JP2013170695A - Cross spider type universal joint and method of manufacturing cross spider for universal joint - Google Patents

Cross spider type universal joint and method of manufacturing cross spider for universal joint Download PDF

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Publication number
JP2013170695A
JP2013170695A JP2012037146A JP2012037146A JP2013170695A JP 2013170695 A JP2013170695 A JP 2013170695A JP 2012037146 A JP2012037146 A JP 2012037146A JP 2012037146 A JP2012037146 A JP 2012037146A JP 2013170695 A JP2013170695 A JP 2013170695A
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Prior art keywords
shaft
cross
universal joint
portions
base
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JP2012037146A
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JP5978647B2 (en
Inventor
Seiichi Moriyama
誠一 森山
Atsushi Maeda
篤志 前田
Yasushi Shigeta
泰志 重田
Kiyoshi Sadakata
清 定方
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NSK Ltd
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NSK Ltd
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    • 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
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/16—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts
    • F16D3/26—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected
    • F16D3/38—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected with a single intermediate member with trunnions or bearings arranged on two axes perpendicular to one another
    • F16D3/382—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected with a single intermediate member with trunnions or bearings arranged on two axes perpendicular to one another constructional details of other than the intermediate member
    • F16D3/385—Bearing cup; Bearing construction; Bearing seal; Mounting of bearing on the intermediate member
    • 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
    • F16C33/72—Sealings
    • F16C33/76—Sealings of ball or roller bearings
    • F16C33/78—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members
    • F16C33/7803—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members suited for particular types of rolling bearings
    • F16C33/7809—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members suited for particular types of rolling bearings for needle roller bearings
    • 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
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/16—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts
    • F16D3/26—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected
    • F16D3/38—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected with a single intermediate member with trunnions or bearings arranged on two axes perpendicular to one another
    • F16D3/40—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected with a single intermediate member with trunnions or bearings arranged on two axes perpendicular to one another with intermediate member provided with two pairs of outwardly-directed trunnions on intersecting axes
    • F16D3/41—Hooke's joints or other joints with an equivalent intermediate member to which each coupling part is pivotally or slidably connected with a single intermediate member with trunnions or bearings arranged on two axes perpendicular to one another with intermediate member provided with two pairs of outwardly-directed trunnions on intersecting axes with ball or roller bearings
    • 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
    • F16C21/00—Combinations of sliding-contact bearings with ball or roller bearings, for exclusively rotary movement
    • F16C21/005—Combinations of sliding-contact bearings with ball or roller bearings, for exclusively rotary movement the external zone of a bearing with rolling members, e.g. needles, being cup-shaped, with or without a separate thrust-bearing disc or ring, e.g. for universal joints
    • 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
    • F16D2300/00—Special features for couplings or clutches
    • F16D2300/08—Details or arrangements of sealings not provided for in group F16D3/84

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

PROBLEM TO BE SOLVED: To materialize a structure which is easy both to secure reliability and durability and to reduce size and weight by increasing breaking strength when large load is applied.SOLUTION: A basal end outer peripheral surface of each shaft 14 constituting a cross spider 11a and a stepped surface 30 serving as an external face of a coupling base 15 are connected via concaved planes 31a whose cross sections are partially arcuate, respectively. A radius of curvature of the cross section of these concaved planes 31a is made larger on the side of a distal half 33 connecting with an outer peripheral surface of each shaft 14 and made smaller on the side of a basal half 32 connecting with the stepped surface 30. With such a constitution, the radius of curvature R of the cross section of a part in the concaved planes 31a where stress occurring when transmitting torque is likely to increase is made to be large, thereby making damage such as cracks hard to occur on the basal end of each shaft 14, without unnecessarily enlarging a longitudinal dimension of each shaft 14.

Description

この発明は、例えばステアリングシャフトの動きをステアリングギヤに伝達する為、自動車のステアリング装置に組み込んだ状態で使用する十字軸式自在継手の改良に関する。具体的には、十字軸を構成する４本の各軸部の基端部の強度を向上させる事により、この十字軸を組み込んだ十字軸式自在継手の信頼性及び耐久性の向上、或いは小型・軽量化を可能にするものである。   The present invention relates to an improvement in a cross shaft type universal joint that is used in a state where it is incorporated in a steering device of an automobile, for example, in order to transmit the movement of a steering shaft to a steering gear. Specifically, by improving the strength of the base end portion of each of the four shafts constituting the cross shaft, the reliability and durability of the cross shaft universal joint incorporating this cross shaft is improved, or the size is reduced.・ It is possible to reduce the weight.

自動車のステアリング装置は、例えば特許文献１に記載されている如く、図５に示す様に構成している。運転者が操作するステアリングホイール１の動きは、ステアリングシャフト２、自在継手３ａ、中間シャフト４、別の自在継手３ｂを介して、ステアリングギヤユニット５の入力軸６に伝達される。そして、このステアリングギヤユニット５に内蔵したラック＆ピニオン機構により左右１対のタイロッド７、７を押し引きし、左右１対の操舵輪（一般的には前輪）に、前記ステアリングホイール１の操作量に応じて、適切な舵角を付与する様に構成している。尚、前記中間シャフト４として一般的には、図６に示す様に、アウタシャフト８とインナシャフト９との一端部同士をセレーション係合させる事により、トルクの伝達を可能に、但し、衝突事故の際に全長を収縮可能に構成したものを使用している。前記両自在継手３ａ、３ｂは、前記両シャフト８、９の他端部に結合している。   An automobile steering device is configured as shown in FIG. The movement of the steering wheel 1 operated by the driver is transmitted to the input shaft 6 of the steering gear unit 5 via the steering shaft 2, the universal joint 3a, the intermediate shaft 4, and another universal joint 3b. A pair of left and right tie rods 7 and 7 are pushed and pulled by a rack and pinion mechanism built in the steering gear unit 5, and the amount of operation of the steering wheel 1 is applied to a pair of left and right steering wheels (generally, front wheels). Depending on the situation, an appropriate rudder angle is provided. As shown in FIG. 6, the intermediate shaft 4 is generally capable of transmitting torque by serration engagement between one end portions of the outer shaft 8 and the inner shaft 9, provided that a collision accident occurs. In this case, the one whose total length can be contracted is used. The universal joints 3a and 3b are coupled to the other end portions of the shafts 8 and 9.

上述の様なステアリング装置に組み込む自在継手として一般的には、カルダン継手と呼ばれる十字軸継手が、広く使用されている。図７〜８は、前記特許文献１に記載される等により、従来から広く知られている自在継手３の１例を示している。尚、図７〜８に示した構造は、振動の伝達を防止する、所謂防振継手であるが、本発明の対象となる自在継手は、必ずしも防振構造を具備する必要はない。そこで、以下の説明は防振構造を省略して、自在継手３の本体部分の構造に就いて行う。   In general, a cross joint called a cardan joint is widely used as a universal joint incorporated in the steering apparatus as described above. FIGS. 7-8 has shown an example of the universal joint 3 known widely conventionally, for example by describing in the said patent document 1. FIG. The structure shown in FIGS. 7 to 8 is a so-called vibration-proof joint that prevents transmission of vibration. However, the universal joint that is the subject of the present invention does not necessarily have a vibration-proof structure. Therefore, the following description will be made on the structure of the main body portion of the universal joint 3 while omitting the vibration-proof structure.

この自在継手３は、十分な剛性を有する金属材によりそれぞれが二又状に形成された１対のヨーク１０ａ、１０ｂと、軸受鋼の如き合金鋼等の硬質金属により造られた十字軸１１とから構成される。これら両ヨーク１０ａ、１０ｂの両端部には、互いに同心の円孔１２、１２を形成している。そしてこれら各円孔１２、１２に、やはり軸受鋼、肌焼鋼等の硬質金属製の板材により有底円筒状に造られた軸受カップ１３、１３を、互いの開口を対向させた状態で内嵌固定している。又、前記十字軸１１は、１対の柱部の中間部同士を互いに直交させた如き形状を有し、それぞれが円柱状である、４箇所の各軸部１４、１４を有する。即ち、中心部に設けた結合基部１５の円周方向等間隔４箇所位置に、それぞれ前記各軸部１４、１４の基端部を結合固定している。これら各軸部１４、１４の中心軸は、同一平面上に存在する。   The universal joint 3 includes a pair of yokes 10a and 10b each formed in a bifurcated shape by a metal material having sufficient rigidity, and a cross shaft 11 made of a hard metal such as an alloy steel such as bearing steel. Consists of Concentric circular holes 12 and 12 are formed at both ends of both yokes 10a and 10b. And in these circular holes 12 and 12, bearing cups 13 and 13 made of a hard metal plate material such as bearing steel and case-hardened steel are formed in a state where the openings are opposed to each other. It is fitted and fixed. The cross shaft 11 has a shape such that the middle portions of a pair of column portions are orthogonal to each other, and each has four shaft portions 14 and 14 each having a cylindrical shape. In other words, the base end portions of the shaft portions 14 and 14 are coupled and fixed at four positions at equal intervals in the circumferential direction of the coupling base portion 15 provided in the central portion. The central axes of these shaft portions 14 and 14 exist on the same plane.

