Cutting tool made of surface-coated cubic boron nitride-based ultra-high pressure sintered material having high peeling resistance

Abstract

The invention provides a cutting tool made of surface-coated cubic boron nitride-based ultra-high pressure sintered material, which develops good property of peeling resistance when high-rigidity steel undergoes high-speed cutting. The cutting tool is formed by forming hard coating layer on the surface of CBN-based ultra-pressure sintered body whose cubic boron nitride is 50-85 capacity%. The hard coating layer comprises a lower layer and an upper layer whose average layer thickness is 1.5-3Mum. The lower layer has a complex nitride layer satisfying a formula: [Ti1-XA1X]N, wherein in terms of atomic ratio, X is 0.30-0.60. The upper layer has a thin layer A and a thin layer B which is alternative and has 0.03-0.3Mum average layer thickness. The thin layer A includes a complex nitride layer satisfying a formula: [Ti1-XA1X]N, and the thin layer B includes TiN layer. The surface roughness, residual stress and nano-indentation hardness are set to be a predetermined value.

Description

technical field [0001] The present invention relates to a cutting tool made of surface-coated cubic boron nitride-based ultra-high pressure sintered material (hereinafter referred to as coated cBN-based sintered tool). The hard coating layer of the cutting tool has excellent high-temperature hardness, high-temperature Strength, heat resistance, and excellent adhesion, so even when used in high-speed cutting of high-hardness steel such as alloy steel and bearing steel quenched material, it can also exhibit excellent peeling resistance, and it is also resistant to cutting for a long time. The excellent finishing surface accuracy of the workpiece can be maintained, and a hard coating layer is formed on the surface of the cutting tool base body composed of cubic crystal boron nitride-based ultra-high pressure sintered material. Background technique [0002] Generally, the following tools are known among the coated cBN-based sintered tools: an indexable insert detachably mounted ...

AI Technical Summary

Problems solved by technology

[0009] (a) Composite nitrides of Ti and Al ([Ti 1-X Al X ]N) layer has predetermined heat resistance, high-temperature hardness and high-temperature strength in the range of Al content ratio X (atomic ratio) in the range of 0.30 to 0.60, and has the wear resistance required under normal cutting conditions, but In the high-speed cutting of high-hardness steel that is accompanied by extremely high heat generation on the blade or at the same time applying intermittent or high-impact mechanical loads to the blade, due to the complex nitrides including Ti and Al ([Ti 1-X Al X The high-temperature strength of the hard coating layer of the ]N) layer is insufficient, so boundary abnormal damage occurs at the boundary portion of the blade, and therefore the precision of the finished surface of the workpiece cannot be maintained, and the service life is reached in a relatively short period of time

[0010] (b) On the other hand, the Ti nitride (TiN) layer has excellent high-temperature strength and impact strength, but due to insufficient heat resistance and high-temperature hardness, it is accompanied by a large heat generation and a large mechanical load is applied. In high-speed cutting of high-hardness steel, even if the hard coating layer consists of only a Ti nitride (TiN) layer, it does not have sufficient wear resistance.

Images