| 摘要 |
A method of making a ball stud from a metal rod, comprising the steps of cutting from the metal rod, a blank having generally the same volume and outer diameter as that of a finished ball stud, forwardly extruding one end of the blank positioned within a die cavity to form a taper, stem and shank portions, forming a preliminary cylindrical shape with a shallow cavity on the other end of the blank, the diameter of said preliminary cylindrical portion being smaller than the outer diameter of a finished spherical head, backwardly extruding the other end to form a preliminary cylindrical shape having a wall of generally the same thickness as that of a finished spherical head portion, and upsetting the preliminary cylindrical shape to form a spherical hollow head portion in the die cavity, whereby the upsetting operation is achieved with an application of a mixture of oil and air to pressurize the inner space of the spherical hollow head portion.
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