Abstract:
Pilot drill with coupon retainer and hot tapping machine using the same that positively retains a coupon cut out by a hole saw. The pilot drill bit has a shank having a driving end for attachment to a drill driver and a cutting end having a cutting edge thereon, the cutting edge being sized to drill a hole of selected diameter through a workpiece, and a movable retaining finger mounted on the shank adjacent the cutting edge, the movable retaining finger having a first position fitting within the cutting diameter of the cutting edge and a second, extended position where a portion thereof lies outside the cutting diameter to retain on the drill shank a workpiece through which the drill bit may have drilled.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of drills, and more particularly to pilot drills for use with hole saws. 
     2. Prior Art 
     In urban areas, there are underground pressurized service mains which supply pressurized fluid for residential and commercial needs. Most often, these fluids are potable water and fuel gas. In some areas, other pressurized fluids are present. 
     When it becomes necessary to add a new service tap on the line, it is inconvenient to shut down the service line to add a tee. Such a shutdown would cut off service to others on that service main. This problem has been overcome by attaching a saddle to the service line. The saddle has a valve therein, and a piloted hole saw is introduced through the open valve. A well-known structure for accomplishing this is taught in Weiler, U.S. Pat. No. 5,893,686, the entire disclosure of which is incorporated herein by this reference. Such a system is sold by Raydon Industries, LLC, of Huntington beach, Calif. as The SIMTAP Drilling Machine. However, a problem can arise when the pilot drill and hole saw are withdrawn after cutting through the main. In particular, the coupon cut out by the hole saw sometimes falls into the supply main. This is undesirable, and frequently unacceptable, as it should be withdrawn with the pilot drill and hole saw every time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of the use of the present invention with a hot tapping machine for tapping into pressurized mains. 
         FIG. 2  is an exploded view of a hot tapping machine with a pilot drill in accordance with the present invention. 
         FIGS. 3 and 4  are illustrations of one embodiment of pilot drill in accordance with the present invention. 
         FIGS. 5 and 6  are partial cross sections illustrating the operation of the pilot drill of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First referring to  FIG. 1 , a schematic illustration of an individual using a hand drill  20  to power a SIMTAP Drilling Machine, generally indicated by the numeral  22 , to provide a new tap into a main  24  may be seen. The SIMTAP operates in conjunction with a saddle  26  clamped around the main  24  using U bolts  28 , the saddle being adapted for a ball valve  30  to be screwed there onto. The SIMTAP generally is provided with a plurality of adapters, such as adapter  32 , one of which will readily screw onto any of the commonly used ball valves  30 , with a body  34  screwing into any of the adapters  32 , the body  34  receiving a rotatable shaft  36  and sealing with respect thereto. In that regard, the body  34 , adapter  32 , ball valve  30  and saddle  26  provide a sealed assembly so that when a hole is made in the main  24 , the pressurized fluid in the main will be confined to within the assembly. 
     In operation, hand drill  20  is used to turn shaft  36  having a hole saw at the inner end thereof passing through the open ball valve  30  to drill a hole in the pressurized main to provide a new tap therein. Once the hole has been drilled, shaft  36  with the hole saw thereon is withdrawn back through the ball valve, and the ball valve closed, after which body  34  and adapter  32  may be removed, with the new service connection being made to the ball valve and the ball valve opened to provide the new service. 
     The basic assembly of the SIMTAP is shown in  FIG. 2 . Shaft  36  has a hexagonal end  38  for convenient and positive gripping by a drill chuck, and at the opposite end, has threaded areas  40  and  42 , one of which will receive one of two sizes of internally threaded connections at the end of commonly used hole saws  44 . 
     One aspect of the present invention is the pilot drill itself, generally indicated by the numeral  46 . In the preferred embodiment, the pilot drill has a flat region  48  at one end thereof which may be inserted into the end of shaft  36  and positively locked therein against relative rotation by setscrew  50 . The pilot drill  46  of the preferred embodiment is better illustrated in  FIGS. 3 and 4 . The specific pilot drill shown in  FIGS. 3 and 4  has tungsten carbide cutting blades  52  braised to the end of the drill, with flattened regions  54  in reasonable proximity to the cutting edge end of the drill. A hole  55  is provided through the drill substantially perpendicular to the flattened regions  54  and adjacent ends  56  of those flattened regions. Disposed through the hole  55 , and having a loose fit therein, is a wire member generally indicated by the numeral  58  having the ends bent over as shown so that the dimension, tip to tip, across the ends of the side regions  60  of the wire member is approximately equal to the diameter of the drill, that is, the diameter of the hole that the drill will form. In that regard, in the preferred embodiment, the wire  58  is a relatively rigid wire, and accordingly, preferably is bent to have a tip to tip dimension equal to or slightly less than the diameter of the hole the drill will form, though in other embodiments, particularly if the wire is purposely made more flexible, the tip to tip dimension could range from below the size to slightly larger than the hole the drill will form. 
