WO2023132190A1 - ボールねじ装置およびねじ軸の製造方法 - Google Patents

ボールねじ装置およびねじ軸の製造方法 Download PDF

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Publication number
WO2023132190A1
WO2023132190A1 PCT/JP2022/045691 JP2022045691W WO2023132190A1 WO 2023132190 A1 WO2023132190 A1 WO 2023132190A1 JP 2022045691 W JP2022045691 W JP 2022045691W WO 2023132190 A1 WO2023132190 A1 WO 2023132190A1
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WO
WIPO (PCT)
Prior art keywords
carrier
shaft
ball screw
axial direction
peripheral surface
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.)
Ceased
Application number
PCT/JP2022/045691
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
諒 瀬川
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.)
NSK Ltd
Original Assignee
NSK Ltd
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 NSK Ltd filed Critical NSK Ltd
Priority to CN202280015119.9A priority Critical patent/CN116917644A/zh
Priority to JP2023522792A priority patent/JP7338810B1/ja
Priority to US18/290,108 priority patent/US12222023B2/en
Priority to EP22918776.0A priority patent/EP4279766B1/en
Publication of WO2023132190A1 publication Critical patent/WO2023132190A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
    • B60T13/745—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive acting on a hydraulic system, e.g. a master cylinder
    • 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
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
    • F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
    • F16H25/2214—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls with elements for guiding the circulating balls
    • 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
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/581—Raceways; Race rings integral with other parts, e.g. with housings or machine elements such as shafts or gear wheels
    • 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
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/64—Special methods of manufacture
    • 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
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
    • F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
    • 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
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2361/00—Apparatus or articles in engineering in general
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/18—Mechanical mechanisms
    • F16D2125/20—Mechanical mechanisms converting rotation to linear movement or vice versa
    • F16D2125/34—Mechanical mechanisms converting rotation to linear movement or vice versa acting in the direction of the axis of rotation
    • F16D2125/36—Helical cams, Ball-rotating ramps
    • 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
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/204—Axial sliding means, i.e. for rotary support and axial guiding of nut or screw shaft
    • 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
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/2062—Arrangements for driving the actuator
    • F16H2025/2075—Coaxial drive motors
    • 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
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/2062—Arrangements for driving the actuator
    • F16H2025/2087—Arrangements for driving the actuator using planetary gears
    • 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
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
    • F16H2025/2481—Special features for facilitating the manufacturing of spindles, nuts, or sleeves of screw devices

Definitions

  • the present disclosure relates to a ball screw device and a method of manufacturing a screw shaft that constitutes the ball screw device.
  • a ball screw device allows balls to roll between the screw shaft and the nut, so it is more efficient than a sliding screw device that directly contacts the screw shaft and the nut. For this reason, ball screw devices are used in various mechanical devices such as electric brake devices and automatic manual transmissions (AMT) of automobiles, positioning devices of machine tools, etc., in order to convert rotary motion of a drive source such as an electric motor into linear motion. built in.
  • AMT automatic manual transmissions
  • a ball screw device includes a screw shaft having a spiral shaft-side ball screw groove on its outer peripheral surface, a nut having a spiral nut-side ball screw groove on its inner peripheral surface, and a shaft-side ball screw groove and a nut-side ball screw groove. and a plurality of balls disposed between.
  • a ball screw device one of the screw shaft and the nut is used as a rotary motion element, and the other of the screw shaft and the nut is used as a linear motion element, depending on the application.
  • FIG. 11 shows a conventional ball screw device 100 described in Japanese Patent Laid-Open No. 2009-286137.
  • the ball screw device 100 includes a screw shaft 101, a nut 102, and a plurality of balls (not shown).
  • the threaded shaft 101 has a threaded portion 103 and a fitting shaft portion 104 arranged adjacent to one side of the threaded portion 103 in the axial direction.
  • a spiral shaft-side ball screw groove 105 is formed on the outer peripheral surface of the threaded portion 103 .
  • the fitting shaft portion 104 has an outer diameter smaller than that of the threaded portion 103 .
  • the threaded shaft 101 is arranged coaxially with the nut 102 with the threaded portion 103 inserted inside the nut 102 .
  • the nut 102 has a cylindrical shape.
  • a spiral nut-side ball screw groove (not shown) is formed on the inner peripheral surface of the nut 102 .
  • Nut 102 engages a plurality of guide rods 107 supported against housing 106 . This prevents the nut 102 from rotating.
  • the shaft-side ball screw groove 105 and the nut-side ball screw groove are arranged so as to face each other in the radial direction, forming a spiral load path.
  • a start point and an end point of the load path are connected by circulation means (not shown). Therefore, the ball that has reached the end point of the load path is returned to the start point of the load path through the circulation means.
  • the start point and end point of the load path are interchanged according to the relative displacement direction of the screw shaft 101 and the nut 102 in the axial direction, that is, the relative rotation direction of the screw shaft 101 and the nut 102 .
  • the rotation of the electric motor 108 which is the drive source, is reduced by the pulley device 109 and transmitted to the screw shaft 101.
  • the driven pulley 110 is fitted to the fitting shaft portion 104 provided at one end portion of the screw shaft 101 in the axial direction so that the driven pulley 110 cannot rotate relative to the fitting shaft portion 104 .
  • a drive pulley 112 is fitted to the tip of the motor shaft 111 of the electric motor 108 so as not to be relatively rotatable.
  • a belt 113 is stretched between the drive pulley 112 and the driven pulley 110 .
  • a pulley device is used as in the conventional structure described in Japanese Patent Laid-Open No. 2009-286137, or a spur gear type reduction mechanism is used. is considered to be used.
  • the present inventors used a planetary speed reduction mechanism, which has advantages such as coaxial arrangement of the input shaft and output shaft and reduction in size of the device, compared to a pulley device or a spur gear type speed reduction mechanism. , to transmit the rotation of the electric motor to the screw shaft that constitutes the ball screw device.
  • FIG. 12 shows an undisclosed ball screw device that the inventors conceived prior to completing the ball screw device of the present disclosure.
