Abstract: Large diameter edges formed in arc shapes having curvature radii larger than a ball radius are provided. This allows improving surface roughness of a machined surface by cutting of a planar surface with the respective large diameter edges compared with cutting of a planar surface with a ball end cutting edge formed in an arc shape having a single curvature radius. Further, since the respective large diameter edges are formed in the arc shape, compared with cutting of a curved surface with linear cutting edges, surface roughness of a machined surface can be improved by cutting a curved surface with the respective large diameter edges. Accordingly, a pick feed during the cutting of the planar surface and the curved surface with the respective large diameter edges can be increased, and therefore machining efficiency in the cutting of both of the planar surface and the curved surface can be improved.

Abstract: Large diameter edges formed in arc shapes having curvature radii larger than a ball radius are provided. This allows improving surface roughness of a machined surface by cutting of a planar surface with the respective large diameter edges compared with cutting of a planar surface with a ball end cutting edge formed in an arc shape having a single curvature radius. Further, since the respective large diameter edges are formed in the arc shape, compared with cutting of a curved surface with linear cutting edges, surface roughness of a machined surface can be improved by cutting a curved surface with the respective large diameter edges. Accordingly, a pick feed during the cutting of the planar surface and the curved surface with the respective large diameter edges can be increased, and therefore machining efficiency in the cutting of both of the planar surface and the curved surface can be improved.

Abstract: A rotary cutting tool includes: a blade portion; a shank portion having a diameter larger than a diameter of the blade portion; and a tapered connecting portion connecting the blade portion and the shank portion. The shank portion includes a plurality of coolant-guide recessed grooves provided in its outer circumferential surface. Each of the coolant-guide recessed grooves has a groove depth and a groove width that is larger than the groove depth. Each of the coolant-guide recessed grooves has a groove bottom that is shaped such that the groove depth is reduced as the each of the coolant-guide recessed grooves extends from its start end toward a groove-depth regional-change position in which a tendency of change of the groove depth is changed.

Abstract: A hard coating includes first and second layers. The first layer is constituted by AlaCrb?cN, wherein atomic ratios a, b, c satisfy a+b+c=1, 0?c?0.40 and 0.25?b/a?1.0, and an optional additive component ? is at least one kind of element selected from groups IVa, Va and VIa (except Cr) and Y of periodic table of elements. The second layer is constituted by AldCreCfN, wherein atomic ratios d, e, f satisfy d+e+f=1, 0.001?f?0.20 and 0.25? e/d?1.0. A total thickness T of a thickness T1 of the first layer and a thickness T2 of the second layer is 0.5-9.0 ?m. A ratio of the thickness T2 to the total thickness T is 5-50%. The hard coating has peaks belonging to (111) and (200) planes in an X-ray diffraction, such that an intensity ratio of a peak intensity SP1 of the (111) plane to a peak intensity SP2 of the (200) plane is 0.1-20.

Abstract: Large diameter edges formed in arc shapes having curvature radii larger than a ball radius are provided. This allows improving surface roughness of a machined surface by cutting of a planar surface with the respective large diameter edges compared with cutting of a planar surface with a ball end cutting edge formed in an arc shape having a single curvature radius. Further, since the respective large diameter edges are formed in the arc shape, compared with cutting of a curved surface with linear cutting edges, surface roughness of a machined surface can be improved by cutting a curved surface with the respective large diameter edges. Accordingly, a pick feed during the cutting of the planar surface and the curved surface with the respective large diameter edges can be increased, and therefore machining efficiency in the cutting of both of the planar surface and the curved surface can be improved.

Abstract: A thread forming tap including a complete thread portion and a leading portion is to be screwed into a prepared hole provided in a workpiece so as to cause an inner circumferential surface of the prepared hole to be plastically deformed for thereby forming an internal thread corresponding to the external thread provided in the complete thread portion. A screw thread of the external thread has a leading flank and a trailing flank, which are to be positioned on a front side of the trailing flank and on a rear side of the leading flank, respectively, when the thread forming tap is screwed into the prepared hole. The screw thread is shaped such that, in the leading portion, an indentation depth into the workpiece made by the leading flank is smaller than an indentation depth into the workpiece made by the trailing flank.

