Mold used in manufacture of drill bits and method of forming same

Abstract

A mold usable to form a drill bit body and a method for forming such a mold are disclosed. A shell is provided, the shell having a cavity. Fusible material, such as foundry sand, is provided into the cavity, then fused to form a solid insert within the shell. The solid insert is then modified, such as by machining, to form a mold having features usable to form a drill bit body having desired characteristics. Materials for forming the drill bit body can then be provided into the mold, for heating and cooling. Then, the drill bit body and mold can be removed from the shell. The shell is thereby reusable, while the mold, being formed from inexpensive fusible materials, can be removed or destroyed, if necessary, to free the drill bit body.

1 . A method for forming a drill bit body, the method comprising the steps of:
 providing a fusible material into a shell;   fusing the fusible material to form a solid insert within the shell;   modifying the solid insert to form a mold comprising features usable to form a drill bit body;   providing at least one drill bit body material into the mold;   heating said at least one drill bit body material, wherein said heated at least one drill bit body material flows into the features of the mold;   cooling said at least one drill bit body material to form the drill bit body within the mold; and   removing the drill bit body and the mold from the shell.   
     
     
         2 . The method of  claim 1 , wherein the fusible material comprises a mixture of silica sand and a binder, a resin, a plasticizer, one or more polymers, or combinations thereof. 
     
     
         3 . The method of  claim 1 , wherein the fusible material comprises foundry sand. 
     
     
         4 . The method of  claim 1 , wherein the step of fusing the fusible material to form the solid insert comprises heating the fusible material, the generally rigid shell, or combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the step of modifying the solid insert to form the mold comprises machining the solid insert, milling the solid insert, or combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein said at least one drill bit body material comprises tungsten carbide, nickel, monel, steel, cobalt, iron, other transition metals, or combinations thereof. 
     
     
         7 . The method of  claim 1 , further comprising the step of removing the mold from the drill bit body by breaking the mold, heating the mold to cause disassociation of the fusible material, or combinations thereof. 
     
     
         8 . The method of  claim 1 , further comprising the steps of removing the mold intact from the drill bit body and inserting the mold into the shell for reuse. 
     
     
         9 . The method of  claim 1 , further comprising the step of modifying the drill bit body to provide desired features to the drill bit body. 
     
     
         10 . The method of  claim 1 , further comprising the step of providing an additional material to at least a portion of the mold, wherein the step of heating said at least one drill bit body material causes the additional material to melt whereby a region of the drill bit body is provided with a generally smooth finish. 
     
     
         11 . The method of  claim 10 , wherein the additional material comprises clay, graphite powder, or combinations thereof. 
     
     
         12 . The method of  claim 10 , wherein the step of providing the additional material to at least a portion of the mold comprises providing the additional material to one or more cracks, damaged areas, or combinations thereof within the mold to prevent formation of irregularities in the drill bit body. 
     
     
         13 . The method of  claim 1 , wherein the step of providing said at least one drill bit body material into the mold comprises providing a powdered metal matrix material into the mold and providing one or more metal alloys in fluid communication with the powdered metal matrix material, and wherein the step of melting said at least one drill bit body material comprises melting the one or more metal alloys and permitting the one or more metal alloys to flow into spaces within the powdered metal matrix material. 
     
     
         14 . A mold for forming a drill bit body, the mold comprising:
 a shell having a cavity; and   a removable insert formed from a fusible material, wherein the removable insert comprises features usable to form a drill bit body, and wherein the removable insert can be filled with at least one drill bit body material which when heated and cooled forms a drill bit body comprising the features of the removable insert.   
     
     
         15 . The mold of  claim 14 , wherein the fusible material comprises a mixture of silica sand and a binder, a resin, a plasticizer, one or more polymers, or combinations thereof. 
     
     
         16 . The mold of  claim 14 , wherein the fusible material comprises foundry sand. 
     
     
         17 . The mold of  claim 14 , wherein the shell comprises graphite. 
     
     
         18 . The mold of  claim 14 , wherein said at least one drill bit body material comprises tungsten carbide, nickel, monel, steel, cobalt, iron, other transition metals, or combinations thereof 
     
     
         19 . The mold of  claim 14 , further comprising an additional material disposed within at least a portion of the removable insert, wherein the additional material melts when heated such that a region of the drill bit body is provided with a generally smooth finish. 
     
     
         20 . A method for forming a mold usable to manufacture a drill bit body, the method comprising the steps of:
 providing a shell having a cavity;   providing a fusible material into the cavity;   fusing the fusible material to form a solid insert within the shell; and   modifying the solid insert to form a mold comprising features usable to manufacture the drill bit body.   
     
     
         21 . The method of  claim 20 , wherein the fusible material comprises a mixture of silica sand and a binder, a resin, a plasticizer, one or more polymers, or combinations thereof. 
     
     
         22 . The method of  claim 20 , wherein the fusible material comprises foundry sand. 
     
     
         23 . The method of  claim 20 , wherein the step of fusing the fusible material to form the solid insert comprises heating the fusible material, the generally rigid shell, or combinations thereof 
     
     
         24 . The method of  claim 20 , wherein the step of modifying the solid insert to form the mold comprises machining the solid insert, milling the solid insert, or combinations thereof