Drill bit having shear and pick-type cutters

Abstract

A drill bit includes a bit body defining a plurality of blades extending from a selected distance from an axis of rotation of the bit body to a gage face. A plurality of only gouging cutters is mounted on the bit body. At least one of the plurality of blades has a blade top surface longitudinally behind the tips of the gouging cutters at a selected distance from the tips of the gouging cutters.

1 - 19 . (canceled) 
     
     
         20 . A drill bit, comprising:
 a bit body having a plurality of only gouging cutters mounted on the bit body; and   means for limiting cutting depth of the gouging cutters to a selected distance longitudinally behind tips of the gouging cutters.   
     
     
         21 . The bit of  claim 20  further comprising a plurality of blades extending from a selected distance from an axis of rotation of the bit body to a gage face, wherein a blade top surface of each of the plurality of blades defines the means for limiting cutting depth. 
     
     
         22 . The bit of  claim 21  wherein at least one of the plurality of blades further comprises a plurality of shear cutters affixed thereon, and wherein the gouging cutters extend a selected distance longitudinally ahead of a cutting surface defined by the shear cutters, the gouging cutters mounted on at least one of the bit body or on a surface of at least one of the plurality of blades. 
     
     
         23 . The bit of  claim 22  wherein the gouging cutters are mounted to the bit body rotationally ahead of the shear cutters. 
     
     
         24 . The bit of  claim 22  wherein the gouging cutters are mounted to the bit body rotationally behind the shear cutters. 
     
     
         25 . The bit of  claim 22  wherein the shear cutters comprise at least one of polycrystalline diamond compact cutters, tungsten carbide cutters, diamond impregnated tungsten carbide cutters and cubic boron nitride cutters. 
     
     
         26 . The bit of  claim 22  wherein the shear cutters are disposed at a backrake angle in a range of 10 to 30 degrees. 
     
     
         27 . The bit of  claim 22  wherein the shear cutters are disposed at a backrake angle of about 20 degrees. 
     
     
         28 . The bit of  claim 22  wherein the selected longitudinal extension of the gouging cutters is within a range of ⅛ inch (3 millimeters) to ¾ inch (19 millimeters) beyond the defined cutting surface. 
     
     
         29 . The bit of  claim 28  wherein the selected longitudinal extension of the gouging cutters is about 0.5 inches (13 millimeters) beyond the defined cutting surface. 
     
     
         30 . The bit of  claim 20  wherein the gouging cutters comprise a steel body and a tip made from at least one of tungsten carbide, diamond impregnated tungsten carbide, polycrystalline diamond and cubic boron nitride. 
     
     
         31 . The bit of  claim 20  wherein the gouging cutters are disposed at a forward rake angle in a range of 15 to 45 degrees. 
     
     
         32 . The bit of  claim 31  wherein the forward rake angle of the gouging cutters is about 15 degrees. 
     
     
         33 . The bit of  claim 20  wherein a selected longitudinal extension of the gouging cutters is within a range of ⅛ inch (3 millimeters) to ¾ inch (19 millimeters) beyond the means for limiting cutting depth. 
     
     
         34 . The bit of  claim 33  wherein the selected longitudinal extension of the gouging cutters is about 0.5 inches (13 millimeters). 
     
     
         35 . The bit of  claim 20  further comprising at least one gage insert in the gage face of each of the blades. 
     
     
         36 . The bit of  claim 35  wherein the gage inserts comprise at least one of polycrystalline diamond, cubic boron nitride, diamond impregnated tungsten carbide and tungsten carbide. 
     
     
         37 . The bit of  claim 20  wherein the gouging cutters are rotatably mounted on the bit body. 
     
     
         38 . The bit of  claim 20  wherein the gouging cutters are removably mounted on the bit body. 
     
     
         39 . The bit of  claim 38  wherein each of the gouging cutters is locked into the bit body by a snap ring.