  • a carrier 115 constituting a planetary speed reduction mechanism 114 is fitted to one end in the axial direction of a screw shaft 101a constituting a ball screw device 100a so as not to rotate relative to it.
  • a fitting shaft portion 104a formed at one end in the axial direction of the screw shaft 101a is spline-fitted into a mounting hole 116 formed in the center portion of the carrier 115 in the radial direction.
  • a plurality of planetary gears 117 are rotatably supported with respect to the carrier 115 .
  • a pinion pin 119 is inserted and supported through a plurality of support holes 118 formed in a radially intermediate portion of the carrier 115
  • a planetary gear 117 is rotatably supported around the pinion pin 119 .
  • a plurality of planetary gears 117 are arranged between a sun gear 120 fixed to the tip of the motor shaft 111a of the electric motor 108a and a ring gear 121 arranged coaxially with the sun gear 120 and fixed to a housing 124. are placed.
  • a plurality of planetary gears 117 mesh with the sun gear 120 and the ring gear 121 respectively.
  • the carrier 115 fixed to the fitting shaft portion 104a of the screw shaft 101a is rotatably supported with respect to the housing 124 using the rolling bearing 122. Therefore, the axial force transmitted to carrier 115 is supported by housing 124 via rolling bearing 122 .
  • an outward flange-shaped collar portion 123 is provided on a part of the outer peripheral surface of the carrier 115 to The portion 123 is brought into contact with the rolling bearing 122 .
  • the carrier 115 is rotatably supported with respect to the housing 124 by using the rolling bearing 122 which is separate from the carrier 115. Therefore, the number of parts is increased and the ball screw device 100a is Assemblability tends to deteriorate.
  • An object of the present disclosure is to provide a ball screw device that can reduce the number of parts and improve the ease of assembly even when adopting a structure that rotationally drives a screw shaft using a planetary speed reduction mechanism. aim.
  • a ball screw device includes a screw shaft, a nut, a plurality of balls, and a rolling bearing.
  • the screw shaft constitutes a threaded portion having a helical shaft-side ball thread groove on an outer peripheral surface thereof, and a planetary reduction mechanism integrally formed with the threaded portion and disposed on one axial side of the threaded portion. and a carrier that rotates during use.
  • the nut has a helical nut-side ball screw groove on its inner peripheral surface and moves linearly during use.
  • the plurality of balls are arranged between the shaft-side ball screw groove and the nut-side ball screw groove.
  • the rolling bearing includes an outer ring having an outer ring raceway on its inner peripheral surface, an inner ring raceway provided in a portion facing the outer ring raceway in a radial direction, and a rollable arrangement between the outer ring raceway and the inner ring raceway. and a plurality of rolling elements arranged to rotatably support the carrier.
  • the inner ring raceway is directly formed on the outer peripheral surface of the carrier. That is, an inner ring, which constitutes the rolling bearing and has the inner ring raceway, is configured integrally with the carrier.
  • the threaded portion may have an incompletely threaded portion at one end in the axial direction of the outer peripheral surface.
  • the distance from the one end in the axial direction of the nut-side ball screw groove to the side surface of the nut on the one axial direction is set to the distance from the boundary between the incomplete thread portion and the shaft-side ball screw groove to the carrier. can be larger than the distance to the side surface on the other side in the axial direction.
  • the screw portion has a tapered shape in which the generatrix shape is inclined in a direction in which the outer diameter decreases toward the one axial direction side at the end portion on the one axial direction side of the outer peripheral surface. of recesses.
  • the side surface of the outer ring on one side in the axial direction can be offset to the other side in the axial direction from the side surface of the carrier on one side in the axial direction. That is, the side surface on the one axial side of the outer ring can be arranged in parallel with the side surface on the one axial side of the carrier and positioned on the other side in the axial direction from the side surface on the one axial side of the carrier. can.
  • the axial width dimension of the carrier can be made larger than the axial width dimension of the outer ring.
  • the carrier may have support holes for inserting and supporting pinion pins constituting the planetary speed reduction mechanism at a plurality of locations in the circumferential direction of the radial intermediate portion. .
  • the support hole can be configured by a through hole axially penetrating the carrier.
  • the support hole may be a bottomed hole that is open only on one side surface of the carrier in the axial direction.
  • the carrier has a protruding portion that protrudes toward the one axial side on a portion of the side surface on the one axial side that includes the opening of the support hole. be able to.
  • the projecting portion may have an annular shape.
  • the projecting portion can be provided only around the opening of the support hole.
  • a method for manufacturing a screw shaft according to an aspect of the present disclosure is a screw shaft that rotates during use, and includes: a threaded portion; a carrier that constitutes a planetary speed reduction mechanism, the threaded portion has a helical shaft-side ball screw groove on its outer peripheral surface, and the carrier has an inner ring raceway that constitutes a rolling bearing on its outer peripheral surface.
  • a method for manufacturing a threaded shaft comprising a forging process and a rolling process.
  • the material is forged to form an intermediate material integrally comprising a disk portion and a shaft-like portion and having a T-shaped cross-sectional shape in the axial direction.
  • the intermediate material is subjected to an in-feed rolling process to form the shaft-side ball screw groove on the outer peripheral surface of the shaft-shaped portion.
  • a method for manufacturing a screw shaft according to an aspect of the present disclosure can include a raceway groove cutting step of cutting the outer peripheral surface of the disk portion to form the inner ring raceway.
  • a carrier-side center hole is formed in one side surface of the disk portion in the axial direction, and A screw-side center hole can be formed coaxially with the carrier-side center hole on the other side surface of the shaft-shaped portion in the axial direction.
  • the intermediate material is centered using the carrier-side center hole and the screw-side center hole. In this state, the rolling process and the cutting process can be performed.
  • a heat-hardened layer is formed in a range including the outer peripheral surface of the disc portion and the outer peripheral surface of the shaft-like portion, and then the carrier side Pinion pins constituting the planetary speed reduction mechanism are provided at a plurality of locations in the circumferential direction of the radially intermediate portion of the disk portion in a state in which the intermediate material is centered using the center hole and the screw-side center hole. It is possible to form a support hole for inserting and supporting the .
