Cutting tool made from cubic boron nitride-based sintered material

Abstract

The purpose of the present invention is to provide a cBN tool which can exhibit excellent chipping resistance and excellent wear resistance even when used for the intermittent cutting of a high-hardness steel and can also exhibit excellent cutting performance throughout long-term use. The purpose can be achieved by providing a cutting tool made from a cBN sintered material, in which a cBN sintered material that contains at least cBN particles as a hard phase component is employed as a tool base, wherein each of the cBN particles has an Al2O3 layer that has, on the surface thereof, slits formed at an average formation ratio of 0.02 to 0.20 inclusive and has an average layer thickness of 1.0 to 10 nm, the cBN sintered material has, around the periphery of each of the cBN particles, a binder phase comprising TiN alone or a combination of TiN and TiC, TiB2, TiCN, AlN, Al2O3, WC or the like, and the sum total of the content of Al2O3 formed on the surface of each of the cBN particles and the content of Al2O3 present in the binder phase is 2 to 40 vol% on average wherein the volume of a region of each of the cBN particles which lies between the surface of each of the cBN particles and a zone located at the depth of 50 nm from the above-mentioned surface is defined as 100 vol%.

Description

technical field [0001] The present invention relates to a cubic boron nitride (hereinafter referred to as cBN)-based sintered cutting tool (hereinafter referred to as cBN tool) excellent in chipping resistance and chipping resistance. [0002] This application claims priority based on Japanese Patent Application No. 2012-112492 filed in Japan on May 16, 2012, and Japanese Patent Application No. 2013-60098 filed in Japan on March 22, 2013, and the contents thereof are incorporated herein by reference. . Background technique [0003] Conventionally, cBN tools using a cBN-based sintered material (hereinafter referred to as cBN sintered body) as a tool material with low affinity with the workpiece are known for cutting iron-based workpieces such as steel and cast iron. . [0004] For example, as shown in Patent Document 1, it is known that cBN is contained as a hard phase in an amount of 40 to 80% by volume, and ceramics such as carbides, nitrides, and borides of IVB, VB, and ...

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Problems solved by technology

[0008] In the conventional cBN tool described in the patent document 2, Al 2 o 3 Layer-coated cBN particles are used as raw material powder to make cBN sintered body, so that when cBN sintered body is used as tool matrix, cBN will not be directly exposed on the surface of the rake face, which helps to improve wear resistance, but because cBN with Al 2 o 3 Residual stress due to differences in thermal expansion characteristics of the layers, and when used for interrupted cutting of high-hardness steel, chipping resistance and chipping resistance are not sufficient, so there is also a problem of short tool life

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