Patent Publication Number: US-6981911-B2

Title: Abrasive drill bit

Description:
RELATED APPLICATION 
   This application is a continuation of application Ser. No. 09/817,648, filed Mar. 26, 2001 now abandoned , the disclosure of which is incorporated herein in its entirety by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a method and system for drilling holes in ceramic and glass material. Specifically, the invention describes an abrasive drill bit that produces a smooth hole in ceramic and glass without cracking or chipping the ceramic. 
   It is understood that the terms “ceramic”, “tile”, “glass”, “stone” and like terms are used interchangeably as relating to this invention, which works well when drilling holes in all such similar materials. Likewise, these terms are used interchangeably when describing prior art, unless otherwise noted. 
   2. Related Art 
   There are presently two main methods of making a hole in tile: breaking and drilling. 
   Breaking has been the method of choice in construction, especially in plumbing installation and repair. To access plumbing, a hole is created by breaking through the tile with a small hammer and/or chisel. The best results of this method are a jagged hole; the worst results are a cracked or shattered tile that must be replaced. This technique always requires some type of cover to cover the jagged edges of the hole and to provide an air block around the hole, since a tight seal around the plumbing is difficult if not impossible. The breaking technique is not possible when dealing with crystalline structures such as glass and many crystalline stones, which will simply shatter if struck with a chisel of similar tool. 
   Drilling a hole into glass and tile has been possible using a diamond or carbide tipped drill bit  100 , also referred to as a “tungsten arrow”, such as seen in  FIG. 1A  (prior art). The carbide tip  110  of carbide drill bit  100  is typically a diamond-lapped or tungsten tip that is spear shaped and able to drill through the glass. The user of carbide tipped drill bit  100  must carefully align and brace the drill that is turning the bit through the use of a special jig. This jig ensures proper alignment of the tip for drilling through the glass and with adequate pressure. Thus, drilling with carbide tipped drill bit  100  is not feasible in the field, due to this required special equipment and orientation. Another limitation of this drill bit is its expense. Another limitation is its small diameter, as standard sized carbide tipped drill bits are less than ½″ in diameter. Additionally, the finished hole produced with carbide tipped drill bit  100  usually has sharp edges, which must be smoothed off with an emery cloth or other tool, posing a cutting hazard during the smoothing off process. 
   To drill larger holes, such as over 1″ in diameter, in ceramic and glass material, the typical modem method in the prior art uses a diamond coated box drill bit  120 , as shown in FIG B (prior art). Segment tips  125  are coated with diamond, and can cut through glass when properly aligned with a press drill. Box drill  120  must be continuously cooled during use, typically with antifreeze or other liquid capable of removing the high amounts of heat produced. Failure to do so may result in cracking of the glass and/or damage to the bit, which is expensive. While this method may be useful in a shop, such as that of a lamp maker, glass worker and the like who must drill holes in ceramic for wiring, switches, etc., it is not feasible in plumbing operations, due to the required alignment jib, mess of the coolant, etc. 
   It would therefore be useful improvement of the prior art for a device and method to drill holes, including large diameter (greater than 1″) holes, in glass, ceramics, tile and like materials, using a standard electric drill without a cumbersome jig. 
   BRIEF SUMMARY OF THE INVENTION 
   Accordingly, the objectives of this invention are to provide, inter alia, a new and improved device and method of forming a hole in glass, tile, ceramics and similar materials that is capable of: 
   using a bit that can be used in a standard electric drill; 
   not requiring special lubricants; 
   being used on the jobsite away from the user&#39;s shop or plant; 
   forming a smooth hole that does not need to be polished after drilling; and 
   being cost efficient. 
   These objectives are addressed by the structure and use of the inventive abrasive drill bit. The device typically chucks to a standard electric hand-held drill. The bit is a cylinder with a sponge type material or a sweeping rubber flap in its interior. Water and abrasive is mixed in the interior of the guide hole, and optionally additional abrasive and/or water may be added through a top opening in the cylinder when the bit is still. The bit is preferably aligned with a guide, which is placed against the material to be drilled. The abrasive weeps through holes in the sides of the bit cylinder, and the bottom edge of the cylinder traps and presses the abrasive against the glass or similar solid material to grind a cut-out hole in the material. The final hole size is limited only by the diameter of the abrasive cylinder bit, and typically can range from ½″ to over 4″, although other sizes are also practical. The cut-out hole typically has smooth edges without sharp cutting edges along the rim. 
   Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A and 1B  depict prior art drill for glass and ceramics. 
       FIG. 2  depicts a large diameter abrasive drill bit. 
       FIG. 3  depicts a smaller diameter abrasive drill bit. 
       FIG. 4  depicts the interior of the inventive abrasive drill bit. 
       FIG. 5  depicts the inventive drill bit attached to a standard electric drill. 
       FIG. 6  depicts the drilling guide positioned on a piece of glass. 
       FIG. 7  depicts the inventive abrasive system, comprising the drill bit attached to a drill and positioned in the drilling guide on a piece of glass. 
       FIGS. 8A and 8B  depict a preferred embodiment of the drilling guide. 
