Anti-burr fastener
A fastener includes a cylindrical shaft located between a head and a tapered point, threads integrally extending from the shaft and extending along a portion of a length thereof, and a burr cutoff area near the tapered point and including flank surfaces therein forming an angle greater than 90° therebetween. A flattened area can be located between the flank surfaces.
1. A fastener comprising:
a shaft, a head located at a first end of the shaft, and a tapered point located at an opposite end of the shaft;
threads integrally extending from the shaft and extending along a portion of a length thereof; and
a burr cutoff area formed in the shaft adjacent to the tapered point, the burr cutoff area including flank surfaces forming an angle α of greater than 90° therebetween; and
a flattened area located between the flank surfaces.
2. The fastener of claim 1 , wherein α is from at least 90° to 145°.
3. The fastener of claim 1 , further comprising a sealing washer located on the shaft under the head.
4. The fastener of claim 1 , wherein the flank surfaces are arranged at an angle of α/2 from a center line that extends radially from the shaft through a center of the cutoff area.
5. A fastener comprising:
a shaft, a head located at a first end of the shaft, and a tapered point located at an opposite end of the shaft;
threads integrally extending from the shaft and extending along a portion of a length thereof;
a burr cutoff area formed in the shaft adjacent to the tapered point, the burr cutoff area including flank surfaces forming an angle α of greater than 90° therebetween; and
a first one of the flank surfaces is arranged at an angle α 1 of about 90° from a radial line extending from the shaft through a bottom of the burr cutoff area, and a second one of the flank surfaces is arranged at an angle α 2 of about 5° to 50° from the radial line.
6. The fastener of claim 5 , wherein the angle α 2 is about 45°.
7. A fastener of claim 5 , wherein the second one of the flank surfaces faces in an advancing direction of the thread.
8. A method of forming an anti-burr-forming fastener comprising:
providing a rotating cutting tool with a cutting surface including, in cross-section, two sides set at an angle of greater than 90° to each other that are connected by a flat portion;
applying the cutting surface to a screw in an area adjacent to a tip of the screw, cutting a groove generally parallel to an axis of the screw forming a cutoff area with two flank surfaces at an angle of greater than 90° to each other connected by a flattened area.
9. The method of claim 8 , wherein the two sides are arranged at equal angles to the flat portion.
10. A method of forming an anti-burr-forming fastener comprising:
providing a rotating cutting tool with a cutting surface including, in cross-section, two sides set at an angle of greater than 90° to each other,
applying the cutting surface to a screw in an area adjacent to a tip of the screw, cutting a groove generally parallel to an axis of the screw forming a cutoff area with two flank surfaces at an angle of greater than 90°, with one of the two sides being arranged at an angle α 1 of about 90° to a radial line extending from the shaft through a bottom of the groove, and a second one of the two sides is arranged at an angle α 2 of about 5° to 50° from the radial line.