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WO2018193919A1 - Arbre de crémaillère et procédé pour fabriquer un arbre de crémaillère - Google Patents

Arbre de crémaillère et procédé pour fabriquer un arbre de crémaillère Download PDF

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Publication number
WO2018193919A1
WO2018193919A1 PCT/JP2018/015117 JP2018015117W WO2018193919A1 WO 2018193919 A1 WO2018193919 A1 WO 2018193919A1 JP 2018015117 W JP2018015117 W JP 2018015117W WO 2018193919 A1 WO2018193919 A1 WO 2018193919A1
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WO
WIPO (PCT)
Prior art keywords
shaft
rack
rack teeth
crushing
teeth
Prior art date
Application number
PCT/JP2018/015117
Other languages
English (en)
Japanese (ja)
Inventor
真楽 吉川
井出　典数
Original Assignee
Ｋｙｂ株式会社
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 Ｋｙｂ株式会社 filed Critical Ｋｙｂ株式会社
Publication of WO2018193919A1 publication Critical patent/WO2018193919A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/12—Forming profiles on internal or external surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/08—Upsetting
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23F—MAKING GEARS OR TOOTHED RACKS
    • B23F1/00—Making gear teeth by tools of which the profile matches the profile of the required surface
    • B23F1/08—Making gear teeth by tools of which the profile matches the profile of the required surface by broaching; by broach-milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23F—MAKING GEARS OR TOOTHED RACKS
    • B23F5/00—Making straight gear teeth involving moving a tool relatively to a workpiece with a rolling-off or an enveloping motion with respect to the gear teeth to be made
    • B23F5/20—Making straight gear teeth involving moving a tool relatively to a workpiece with a rolling-off or an enveloping motion with respect to the gear teeth to be made by milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23F—MAKING GEARS OR TOOTHED RACKS
    • B23F5/00—Making straight gear teeth involving moving a tool relatively to a workpiece with a rolling-off or an enveloping motion with respect to the gear teeth to be made
    • B23F5/28—Making straight gear teeth involving moving a tool relatively to a workpiece with a rolling-off or an enveloping motion with respect to the gear teeth to be made by broaching; by broach-milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D3/00—Steering gears
    • B62D3/02—Steering gears mechanical
    • B62D3/12—Steering gears mechanical of rack-and-pinion type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/26—Racks

Definitions

  • the present invention relates to a rack shaft and a method for manufacturing the rack shaft.
  • a dual pinion type electric power steering device in which steering torque by a driver and steering assist torque by an electric motor are independently input to a rack shaft is known.
  • a dual pinion type electric power steering apparatus it has been proposed to reduce the weight by forming a rack shaft from a hollow or cylindrical member (JP 2004-523365A, JP 2014-124767A).
  • first rack teeth are formed on a hollow first bar by forging.
  • a hollow second shaft is joined to the first shaft by friction welding, and second rack teeth are formed on the second shaft by cutting.
  • both the first and second rack teeth are formed by forging.
  • the shaft In the forging process, the shaft is plastically deformed according to the pressure applied to the shaft. Therefore, in order to form rack teeth, it is necessary to apply a large pressure to the shaft, and when the pressure is applied to the shaft, the shaft may rotate around the axis with respect to the mold. If the shaft rotates about the axis with respect to the mold at the time of forming the second rack tooth, the phase angle of the second rack tooth with respect to the first rack tooth shifts, and the phase angle accuracy of the first rack tooth and the second rack tooth decreases. To do.
  • the second rack teeth are formed by cutting a second shaft whose outer surface and inner surface are circular. Therefore, the thickness between the bottom of the second rack teeth and the inner surface of the second shaft decreases from the end in the tooth width direction of the second rack teeth toward the center, and the strength at the center is the lowest. If the second shaft is made thicker in order to increase the strength at the central portion, the portion other than the central portion becomes thicker than necessary, and the weight of the rack shaft increases.
  • An object of the present invention is to reduce the weight of the rack shaft while improving the phase angle accuracy of the first rack teeth and the second rack teeth.
  • the present invention relates to a rack shaft that converts the rotational motion of the first and second pinion gears into a linear motion.
  • the rack shaft includes a hollow shaft body, and first and second rack teeth provided on the shaft body and meshing with the first and second pinion gears, respectively.
  • the crushed portion is formed by crushing in the radial direction and includes a flat portion on the outer surface, and at least one of the first and second rack teeth is formed in the crushed portion by cutting.
  • a method for manufacturing a rack shaft includes a first rack tooth forming step for forming a first rack tooth on a hollow shaft body, and a second rack tooth for forming a second rack tooth on the shaft body. And forming a crushing portion including a flat portion on the outer surface by crushing the shaft main body in the radial direction, and crushing after forming the first rack teeth. Forming a second rack tooth on the part by cutting.