       FIGS. 9A and 9B  depict an alternate solid grinding bit. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is described abrasive cylinder bit  1 . In the preferred embodiment, abrasive cylinder bit  1  is used in abrasive system  10 , comprising drill  15 , abrasive cylinder bit  1  and guide  9 , as depicted in FIG.  7 . 
   Abrasive cylinder bit  1  is depicted in a larger diameter version in  FIG. 2 , and a smaller diameter version in FIG.  3 . The larger diameter version is typically greater than 2″ in diameter, and the smaller version is typically less than 2″ in diameter. Otherwise, the two bits  1  are structurally the same. 
   Abrasive cylinder bit  1 , as depicted in  FIGS. 2-4 , comprises a connection means to a drill, said connection means typically comprising connection shaft  4 , which is permanently mounted to the center of cylinder base  5  of cylinder  11 . Alternatively, the drill connection means may be a socket hole (not shown) for receiving a socket stem or shaft (not shown), such as found in prior art socket wrenches. Cylinder  11  is preferably made of a hard metal that is resistant to heat and erosion inherent in the grinding/abrasion process. Inlet hole  6  traverses through cylinder base  5 , preferably near the perimeter of cylinder base  5 . In the preferred alternative, cylinder base  5  is interrupted, and comprises one or more base cavities  14 , as depicted in FIG.  3 . In either embodiment, cylinder base  5  attaches to cylinder side  8 , which has cylinder edge  2  distal from cylinder base  5 . Cylinder edge  2  preferably is smooth, having no teeth or other irregular surface. Abrasive slots  3  traverse through cylinder side  8  from cylinder edge  2  toward cylinder base  5 . In the preferred embodiment, abrasive slots  3  extend from cylinder edge  2  to a position ⅓ to ½ up the length of cylinder side  3 . 
   Cylinder  11  has cylinder interior  7 . Oriented within cylinder interior  7  is sweeping material  18  for directing abrasive material toward cylinder edge  2 . In the preferred embodiment, sweeping material  18  may be soft flap  17  as shown in  FIG. 4 , or it may be sponge  16  as depicted in FIG.  5 . Any material capable of moving abrasive material outward as described may be used. 
   Guide  9 , as depicted in  FIG. 6  while positioned on a piece of glass  20 , comprises guide hole  13 , which affords a guide for abrasive cylinder bit  1 . In the preferred embodiment shown in  FIGS. 8A  (top view) and  8 B (side view), guide hole  13  has abrasive material relief reservoir  21 . Abrasive material relief reservoir  21  allows abrasive material slurry to cycle from cylinder interior  7  into abrasive material relief reservoir  21  and back again into cylinder interior  7  and/or abrasive slots  3 . This provides both a more even distribution and coating of the abrasive material on cylinder edge  2 , and also aids in cooling the abrasive material. 
   Alternatively, a hole may be ground in glass  20  using abrasive shaft bit  25 , as depicted in FIG.  9 A. Shown in greater detail in  FIG. 9B , abrasive shaft bit  25  has a grinding surface  27  at its tip. Abrasive shaft bit  25  may be a solid cylindrical shaped shaft, or it may have a cylindrical first end for attaching to drill  15  and a flattened second end comprising grinding surface  27 . In either embodiment, bit point  26  is preferably oriented at the tip of abrasive shaft bit  25  to provide an initial pilot depression in glass  20  about which abrasive shaft bit  25  rotates to grind through glass  20  to form a hole. While there are no absolute range limits on the use of this alternate solid bit, the preferred hole sizes to be ground out are less than 1″. 
   Operation 
     FIG. 7  depicts abrasive system  10 , the preferred embodiment of the use of abrasive bit  1 . Abrasive bit  1  is chucked into drill  15  at connection shaft  4 . Guide  9  is then placed flat on glass  20 , which may be any vitreous material, including glass, tile, and ceramic, as well as concrete, Formica™, natural or synthetic stone or similar material. To minimize breakage, glass  20  is preferably placed on a vibration absorbing material, such as soft wood, carpeting, hard rubber, etc. Alternatively, glass  20  may be tile mounted on a wall, in which case guide  9  is simply held against glass  20 . 
   Abrasive material, such as emery powder, zirconium powder, aluminum oxide mixed with or without titanium, or any other similar abrasive material, is placed into the bottom of guide hole  13  and mixed with a small amount of water, to form a slurry having a consistency thin enough to migrate into abrasive slot  3  while thick enough to have adequate abrasive qualities. Abrasive bit  1  is placed into guide hole  13  such that abrasive bit  1  is flush against glass  20 , preferably with cylinder edge  2  parallel with and connection shaft  4  normal to the surface of glass  20 . Optionally, additional abrasive material may be placed, typically poured or injected, into cylinder interior  7  through inlet hole  6  or base cavity  14 . In an alternative embodiment, the abrasive material is scavenged for re-use using ordinary collection and/or absorption means. 
