ROLLING METHOD OF ROUGH SHAPE BILLET FOR Z SHAPE

摘要

PURPOSE:To roll a rough shape billet for a Z shape having less cracks in pawl parts with high efficiency and high yield by rolling down a slab by roll calibers to a billet of a dog bone shape having a spread in both end parts then rolling the billet with forming calibers. CONSTITUTION:A continuously cast slab is erected in a transverse direction and is rolled to a dogbone shape by using calibers 20-4 with projections of roll calibers and the grooves for promoting a leg length E are provided by projections 20-4a. The slab is then subjected to rolling for removing the grooves with rectangular calibers 20-1 to cause metallic flow in an arrow F direction. The material is rotated 90 deg. and is formed with dog bone calibers 20-5 to an intermediate billet 24 having a prescribed dog bone type sectional shape with less pulldown P in the stage of form rolling. Such billet 24 is subjected to form rolling with the 1st forming calibers 20-2 then to form rolling with the 2nd forming calibers 20-3 having the caliber shape corresponding to the intended sectional shape, whereby a rough shape billet 14 for a Z shape is obtd.