  • FIG. 1 is a configuration diagram of an electric power steering apparatus including a rack shaft according to the first embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of the rack shaft according to the first embodiment of the present invention.
  • 3A is a cross-sectional view taken along line IIIA-IIIA shown in FIG. 3B is a cross-sectional view taken along line IIIB-IIIB shown in FIG. 4A.
  • 3C is a cross-sectional view taken along the line IIIC-IIIC shown in FIG.
  • FIG. 4A is a view for explaining a method of manufacturing the rack shaft shown in FIG. 2, and shows a step of forming a first crushing portion in the shaft body.
  • FIG. 4B is a view for explaining a method of manufacturing the rack shaft shown in FIG.
  • FIG. 5 is a cross-sectional view of a rack shaft according to the second embodiment of the present invention, corresponding to FIG.
  • FIG. 6A is a diagram for explaining a method of manufacturing the rack shaft shown in FIG. 5 and shows a step of forming first rack teeth on the shaft body.
  • FIG. 6B is a view for explaining a method of manufacturing the rack shaft shown in FIG. 5 and shows a step of forming a crushing portion in the shaft body.
  • FIG. 7 is a cross-sectional view of a rack shaft according to the third embodiment of the present invention, corresponding to FIG.
  • FIG. 8A is a cross-sectional view showing a modified example of the crushed portion, and corresponds to FIG. 3C.
  • FIG. 8B is a cross-sectional view showing another modified example of the crushed portion, corresponding to FIG. 3C.
  • FIG. 9 is a cross-sectional view of a rack shaft according to a comparative example, corresponding to FIG. 3C.
  • FIG. 1 is a configuration diagram of an electric power steering apparatus 100 including a rack shaft 50 according to the first embodiment of the present invention.
  • the electric power steering device 100 is a dual pinion type electric power steering device in which the steering force by the driver and the assist driving force by the electric motor 21 are independently input to the rack shaft 50.
  • the electric power steering apparatus 100 includes a steering mechanism 10 that steers the wheels 2 of the vehicle according to the rotation of the steering wheel 1 to which the steering force is input by the driver, and an assist mechanism 20 that assists the driver's steering force. And a control device 30 for controlling the assist amount of the steering force.
  • the steering mechanism 10 includes a steering shaft 11 that is connected to the steering wheel 1 and rotates according to the rotation of the steering wheel 1, and a rack shaft 50 that steers the vehicle wheel 2 according to the rotation of the steering shaft 11. .
  • the rack shaft 50 is connected to the wheel 2 via the tie rod 3.
  • the steering shaft 11 has an input shaft 13 connected to the steering wheel 1 and an output shaft 15 connected to the input shaft 13 via a torsion bar 14.
  • the output shaft 15 is provided with a first pinion gear 16 that meshes with the rack shaft 50.
  • the assist mechanism 20 includes an electric motor 21 that is a power source of assist force, a worm shaft 22 that is coupled to the output shaft of the electric motor 21, a worm wheel 23 that meshes with the worm shaft 22, and a pinion that is coupled to the worm wheel 23. And a shaft 24.
  • the pinion shaft 24 is provided with a second pinion gear 25 that meshes with the rack shaft 50.
  • the control device 30 includes a torque sensor 31 that detects the steering torque applied to the torsion bar 14 based on the relative rotation between the input shaft 13 and the output shaft 15, and a rotation angle sensor 32 that detects the rotation angle of the pinion shaft 24.
  • the steering angle sensor 34 that detects the rotation angle (steering angle) of the steering wheel 1, the motor rotation angle sensor 35 that is configured by a resolver and detects the rotation angle of the electric motor 21, and the controller 33 that controls the operation of the electric motor 21. And having.
  • the controller 33 controls the driving of the electric motor 21 based on the steering torque detected by the torque sensor 31 and the rotation angle of the electric motor 21 detected by the motor rotation angle sensor 35.
  • the controller 33 may control the driving of the electric motor 21 in consideration of the steering angle detected by the steering angle sensor 34 in addition to the steering torque and the rotation angle of the electric motor 21. Further, the controller 33 may control the driving of the electric motor 21 in consideration of the rotation angle of the pinion shaft 24 detected by the rotation angle sensor 32.
  • the rotation angle of the pinion shaft 24 detected by the rotation angle sensor 32 is used, the turning angle of the wheel 2 can be accurately grasped.
  • the detection result of the rotation angle sensor 32 is also used in control of a VDC (Vehicle Dynamics Control) or the like that suppresses a side slip or the like of the vehicle.
