Abstract: A ball end mill comprises a gash provided at a front end portion of a main end mill body rotated about an axis; and at least one cutting edge which has a rotational trajectory around the axis that forms a convex hemispherical shape having a center on the axis. The cutting edge is formed at a peripheral edge portion of a wall surface of the gash. A difference between a first and second included angles is within ±7°, where the first included angle is formed between the axis and a straight line connecting the center with a cutting edge position at which a depth of the gash is maximal in a cross-section orthogonal to the cutting edge, and the second included angle is formed between the axis and a straight line connecting the center with a cutting edge position at which a rake angle of the cutting edge is maximal.

Abstract: Even if chips enter a gap between a flank face and a surface to be worked, the defect of the flank face or a cutting edge is suppressed by the control of the flow of the chips. A plurality of cutting edges, which are undulated in wave forms in a direction of an axis, are formed on an outer periphery of a front end portion of an end mill body rotating about the axis so that phases of the wave forms are displaced from each other in a path of rotation about the axis; flank faces of the cutting edges are covered with a coating film; and rough surface regions and smooth surface regions are alternately formed on the surface of at least portions of the coating film, which are close to the cutting edges, in the direction of the axis.

Abstract: Even if chips enter a gap between a flank face and a surface to be worked, the defect of the flank face or a cutting edge is suppressed by the control of the flow of the chips. A plurality of cutting edges, which are undulated in wave forms in a direction of an axis, are formed on an outer periphery of a front end portion of an end mill body rotating about the axis so that phases of the wave forms are displaced from each other in a path of rotation about the axis; flank faces of the cutting edges are covered with a coating film; and rough surface regions and smooth surface regions are alternately formed on the surface of at least portions of the coating film, which are close to the cutting edges, in the direction of the axis.

Abstract: A ball end mill comprises a gash provided at a front end portion of a main end mill body rotated about an axis; and at least one cutting edge which has a rotational trajectory around the axis that forms a convex hemispherical shape having a center on the axis. The cutting edge is formed at a peripheral edge portion of a wall surface of the gash. A difference between a first and second included angles is within ±7°, where the first included angle is formed between the axis and a straight line connecting the center with a cutting edge position at which a depth of the gash is maximal in a cross-section orthogonal to the cutting edge, and the second included angle is formed between the axis and a straight line connecting the center with a cutting edge position at which a rake angle of the cutting edge is maximal.

Abstract: An end mill comprises: a main body with two coolant holes; three chip discharge grooves formed at an outer periphery of a tip portion of the main body; gashes formed at the tip portions of the three chip discharge grooves; and three end cutting edges formed at intersecting ridgeline portions between tip flanks and wall surfaces facing an end mill rotation direction of the gashes. One end cutting edge is long and extends across the axis line at a tip of the main body. Inner peripheral ends of two remaining end cutting edges are disposed at intervals from the axis line. Two coolant holes are drilled toward a tip side in a direction of the axis line. A first coolant hole opens at the tip flank of the long edge, and a second coolant hole opens at a gash of one of the two remaining end cutting edges.

Abstract: The present invention provides a member coated with a hard coating and to attain excellent wear resistance. The hard coating includes: an adhesion reinforcing layer formed on a surface of the member; and a second layer formed on the adhesion reinforcing layer and having a composition represented by the following formula: (AlpTiqVr)(NuCv) where 0≦p≦0.75, 0.20≦q≦0.75, 0.10≦r≦0.75, p+q+r=1, 0.6≦u≦1, and u+v=1. In order to further enhance the adhesion of the hard coating to the member, an intermediate layer may be formed between the first and second layers.