Patent ID: 7188501
Filing Date: 2007-03-13
Classification: B21B

Abstract:
1. A cold rolling process for metal tubes in which the cold rolling process by pilger rolling that employs a pair of roll-dies with a roll caliber comprising a roll caliber diameter Dx and a side relief amount Fx and holds a mandrel between each of said roll-dies is applied as a final finishing process: wherein a side relief rate SR of said roll-dies expressed by the equation [1] as below is set in the range of 0.5 to 1.5%; wherein said mandrel is configured in such a way that a taper θ wherein a feed rate F (per one pass) of a workpiece material is set in the range of 1.0 to 2.5 mm, the relationship between the side relief SR and the feed rate F expressed by the equation [2] as below being satisfied: