SMALL-DIAMETER DRILL - SUMITOMO ELEC HARDMETAL CORP

Title:

SMALL-DIAMETER DRILL

Document Type and Number:

WIPO Patent Application WO/2014/065361

Kind Code:

A1

Abstract:

The problem addressed by the present invention is, in order to improve a small-diameter drill, to suppress strength reduction of the outer peripheral part of a cutting blade without providing a return section while securing the sharpness of the outer peripheral part of the cutting blade without defect, and to obtain good cutting accuracy and good chip treatability. In a small-diameter drill having a diameter (φ) no greater than 3 mm, on the tip of which cross-thinning has been performed, a flute-section cutting blade (4a) is curved in a concave shape in front view, the concave amount (d) from a hypothetical straight line being within a range of 0.5-2% of the drill diameter (D) in relation to a hypothetical straight line (SL) connecting the outer end (P) in the radial direction of the flute-section cutting blade and the outer end (Q) in the radial direction of the thinning section cutting blade; the ratio of the length (B) of the thinning section cutting blade and the length (A) of the flute-section cutting blade is set at 0.6-0.9:1; and in the cross-sectional view perpendicular to the axis, the curvature radius (R1) of the heel-side groove surface of the flute is smaller than the curvature radius (R2) of the flute-section cutting blade-side groove surface.

Inventors:

JINDAI MASAAKI (JP)

Application Number:

PCT/JP2013/078804

Publication Date:

May 01, 2014

Filing Date:

October 24, 2013

Export Citation:

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Assignee:

SUMITOMO ELEC HARDMETAL CORP (JP)

International Classes:

B23B51/00

Foreign References:

US5888036A	1999-03-30
JPS60120712U	1985-08-15
JPS60120713U	1985-08-15
JP2007229900A	2007-09-13
JPS57107716A	1982-07-05
JP2001225216A	2001-08-21

Other References: