Drill bit with dual reaming rows

A rolling cutter drill bit for forming bore holes in earthen formations having a plurality of rolling cone cutters, at least two of said cutters having gage faces adapted to engage the sidewall of the borehole, each of said two cutters having multiple rows of inserts retained in receiving sockets on the outer surfaces of the cutter, each of said two cutters including:

• a gage row of inserts positioned at the gage corner of the cutter;
• a first reaming row of inserts positioned entirely on the gage face of the cutter in an interlocking relationship with the gage row of inserts;
• and a second reaming row of inserts positioned on the gage face of the cutter further from said gage row than said first reaming row;
• said second reaming row being in a non-interlocking relationship with said gage row and said first reaming row, the inserts of the first reaming row having exposed gage-reaming, wear-resistant surfaces, the whole of which surfaces are exposed only at the gage face of the cutter;
• and the number of said first reaming row inserts on the first of said two cutters being less than the number of said first reaming row inserts on the second of said two cutters.

A rolling cutter drill bit for forming bore holes in earthen formations having a plurality of rolling cone cutters, at least two of said cutters having gage faces adapted to engage the sidewall of the borehole, each of said two cutters having multiple rows of inserts retained in receiving sockets on the outer surfaces of the cutter, each of said two cutters comprising:

• a gage row of inserts positioned at the gage corner of the cutter;
• a first reaming row of inserts positioned on the gage face of the cutter in an interlocking relationship with the gage row of inserts;
• and a second reaming row of inserts positioned on the gage face of the cutter further from said gage row than said first reaming row;
• said second reaming row being in a non-interlocking relationship with said gage row and said first reaming row;
• and the diameter of said first reaming row inserts on the first of said two cutters being less than the diameter of said first reaming row inserts on the second of said two cutters.

A rolling cutter drill bit for forming bore holes in earthen formations having a plurality of rolling cone cutters, at least one of said cutters having a gage face adapted to engage the sidewall of the bore hole, said one of said cutters having multiple rows of inserts retained in receiving sockets on the outer surfaces of the cutter, including:

• a gage row of inserts positioned adjacent to said gage face to engage the outer periphery of the hole bottom;
• a first reaming row of inserts positioned on said gage face of said cutter in an interlocking relationship with said gage row of inserts;
• and a second reaming row of inserts positioned on said gage face of the cutter further from said gage row than said first reaming row;
• said second reaming row being in a non-interlocking relationship with said gage row and said first reaming row and said second reaming row inserts being larger in diameter than said first reaming row inserts.

A rolling cutter drill bit for forming bore holes in earthen formations having a plurality of rolling cone cutters, at least one of said cutters having a gage face adapted to engage the sidewall of the bore hole, said one of said cutters having multiple rows of inserts retained in receiving sockets on the outer surfaces of the cutter, including:

• a gage row of inserts positioned adjacent to said gage face to engage the outer periphery of the hole bottom;
• a first reaming row of inserts positioned on said gage face of said cutter in an interlocking relationship with said gage row of inserts;
• and a second reaming row of inserts positioned on said gage face of the cutter further from said gage row than said first reaming row;
• said second reaming row being in a non-interlocking relationship with said gage row and said first reaming row, and the depth of said receiving sockets of said second reaming row being larger than the depth of said receiving sockets of said first reaming row.

A rolling cutter drill bit for forming bore holes in earthen formations having a plurality of rolling cone cutters, at least one of said cutters having a gage face adapted to engage the sidewall of the bore hole, said one of said cutters having multiple rows of inserts retained in receiving sockets on the outer surfaces of the cutter, including:

• a gage row of inserts positioned adjacent to said gage face to engage the outer periphery of the hole bottom;
• a first reaming row of inserts positioned entirely on said gage face of said cutter in an interlocking relationship with said gage row of inserts;
• and a second reaming row of inserts positioned on said gage face of the cutter further from said gage row than said first reaming row;
• said second reaming row being in a non-interlocking relationship with said gage row and said first reaming row, the inserts of the first reaming row having exposed gage-reaming, wear-resistant surfaces, the whole of which surfaces are exposed only at the gage face of the cutter, and said non-interlocking relationship between said gage row and said second reaming row comprising a minimum distance between insert sockets of said gage row and insert sockets of said second reaming row of at least 0.050 inch.

A rolling cutter drill bit for forming bore holes in earthen formations having a plurality of rolling cone cutters, at least one of said cutters having a gage face adapted to engage the sidewall of the bore hole, said one of said cutters having multiple rows of inserts retained in receiving sockets on the outer surfaces of the cutter, including:

• a gage row of inserts positioned adjacent to said gage face to engage the outer periphery of the hole bottom;
• a first reaming row of inserts positioned entirely on said gage face of said cutter in an interlocking relationship with said gage row of inserts;
• and a second reaming row of inserts positioned on said gage face of the cutter further from said gage row than said first reaming row;
• said second reaming row being in a non-interlocking relationship with said gage row and said first reaming row, the inserts of the first reaming row having exposed gage-reaming, wear-resistant surfaces, the whole of which surfaces are exposed only at the gage face of the cutter, and said non-interlocking relationship between said first reaming row and said second reaming row comprises a minimum distance between insert sockets of said first reaming row and insert sockets of said second reaming row of at least 0.050 inch.