# US 2009/0260467 A1 · Steering rack and method of manufacturing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260467 A1 - Document ID: US20090260467A1 - Status: Published application - Kind: A1 - Application number: 12/090,223 - Filed: 2006-10-12 - Published: 2009-10-22 - Earliest claimed: 2005-10-12 - Assignees: Nsk Ltd. - Inventors: Kazuto Kobayashi; Kotaro Hirota; Kiyoshi Ootsuka - Web page: https://patentgrep.com/patent/US20090260467A1 ## CPC - B21D 15/04: transversely, e.g. helically - B21K 1/063: {hollow (hollow racks B21K1/768)} - B21K 1/768: {hollow} - B62D 3/126: {characterised by the rack} - Y10T 29/49474: Die-press shaping - Y10T 74/1967: Rack and pinion - B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F) - 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) - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract When a punch is downwardly pressed, an inner circumferential surface of a first rack blank bites into a top surface of a second rack blank. A blank material upwardly flows due to a reaction force and is used to form rack teeth. Thus, a filling degree of the teeth with the material is enhanced. At the time when the forming of the rack teeth is finished, a gap is left between the inner circumferential surface of the first rack blank and the outer circumferential surface of the second rack blank. Thus, a die is not put into a sealed condition. Consequently, a forming load is small so that the lifetime of the die is lengthened. Also, the top surface of the second rack blank bites into a bore hole portion of the first rack blank so that the first rack blank and the second rack blank are joined together. Accordingly, the rigidity of the entire rack teeth is increased. ## Claims ### Claim 1 A method of manufacturing a steering rack, the method comprising: providing a first rack blank in a form of a pipe having a bore hole, and a second rack blank or a mandrel having such a cross-sectional shape that a gap is provided between the second rack blank or the mandrel and an inner circumferential surface of the first rack blank; inserting the second rack blank or the mandrel into the bore hole of the first rack blank; restraining an outer circumferential surface of the first rack blank other than a rack teeth forming portion of the first rack blank by a first die; forming rack teeth on the first rack blank by pressing a punch having a rack teeth shaped portion onto the rack teeth forming portion of the first rack blank, and causing the first rack blank to contact an outer circumferential surface of the second rack blank or the mandrel facing the rack teeth forming portion of the first rack blank; and allowing a blank material, which has been excluded in the forming the rack teeth, to flow into the gap between the inner circumferential surface of the first rack blank and the second rack blank or the mandrel such that the blank material is accommodated in the gap. ### Claim 2 (depends on 1) The method according to claim 1, wherein the providing the first rack blank and the second rack blank or the mandrel comprises providing the first rack blank having a hollow cylindrical shape. ### Claim 3 (depends on 1) The method according to claim 1, wherein the providing the first rack blank and the second rack blank or the mandrel comprises providing the second rack blank which is solid. ### Claim 4 (depends on 3) The method according to claim 3, wherein the providing the first rack blank and the second rack blank or the mandrel further comprises providing the second rack blank having a cylindrical shape. ### Claim 5 (depends on 1) The method according to claim 1, wherein the providing the first rack blank and the second rack blank or the mandrel comprises providing the second rack blank having an axial length which is equal to or longer than a length of the rack teeth forming portion of the first rack blank. ### Claim 6 (depends on 1) The method according to claim 1, wherein the providing the first rack blank and the second rack blank or the mandrel comprises forming teeth on the outer circumferential surface of the second rack blank facing the rack teeth forming portion of the first rack blank at a pitch equal to a pitch of the rack teeth shaped portion of the punch. ### Claim 7 (depends on 5) The method according to claim 5, wherein the providing the first rack blank and the second rack blank or the mandrel further comprises forming teeth on the outer circumferential surface of the second rack blank facing the rack teeth forming portion of the first rack blank at a pitch equal to a pitch of the rack teeth shaped portion of the punch. ### Claim 8 (depends on 1) The method according to claim 1, further comprising: after the allowing the blank material, which has been excluded, to flow into the gap such that the blank material is accommodated in the gap, sizing the rack teeth to obtain a required rack teeth by holding and pressing the first rack blank between a second die having a required rack teeth shaped portion and a third die having an outer circumference corresponding to a required shape of the outer circumferential surface of the first rack blank other than the rack teeth forming portion. ### Claim 9 (depends on 8) The method according to claim 8, wherein the sizing the rack teeth comprises forming the required rack teeth while narrowing a tooth width of a root of the rack teeth formed on the first rack blank to a required tooth width. ### Claim 10 (depends on 8) The method according to claim 8, further comprising: after the sizing the rack teeth, extracting the mandrel from the bore hole of the first rack blank. ### Claim 11 (depends on 1) The method according to claim 1, wherein the forming the rack teeth comprises: firstly forming the rack teeth by a first punch formed with a first rack teeth shaped portion having a pressure angle that is smaller than a pressure angle of a required rack teeth shape; and secondly forming the rack teeth by a second punch formed with a rack teeth shaped portion having a pressure angle that is closer to the pressure angle of the required rack teeth shape than the pressure angle of the first rack teeth shaped portion. ### Claim 12 (depends on 9) The method according to claim 9, wherein the sizing the rack teeth further comprises further forming the required rack teeth without restraining the tooth width of the root of the rack teeth formed on the first rack blank. ### Claim 13 (depends on 1) The method according to claim 1, wherein the forming the rack teeth comprises forming the rack teeth having a tooth height which is larger than a tooth height of a required rack teeth shape. ### Claim 14 (depends on 1) The method according to claim 1, wherein the forming the rack teeth comprises forming the rack teeth by the punch having the rack teeth shaped portion such that a pressure angle of a rack tooth shape at each end in an axial direction of the first rack blank is 0 degree to 45 degrees on a side of an adjacent rack tooth shape and such that an angle formed between the rack tooth shape and an axis of the first rack blank on a side of the respective ends is 5 degrees to 45 degrees. ### Claim 15 (depends on 1) The method according to claim 1, wherein the restraining the first rack blank by the first die comprises restraining the first rack blank by a pair of restraining surfaces of the first die, wherein the pair of restraining surfaces is formed in such a tapered shape that a width between the restraining surfaces continuously decreases toward a direction in which the punch is pressed. ### Claim 16 (depends on 1) The method according to claim 1, wherein the providing the first rack blank and the second rack blank or the mandrel comprises providing the mandrel which is solid and having a cylindrical shape, wherein the surface of the mandrel facing the rack teeth forming portion of the first rack blank is flat along a length the rack teeth forming portion. ### Claim 17 (depends on 1) The method according to claim 1, further comprising: before the restraining the first rack blank by the first die, forming a tapered part on the rack teeth forming portion of the first rack blank. ### Claim 18 (canceled) ### Claim 19 A method of manufacturing a steering rack, the method comprising: providing a first rack blank; forming a tapered part ion a rack teeth forming portion of the first rack blank; and forming rack teeth by pressing a punch having a rack teeth shaped portion onto the rack teeth forming portion of the first rack blank on which the tapered part is formed. ### Claim 20 (canceled) ### Claim 21 (canceled) ### Claim 22 A steering rack comprising: a first rack blank in a form of a pipe having a bore hole; and a second rack blank inserted into the bore hole of the first rack blank, wherein rack teeth are formed on an outer circumferential surface of the first rack blank, and an inner circumferential surface of a rack teeth forming portion of the first rack blank is attached to the second rack blank such that the first rack blank bites into the second rack blank due to plastic deformation. ### Claim 23 (canceled) ### Claim 24 (canceled)