Patent Application
20200108451
The present disclosure relates to drill bits.
Drill bits are generally used with power tools such as rotary drills or hammer-type drills to cut or carve holes into a material or surface. Drill bits are used to cut holes into a variety of materials such as brick, block, tile, metal, marble, concrete, plaster, wood, plastic, dry-wall, etc., or any combination thereof. Drill bits need to be versatile, but also need to be durable to withstand drilling in abrasive materials.
In one embodiment, the disclosure provides a drill bit including a body having a first end, a second end opposite the first end, and an axis of rotation extending centrally through the body from the first end to the second end. The drill bit also includes a shank adjacent the second end. The shank is configured to couple to a tool. The drill bit further includes a cutting head adjacent the first end. The cutting head includes a pilot tip and a cutting portion. The cutting portion has first tip surfaces and second tip surfaces on opposite sides of the pilot tip. Each first tip surface extends radially outward from the pilot tip to a corresponding second tip surface. Each second tip surface extends from a corresponding first tip surface to an outer periphery of the body. The first tip surfaces define a first tip angle through the axis of rotation that is less than 180 degrees. The second tip surfaces define a second tip angle through the axis of rotation that is smaller than the first tip angle.
In another embodiment, the disclosure provides a method of manufacturing a drill bit. The method includes providing a piece of bar stock having a first end, a second end opposite the first end, and an axis of rotation extending centrally through the bar stock between the first and second ends. The method also includes cutting the first end of the bar stock to form a cone having a second tip angle measured through the axis of rotation, and further cutting the cone at the first end of the bar stock to form a pilot tip, first tip surfaces, and second tip surfaces. Each set of first and second tip surfaces is positioned on opposite sides of the pilot tip. The first tip surfaces define a first tip angle through the axis of rotation that is less than 180 degrees. The second tip surfaces define a second tip angle through the axis of rotation that is smaller than the first tip angle. The method further includes forming a flute in the bar stock between the first and second ends, and forming a shank at the second end of the bar stock. Optionally, further cutting the cone includes further cutting the cone to form the pilot tip with a tip and an outer periphery surface, the outer periphery surface tapering from the tip toward the axis of rotation to provide a radial relief surface. Optionally, further cutting the cone includes further cutting the cone to form the pilot tip with a tip and an outer periphery surface, the outer periphery surface tapering from the tip toward the axis of rotation to provide a radial relief surface. The method may further include coating the bar stock in a physical vapor deposition, or coating the bar stock in a rust preventative coating, or both. Forming the shank may include forming a hex shank.
Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.
With reference to
With continued reference to
In the illustrated embodiment, the drill bit 10 includes two flutes 30. In other embodiments, the drill bit 10 may include fewer or more flutes 30. The flutes 30 are helically wrapped around the body 14 of the drill bit 10 and extend from the first end 18 of the body 14 to the shank 34. Preferably, the flutes 30 extend at least half the length of the body 14. Even more preferably, the flutes 30 have a length 1 between 23 mm and 100 mm. The flutes 30 are helically wrapped around the body 14 at a variable helix angle. In other words, the angle at which the flutes 30 wrap about the body 14 change as the flutes 30 extend from the first end 18 to the shank 34. In the illustrated embodiment, a helix angle W1 of each flute 30 adjacent the first end 18 is larger than a helix angle W2 of each flute 30 adjacent the shank 34. Preferably, the helix angle W1 of each flute 30 adjacent the first end 18 is approximately 35 degrees, and the helix angle W2 of each flute 30 adjacent the shank 34 is between 15 degrees and 20 degrees. In some embodiments, the helix angles of the flutes 30 may gradually transition from the first helix angle W1 to the second helix angle W2. In further embodiments, the flutes 30 may have a constant helix angle.
