Multiple casting apparatus and method

Abstract

An apparatus and method for pressure casting a battery part wherein an extendible piston includes sidewalls for shutting off the supply of molten lead and an impact surface that extends in a side-to-side condition to form an end surface of a battery part cavity so that when the extendible piston is brought into an intensifying condition the extendible piston shuts off further supply of molten metal while a heat source maintains the lead in a molten state as the impact surface of the piston forms a side-to-side mold cavity surface to complete the mold cavity surface thereby eliminating unevenness in the surface of the finished battery part by generating a force with the extendible piston which is sufficient to form a battery part so that upon removal from the mold the batter part is substantially free of tears and cracks as well as surface irregularities.

1 . An apparatus for die cast battery part when the molten lead is in either the liquid, solid or mush state to form a finished battery part: 
 a mold having a set of faces for defining a portion of an outer surface of a battery part cavity;    a pin having a face thereon, said pin extending though the battery part cavity to form an inner face of a battery part cavity;    an inlet for delivering lead in a molten state into the battery part cavity;    a heater for maintaining the lead in a molten state when the lead in a molten state is not being delivered into the battery part cavity;    a retractable piston, said retractable piston having a battery part face thereon for forming the battery part cavity into a closed volume, said battery part face extending in a side-to-side condition to adjoin the set of faces in the battery part cavity, said retractable piston positionable in a first condition to allow the lead in a molten state to flow into the battery part cavity, said retractable piston driveable toward the battery part cavity to close the volume of the battery part cavity to thereby shut off the flow of the lead in a molten state into the battery part cavity and to decrease the closed volume of the battery part cavity by bringing the battery part face toward the battery part cavity to shrink the volume of the battery part cavity without disrupting a faces on a solidifying battery part solidifying therein to produce the battery part with an exterior finished surface.    
   
   
       2 . The apparatus of  claim 1  wherein the retractable piston has a cavity for sliding along a pin and the pressure of the lead within the battery part cavity is increased sufficiently to thereby form a battery part whereupon solidification is substantially free of tears and cracks.  
   
   
       3 . The apparatus of  claim 1  wherein the battery part face comprises an annular face.  
   
   
       4 . The apparatus of  claim 3  wherein the entire battery part face extends along a single plane.  
   
   
       5 . The apparatus of  claim 1  wherein the lead in a molten state is a lead alloy.  
   
   
       6 . The apparatus of  claim 1  the heater extends around the inlet to maintain the lead in the inlet in a molten state when the extendible piston is in an extended condition.  
   
   
       7 . The method of die casting a finished battery part while inhibiting the formation of cracks and tears comprising the steps of: 
 directing a first charge of lead in a molten state into a battery part cavity having at least one open face;    extending a retractable piston having a battery part face into the charge of molten lead in the battery part cavity to shut off the supply of molten lead to the battery part cavity; and    continuing to extend the piston to form a closed battery part cavity and to reduce the volume of lead in the battery part cavity to a sufficient volume so that upon solidification of the lead in the battery part cavity it inhibits the formation of cracks and tears in the battery part.    
   
   
       8 . The method of  claim 7  wherein the lead in the battery part cavity is in either a liquid, mush or solid state.  
   
   
       9 . The method of  claim 8  wherein the molten lead solidifies along the surface faces of the battery part cavity with at least one of the battery part faces is forced inward to reduce the volume of the battery part cavity.  
   
   
       10 . The method of  claim 9  including the step of heating the first mold part with a heater to maintain the mold in a runner in a molten state.  
   
   
       11 . The method of  claim 7  wherein a portion of the lead in a runner is back flowed therein to bring the molten lead in the battery part cavity to an intensification condition.  
   
   
       12 . The method of die casting a finished battery part comprising the steps of: 
 injecting a molten lead containing metal into a battery part cavity having a first volume defined by a set of mold faces; and    decreasing the first volume of the battery part cavity by forcing at least one of the mold faces toward the battery part cavity to decrease the peripheral surface area while the molten lead in the battery part cavity is at least partially in an unsolidified state; and    maintaining the decreased volume during a solidification of a battery part in the battery part cavity to thereby inhibit the formation of cracks and tears in a die cast battery part.    
   
   
       13 . The method of  claim 12  wherein the battery part cavity is formed with a cylindrical interior surface and an annular end face.  
   
   
       14 . The method of die casting a finished battery part while minimize cracks and voids in the battery part comprising the steps: 
 forming a mold with the mold defining a plurality of faces of a first portion of a battery part mold cavity;    forming a gate passage fluidly connected to the first portion of the battery part mold cavity;    forming a moveable member, the moveable member having a portion defining a further face of the battery part mold cavity with the plurality of faces and the further face defined a surface bounded mold cavity when the moveable member is in a closed condition;    pouring a lead containing metal in a fluid state into the gate of the mold when the mold cavity is in an open condition;    allowing the lead containing metal to fill the first portion of the battery part mold cavity; and    driving the moveable member toward the first portion the battery mold part to close off the gate passageway;    continuing to drive the movable member toward the first portion of the battery mold part until the further face forms the surface bounded mold cavity and the internal pressure of the lead in the mold increases sufficiently to force lead into any solidification voids formed in the batter part; and    allowing the battery part to solidify under pressure;    removing the mold from the battery part to produce a finished battery part.    
   
   
       15 . The method of forming a finished battery part comprising the steps of: 
 pouring a lead containing metal in a liquid state into an open battery cavity defined by a first set of faces in a battery part mold;    allowing the lead containing metal to begin solidification around the first set of faces in the battery part mold;    driving a member having a portion defining a completion face toward the open battery cavity until the completion face on the first set of faces coact to form a closed peripheral surface; and    maintaining a pressure on the batter part during solidification of the metal in a liquid state to force molten lead into any solidification voids formed during solidification of the molten lead in the battery part cavity.    
   
   
       17 . A finished die cast battery part comprising; 
 a lead containing die cast battery part, said lead containing die cast battery pat having a set of bounded faces with each of said set of bounded faces adjoining each other to define a closed surface on said battery part, each of said faces formed by solidification in a mold with each of said bounded faces characterized by being free of surface imperfections when the die cast battery part is removed from a die cast mold.    
   
   
       18 . The unfinished die cast battery part of  claim 17  wherein the die cast battery part interior is substantially free of cracks and voids.  
   
   
       19 . The unfinished die cast battery part of  claim 17  wherein the die cast battery part comprises a battery terminal.  
   
   
       20 . The method of die casting a battery part comprising: 
 injecting a lead containing metal in a molten state into an open battery part cavity partially defined by a mold;    closing the battery part cavity by bringing a member with a finished mold face toward the open battery part cavity partially defined by the mold to create a closed battery part cavity to thereby prevent further lead containing metal in a molten state from entering or leaving the closed battery part cavity; and    increasing the pressure of the lead in the closed battery part cavity to force lead that is in a molten state into any solidification voids in lead in the closed battery part cavity to thereby inhibit the formation tears and cracks in the batter part.