Surface-coated cutting tool

Abstract

The present invention provides a surface-coated cutting tool in which a hard coating layer demonstrates excellent peeling and chipping resistance in high-speed intermittent machining. According to the surface-coated cutting tool provided by the invention, the surface of the tool substrate is coated by a lower layer composed of a Ti compound layer and an upper layer composed of an a-type Al2O3 layer formed by evaporation; if a field-emission scanning electron microscope and an electronic back scattering diffraction image device are used for calculating the normal tilt angle distribution of a plane (0001) of AI203 crystal grain within a range of 0-90 degrees close to boundary of the lower layer, the test angle within the range of 0-45 degrees is divided by interval of 0.25 degree, and is indicated by tilt angle degree distribution curve graph formed by combining angles in each divided areas, then the sum total degrees of the lower region accounts for a ratio of 30-70% within the range of 25-35 degrees; and when the tilt angle is tested with same AI203 crystal grain in the upper layer, the sum total degrees of the upper region accounts for a ratio of more than 60% within the range of 0-10 degrees.

Description

technical field [0001] The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) capable of cutting various steels or cast irons even under intermittent cutting conditions in which high-speed and intermittent impact loads act on the cutting edge The hard coating exhibits excellent peeling resistance and chipping resistance even during processing, and exhibits excellent wear resistance over a long period of time. Background technique [0002] In the past, it is known that there are usually substrates composed of tungsten carbide (hereinafter, represented by WC)-based cemented carbide or titanium carbonitride (hereinafter, represented by TiCN)-based cermets (hereinafter, they are collectively referred to as tool substrates). A coated tool formed by vapor-depositing a hard coating layer consisting of the following (a) and (b) on the surface: [0003] (a) The lower layer is a Ti compound layer, consisting of Ti carbide (hereinafte...

AI Technical Summary

Problems solved by technology

[0013] In recent years, the performance of cutting devices has been significantly improved. On the other hand, for labor saving and energy saving in cutting processing, there is a strong demand for further cost reduction. As a result, cutting processing speeds have become higher, and there are intermittent cutting, etc. A high load tends to act on the cutting edge, but in the current situation of the above-mentioned conventional coated tools, there is no problem when it is used for continuous cutting or intermittent cutting of steel or cast iron under normal conditions, but especially when using this When used in high-speed interrupted cutting conditions, the lower layer composed of the Ti compound layer constituting the hard coating layer and the Al 2 o 3 The adhesion strength of the upper layer composed of layers is not sufficient, and the service life is reached in a relatively short period of time due to the occurrence of abnormal damage such as peeling and chipping between the upper layer and the lower layer.

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