  • the shaft of the shaft-shaped portion is attached to the end portion on one side in the axial direction of the shaft-shaped portion. It is possible to form a small diameter portion having an outer diameter smaller than the outer diameter of the portion deviating from the end on the one direction side.
  • the screw shaft is rotated via a planetary reduction mechanism.
  • a driving structure is adopted, the number of parts is suppressed and the assembling efficiency is improved.
  • FIG. 1 is a cross-sectional view showing an example of a structure in which a ball screw device and a planetary speed reduction mechanism of a first example of an embodiment of the present disclosure are combined.
  • FIG. 2 is a cross-sectional view showing the ball screw device of the first example.
  • FIG. 3 is a cross-sectional view of the ball screw device of the first example, showing a state in which the nut is relatively moved to one side in the axial direction with respect to the screw shaft.
  • 4(A) to 4(E) show the manufacturing method of the screw shaft of the first example in order of steps.
  • FIG. 5 is a partially enlarged cross-sectional view of the ball screw device of the second example of the embodiment of the present disclosure.
  • FIG. 6 is a partially enlarged view of the screw shaft that constitutes the ball screw device of the second example.
  • FIG. 7 is a diagram corresponding to FIG. 2 showing a ball screw device of a third example of the embodiment of the present disclosure.
  • FIG. 8 is a diagram corresponding to FIG. 2 showing a ball screw device of a fourth example of the embodiment of the present disclosure.
  • FIG. 9 is a cross-sectional view showing an example of a structure in which a ball screw device and a planetary speed reduction mechanism are combined according to the fifth example of the embodiment of the present disclosure.
  • FIG. 10 is a diagram corresponding to FIG. 2 showing a ball screw device of a sixth example of the embodiment of the present disclosure.
  • FIG. 10 is a diagram corresponding to FIG. 2 showing a ball screw device of a sixth example of the embodiment of the present disclosure.
  • FIG. 11 is a sectional view showing a conventional ball screw device in which a ball screw device and a pulley device are combined.
  • FIG. 12 is a sectional view showing a ball screw device having an undisclosed structure in which a ball screw device and a planetary speed reduction mechanism are combined.
  • FIG. 1 to 4 show an example of a ball screw device 1 according to a first embodiment of the present disclosure and an example of a structure in which the ball screw device 1 and a planetary speed reduction mechanism 8 are combined.
  • the ball screw device 1 of this example is incorporated in, for example, an electric brake booster device and used for applications such as converting rotary motion of an electric motor, which is a drive source, into linear motion to operate a piston of a hydraulic cylinder.
  • the ball screw device 1 includes a screw shaft 2, a nut 3, a plurality of balls 4, and rolling bearings 5.
  • the screw shaft 2 is a rotary motion element that is driven to rotate via a planetary speed reduction mechanism 7 by an electric motor 6 that is a drive source, and rotates during use.
  • the screw shaft 2 is inserted through the inside of the nut 3 and arranged coaxially with the nut 3 .
  • the nut 3 is a linear motion element that is prevented from co-rotating with respect to the screw shaft 2 by a non-illustrated anti-rotation mechanism and moves linearly during use. That is, the ball screw device 1 of this example is used in a mode in which the screw shaft 2 is rotationally driven and the nut 3 is linearly moved.
  • a spiral load path 8 is provided between the outer peripheral surface of the screw shaft 2 and the inner peripheral surface of the nut 3 .
  • a plurality of balls 4 are rotatably arranged in the load path 8 .
  • the balls 4 that have reached the end point of the load path 8 are returned to the starting point of the load path 8 through the circulation groove 9 formed on the inner peripheral surface of the nut 3 .
  • the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction with respect to the screw shaft 2 unless otherwise specified.
  • the one axial side refers to the right side in FIGS. 1 to 3
  • the other axial side refers to the left side in FIGS.
  • the threaded shaft 2 is made of metal and has a threaded portion 10 and a carrier 11 that constitutes the planetary speed reduction mechanism 7 and is arranged adjacent to one side of the threaded portion 10 in the axial direction.
  • the threaded portion 10 and the carrier 11 are coaxially arranged and integrally formed with each other.
  • the carrier 11 has a substantially disk shape and has a larger outer diameter than the threaded portion 10 having a substantially cylindrical shape. Therefore, the screw shaft 2 has a substantially T-shaped cross-sectional shape in the axial direction.
  • the screw portion 10 has a spiral shaft-side ball screw groove 12 on its outer peripheral surface.
  • the shaft-side ball screw groove 12 is formed by infeed rolling.
  • the number of threads of the shaft-side ball screw groove 12 is one.
  • a cross-sectional groove shape (groove bottom shape) of the shaft-side ball screw groove 12 has a Gothic arch shape or a circular arc shape.
  • the threaded portion 10 has a bottomed threaded side center hole 13 in the radial center portion of the end surface on the other side in the axial direction.
  • the threaded portion 10 has an incompletely threaded portion 38 in which the shaft-side ball screw groove 12 with a perfect groove bottom shape is not formed at one end in the axial direction of the outer peripheral surface.
  • the incomplete threaded portion 38 has a shallower groove depth than the shaft-side ball screw groove 12 .
  • the groove depth of the incomplete threaded portion 38 is gradually shallower toward one side in the axial direction.
  • the space around the incomplete threaded portion 38 can be used as a storage space for peripheral components.
  • the carrier 11 has an inner ring raceway 14 that constitutes the rolling bearing 5 .
  • the inner ring raceway 14 is directly formed in the axially intermediate portion (central portion in this example) of the outer peripheral surface of the carrier 11 . Therefore, the carrier 11 functions not only as a component of the planetary speed reduction mechanism 7 but also as an inner ring forming the rolling bearing 5 .
  • the carrier and the inner ring forming the rolling bearing are integrally formed.
  • the rolling bearing 5 is composed of a four-point contact ball bearing capable of supporting a radial load and an axial load in both directions.
  • the portions outside the inner ring raceway 14 on both sides in the axial direction are formed into a partially cylindrical surface.
