Title: Rock drill bit inserts with hollow bases

Abstract: A rock bit for drilling hard formations has a bit body with a plurality of rolling cone cutters mounted on it for rotation with rotation of the bit body. The cutters each have a plurality of recesses in their outer surfaces and a tungsten carbide insert is interference fitted into each of said recesses. A large diameter rock bit has such inserts larger than about 3/4 inch diameter and a cavity is provided in the cylindrical base of such an insert. The cavity has a volume in the range of from about 15 to 30% of the volume of the cylindrical base and extends into the cylindrical base a distance of at least about 40% of the diameter of the base. The depth of the recess is more than half of the length of the portion of the insert that grips the recess in which it is inserted. Large savings in expensive tungsten carbide can be made without decreasing performance of the tungsten carbide inserts.

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Inventors: Garner, Lloyd L. (San Clemente, CA, US)
Herrick, George R. (Irvine, CA, US)
Harris, Charles R. (Whittier, CA, US)

Application Number: 846570
Filing Date: 1977-10-28
Publication_date: 1979-04-24
Assignee: Smith International, Inc. (Newport Beach, CA)
Primary Class(es): 175/374 175/370, 175/372, 175/426, 175/432
Other Classes:
US Patent Ref:

3388757	Jun, 1968	Fittinger	175/410.
3599737	Aug, 1971	Fischer	175/410.
3727705	Apr, 1973	Newman	175/374.

Other Refs:
Primary Examiner: Purser, Ernest R.
Assistant Examiner: Favreau, Richard E.
Attorney: Christie, Parker & Hale