Abstract: Provided is a rolling die that increases the durability of a nitrided molded surface. The rolling die (1) includes a tool base material that is made of steel and has a molded surface (2) on which a plurality of working teeth (10) is formed. The tool base material includes a nitride layer (15) in which nitrogen is diffused. The nitride layer (15) is disposed to reach a position that is 20 to 70 ?m in depth from the molded surface (2). The molded surface (2) has a surface hardness of at least 1100 HV. The rate of depth change from the depth (D1) of the nitride layer (15) at crests (11) of the working teeth (10) to the depth (D2) of the nitride layer (15) at roots (13) of the working teeth (10) is not higher than 30%.

Abstract: A thread forming tap including a complete thread portion and a leading portion that are provided with an external thread. A thread ridge of the external thread has, in an axial cross section, a triangular shape that is defined by a pair of flanks located on respective opposite sides in an axial direction, such that each of the flanks is inclined by a predetermined flank angle corresponding to a shape of a valley of an internal thread to be formed. A sharp crest is provided in a top portion of the thread ridge at least in the leading portion, and has, in the axial cross section, a triangular shape that is defined by a pair of side surfaces located on respective opposite sides in the axial direction, such that each of the side surfaces is inclined by an inclination angle that is larger than the flank angle.

Abstract: A diamond smoothing method of irradiating a laser light onto a raised and recessed surface of a diamond, so as to smooth the raised and recessed surface, by ablation that is caused to occur in the diamond by irradiation of the laser light onto the raised and recessed surface. The method includes: a threshold-energy-density detecting step of irradiating the laser light onto the raised and recessed surface, and changing an irradiation energy density of the laser light, so as to detect a threshold energy density as a lower threshold value of the irradiation energy density that causes the ablation to occur; and a smoothing processing step of executing a smoothing processing by irradiating the laser light onto the raised and recessed surface with a smoothing irradiation energy density that is set to be within a range from 1 to 15 times as large as the threshold energy density.

Abstract: An end mill that facilitates discharge of chips and enables twining of chips to be suppressed is provided. An end mill (10) includes a tool body, a helical flute, an end cutting edge, a flank, and a gash. The gash forms a cutting face of the end cutting edge. The cutting face is formed as a recessed curved surface and the end cutting edge comprised of a ridge between the cutting face and the flank is concavely curved.

Abstract: A method of producing a nitrided cut tap that includes a nitrogen diffusion layer. The method includes (a) a nitriding step for forming the nitrogen diffusion layer in which nitrogen atoms contained in an atmospheric gas are diffused from a surface of a base material of the cut tap under heat, such that the nitrogen diffusion layer has a thickness ranging from 10 ?m to 30 ?m; and (b) a honing step for rounding a cutting edge portion by colliding abrasive particles against a local part of the cutting edge portion of the base material of the cut tap that has been subjected to the nitriding step, such that a difference between a thickness of the nitrogen diffusion layer in the cutting edge portion and a thickness of the nitrogen diffusion layer in flank and rake surfaces sandwiching the cutting edge portion, is not larger than 5 ?m.

Abstract: An end mill includes a plurality of peripheral cutting edges having a cutting diameter that is constant over their entire cutting length. The plurality of peripheral cutting edges, which are adjacent to each other, are defined by curved teeth. Each of the curved teeth is twisted in a twist direction that is changed irreversibly and smoothly from one of rightward and leftward directions to the other of the rightward and leftward directions in the entire cutting length so as to be reversed right and left on its way. Each of the curved teeth has a curved shape curved in an arcuate or arched manner in a development view of an outer circumferential surface of the end mill around an axis such that a corresponding one of the peripheral cutting edges is provided on a concave side of the curved shape.

Abstract: A three-flute drill includes a body, discharge grooves, cutting edges, thinning edges and gash portions. The discharge grooves are provided in an outer peripheral surface of the body. The cutting edges are provided on ridge sections between inner faces of the discharge grooves and flanks of the body. The thinning edge extends from an end of the cutting edge toward a radially inner side. The gash portion includes an R portion and a straight portion. A first ridge line between the R portion and the flank extends while curving toward a rotation direction, from an end of the thinning edge toward a radially outer side. A second ridge line between the straight portion and the flank extends linearly from an end of the first ridge line toward the radially outer side, and connects to the discharge groove further to the radially inner side than the outer peripheral surface.

