Investigating the effect of different parameters on the occurrence of collapse defect in re-shape rolling of circular pipe into a square tube

In recent years, various ways have been used for productions of square tube by reshaping processes. Mainly, it is expected that forming of a square tube that does not have any defects for using in industrial application, should be investigated during the design stage, before trials begin. In this paper, the elasto-plastic deformation of a circular pipe into a square tube without any defects, during the cold re-shape rolling process, is examined by Abaqus finite element software. The occurrence of collapse defect (parameter C) in the flat part of square tube during the forming process is one of the influential negative factors in the final quality of these tubes. Accordingly, the effects of various process parameters such as geometric ratio, roll gap reduction, friction coefficient, roll radius and the material of the pipe, on the occurrence of collapse defect in the squaring process are discussed. The findings show that with increasing the roll gap reduction, the amount of parameter C increases for constant geometric ratios. The geometric ratio is a major factor on the occurrence of collapse defect in the process of squaring circular tubes. In order to verify the simulation results, several experimental tests were performed. Obtained results of simulation showed good agreements with the experiment results.