Cold rolling process for metal tubes

摘要

In the cold rolling process by pilger rolling that holds a mandrel between each of paired roll-dies, by optimizing the side relief rate SR and the pass schedule factors such as the Area Rd, ID Rd and the feed rate F of the workpiece material, and further by properly selecting the taper θ1 in the primary deformation zone of mandrel and the taper θ2 in the final size reduction zone thereof, the dimension-related shape characteristics (near-perfect round shape) of the tube inside surface after the final finishing rolling process by pilger rolling can be ascertained to thereby ensure excellent surface property without requiring a new apparatus, and further without causing the decrease of the product yield and/or the increase of the manufacturing costs. Thus, this can be widely applied for producing steam generator tubes which exhibits high S/N ratio in the inner coil eddy current testing.