# US 11,440,108 B2 · Rotary cutting tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,440,108 B2 - Document ID: US11440108B2 - Status: Granted - Kind: B2 - Application number: 16/644,813 - Filed: 2017-09-07 - Published: 2020-12-17 - Granted: 2022-09-13 - Earliest claimed: 2017-09-07 - Assignees: Sumitomo Electric Hardmetal Corp. - Applicants: Sumitomo Electric Hardmetal Corp. - Inventors: Nozomi Tsukihara; Yutaka Kobayashi; Minoru Yoshida - Web page: https://patentgrep.com/patent/US11440108B2 ## CPC - B23B 51/02: Twist drills - B23C 5/10: Shank-type cutters, i.e. with an integral shaft - C23C 28/044: {coatings specially adapted for cutting tools or wear applications} - C23C 28/046: {with at least one amorphous inorganic material layer, e.g. DLC, a-C:H, a-C:Me, the layer being doped or not} - C23C 30/00: Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process (C23C26/00, C23C28/00 take precedence) - B23B 2226/315: polycrystalline [PCD] - B23B 2228/10: Coatings - B23B 2251/204: Four cutting edges - B23C 2210/0492: different - B23C 2226/27: Composites, e.g. fibre reinforced composites - B23C 2226/315: polycrystalline [PCD] - B23C 2228/10: Coating - B23B: TURNING; BORING (arrangements for copying or controlling B23Q) - B23C: MILLING (broaching B23D; broach-milling in making gears B23F; arrangement for copying or controlling B23Q) - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) ## Abstract A rotary cutting tool includes a main body and a shank. The main body has a tip end. The shank is continuous with the main body on the side opposite to the tip end. The main body is provided with a first cutting edge having a positive twist angle, and a second cutting edge having a negative twist angle and separated from the first cutting edge. Each of the first cutting edge and the second cutting edge extends continuously from the tip end to the shank. ## Claims ### Claim 1 A rotary cutting tool comprising: a main body having a tip end; and a shank continuous with the main body on a side opposite to the tip end, the main body being provided with a first cutting edge having a positive twist angle, and a second cutting edge having a negative twist angle and separated from the first cutting edge, each of the first cutting edge and the second cutting edge extending continuously from the tip end to the shank, wherein the main body includes a base material, and a coating covering the base material, the coating is a polycrystalline diamond, the polycrystalline diamond includes a superficial layer and a deep layer, the deep layer is located between the superficial layer and the base material, a mean grain diameter of the superficial layer is smaller than a mean grain diameter of the deep layer, the coating includes at least one element selected from the group consisting of iron, molybdenum, and tungsten, and in a portion of the coating that is in contact with the base material, a total content of the at least one element is not less than 1.0×1015 atoms/cm3 and not more than 1.0×1018 atoms/cm3. ### Claim 2 (depends on 1) The rotary cutting tool according to claim 1, wherein a core thickness of the main body is not less than 0.4 times and not more than 0.9 times as large as a diameter of the main body. ### Claim 3 (depends on 1) The rotary cutting tool according to claim 1, wherein the superficial layer having a mean grain diameter of not less than 0.1 μm and not more than 5 μm. ### Claim 4 (depends on 3) The rotary cutting tool according to claim 3, wherein the base material has a surface roughness of not less than 0.2 μm and not more than 2.0 μm. ### Claim 5 (depends on 1) The rotary cutting tool according to claim 1, wherein the base material has a surface roughness of not less than 0.2 μm and not more than 2.0 μm. ### Claim 6 (depends on 1) The rotary cutting tool according to claim 1, wherein, at the tip end, a phase angle from the first cutting edge to the second cutting edge in a circumferential direction is different from a phase angle from the second cutting edge to the first cutting edge in the circumferential direction. ### Claim 7 (depends on 1) The rotary cutting tool according to claim 1, wherein each of the positive twist angle and the negative twist angle has an absolute value of not less than 3° and not more than 10°. ### Claim 8 (depends on 7) The rotary cutting tool according to claim 7, wherein the coating has a thicknesses of not less than 0.2 μm and not more than 2.0 μm.