この様な各軸部１４、１４の軸方向中間部乃至先端部は、前記各軸受カップ１３、１３内に挿入している。そして、これら各軸受カップ１３、１３の内周面と前記各軸部１４、１４の先半部外周面との間に、ニードル軸受等のラジアル軸受１６、１６を設け、前記十字軸１１に対して前記両ヨーク１０ａ、１０ｂが、軽い力で揺動変位する様にしている。この様に構成する為、これら両ヨーク１０ａ、１０ｂの中心軸同士が一致しない状態でも、これら両ヨーク１０ａ、１０ｂの間で回転力の伝達を、伝達ロスを僅少に抑えた状態で行える。   The axial direction intermediate part thru | or the front-end | tip part of each such shaft part 14 and 14 are inserted in each said bearing cup 13 and 13. FIG. Then, radial bearings 16, 16 such as needle bearings are provided between the inner peripheral surfaces of the bearing cups 13, 13 and the front half outer peripheral surfaces of the shaft portions 14, 14. Thus, the yokes 10a and 10b are oscillated and displaced with a light force. Due to such a configuration, even when the central axes of the yokes 10a and 10b do not coincide with each other, the rotational force can be transmitted between the yokes 10a and 10b with a little transmission loss.

上述の様な自在継手３を車室外に設置する（図５で下側の自在継手３ｂとして利用する）場合には、前記十字軸１１を構成する前記各軸部１４、１４の基端部（前記結合基部１５側の端部）と前記各軸受カップ１３、１３の開口部との間に、それぞれシールリング１７、１７を設ける。そして、これら各シールリング１７、１７により、前記各ラジアル軸受１６、１６の設置部分に泥水等が進入するのを防止し、前記自在継手３の耐久性の確保を図る。前記各シールリング１７、１７はそれぞれ、金属製で円環状の芯金１８と、ゴムの如きエラストマー製の弾性材１９とから成る。このうちの芯金１８は、軟鋼板等の金属板を曲げ形成する事により、断面Ｌ字形で全体を円環状に形成したもので、円輪部２０と、この円輪部２０の内周縁側から前記各軸部１４、１４の先端側に向けて折れ曲がった円筒部２１とから成る、断面Ｌ字形としている。又、前記弾性材１９は、前記芯金１８を包埋する事でこの芯金１８により補強された基部２２と、この基部２２から延出した、それぞれが特許請求の範囲に記載したシールリップである、ラジアルシールリップ２３及びスラストシールリップ２４から成る。   When the universal joint 3 as described above is installed outside the passenger compartment (used as the lower universal joint 3b in FIG. 5), the base end portions of the shaft portions 14, 14 constituting the cross shaft 11 ( Seal rings 17 and 17 are provided between the end of the coupling base portion 15 and the opening portions of the bearing cups 13 and 13, respectively. The seal rings 17 and 17 prevent muddy water and the like from entering the installed portions of the radial bearings 16 and 16, thereby ensuring the durability of the universal joint 3. Each of the seal rings 17 and 17 includes a metal-made annular cored bar 18 and an elastic material 19 made of an elastomer such as rubber. Of these, the metal core 18 is formed by bending a metal plate such as a mild steel plate to form an annular shape as a whole with an L-shaped cross section, and the inner peripheral edge side of the annular portion 20. The cylindrical portion 21 is bent toward the tip side of each of the shaft portions 14 and 14, and has an L-shaped cross section. The elastic member 19 includes a base portion 22 reinforced by embedding the core metal 18 and a base lip extending from the base portion 22, each of which is a seal lip described in the claims. It consists of a radial seal lip 23 and a thrust seal lip 24.

それぞれがこの様な構成を有する、前記各シールリング１７、１７は、前記芯金１８を包埋した基部を前記各軸部１４、１４の基端部に締り嵌めで（弾性材１９の一部を弾性変形させた状態で）外嵌する事により、これら各軸部１４、１４の基端部に、嵌合部のシール性を確保した状態で支持している。この様にこれら各軸部１４、１４の基端部に前記各シールリング１７、１７を支持し、前記十字軸１１と前記各軸受カップ１３、１３とを組み合わせた状態で、前記各シールリップ２３、２４のうちのラジアルシールリップ２３のシール縁は、前記各軸受カップ１３、１３の外周面のうちで開口寄り端部に、全周に亙り弾性的に当接する。又、前記スラストシールリップ２４のシール縁は、前記各軸受カップ１３、１３の開口部に形成された内向鍔部２５の外面（前記結合基部１５に対向する面）に、全周に亙り弾性的に当接する。   Each of the seal rings 17, 17 each having such a configuration has a base portion in which the cored bar 18 is embedded in a base end portion of each of the shaft portions 14, 14 (part of the elastic material 19). By being externally fitted (in a state of being elastically deformed), the base end portions of these shaft portions 14 and 14 are supported in a state in which the sealing property of the fitting portions is ensured. In this manner, the seal rings 17 and 17 are supported on the base end portions of the shaft portions 14 and 14, and the seal lips 23 are combined with the cross shaft 11 and the bearing cups 13 and 13. 24, the seal edge of the radial seal lip 23 elastically abuts over the entire circumference of the outer peripheral surface of each of the bearing cups 13 and 13 at the end closer to the opening. Further, the seal edge of the thrust seal lip 24 is elastic over the entire circumference on the outer surface of the inward flange portion 25 formed on the opening of each of the bearing cups 13 and 13 (the surface facing the coupling base portion 15). Abut.

更に、前記各軸部１４、１４の中心部にはそれぞれ有底の挿入孔２６、２６を、これら各軸部１４、１４の先端面に開口する状態で、前記各軸部１４、１４の軸方向に形成している。そして、これら各挿入孔２６、２６の内側に、合成樹脂製のピン２７、２７を挿入している。これら各ピン２７、２７は、前記各軸受カップ１３、１３と前記各軸部１４、１４との間で突っ張る事により、これら各軸受カップ１３、１３の開口端部と前記基部２２との距離が縮まり過ぎる事を防止する。そして、前記各シーリング１５、１５のスラストシールリップ２４が過度に圧縮されたり、反対に圧縮量が低下し過ぎる事を防止する。即ち、自在継手３の使用時に前記十字軸１１と前記各軸受カップ１３、１３との間に加わるスラスト荷重に基づき、スラスト荷重作用側（アンカ側）のシールリング１７が過度に圧縮されて耐久性が損なわれ、反対側（反アンカ側）のシールリング１７の圧縮量が低下し過ぎて、このシールリング１７によるシール性が損なわれる事を防止する。   Furthermore, the shafts of the shafts 14, 14 are opened in the state in which the bottomed insertion holes 26, 26 are opened at the front end surfaces of the shafts 14, 14 at the center of the shafts 14, 14, respectively. It is formed in the direction. Then, synthetic resin pins 27 and 27 are inserted inside the insertion holes 26 and 26, respectively. The pins 27 and 27 are stretched between the bearing cups 13 and 13 and the shafts 14 and 14 so that the distance between the opening end of the bearing cups 13 and 13 and the base 22 is increased. Preventing it from shrinking too much. Then, the thrust seal lip 24 of each of the seals 15, 15 is prevented from being excessively compressed, and conversely, the amount of compression is prevented from being excessively reduced. That is, when the universal joint 3 is used, the thrust load acting side (anchor side) seal ring 17 is excessively compressed on the basis of the thrust load applied between the cross shaft 11 and the bearing cups 13, 13. Is prevented, and the amount of compression of the seal ring 17 on the opposite side (anti-anchor side) is excessively reduced, thereby preventing the sealing performance of the seal ring 17 from being impaired.

但し、上述の様なピン２７、２７を設けない、十字軸式の自在継手に就いても、従来から広く知られている。即ち、図９に示した従来構造の第２例の如く、軸受カップ１３ａの底部２８の内面中央寄り部分に突条２９、２９を形成し、これら各突条２９、２９の先端縁を、十字軸１１を構成する各軸部１４の先端面に当接させている。この様な構造によっても、自在継手の構成部材の寸法精度及び組立精度を確保さえすれば、前記軸受カップ１３ａと前記各軸部１４との間に設けるシールリング１７の圧縮量を適性範囲に保持できる。   However, a cross shaft type universal joint that does not include the pins 27 and 27 as described above is also widely known. That is, as in the second example of the conventional structure shown in FIG. 9, the ridges 29 and 29 are formed in the portion near the center of the inner surface of the bottom portion 28 of the bearing cup 13a, and the leading edges of these ridges 29 and 29 are cross-shaped. It is made to contact | abut to the front end surface of each axial part 14 which comprises the axis | shaft 11. FIG. Even with such a structure, the compression amount of the seal ring 17 provided between the bearing cup 13a and each shaft portion 14 can be maintained within an appropriate range as long as the dimensional accuracy and assembly accuracy of the components of the universal joint are ensured. it can.

