To provide a surface covered cemented carbide made miniature drill with a tip cutting blade surface to display excellent chipping resistance in high speed drilling work.
This surface covered cemented carbide made miniature drill is constituted of a groove forming part and a shank part, at least the groove forming part contains, by mass, Co: 4-13%, Cr: 0.1-0.7%, V: 0.1-0.5% as binding phase forming components and the rest is constituted by forming a hard covered layer made of an artificial diamond layer on a surface of a base body constituted of cemented carbide having a composition made of tungsten carbide and unavoidable impurities as a hard phase forming component in average layer thickness of 0.5-50 μm, the groove forming part is divided into a main body part, an intermediate part and a tip cutting blade surface part along the lengthy direction, a Co content of the cemented carbide base body of the main body part: 10-13%, a Co content of a cemented carbide base body of the intermediate part: 7-9%, and a Co content of a cemented carbide base body of the tip cutting blade surface part: 4-6%.
YANAI TOSHIYUKI
OKADA KAZUKI
TAKAHASHI SATOSHI
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