Patents Assigned to Kabushiki Kaisha Mayanaga
  • Patent number: 9162371
    Abstract: An object is to provide a drill bit with improved strength of joint between a bit tip and a bit shaft without diminishing dust suction performance of the drill bit. A drill bit 1 includes: a bit tip 3 including at least three cutting edge portions arranged at the distal end of the bit tip 3 such that they are spaced apart from each other in a circumferential direction, each cutting edge portion 3c having a rake face 3s and a relief face 3e forming a joint ridge L1 serving as a cutting edge; and a bit shaft 2 having a distal end face 2F welded to a proximal end face of the bit tip 3 such that the bit shaft 2 rotates integrally with the bit tip 3. The bit shaft 2 includes a dust suction passage 4 extending in the longitudinal direction of the bit shaft 2, such that the distal end of the dust suction passage 4 extends to a distal end portion of the bit shaft.
    Type: Grant
    Filed: April 19, 2011
    Date of Patent: October 20, 2015
    Assignee: Kabushiki Kaisha Mayanaga
    Inventor: Masaaki Miyanaga