Patent ID: 8807886
Filing Date: 2014-08-19
Classification: B23B,Y10T

Abstract:
1. A hole cutter comprising: a blade cylinder having a circular cross section, the blade cylinder having a rotation axis and a distal end; and at least one first blade portion and at least one second blade portion located at the distal end of the blade cylinder, the first and second blade portions are arranged along the rotation direction at intervals; each of the first and second blade portions including: an inside blade formed at a closer position to the rotation axis; an outside blade formed at a farther position from the rotation axis than the inside blade, the outside blade being displaced in the rotation direction relative to the inside blade; and a stepped cutting edge connecting the outside blade and the inside blade to each other, wherein each of the outside blade and the inside blade has one cutting edge that extends along a radial direction or a plurality of cutting edges that extend along the radial direction and are displaced from each other in the rotation direction, wherein, in the first and second blade portions that are adjacent to each other along the rotation direction, the sum of the number of cutting edges of the outside blade and the inside blade of the first blade portion is three or more, the sum of cutting edges of the outside blade and the second blade portion is two or more, the number of the cutting edges of the first blade being different from the number of the cutting edges of the second blade portion, and wherein an odd number of the first blade portions and an even number of the second blade portions are arranged along the rotation direction, and the arrangement of the first and second blade portions includes a part in which two of the first blade portions or two of the second blade portions are arranged adjacent to each other.