Cutting element pocket with relief features

Abstract

A bit has a bit body. A pocket is formed in a surface of the bit body. The pocket has an opening at the surface and is defined by a rear wall with a sidewall extending between the rear wall and the surface. The pocket includes a stress relief feature at a front end of the sidewall to reduce stress concentrations in the bit body at or near the pocket, a stress relief feature at a rear end of the sidewall to reduce stress concentrations in the bit body at or near the pocket, or stress relief features at both front and rear ends of the sidewall.

What is claimed is: 
     
         1 . A bit, comprising:
 a bit body;   a plurality of blades extending from the bit body, the plurality of blades having a plurality of pockets each at least partially defined by a rear wall and a sidewall, at least one of the plurality of pockets including an annular stress relief element in the sidewall or rear wall thereof; and   an insert brazed into the at least one of the plurality of pockets.   
     
     
         2 . The bit of  claim 1 , the annular stress relief element being a recess around a full circumference of the rear wall of the pocket. 
     
     
         3 . The bit of  claim 1 , the insert being a cutting element or depth of cut limiter. 
     
     
         4 . The bit of  claim 1 , the insert having a lower coefficient of thermal expansion than the bit body. 
     
     
         5 . The bit of  claim 1 , the annular stress relief element being a relief opening in the sidewall and extending around a full circumference of the pocket adjacent front portion of the pocket that is opposite the rear wall. 
     
     
         6 . A bit, comprising:
 a bit body; and   a cutting face coupled to the bit body, the cutting face including a surface having at least one pocket therein, the at least one pocket being at least partially defined by a rear wall and a sidewall, the at least one pocket including a relief opening at an interface of the at least one pocket and the surface, and extending around at least 75% of a perimeter of the at least one pocket.   
     
     
         7 . The bit of  claim 6 , the relief opening extending around an entirety of the perimeter of the at least one pocket. 
     
     
         8 . The bit of  claim 6 , the relief opening having an opening depth and the at least one top pocket having a pocket depth, an opening depth ratio of the opening depth to the pocket depth being between 1:20 and 1:2. 
     
     
         9 . The bit of  claim 6 , the relief opening including an opening lateral extension extending laterally beyond a width of the pocket, the relief opening having an opening extension ratio of the opening lateral extension to a pocket width that is between 0.10:1 and 0.04:1. 
     
     
         10 . The bit of  claim 6 , the relief opening having an opening lateral extension extending laterally beyond a width of the pocket and an opening depth, the opening depth and opening lateral extension defining an opening aspect ratio between 15:1 and 1:15. 
     
     
         11 . The bit of  claim 6 , the relief opening having a profile that is at least partially curved or at least partially linear. 
     
     
         12 . The bit of  claim 6 , further comprising an insert brazed in the at least one pocket with braze material, the insert having a different coefficient of thermal expansion than the bit body. 
     
     
         13 . The bit of  claim 12 , the at least one pocket having a pocket width less than a combined width of the insert and the braze material below 100° F. (37.8° C.). 
     
     
         14 . The bit of  claim 6 , the at least one pocket including a top pocket and the bit further comprising an insert in the top pocket, the sidewall of the top pocket applying a compression force to the insert. 
     
     
         15 . A bit, comprising:
 a bit body; and   a blade extending from the bit body, the blade including a surface having at least one pocket therein, the at least pocket being defined by a sidewall and rear wall, the at least one pocket including a relief recess between the rear wall and the sidewall, the relief recess having a recess depth beyond a pocket depth of the at least one pocket.   
     
     
         16 . The bit of  claim 15 , the relief recess being an annular recess surrounding the rear wall of the pocket. 
     
     
         17 . The bit of  claim 15 , a recess depth ratio of the recess depth to the pocket depth being between 1:15 and 1:5. 
     
     
         18 . The bit of  claim 15 , the relief recess having a recess width and the at least one pocket having a pocket width, a recess width ratio of the recess width to the pocket width being between 1:10 and 1:3. 
     
     
         19 . The bit of  claim 15 , the relief recess having a lateral extension beyond at least a portion of the sidewall and an extension-recess ratio of the lateral extension to a recess width being between 1:100 and 1:2. 
     
     
         20 . The bit of  claim 15 , the relief recess having a profile that is at least partially curved and at least partially linear, with a curve-linear ratio of a curved portion width to a linear portion width between 50:1 and 1:50.