何れの構造の場合でも、十字軸１１を構成する各軸部１４、１４の基端部にシールリング１７、１７を、締り嵌めで外嵌支持する。そして、これら各軸部１４、１４に対するこれら各シールリング１７、１７の位置決めを適正にする事が、十字軸式の自在継手３の変位抵抗を抑えると共に、これら各シールリング１７、１７のシール性能を確保する面から重要になる。これらの事を考慮すると、図７〜９に示した従来構造では、十字軸式自在継手に関して、十分な信頼性及び耐久性を確保しつつ、小型・軽量化を図る事が難しい。この点に就いて、図１０を参照しつつ説明する。   In any structure, the seal rings 17 and 17 are externally supported by interference fitting at the base end portions of the shaft portions 14 and 14 constituting the cross shaft 11. The proper positioning of the seal rings 17 and 17 with respect to the shaft portions 14 and 14 suppresses the displacement resistance of the cruciform universal joint 3 and the sealing performance of the seal rings 17 and 17. It becomes important from the aspect of securing. In consideration of these matters, in the conventional structure shown in FIGS. 7 to 9, it is difficult to reduce the size and weight of the cross shaft universal joint while ensuring sufficient reliability and durability. This point will be described with reference to FIG.

十字軸１１を構成する各軸部１４のうち、軸方向中間部乃至先端部である、図１０のＬ範囲部分は、ラジアル軸受１６（図７〜９参照）の内輪軌道としての役目を有する為、超仕上等の研削加工を施す。十字軸式自在継手によるトルク伝達は、前記ラジアル軸受１６を介して行うので、伝達可能なトルク（トルク容量）を確保する必要上、前記Ｌ範囲の長さ寸法は或る程度必要である。又、このＬ範囲で表された内輪軌道部分よりも基端寄り部分には、シールリング１７の基部２２を外嵌支持する。この支持力を十分に確保する為、及び、この嵌合部のシール性を確保する為には、前記各軸部１４と前記基部２２との嵌合幅Ｗを、或る程度以上確保する必要がある。又、これら基部２２と各軸部１４とを嵌合させた状態で、この基部２２に包埋した芯金１８の円輪部２０の片面を、前記十字軸１１を構成する、前記結合基部１５の外面である段差面３０に当接させて、前記各軸部１４の軸方向に関する、前記シールリング１７の位置決めを図る。この位置決めの精度を確保する為には、前記円輪部２０の片面と前記段差面３０との当接状態を安定させる必要上、これら両面同士を均一に当接させる必要がある。   Of the shaft portions 14 constituting the cross shaft 11, the L range portion in FIG. 10, which is an axial intermediate portion or a tip portion, serves as an inner ring raceway of the radial bearing 16 (see FIGS. 7 to 9). Grinding such as super finishing. Since torque transmission by the cross shaft type universal joint is performed through the radial bearing 16, it is necessary to secure a transmittable torque (torque capacity) and a certain length dimension in the L range. Further, the base portion 22 of the seal ring 17 is externally supported so as to be closer to the base end than the inner ring raceway portion represented by the L range. In order to sufficiently secure the supporting force and to ensure the sealing performance of the fitting portion, it is necessary to secure the fitting width W between the shaft portions 14 and the base portion 22 to some extent. There is. Further, in a state in which the base portion 22 and the shaft portions 14 are fitted, one side of the annular portion 20 of the cored bar 18 embedded in the base portion 22 constitutes the cross shaft 11 and the coupling base portion 15. The seal ring 17 is positioned with respect to the axial direction of each of the shaft portions 14 by being brought into contact with the step surface 30 which is the outer surface of the shaft portion 14. In order to secure the positioning accuracy, it is necessary to make the both surfaces contact uniformly with each other in order to stabilize the contact state between one surface of the annular portion 20 and the step surface 30.

以上の事を考慮し、しかも、前記十字軸１１の全長を少しでも短く抑えて、この十字軸１１を組み込んだ自在継手３（図５〜９参照）の小型・軽量化を図る為に従来は、図１０に示す様に、前記各軸部１４の外周面と前記段差面３０とを連続させる凹曲面３１の曲率半径を小さくしていた。一方、前記自在継手３によりトルクを伝達する際に、前記各軸部１４と前記結合基部１５との連続部には、この結合基部１５に対しこの各軸部１４を倒す方向のモーメントが、繰り返し加わる。そして、このモーメントにより、前記凹曲面３１部分に応力が加わる。この応力の大きさは、この凹曲面３１の断面形状の曲率半径が小さい程、又、前記各軸部１４の外径が小さい程、それぞれ大きくなる。従って、前記凹曲面３１部分に亀裂等の損傷が発生するのを防止すべく、この凹曲面３１部分に加わる応力を低く抑える為には、前記凹曲面３１の断面形状の曲率半径を大きくするか、又は、前記各軸部１４の外径を大きくする必要があり、自在継手３の小型・軽量化を図る面からは不利になる。   In view of the above, in order to reduce the overall length of the cross shaft 11 as much as possible and to reduce the size and weight of the universal joint 3 incorporating the cross shaft 11 (see FIGS. 5 to 9), As shown in FIG. 10, the radius of curvature of the concave curved surface 31 that connects the outer peripheral surface of each shaft portion 14 and the stepped surface 30 is reduced. On the other hand, when torque is transmitted by the universal joint 3, moments in the direction in which the shaft portions 14 are inclined with respect to the coupling base portion 15 are repeatedly applied to the continuous portions of the shaft portions 14 and the coupling base portion 15. Join. Then, stress is applied to the concave curved surface 31 portion by this moment. The magnitude of this stress increases as the radius of curvature of the cross-sectional shape of the concave curved surface 31 decreases and as the outer diameter of each shaft portion 14 decreases. Therefore, in order to suppress the stress applied to the concave curved surface 31 portion in order to prevent the concave curved surface 31 portion from being damaged such as a crack, the radius of curvature of the sectional shape of the concave curved surface 31 should be increased. Alternatively, it is necessary to increase the outer diameter of each shaft portion 14, which is disadvantageous from the viewpoint of reducing the size and weight of the universal joint 3.

特許文献２には、十字軸の各軸部の全長を確保して、この各軸部がヨークの円孔から抜け出難くする為、この各軸部の先端部に面取り部を設ける発明が記載されている。この様な特許文献２に記載された発明の構造によれば、大きなトルク伝達時に於ける、十字軸とヨークとの分離防止を図るべく、この十字軸を構成する各軸部の全長を長くした場合でも、この十字軸をヨークに組み込む事ができる。但し、前記特許文献２に記載された発明の構造にしても、前記図１０により説明した様な理由で、大きな負荷が加わった場合に於ける破壊強度（大負荷時破壊強度）を大きくし難く、信頼性及び耐久性の確保と、小型・軽量化との両立を図り難い。   Patent Document 2 describes an invention in which a chamfered portion is provided at the tip of each shaft portion in order to secure the full length of each shaft portion of the cross shaft and make it difficult for each shaft portion to come out of the circular hole of the yoke. ing. According to the structure of the invention described in Patent Document 2 as described above, in order to prevent the cross shaft and the yoke from being separated when transmitting a large torque, the total length of each shaft portion constituting the cross shaft is increased. Even in this case, this cross shaft can be incorporated into the yoke. However, even in the structure of the invention described in Patent Document 2, it is difficult to increase the breaking strength (breaking strength under a large load) when a large load is applied for the reason described with reference to FIG. Therefore, it is difficult to achieve both reliability and durability while reducing size and weight.

特開２０１０−１８１０１６号公報JP 2010-181016 A 特開平１１−０３７１７１号公報JP 11-037171 A

本発明は、上述の様な事情に鑑みて、大負荷時破壊強度を大きくして、信頼性及び耐久性の確保と、小型・軽量化との両立を図り易い構造を実現すべく発明したものである。   In view of the circumstances as described above, the present invention was invented to increase the breaking strength under heavy load, and to realize a structure that facilitates both ensuring reliability and durability, and reducing size and weight. It is.

本発明の十字軸式自在継手、並びに、本発明の製造方法の対象となる十字軸を組み込んだ十字軸式自在継手は、１対のヨークと、４個の円孔と、４個の軸受カップと、十字軸と、４組のラジアル軸受とを備える。
このうちの１対のヨークは、それぞれが二股状に形成されている。
又、前記各円孔は、これら両ヨークの両端部に、互いに同心に形成されている。
又、前記各軸受カップは、それぞれが有底円筒状で、互いの開口を対向させた状態で、前記各円孔の内側に内嵌固定されている。
又、前記十字軸は、結合基部の外周面に４本の各軸部を放射状に固設して成る。そして、これら各軸部を前記各軸受カップ内に挿入した状態で、前記両ヨークと組み合わされている。
更に、前記各ラジアル軸受は、前記各軸部の外周面と前記各軸受カップの内周面との間に設けられている。 The cruciform universal joint of the present invention and the cruciform universal joint incorporating the cruciform shaft that is the object of the manufacturing method of the present invention are a pair of yokes, four circular holes, and four bearing cups. And a cross shaft and four sets of radial bearings.
Each of the pair of yokes is formed in a bifurcated shape.
The circular holes are concentrically formed at both ends of the yokes.
Each bearing cup has a bottomed cylindrical shape and is fitted and fixed inside each of the circular holes with the openings facing each other.
The cross shaft is formed by radially fixing four shaft portions on the outer peripheral surface of the coupling base. The shafts are combined with the yokes in a state where the shafts are inserted into the bearing cups.
Furthermore, each said radial bearing is provided between the outer peripheral surface of each said axial part, and the inner peripheral surface of each said bearing cup.