  • VDC Vehicle Dynamics Control
  • the rack shaft 50 includes a shaft main body 51 and first and second rack teeth 52 and 53 provided on the outer periphery of the shaft main body 51.
  • the first rack teeth 52 mesh with the first pinion gear 16 of the output shaft 15, and the second rack teeth 53 mesh with the second pinion gear 25 of the pinion shaft 24.
  • the shaft body 51 is connected to the wheel 2 via the tie rod 3.
  • Rotational force of the steering wheel 1 is transmitted to the output shaft 15 via the input shaft 13 and the torsion bar 14.
  • the rotational force of the output shaft 15 is converted into a force in the axial direction of the rack shaft 50 (the left-right direction of the vehicle) via the first pinion gear 16 and transmitted to the rack shaft 50. For this reason, when the steering wheel 1 is steered, the rack shaft 50 moves in the axial direction, and the vehicle wheel 2 is snaked according to the movement of the rack shaft 50.
  • Rotational force of the electric motor 21 is transmitted to the pinion shaft 24 via the worm shaft 22 and the worm wheel 23.
  • the rotational force of the pinion shaft 24 is converted into a force in the axial direction of the rack shaft 50 (the left-right direction of the vehicle) and transmitted to the rack shaft 50. For this reason, when the electric motor 21 is rotationally driven, a steering assist thrust is applied to the rack shaft 50 and the steering of the steering wheel 1 is assisted.
  • the rack shaft 50 is formed from a metal material (for example, carbon steel). As shown in FIG. 2, the shaft body 51 of the rack shaft 50 is formed in a hollow shape.
  • the shaft body 51 may be formed as a single hollow member that does not include a joint portion, or may be formed by joining a plurality of hollow members. When the rack shaft 50 is formed as one hollow member that does not include a joint portion, it is easy to ensure the coaxiality of the rack shaft 50.
  • a seamless tube or an electric resistance tube can be used as the hollow member that does not include the joint portion. Since the seamless pipe and the electric resistance welded pipe do not include the joint portion, the joining work can be omitted. Furthermore, you may perform processes, such as a swaging process and a drawing process, to a seamless pipe or an electric sewing pipe.
  • the shaft body 51 includes first and second crushing parts 54 and 55 having flat parts 54a and 55a on the outer surface, and an intermediate part 56 provided between the first and second crushing parts 54 and 55. As shown in FIG. 3A, the outer surface and the inner surface of the intermediate portion 56 are formed in a circular shape. As shown in FIG. 2, the 1st and 2nd rack teeth 52 and 53 are formed in the 1st and 2nd crushing parts 54 and 55, respectively.
  • the first crushing portion 54 is formed by crushing a part of the material of the shaft main body 51 whose entire length is formed in a cylindrical shape in the radial direction. Specifically, first, the outer surface of the material of the shaft body 51 is sandwiched between the upper mold 61 and the lower mold 62 of the processing machine 60. Next, the pressing die 63 is inserted into the guide hole 61 a of the upper die 61 to crush a part of the material of the shaft body 51 in the radial direction. Thereby, the first crushing portion 54 is formed in the shaft main body 51. Since a part of the shaft body 51 is crushed to form the first crushed portion 54, a flat portion 54a is formed on the outer surface of the first crushed portion 54 as shown in FIG. 3B.
  • the mandrel 64 When forming the first crushing portion 54, the mandrel 64 is inserted into the shaft body 51 as shown in FIG. 4A. A flat portion 64 a is formed on the outer surface of the mandrel 64, and the pressing die 63 crushes the shaft body 51 toward the flat portion 64 a of the mandrel 64. Therefore, as shown in FIG. 3B, a flat portion 54 b is formed on the inner surface of the first squashed portion 54. Since the flat portions 54a and 54b are formed on the outer and inner surfaces of the first squashed portion 54, the first squashed portion 54 has a uniform thickness.
  • the second crushing portion 55 is formed by crushing a part of the material of the shaft body 51 formed in a cylindrical shape in the radial direction, like the first crushing portion 54. Therefore, flat portions 55a and 55b are formed on the outer surface and the inner surface of the second crushed portion 55 similarly to the first crushed portion 54, and the second crushed portion 55 has a uniform thickness.
  • the first rack teeth 52 are formed in the first crushing portion 54 by cutting. Specifically, a part of the 1st crushing part 54 is cut using the broaching board 70, and a some groove
  • the width of the flat portion 54 a of the first crushing portion 54 corresponds to the tooth width L ⁇ b> 1 of the first rack tooth 52.
  • the depth of the groove formed in the first crushing portion 54 by the cutting process corresponds to the tooth height L ⁇ b> 2 of the first rack tooth 52.
