MANUFACTURING METHOD FOR BUSHING AND SUSPENSION ARM

PROBLEM TO BE SOLVED: To provide a manufacturing method for a bushing which can suppress occurrence of crack of a coating film formed on an external cylinder even when increasing a restricting quantity of the external cylinder.SOLUTION: A manufacturing method for a bushing 1 which is formed by vulcanization-adhering an external cylinder 3, formed in a cross section C-shape comprising slits 7 and subjected to chemical conversion coating-film processing, to an internal cylinder 2, with a rubber elastic body 4, includes: a restricting step of restricting a distance between the slits 7 of the external cylinder 3 to narrow the distance; a chemical conversion coating-film processing step of subjecting the external cylinder 3 to chemical conversion coating-film processing while keeping the restriction by the restricting step; and an elastic body adhering step of vulcanization-adhering the external cylinder 3 to the internal cylinder 2 with the rubber elastic body 4, in a state where the distance between the slits 7 becomes larger than the distance between the slits 7 during the restricting step.SELECTED DRAWING: Figure 3 【課題】本発明は、外筒の絞り量を大きくしても外筒に形成した皮膜の割れの発生を抑制することができるブッシュの製造方法を提供する。【解決手段】スリット７を備えた断面Ｃ字形状であり化成皮膜処理された外筒３と、内筒２とがゴム弾性体４で加硫接着されることにより形成されるブッシュ１の製造方法であって、前記外筒３のスリット７間の距離が近づくように絞る絞り工程と、前記絞り工程による絞りを維持した状態で前記外筒３に化成皮膜処理を行う化成皮膜処理工程と、前記絞り工程時のスリット７間の距離よりもスリット７間が広がった状態で前記外筒３と前記内筒２とを前記弾性体４で加硫接着する弾性体接着工程と、を有することを特徴とする。【選択図】図３