| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of forming a bearing bush fixed to the inner face of a boss portion of sheet metal parts, for eliminating the need for high- precision working and reducing manufacturing cost. SOLUTION: A bearing bush material 18A having a flange portion 18a formed at one end is inserted at the other end into the inner face of the cylindrical boss portion 12 integrally formed on the sheet metal parts 10 with an inner face widely opened portion 12b at one end, and the boss portion is supported in a retaining hole 30a of a die 30. The bearing bush material, in which a push-in portion 35a at the end of a punch 35, is pushed at its opposite side to the flange portion is plastically deformed, so that its thickness is reduced, and its inner and outer diameters are increased and attached closely to the inner face of the boss portion; the bearing bush material is attached closely at its opposite side to the flange portion to the inner face wide opened portion of the boss portion by a punch wide opened portion 35b at the root of the push-in portion. A knock-on pin 31 in contact with the flange portion is provided in the retaining hole for supporting working thrust on the bearing bush material.
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