特に、本発明のうちの、請求項１に記載した十字軸式自在継手に於いては、前記十字軸を構成する前記各軸部の基端部外周面と前記結合基部の外面である段差面とを、それぞれ断面形状が円弧形で、曲率半径が途中で変化する凹曲面により連続させている。そして、これら各凹曲面のうちの前記段差面寄り部分の曲率半径よりも、前記各軸部寄り部分の曲率半径を大きくしている。   Particularly, in the cross shaft type universal joint according to claim 1 of the present invention, the stepped surface which is the outer peripheral surface of the base end portion of each shaft portion and the outer surface of the coupling base portion constituting the cross shaft. Are continuously connected by a concave curved surface whose cross-sectional shape is an arc shape and whose radius of curvature changes midway. Of these concave curved surfaces, the radius of curvature of the portion near the shaft portion is made larger than the radius of curvature of the portion near the step surface.

この様な本発明の十字軸式自在継手を実施する場合、具体的には、例えば請求項２に記載した発明の様に、前記十字軸を構成する前記各軸部と前記各軸受カップとを、これら各軸部の軸方向に関する相対変位を実質的に抑えた状態で（構成部材の弾性変形に基く僅かな相対変位を除き阻止した状態で）組み合わせる。又、４個のシールリングを、前記各軸部の基端部にそれぞれの基部を外嵌支持した状態で、これら各軸部の基端部と前記各軸受カップの開口部との間に設ける。前記各シールリングは、金属製で円環状の芯金と、この芯金を包埋する事で補強された基部及びこの基部から延出したシールリップを備えた弾性材とから構成する。そして、前記各シールリングを、前記基部を前記各軸部の基端部に締り嵌めで外嵌支持すると共に、前記各シールリップを前記各軸受カップの外面に全周に亙って当接させた状態で、前記十字軸と前記両ヨークとの間に組み付ける。
或いは、請求項３に記載した発明の様に、前記十字軸を構成する前記各軸部と前記各軸受カップとを、これら各軸部の軸方向に関する相対変位を可能に組み合わせる。そして、これら各軸部に、弾性材製のシールリングを外嵌し、これら各シールリングを、前記各軸受カップの開口部側端面と、前記十字軸の段差面との間で、軸方向に関して弾性的に圧縮した状態で挟持する。 When implementing such a cross shaft type universal joint of the present invention, specifically, as in the invention described in claim 2, for example, the shaft portions and the bearing cups constituting the cross shaft are connected to each other. These are combined in a state in which the relative displacement in the axial direction of each of the shaft portions is substantially suppressed (in a state where it is prevented except for a slight relative displacement based on the elastic deformation of the constituent members). Also, four seal rings are provided between the base end portions of the shaft portions and the opening portions of the bearing cups in a state where the base portions are fitted and supported on the base end portions of the shaft portions. . Each of the seal rings is made of a metal-made annular cored bar, a base reinforced by embedding the cored bar, and an elastic material having a seal lip extending from the base. Then, each seal ring is externally supported by an interference fit to the base end portion of each shaft portion, and each seal lip is brought into contact with the outer surface of each bearing cup over the entire circumference. In this state, it is assembled between the cross shaft and the yokes.
Alternatively, as in the invention described in claim 3, the shaft portions constituting the cross shaft and the bearing cups are combined so as to allow relative displacement in the axial direction of the shaft portions. Then, a seal ring made of an elastic material is externally fitted to each of these shaft portions, and each of these seal rings is between the opening side end surface of each bearing cup and the step surface of the cross shaft with respect to the axial direction. It is clamped in an elastically compressed state.

又、請求項４に記載した、自在継手用十字軸の製造方法は、前記各軸部の外周面と前記結合基部の外面である段差面との連続部に旋削による仕上加工を施す際に、切削部の形状が、曲率半径が途中で変化する部分凸円弧状で、この凸円弧の曲率半径がこの切削部の先端側よりも基端側で大きくなった曲面加工部を備えたバイトを使用する。そして、このバイトを前記各軸部に対して、それぞれこれら各軸部の先端側から基端側に向けて変位させる方向に移動させる。この作業により、前記十字軸を構成する前記各軸部の基端部外周面と前記結合基部の外面である段差面との連続部に、それぞれ断面形状が円弧形で、前記段差面寄り部分の曲率半径よりも、前記各軸部寄り部分の曲率半径を大きい凹曲面を形成する。
この様な請求項４に記載した自在継手用十字軸の製造方法を実施する場合に好ましくは、請求項５に記載した発明の様に、前記バイトとして先端縁に直線加工部を設けたものを使用する。そして、前記曲面加工部により前記各凹曲面に仕上加工を施すと同時に、前記直線加工部により前記段差面に仕上加工を施す。 Further, in the method for manufacturing the universal joint cross shaft according to claim 4, when performing a finishing process by turning on a continuous portion between the outer peripheral surface of each shaft portion and the stepped surface which is the outer surface of the coupling base portion, The cutting part has a partially convex arc shape whose radius of curvature changes in the middle, and uses a cutting tool with a curved surface processing part where the radius of curvature of this convex arc is larger on the base end side than on the tip side of this cutting part To do. Then, the cutting tool is moved with respect to each of the shaft portions in a direction of displacing from the distal end side to the proximal end side of each of the shaft portions. As a result of this operation, the cross-sectional shape is an arc shape at the continuous portion between the outer peripheral surface of the base end portion of each shaft portion constituting the cross shaft and the step surface which is the outer surface of the coupling base portion, and the portion near the step surface. A concave curved surface is formed in which the radius of curvature of the portion closer to each shaft portion is larger than the radius of curvature.
When implementing the manufacturing method of the cross joint for universal joints described in claim 4, preferably, as in the invention described in claim 5, the cutting tool provided with a linearly machined portion at the tip edge. use. Then, at the same time that each concave curved surface is finished by the curved surface processing portion, the step surface is finished by the linear processing portion.

前述の様に構成する本発明の十字軸式自在継手によれば、大負荷時破壊強度を大きくして、信頼性及び耐久性の確保と、小型・軽量化との両立を図り易い構造を実現できる。
即ち、本発明の十字軸式自在継手の場合には、十字軸を構成する結合基部の外面である段差面と各軸部の基端部外周面とを、それぞれ断面形状が部分円弧形で、これら各軸部寄り部分の曲率半径を大きくした、凹曲面により連続させている。これら各凹曲面の曲率半径が、前記各軸部寄り部分で大きい事は、トルク伝達時にこれら各軸部に加わる、倒れ方向のモーメントに拘らず、これら各軸部の基端部外周面と段差面との連続部に発生する応力を低く抑えられる事に繋がる。又、前記段差面寄り部分の曲率半径を小さく抑える事は、前記各軸部の軸方向に関する、前記各凹曲面の幅寸法を抑え、これら各軸部の中間部乃至先端部に存在する内輪軌道の軸方向長さ、及び、シールリングを装着可能な部分の軸方向幅を確保できる事に繋がる。この結果、前記各軸部の長さ寸法や外径を特に大きくしなくても、前記連続部に亀裂等の損傷を発生し難くできて（大負荷時破壊強度を大きくして）、前記十字軸を組み込んだ十字軸式自在継手の信頼性及び耐久性を確保できる。言い換えれば、必要とする信頼性及び耐久性を同じとした場合には、前記十字軸の寸法を小さく抑えて、この十字軸を組み込んだ、十字軸式自在継手の小型・軽量化を図れる。
更に、請求項４に記載した発明によれば、上述の様な作用・効果を発揮する、前記各凹曲面を能率良く形成できて、高性能の十字軸式自在継手を低コストで得られる。 The cross shaft universal joint of the present invention configured as described above increases the breaking strength under heavy load, and realizes a structure that can easily achieve both reliability and durability while being compact and lightweight. it can.
That is, in the case of the cruciform universal joint of the present invention, the cross-sectional shape of the step surface, which is the outer surface of the coupling base portion constituting the cruciform shaft, and the base end portion outer peripheral surface of each shaft portion is a partial arc shape. These are made continuous by concave curved surfaces in which the radii of curvature of the portions near the respective shaft portions are increased. The fact that the radius of curvature of each of these concave curved surfaces is large at the portion near each of the shaft portions is a step difference from the outer peripheral surface of the base end portion of each of these shaft portions regardless of the moment in the falling direction applied to each of these shaft portions during torque transmission. The stress generated in the continuous part with the surface can be kept low. Further, to suppress the radius of curvature of the portion near the step surface is to suppress the width dimension of each concave curved surface with respect to the axial direction of each shaft portion, and the inner ring raceway existing at the intermediate portion or the tip portion of each shaft portion. As a result, it is possible to secure the axial length and the axial width of the portion where the seal ring can be attached. As a result, even if the length and outer diameter of each shaft portion are not particularly increased, it is difficult to cause damage such as cracks in the continuous portion (increasing the breaking strength under heavy load), and the cross The reliability and durability of the cross joint universal joint incorporating the shaft can be secured. In other words, when the required reliability and durability are the same, the size of the cross shaft can be kept small, and the cross shaft universal joint incorporating the cross shaft can be reduced in size and weight.
Furthermore, according to the fourth aspect of the present invention, the concave curved surfaces exhibiting the functions and effects as described above can be efficiently formed, and a high-performance cross shaft type universal joint can be obtained at low cost.