  • seal concave grooves over the entire circumference on both sides in the axial direction of the outer peripheral surface of the carrier so that the inner diameter side end of the seal ring, which is an optional element for sealing the rolling bearing, is brought into sliding contact. can.
  • the carrier 11 has support holes 15 for inserting and supporting the pinion pins 33 constituting the planetary speed reduction mechanism 7 at a plurality of locations (three locations in this example) in the circumferential direction of the radially intermediate portion.
  • the plurality of support holes 15 are arranged at regular intervals in the circumferential direction. Also, the central axes of the plurality of support holes 15 are arranged parallel to each other.
  • Each support hole 15 is formed by a through hole penetrating through the carrier 11 in the axial direction. That is, the support hole 15 is open not only on one side surface of the carrier 11 in the axial direction, but also on the other side surface of the carrier 11 in the axial direction.
  • the support hole can also be configured by a bottomed hole that is open only on one side surface of the carrier in the axial direction.
  • the inner diameter of the support hole 15 is constant over the axial direction.
  • the diameter of an imaginary circle passing through the radially inner end of each of the plurality of support holes 15 (inscribed circle diameter) is approximately the same as the outer diameter of the threaded portion 10 .
  • the diameter of the virtual circle passing through the radially outer end of each of the plurality of support holes 15 (circumscribed circle diameter) is slightly smaller than the outer diameter of the nut 3 .
  • the carrier 11 is directed toward the one axial side of the radially intermediate portion including the openings of the plurality of support holes 15 relative to the radially outer and radially inner portions. It has an overhanging portion 16 that overhangs.
  • the projecting portion 16 has an annular shape that is continuous in the circumferential direction.
  • the inner diameter of the projecting portion 16 is smaller than the diameter of the imaginary cylindrical surface passing through the groove bottom of the shaft-side ball screw groove 12 .
  • the outer diameter of the projecting portion 16 is larger than the outer diameter of the nut 3 and smaller than the outer diameter of the groove bottom portion of the inner ring raceway 14 .
  • a side surface (tip surface) on one side in the axial direction of the projecting portion 16 is a flat surface that exists on a virtual plane perpendicular to the central axis of the carrier 11 .
  • the projecting portion 16 and the portion of the side surface on one axial side of the carrier 11 that is radially outward of the projecting portion 16 are inclined in a direction in which the outer diameter increases toward the other axial direction. They are connected by an outer diameter side connection surface 17 .
  • the overhanging portion 16 and the portion of the side surface on one axial side of the carrier 11 that is located radially inward of the overhanging portion 16 are inclined in a direction in which the inner diameter decreases toward the other axial side. , are connected by a connecting surface 18 on the inner diameter side.
  • the side surface of the carrier 11 on the other side in the axial direction is a flat surface that exists on a virtual plane perpendicular to the central axis of the carrier 11 .
  • the carrier 11 has a bottomed carrier-side center hole 19 in the radial center of one side surface in the axial direction.
  • the carrier-side center hole 19 and the thread-side center hole 13 provided in the threaded portion 10 are arranged coaxially with each other.
  • the carrier 11 is subjected to induction hardening treatment and tempering treatment on the outer peripheral surface on which the inner ring raceway 14 is formed, and a heat-treated hardened layer is formed.
  • the heat-hardened layer is not formed on the side surface of the carrier 11 on one side in the axial direction and the side surface on the other side in the axial direction.
  • the screw shaft 2 is arranged coaxially with the nut 3 with the threaded portion 10 inserted inside the nut 3 .
  • the screw shaft 2 is composed of the threaded portion 10 and the carrier 11, but the screw shaft can also be provided with a fitting shaft portion for externally fitting and fixing other members.
  • the nut 3 is made of metal and has a cylindrical shape as a whole.
  • the nut 3 has a helical nut-side ball screw groove 20 and a circulation groove 9 on its inner peripheral surface.
  • the nut-side ball screw groove 20 has a helical shape and is formed by subjecting the inner peripheral surface of the nut 3 to grinding, cutting, rolling tapping, or cutting tapping, for example.
  • the nut-side ball screw groove 20 has the same lead as the shaft-side ball screw groove 12 . Therefore, in a state in which the threaded portion 10 of the screw shaft 2 is inserted through the nut 3, the shaft-side ball screw groove 12 and the nut-side ball screw groove 20 are arranged so as to face each other in the radial direction, forming a spiral shape.
  • a load path 8 is configured.
  • the number of threads of the nut-side ball screw groove 20 is one, like the shaft-side ball screw groove 12 .
  • the cross-sectional groove shape of the nut-side ball screw groove 20 is also a Gothic arch shape or a circular arc shape, like the shaft-side ball screw groove 12 .
  • the circulation groove 9 has a substantially S-shape and is formed on the inner peripheral surface of the nut 3 by forging such as cold forging.
  • the circulation groove 9 smoothly connects axially adjacent portions of the nut-side ball screw groove 20 and connects the start point and the end point of the load path 8 . Therefore, the ball 4 that has reached the end point of the load path 8 is returned to the start point of the load path 8 through the circulation groove 9 .
  • the start point and the end point of the load path 8 are interchanged according to the direction of relative displacement between the screw shaft 2 and the nut 3 in the axial direction (relative rotation direction between the screw shaft 2 and the nut 3).
  • the circulation groove 9 has a substantially semicircular cross-sectional shape.
  • the circulation groove 9 has a groove width slightly larger than the diameter of the balls 4, and has a groove depth that allows the balls 4 moving in the circulation groove 9 to climb over the threads of the shaft-side ball screw groove 12. ing.
  • the nut 3 has a cylindrical surface portion 43 in which the nut-side ball screw groove 20 is not formed at one end in the axial direction of the inner peripheral surface. Therefore, in this example, as shown in FIG. can be placed in This prevents the balls 4 from being caught between the incomplete threaded portion 38 and the nut-side ball thread groove 20, thereby preventing the driving torque of the screw shaft 2 from increasing.