     Referring again to  FIGS. 1 and 2 , in use, the saddle  26  is fastened to and sealed with respect to the main  24  using U bolts  28 , and the desired ball valve  30  is screwed onto the saddle. The SIMTAP Drilling Machine shown in  FIG. 2  is assembled by picking an appropriate adapter  32  which will screw onto the ball valve  30  of  FIG. 1 , with the body  34  screwing onto the adapter  32 . The body  34  includes seals on its inner diameter, which may be o-rings or other appropriate rotating seals, so that shaft  36  may be positioned through and sealed with respect to the body  34  as shown. Hole saw  44  is screwed onto one of threaded regions  40  and  42  on the end of shaft  36 , and pilot drill  46  is locked into the end of the shaft  36  by set screw  50  acting against the flat  48  along that end of the pilot drill. With the assembly in place and the ball valve open, the operator, shown in  FIG. 1 , will feed the shaft  36  through the body  34  and adapter  32  so that the hole saw  44  and pilot drill  46  extend through the open ball valve and, with the drill running, will drill a hole in the main. 
     The operation of the pilot drill  46  is illustrated in  FIGS. 5 and 6 . The pilot drill  46  will penetrate the wall of the main  24  before the hole saw  44  does. This has the advantage of first providing a limited area for fluid communication between the pressurized fluid in the main  24  and the internal volume of the SIMTAP and ball valve assembly, allowing pressures to equalize before the hole saw completes the cutting of the larger hole in the main  24 . When the pilot drill  46  penetrates the main  24 , centrifugal force on side regions  60  of the wire through the end of the pilot drill  46  causes the wire ends to sling outward as shown in  FIGS. 5 and 6 , serving as a coupon retaining finger or arms. In this position, coupon  62 , once cut free of the main  24 , cannot fall into the main, as it cannot slide past the side regions  60  of wire  58 , the wire being limited in further rotation by abutment with ends  56  ( FIG. 4 ) of the flats  54  adjacent the end of the drill. In the preferred embodiment, the hardened inserts form the stop. Consequently, coupon  62  is positively retained with respect to the pilot drill  46  and will always be removed from the main  24  and retracted through the ball valve as shaft  36  is withdrawn to its outermost position. In that regard, while the hand drill can be left running during this withdrawal, it has been found that the coupon is always retained, even if the hand drill is shut off during the withdrawal, thereby preventing the coupon from falling into the main  24 , or for that matter into the ball valve, which would also cause problems. 
     The preferred embodiment of the present invention has been disclosed and described with respect to its use with respect to a SIMTAP drilling machine for hot tapping mains, though the pilot drill of the present invention may be readily used with other hot tapping machines, or in other drilling apparatus or other applications where coupon retention is preferred or required, as desired. Similarly, the coupon retention mechanism may take other forms than the simple bent wire of the preferred embodiment. By way of example, in place of the relatively rigid wire member  58  of the preferred embodiment, some form of spring actuated member or members could be used which would elastically fit within the hole formed by the pilot drill  46 , though spring outward once through the hole to prevent the coupon  62  from falling off the end of the pilot drill  46 . For instance, wire member  58  may readily be sized to provide such a spring action by its own elasticity, the same being dimensioned so as to have a free state distance between tips of side regions  60  intentionally greater than the diameter of the hole drilled by the pilot drill  46 . These and other positive coupon retainers, either operative by gravity or centrifugal force, or spring loaded, are within the present invention, though the simple, relatively rigid wire of the preferred embodiment is in fact preferred because of its simplicity, its ruggedness and because it has been found to positively retain the coupon each and every time. Similarly, a conventional drill, such as a tool steel drill without carbide inserts could be used as desired, particularly for drilling into plastic mains. Thus while various embodiments of the present invention have been described herein, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.