| 摘要 |
PURPOSE:To simplify coupling of an inner cylinder to an outer cylinder and to enhance certainty by preparing a punch expanded to an outer periphery, engaging the inner cylinder in which a release stopper protrudes with an outer periphery of one end of the punch, engaging the punch within the outer cylinder, press injecting the outer cylinder in a recess of a die, and ironing a part except the punch with the inner cylinder via an expanded part. CONSTITUTION:An inner cylinder 43 of a double cylinder is formed of a ferromagnetic material of iron, etc., formed in a cylinder having a smaller diameter than that of an outer cylinder 41 formed of aluminum hot forging, and a height of an expanded part 34 of a punch 33 is set corresponding to a size of a gap 44. A release stopper 45 protrude integrally in a substantially circular ring shape at is outer periphery, is mounted on an outer periphery of the punch 33. When the stopper 45 is press injected in a recess 32 of a die 31 in a state engaged with a predetermined position in a hollow part 42 of the cylinder 41, it is forcibly brought into pressure contact with the outer periphery of the cylinder 43. Further, a material of an end side at both sides of the gap 44 of the cylinder 43 is expanded to be deformed to a step 46 side by ironing to form an engaging part to be engaged radially from outside of the step 48. |