  • the distance La from the end of the nut-side ball screw groove 20 on one axial side to the side surface of the nut 3 on one axial side is defined by the incomplete thread portion 38 and the shaft-side ball. It is made larger than the distance Lb from the boundary with the thread groove 12 to the side surface of the carrier 11 on the other side in the axial direction (La>Lb).
  • the nut 3 has an outward flange-like flange 21 at one end in the axial direction of the outer peripheral surface located radially outward of the cylindrical surface portion 43 .
  • the flange 21 is engaged with anti-rotation members (not shown) provided on a fixed member such as the housing 23 at a plurality of locations (three locations in this example) in the circumferential direction to prevent the nut 3 from co-rotating. of engagement grooves 22 are provided.
  • a protrusion (key) provided on the inner peripheral surface of a fixed member such as a housing is engaged with a concave groove axially formed on the outer peripheral surface of the nut.
  • a small-diameter portion having a smaller outer diameter than the portion adjacent to the one axial side can be formed at the end portion on the other axial side of the outer peripheral surface of the nut 3 .
  • a fitting cylinder such as a piston (not shown) can be externally fitted and fixed to the small diameter portion.
  • Balls 4 are steel balls having a predetermined diameter, and are arranged in load path 8 and circulation groove 9 so as to be able to roll.
  • the balls 4 arranged in the load path 8 roll while being subjected to a compressive load, whereas the balls 4 arranged in the circulation groove 9 are pushed by the succeeding balls 4 and roll without being subjected to a compressive load. move.
  • the rolling bearing 5 rotatably supports the carrier 11 constituting the screw shaft 2 with respect to the housing 23 and supports the axial force transmitted to the carrier 11 by the housing 23 .
  • the rolling bearing 5 is composed of a four-point contact ball bearing capable of supporting a radial load and an axial load in both directions.
  • rolling bearings other than four-point contact ball bearings such as three-point contact ball bearings, multi-point contact ball bearings, single-row deep groove ball bearings, double-row deep groove ball bearings, double-row angular contact ball bearings, tapered rolling Any bearing, whether single or double row, capable of supporting radial and axial loads can be used, such as row tapered roller bearings.
  • the rolling bearing 5 includes an outer ring 25, an inner ring raceway 14, a plurality of rolling elements 26, and a retainer 27.
  • the outer ring 25 has an annular shape, and has an outer ring raceway 28 in the axially central portion of the inner peripheral surface.
  • the outer ring 25 is internally fitted and fixed to the housing 23 and does not rotate during use.
  • the one side surface of the outer ring 25 in the axial direction becomes the one side surface of the carrier 11 in the axial direction (the side surface of the protruding portion 16). (side surface on one side in the axial direction) is offset to the other side in the axial direction.
  • the axial width dimension of the outer ring 25 is made smaller than the axial width dimension of the carrier 11 .
  • the outer ring raceway 36 is composed of a compound curved surface having a Gothic arch shape in cross section. It is also possible to provide a retaining ring that is engaged with a portion of the inner peripheral surface of the housing 23 that is axially deviated from the portion where the outer ring 25 is internally fitted, so that the outer ring 25 is prevented from coming off by the retaining ring. can.
  • the side surface on one axial side of the outer ring 25 can be arranged on the same plane as the side surface on the one axial side of the carrier 11 , or can be arranged on the one axial side of the side surface on the one axial direction side of the carrier 11 . It can also be offset.
  • the portions outside the outer ring raceway 28 in the axial direction are configured in a partially cylindrical surface shape.
  • locking grooves may be formed along the entire circumference on both sides in the axial direction of the inner peripheral surface of the outer ring.
  • the inner ring raceway 14 that constitutes the rolling bearing 5 is formed directly in the axially intermediate portion of the outer peripheral surface of the carrier 11 that faces the outer ring raceway 28 in the radial direction, and the inner ring is omitted.
  • the plurality of rolling elements 26 are made of steel or ceramics, and are arranged between the outer ring raceway 28 and the inner ring raceway 14 at regular intervals in the circumferential direction. Balls are used as the rolling elements 26 in this example.
  • the retainer 27 has an annular shape and has pockets 29 at regular intervals in the circumferential direction.
  • a rolling element 26 is rotatably held inside the pocket 29 .
  • a planetary speed reduction mechanism 7 is used to transmit the rotation of the electric motor 6 to the screw shaft 2 that constitutes the ball screw device 1 .
  • the planetary speed reduction mechanism 7 includes a sun gear 30 , a plurality of planetary gears 31 , a ring gear 32 , a carrier 11 and pinion pins 33 .
  • the sun gear 30 is fixed to the tip of the motor shaft (sun gear shaft) 34 of the electric motor 6 .
  • the ring gear 32 is arranged coaxially with the sun gear 30 and is internally fitted and fixed to the housing 23 .
  • the housing 23 may be divided into two parts, and the part into which the ring gear 32 is fitted and the part into which the outer ring 25 constituting the rolling bearing 5 is fitted may be composed of separate members.
  • a plurality of (three in this example) planetary gears 31 are arranged at regular intervals in the circumferential direction and are rotatably supported on the carrier 11 .
  • the other half of the pinion pin 33 in the axial direction is press-fitted into the support hole 15 formed in the carrier 11 , and the half of the pinion pin 33 on the one side in the axial direction is pushed out from the support hole 15 in the axial direction. It protrudes to one side.
  • the planetary gear 31 is rotatably supported via a slide bearing or needle bearing (C&R) (not shown).
  • the method of fixing the pinion pin to the support hole is not particularly limited, and a fixing structure using caulking or locking pins can also be adopted.
  • a fixing structure using caulking or locking pins can also be adopted.
  • a structure in which the pinion pin is supported on both sides can be adopted.
  • the number of planetary gears is not limited to three, and may be two or four or more.
  • the planetary gear 31 meshes with the sun gear 30 and the ring gear 32 respectively.
  • the nut 3 is linearly moved by rotating the screw shaft 2 through the planetary speed reduction mechanism 7 by the electric motor 6 which is the drive source. Specifically, when the electric motor 6 is energized and the sun gear 30 is rotated in a predetermined direction, the planetary gear 31 revolves around the sun gear 30 while rotating. The orbital motion of the planetary gear 31 is transmitted to the screw shaft 2 via the carrier 11 and rotates the screw shaft 2 in a predetermined direction, thereby linearly moving the nut 3 .