本発明の実施の形態の第１例を、十字軸及びシールリングを取り出した状態で示す部分断面図。The fragmentary sectional view which shows the 1st example of embodiment of this invention in the state which took out the cross shaft and the seal ring. 各軸部の基端部外周面と結合基部の外面である段差面との連続部に凹曲面を形成する状態を示す部分断面図。The fragmentary sectional view which shows the state which forms a concave curved surface in the continuous part of the base end part outer peripheral surface of each axial part, and the level | step difference surface which is an outer surface of a joint base. 本発明の技術的範囲に属する凹曲面（Ａ）と、本発明の技術的範囲から外れる凹曲面（Ｂ）（Ｃ）とを示す部分断面図。The partial sectional view which shows the concave curved surface (A) which belongs to the technical scope of this invention, and the concave curved surface (B) (C) which remove | deviates from the technical scope of this invention. 本発明の実施の形態の第２例を示す、図１と同様の図（Ａ）及びシールリングの別例を示す部分断面図（Ｂ）。The figure (A) similar to FIG. 1 which shows the 2nd example of embodiment of this invention, and the fragmentary sectional view (B) which show another example of a seal ring. 自在継手を組み込んだステアリング装置の１例を示す斜視図。The perspective view which shows an example of the steering device incorporating a universal joint. 両端部に十字軸式自在継手を装着した中間シャフトを示す、部分切断側面図。The partial cutting side view which shows the intermediate shaft which attached the cross-shaft type universal joint to both ends. 従来から知られている自在継手の第１例を示す、部分切断側面図。The partial cut side view which shows the 1st example of the universal joint known conventionally. 一部を省略して示す、図７の拡大Ｘ−Ｘ断面図。The expanded XX sectional drawing of FIG. 7 which abbreviate | omits and shows a part. 従来から知られている自在継手の第２例を示す、図８のＹ−Ｙ断面に相当する図。The figure equivalent to the YY cross section of FIG. 8 which shows the 2nd example of the universal joint known conventionally. 従来構造の場合に生じる問題を説明する為の、図１と同様の図。The same figure as FIG. 1 for demonstrating the problem which arises in the case of a conventional structure.

［実施の形態の第１例］
図１〜２は、請求項１、２、４、５に対応する、本発明の実施の形態の第１例を示している。尚、本例の特徴は、十字軸を構成する各軸部の基端部外周面と結合基部の外面である段差面との連続部の形状を工夫する事により、前記十字軸の寸法を大きくせずに、前記各軸部に加わるモーメントに基づいて前記連続部に発生する応力を低く抑えられる構造を実現する点にある。その他の部分の構造及び作用は、前述の図８〜１０に示した従来構造の第２〜３例とほぼ同様であるから、同等部分に関する図示並びに説明は、省略若しくは簡略にし、以下、本例の特徴部分を中心に説明する。 [First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to claims 1, 2, 4, and 5. FIG. The feature of this example is that the dimension of the cross shaft is increased by devising the shape of the continuous portion between the outer peripheral surface of the base end portion of each shaft portion constituting the cross shaft and the stepped surface which is the outer surface of the coupling base portion. In this respect, a structure can be realized in which the stress generated in the continuous portion can be kept low based on the moment applied to each shaft portion. Since the structure and operation of the other parts are almost the same as those of the second to third examples of the conventional structure shown in FIGS. 8 to 10 described above, illustration and explanation of the equivalent parts are omitted or simplified. The description will focus on the features of

本例の場合には、十字軸式の自在継手を構成する十字軸１１ａを構成する各軸部１４の基端部外周面と、結合基部１５の外面の一部で、これら各軸部１４の基端部の周囲部分である段差面３０とを、それぞれ断面形状が部分円弧形である凹曲面３１ａにより連続させている。特に本例の自在継手を構成する十字軸１１ａの場合には、これら各凹曲面３１ａを、曲率半径が途中で変化する複合曲面としている。具体的には、これら各凹曲面３１ａのうちの前記段差面３０寄り部分である基半部３２の曲率半径ｒよりも、前記各軸部１４寄り部分である先半部３３の曲率半径Ｒを大きく（ｒ＜Ｒ）している。これら基半部３２と先半部３３とは、それぞれの一端縁同士を互いに滑らかに（互いの接線方向に）連続させると共に、前記基半部３２の他端縁を前記段差面３０と、前記先半部３３の他端縁を前記各軸部１４の外周面と、それぞれ滑らかに（それぞれの接線方向に）連続させている。   In the case of this example, the base end portion outer peripheral surface of each shaft portion 14 constituting the cross shaft 11a constituting the cross shaft type universal joint and a part of the outer surface of the coupling base portion 15 The step surface 30 which is the peripheral portion of the base end portion is continued by a concave curved surface 31a having a partial arc shape in cross section. In particular, in the case of the cross shaft 11a constituting the universal joint of the present example, each of the concave curved surfaces 31a is a compound curved surface whose curvature radius changes midway. Specifically, the curvature radius R of the front half 33 that is closer to each shaft portion 14 is set to be larger than the curvature radius r of the base half 32 that is closer to the stepped surface 30 of each concave curved surface 31a. It is large (r <R). The base half portion 32 and the front half portion 33 each have one end edge smoothly connected to each other (in a tangential direction to each other), and the other end edge of the base half portion 32 is connected to the stepped surface 30 and the step surface 30. The other end edge of the front half portion 33 is continuously connected to the outer peripheral surface of each shaft portion 14 smoothly (in each tangential direction).

上述の様な凹曲面３１ａの加工は、図２に示す様にして、前記各軸部１４の外周面及び前記段差面３０の仕上加工（内輪軌道部分の研削加工を除く）と同時に、１工程で（１度のチャッキングのみで）行う。この為に、旋削加工用のバイト３４として、前記凹曲面３１ａの断面形状に対応した（凹凸が逆で曲率半径が同じ）曲面加工部３５と、直線加工部３６とを備えたものを使用する。このうちの曲面加工部３５は、切削部の形状が、曲率半径が途中で変化する部分凸円弧状で、この凸円弧の曲率半径がこの切削部の先端側（図２の左側）よりも基端側（図２の右側）で大きくなっている。又、前記直線加工部３６は、前記曲面加工部３５の外径側端縁から径方向外方に向けて滑らかに（この曲面加工部３５の外径側端縁から接線方向に）連続したもので、形状が直線状である。本例の場合には、前記直線加工部３６を、前記各軸部１４の中心軸に対し直交する仮想平面上に位置させている。但し、後述する様に、前記段差面３０を部分円すい状の凸面又は凹面とする場合には、前記直線加工部３６を前記仮想平面に対し傾斜させる。   As shown in FIG. 2, the processing of the concave curved surface 31a as described above is performed in one step simultaneously with the finishing processing of the outer peripheral surface of each shaft portion 14 and the stepped surface 30 (excluding the grinding processing of the inner ring raceway portion). (Only with one chucking). For this purpose, as the cutting tool 34 for turning, a tool provided with a curved surface processing portion 35 corresponding to the cross-sectional shape of the concave curved surface 31a (the concavity and convexity is reversed and the curvature radius is the same) and a straight processing portion 36 is used. . Of these, the curved surface processing portion 35 has a partially convex arc shape in which the radius of curvature changes midway, and the radius of curvature of the convex arc is based on the tip side (left side in FIG. 2) of the cutting portion. It is larger on the end side (right side in FIG. 2). Further, the linearly processed portion 36 is smoothly continuous from the outer diameter side edge of the curved surface processed portion 35 outward in the radial direction (from the outer diameter side edge of the curved surface processed portion 35 tangentially). And the shape is linear. In the case of this example, the straight line processing portion 36 is positioned on a virtual plane orthogonal to the central axis of each shaft portion 14. However, as will be described later, when the stepped surface 30 is a partially conical convex surface or concave surface, the linearly processed portion 36 is inclined with respect to the virtual plane.

何れにしても、前記バイト３４により、前記各軸部１４の外周面と、前記各凹曲面３１ａと、前記段差面３０とを加工するには、前記バイト３４を前記各軸部１４に対して、それぞれこれら各軸部１４の先端側から基端側に向けて（図２の右から左に）変位させる方向に移動させる。この作業の初期段階乃至中間段階では、前記曲面加工部３５のうちの基端側部分で、前記各軸部１４の外周面を切削する。更に、前記作業の終段で、前記曲面加工部３５により前記各凹曲面３１ａを形成すると同時に、前記直線加工部３６により前記段差面３０に仕上加工を施す。従って、前記バイト３４の刃先の形状の精度さえ確保すれば、容易に、前記十字軸１１ａの外面の形状を精度良く仕上げられる。尚、ラジアル軸受１６の内輪軌道として機能する、前記各軸部１４の外周面の中間部乃至先端部には、これら各軸部１４の外周面を切削してから、前記十字軸１１ａ全体に浸炭焼き入れ等の熱処理を施した後、図示しない砥石を使用して、超仕上等の研削加工を施す。   In any case, in order to machine the outer peripheral surface of each shaft portion 14, each concave curved surface 31 a, and the step surface 30 with the cutting tool 34, the cutting tool 34 is moved with respect to each shaft part 14. These are moved in the direction of displacement from the distal end side to the proximal end side (from right to left in FIG. 2) of each of the shaft portions 14. In an initial stage to an intermediate stage of this work, an outer peripheral surface of each shaft portion 14 is cut at a proximal end portion of the curved surface processing portion 35. Further, at the final stage of the operation, each concave curved surface 31 a is formed by the curved surface processing portion 35, and at the same time, the stepped surface 30 is finished by the linear processing portion 36. Accordingly, as long as the accuracy of the shape of the cutting edge of the cutting tool 34 is ensured, the shape of the outer surface of the cross shaft 11a can be easily finished with high accuracy. Note that the outer peripheral surface of each shaft portion 14 that functions as the inner ring raceway of the radial bearing 16 is cut at the outer peripheral surface of each shaft portion 14 and then immersed in the entire cross shaft 11a. After a heat treatment such as charring, a grinding process such as super-finishing is performed using a grindstone (not shown).

