Comparison of Bending of Automotive Steels in Roll Forming and in a V-Die

Abstract

Bending in a V-die has been used to indicate the outcome of bending in cold roll forming, although little direct correlation has been performed. In this work direct comparison of the springback in both processes was performed using six samples of automotive steels in a conventional roll forming line where the transverse springback is measured. A bend of similar radius was formed in a V-die and the springback determined. In general, the springback in V-die forming was greater than in roll forming, in some cases by a factor of 2. The theoretical springback angle was determined for all steels using a simple and approximate analytical equation and compared to the experimental roll forming and bending results. While for the roll forming process good agreement was achieved the theoretical values significantly underestimated springback in the V-bending process.

Experimental study into the correlation between the incremental forming and the nature of springback in automotive steels

“…In their study, a V-section was formed using a five-station roll forming process and by single step V-bending. They observed higher springback in single step bending compared to roll forming (Weiss et al, 2012).…”

“…Six types of automotive steel having thicknesses in the range of 1.6 to 2.0 mm were tested; the thickness and yield strength levels of all steels are given in Table 1. The chemical composition of above steels is given in Weiss et al (2012). A 100 kN Instron was used to carry out the tensile tests according to the Australian standard AS 1391-1991.…”

A Study of Cold Roll Forming Technology and Peak Strain Behavior of Asymmetric Corrugated Channels

“…Correspondingly, the number of rolls and bending angle each of sets can be determined by Eqs. (1) and (2), which are derived by Ona et al [7] through comparing the relationship between the shape factor and molding passes, see Table 2.…”

A numerical study on chain-die forming of the AHSS U-channel and contrast with roll forming

“…The tool design of chain-die forming is straightforward, as it likes a -rotational stamping‖. On the contrary, a roll forming process needs deliberate forming flower pattern design and roll design [6]. Two roll forming schemes for the U-channel with different bending angle increment, 30° and 15° respectively were modeled (denoted by roll forming-30° and roll forming-15° respectively), as shown in Fig.…”

“…In recent decade, roll forming has been drawn much attention in manufacturing AHSS structural and crash parts, like bumper beam [3], side impact door beam [4], associated brackets, seat structures, fascia supports etc., due to several pronounced advantages for bending over deep drawing/bending process, such as less tool wear, tighter bend radius, lower level of springback [5,6], etc., which are mainly attributed to its nature of incremental forming [7]. Besides, springback and shape defects can be flexibly compensated by appropriate adjustment of roll positions [8].…”