   Drill  15  is then switched on to turn abrasive bit  1 , preferably at high speed. The abrasive material is ground between cylinder edge  2  and glass  20 , cutting a circle into glass  20 . Abrasive material in cylinder interior  7  is pushed outward towards cylinder edge  2  into abrasive slots  3 . Additionally, abrasive material is pushed under cylinder edge  2  due to the inherent offset between cylinder edge  2  and the surface of glass  20 . This abrasive material is forced towards cylinder edge  2  by the combined centrifugal force of the turning abrasive bit  1  while the abrasive material is “swept” off the surface of glass  20  by sponge  16 , or alternatively soft flap  17 , and directed towards cylinder edge  2 . Where abrasive material relief reservoir  21  is part of guide  9 , the abrasive material migrates from cylinder interior  7  through abrasive slots  3  into abrasive material relief reservoir  21 . The abrasive material in abrasive material relief reservoir  21  also is cycled back through the abrasive slots  3  and under cylinder edge  2  to provide uniform abrasive material to cylinder edge  2 . Additional abrasive material can be added by removing abrasive bit  1  from the partially cut circle and placing additional abrasive material into guide hole  13 , or by injection of the abrasive material into cylinder interior  7  thorough inlet hole  6  or base cavity  14 . 
   The circle extends through glass  20 , creating a punch-out disk of glass  20  that then falls out, or alternatively can be pushed or punched out of cylinder interior  7  by pushing out the side with a rod or similar pusher. 
   Alternatively, in thicker glass, after the circle ground by abrasive bit  1  is preferably approximately ⅔ through glass  20 , guide  9  is repositioned on the opposite side of glass  20  over the circle, assuming glass  20  is transparent or translucent to allow such alignment. A second circle is then ground through glass  20  until it meets up with the first side&#39;s circle. This alternative method allows the abrasive material to flow in and out of abrasive material relief reservoir  21 , since this reservoir is too far above cylinder edge  2  to allow cycle backflow under cylinder edge  2 . 
   It is preferred that abrasive bit  1  periodically be removed from the ground circle during the grinding process and washed with water to allow for periodic cooling and to add additional abrasive material. In this preferred embodiment, the grinding process is suspended periodically, typically every minute, abrasive bit  1  is removed from the cut circle, guide  9  (when used) is removed, and the surface of glass  20  and the partially cut circle washed off with water. This washing removes cuttings form the abrasive/water slurry. As more cuttings become part of the abrasive/water slurry, the abrasive/cutting properties of the slurry decreases since abrasive material becomes a less and less percentage of the slurry, having been “diluted” by the cuttings. After washing out the circle, guide  9  (where used) is replaced, and new abrasive material is placed in guide hold  13  along with a small amount of water, abrasive bit  1  reinserted into the partially cut circle, and grinding resumes. 
   The foregoing method is best performed on a horizontal fixed or secured glass  20 , which again can be any vitreous material or similar hard solid, including but not limited to glass, tile, ceramic, stone, or any hard crystalline material. The method can also be used on non-horizontal surfaces, such as drilling holes in a tile wall for plumbing access. The method is the same, with additional care taken to press or secure guide  9  against the tile, and to ensure sufficient abrasive material is in cylinder interior  7  and/or guide hole  13  for adequate abrasive action in the circle being cut. Typically, the abrasive material is thicker to maintain consistency within cylinder interior  7 . 
   In all embodiments of the grinding method, it is preferred that only light pressure be allowed to press down on cylinder edge  2 . The abrasive material should be allowed to migrate under cylinder edge  2  between cylinder edge  2  and glass  20 . If heavy pressure is applied to abrasive bit  1  and cylinder edge  2 , the abrasive material is pushed out of the interface area between cylinder  1  and cylinder edge  2 , and the abrasive/grinding ability of the abrasive material is lost. 
   While the preferred embodiments described above use guide  9  to align abrasive bit  1  flush against glass  20 , abrasive bit  1  and drill  15  can also be used without guide  9  by carefully aligning cylinder edge  2  flush against the surface of glass  20 . This method is not preferred, since the amount of abrasive material lost is increased due to slinging and leakage of the abrasive material. 
   Use of the alternate abrasive shaft bit  25  is similar to the operation of abrasive cylinder bit  1 . Abrasive material, usually a slurry of abrasive material and water, is placed in guide hole  13 . Abrasive shaft bit  25  is connected at its first end to drill  15 . The second end of abrasive shaft bit  25  comprises grinding surface  27  and bit point  26 . Bit point  26  “digs” or “bites” into glass  20 , to stabilize the position of abrasive shaft bit  25  in the location and normal orientation to glass  20  desired. Drill  15  is energized, rotating abrasive shaft bit  25  and grinding surface  26 . Abrasive material between grinding surface  26  and the surface of glass  20  grinds out a hole in glass  20 . The grinding continues until the hole is through glass  20 . 
   Note that abrasive cylinder bit  1  described above forms a circle that forms a disk that is removed from glass  20 , leaving the hole. Abrasive shaft bit  25  grinds out the entire hole in glass  20 , requiring a greater surface area to be ground compared to that of abrasive cylinder bit  1 . Thus, while either method and device may be used for smaller holes (typically less than 1″ in diameter), abrasive cylinder bit  1  is preferable for holes larger than 1″ in diameter. 
   The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.