Mitsubishi Materials Corporation

Koichiro Naruke

Kazuya Yanagida

Tadashi Yamamoto

Hiroyuki Higashi

Nobuyuki Matsuda

Sohei Takahashi

Provided is a drill suitable for high-efficiency working. A cut debris discharge groove is formed in the outer periphery of the drill body front end section rotated about the axis, and a cutting edge is formed at the front end of the drill body. The wall surface of the cut debris discharge groove, which faces the rotational direction of the drill, is formed to have a concave curve line shape in a cross-section perpendicular to the axis, the concave curve line shape extending along a first circular arc.

Drill

A drill comprises a drill body that is rotatable on an axis. Chip evacuating flutes, which are open on front flanks of the drill body and are extended rearwards, are formed in a periphery of the drill body on its front side. Cutting edges are formed along ridge lines where the front flanks intersect with wall surfaces of the chip evacuating flutes facing a drill rotating direction. At least first and second front flanks are formed on the front flanks in order of their locations in the drill rotating direction from its leading side to its trailing side. A clearance angle of the second front flank is greater than that of the first front flank. Intersection lines of the first and second front flanks cross the cutting edges.

A coolant-hole equipped drill includes a drill main body, a cutting edge portion which has a tip flank, a chip discharging groove provided with a front groove wall surface and a rear groove wall surface, a cutting edge formed at a ridge line portion where the front groove wall surface and the tip flank intersect with each other, a land portion formed between the chip discharging grooves adjacent to each other in the rotating direction, and a coolant hole drilled at the land portion and opened at the tip flank. The coolant hole includes a front hole wall surface, a rear hole wall surface, and an outer-circumference hole wall surface.

Coolant-hole equipped drill

A guide portion prevents the drilling hole from curving due to a skipping rope phenomenon, and also prevents the inner wall face of the drilling hole from being damaged, so that its surface roughness can be improved. Chip evacuating flutesare formed in the periphery of a drill bodywhich has a stick shape and is rotatable on its axis O, from its front flanktoward the rear side. Cutting edgesA are formed along ridge lines where the front flanksintersect with wall facesA which are in the chip evacuating flutesand face in a drill rotational direction T. A cutting edge section, where the cutting edgesA are formed, is provided in the front side of the drill body. A cutting edge sectionhas an external diameter which is smaller toward the rear side in the axis O direction than the external diameter D at the cutting edgesA. A guide portionhas a maximum external diameter partA at the front periphery side, and is provided to the rear side of the cutting edge section An external diameter at the maximum external diameter partA is larger than the external diameter at the rear of the cutting edge section, and is smaller than or equal to the external diameter D at the cutting edgesA. The maximum external diameter partA of the guide portionshows a smooth convex curve shape in a rotatory figure obtained by rotating it on the axis O.

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Anpachi-gun, Japan

Koichiro Naruke