EP0897767A1 - Crémaillère et procédé pour sa fabrication - Google Patents

Crémaillère et procédé pour sa fabrication Download PDF

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Publication number
EP0897767A1
EP0897767A1 EP98115420A EP98115420A EP0897767A1 EP 0897767 A1 EP0897767 A1 EP 0897767A1 EP 98115420 A EP98115420 A EP 98115420A EP 98115420 A EP98115420 A EP 98115420A EP 0897767 A1 EP0897767 A1 EP 0897767A1
Authority
EP
European Patent Office
Prior art keywords
tube
flattened
cylindrical section
rack
flattened portion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98115420A
Other languages
German (de)
English (en)
Inventor
Leonard W. Engler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northrop Grumman Space and Mission Systems Corp
Original Assignee
TRW Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TRW Inc filed Critical TRW Inc
Publication of EP0897767A1 publication Critical patent/EP0897767A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
    • B21K1/767—Toothed racks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
    • B21K1/767—Toothed racks
    • B21K1/768—Toothed racks hollow

Definitions

  • the present invention relates to a steering rack for use in a rack and pinion steering gear, and also relates to a method of manufacturing the rack.
  • a rack and pinion steering gear has a housing containing a rack and a pinion.
  • the rack has a longitudinally extending row of rack teeth in meshing engagement with gear teeth on the pinion.
  • the opposite ends of the rack project outward from the housing, and are connected with a steering linkage and a corresponding pair of steerable vehicle wheels.
  • the pinion is connected with the vehicle steering wheel by an input shaft and a torsion bar. When a steering maneuver is being performed, the pinion rotates, and the rack moves longitudinally.
  • the housing also contains a spring-loaded yoke which presses the rack against the pinion to maintain the rack teeth in meshing engagement with the gear teeth on the pinion.
  • the rack may be manufactured by the use of extruding and broaching processes.
  • the rack may be formed by extruding metal material in the configuration of an elongated tube.
  • the tube has cylindrical inner and outer surfaces.
  • a broaching process is used to form the row of rack teeth.
  • the broaching process first cuts away some of the metal material along a section of the tube to define a planar outer surface which is recessed from the cylindrical outer surface. This reduces the thickness of the metal material along that section of the tube.
  • the broaching process subsequently forms the spaces between the rack teeth by cutting away additional metal material at locations that are evenly spaced apart along the length of the planar surface. As a result, the crests of the rack teeth are defined by the uncut portions of the planar surface that remain between those locations.
  • the present invention comprises a vehicle steering rack and a method of manufacturing the rack.
  • the rack has a flattened portion with a row of rack teeth.
  • the method includes an extruding step and a broaching step, and further includes a swaging step.
  • the method includes the step of extruding a continuous body of material in the configuration of an elongated cylindrical tube.
  • the tube has a first uniform thickness.
  • the swaging step forms a flattened portion of the tube.
  • the flattened portion has a second uniform thickness substantially equal to the first uniform thickness, and has a flattened outer surface.
  • the broaching step forms the rack teeth in a row extending along the flattened portion of the tube by cutting away material at locations that are spaced apart along the flattened outer surface.
  • a steering rack manufactured in accordance with the present invention has increased strength along the row of rack teeth. This is because the swaging step preserves the original extruded thickness of the tube upon forming the flattened portion of the tube. The original extruded thickness, as compared with a reduced thickness, provides the increased strength when the rack teeth have been formed by broaching along the length of the flattened portion of the tube.
  • the swaging step forms a non-cylindrical section of the tube with a triangular cross-sectional configuration.
  • the flattened portion of the tube is one of three flattened portions defining three sides of the non-cylindrical section.
  • a steering rack 10 constructed in accordance with the present invention initially comprises a cylindrical metal tube 12.
  • the tube 12 is formed by extruding metal material through a die. This can be performed in any suitable manner known in the art.
  • the tube 12 is thus formed as a single, continuous body of extruded metal material having a uniform cross-sectional configuration fully along its entire length.
  • the cross-sectional configuration of the tube 12 is defined by cylindrical inner and outer surfaces 14 and 16, each of which is centered on a longitudinal central axis 17.
  • the tube 12 has a uniform thickness T1 (Fig. 2) equal to the difference between the inner and outer diameters at the inner and outer surfaces 14 and 16.
  • the tube 12 of Fig. 1 is swaged to define an elongated, non-cylindrical section 20 of the tube 12, as shown in Fig. 3.
