Abstract: The invention provides a high-speed tool steel gear cutting tool in which fracture or chipping does not occur at the cutting edge, and which realizes excellent cutting performance over long periods. Moreover, a method of manufacturing a gear cutting tool including: a step for quenching a tool material comprising high-speed tool steel and which has been rough processed to a shape corresponding to a final shape of a gear cutting tool, to transform a structure of the tool material into martensite, a step for temperling the tool material after quenching to transform any residual austenite dispersingly distributed throughout a matrix of the martensite structure formed by the quenching, into martensite, and a step for finishing the tool material after tempering to a final shape, is characterized in that the tool material after quenching is subjected to sub-zero treatment involving cooling and holding at a temperature of less than −150 ° C.

Abstract: The present invention is for providing a milling cutter which can provide for both an improvement in sharpness and a retention of cutting edge strength, while making the transverse cross-section an easily manufactured polygon shape. The milling cutter with a plurality of peripheral cutting edges (12) has a polygon shape transverse cross-section. The polygon is a convex polygon with one more apex point (13) existing between apex point pairs constituting the peripheral cutting edges with an apex angle greater than that of the apex points, and a longer side of the sides on either side of each of the peripheral cutting edges constitutes a rake face (14), while a shorter side constitutes a relief face (16).

Abstract: A heat treatment method of steel is capable of enhancing wear resistance, mechanical properties and dimensional stability of the steel due to the reduction of the retained austenite amount to substantially zero. In the method, an article of the steel is subjected to a quenching and then subzero treatment including cooling it at a cooling rate of 1 to 10° C./min. to a cooling temperature and holding the cooling temperature for a predetermined period of time.

Abstract: The invention provides a high-speed tool steel gear cutting tool in which fracture or chipping does not occur at the cutting edge, and which realizes excellent cutting performance over long periods. Moreover, a method of manufacturing a gear cutting tool including: a step for quenching a tool material comprising high-speed tool steel and which has been rough processed to a shape corresponding to a final shape of a gear cutting tool, to transform a structure of the tool material into martensite, a step for temperling the tool material after quenching to transform any residual austenite dispersingly distributed throughout a matrix of the martensite structure formed by the quenching, into martensite, and a step for finishing the tool material after tempering to a final shape, is characterized in that the tool material after quenching is subjected to sub-zero treatment involving cooling and holding at a temperature of less than −150° C.

Abstract: The present invention is for providing a milling cutter which can provide for both an improvement in sharpness and a retention of cutting edge strength, while making the transverse cross-section an easily manufactured polygon shape. The milling cutter with a plurality of peripheral cutting edges (12) has a polygon shape transverse cross-section. The polygon is a convex polygon with one more apex point (13) existing between apex point pairs constituting the peripheral cutting edges with an apex angle greater than that of the apex points, and a longer side of the sides on either side of each of the peripheral cutting edges constitutes a rake face (14), while a shorter side constitutes a relief face (16).

Abstract: The present invention provides a member coated with a hard coating and to attain excellent wear resistance. The hard coating includes: an adhesion reinforcing layer formed on a surface of the member; and a second layer formed on the adhesion reinforcing layer and having a composition represented by the following formula: (AlpTiqVr)(NuCv) where 0≦p≦0.75, 0.20≦q≦0.75, 0.10≦r≦0.75, p+q+r=1, 0.6≦u≦1, and u+v=1. In order to further enhance the adhesion of the hard coating to the member, an intermediate layer may be formed between the first and second layers.