A study on spring-back of pre-punched profiles in cold roll forming process

The cold roll forming is one of the common processes to form metal profiles in the industry. Due to the nature of the bending deformation in cold roll forming process, spring-back is one of the most important defects. In order to compensate the spring-back, the amount of spring-back must be correctly predicted. In this article, the effect of the hole and its position on the spring-back has been investigated by experimental and numerical methods. three channel section profiles made of St12 and thickness of 1 mm, without hole, with circular holes on the bend area and with holes on the flange were used. Cold roll forming was done in three stations with a fixed bending radius pattern with 15 degree bending in each forming station and numerical solution using Abaqus finite element software. The results indicate that there is a relationship between the amount of spring-back and the position of the hole in such a way that the amount of spring-back in hole on the bend area profile is 9% more than the hole-less profile and in hole on the flange profile is 16% less than hole-less profile. Also, according to finite elements results, it was observed that the amount of equivalent strain in the bend area of the profile with holes on the bend area is 20% less and in the profile with holes near the bend area is 16% more than the profile without holes, which can justify the difference observed in the amount of spring-back.