Abstract
Ultra heavy gauge steel square tubes have been required as columns to promote the beautiful design of such as glass-faced buildings and shopping arcades. There have been some methods of manufacturing square columns, but manufacturing heavy gauge tubes was difficult in either method. Then hot forming was suggested as a method of manufacturing heavy gauge tubes by reshaping round cross-sectional mother pipe into square shape. Sharpness of the corners and flatness of the sides are both essentially required. Rigid plastic finite elemental method was applied to simulate the deformation of the material during the hot forming, and influence of forming condition on the both requirements was discussed. 2-roll-type hot sizing mill was applied as the instrument of the hot forming. The simulations were carried out in 4 cases with difference of total reduction or distribution of reduction at each stand. The square tube was experimentally formed under one of the above 4 cases.
The calculated result was in a good accordance with the experimental result. The shapes of corners become sharper as growth of the total reduction. The sides become flatter as the reduction at the final stand is smaller. Large total reduction with small reduction at the final stand is recommendable to satisfy the both of sharp corners and flat sides.