  • the bottom surface of the groove formed in the first crushing portion 54 by cutting is a tooth bottom 52 a of the first rack tooth 52.
  • the tooth tips of the first rack teeth 52 may be further cut.
  • the width of the flat portion 54 a after cutting corresponds to the tooth width L 1 of the first rack tooth 52.
  • the cutting resistance can be reduced by controlling the cutting allowance, the force applied to the shaft main body 51 compared to the case where the first rack teeth 52 are formed by plastic deformation. Can be reduced. Therefore, the shaft body 51 can be prevented from moving with respect to the broaching machine 70 during the cutting process, and the first rack teeth 52 can be formed at a desired phase angle.
  • a flat portion 54 b is formed on the inner surface of the first squashed portion 54. Therefore, the thickness between the bottom 52a of the first rack tooth 52 and the inner surface of the first crushed part 54 is formed by cutting the first crushed part 54 along the flat part 54b to form the first rack tooth 52.
  • L3 is substantially uniform in the tooth width direction of the first rack teeth 52.
  • FIG. 9 is a cross-sectional view of the rack shaft 450, corresponding to FIG. 3C.
  • the first rack teeth 452 are formed by cutting a material of the shaft body 451 whose outer surface and inner surface are circular. Specifically, first, a cutting portion 454 having a flat portion 454a on the outer surface is formed on the material of the shaft body 451 by cutting. Thereafter, a plurality of grooves are formed in the cutting portion 454 by cutting. Thereby, the first rack teeth 452 are formed. Therefore, the width of the flat portion 454a of the cutting portion 454 corresponds to the tooth width L21 of the first rack tooth 452. Further, the depth of the groove formed in the cutting part 454 corresponds to the tooth height L22 of the first rack tooth 452.
  • the thickness between the bottom 452a of the first rack tooth 452 and the inner surface of the shaft main body 451 is the tooth width direction of the first rack tooth 452. It decreases as it goes from both ends to the central portion 452b. That is, the thickness L23 at the central portion 452b is the smallest.
  • the strength of the first rack teeth 452 depends on the thickness between the tooth bottom 452a and the inner surface of the shaft body 451. In order to give the first rack teeth 452 a desired strength, it is necessary to determine the inner diameter D2 of the shaft body 451 in accordance with the thickness L23 in the central portion 452b. Accordingly, in a portion other than the central portion 452b, the thickness between the bottom 452a of the first rack tooth 452 and the inner surface of the shaft body 451 becomes thicker than necessary.
  • the first crushed portion 54 is cut in a state where the flat portion 54 b is formed on the inner surface of the first crushed portion 54. Therefore, the inner diameter D1 of the shaft body 51 is determined in accordance with the thickness L3 at the edge 54c of the flat portion 54b of the first crushed portion 54, whereby the inner surface of the first crushed portion 54 and the entire edge 54c of the flat portion 54b.
  • the strength of the first rack teeth 52 can be increased without making the gap between the first rack teeth 52 and the root 52a unnecessarily thick. Accordingly, the inner diameter D1 of the material of the shaft main body 51 can be increased to make the shaft main body 51 thinner, and the rack shaft 50 can be reduced in weight.
  • the second rack teeth 53 are formed in the second crushing portion 55 by cutting using a broaching machine 70 (see FIG. 4C), similarly to the first rack teeth 52.
  • the cutting resistance can be reduced by controlling the cutting allowance, so that the force applied to the shaft main body 51 compared to the case where the second rack teeth 53 are formed by plastic deformation. Can be reduced. Therefore, it is possible to prevent the shaft body 51 from rotating around the axis with respect to the broaching machine 70 during the cutting process. Accordingly, when the second rack teeth 53 are formed after the first rack teeth 52 are formed, the second rack teeth 53 can be formed with a desired phase difference with respect to the first rack teeth 52.
  • the second crushing part 55 is cut with the flat part 55b formed on the inner surface of the second crushing part 55. Therefore, similarly to the first rack teeth 52, the strength of the first rack teeth 52 is increased without increasing the thickness between the inner surface of the second crushing portion 55 and the tooth bottom 53a of the second rack teeth 53 more than necessary. be able to. Accordingly, the inner diameter D1 of the material of the shaft main body 51 can be increased to make the shaft main body 51 thinner, and the rack shaft 50 can be reduced in weight.
  • the first and second rack teeth 52, 53 are formed by cutting the first and second crushing portions 54, 55, respectively, the first and second rack teeth 52, 53 are connected to a common broach. It can be molded using the board 70. Therefore, the manufacturing cost of the rack shaft 50 can be reduced.
  • the first and second rack teeth 52 and 53 are formed.
