Nest drill tube

• US 5,415,504 A
• Filed: 10/19/1993
• Issued: 05/16/1995
• Est. Priority Date: 10/21/1992
• Status: Expired due to Fees

• Current Assignee: Barry Wolf Farms, Ltd., Teikoku Tsushin Kogyo Company Limited
• Original Assignee: Barry Wolf Farms, Ltd.
• Inventors: McEwan, Murray, Wolf, Barry J.
• Primary Examiner(s): Howell, Daniel W.
• Application Number:
  US08/138,055
• Time in Patent Office: 574 Days
• Field of Search: 408/204, 408/205, 408/207, 408/703, 30/278, 128/754, 606/180/184
• US Class Current: 408/204
• CPC Class Codes: B23B 51/04 Drills for trepanning
• CPC Class Codes: B26D 1/46 having an endless band-knife or the like
• CPC Class Codes: B26F 1/16 Perforating by tool or tools of the drill type
• CPC Class Codes: Y10S 408/703 Trepanning
• CPC Class Codes: Y10T 408/895 Having axial, core-receiving central portion

Abstract

Rigid foam material, for example, expanded polystyrene foam, is drilled using a bit that forms an annular slit in the foam material and compresses the block temporarily around the slit. This frees the core for ready removal. The drill bit has a cutting ting at the leading end with an inside cutting edge and an annular bevel leading from the cutting edge to the outside surface of the cutting ring. The cutting ring is mounted on the leading end of a tube with an inside diameter greater than the inside diameter of the cutting ring in order to clear the core and an outside diameter less than the outside diameter of the cutting ring in order to clear the surrounding foam material.

Claims

1. A drill bit comprising:

a substantially cylindrical tube having a leading end, a trailing end and predetermined inner and outer diameters, and an annular cutting ring secured to the leading end of the tube, the cutting ring having a cylindrical outside surface with an outer diameter greater than the outer diameter of the tube, a cylindrical inside surface with an inner diameter less than the inner diameter of the tube, an annular, smooth cutting edge at a leading end and the inside surface of the cutting ring and a bevelled surface leading from the cutting edge to the outside surface of the cutting ring.

2. A drill bit according to claim 1 including a chuck-engaging shank mounted on the trailing end of the tube.

3. A drill bit according to claim 1 wherein the tube has a wall thickness in the range of 0.010 inch to 0.020 inch.

4. A drill bit according to claim 1 wherein the outside diameter of the cutting ring is approximately 0.005 inch greater than the outside diameter of the tube.

5. A drill bit comprising:

a substantially cylindrical tube having concentric inner and outer surfaces, a leading end and a trailing end;

shank means secured to the trailing end of the tube for securing the tube to a rotating drill drive; and

a cutting ring secured concentrically to the leading end of the tube and having an inner cylindrical surface with a diameter less than the diameter of the inner surface of the tube, an outer cylindrical surface with a diameter greater than the diameter of the outer surface of the tube and a bevelled leading face leading from the outer cylindrical surface of the cutting ring to an annular cutting edge at the inner cylindrical surface of the cutting ring.

6. A drill bit according to claim 5 wherein the robe has a wall thickness in the range of 0.010 inch to 0.020 inch.

7. A drill bit according to claim 5 wherein the outside diameter of the cutting ring is approximately 0.005 inch greater than the outside diameter of the tube.

8. A drill bit according to claim 7 wherein the inside diameter of the cutting ring is approximately 0.004 inch less than the inside diameter of the tube.