# US 10,441,995 B2 · Method for producing forged crankshaft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,441,995 B2 - Document ID: US10441995B2 - Status: Granted - Kind: B2 - Application number: 15/560,504 - Filed: 2016-03-31 - Published: 2018-03-01 - Granted: 2019-10-15 - Earliest claimed: 2015-04-03 - Assignees: Nippon Steel Corporation - Applicants: Nippon Steel & Sumitomo Metal Corporation - Inventors: Sho Takamoto; Kenji Tamura; Tomohisa Yamashita; Kunihiro Yabuno; Ken Yoshino; Hiroyuki Kurokawa; Junichi Okubo; Koichiro Ishihara - Web page: https://patentgrep.com/patent/US10441995B2 ## CPC - B21K 1/08: crankshafts - B21J 5/027: {Trimming} - B23P 15/00: Making specific metal objects by operations not covered by a single other subclass or a group in this subclass - F16C 3/08: made in one piece (features relating to lubrication F16C3/14, to cooling F16C3/16) - B23P 2700/07: Crankshafts - B21K: MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS (making particular articles by working sheet metal without essentially removing material B21D; processing wire B21F; making pins, needles or nails B21G; making particular articles by rolling B21H; forging machines, pressing machines, hammering machines, in general B21J; making chains B21L; plating B23K) - B21J: FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES (rolling of metal B21B; making particular products by forging or pressing B21K; cladding or plating B23K; finishing surfaces by hammering B23P9/04; compacting surfaces by blasting with particulate material B24C1/10; general features of presses, presses for consolidating scrap B30B; furnaces in general F27) - B23P: METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS (arrangements for copying or controlling B23Q) - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS ## Abstract The disclosed production method includes a die forging step of obtaining a forged blank with flash having a crankshaft shape, and a trimming step of removing the flash from the forged blank while nipping the forged blank with a pair of holding dies. In the forged blank, at least one of the rough crank arms have, in a region near an adjacent rough pin, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm. When the forged blank is nipped with the pair of holding dies, the first excess portion is deformed by the pair of holding dies to bulge toward an adjacent rough journal. ## Claims ### Claim 1 A method for producing a forged crankshaft including journals serving as a center of rotation, pins decentered from the journals, and crank arms connecting the journals and the pins, wherein the forged crankshaft further includes counterweights integrated with all or some of the crank arms, the method comprising: a die forging step of obtaining a forged blank with flash having a crankshaft shape; and a trimming step of removing the flash from the forged blank while nipping the forged blank with a pair of holding dies, wherein: the forged blank includes rough journals, rough pins, rough crank arms, and rough counterweights, which correspond to the journals, the pins, the crank arms, and the counterweights of the forged crankshaft, respectively; at least one of the rough crank arms has, in a region near an adjacent one of the rough pins, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm; and when the forged blank is nipped with the pair of holding dies in the trimming step, the first excess portion is deformed by the pair of holding dies to bulge toward an adjacent one of the rough journals. ### Claim 2 (depends on 1) The method for producing a forged crankshaft according to claim 1, wherein the rough crank arm has, in the region near the adjacent rough pin, first excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm. ### Claim 3 (depends on 2) The method for producing a forged crankshaft according to claim 2, wherein in the trimming step, the first excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough journal while a holder is holding a lower surface of the flash; and the holder moves along with a movement of the pair holding dies while keeping holding the lower surface of the flash. ### Claim 4 (depends on 3) The method for producing a forged crankshaft according to claim 3, wherein at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm; and when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin. ### Claim 5 (depends on 4) The method for producing a forged crankshaft according to claim 4, wherein the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm. ### Claim 6 (depends on 2) The method for producing a forged crankshaft according to claim 2, wherein at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm; and when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin. ### Claim 7 (depends on 6) The method for producing a forged crankshaft according to claim 6, wherein the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm. ### Claim 8 (depends on 1) The method for producing a forged crankshaft according to claim 1, wherein in the trimming step, the first excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough journal while a holder is holding a lower surface of the flash; and the holder moves along with a movement of the pair holding dies while keeping holding the lower surface of the flash. ### Claim 9 (depends on 8) The method for producing a forged crankshaft according to claim 8, wherein at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm; and when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin. ### Claim 10 (depends on 9) The method for producing a forged crankshaft according to claim 9, wherein the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm. ### Claim 11 (depends on 1) The method for producing a forged crankshaft according to claim 1, wherein in the trimming step, the first excess portion is deformed by crushing or bending. ### Claim 12 (depends on 11) The method for producing a forged crankshaft according to claim 11, wherein at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm; and when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin. ### Claim 13 (depends on 12) The method for producing a forged crankshaft according to claim 12, wherein the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from-outer peripheries of two side portions of the rough crank arm. ### Claim 14 (depends on 1) The method for producing a forged crankshaft according to claim 1, wherein at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm; and when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin. ### Claim 15 (depends on 14) The method for producing a forged crankshaft according to claim 14, wherein the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm. ### Claim 16 (depends on 14) The method for producing a forged crankshaft according to claim 14, wherein the rough crank arm having the second excess portion is the rough crank arm incorporating a rough counterweight. ### Claim 17 (depends on 14) The method for producing a forged crankshaft according to claim 14, wherein the rough crank arm having the second excess portion is the rough crank arm not incorporating a rough counterweight. ### Claim 18 (depends on 14) The method for producing a forged crankshaft according to claim 14, wherein in the trimming step, the second excess portion is deformed by crushing or bending.