  • the second crushing portion 55 may be formed to form the second rack teeth 53.
  • the second rack teeth 53 are formed on the second crushing portion 55 by cutting.
  • the cutting resistance can be reduced by controlling the cutting allowance, so that the force applied to the shaft main body 51 compared to the case where the second rack teeth 53 are formed by plastic deformation. Can be reduced. Therefore, the shaft body 51 can be prevented from rotating around the axis during cutting. Therefore, by forming the second rack teeth 53 after forming the first rack teeth 52, the second rack teeth 53 can be formed with a desired phase difference with respect to the first rack teeth 52. The phase angle accuracy of the teeth 52 and the second rack teeth 53 can be improved.
  • the second crushing portion 55 is formed by crushing the shaft body 51 in the radial direction. Therefore, the inner surface of the second crushing portion 55 is deformed inward in the radial direction of the shaft body 51. Therefore, the shaft body 51 can be thinned while increasing the strength of the second rack teeth 53 formed by cutting the second crushing portion 55, and the rack shaft 50 can be reduced in weight.
  • the second crushing portion 55 has a uniform thickness. For this reason, the gap between the inner surface of the second crushing portion 55 and the root 53a of the second rack tooth 53 is not made thicker than necessary over the entire width between both edges of the flat portion 55b in the tooth width direction of the second rack tooth 53. The strength of the second rack teeth 53 can be increased. Therefore, the rack shaft 50 can be reduced in weight.
  • both the first and second rack teeth 52 and 53 are formed in the first and second crushing portions 54 and 55 by cutting. Therefore, both the first and second rack teeth 52 and 53 can be formed using the common broaching machine 70, and the manufacturing cost of the rack shaft 50 can be reduced.
  • a rack shaft 250 according to a second embodiment of the present invention will be described with reference to FIGS. 5, 6A, and 6B.
  • differences from the first embodiment will be mainly described.
  • the same or corresponding components as those described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
  • the electric power steering apparatus including the rack shaft 250 is substantially the same as the electric power steering apparatus 100 shown in FIG. 1, the description and illustration thereof are omitted here.
  • the rack shaft 250 includes a hollow shaft body 51 and first and second rack teeth 252 and 53 formed on the outer periphery of the shaft body 251.
  • the first rack teeth 252 are formed by forging on a part of the material of the shaft body 51 whose overall length is formed in a cylindrical shape. Specifically, as shown in FIG. 6A, first, the outer surface of the shaft body 51 before processing is sandwiched between the upper mold 81 and the lower mold 82 of the forging machine 80 and the mandrel 84 is inserted into the shaft body 51. To do. Next, the forging die 83 is inserted into the guide hole 81 a of the upper die 81 to crush the shaft body 51. Thereby, a part of the shaft body 51 is plastically deformed, and the first rack teeth 252 are formed.
  • the first rack teeth 252 are formed according to the shape of the forging die 83. Therefore, the first rack teeth 252 can be formed in a complicated shape such as VGR (Variable Gear Ratio).
  • the second rack teeth 53 are formed in the second crushing portion 55 by cutting. Specifically, after the first rack teeth 252 are formed by forging, the outer surface of the shaft body 51 is sandwiched between the upper mold 61 and the lower mold 62 of the processing machine 60. Next, the pressing die 63 is inserted into the guide hole 61 a of the upper die 61 to crush the shaft body 51. Thereby, the 2nd crushing part 55 is formed. Thereafter, a part of the second crushing portion 55 is cut to form a plurality of grooves. Thereby, the 2nd rack tooth
  • the first rack teeth 252 are formed by forging. Therefore, the first rack teeth 252 can be formed according to the shape of the forging die 83, and the rack shaft 250 having the rack teeth having a complicated shape such as VGR can be easily manufactured. Further, since the second rack teeth 53 are formed in the second crushing portion 55 by cutting, the second rack teeth 53 have a desired phase difference with respect to the first rack teeth 252 having a complicated shape previously formed on the shaft body 51 by forging. The rack shaft 250 can be reduced in weight while forming the second rack teeth 53.
  • a rack shaft 350 according to a third embodiment of the present invention will be described with reference to FIG.
  • differences from the first and second embodiments will be mainly described, and in the figure, the same or corresponding configurations as those described in the first and second embodiments are denoted by the same reference numerals. Description is omitted.
  • the electric power steering apparatus including the rack shaft 350 is substantially the same as the electric power steering apparatus 100 shown in FIG. 1, the description and illustration thereof are omitted here.
  • the shaft main body 351 of the rack shaft 350 includes a hollow first shaft portion 351a having a predetermined thickness t1, and a second shaft portion 351b in which the thickness t2 is thicker than the thickness t1 of the first shaft portion 351a. And having.
