Experimental investigation of the ovality of holes on pre-notched channel products in the cold roll forming process

Owing to the increasing use and demand of pre-notched sections in automotive and construction industries, cold roll forming is a suitable production process because of its high efficiency. However, some defects such as ovality in the holes might reduce the quality of the products. In this study, the conversion of pre-notched strips into channel section products was investigated experimentally during a cold roll forming process. The effects of a number of features such as the flower pattern (the forming angle increment), uphill and downhill strategies, the horizontal distance between the stands, the lubrication condition, the longitudinal distance between the holes, the distance between the holes and the product edge, the hole diameter, the width of the channel web and flange, and the strip thickness on the ovality are discussed. The results showed that the forming angle increment has the most significant influence on the hole ovality, whereas the web width and lubrication condition are of the least importance. Furthermore, comparing the results of the forming of the pre-notched strips with those of strips without holes showed that piercing the holes intensifies hole ovality.