  • the nut 3 moves relatively to the one side in the axial direction with respect to the screw shaft 2, turning the sun gear 30 toward the other side in the circumferential direction. , the nut 3 moves relative to the screw shaft 2 in the other axial direction.
  • the screw shaft 2 can be rotationally driven via the planetary speed reduction mechanism 7 by the electric motor 6 as the drive source. Stroke ends associated with the relative movement of the nut 3 to the one axial side and the other axial side with respect to the screw shaft 2 can be regulated using various conventionally known stroke limiting mechanisms.
  • the screw shaft 2 that constitutes the ball screw device 1 of this example can be manufactured, for example, by a manufacturing method including the following steps.
  • a first cutting/grinding process, a raceway groove cutting process, a heat treatment process, and a second cutting/grinding process are provided as optional and additional processes.
  • the forging step is a step of forging a material to form an intermediate material integrally comprising a disc portion and a shaft-like portion and having a T-shaped cross-sectional shape in the axial direction.
  • a metal material (billet) (not shown) is subjected to hot forging to form an intermediate material 35 as shown in FIG. 4(A).
  • the intermediate material 35 is integrally provided with a columnar shaft portion 36 that is processed into the threaded portion 10 and a disk portion 37 that is processed into the carrier 11, and has a T-shaped cross section in the axial direction. have a shape.
  • a groove having a shape similar to the inner ring raceway 14 may be roughly formed on the outer peripheral surface of the disc portion 37 .
  • the carrier-side center hole 19 is formed in the side surface of the disk portion 37 on one side in the axial direction, and the side surface of the shaft-like portion 36 on the other side in the axial direction is formed.
  • a step of forming the screw-side center hole 13 coaxially with the carrier-side center hole 19 is provided.
  • the intermediate material 35 is cut. Specifically, the outer peripheral surface of the shaft-shaped portion 36 and the end surface on the other side in the axial direction, and the side surface on the one side in the axial direction of the disc portion 37 are subjected to cutting.
  • the axial one end of the shaft-shaped portion 36 has a diameter larger than the outer diameter of the portion of the shaft-shaped portion 36 deviating from the axial one-side end.
  • a small-diameter portion 44 having a small outer diameter is formed, and a screw-side center hole 13 is formed in the end surface of the shaft-like portion 36 on the other side in the axial direction.
  • the outer peripheral surface of the small diameter portion 44 becomes the incomplete thread portion 38 in the completed state of the screw shaft 2 .
  • the protruding portion 16 and the carrier-side center hole 19 are formed on one side surface of the disk portion 37 in the axial direction.
  • the screw-side center hole 13 and the carrier-side center hole 19 are formed coaxially with each other.
  • the small-diameter portion 44 can also be formed at the end portion on one side in the axial direction of the outer peripheral surface of the shaft-shaped portion 36 in the forging process.
  • the rolling process is a process of forming the shaft-side ball screw groove 12 on the outer peripheral surface of the shaft-shaped portion 36 by subjecting the intermediate material 35 to an in-feed rolling process.
  • the intermediate material 35 is subjected to an in-feed rolling process, and as shown in FIG. A spiral shaft-side ball screw groove 12 is formed. Since the cross-sectional shape of the intermediate material 35 in the axial direction is T-shaped, it is difficult to subject the intermediate material 35 to through-feed rolling.
  • the shaft-side ball screw groove 12 is formed on the outer peripheral surface of the shaft-like portion 36 by bringing a pair of rotating rolling dies close to the shaft-like portion 36 by infeed rolling. Form.
  • such an infeed type rolling process is performed with the intermediate material 35 centered using the screw-side center hole 13 and the carrier-side center hole 19 .
  • an incomplete threaded portion 38 is formed on the outer peripheral surface of the small diameter portion 44 of the shaft-like portion 36 .
  • infeed rolling is performed to form the shaft-side ball screw groove 12 .
  • the reserve meat can escape to the small diameter portion 44 side. Therefore, the shape and dimensions of the shaft-side ball screw groove 12 can be stabilized.
  • the raceway groove cutting process is provided after the rolling process.
  • the raceway groove cutting step is a step of cutting the outer peripheral surface of the disk portion 37 to form the inner ring raceway 14 .
  • the inner ring raceway 14 is formed in the axially intermediate portion of the outer peripheral surface of the disc portion 37 by cutting the outer peripheral surface of the disc portion 37 as shown in FIG. 4(D). Further, cutting for forming the inner ring raceway 14 is performed in a state where the intermediate material 35 is centered using the screw-side center hole 13 and the carrier-side center hole 19 .
  • the inner ring raceway 14 is formed by adjusting the shape of the grooves in the raceway groove cutting process. Note that the rolling process may be performed after the raceway groove cutting process.
  • the heat treatment process is provided after the rolling process and the raceway groove cutting process.
  • the heat treatment step is a step of forming a heat-treated hardened layer in a range including the outer peripheral surface of the disk portion 37 and the outer peripheral surface of the shaft-like portion 36 .
  • a heat-hardened layer is formed on the portion where the inner ring raceway 14 is formed.
  • the outer peripheral surface of the shaft-shaped portion 36 and the outer peripheral surface of the disk portion 37 are subjected to induction hardening treatment and tempering treatment, and the axial side surface of the disk portion 37 (the side surface on one side in the axial direction and the shaft The side surface on the other side) is not subjected to induction hardening treatment and tempering treatment.
  • the quenching treatment sub-quenching, carburizing quenching, or the like can be employed in addition to induction quenching.
  • the axial side surface of the disk portion 37 is not subjected to the induction hardening treatment and the tempering treatment in the heat treatment step of the preceding process, the axial side surface of the disk portion 37 is not deformed by heat treatment. do not have. For this reason, it is possible to drill the intermediate portion in the radial direction of the disc portion 37 without performing a removing process for removing the heat-treated deformed portion. Further, since the radial intermediate portion of the disk portion 37 has the same hardness as the raw material, it can be easily drilled.