  • the first shaft portion 351a and the second shaft portion 351b are joined together and formed as an integrated hollow member.
  • the first shaft portion 351a and the second shaft portion 351b are joined by, for example, friction welding.
  • the first rack teeth 252 are formed on the first shaft portion 351a by forging. Since the thickness of the first shaft portion 351a is thin, the first shaft portion 351a can be easily plastically deformed by forging. Therefore, the first rack teeth 252 can be easily formed.
  • the second crushing portion 55 is formed on the second shaft portion 351b, and the second rack teeth 53 are formed on the second crushing portion 55 by cutting. Since the thickness of the 2nd shaft part 351b is thick, the thickness of the 2nd crushing part 55 can be thickened, and the intensity
  • the first and second rack teeth 252 and 53 are formed by a processing method suitable for the first and second shaft portions 351a and 351b having different thicknesses. Therefore, an increase in the weight of the rack shaft 350 can be reduced and the rack shaft 350 can be easily manufactured.
  • the rack shaft 350 by forming the first rack teeth 252 on the first shaft portion 351a and then forming the second rack teeth 53, the first rack teeth 252 having a complicated shape formed by the forging process can be obtained.
  • the rack shaft 250 can be reduced in weight while forming the second rack teeth 53 with a desired phase difference.
  • the second crushing portion 55 is formed by inserting the mandrel 64 into the shaft main body 51 and crushing the shaft main body 51 in the radial direction. Is formed with a flat portion 55b.
  • the present invention is not limited to this, and the second squashed part 55 may be formed in a state where the mandrel 64 is not inserted into the shaft body 51, and the flat part 55 b is formed on the inner surface of the second squashed part 55. It does not have to be.
  • the inner surface of the second crushing portion 55 may protrude or protrude toward the radially inner side of the shaft body 51.
  • the inner surface of the second crushing portion 55 may be recessed toward the radially outer side of the shaft body 51. That is, the inner surface of the second crushed portion 55 only needs to be deformed radially inward and crushed as compared with the shapes of the inner surfaces of the shaft bodies 51 and 351 before processing.
  • the inner surface of the first crushed portion 54 may be crushed as compared with the shapes of the inner surfaces of the shaft main bodies 51 and 351 before processing.
  • the width of the flat portion 55a of the second crushing portion 55 is smaller than the outer diameter of the shaft bodies 51 and 351.
  • This invention is not limited to this, You may form the 2nd crushing part 55 so that the width
  • the first crushed portion 54 is formed so that the width of the flat portion 54a of the first crushed portion 54 is equal to or larger than the outer diameter of the shaft body 51 before processing, and the tooth width of the first rack teeth 52 is increased. Also good.
  • the second crushing portion 55 has substantially the same thickness as that of the shaft bodies 51 and 351 before processing.
  • This invention is not limited to this, You may form the 2nd crushing part 55 so that the thickness of the flat part 55a of the 2nd crushing part 55 may become thicker than the thickness of the shaft main bodies 51 and 351 before a process. In this case, the tooth height of the second rack teeth 53 can be increased.
  • the first crushing part 54 is formed so that the thickness of the flat part 54a of the first crushing part 54 is thicker than the thickness of the shaft body 51 before processing, and the tooth height of the first rack teeth 52 is increased. Also good.
  • a flat portion may be formed in a region other than the first and second rack teeth 52, 53, 252 on the outer surfaces of the shaft bodies 51, 351. By bringing a pressure pad (not shown) into contact with such a flat portion, the rotation of the rack shafts 50, 250, and 350 can be regulated.
  • Such flat portions may be formed over the entire length of the shaft bodies 51 and 351, or may be formed only in the vicinity of the first rack teeth 52 and 252 or the second rack teeth 53.
  • the first rack teeth 52 and 252 and the second rack teeth 53 are formed in the same phase, but the first rack teeth 52 and 252 and the second rack teeth 53 are formed in different phases. May be.
  • the first rack teeth 52 and 252 mesh with the first pinion gear 16 of the output shaft 15 and the second rack teeth 53 mesh with the second pinion gear 25 of the pinion shaft 24.
  • the invention is not limited to this form.
  • the first rack teeth 52 and 252 may mesh with the second pinion gear 25 of the pinion shaft 24, and the second rack teeth 53 may mesh with the first pinion gear 16 of the output shaft 15.
  • the rotational force of the steering wheel 1 is transmitted to the rack shafts 50, 250, 350 via the second rack teeth 53
  • the rotational force of the electric motor 21 is transmitted to the rack shafts 50, 250 via the first rack teeth 52, 252. , 350 may be transmitted.