  • the non-cylindrical section 20 in the preferred embodiment of the present invention is spaced from the opposite ends 22 and 24 of the tube 12. Accordingly, the non-cylindrical section 20 is contiguous with an adjacent pair of cylindrical sections 26 and 28 that extend to the opposite ends 22 and 24 of the tube 12.
  • the swaging process is shown schematically in Figs. 5 and 6.
  • Three dies 30 with planar surfaces 32 are used to apply swaging loads to the tube 12 in directions that are offset by 120° about the axis 17, as indicated by the arrows shown in Figs. 5 and 6.
  • the non-cylindrical section 20 of the tube 12 is thus formed with a generally triangular configuration, as shown in Fig. 4, with three flattened side portions 40, 42 and 44 joined by three relatively unflattened corner portions 46.
  • the three flattened side portions 40-44 of the non-cylindrical section 20 are alike. Specifically, each has an inner surface 50 and an outer surface 52.
  • the outer surfaces 52 are planar like the planar die surfaces 32.
  • the inner surfaces 50 are substantially planar as a result of the deflection induced by the dies 30.
  • Each corner portion 46 of the non-cylindrical section 20 also are alike.
  • Each corner portion 46 has an arcuate outer surface 54 defined by a segment of the cylindrical outer surface 16 of the tube 12.
  • Each corner portion 46 further has a narrow arcuate inner surface 56 defined by a segment of the cylindrical inner surface 14 of the tube 12.
  • a broaching process is used to form a longitudinally extending row of rack teeth 60 on the first flattened side portion 40 of the non-cylindrical section 20, as shown in Figs. 7 and 8.
  • the broaching process forms the spaces 62 between the rack teeth 60 by cutting away the metal material at locations that are spaced apart along the outer surface 52 of the first flattened side portion 40.
  • Such a broaching process can be performed in any suitable manner known in the art.
  • the rack teeth 60 in the preferred embodiment of the present invention are thus formed with crests 64 that are defined at least in part by the remaining uncut portions of the outer surface 52.
  • each flattened side portion 40, 42 and 44 of the non-cylindrical section 20 has a substantially uniform thickness T2 (Figs. 4 and 8) between its inner and outer surfaces 50 and 52, and that thickness T2 is substantially equal to the original extruded thickness T1 (Fig. 2) of the tube 12.
  • This feature of the invention maximizes the thickness of the remaining metal material that defines the rack teeth 60 upon completion of the broaching process.
  • the strength of the rack 10 is increased accordingly.
  • the strength of the rack 10 is further increased by the triangular configuration.
  • the rack 10 is installed in a rack and pinion steering gear.
  • a steering gear 70 is shown partially in Fig. 9.
  • the steering gear 70 includes a housing 72 containing the rack 10 and a pinion 74.
  • the pinion 74 has an axis of rotation 75, and has helical gear teeth 76 meshing with the rack teeth 60.
  • the opposite ends of the rack 10 are connected with a vehicle steering linkage and a corresponding pair of steerable vehicle wheels.
  • the pinion 74 is connected with the vehicle steering wheel by an input shaft and a torsion bar, also as known in the art.
  • the pinion 74 rotates about the axis 75, and the rack 10 moves longitudinally along the axis 17.
  • the steering gear 70 further includes a yoke 80.
  • the yoke 80 which is sometimes referred to as a rack guide, has a cylindrical peripheral shape centered on an axis 81 which is perpendicular to the axis 17 of the rack 10.
  • the yoke 80 is contained in a cylindrical section 82 of the housing 72 between a closure cap 84 and the rack 10.
  • a spring 86 is compressed between the yoke 80 and the closure cap 84.
  • the spring 86 applies an axially directed preloading force which urges the yoke 80 forcefully against the rack 10 in a direction extending from left to right, as viewed in Fig. 9.
  • the yoke 80 applies the preloading force to the rack 10 so as to hold the rack teeth 60 firmly in meshing engagement with the gear teeth 76 on the pinion 74.
  • the yoke 80 has a pair of planar guide surfaces 90 which engage the rack 10 in sliding contact at the planar outer surfaces 52 of the second and third flattened side portions 42 and 44. In this configuration, the two pairs of mating surfaces 90 and 52 establish a rotational interlock that blocks movement of the rack 10 rotationally about the axis 17 relative to the pinion 74.
  • the invention relates to a method comprising the steps of: extruding a continuous body of material in the configuration of an elongated cylindrical tube having a first uniform thickness; swaging said tube to form a flattened portion of said tube with a second uniform thickness; broaching said tube to form rack teeth in a row extending along said flattened portion.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transmission Devices (AREA)
EP98115420A 1997-08-19 1998-08-17 Crémaillère et procédé pour sa fabrication Withdrawn EP0897767A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US91858197A 1997-08-19 1997-08-19
US918581 1997-08-19