  • the inner ring raceway 14 formed on the outer peripheral surface of the disk portion 37 is ground.
  • the cutting (drilling) for forming the support hole 15 and the grinding of the inner ring raceway 14 are performed using the screw-side center hole 13 and the carrier-side center hole 19, respectively. is centered.
  • the intermediate material 35 is submerged quenched or carburized, the hardness of the axial side surface of the disc portion 37 increases, but The part can be drilled.
  • the screw shaft 2 is obtained from the intermediate material 35 by forming the threaded portion 10 from the shaft-like portion 36 and forming the carrier 11 from the disk portion 37 through the manufacturing process described above. .
  • the ball screw device 1 of this example employs a structure in which the screw shaft 2 is rotationally driven using the planetary speed reduction mechanism 7, the number of parts is reduced and the assembly efficiency is improved. is planned.
  • the inner ring raceway 14 forming the rolling bearing 5 is directly formed on the outer peripheral surface of the carrier 11, the inner ring forming the rolling bearing 5 can be omitted. Therefore, compared to the structure shown in FIG. 12, in which an inner ring separate from the carrier is externally fitted and fixed to the carrier, the number of parts is reduced, the number of assembly steps is reduced, and , and improved assembly. Further, in this example, there is no need to form a flange for transmitting force in the axial direction on the outer peripheral surface of the carrier 11, and the number of processing steps can be reduced accordingly.
  • the carrier 11 since the carrier 11 does not need a flange, it is sufficient to form the heat-hardened layer only on the outer peripheral surface including the inner ring raceway 14 . Therefore, when the axial side surface of the carrier 11 is drilled to form the support holes 15, there is no need to remove the heat-hardened layer, which reduces the number of processing steps. can.
  • the screw portion 10 and the carrier 11 are also integrally formed, the number of parts is reduced compared to the case where the carrier is fixed to the screw shaft separately from the screw shaft. can be reduced, and the number of assembly man-hours can be reduced. Further, since the degree of coaxiality between the screw portion 10 and the carrier 11 can be increased, quietness during operation of the ball screw device 1 can be improved.
  • the side surface of the outer ring 25 on one side in the axial direction is offset from the side surface on the one side in the axial direction of the carrier 11 to the other side in the axial direction. can be prevented from interfering with the end face on the other side in the axial direction.
  • an overhanging portion 16 having a flat surface on the one axial side is formed in a radially intermediate portion including the opening of the support hole 15 . Therefore, it is possible to prevent the planetary gear 31 from moving to the other side in the axial direction by using the side surface on the one side in the axial direction of the projecting portion 16 .
  • the side surface of the planetary gear 31 on the other side in the axial direction and the side surface on the one side in the axial direction of the projecting portion 16 are in direct contact with each other.
  • Another member such as a slide washer may be interposed between the protruded portion 16 and the side surface on one side in the axial direction.
  • the same (common) reference such as the screw-side center hole 13 and the carrier-side center hole 19 is used to 15 processes can be performed. Therefore, the dimensional accuracy of the screw shaft 2 can be improved. Therefore, the mechanical efficiency of the ball screw device 1 can be improved, and the meshing accuracy between the planetary gear 31 and the sun gear 30 and the meshing accuracy between the planetary gear 31 and the ring gear 32 can be improved.
  • the carrier 11 since the carrier 11 is rotatably supported by the housing 23 using the rolling bearing 5 , the axial force transmitted to the carrier 11 is transferred to the housing 23 via the rolling bearing 5 .
  • a nut-side ball screw groove 20 is formed on the nut 3a used in this example, extending to the end on one side in the axial direction of the inner peripheral surface. That is, the nut 3a does not have the cylindrical surface portion 43 that the nut 3 had in the first example.
  • the threaded shaft 2d has a tapered concave portion formed at the end portion of the outer peripheral surface of the threaded portion 10 on one side in the axial direction. (Recessed portion) 45 is provided. That is, the threaded shaft 2d has the recessed portion 45 by removing the incompletely threaded portion 38 included in the threaded shaft 2 in the first example by cutting.
  • FIG. 7 shows a ball screw device 1 of a third example of the embodiment of the present disclosure.
  • the side surface on one side in the axial direction of the carrier 11a that constitutes the screw shaft 2a is not provided with the projecting portion 16 (see FIG. 2, etc.) that was provided in the screw shaft 2 in the first example.
  • One side surface of the carrier 11a in the axial direction is a flat surface that exists on a virtual plane perpendicular to the central axis of the carrier 11a (screw shaft 2a).
  • the side surface of the outer ring 25 on one side in the axial direction is offset to the other side in the axial direction from the side surface of the carrier 11a on one side in the axial direction.
  • the axial width dimension of the carrier 11a (screw shaft 2a) can be shortened. Therefore, the size of the ball screw device 1 can be reduced.
  • Other configurations and effects are the same as those of the first example.
  • FIG. 8 shows a ball screw device 1 of a fourth example of the embodiment of the present disclosure.
  • the carrier 11b that constitutes the screw shaft 2b has a carrier hollow portion 39 that is open to one side surface in the axial direction in the radial center portion (inside).
  • the carrier hollow portion 39 has a cylindrical inner space.
  • the inner diameter of the carrier hollow portion 39 is constant over the axial direction and is smaller than the diameter of an imaginary circle passing through the radially inner end of each of the plurality of support holes 15 .
  • a bottom surface 40 of the carrier hollow portion 39 is located on one side in the axial direction of the side surface of the carrier 11b on the other side in the axial direction.
  • the inner diameter of the carrier hollow portion can also be varied depending on the axial position. That is, the carrier hollow portion can also be configured by a stepped hole.
  • the threaded portion 10a that constitutes the threaded shaft 2b has an axially long threaded hollow portion 41 that is open to the other end face in the axial direction in the radial center portion (inside) thereof.
  • the screw hollow portion 41 is arranged coaxially with the carrier hollow portion 39 and has a cylindrical inner space.
  • the inner diameter of the threaded hollow 41 is constant in the axial direction and smaller than the inner diameter of the carrier hollow 39 .