  • This embodiment relates to rack shafts 50, 250, and 350 that convert the rotational motions of the first and second pinion gears 16 and 25 into linear motions.
  • the rack shafts 50, 250, 350 are provided in the hollow shaft main bodies 51, 351 and the shaft main bodies 51, 351, and the first and second rack teeth 52, 53 that mesh with the first and second pinion gears 16, 25, respectively.
  • , 252 and the shaft main bodies 51, 351 are formed by crushing in the radial direction and have first and second crushing portions 54, 55 including flat portions 54 a, 55 a on the outer surface. Is formed in the second crushing portion 55 by cutting.
  • the second rack teeth 53 are formed in the second crushing portion 55 by cutting.
  • the cutting resistance can be reduced by controlling the cutting allowance, and therefore, in addition to the case where the second rack teeth 53 are formed by plastic deformation, in addition to the shaft main bodies 51 and 351.
  • the force that can be reduced can be reduced. Therefore, it is possible to prevent the shaft bodies 51 and 351 from rotating around the axis during cutting. Therefore, by forming the second rack teeth 53 after forming the first rack teeth 52 and 252, the second rack teeth 53 can be formed with a desired phase difference with respect to the first rack teeth 52 and 252.
  • the second crushing portion 55 is formed by crushing the shaft main bodies 51 and 351 in the radial direction.
  • the shaft main body 51 can be made thin while increasing the strength of the second rack teeth 53 formed by cutting the second crushing portion 55. Accordingly, the rack shafts 50, 250, and 350 can be reduced in weight while improving the phase angle accuracy of the first rack teeth 52 and the second rack teeth 53.
  • the first and second crushing parts 54 and 55 have a uniform thickness.
  • the second crushing portion 55 has a uniform thickness. Therefore, the second rack without increasing the thickness between the inner surface of the second crushed portion 55 and the bottom 53a of the second rack tooth 53 over the entire length between both edges 55c of the flat portion 55b of the second crushed portion 55.
  • the strength of the teeth 53 can be increased. Therefore, the rack shafts 50, 250, and 350 can be reduced in weight.
  • the first and second rack teeth 52, 53 are formed in the first and second crushing portions 54, 55 by cutting.
  • the first and second rack teeth 52 and 53 are formed in the first and second crushing portions 54 and 55 by cutting. Therefore, both the first and second rack teeth 52 and 53 can be formed using the common broaching machine 70, and the manufacturing cost of the rack shaft 50 can be reduced.
  • the first rack teeth 252 are formed on the shaft bodies 51 and 351 by forging, and the second rack teeth 53 are formed on the second crushing portion 55 by cutting.
  • the first rack teeth 252 are formed by forging. Therefore, the first rack teeth 252 can be formed according to the shape of the forging die 83, and the rack shafts 250 and 350 having the first rack teeth 252 having a complicated shape such as VGR (Variable Gear Ratio) can be easily obtained. Can be manufactured. Further, since the second rack teeth 53 are formed in the second crushing portion 55 by cutting, a desired phase difference with respect to the first rack teeth 252 having a complicated shape previously formed on the shaft body 351 by forging. The rack shafts 250 and 350 can be reduced in weight while forming the second rack teeth 53.
  • VGR Very Gear Ratio
  • the shaft body 351 has a first shaft portion 351a and a second shaft portion 351b having a thickness t2 larger than the thickness t1 of the first shaft portion 351a, and the first rack teeth 252 are
  • the second crushing portion 55 is provided on the second shaft portion 351b.
  • the first shaft portion 351a since the thickness t1 of the first shaft portion 351a is thin, the first shaft portion 351a can be easily plastically deformed by forging, and the first rack teeth 252 can be easily formed.
  • the 2nd crushing part 55 is provided in the 2nd shaft part 351b which has thick thickness t2. Therefore, the strength of the second crushed portion 55 can be increased, and damage to the second crushed portion 55 when the second rack teeth 53 are formed by cutting can be prevented. Therefore, the rack shaft 350 can be easily manufactured.
  • the shaft main bodies 51 and 351 are formed of one hollow member that does not include a joint portion.
  • the shaft main bodies 51 and 351 are formed of one hollow member that does not include a joint portion.
  • a hollow member that does not include a joint portion for example, a seamless tube or an electric sewing tube can be used. Since the seamless pipe and the electric resistance welded pipe do not include the joint portion, the joining work can be omitted.
  • the present embodiment relates to a method of manufacturing the rack shafts 50, 250, 350 including the first and second rack teeth 52, 53, 252 that mesh with the first and second pinion gears 16, 25, respectively.