上述の様にして、それぞれの基端部に前記各凹曲面３１ａを形成した、前記各軸部１４の基端寄り部分に、芯金１８と弾性材１９ａとから成るシールリング１７ａを外嵌支持する。これら各シールリング１７ａの構成は、ラジアルシールリップ２３ａの先端部が二股になっている点以外、前述の図８〜９に示した従来構造とほぼ同様である。前記各シールリング１７ａは、前記弾性材１９ａの基部２２を前記各軸部１４の基端部に締り嵌めで外嵌すると共に、前記芯金１８の円輪部２０の軸方向片側面（図１の左側面）を前記段差面３０に突き当てた状態で、前記各軸部１４の基端部に組み付けている。この状態で、前記円輪部２０の軸方向片側面と前記段差面３０とが、面同士で当接する。尚、この段差面３０のうちで前記凹曲面３１ａの周囲部分と、前記円輪部２０の軸方向片側面とは、前記各軸部１４の中心軸に対し直交する方向に存在する平坦面とする事が、各部の加工を容易にする面からは好ましい。但し、当接状態を安定させる為に、前記段差面３０と前記円輪部２０の軸方向片側面とのうちの一方を部分円すい状の凸面とし、他方を同じ角度だけ傾斜した部分円すい状の凹面とする事もできる。何れの場合でも、十字軸式の自在継手を組み立てた状態では、前記弾性材１９ａのラジアルシールリップ２３ａの先端縁が軸受カップ１３ａの端部外周面に、同じくスラストシールリップ２４が内向鍔部２５の外面に、それぞれ全周に亙って弾性的に当接する。   As described above, a seal ring 17a composed of a cored bar 18 and an elastic material 19a is externally supported at a portion near the base end of each shaft portion 14 in which each concave curved surface 31a is formed at each base end portion. To do. The structure of each seal ring 17a is substantially the same as that of the conventional structure shown in FIGS. 8 to 9 except that the tip of the radial seal lip 23a is bifurcated. Each seal ring 17a has a base portion 22 of the elastic member 19a fitted on the base end portion of each shaft portion 14 by an interference fit, and one side surface in the axial direction of the annular portion 20 of the core metal 18 (FIG. 1). Is attached to the base end portion of each shaft portion 14 with the stepped surface 30 abutted against the step surface 30. In this state, one side surface in the axial direction of the annular ring portion 20 and the step surface 30 are in contact with each other. Of the step surface 30, the peripheral portion of the concave curved surface 31 a and the one axial side surface of the annular portion 20 are flat surfaces existing in a direction perpendicular to the central axis of each shaft portion 14. It is preferable from the viewpoint of facilitating the processing of each part. However, in order to stabilize the contact state, one of the step surface 30 and one side surface in the axial direction of the annular portion 20 is a partially conical convex surface, and the other is a partially conical shape inclined by the same angle. It can also be concave. In any case, in a state where the cross shaft type universal joint is assembled, the end edge of the radial seal lip 23a of the elastic member 19a is on the outer peripheral surface of the end portion of the bearing cup 13a, and the thrust seal lip 24 is also the inward flange portion 25. Are elastically contacted with the outer surface of each of the outer circumferences over the entire circumference.

前記自在継手の伝達効率を良好にすると共に、前記各シールリング１７ａによるシール性能を確保する為には、前記各シールリップ２３ａ、２４の弾性変形量を適正に規制する必要がある。そして、この為には、前記各シールリング１７ａと前記各軸受カップ１３ａとの位置関係を適正に規制する必要がある。このうちの各シールリング１７ａの軸方向位置は、前記円輪部２０の軸方向片側面と前記段差面３０との当接により、適正に規制できる。又、前記各軸受カップ１３ａの軸方向位置は、ヨーク１０ａの円孔１２（図９参照）に対する嵌合位置を調節し、底部２８ａの内面中央部と前記各軸部１４の端面中央部とを当接させる事により規制できる。この為、本例の構造によれば、前記各シールリップ２３ａ、２４の弾性変形量を適正に規制して、前記自在継手の伝達効率を良好にすると共に、前記各シールリング１７ａによるシール性能を確保できる。   In order to improve the transmission efficiency of the universal joint and to ensure the sealing performance by the seal rings 17a, it is necessary to properly regulate the elastic deformation amounts of the seal lips 23a and 24. For this purpose, it is necessary to properly regulate the positional relationship between the seal rings 17a and the bearing cups 13a. Of these, the axial position of each seal ring 17 a can be properly regulated by the contact between the one axial side surface of the annular ring portion 20 and the step surface 30. Further, the axial position of each bearing cup 13a adjusts the fitting position with respect to the circular hole 12 (see FIG. 9) of the yoke 10a, so that the center portion of the inner surface of the bottom portion 28a and the center portion of the end surface of each shaft portion 14 are connected. It can be regulated by bringing it into contact. For this reason, according to the structure of this example, the elastic deformation amount of each seal lip 23a, 24 is appropriately regulated to improve the transmission efficiency of the universal joint, and the sealing performance by each seal ring 17a is improved. It can be secured.

更に本例の場合には、前記各軸部１４の基端部外周面と、結合基部１５の外面の一部である段差面３０とを連続させる凹曲面３１ａを、曲率半径Ｒが大きな先半部３３と、曲率半径ｒが小さな基半部３２とから構成している。この為、前記各軸部１４の長さ寸法を徒に大きくしなくても、これら各軸部１４の基端部外周面と前記段差面３０との連続部の強度を確保できる。即ち、これら各軸部１４に加わる倒れ方向のモーメントにより、これら各軸部１４と前記結合基部１５との連続部に加わる力は、前記先半部３３側で前記基半部３２側よりも大きくなる。本例の場合には、この様に大きな力が加わる先半部３３の曲率半径Ｒを大きくしているので、この先半部３３部分に生じる応力を低く抑えられる。曲率半径ｒが小さな前記基半部３２部分は、この先半部３３の周囲に設けられているので、全体としての直径が大きく、その分、前記各軸部１４の中心軸に直交する仮想平面に関する、前記基半部３２部分の断面積は、前記先半部３３部分の断面積に比較して広い。従って、当該部分に生じる応力がその分小さくて済むので、前記凹曲面３１ａ部分全体として、前記倒れ方向のモーメントに基づいて生じる応力を低く抑えられる。   Further, in the case of this example, a concave curved surface 31a that connects the outer peripheral surface of the base end portion of each shaft portion 14 and the stepped surface 30 that is a part of the outer surface of the coupling base portion 15 is formed on the first half having a large curvature radius R. It comprises a portion 33 and a base half portion 32 having a small radius of curvature r. Therefore, the strength of the continuous portion between the outer peripheral surface of the base end portion of each shaft portion 14 and the step surface 30 can be ensured without increasing the length dimension of each shaft portion 14. That is, the force applied to the continuous portion of each shaft portion 14 and the coupling base portion 15 due to the moment in the falling direction applied to each shaft portion 14 is greater on the tip half portion 33 side than on the base half portion 32 side. Become. In the case of this example, since the radius of curvature R of the front half 33 to which such a large force is applied is increased, the stress generated in the front half 33 can be kept low. The base half portion 32 portion having a small curvature radius r is provided around the tip half portion 33, and therefore has a large overall diameter, and accordingly, relates to a virtual plane orthogonal to the central axis of each shaft portion 14. The cross-sectional area of the base half portion 32 is wider than the cross-sectional area of the tip half 33 portion. Therefore, since the stress generated in the portion can be reduced by that amount, the stress generated based on the moment in the falling direction can be kept low for the entire concave curved surface 31a portion.

この為、前記自在継手によるトルク伝達時に、前記各軸部１４に加わる、倒れ方向のモーメントに拘らず、これら各軸部１４の基端部外周面と前記段差面３０との連続部に発生する応力を低く抑えられる。この結果、前記各軸部１４の長さ寸法や外径を特に大きくしなくても、大負荷時破壊強度を大きくして、前記連続部に亀裂等の損傷を発生し難くできて、前記十字軸１１ａを組み込んだ十字軸式自在継手の信頼性及び耐久性を確保できる。逆に、必要とする大負荷時破壊強度、延いては信頼性及び耐久性を同じとした場合には、前記十字軸１１ａの寸法を小さく抑えて、この十字軸１１ａを組み込んだ、十字軸式自在継手の小型・軽量化を図れる。   For this reason, at the time of torque transmission by the universal joint, regardless of the moment in the falling direction applied to each shaft portion 14, it occurs in the continuous portion between the base end portion outer peripheral surface of each shaft portion 14 and the step surface 30. Stress can be kept low. As a result, even if the length and outer diameter of each of the shaft portions 14 are not particularly increased, the breaking strength under a large load can be increased and damage such as cracks can hardly occur in the continuous portion. The reliability and durability of the cross shaft type universal joint incorporating the shaft 11a can be ensured. On the other hand, if the required breaking strength at the time of heavy load, and hence reliability and durability are the same, the cross shaft 11a is incorporated with the cross shaft 11a being kept small in size. The universal joint can be reduced in size and weight.

