Joints and connections – Articulated members – Pivoted
Reexamination Certificate
1999-06-02
2001-05-22
Browne, Lynne H. (Department: 3629)
Joints and connections
Articulated members
Pivoted
Reexamination Certificate
active
06234704
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a ball stud having a buckle portion adapted to buckle under an external stress. The present invention also relates to a method and an apparatus for producing the ball stud. The present invention further relates to a ball joint including such a ball stud.
Conventional methods of producing a ball stud, including a buckle portion adapted to buckle under an external stress, are disclosed in Japanese Patent Laid-open No. 1994-55237.
The ball stud production method disclosed in Japanese Patent Laid-open No. 1994-55237 produces a ball stud of a ball joint which is used as a steering mechanism in a steering system of an automobile. The conventional production method forms a buckle portion by swaging or rolling the portion of a bar-shaped material intended for buckling. The resulting buckle portion of the bar-shaped material is reduced in diameter by a predetermined percentage. The material to be processed is formed into a bar beforehand by cold forging.
The ball stud production method disclosed in Japanese Patent Laid-open No. 1994-55237 requires a heavy load to squeeze the bar-shaped material to form a buckle portion having an axial length sufficient for buckling. Since the buckle portion is formed by merely squeezing the rolling bar-shaped material, a heavy load is necessary. Such a heavy load not only requires a large processing machine, but also reduces the life span of the roller or processing jigs, requiring the frequent replacement of these jigs. The problems associated with the conventional method of ball stud production make the manufacture of the ball stud difficult, which consequently increases the production costs.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a ball stud production method which overcomes the foregoing problems.
It is a further object of the present invention to provide a ball stud production apparatus which overcomes the foregoing problems.
It is still a further object of the present invention to provide a ball stud having an easily formed buckle portion.
Briefly stated, the present invention provides a ball stud having a buckle portion designed to buckle under an appropriate amount of longitudinal pressure. The buckle portion is formed by a rolling process resulting in furrowed portions and raised portions integrally formed in an accordion shape along a portion of the ball stud. The raised portions are formed from the surplus material displaced from forming the furrowed portions. The buckling strength is variable depending on the number of furrowed portions and raised portions in the ball stud. A ball bead, connected to the ball stud is inserted into an opening of a housing. The process of making the ball stud requires minimal pressure in the rolling process, resulting in reduced production costs and roller wear.
According to an embodiment of the present invention, there is provided a ball stud comprising a ball head portion, a stud portion, the ball head portion integrally formed on one end of the stud portion, a buckle portion included in at least a portion of the stud portion, the buckle portion buckling under an appropriate amount of external longitudinal stress, the buckle portion having alternately arranged furrowed portions and raised portions extending in an axial direction along the portion, the furrowed portions having minimum diameters that are smaller than a remainder of the stud portion, the raised portions having maximum diameters that are larger than a remainder of the stud portion by displacement of material from the furrowed portions, and a number of the furrowed portions and the raised portions being effective to provide a desired buckling strength.
According to another embodiment of the present invention, there is provided a ball joint comprising a ball head portion, a stud portion having the ball head portion integrally formed at one thereof, a buckle portion in a portion of the stud portion, the buckle portion having a strength effective to permit buckling under an appropriate amount of external longitudinal stress, the buckle portion having alternately arranged furrowed portions and raised portions extending in an axial direction along the portion, the furrowed portions having minimum diameters that are smaller than a remainder of the stud portion, the raised portions having maximum diameters that are larger than a remainder of the stud portion by displacement of material from the furrowed portions, a number of the furrowed portions and the raised portions being effective to provide a desired buckling strength, a housing having an inner chamber, the inner chamber having an opening at one end thereof, and the ball head portion slidably movable in the inner chamber.
According to a further embodiment of the present invention, there is provided a method of making a ball stud having a ball head portion integrally formed on one end of a stud portion comprising rolling a portion of the stud portion to form a buckle portion, the buckle portion having alternately arranged furrowed portions and raised portions extending in an axial direction along the portion, and the furrowed portions having minimum diameters that are smaller than a remainder of the stud portion, the raised portions having maximum diameters that are larger than a remainder of the stud portion by displacement of material from the furrowed portions, and a number of the furrowed portions and the raised portions being effective to provide a desired buckling strength.
According to another embodiment of the present invention, there is provided an apparatus for producing a ball stud having a ball head portion and a stud portion comprising at least first and second buckle forming members each having an outer surface adapted to contact an outer surface of the stud portion, the outer surface having furrow-forming portions and groove-shaped material-raising portions, and the furrow-forming portions and the material-raising portions alternately arranged to form an accordion shape.
The above, and other objects, feature and advantages of the present invention will become apparent from the following description read in conjunction with accompanying drawings, in which like reference numerals designate the same element.
REFERENCES:
patent: 135771 (1873-02-01), Burtch
patent: 2832223 (1958-04-01), Cauraud
patent: 2884250 (1959-04-01), Patterson
patent: 4755078 (1988-07-01), Blumberg et al.
patent: 5704726 (1998-01-01), Nemoto
patent: 5752780 (1998-05-01), Dorr
Oda Takahiro
Sukigara Tadamasa
Browne Lynne H.
Cottingham John R.
Kabushiki Kaisha Somic Ishikawa
Morrison Law Firm
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