Patent classifications
B23B2251/08
Drill for carbon-fiber composite material
The drill of the invention has: two cutting edges, each having a main cutting edge and a thinned cutting edge, wherein two relief surfaces formed symmetrically around rotation axis, first and second margin portions are formed, the first margin portions have a forward-end small-diameter portion with diameter smaller than the drill diameter, that is formed from the side of the drill forward-end toward the drill rearward-end, the second margin portions have a second forward-end small-diameter portion with diameter smaller than the first forward-end small-diameter portion, that is formed from the side of the drill forward-end toward the side of the drill rearward-end, the first forward-end small-diameter portion and the second forward-end small-diameter portion have inclination portions, the diameters of which gradually increase from the side of the drill forward-end toward the side of the drill rearward-end, and the inclination portions of the first forward-end small-diameter portion have relief surfaces.
MULTI-STEP DRILL WITH ASYMMETRIC STEP PROFILES
The present drill point arrangement includes a first and second land defined by a first and second flute, with a first cutting tip and a second cutting tip formed on the first and second lands respectively. The first cutting tip being positioned a first radial distance and the second cutting tip being positioned a second radial distance, each measured from the axis of rotation. The second cutting tip is positioned next in cutting tip sequence to the first cutting tip, and the second radial distance of the second cutting tip is greater than the first radial distance of the first cutting tip. Optionally, the first cutting tip is positioned a first axial distance and the second cutting tip is positioned a second axial distance, each measured from the front tip, and the second axial distance is greater than the first axial distance.
MULTI-STEP DRILL WITH ASYMMETRIC STEP PROFILES
The present drill point arrangement includes a first and second land defined by a first and second flute, with a first cutting tip and a second cutting tip formed on the first and second lands respectively. The first cutting tip being positioned a first radial distance and the second cutting tip being positioned a second radial distance, each measured from the axis of rotation. The second cutting tip is positioned next in cutting tip sequence to the first cutting tip, and the second radial distance of the second cutting tip is greater than the first radial distance of the first cutting tip. Optionally, the first cutting tip is positioned a first axial distance and the second cutting tip is positioned a second axial distance, each measured from the front tip, and the second axial distance is greater than the first axial distance.
Drill
A chip discharging flute is formed in a tip outer peripheral portion of a drill body rotated around an axis in a drill rotation direction. A cutting edge is formed in an intersection ridgeline portion between a wall surface of the chip discharging flute facing the drill rotation direction and a tip flank. The cutting edge includes a main cutting edge portion extending from an inner peripheral side toward an outer peripheral side of the drill body, and a cutting edge shoulder portion extending from an outer peripheral end of the main cutting edge portion to an outer periphery of the drill body, and is subjected to honing. Compared to the outer peripheral end of the main cutting edge portion, in an outer peripheral end of the cutting edge shoulder portion, a true rake angle is increased on a negative rake angle side, and a size of the honing decreases.