Twist Drill Patents (Class 76/108.6)
  • Patent number: 6190097
    Abstract: Significantly improved resistance to breaking while drilling in metal can be realized in twist drill bits having a web thickness taper which is about twice the web thickness taper specified in Standards and in common use in the industry. This creates much shallower flutes and flies in the face of conventional wisdom in the art which holds that the web taper rate should be low to maximize the amount of flute volume available to convey chips and sawdust out of the hole. A flute length of about 1/2″ less than the flute lengths specified by the Standards makes it possible to have such a large taper rate but still control variations in tolerances for the flute length. It also provides a marking zone for placing size indicia on the drill bit shank outside the portion which is gripped by the chuck jaws of a power drill.
    Type: Grant
    Filed: March 6, 2000
    Date of Patent: February 20, 2001
    Assignee: Black & Decker Inc.
    Inventor: Rickey J. Thomas