| 摘要 |
PURPOSE:To obtain stronger adhesion of a nickel-fluorine composite plating layer by providing deeper etching to such parts as the minor axial side of the inner periphery of a housing and the perimeter of its opening than other parts, when etching by reverse electrolysis is provided to a hard plating layer formed on the inner periphery of the housing. CONSTITUTION:A rotor housing 20 is formed of a seat insert process 12, i.e., a cylinder of steel plate, moulded into a rotor housing body 21, with its inner peripheral surface 23 shaped trochoidal, and the inner peripheral surface 23 provided with a hard plating layer 25. Further, etching by the 1st reverse elec trolysis is provided to the hard plating layer 25, and in this case, the depth of porosity obtained by etching a minor axial side and the perimeter of an opening 24 is made deeper than that of other parts. Then, the surface of the hard plating layer 25 is provided with honing work and machined in a convex shape axially, etching is provided thereto by the 2nd reverse electrolysis, and finally the formation of a nickel-fluorine composite plating layer 28 is provided.
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