| 摘要 |
PROBLEM TO BE SOLVED: To produce a phosphor bronze alloy flat square wire for an extremely thin and narrow straight spring high in straightness by forming electrolytic plating film of tin, solder or copper on the outer circumferential face of a phosphor bronze alloy flat square wire. SOLUTION: A phosphor bronze alloy material in which the average content of tin is regulated to 7 to 9wt.% is subjected to drawing to form into a phosphor bronze alloy round wire having required wire diameter. Next, this drawn round wire is subjected to rolling to form into a phosphor bronze alloy flat square wire having <=80μm thickness and <=140μm width. Then, this flat square wire is subjected to straightening treatment while tension is applied thereto in a heating furnace to form into a phosphor bronze alloy flat square spring wire. Successively, this phosphor bronze alloy flat square spring wire is subjected to electrolytic degreasing, and after that, tin film, solder film or copper film is formed on the outer circumference by electrolytic plating. In this way, the extremely thin and nallow flat square wire having >=1000mm straightness whose production has been difficult heretofore, and in which the thickness of the plating is uniform and the plating surface is smooth can be obtd.
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