| 摘要 |
A cold roll forming method for reducing the diameter of a metal pipe and a metal pipe product having the diameter reduced by such method are disclosed, wherein the method includes the steps of passing a raw metal pipe through a set of pre-forming rolls so that it can be pre-formed into an intermediate metal pipe having an elliptic, elongated circular or rectangular cross-sectional shape and then passing the intermediate metal pipe through a set of diameter-reducing rolls disposed on the downstream side of the set of pre-forming rolls so that it can have its outer circumferential length reduced to a smaller length than the outer peripheral length of the raw metal pipe while at the same time it can be re-formed into the circular cross-sectional shape or any other cross-sectional shape different from the cross-sectional shape of the intermediate metal pipe. <IMAGE>
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