An upper bound analysis for reshaping thick tubes to polygonal cross-section tubes through multistage roll forming process

• A 3D upper bound solution for roll forming of polygonal tubes is presented.
• The simulation can be generalized for arbitrary number of stages and section sides.
• Height, thickness, outer corner of the cross-section at any pass can be calculated.
• The modeling and simulation can be used in pipe industry.

In this investigation, an upper bound solution is presented for the multistage forming process to produce polygonal cross-section thick tubes by means of a roll forming rig with flat rolls. The modeling and simulation is presented so that it can be generalized for arbitrary number of sides and stages.Comparison of theoretical and experimental results for tube cross-section dimensions (height, wall thickness and outer corner radius) show good agreement for a square section tube and demonstrated the capabilities of the new formulation presented.