| 摘要 |
PURPOSE:To prevent a rubber layer from defoliation by forming one of the ends of a shell with a larger diameter than that of the ball of a ball stud, jointing an expansion head to the inner wall of the steel through a rubber layer, and deforming the both ends of the shell into ball form by pressure. CONSTITUTION:A core shaft 3 having a head part 4 is formed in advance by cold plastic process. The thickness of the shell 6 is selected to a small value to increase the thickness of a rubber layer 5, and the radius of curvature R3 of an end part 9 situated at the foremost part of the head of said core shaft 3 is given a considerably larger value than the radius R2 of ball-shaped shell 7 after pressure forming for spherical surfaces. The shell 6 and head 4 are set in a die, and rubber is injected in the space between these mating members, followed by vulcanizing burn-in process, to form a ball stud 2. Then the both ends 8, 9 of the shell 6 are deformed by cup dice 20, 21, etc. for pressure forming. Thereby the two ends of rubber layer 5 viewed in the axial direction are compressed to provide the rubber layer 5 with a sufficient compression stress for prevention of defoliation. |
