Drill bit and method of manufacture
AssigneeNL Industries, Inc.
InventorRobert P. Radtke
Life of this patent
Estimating the term…
Abstract
A drag drill bit includes a plurality of cutter assemblies comprising synthetic polycrystalline diamonds which are held by brazing material within dimensionally controlled pockets formed in the drill bit matrix. The method of manufacturing the bit includes forming the drill bit head by powder metallurgy with a plurality of dimensionally controlled pockets, placing brazing material in communication with each pocket, locating and fixturing a cutter assembly within each pocket by force-fit and brazing the cutter assemblies to the bit head by a furnace cycle.
Claims19
A method of manufacturing a drill bit for use in association with a rotary drill stem, said bit comprising a bit head having a plurality of dimensionally controlled pockets and a plurality of cutter assemblies secured within said pockets which cutter assemblies comprise cutter face material that suffers thermal damage above a thermal degradation temperature;
- said method comprising the steps of:
- forming a drill bit head by powder metallurgy at a temperature above the cutter face material thermal degradation temperature, with said plurality of dimensionally controlled pockets each having sidewalls and being free from internal negative relief and formed to present the cutter face of each said cutter assemblies at a predetermined rake angle;
- forming said cutter assemblies, each comprising a drill blank having a cutter face and a support secured to said drill blank, wherein said support is of a material and has dimensions such that said support forms a frictional relationship with the sidewalls of a pocket without deforming said bit head when said support is force fit into said pocket and subsequently heated to a brazing temperature below the degradation temperature of said cutter face;
- placing a brazing material in communication with each of said pockets;
- force fitting said cutter assembly supports into said dimensionally controlled pockets;
- and
- brazing said cutter assembly supports within said pockets by a furnace cycle having a maximum temperature below said cutter face thermal degradation temperature.
A drill bit comprising:
- A drill bit head formed by powder metallurgy and having a plurality of dimensionally controlled pockets formed therein, which pockets have sidewalls free from internal negative relief;
- and
- a plurality of cutter assemblies, one for each of said pockets, each comprising a drill blank having a cutter face, and a support secured to said drill blank and secured to said pocket by brazing, wherein each support is of a material and has dimensions such that said support forms a frictional relationship with the sidewalls of a pocket without deforming said bit head when said support is force fit into said pocket and subsequently said cutter assemblies and said bit head are heated to a brazing temperature below the degradation temperature of said cutter face.
A drill bit comprising:
- a drill bit head having a plurality of cutter-locating pockets, said head and pockets being formed by powder metallurgy from a carbide containing matrix formed within a graphite mold having protuberances sizes slightly in excess of said pockets to allow for shrinkage during furnacing of said drill bit head;
- a cutter assembly for each of said pockets, secured to said pocket by placing a brazing material between said pocket surfaces and said cutter assembly and holding said cutter assembly in said pocket during a single cycle brazing operation by force fitting said cutter assembly in a manner inducing a frictional relationship between said pocket and said cutter assembly without deforming said drill bit head.
A method of securing a cutter assembly in a dimensionally-controlled pocket of a drill bit head, comprising the steps of:
- placing a brazing material in communication with said dimensionally-controlled pocket, said pocket being free from any internal negative relief;
- holding said cutter assembly in said dimensionally-controlled pocket by force fitting said assembly in a manner including a frictional relationship between said dimensionally controlled and said assembly without deforming said drill bit head;
- placing said drill bit head with said cutter assembly and associated brazing material in a furnace and brazing said cutter assembly within said pocket by a single furnace cycle having a maximum temperature below that which causes thermal damage to either the drill bit head or any portion of the cutter assembly.
Dependencies are inferred from the claim text.