Earth boring drill bit with shell supporting an external drilling surface

The method of claim 9 wherein heating the outer shell comprises:

• placing a first induction heater within said shell;
• placing a second induction heater adjacent the interior of said shell;
• and
• turning on said induction heaters.

A method for making an earth boring drill bit comprising:

• introducing matrix powder in a mold to form an outer shell of said bit, said shell having an external surface adapted to carry cutting elements and an internal surface defined by the matrix powder adapted for connection to a bit mandrel;
• infiltrating the matrix powder;
• urging the bit mandrel against said internal surface after infiltrating the matrix powder;
• connecting the mandrel to said shell about the periphery of each.

A method for making an earth boring drill bit comprising:

• forming an outer shell of said bit, said shell having an external surface adapted to carry cutting elements and an internal surface adapted for connection to a bit shank, including:
• inserting an upper mold body into a mold;
• substantially filling the space between said mold and said upper mold body with matrix powder;
• and
• infiltrating the matrix powder;
• heating the outer shell;
• engaging the bit shank with the internal surface of said outer shell;
• and
• cooling the shell thereby causing the same to contract into further engagement with said shank.

A method for making an earth boring drill bit comprising:

• forming an outer shell of said bit, said shell having an external surface adapted to carry cutting elements and an internal surface adapted for connection to a bit shank;
• heating the outer shell, including:
• placing a first induction heater within said shell;
• placing a second induction heater adjacent the interior of said shell;
• and
• turning on said induction heaters;
• engaging the bit shank with the internal surface of said outer shell;
• and
• cooling the shell thereby causing the same to contract into further engagement with said shank.

A method for making an earth boring drag-type drill bit comprising:

• forming an outer shell of said bit around a ductile interior shell, said shell having an external surface adapted to carry drag-type cutting elements and said interior shell having an internal surface adapted for connection to a bit shank;
• heating the shells;
• engaging the bit shank with the internal surface of said interior shell;
• and
• cooling the shells thereby causing the same to contract into further engagement with said shank.

A method for making an earth boring drill bit comprising:

• forming an outer shell of said bit by infiltrating matrix powder in a mold, said shell having an external surface adapted to carry cutting elements and an internal surface adapted for connection to a bit shank;
• heating the outer shell, including the steps of:
• placing a first induction heater within said shell;
• placing a second induction heater adjacent the interior of said shell;
• and
• turning on said induction heaters;
• engaging the bit shank with the internal surface of said outer shell;
• and
• cooling the shell thereby causing the same to contract into further engagement with said shank.

A method for making an earth boring drill bit comprising:

• infiltrating a matrix powder in a mold to form an outer shell of said bit, said shell having an external surface adapted to carry cutting elements and a bore for receiving a bit shank, including:
• inserting an upper mold body into the mold;
• and
• substantially filling the space between said mold and said upper mold body with matrix powder;
• and
• forming a plurality of radially extending ridges and grooves disposed between said shank and the radially inner surface of said bore, said ridges being received in said grooves when said shank is inserted in said bore;
• inserting the bit shank into said bore;
• and
• connecting the shank to said shell about the periphery of each.

A method for making an earth boring drill bit comprising:

• forming an outer shell of said bit, said shell having an external surface adapted to carry cutting elements and an internal surface having a first annular shoulder, said internal surface being adapted for connection to a bit shank having a second annular shoulder;
• heating the outer shell;
• engaging the bit shank with the internal surface of said outer shell until said first and second annular shoulders are substantially opposite one another;
• and
• cooling the shell thereby causing the first and second shoulders to contract into engagement with one another.

A method for making an earth boring drill bit comprising:

• infiltrating a matrix powder in a mold by inserting an upper mold body into the mold and packing the space between said mold and said upper mold body with matrix powder to form an outer shell of said bit, said shell having an external surface adapted to carry cutting elements and a bore for receiving a bit mandrel;
• forming a plurality of radially extending ridges and grooves disposed between said shank and the radially inner surface of said bore, said ridges being received in said grooves when said shank is inserted in said bore;
• inserting the bit mandrel into said bore after infiltrating the matrix powder;
• and
• connecting the mandrel to said shell about the periphery of each.