Abstract: A superhard sintered body containing cubic boron nitride is bonded to an apical angle part of a tool body having a polygonal shape, and an edge and a chip breaker are formed on the superhard sintered body. A chamfer is formed on the intersection between the upper surface and the side surface of the superhard sintered body, the chip breaker has a protrusion, and an angle ? formed by ridges on the apex of the protrusion or a tangential line at a point bisecting the ridges and a bisector for the apical angle and the ratio of the distance between a first intersection between the two ridges on the apex of the protrusion and an extreme point of the first ridge to the distance between a second intersection between a straight line passing through the first intersection and the extreme point and the outer periphery of the tool body and the first intersection are in prescribed ranges.

Abstract: A superhard sintered body containing cubic boron nitride is bonded to an apical angle part of a tool body having a polygonal shape, and an edge and a chip breaker are formed on the superhard sintered body. A chamfer is formed on the intersection between the upper surface and the side surface of the superhard sintered body, the chip breaker has a protrusion, and an angle ? formed by ridges on the apex of the protrusion or a tangential line at a point bisecting the ridges and a bisector for the apical angle and the ratio of the distance between a first intersection between the two ridges on the apex of the protrusion and an extreme point of the first ridge to the distance between a second intersection between a straight line passing through the first intersection and the extreme point and the outer periphery of the tool body and the first intersection are in prescribed ranges.

Abstract: In a method of making a hard sintered body indexable insert, respective hard sintered bodies used as cutting edges are brazed to seating grooves at corners of the upper and lower surfaces of a tool substrate. A brazing alloy that contains Cu and 0.5 to 65 wt % Ti and/or Zr and inevitable impurities first temporarily bonds and fixes the sintered bodies in the seating grooves by evaporating a solvent component of the brazing alloy. Then, the sintered bodies are brazed and permanently fixed to the tool substrate by heating it in a vacuum or in an inert gas atmosphere. The thickness of the tool substrate remaining between the upper and lower seating grooves is preferably 30% to 90% of the entire thickness of the hard sintered body indexable insert, and the cutting-edge length of the hard sintered body is preferably 0.5 mm to 4 mm.

Abstract: The purpose is to improve the surface roughness Rz of a cut surface to 1.6 &mgr;m or under in cutting e.g. hardened steel. The ball end mill has a cutting blade made of a polycrystalline hard sintered material containing 20 to 95 vol % of cubic boron nitride. The cutting blade has a ridge portion having a radius of curvature of 5 to 30 &mgr;m. A flank and a rake face or a negative land of the cutting blade connect smoothly with the ridge with the radius of curvature. The ridge portion of the cutting blade has a surface roughness of 0.1 to 1.0 &mgr;m in terms of 10-point average roughness (Rz).

Abstract: A cutting edge of a cutting tool is made of a polycrystalline hard sintered material containing at lest 20 vol % of CBN. A radius of curvature in cross section of a ridge of the cutting edge is between 5 &mgr;m and 30 &mgr;m. A flank and a rake face or negative land of the cutting tool are smoothly continued from the radius of curvature in cross section. The surface roughness of the ridge of the cutting edge is from 0.1 &mgr;m to 1.0 &mgr;m as an average roughness (Rz) of a ten point system.

Abstract: A diamond sintered body tool (20) having superior adhesion resistance, chipping resistance and high strength includes a tool base material (22) including a diamond sintered body, and a surface layer (21) formed on a surface of the tool base material (22). The surface layer (21) includes at least one of silicon, a silicon oxide, a silicon carbide, a silicon nitride and a solid solution thereof. The tool base material (22) has an inner portion (22b) including a first content of an iron group metal, and a surface portion (22a) surrounding the inner portion (22b ) and including a second content of the iron group metal lower than the first content.

Abstract: An object of the invention is to provide a hard sintered body indexable insert in which a hard sintered body used as a cutting edge is brazed to all corners of a tool substrate and to seating grooves of the upper and lower surfaces thereof, and which has high performance and is low-cost. A brazing alloy a part of which contains 0.5 to 65 wt % Ti and/or Zr and the remainder of Cu and inevitable impurities is used as a typical brazing alloy, and the hard sintered body is brazed to the tool substrate by heating it in a vacuum or in an inert gas atmosphere. The thickness of the tool substrate between the upper and lower seating grooves is 30% to 90% of the entire thickness of the hard sintered body indexable insert, and the cutting-edge length of the hard sintered body is 0.5 mm to 4 mm.