  • the inner diameter of the threaded hollow portion can also be varied depending on the axial position. That is, the screw hollow portion can also be configured by a stepped hole.
  • the threaded hollow portion 41 is formed over the entire length of the threaded portion 10a, and one axial end of the threaded hollow portion 41 reaches the other axial side of the carrier 11b.
  • the threaded cavity 41 opens into the bottom surface 40 of the carrier cavity 39 . Therefore, the carrier hollow portion 39 and the screw hollow portion 41 communicate with each other in the axial direction.
  • the carrier hollow portion 39 is formed in the radial center portion of the carrier 11b, and the screw hollow portion 41 is formed in the radial center portion of the screw portion 10a, so that the weight of the screw shaft 2b can be reduced. be able to. Further, since the carrier hollow portion 39 and the threaded hollow portion 41 are communicated in the axial direction, the carrier hollow portion 39 and the threaded hollow portion 41 can be used as passages for lubricating oil, air, and the like. Other configurations and effects are the same as those of the first example.
  • the carrier hollow portion 39 and the screw hollow portion 41 are machined, as in the first example, using the screw-side center hole 13 and the carrier-side center hole 19 to form the shaft-side ball screw groove 12, the inner ring raceway 14, and the It can be performed after processing the support hole 15 . That is, the carrier hollow portion 39 and the screw hollow portion 41 can be formed by cutting and grinding the intermediate material 35 after the forging process and before the rolling process when manufacturing the screw shaft 2b. can. However, in the forging process, a recess having a shape similar to the carrier hollow portion 39 and a hole having a shape similar to the screw hollow portion 41 are formed, and the shapes of the recess and the hole are adjusted by cutting. , the carrier cavity 39 and the threaded cavity 41 can also be formed.
  • FIG. 9 shows an example of a structure in which the ball screw device 1 and the planetary speed reduction mechanism 8 of the fifth example of the embodiment of the present disclosure are combined.
  • a carrier hollow portion 39 is formed in the carrier 11b.
  • the screw hollow portion 41 (see FIG. 8) is not formed in the threaded portion 10 in this example.
  • the tip of the motor shaft 34a of the electric motor 6 (the end on the other side in the axial direction) is inserted inside the carrier hollow portion 39 .
  • the portion of the motor shaft 34 a that protrudes to the other side in the axial direction from the sun gear 30 is inserted inside the carrier hollow portion 39 .
  • a radial needle bearing (C&R) 42 is arranged between the outer peripheral surface of the tip portion of the motor shaft 34 a and the inner peripheral surface of the carrier hollow portion 39 .
  • the tip of the motor shaft 34a is rotatably supported with respect to the carrier 11a using the radial needle bearing 42.
  • a radial roller bearing, sliding bearing, or the like can also be used.
  • the tip of the motor shaft 34a can be rotatably supported with respect to the carrier 11a so that the motor shaft 34a can be held on both sides. Therefore, the degree of coaxiality between the motor shaft 34a and the screw shaft 2c can be increased, and the meshing accuracy between the sun gear 30 and the planetary gears 31 can be increased.
  • Other configurations and effects are the same as those of the first and fourth examples.
  • FIG. 10 shows the ball screw device 1 of the sixth example of the embodiment of the present disclosure.
  • the carrier 11c constituting the screw shaft 2e has one side surface in the axial direction on a virtual plane perpendicular to the central axis of the carrier 11c (screw shaft 2e), like the carrier 11a of the third example. It is assumed to be a flat surface.
  • the axial position of the side surface on one axial side of the carrier 11c and the axial position of the side surface on the one axial side of the outer ring 25 are aligned. That is, in this example, the one axial side surface of the carrier 11c and the one axial side surface of the outer ring 25 are arranged on the same virtual plane perpendicular to the central axis of the carrier 11c (screw shaft 2e). ing.
  • the axial position of the side surface on the other axial side of the carrier 11c and the axial position of the side surface on the other axial side of the outer ring 25 are aligned.
  • the side surface of the carrier 11c on the other side in the axial direction can be offset from the side surface of the outer ring 25 on the other side in the axial direction to the other side in the axial direction or to the one side in the axial direction.
  • Other configurations and effects are the same as those of the first and third examples.
  • the circulation groove is formed directly on the inner peripheral surface of the nut, but the circulation groove is formed in a circulation component (for example, a top) separate from the nut.
  • the circulator can also be fixed to the nut.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Manufacturing & Machinery (AREA)
  • Transmission Devices (AREA)
  • Rolling Contact Bearings (AREA)
  • Forging (AREA)
  • Retarders (AREA)
  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
PCT/JP2022/045691 2022-01-05 2022-12-12 ボールねじ装置およびねじ軸の製造方法 Ceased WO2023132190A1 (ja)

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CN202280015119.9A CN116917644A (zh) 2022-01-05 2022-12-12 滚珠丝杠装置以及螺纹轴的制造方法
JP2023522792A JP7338810B1 (ja) 2022-01-05 2022-12-12 ボールねじ装置およびねじ軸の製造方法
US18/290,108 US12222023B2 (en) 2022-01-05 2022-12-12 Ball screw device and manufacturing method of screw shaft
EP22918776.0A EP4279766B1 (en) 2022-01-05 2022-12-12 Ball screw device and method for manufacturing screw shaft

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JP7552233B2 (ja) * 2020-10-13 2024-09-18 日本精工株式会社 ボールねじ装置
JP7493016B2 (ja) * 2021-12-07 2024-05-30 ビーダブリュアイ（シャンハイ）カンパニー リミテッド 流体で浸されたボールねじを有する圧力平衡化ｐｓｕピストンを備えるブレーキ・バイ・ワイヤ・モジュールおよびバックアップ・ポンプ・アセンブリ
CN119747536B (zh) * 2024-12-12 2026-03-24 江西哈迪威实业有限公司 一种用于螺杆加工的螺杆进给装置
CN120078466B (zh) * 2025-04-25 2025-08-19 北京天星医疗股份有限公司 外排锚钉用植入装置及植入系统

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