# US 7,950,880 B2 · Spiral flute tap > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,950,880 B2 - Document ID: US7950880B2 - Status: Granted - Kind: B2 - Application number: 11/582,806 - Filed: 2006-10-18 - Published: 2008-04-24 - Granted: 2011-05-31 - Earliest claimed: 2006-10-18 - Assignees: Kennametal Inc.; Yamawa Manufacturing Ltd. - Inventors: Willard E. Henderer; Stephen M. George; Steven R. Burns; Sadayuki Akaki - Web page: https://patentgrep.com/patent/US7950880B2 ## CPC - B23G 5/06: Taps (chucks therefor B23B31/00) - B23P 15/52: taps - B23G 2200/26: Coatings of tools - B23G 2200/48: Spiral grooves, i.e. spiral flutes - B23G 2225/28: Hard metal, i.e. cemented carbides - B23G 2225/32: High speed steel - B23G 2225/56: Titanium carbide nitride (TiCN) - B23G 2225/60: Titanium nitride - Y10T 408/9048: Extending outwardly from tool-axis - Y10T 408/906: Axially spaced - Y10T 408/9097: Spiral channel - B23G: THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH (making helical grooves by turning B23B5/48, by milling B23C3/32, by forging, pressing, or hammering B21K1/56, by grinding B24B19/02; arrangements for copying or controlling B23Q; thread-forming by corrugating tubes B21D15/04, by rolling B21H3/02) - B23P: METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS (arrangements for copying or controlling B23Q) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A cutting tool that includes an elongate body that has a forward end and a rearward end. The elongate body has a fluted portion that beginning near and extends in a rearward direction from the forward end. The fluted portion has a flute that defines a cutting edge. The flute presents a concave cutting face wherein the concave cutting face is defined by a first radius. The flute further presents a concave core surface adjacent to the concave cutting face wherein the concave core surface is defined by a second radius. The flute presents a convex heel surface adjacent to the concave core surface wherein the convex heel surface is defined by a fourth radius. ## Claims ### Claim 1 A spiral fluted cutting tap for cutting threads into a wall of a bore, the tap comprising: an elongate body having a forward end and a rearward end; the elongate body having a fluted portion beginning near and extending in a rearward direction from the forward end, and the fluted portion having a spiral flute defining a cutting edge adapted to cut threads; the spiral flute presenting a concave cutting face, and the concave cutting face being defined by a first radius; the spiral flute further presenting a concave core surface adjacent to the concave cutting face, and concave core surface being defined by a second radius; the spiral flute further presenting a convex blending surface adjacent the concave core surface, and the convex blending surface being defined by a third radius; and the spiral flute presenting a convex heel surface adjacent to the convex blending surface, and the convex heel surface being defined by a fourth radius. ### Claim 2 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the cutting tap has a cutting tap diameter, and the first radius defining the concave cutting face is equal to or greater than the cutting tap diameter. ### Claim 3 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the concave cutting face defining a chordal hook angle. ### Claim 4 (depends on 3) The spiral fluted cutting tap according to claim 3 wherein the chordal hook angle ranges between ten degrees negative and fifteen degrees positive. ### Claim 5 (depends on 3) The spiral fluted cutting tap according to claim 3 wherein the chordal hook angle being equal to about zero degrees. ### Claim 6 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the spiral flute has a helix angle between about ten degrees and about fifty-five degrees. ### Claim 7 (depends on 6) The spiral fluted cutting tap according to claim 6 wherein the helix angle ranges between about forty degrees and about fifty degrees. ### Claim 8 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body has four spiral flutes. ### Claim 9 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the cutting tap has a core diameter, the cutting tap has a cutting tap diameter, and the core diameter ranges between about thirty percent and about fifty percent of the cutting tap diameter. ### Claim 10 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the cutting tap has a cutting tap diameter, and the second radius ranges between about five percent and about twenty-five percent of the cutting tap diameter. ### Claim 11 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the cutting tap has a cutting tap diameter, and the fourth radius ranges between about twenty percent and about thirty percent of the cutting tap diameter. ### Claim 12 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body has a plurality of the spiral flutes, the cutting tap has a cutting tap diameter, and a land is between each adjacent one of the spiral flutes, and the land being defined by an inscribed circle having a third diameter, and the third diameter ranging between about fifteen percent and about twenty-five percent of the cutting tap diameter. ### Claim 13 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body having a cutting tap diameter, and the third radius ranging between about fifty percent and about two hundred percent of the cutting tap diameter. ### Claim 14 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body contains three of the spiral flutes. ### Claim 15 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body contains five of the spiral flutes. ### Claim 16 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body comprises cobalt-cemented tungsten carbide, and the cobalt content ranging between about ten weight percent and about sixteen weight percent. ### Claim 17 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body comprises high-speed steel. ### Claim 18 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the elongate body further includes a coating scheme, and wherein the coating scheme comprises one or more layers of one or more of the following: metal nitrides, carbides, carbonitrides, borides and/or oxides, wherein the metal is chosen from one or more of the following: aluminum, silicon and the transition metals from Groups IVa, Va, VIa of the Periodic Chart. ### Claim 19 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the cutting edge is honed with a radius between 1 and 100 micrometers. ### Claim 20 (depends on 1) The spiral fluted cutting tap according to claim 1 wherein the edges adjacent to the convex heel surface being honed with a radius between 1 and 300 micrometers. ### Claim 21 A spiral fluted cutting tap for cutting threads into a wall of a bore, the tap comprising: an elongate body having a forward end and a rearward end; the elongate body having a fluted portion beginning near and extending in a rearward direction from the forward end, and the fluted portion having a spiral flute defining a cutting edge adapted to cut threads; the spiral flute presenting a concave cutting face, and the concave cutting face being defined by a first radius; the spiral flute further presenting a concave core surface adjacent to the concave cutting face, and concave core surface being defined by a second radius; the spiral flute further presenting a convex blending surface adjacent the concave core surface, and the convex blending surface being defined by a third radius; the spiral flute presenting a convex heel surface adjacent to the convex blending surface, and the convex heel surface being defined by a fourth radius; and the spiral fluted cutting tap having a core diameter, and the core diameter remaining substantially constant along the length of the fluted portion. ### Claim 22 (depends on 21) The spiral fluted cutting tap according to claim 21 wherein the elongate body having a cutting tap diameter, and the third radius ranging between about fifty percent and about two hundred percent of the cutting tap diameter.