| 摘要 |
PURPOSE:To produce a thick steel plate having different sizes in width with good yield by repeating the rolling wherein a rolling material is formed with thin-walled recesses and is rolled after the material is rotated 90 deg.. CONSTITUTION:After a heated slab 11 is subjected to 2-3 passes of forming by rolling in its longitudinal direction, thin-walled recesses 13 are formed in the prescribed positions in the intermediate part of the rolling material by exertion of strong screwing-down thereupon. The resultant rolling member 12 is rotated 90 deg. and is subjected to broadside rolling. Since the recesses 13 are thin-walled, the broadside spreading is smaller as compared to the thick-walled parts, and a rolling material 14 formed with constricted parts 15 on both sides is obtained. Such material 14 is rotated 90 deg. and is subjected to forming pass rolling. With the parts 15 as a boundary, the rolling reduction is changed and a rolling material 16 having wall thicknesses changing in the rolling direction is formed in said rolling. In succession the material 16 is rotated 90 deg. and is subjected to broadside rolling and the resultant material 17 is further rotated 90 deg. and is subjected to finish rolling down to a finish thickness, whereby a dissimilar width steel plate 18 having sharp stepped parts 19 is formed. |
