a ferrous metal, preferably grey iron or cast iron, and the reinforcing members  36 ,  38  are formed of steel wire fused with the grey iron in the gooseneck during its manufacture by casting. The steel reinforcing members  36 ,  38  provide radially oriented reinforcement within the cast body of the gooseneck and assist the gooseneck casting in withstanding the pressures exerted within the channel  32  by the molten metal. The reinforcing members  36 ,  38  are alternatingly positioned in spaced relationship the full length of the channel  36  along the gooseneck  24 . The preferred material for the reinforcing members  36 ,  38  is 41/40 steel or stainless steel because of the high strength characteristics and stability of 41/40 steel and stainless steel when exposed to the nonferrous molten metal used in the die casting process. 
     Preferably, the reinforcements  36 ,  38  are always positioned in the grey iron to be perpendicular to the longitudinal extension of the internal channel  32 . The reinforcements  36 ,  38  are ideally spaced, in an alternating pattern, a distance of approximately two to three times the cross-sectional thickness of the reinforcement  36 ,  38  from each other. Each reinforcement is also ideally spaced a distance of two to three times it cross-sectional thickness from the internal channel  32 , but no greater a distance than one-half the distance between the internal channel  32  and the exterior surface  33  of the gooseneck  24 . In the preferred embodiment shown in FIGS. 2A and 2B, the surface of the reinforcements are roughened or notched to enhance the anchoring or fusing of the reinforcement in the cast grey iron. 
     Other embodiments of reinforcing the gooseneck are envisioned. For instance: 
     FIGS. 3A and 3B show a pair of straight reinforcing members  40  extending through the gooseneck  24  in opposed and parallel relationship. Straight reinforcing members  40  also are preferred in the more curved portions of gooseneck  24 . Curved and shaped reinforcements are more difficult to position in the curved portions of gooseneck  24  such as the neck area near nozzle seat  26 . 
     FIGS. 4A and 4B show a loop reinforcing member  42  and a straight reinforcing member  44  extending through the gooseneck  24  substantially to surrounding the channel  32 . 
     FIGS. 5A and 5B show an eye-shaped reinforcing member  46  extending into the gooseneck  24  and substantially surrounding the channel  32 . 
     FIGS. 6A and 6B show a circular coil reinforcing member  48  through gooseneck  24  surrounding the channel  32 . 
     FIGS. 7A and 7B show a U-shaped reinforcement  36  through gooseneck  24 . 
     The alternative embodiments of the reinforcing members shown in FIGS. 3A,  3 B to  7 A,  7 B are intended to have the same physical and structural characteristic as those described above in reference to FIGS. 2A and 2B. 
     FIG. 8 is a partially exploded view of FIG. 1 showing the positioning of reinforcing members  36  and  38  in greater detail. FIG. 8 shows exterior surface  50 , interior surface  52 , interior  54  and fused layer  56 . Interior surface  52  defines channel  32  by circumscribing or surrounding it. Exterior surface  50  and interior surface  52  incase interior  54 . Interior  54  houses reinforcing members  36  and  38 . Transition layer (fused layer)  56  surrounds reinforcing members  36  and  38 . 
     Reinforcing members  36  and  38  generally have a structural configuration which can be adapted to fit interior  54 . The structural configuration of reinforcing members  36  and  38  may vary widely. Generally, the structural configuration is continuous or discontinuous. Preferably, it is a wire like member readily conformable to shaping or bending. The reinforcing members may take the form of a web, mat, sheet, cylinder, spiral, cage, grid or the like. Preferably, however, the reinforcing member has a shaped, wire like structural configuration such as those shown in FIGS. 2B to  7 B. 
     Ideally, die casting components should be made out of a metal that is smooth, wear and corrosion resistant, rigid and able to withstand the temperatures and pressures experienced in hot chamber die casting. This is especially true with the nozzle, nozzle seat and gooseneck. Applicant has found success in combining bimetallic components with the reinforcements to form a nozzle  10 , wherein the nozzle  10  has an inner core or layer  11  formed of an exotic or expensive metal and an outer layer  13 , grey iron, which is cast about the inner core  11 . The inner core  11  forms the internal channel  32  which runs longitudinally through the nozzle  10  and carries the molten metal to the die cavity  28 . The inner core must be constructed of a material that is capable of providing a smooth surface that is corrosion and wear resistant to the molten material being pumped through the bore or channel. A preferred inner core is formed of austenitic stainless steel. The outer layer  13  is preferably reinforced in the manner described above with regard to the gooseneck  24 . 
     This type of bi-metal casting is particularly suitable for use as the nozzle  10 . The reinforcing members that are utilized in the gooseneck may be incorporated within the nozzle  10 , whether it be constructed of steel, bimetallic or cast. Bi-metal casting is also suitable for desired applications and for use in constructing the nozzle seat  26  and gooseneck  24 . 
     The term “gooseneck” is not to be constructed as meaning “in the shape of a gooseneck”, but merely an arrangement with a similar function and providing a duct channel or bore for the molten metal to be injected from the cylinder, upwards alongside the cylinder and laterally to a die. 
     The above description of the invention and the alternative embodiments is intended to be illustrative of the invention as a whole and not limiting upon the scope of the following claims. It is envisioned that the reinforcing members may be incorporated into any cast member which is exposed to internal pressures and subject to bursting and failure as a result of the pressures.