一方、前記倒れ方向のモーメントにより生じる応力が比較的小さくて済む、前記基半部３２の曲率半径ｒを小さくした分、前記各軸部１４の軸方向に関する、前記各凹曲面３１ａの幅寸法ｗを抑えられる。この為、前記各軸部１４の軸方向中間部乃至先端部に存在するラジアル軸受１６の為の内輪軌道の軸方向長さ、及び、前記各シールリング１７ａを構成する弾性材１９ａの基部２２を外嵌する部分の軸方向幅を確保できる。従って、前記十字軸式自在継手のトルク容量を確保すると共に、前記各シールリング１７ａの位置決め性（姿勢の安定化）も図れる。   On the other hand, the width w of each concave curved surface 31a with respect to the axial direction of each shaft portion 14 is reduced by the amount of curvature radius r of the base half portion 32 that requires a relatively small stress caused by the moment in the tilt direction. Can be suppressed. For this reason, the axial length of the inner ring raceway for the radial bearing 16 existing at the axially intermediate portion or the tip portion of each shaft portion 14 and the base portion 22 of the elastic material 19a constituting each seal ring 17a are provided. The axial width of the part to be fitted can be secured. Therefore, the torque capacity of the cross shaft type universal joint can be secured, and the positioning performance (posture stabilization) of each seal ring 17a can be achieved.

以上に述べた、本例の構造による作用・効果に就いて、図３により、更に詳しく説明する。
図３のうちの（Ｂ）の構造は、前述の図１０に示した構造に対応するもので、各軸部１４の外周面と段差面３０とを連続させる凹曲面３１の曲率半径ｒが小さい。この様な構造では、前記各軸部１４の軸方向に関するこの凹曲面３１の幅寸法ｗ０を小さくできる代わりに、前述した様に、自在継手によるトルク伝達時に、前記各軸部１４の基端部に生じる応力が大きくなり、小型・軽量化と耐久性確保との両立を図り難い。
又、図３の（Ｃ）に示した構造は、各軸部１４の外周面と段差面３０とを連続させる凹曲面３１ｂの曲率半径Ｒが大きい。この様な構造では、自在継手によるトルク伝達時に、前記各軸部１４の基端部に生じる応力を小さく抑えられる代わりに、前記凹曲面３１の幅寸法Ｗが大きくなり、この凹曲面３１の小径側端部が各軸部１４の先端側に移動する。そして、シールリング１７の基部２２（例えば図８参照）の嵌合強度を確保する為の円筒面部を確保する必要上、前記各軸部１４の全長が長くなるだけでなく、前記凹曲面３１と前記基部２２の干渉を防止しつつ、この基部２２の端面を結合基部１５の段差面３０に当接させる必要上、この基部２２も大型化する。これらにより、十字軸及びシールリングを限られた大きさのヨークに組み付ける事が難しくなり、小型・軽量化を図り難くなる。
これに対して、図３の（Ａ）に示した本例の構造は、トルク伝達時に生じる応力を低く抑えつつ、凹曲面３１ａの幅寸法ｗを、図３の（Ｃ）に示した構造よりも小さく抑えられる。この為、小型・軽量化と強度向上との両立を図る為の設計が容易になる。 The operation and effect of the structure of this example described above will be described in more detail with reference to FIG.
The structure (B) in FIG. 3 corresponds to the structure shown in FIG. 10 described above, and the curvature radius r of the concave curved surface 31 that connects the outer peripheral surface of each shaft 14 and the step surface 30 is small. . In such a structure, the instead of can reduce the width w 0 of the concave curved surface 31 in the axial direction of the shaft portions 14, as described above, when the torque transmission by the universal joint, the base end of each shank 14 The stress generated in the part increases, making it difficult to achieve both compactness, light weight and durability.
In the structure shown in FIG. 3C, the radius of curvature R of the concave curved surface 31b that connects the outer peripheral surface of each shaft portion 14 and the stepped surface 30 is large. In such a structure, at the time of torque transmission by the universal joint, the width W of the concave curved surface 31 is increased instead of suppressing the stress generated at the base end portion of each shaft portion 14, and the small diameter of the concave curved surface 31 is increased. The side end portion moves to the tip end side of each shaft portion 14. And in order to secure the cylindrical surface part for ensuring the fitting strength of the base 22 (for example, refer FIG. 8) of the seal ring 17, not only the full length of each said shaft part 14 becomes long, but the said concave curved surface 31 and While preventing the interference of the base 22, it is necessary to bring the end surface of the base 22 into contact with the stepped surface 30 of the coupling base 15, and the base 22 is also enlarged. As a result, it is difficult to assemble the cross shaft and the seal ring to a yoke of a limited size, and it is difficult to reduce the size and weight.
On the other hand, the structure of the present example shown in FIG. 3A has a lower width dimension w of the concave curved surface 31a than the structure shown in FIG. Can be kept small. For this reason, it becomes easy to design to achieve both reduction in size and weight and improvement in strength.

［実施の形態の第２例］
図４は、請求項１、３〜５に対応する、本発明の実施の形態の第２例を示している。上述した実施の形態の第１例の構造が、シール性能の高いシールリングを組み込んで成り、車室外（エンジンルーム内）に設置するのに適切な構造であるのに対して、本例の構造は、車室内に設置するのに適切な構造である。この様な本例の十字軸式自在継手の場合には、十字軸１１ａを構成する各軸部１４と各軸受カップ１３ｂとを、これら各軸部１４の軸方向に関する相対変位を可能に組み合わせている。そして、これら各軸部１４に、弾性材製のシールリングであるＯリング３７を外嵌し、これら各Ｏリング３７を、前記各軸受カップ１３ｂの開口部側端面である、この開口部に形成した内向鍔部２５の外側面と、前記十字軸１１ａを構成する段差面３０との間に挟持している。 [Second Example of Embodiment]
FIG. 4 shows a second example of an embodiment of the present invention corresponding to claims 1 and 3 to 5. The structure of the first example of the embodiment described above is a structure that incorporates a seal ring with high sealing performance and is suitable for installation outside the vehicle compartment (inside the engine room), whereas the structure of the present example. Is a structure suitable for installation in a passenger compartment. In the case of such a cruciform universal joint of this example, the shaft portions 14 and the bearing cups 13b constituting the cruciform shaft 11a are combined so as to allow relative displacement in the axial direction of the shaft portions 14. Yes. Then, an O-ring 37 that is a seal ring made of an elastic material is externally fitted to each of the shaft portions 14, and each of the O-rings 37 is formed in the opening that is an end surface on the opening side of each bearing cup 13b. It is clamped between the outer side surface of the inward flange portion 25 and the step surface 30 constituting the cross shaft 11a.

十字軸式自在継手を組み立てた状態で前記Ｏリング３７は、この段差面３０と前記内向鍔部２５の外側面との間で、軸方向に関して弾性的に圧縮する。又、前記各軸部１４の先端部と前記各軸受カップ１３ｂの内面とは離隔したままとなる。前記十字軸式自在継手によるトルク伝達時に、これら各軸部１４の先端部と各軸受カップ１３ｂとの間に作用するスラスト荷重は、前記各Ｏリング３７が支承する。尚、これら各Ｏリング３７の断面形状は、図６の（Ａ）に示した様な円形に限らず、（Ｂ）に示した様な角形でも良い。
その他の部分の構成及び作用は、上述した実施の形態の第１例と同様であるから、同等部分に関する説明は省略する。 In a state where the cross shaft type universal joint is assembled, the O-ring 37 is elastically compressed between the step surface 30 and the outer surface of the inward flange 25 in the axial direction. Further, the tip end portion of each shaft portion 14 and the inner surface of each bearing cup 13b remain separated. Each O-ring 37 supports the thrust load that acts between the tip of each shaft portion 14 and each bearing cup 13b during torque transmission by the cross shaft universal joint. The cross-sectional shape of each O-ring 37 is not limited to a circle as shown in FIG. 6A, but may be a square as shown in FIG.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, the description regarding the equivalent parts is omitted.

本発明の十字軸式自在継手は、ステアリング装置に限らず、各種トルク伝達機構に組み付けた状態で使用できる。又、各軸部の外周面と結合基部の段差面とを連続させる凹曲面を構成する、互いに曲率半径が異なる複数種類の曲面は、２種類に限らずに３種類以上であっても良い。更には、一端から他端に向けて曲率半径を連続的に変化させても良い。   The cross shaft type universal joint of the present invention is not limited to a steering device, and can be used in a state assembled to various torque transmission mechanisms. Further, the plurality of types of curved surfaces having different curvature radii that constitute the concave curved surface that connects the outer peripheral surface of each shaft portion and the stepped surface of the coupling base portion are not limited to two types, and may be three or more types. Further, the radius of curvature may be continuously changed from one end to the other end.

