Metal deforming – By use of closed-die and coacting work-forcer – Forcing work into or within closed die; e.g. – forging
Patent
1996-03-14
1997-12-16
Larson, Lowell A.
Metal deforming
By use of closed-die and coacting work-forcer
Forcing work into or within closed die; e.g., forging
72359, 723536, B21D 2200
Patent
active
056972458
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates in general to an apparatus and method for forge-forming an outer-ring of a constant velocity joint, and more particularly to an apparatus for forge-forming the outer-ring of constant velocity joint capable of producing a high precision outer-ring by only a contraction of punch pieces instead of expansion and contraction, and of preventing breakage of the punch pieces by simplifying the structure of an outer-ring forging punch and a lower press, and a method thereof.
BACKGROUND ART
The constant velocity joint has dual shafts in which and inner-ring 1 and outer-ring 2 formed at its end are connected through a torque transmitting ball 3 inserted into ball grooves 5 and 6 which are formed uniformly between the inner-ring and outer-ring as shown in FIGS. 1 and 2.
A peripheral surface 7 of the inner-ring 1, an inner surface 8 of the outer-ring 2, and a ball cage 4 are formed of a spherical surface in which its center of curvature is located at the center of joint 0, and the ball groove 5 of the inner-ring 1 and the ball grove 6 of the outer-ring 2 are formed of curves which have the center of curvature on offset points A and B aparted equal distance from the center of joint 0. Therefore, since a track of ball center travelling the ball groove has the curve with the center of curvature at points A and B, the ball 3 is always directed to a plane bisecting an angle which dual shafts form, thereby maintaining the constant velocity.
To fabricate such an outer-ring of the constant velocity joint in which has the inner surface of the spherical surface and the ball groove of the curved surface, the prior art method forms the inner surface and the ball groove by cut-forming an outer-ring forming material in which both the inner surface and the ball groove are hot forged as straight.
However, since the centers of curvature of the spherical inner surface 8 and the ball groove 6 are equal each other and there shapes are complicated, it takes long time in fabricating it by milling and wastes many portions of the forming material.
Recently, many fabricating apparatuses for the constant velocity joint have been developed and used. For example, Japanese Laid-open Patent Gazette No. 57-177843 discloses a method of fabricating the outer-ring of the constant velocity joint. This method prepares a pre-formed material in which the inner surface is formed as conical shape which expands from maximum diameter portion to apature end, the ball grooves are formed on the inner surface as straight from maximum diameter portion to apature end, and small escaping grooves are formed on the spherical surface between ball grooves.
Then, the inner surface of the material is contracted from the periphery to diameter direction on a die having a conical inner surface, by using seperate type punch which plural curve forming members are mounted contractably and a protruding punch, in the state that gap between curve forming members are located in line with the escaping grooves of the material.
The above-mentioned technique has problems which are apt to break punch pieces and a punch piece guiding shaft due to vertical load in mass production and are difficult to replace the broken punch pieces for new punch pieces. Further, since the punch pieces are coupled to the punch piece guiding shaft with gap, undersirable protrusion portions are formed in the spherical inner surface of the inner-ring after forge forming.
Since the punch pieces may be shifted right and left, the precise bisect angle of ball track grooves and the distance therebetween can not be guaranteed in the formed outer-ring.
To solve such problems of the above technique, another outer-ring forging apparatus and method have been proposed at Korean Patent Gazette No. 91-3896. This technique forms spherical inner suface and ball track grooves by forging a material in which semicircled track grooves and circular surface are formed previously.
However, according to this technique, the outer-ring is fabricated by pressing, expansion and contract
REFERENCES:
patent: 4406146 (1983-09-01), Suzuki
patent: 5001920 (1991-03-01), Ishinaga et al.
patent: 5099672 (1992-03-01), Steinhauser et al.
Butler Rodney A.
Larson Lowell A.
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