The origin of end flare in roll formed profiles

Abstract

Roll forming is a continuous manufacturing process designed for large batch sizes. In order to economically produce roll formed parts with smaller batch sizes, the process setup times have to be reduced. During the setup, profile defects and especially the deformation caused by the release of the process-inherent residual stresses, also known as end flare, have to be counteracted. However, the knowledge regarding the creation of residual stresses is limited and the ability to reduce end flare usually depends on the experience of the process designer and the machine operator, which makes the setup time-consuming and cost-intensive. Therefore, in this paper the creation of end flare during the roll forming process is investigated in depth. As a result of this study explanation models for U-, C- and Hat-profiles, which link the creation of residual stresses to the local deformation during the forming process, are developed. Knowing how changes in the forming curve affect the creation of end flare allows to use a knowledge-based approach during the design and setup process, thereby reducing time and costs.

The precise control of end flare with residual stresses of UHSS thin-walled component in roll forming process

“…X a is width of stationary zone, X b is width of front end and X c is width of back end. Then, end flare can be calculated as Equation (5).…”

“…During RF process of hat-section, first, the strip is contacted with the bottom roll and the side of the strip (vertical wall and flange) is lifted up and formed with the concave curve; then, top roll will contact with the strip, flange will be bent downwards along the curve of top roll, in an opposite direction with vertical wall. The forming curve is from the concave curve to convex curve [5]. The longitudinal bending stress is changed at the contact line before entering the roll gap.…”

“…However, When the roll-formed components are cut, the residual stresses of strip will be released. Deformation will occur near the cut ends, which is called end flare, and it will result in inconsistencies between the two cut sections to increase the difficulty in installing [5]. It’s necessary to adopt additional operations to compensate for end flare, which will increase the manufacturing cost and waste production time [6].…”

Application of Mean Modulus in Three-Point Bending and Roll Forming

“…Bending parts account for a large proportion of mechanical parts, and springback is the key factor affecting the quality of them. The springback problem of materials generally exists in roll forming [ 1 , 2 ], stamping [ 3 , 4 ], bending [ 5 , 6 ] and other processes. Relative bending radius, bending angle and bending mode are the main factors affecting material springback.…”

Optimization design of process parameters for cold and hot composite roll forming of the AHSS square tube using response surface methodology

“…To improve the quality of AHSS products, many scholars have focused on the forming mechanism of defects and the optimization of process parameters. Moneke et al [15] investigated the creation of end flare during the CRF and presented a countermeasure to reduce end flare by adopting the roll gap [16]. Cheng et al [17] developed the UDT (USTB-Durable T) -type angle adjusting method to compensate springback with the improvement of the edge waves and asymmetric behavior.…”