１ ステアリングホイール
２ ステアリングシャフト
３、３ａ、３ｂ 自在継手
４ 中間シャフト
５ ステアリングギヤユニット
６ 入力軸
７ タイロッド
８ アウタシャフト
９ インナシャフト
１０ａ、１０ｂ ヨーク
１１、１１ａ 十字軸
１２ 円孔
１３、１３ａ、１３ｂ 軸受カップ
１４ 軸部
１５ 結合基部
１６ ラジアル軸受
１７、１７ａ シールリング
１８ 芯金
１９、１９ａ 弾性材
２０ 円輪部
２１ 円筒部
２２ 基部
２３、２３ａ ラジアルシールリップ
２４ スラストシールリップ
２５ 内向鍔部
２６ 挿入孔
２７ ピン
２８、２８ａ 底部
２９ 突条
３０ 段差面
３１、３１ａ、３１ｂ 凹曲面
３２ 基半部
３３ 先半部
３４ バイト
３５ 曲面加工部
３６ 直線加工部
３７ Ｏリング DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3, 3a, 3b Universal joint 4 Intermediate shaft 5 Steering gear unit 6 Input shaft 7 Tie rod 8 Outer shaft 9 Inner shaft 10a, 10b Yoke 11, 11a Cross shaft 12 Circular hole 13, 13a, 13b Bearing cup DESCRIPTION OF SYMBOLS 14 Shaft part 15 Coupling base part 16 Radial bearing 17, 17a Seal ring 18 Core metal 19, 19a Elastic material 20 Circular ring part 21 Cylindrical part 22 Base part 23, 23a Radial seal lip 24 Thrust seal lip 25 Inward flange part 26 Insertion hole 27 Pin 28, 28a Bottom 29 Projection 30 Stepped surface 31, 31a, 31b Concave surface 32 Base half 33 Tip half 34 Bite 35 Curved surface 36 Straight line 37 O-ring

Claims (5)

それぞれが二股状に形成された１対のヨークと、これら両ヨークの両端部に互いに同心に形成された４個の円孔と、互いの開口を対向させた状態でこれら各円孔の内側に内嵌固定された、それぞれが有底円筒状である４個の軸受カップと、結合基部の外周面に４本の各軸部を放射状に固設して成り、これら各軸部をこれら各軸受カップ内に挿入した状態で前記両ヨークと組み合わされた十字軸と、これら各軸部の外周面とこれら各軸受カップの内周面との間に設けられた４組のラジアル軸受とを備えた十字軸式自在継手に於いて、前記十字軸を構成する前記各軸部の基端部外周面と前記結合基部の外面である段差面とを、それぞれ断面形状が円弧形で、曲率半径が途中で変化する凹曲面により連続させており、これら各凹曲面のうちの前記段差面寄り部分の曲率半径よりも、前記各軸部寄り部分の曲率半径を大きくした事を特徴とする十字軸式自在継手。   A pair of yokes each formed in a bifurcated shape, four circular holes formed concentrically with each other at both ends of both yokes, and inside each of these circular holes with the openings facing each other Four bearing cups that are fitted and fixed, each having a bottomed cylindrical shape, and four shafts are fixed radially on the outer peripheral surface of the coupling base, and these shafts are made into the bearings. A cross shaft combined with both yokes in a state of being inserted into the cup, and four sets of radial bearings provided between the outer peripheral surface of each shaft portion and the inner peripheral surface of each bearing cup. In the cruciform universal joint, the outer peripheral surface of the base end portion of each shaft portion constituting the cross shaft and the stepped surface which is the outer surface of the coupling base portion each have a circular cross-sectional shape and a radius of curvature. It is made continuous by a concave curved surface that changes in the middle, and the step among these concave curved surfaces Than the radius of curvature of the surface inner portion, the cross shaft type universal joint, characterized in that the large radius of curvature of each of the shaft portions close portion. 前記十字軸を構成する前記各軸部と前記各軸受カップとが、これら各軸部の軸方向に関する相対変位を実質的に抑えた状態で組み合わされており、これら各軸部の基端部にそれぞれの基部を外嵌支持された状態で、これら各軸部の基端部と前記各軸受カップの開口部との間に設けられた４個のシールリングを備え、これら各シールリングは、金属製で円環状の芯金と、この芯金を包埋する事で補強された基部及びこの基部から延出したシールリップを備えた弾性材とから成るものであり、前記各シールリングは、前記基部を前記各軸部の基端部に締り嵌めで外嵌支持すると共に、前記各シールリップを前記各軸受カップの外面に全周に亙って当接させた状態で、前記十字軸と前記両ヨークとの間に組み付けている、請求項１に記載した十字軸式自在継手。   The shaft portions constituting the cross shaft and the bearing cups are combined in a state where the relative displacement in the axial direction of the shaft portions is substantially suppressed, and the base end portions of the shaft portions are combined. In a state where the respective base portions are externally fitted and supported, four seal rings are provided between the base end portions of the respective shaft portions and the opening portions of the respective bearing cups. An annular cored bar made of an elastic material having a base reinforced by embedding the cored bar and a seal lip extending from the base, each of the seal rings is The base portion is externally supported by an interference fit to the base end portion of each shaft portion, and the cross shaft and the cross shaft are in contact with each seal lip over the entire circumference of each bearing cup. The cross shaft according to claim 1, wherein the cross shaft is assembled between the yokes. Universal joint. 前記十字軸を構成する前記各軸部と前記各軸受カップとを、これら各軸部の軸方向に関する相対変位を可能に組み合わせており、これら各軸部に、弾性材製のシールリングを外嵌し、これら各シールリングを、前記各軸受カップの開口部側端面と、前記十字軸の段差面との間で、軸方向に関して弾性的に圧縮した状態で挟持している、請求項１に記載した十字軸式自在継手。   The shaft portions constituting the cross shaft and the bearing cups are combined so as to allow relative displacement in the axial direction of the shaft portions, and a seal ring made of an elastic material is externally fitted to the shaft portions. The seal rings are sandwiched between the opening side end surfaces of the bearing cups and the stepped surfaces of the cross shafts while being elastically compressed in the axial direction. Cross shaft type universal joint. それぞれが二股状に形成された１対のヨークと、これら両ヨークの両端部に互いに同心に形成された４個の円孔と、互いの開口を対向させた状態でこれら各円孔の内側に内嵌固定された、それぞれが有底円筒状である４個の軸受カップと、結合基部の外周面に４本の各軸部を放射状に固設して成り、これら各軸部をこれら各軸受カップ内に挿入した状態で前記両ヨークと組み合わされた十字軸と、これら各軸部の外周面とこれら各軸受カップの内周面との間に設けられた４組のラジアル軸受とを備えた十字軸式自在継手を構成する前記十字軸を造る為、前記各軸部の外周面と前記結合基部の外面である段差面との連続部に旋削による仕上加工を施す際に、切削部の形状が、曲率半径が途中で変化する部分凸円弧状で、この凸円弧の曲率半径がこの切削部の先端側よりも基端側で大きくなった曲面加工部を備えたバイトを使用し、このバイトを前記各軸部に対して、それぞれこれら各軸部の先端側から基端側に向けて変位させる方向に移動させる事により、前記十字軸を構成する前記各軸部の基端部外周面と前記結合基部の外面である段差面との連続部に、それぞれ断面形状が円弧形で、前記段差面寄り部分の曲率半径よりも、前記各軸部寄り部分の曲率半径を大きい凹曲面を形成する自在継手用十字軸の製造方法。   A pair of yokes each formed in a bifurcated shape, four circular holes formed concentrically with each other at both ends of both yokes, and inside each of these circular holes with the openings facing each other Four bearing cups that are fitted and fixed, each having a bottomed cylindrical shape, and four shafts are fixed radially on the outer peripheral surface of the coupling base, and these shafts are made into the bearings. A cross shaft combined with both yokes in a state of being inserted into the cup, and four sets of radial bearings provided between the outer peripheral surface of each shaft portion and the inner peripheral surface of each bearing cup. In order to make the cross shaft constituting the cross shaft universal joint, the shape of the cutting part is applied when finishing the continuous portion of the outer peripheral surface of each shaft portion and the stepped surface which is the outer surface of the coupling base by turning. Is a partially convex arc shape whose radius of curvature changes midway, and the radius of curvature of this convex arc is Using a cutting tool having a curved surface processing portion that is larger on the base end side than the tip end side of the cutting portion, and this cutting tool is moved from the tip end side to the base end side of each shaft portion. By moving in the direction in which the cross shaft is displaced, the cross-sectional shape is an arc shape at each of the continuous portions of the outer peripheral surface of the base end portion of each shaft portion and the step surface which is the outer surface of the coupling base portion constituting the cross shaft. A method for manufacturing a cross shaft for a universal joint, in which a concave curved surface is formed in which the curvature radius of each portion near the shaft portion is larger than the curvature radius of the portion near the step surface. 前記バイトとして、先端縁に直線加工部を設けたものを使用し、前記曲面加工部により前記各凹曲面に仕上加工を施すと同時に、前記直線加工部により前記段差面に仕上加工を施す、請求項４に記載した自在継手用十字軸の製造方法。   A tool having a linearly machined portion at a tip edge is used as the bite, and the concavely curved surface is finished by the curved surface machined portion, and at the same time, the stepped surface is finished by the linearly machined portion. Item 5. A method for manufacturing a cross joint for a universal joint according to Item 4.
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JP2016038056A (en) * 2014-08-08 2016-03-22 日本精工株式会社 Rolling bearing with seal
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