Drilling equipment and method

Abstract

A drill bit is provided for drilling holes in hard, reinforced material, including reinforced concrete. According to one aspect of the invention, wear-resistant inserts are provided in a cross-shaped pattern. The inserts ensure that the entire bottom surface of the drilled hole is engaged during each drill bit revolution. The inserts may be secured in pockets or slots. Fluid entry ports may be located between the inserts for efficient handling of drilling fluid and removal of drilled material, without impairing the structural integrity of the drill bit. According to another aspect of the invention, the drilling surface is separated into two or more stages to increase drilling efficiency, especially through composite material such as reinforced concrete.

What is claimed as new and desired to be protected by Letters Patent of the United States is:  
     
         1 . A drill tool for drilling into reinforced material, said drill bit comprising: 
 a head portion having ports for flowing drilling fluid toward said reinforced material, said head portion being formed of a first material; and    inserts for engaging said reinforced material, said inserts being located in said head portion, said inserts being formed of a second material, and said second material having greater wear resistance than said first material.    
     
     
         2 . The drill tool of  claim 1 , further comprising a shank for applying axial thrust and torque to said head portion.  
     
     
         3 . The drill tool of  claim 2 , further comprising drilled passageways for providing fluid communication from an inner portion of said shank to said ports of said head portion.  
     
     
         4 . The drill tool of  claim 3 , wherein said drilled passageways intersect each other in said inner portion of said shank.  
     
     
         5 . The drill tool of  claim 1 , further comprising outer passageways formed in an outer surface of said head portion for flowing said drilling fluid away from said inserts.  
     
     
         6 . The drill tool of  claim 5 , further comprising recessed portions in said head portion for directing said drilling fluid toward said outer passageways.  
     
     
         7 . The drill tool of  claim 6 , wherein said ports are located in said recessed portions.  
     
     
         8 . The drill tool of  claim 1 , wherein said inserts include a center insert surrounded by first and second radial inserts forming a cross-shaped pattern.  
     
     
         9 . The drill tool of  claim 8 , wherein the length of said center insert is greater than the width of said first and second radial inserts.  
     
     
         10 . The drill tool of  claim 9 , wherein said second radial inserts are longer than said first radial inserts.  
     
     
         11 . A multi-stage drill bit for forming a cylindrical hole in a reinforced material, said multi-stage drill bit comprising: 
 a pilot stage for forming a pilot hole, said pilot stage including ports for flowing drilling fluid into said pilot hole, and wear-resistant inserts for engaging said reinforced material; and    a second stage for enlarging said pilot hole, said second stage having a greater diameter than said pilot stage, and said second stage including inserts.    
     
     
         12 . The multi-stage drill bit of  claim 11 , wherein said wear-resistant inserts of said pilot stage and said second stage have cutting edges with a roof angle in the range of from about 34 to 37 degrees.  
     
     
         13 . The multi-stage drill bit of  claim 12 , wherein said cutting edges are formed of wear-resistant material.  
     
     
         14 . The multi-stage drill bit of  claim 13 , wherein said pilot stage and said second stage include passageways for directing drilling fluid away from said inserts.  
     
     
         15 . A method of drilling a hole into reinforced concrete, said method comprising the steps of: 
 using a pilot stage to drill through a metal reinforcement bar; and    subsequently, using a larger diameter second stage to drill through said reinforcement bar; and    transmitting torque through said larger diameter second stage to said pilot stage.    
     
     
         16 . The method of  claim 15 , further comprising the step of flowing drilling fluid through interior passageways in said pilot stage.  
     
     
         17 . The method of  claim 16 , further comprising the step of flowing said drilling fluid and drilled material around said second stage.  
     
     
         18 . The method of  claim 16 , wherein said step of using said pilot stage to drill though said reinforcement bar includes the step of engaging said bar with wear-resistant inserts.  
     
     
         19 . The method of  claim 18 , wherein an elongated central insert forms a central portion of said pilot hole, and radially outer inserts form an annular portion of said pilot hole surrounding said central portion of said pilot hole, such that said inserts define overlapping rotational paths that together cover the entire attack face of said pilot stage.  
     
     
         20 . The method of  claim 19 , wherein fluid flow ports are located between said radially outer inserts.