Patent ID: 6231275
Filing Date: 2001-05-15
Classification: B23C,Y10T

Abstract:
A ball nose end mill comprising:a holder body that has a tool tip end, extends longitudinally in an axial direction, and includes a first half member and a second half member divided by a slot therebetween at said tool tip end and extending along said axial direction, wherein a first hole is provided through said first half member and a screw head seating surface surrounds said first hole on said first half member, said first half member has a first inner side surface bounding said slot, said second half member has a second inner side surface bounding said slot and facing toward said first inner side surface, and a threaded hole having a female screw threading therein is provided in said second half member;a plate-shaped insert that has front and rear main surfaces with a through hole penetrating through said insert from said front main surface to said rear main surface, and is arranged in said slot with said front and rear main surfaces respectively contacted by said first and second inner side surfaces, wherein said through hole includes a tapered hole as at least a portion of said through hole adjoining said front main surface and tapering to a relatively reduced diameter toward said rear main surface;a clamp screw including a screw shaft that extends through said first hole and said through hole and is thread-engaged in said female screw threading of said threaded hole, and a screw head that is connected to said screw shaft and that bears against said screw head seating surface so as to clamp together said first half member and said second half member with said first and second inner side surfaces pressed against said front and rear main surfaces respectively;a tapered ring that is fitted around said screw shaft, has a tapered surface with a tapered shape corresponding to said tapered hole, and is received in said tapered hole; anda spring that is fitted around said screw shaft between said screw head and said tapered ring and that presses said tapered surface of said tapered ring against said plate-shaped insert in said tapered hole.