| 摘要 |
PROBLEM TO BE SOLVED: To uniformly perform electrolytic etching for the whole surface of a face to be electrolytic-etched by varying an electric current flowing between a work and an electrode with the passage of the time. SOLUTION: A cylinder bore is subjected to honing (honing is not electrochemical processing), and subsequently the honed cylinder bore surface is subjected to electrochemical processing in which an electric current flowing between an electrode 1 inserted in the cylinder bore and the cylinder bore surface varies with the passage of time to roughen the cylinder bore surface (more rough than the honing machined surface) to form a surface having favorable oil retaining performance. At this time, first, a smaller current is carried, whereby a region where a current is easily to concentrate is first subjected to electrolytic etching so that the region where a current is easy to concentrate is eliminated. Thus, the whole surface of a fact to be electrolytic-etching can be uniformly electrolytic-etched.
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