  • the manufacturing method of the rack shafts 50, 250, and 350 includes a first rack tooth forming step of forming the first rack teeth 52 and 252 on the hollow shaft main bodies 51 and 351, and the second rack teeth 53 on the shaft main bodies 51 and 351.
  • a second rack tooth forming step wherein the second rack tooth forming step includes crushing the shaft bodies 51 and 351 in the radial direction to form the second crushing portion 55, and the first rack teeth 52, Forming the second rack teeth 53 on the second crushing portion 55 by cutting after the 252 is formed.
  • the second rack teeth 53 are formed on the second crushing portion 55 by cutting.
  • the shaft main bodies 51 and 351 can be prevented from rotating around the axis during the cutting process, and the second rack teeth 53 can be formed with a desired phase difference with respect to the first rack teeth 52 and 252.
  • the second crushing portion 55 is formed by crushing the shaft main bodies 51 and 351 in the radial direction. Therefore, the inner surface of the second crushing portion 55 is deformed radially inward of the shaft main bodies 51 and 351.
  • the shaft main bodies 51 and 351 can be thinned while increasing the strength of the second rack teeth 53.
  • the rack shafts 50, 250, 350 can be reduced in weight while improving the phase angle accuracy of the first rack teeth 52, 252 and the second rack teeth 53.
  • the first rack tooth forming step includes forming the first rack teeth 52 and 252 on the shaft bodies 51 and 351 by forging.
  • the first rack teeth 252 are formed by forging. Therefore, the first rack teeth 252 can be formed according to the shape of the forging die 83, and the rack shafts 250 and 350 having the first rack teeth 252 having a complicated shape such as VGR (Variable Gear Ratio) can be easily obtained. Can be manufactured.
  • VGR Variable Gear Ratio
  • the second rack teeth 53 are formed on the second crushing portion 55 after the first rack teeth 252 are formed by forging, a desired position is obtained with respect to the first rack teeth 252 having a complicated shape.
  • the rack shafts 250 and 350 can be reduced in weight while forming the second rack teeth 53 by the phase difference.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Gears, Cams (AREA)
  • Power Steering Mechanism (AREA)
  • Forging (AREA)

Abstract

L'invention concerne un arbre de crémaillère (50), lequel arbre comporte : un corps d'arbre creux (51) ; et des premières et secondes dents de crémaillère (52, 53) s'engrenant respectivement avec des premier et second pignons (16, 25). Le corps d'arbre (51) a une seconde section comprimée (55) qui est formée de façon radialement comprimée et qui comprend une section plate (55a) sur la surface externe de celle-ci. Les secondes dents de crémaillère (53) sont formées par découpe sur la seconde section comprimée (55).
PCT/JP2018/015117 2017-04-21 2018-04-10 Arbre de crémaillère et procédé pour fabriquer un arbre de crémaillère WO2018193919A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017084646A JP6748600B2 (ja) 2017-04-21 2017-04-21 ラックシャフト及びラックシャフトの製造方法
JP2017-084646 2017-04-21

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WO2018193919A1 true WO2018193919A1 (fr) 2018-10-25

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7369661B2 (ja) * 2020-04-24 2023-10-26 株式会社日立インダストリアルプロダクツ 回転子のシャフト交換方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS603172U (ja) * 1983-06-22 1985-01-11 トヨタ自動車株式会社 ラツクアンドピニオン型ステアリングギアのラツクバ−
JPH05345231A (ja) * 1992-06-15 1993-12-27 Sumitomo Metal Ind Ltd ラックチューブの製造方法
KR100799935B1 (ko) * 2006-11-27 2008-01-31 주식회사 코우 랙바아의 랙성형방법
JP2014124767A (ja) * 2012-12-27 2014-07-07 Neturen Co Ltd ラック製造装置及びラック製造方法
JP2014214810A (ja) * 2013-04-25 2014-11-17 高周波熱錬株式会社 ダブルピニオン式ラックバー

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009000734A (ja) * 2007-06-25 2009-01-08 Nsk Ltd ラック及びその製造方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS603172U (ja) * 1983-06-22 1985-01-11 トヨタ自動車株式会社 ラツクアンドピニオン型ステアリングギアのラツクバ−
JPH05345231A (ja) * 1992-06-15 1993-12-27 Sumitomo Metal Ind Ltd ラックチューブの製造方法
KR100799935B1 (ko) * 2006-11-27 2008-01-31 주식회사 코우 랙바아의 랙성형방법
JP2014124767A (ja) * 2012-12-27 2014-07-07 Neturen Co Ltd ラック製造装置及びラック製造方法
JP2014214810A (ja) * 2013-04-25 2014-11-17 高周波熱錬株式会社 ダブルピニオン式ラックバー

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JP2018179271A (ja) 2018-11-15

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