With reference to
As shown in
With reference to
The first tip surface 56 extends from the outer periphery surface 48 of the pilot tip 44 to the second tip surface 58, and the second tip surface 58 extends from the first tip surface 56 to the outer periphery of the body 14 of the drill bit 10. In other words, the first tip surface 56 extends away from the outer periphery surface 48 of the pilot tip 44 a distance, at which point the cutting portion 46 is further chamfered to the second tip surface 58. The second tip surface 58 extends from the ends of the first tip surface 56 to the ends of the diameter D1 of the body 14 of the drill bit 10.
The first tip surfaces 56 define a first tip angle η1 measured through the axis of rotation 26. The first tip angle η1 is an oblique angle. More particularly, the first tip angle η1 is less than 180 degrees such that the first tip surfaces 56 are not parallel. The first tip angle η1 may be within a range between 150 degrees and 180 degrees. In some embodiments, the first tip angle η1 is within a range between 155 degrees and 165 degrees. In further embodiments, the first tip angle η1 is 160 degrees.
The second tip surfaces 58 define a second tip angle η2 measured through the axis of rotation 26. The second tip angle η2 is smaller than the first tip angle η1. For example, the second tip angle η2 may be between 10% and 35% smaller than the first tip angle η1. In some embodiments, the second tip angle η2 may be about 15% smaller than the first tip angle η1. The second tip angle η2 may be within a range between 120 degrees and 150 degrees. In some embodiments, the second tip angle η2 may be within a range between 130 degrees and 140 degrees. In further embodiments, the second tip angle η2 is 135 degrees.
To manufacture the drill bit 10, a cylindrical bar stock rod of metal, preferably a durable steel alloy, is provided. First, the first end 18 is transformed into a gently sloping cone-shaped tip. To accomplish this, a machine (e.g., a computer numerical control machine) rotates the drill bit 10 rapidly about the axis of rotation 26 while a first machining tool cuts (e.g., grinds) the first end 18 of the rod at an angle forming a cone. Specifically, the first end 18 is cut to produce the second tip surfaces 58 at the second tip angle η2 prior to forming the first tip surfaces 56. Next, a second machining tool cuts (e.g., grinds) a portion of the cone or second tip surfaces 58 while the drill bit 10 is rotated. In particular, the second machining tool cuts the cone of the rod at an oblique angle relative to the axis of rotation 26 to form the first tip surfaces 56 at the first tip angle η1 which separates the pilot tip 44 from the second tip surfaces 58.
The machine stops spinning the drill bit 10 and moves it into position for cutting the flutes 30. A third machining tool is then angled obliquely relative to the drill bit 10. The third machining tool moves parallel to the axis of rotation 26 from the first end 18 to the second end 22 while the machine slowly rotates the drill bit 10 forming the helical flutes 30. Finally, the second end 22 of the drill bit 10 is grinded down by a fourth machining tool to form the hex shaped shank 34. In some embodiments, the flutes 30 and shank 34 may be formed prior to forming the tip surfaces 56, 58. In other, embodiments, the drill bit 10 may further be cut or grinded to form cutting edges, cutting tips, or other tip surfaces. In further embodiments, the machining tools may all be the same tool or all different tools. Additionally, the same machining tool may be used more than once.
Alternatively, in some embodiments, the first tip angle η1 and the second tip angle η2 may be formed at different magnitudes by separately grinding the tip surfaces 56, 58. For example, the cutting head 42 of the drill bit 10 may first be ground to form the second tip angle η2, and then the drill bit 10 may be further ground to form the first tip angle η1.
Providing the first tip surfaces 56 at a non-orthogonal angle relative to the axis of rotation 26 increases the cutting speed of the drill bit 10. In addition, providing a web K that tapers from the second end 22 to the first end 18 increases the durability of the drill bit 10.
In some embodiments, the drill bit 10 may be coated with a rust preventive coating that is applied to the entire drill bit 10 such as black oxide. In further embodiments, the drill bit 10 may be coated with a PVD (physical vapor deposition) coating, such as titanium-nitride coating.
Various features and advantages of the disclosure are set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201821636987.6 | Oct 2018 | CN | national |
