US 12,186,815 B2
Cutting tool
Mayuka Segawa, Hyogo (JP); Naoki Watanobe, Hyogo (JP); Taisuke Higashi, Hyogo (JP); Takashi Harada, Hyogo (JP); and Satoru Kukino, Osaka (JP)
Assigned to SUMITOMO ELECTRIC HARDMETAL CORP., Hyogo (JP); and Sumitomo Electric Industries, Ltd., Osaka (JP)
Appl. No. 18/011,441
Filed by SUMITOMO ELECTRIC HARDMETAL CORP., Hyogo (JP); and SUMITOMO ELECTRIC INDUSTRIES, LTD., Osaka (JP)
PCT Filed Jun. 17, 2021, PCT No. PCT/JP2021/023085
§ 371(c)(1), (2) Date Dec. 19, 2022,
PCT Pub. No. WO2021/261380, PCT Pub. Date Dec. 30, 2021.
Prior Publication US 2023/0182218 A1, Jun. 15, 2023
Int. Cl. B23C 5/10 (2006.01); B23B 27/20 (2006.01)
CPC B23C 5/1018 (2013.01) [B23B 27/20 (2013.01); B23B 2222/28 (2013.01); B23B 2226/315 (2013.01); B23B 2265/34 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A cutting tool that rotates about a rotation axis, the cutting tool comprising:
a tip end portion, wherein
the tip end portion includes a partially spherical surface that is brought into contact with a workpiece,
the partially spherical surface is provided with a plurality of concave indentations recessed into the partially spherical surface, defining a plurality of recesses, each recess having a bottom surface and being disposed apart from each other, and
a sharp opening edge of each of the plurality of recesses defined at an intersection between an upper most portion of the recess and the partially spherical surface constitutes a cutting edge,
wherein the opening edge of each of the plurality of recesses has in plan view an equivalent circle diameter having a closed shape, the equivalent circle diameter being greater than or equal to 1 μm and less than or equal to 100 μm, wherein the equivalent circle diameter of each of the recesses is a square root of a value obtained by dividing an area of the recess in plan view by πT/4; and
the tip end portion is formed of binderless cubic boron nitride or nano polycrystalline diamond.