Drill bit device

Abstract

Drill bit construction having a removable lead screw and a body which has a conically shaped work facing surface. With generally triangularly shaped cut-away segments. Each of the segments has a cutting edge either in the form of a detachable blade or integrally formed into the body. The body itself is also detachably removable from the drill shaft or shank. In smaller diameter embodiments a spiral member recedes from the shaft adjacent the head for removing shaving as the bit proceeds through the wood.

We claim: 
     
       1. A boring .[.took.]. .Iadd.tool.Iaddend., comprising a. a generally circular drill bit body having a work face and a back end, said work face defining a substantially cone-shaped surface extending rearwardly and outwardly at an angle of about 30°, said body also having a lead screw cavity in said work face generally centrally thereof and a pair of generally opposed cut-away segments extending from said work face to the back end of said body,   b. a detachable lead screw including a shank portion received in said lead screw cavity,   c. said body also having a center section extending rearwardly and including a shaft cavity for mounting said body on a shaft for rotation by drill means,   d. a cutting edge means in each of said segments, and   e. means in the center section of said body for detachably securing said lead screw to said body and said body to said shaft.   
     
     
       2. The boring tool according to claim 1 and wherein said body is provided with a cylindrical, rearwardly extending guide surface adjacent the outer edge of said cone surface which is of greater diameter than said center section. 
     
     
       3. The boring tool according to claim 2 and wherein said guide surface is defined by a skirt which is radially spaced from said center section. 
     
     
       4. The boring tool according to claim 1 and wherein said cutting edges are formed on detachable blade means which extend generally from said lead screw generally to the outer edge of said cone surface. 
     
     
       5. The boring tool according to claim 4 and wherein said detachable blade means has an outer planar surface angling slightly away from and rearwardly of said cutting edge. 
     
     
       6. The boring tool according to claim 2 and wherein said center section is radially inwardly offset of said cylindrical surface and extends rearwardly thereof. 
     
     
       7. A boring tool, comprising a. a generally circular drill bit body having a work face and a back end, said body also having a lead screw cavity in said work face and extending through said body generally centrally thereof, and a pair of opposed cut-away segments extending from said work face to the back end of said body, said segments also having cutting edge means therein,   b. a detachable lead screw including a shank portion received in said cavity and extending rearwardly of the back end of said body,   c. shaft means on which said body is mounted including a mounting base having a shank cavity to receive said shank,   d. means in said base securing the shank in said shank cavity and holding said lead screw and body on said mounting base, and   e. means for securing said base, lead screw and body against rotation relative to each other.   
     
     
       8. The boring tool of claim 7 and wherein said securing means is on either the base or body and includes coacting securing means on the other of either the base or body. 
     
     
       9. The boring tool of claim 7 and wherein a spiral member extends from the base adjacent the back end of said body to evacuate shavings from said segment areas. 
     
     
       10. The boring tool of claim 9 and wherein said base has flat surfaces generally rearwardly of said segment areas. 
     
     
       11. A boring tool, comprising a. a generally circular drill bit body having a work face and a back end, said work face defining a substantially cone-shaped surface extending rearwardly and outwardly at an angle of about 30°, said body also having a lead screw cavity in said work face and extending through said body generally centrally thereof, and a pair of opposed cut-away segments extending from said work face to the back end of said body, said segments also having cutting edge means therein,   b. a detachable lead screw including a shank portion received in said cavity and extending rearwardly of the back end of said body,   c. shaft means on which said body is mounted including a mounting base having a shank cavity to receive said shank,   d. means in said base securing the shank in said shank cavity and holding said lead screw and body on said mounting base, and   e. means for securing said base, lead screw and body against rotation relative to each other.   
     
     
       12. The boring tool of claim 11 and wherein said securing means is on either the base or body and includes coacting securing means on the other of either the base or body. 
     
     
       13. The boring tool of claim 11 and wherein a spiral member extends from the base adjacent the back end of said body to evacuate shaving from said segment areas. 
     
     
       14. The boring tool of claim 13 and wherein said base has flat surfaces generally rearwardly of said segment areas. .Iadd. 15. A boring tool, comprising: a. generally circularly defined drill bit body having a work face and a rear face, said body also having a lead screw cavity in said work face and extending through said body generally centrally thereof, and a pair of opposed cut-away segments extending from said work face to the rear face of said body, said segments also having cutting edge means therein on the work face thereof,   b. a detachable lead screw including a shank portion received in said cavity and extending rearwardly of the rear face of said body,   c. shaft means on which said body is mounted including a mounting base having a shank cavity to receive said shank,   d. first means in said base securing the shank in said shank cavity and holding said lead screw and body on said mounting base, and   e. second means for securing said base and body against rotation relative to each other. .Iaddend..Iadd. 16. The boring tool of claim 15 and wherein said base is formed to provide unobstructed areas generally rearwardly of said segment areas to evacuate shavings from said segment areas. .Iaddend..Iadd. 17. The boring tool of claim 15 and wherein a spiral member extends generally rearwardly from the base to evacuate shavings from said segment areas. .Iaddend. .Iadd. 18. A boring tool, comprising:   a. a generally circular drill bit body having a work face and a back end, said work face defining a substantially cone-shaped surface extending rearwardly and outwardly at an angle of about 30°, said body also having a lead screw cavity in said work face generally centrally thereof, and a pair of opposed cut-away segments extending from said work face to the back end of said body, said segments also having cutting edge means therein,   b. a detachable lead screw including a shank portion received in said lead screw cavity,   c. shaft means including a mounting portion to which said body is secured for nonrotational movement relative thereto, and,   d. means securing said shank in said lead screw cavity for securely holding said lead screw and body together and against rotation relative to each other. .Iaddend..Iadd. 19. The boring tool of claim 18 and wherein a spiral member extends generally rearwardly from a point adjacent the back end of said body to evacuate shavings from said segment areas. .Iaddend.