Abstract: The purpose is to improve the surface roughness Rz of a cut surface to 1.6 &mgr;m or under in cutting e.g. hardened steel. The ball end mill has a cutting blade made of a polycrystalline hard sintered material containing 20 to 95 vol % of cubic boron nitride. The cutting blade has a ridge portion having a radius of curvature of 5 to 30 &mgr;m. A flank and a rake face or a negative land of the cutting blade connect smoothly with the ridge with the radius of curvature. The ridge portion of the cutting blade has a surface roughness of 0.1 to 1.0 &mgr;m in terms of 10-point average roughness (Rz).

Abstract: A diamond sintered body having high wear resistance, chipping resistance, shock resistance and thermal conductivity is provided. The diamond sintered body includes sintered diamond particles and a sintering aid as the remainder. The content of the sintered diamond particles is at least 80% by volume and less than 99% by volume. The sintered diamond particles have a particle size in the range from at least 0.1 &mgr;m to at most 70 &mgr;m. The sintered diamond particles next to each other are directly bonded. The sintering aid includes at least one kind selected from tungsten, iron, cobalt and nickel. The percentage of the tungsten in the sintered body is in the range from at least 0.01% by weight to at most 8% by weight.

Abstract: A tool manufactured by brazing a hard sintered body such as a diamond or cBN to a tool substrate through a bonding layer comprising at least one of Ti and Zr by 15-65 wt % and Cu. Two ridges of the tool substrate on both sides each has a first ridge adjacent to and aligned with a ridge of the hard sintered body and a second ridge provided nearer to an inscribed circle of the tool than is the ridge of the hard sintered body. Also, an upright side face and a bottom of each seating groove formed in the tool substrate intersect each other at an angle smaller than the intersecting angle between a back side and a bottom of each hard sintered body.

Abstract: An improved diamond sintered body having an excellent breakage resistance, corrosion resistance, heat resistance and wear resistance and capable of being sintered at a relatively low pressure and low temperature can be provided. The feature thereof consists in a diamond sintered body comprising 50 to 99.9 volume % of diamond and the balance of a binder phase consisting of a single or mixed phase of a compound (C) or composite (C') of at least one element (A) selected from the group consisting of rare earth elements, Group 3B, 4A, 4B and 6B elements of Periodic Table, iron group, Mn, V, alkali metals and alkaline earth metals with a phosphorus compound (B), or of the above described compound (C) or composite (C') with an oxide of (A).

Abstract: A method of manufacturing a diamond sintered body includes the following steps: preparing a diamond powder having a particle size within a range of 0.1 to 10 .mu.m, coating the surface of each particle of the diamond powder with a sintering assistant agent including Pd within a range of 0.01 to 40 percent by weight and at least one iron family metal as a remainder, and liquid-phase sintering the coated diamond powder under a high pressure and high temperature condition. In this manner, a diamond sintered body having high strength and high wear-resistance, and containing diamond particles of 80 to 96 percent by volume, can be obtained.

Abstract: A polycrystalline diamond cutting tool comprises a tool material of polycrystalline diamond formed by low-pressure vapor deposition, which is bonded to a shank of cemented carbide through a brazing layer. The thickness of the polycrystalline diamond layer is set at 0.1 to 1.0 mm, while that of the brazing layer is set at 10 to 50 .mu.m. The brazing layer is made of a material having a melting point of 950.degree. to 1300.degree. C., which is in the form of an alloy layer containing at least one material selected from metals belonging to the groups IVa, Va, VIa and VIIa of the periodic table and carbides thereof and at least one material selected from Au, Ag, Cu, Pt, Pd and Ni. The polycrystalline diamond cutting tool is improved in heat resistance and tool strength. In order to improve deposition resistance of the cutting tool, the surface roughness of a tool rake face is set to be not more than 0.2 .mu.m in Rmax. A portion of the polycrystalline diamond layer up to a depth of 10 .mu.