Publications (1)

Publication Number Publication Date
EP0897767A1 true EP0897767A1 (fr) 1999-02-24

Family

ID=25440614

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98115420A Withdrawn EP0897767A1 (fr) 1997-08-19 1998-08-17 Crémaillère et procédé pour sa fabrication

Country Status (2)

Country Link
EP (1) EP0897767A1 (fr)
JP (1) JPH11151614A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000012245A1 (fr) * 1998-08-29 2000-03-09 Zf Lenksysteme Gmbh Procede de fabrication de cremaillere et dispositif d'estampage permettant la mise en oeuvre dudit procede
EP1092610A3 (fr) * 1999-10-14 2002-12-11 Toyota Jidosha Kabushiki Kaisha Crémaillère et son procédé de fabrication
WO2016017158A1 (fr) * 2014-07-28 2016-02-04 Neturen Co., Ltd. Crémaillère creuse et son procédé de fabrication
CN114954631A (zh) * 2021-02-22 2022-08-30 蒂森克虏伯普利斯坦股份公司 制造机动车转向传动器的齿条的方法、机动车转向传动器的齿条和机动车转向传动器

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100892202B1 (ko) 2007-08-01 2009-04-07 황호진 차량용 중공 스티어링 래크바 및 그 제조방법

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2035507A (en) * 1978-12-11 1980-06-18 Cam Gears Ltd Rack and pinion gear
GB2061138A (en) * 1979-10-24 1981-05-13 Cam Gears Ltd Manufacture of rack member for rack and pinion assembly
JPS58122147A (ja) * 1982-01-14 1983-07-20 Nissan Motor Co Ltd ラツクの成形方法
US4573399A (en) * 1982-07-21 1986-03-04 Cam Gears Limited Piston and cylinder assembly, a power assisted steering gear which includes such an assembly and a method of forming a piston for such an assembly
EP0445470A2 (fr) * 1990-03-08 1991-09-11 Joseph A. Simon Crémaillère allongée à construction légère et procédé de sa fabrication

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2035507A (en) * 1978-12-11 1980-06-18 Cam Gears Ltd Rack and pinion gear
GB2061138A (en) * 1979-10-24 1981-05-13 Cam Gears Ltd Manufacture of rack member for rack and pinion assembly
JPS58122147A (ja) * 1982-01-14 1983-07-20 Nissan Motor Co Ltd ラツクの成形方法
US4573399A (en) * 1982-07-21 1986-03-04 Cam Gears Limited Piston and cylinder assembly, a power assisted steering gear which includes such an assembly and a method of forming a piston for such an assembly
EP0445470A2 (fr) * 1990-03-08 1991-09-11 Joseph A. Simon Crémaillère allongée à construction légère et procédé de sa fabrication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 007, no. 230 (M - 249) 12 October 1983 (1983-10-12) *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000012245A1 (fr) * 1998-08-29 2000-03-09 Zf Lenksysteme Gmbh Procede de fabrication de cremaillere et dispositif d'estampage permettant la mise en oeuvre dudit procede
US6601428B1 (en) 1998-08-29 2003-08-05 Zf Lenksysteme Gmbh Method for producing a gear rack, and a stamping device for carrying out the method
EP1092610A3 (fr) * 1999-10-14 2002-12-11 Toyota Jidosha Kabushiki Kaisha Crémaillère et son procédé de fabrication
WO2016017158A1 (fr) * 2014-07-28 2016-02-04 Neturen Co., Ltd. Crémaillère creuse et son procédé de fabrication
KR20170038841A (ko) * 2014-07-28 2017-04-07 고오슈우하네쓰렌 가부시기가이샤 중공형 랙바 및 중공형 랙바를 제조하는 방법
CN106660108A (zh) * 2014-07-28 2017-05-10 高周波热炼株式会社 空心齿条杆及其制造方法
US10449995B2 (en) 2014-07-28 2019-10-22 Neturen Co., Ltd. Hollow rack bar and method of manufacturing the hollow rack bar
CN114954631A (zh) * 2021-02-22 2022-08-30 蒂森克虏伯普利斯坦股份公司 制造机动车转向传动器的齿条的方法、机动车转向传动器的齿条和机动车转向传动器

Also Published As

Publication number Publication date
JPH11151614A (ja) 1999-06-08

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