Abstract: An end mill includes a plurality of peripheral cutting edges that are defined by three types of teeth including a right-handed helical tooth that is twisted rightward, a left-handed helical tooth that is twisted leftward, and a curved tooth which is twisted in a direction reversed right and left on a way thereof and which has a curved shape curved in an arcuate or arched manner in a development view of an outer circumferential surface of the end mill around an axis such that a corresponding one of the peripheral cutting edges is provided on a concave side of the curved shape. Each adjacent pair of the peripheral cutting edges adjacent to each other are defined by the respective teeth that are different in type from each other.

Abstract: An end mill includes a plurality of peripheral cutting edges have respective helix angles which are equal to each other and which range from 0° to 5°. Each of the plurality of peripheral cutting edges is defined by one of four types of teeth A-D consisting of (a) teeth A-C each defining a partially-uneven cutting edge that includes an uneven edge portion consisting of a nicked portion or a roughing portion and (b) a tooth D that does not define the uneven edge portion. The peripheral cutting edges are defined by at least two of the four types of teeth A-D, such that each adjacent pair of the peripheral cutting edges adjacent to each other are defined by the teeth that are different in type from each other.

Abstract: A ballscrew thread forming tap including a complete thread portion and a leading portion is to be screwed into a prepared hole provided in a workpiece so as to cause an inner circumferential surface of the prepared hole to be plastically deformed for thereby forming a ballscrew thread corresponding to an external thread provided in the complete thread portion. A screw thread of the external thread has a leading flank and a trailing flank, which are to be positioned on a front side of the trailing flank and on a rear side of the leading flank, respectively, when the ballscrew thread forming tap is screwed into the prepared hole. The screw thread is formed such that, in the leading portion, an indentation depth into the workpiece made by the leading flank is smaller than an indentation depth into the workpiece made by the trailing flank.

Abstract: Provided is a rolling die that increases the durability of a nitrided molded surface. The rolling die (1) includes a tool base material that is made of steel and has a molded surface (2) on which a plurality of working teeth (10) is formed. The tool base material includes a nitride layer (15) in which nitrogen is diffused. The nitride layer (15) is disposed to reach a position that is 20 to 70 ?m in depth from the molded surface (2). The molded surface (2) has a surface hardness of at least 1100 HV. The rate of depth change from the depth (D1) of the nitride layer (15) at crests (11) of the working teeth (10) to the depth (D2) of the nitride layer (15) at roots (13) of the working teeth (10) is not higher than 30%.

Abstract: A ballscrew thread forming tap including a complete thread portion and a leading portion is to be screwed into a prepared hole provided in a workpiece so as to cause an inner circumferential surface of the prepared hole to be plastically deformed for thereby forming a ballscrew thread corresponding to an external thread provided in the complete thread portion. A screw thread of the external thread has a leading flank and a trailing flank, which are to be positioned on a front side of the trailing flank and on a rear side of the leading flank, respectively, when the ballscrew thread forming tap is screwed into the prepared hole. The screw thread is formed such that, in the leading portion, an indentation depth into the workpiece made by the leading flank is smaller than an indentation depth into the workpiece made by the trailing flank.

Abstract: A tapered end mill includes an outer circumferential cutting edge, a flute is disposed such that a flute bottom radius defined as a distance between a flute bottom and the tool axis decreases from a shank side toward the tool tip side, the flute bottom radius linearly changes at a predetermined gradient angle in the tool axis direction, the gradient angle changes at a predetermined change point to become smaller on the tool tip side as compared to the shank side, and a gradient angle ?1 on the tool tip side relative to the change point is equal to or larger than 0° and smaller than a taper half angle ? of a cutting portion provided with the outer circumferential cutting edge, and a gradient angle ?2 on the shank side relative to the change point is larger than the taper half angle ?.

Abstract: A method for chamfering toothed gears which enables lengthening of a life of a tool is provided. The chamfering method is for sequentially chamfering the line intersection portions 23 between tooth flanks 21 and end faces 22 of teeth 2 with end cutting edges 122. A pitch Pb of the end cutting edges 122 is set to five times a pitch Fa of the teeth 2. As a result, at a chamfering step of chamfering line intersection portions 23 of the teeth 2, a circumferential speed of the end cutting edges 122 can be made faster than a circumferential speed of the teeth 2. Consequently, a difference in circumferential speed between the end cutting edges 122 and the teeth 2 can be utilized in chamfering and thus a cutting resistance can be reduced during the chamfering. Therefore, a life of the tool 100 can be lengthened.