| 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 theta 1 in the primary deformation zone of mandrel and the taper theta 2 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.
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