CUTTING TOOL MADE FROM SURFACE-COATED CUBIC BORON NITRIDE GROUP ULTRAHIGH-PRESSURE SINTERED MATERIAL SHOWING EXTREMELY EXCELLENT FINISHED SURFACE PRECISION AT HIGH-SPEED MACHINING OF HIGH-HARDNESS STEEL FOR LONG PERIOD

摘要

PPROBLEM TO BE SOLVED: To provide a cutting tool composed of a surface-coated cubic boron nitride group ultrahigh-pressure sintered material showing extremely excellent finished surface precision at the high-speed machining of high-hardness steel for a long period of time. PSOLUTION: In the cutting tool composed of a surface-coated cubic boron nitride group ultrahigh-pressure sintered material in which a hard coated layer is evaporated on the surface of a machining chip body having a structure in which an ultrahigh-pressure sintering reacted object is present on an interface between a cubic boron nitride phase forming a dispersed phase and a titanium nitride phase forming a continuous phase, (a) the hard coated layer is formed by a lower layer having an average layer thickness of 1.5-3 micrometers and an upper layer having an average layer thickness of 0.3-3 micrometers, (b) the lower layer is formed of a compound nitride of Ti, Al, and Si which satisfies a specific compositional formula, and (c) the upper layer has an alternately laminated layer structure of a thin layer A and thin layer B in which an average layer thickness of each layer is 0.05-0.3 micrometers. Here, the thin layer A is formed of a compound nitride layer of Ti, Al, and Si which satisfies the specific formula, and the thin layer B is formed of a Ti nitride (TiN) layer. PCOPYRIGHT: (C)2008,JPO&INPIT