Influence of coined-bead die on spring-back characteristics in V-die bending process using the finite element method

Abstract

The coined-bead technique is an effective approach for controlling the spring-back characteristics involved in sheet-metal bending. Most previous studies have focused on the application of the coined-bead punch. In this application, bead marks are commonly formed on the inner radii of the bent components. To ensure the precision of the inner bent radius, a coined-bead die can be employed. However, information and data pertaining to coined-bead die applications are currently lacking. In the present research, the influences of the coined-bead die on the spring-back characteristics during V-die bending are investigated for aluminium alloy sheets (AA1100-O), by using the finite element method (FEM) and related physical experiments. Based on material flow and stress distribution analyses, it is found that the bending mechanism of coined-bead die application (particularly in the coining stage) is different from that of coined-bead punch application. Moreover, an increase in the punch radius-to-workpiece thickness ratio and decreases in the bend angle and coined-bead width result in increased spring-back characteristics. It is revealed that the coined-bead die can be applied to prevent spring-back characteristics and the bead mark at the inner radius. However, it was also noted that the V-shape parameters should be carefully considered for coined-bead applications. In addition, it is recommended that the width of the coined-bead die should be larger than that of the coined-bead punch.

Three-point bending straightening algorithm and verification for I-type seamless welded rail

“…The C S À x relationship in three stages of vertical loading (equations ( 15), (17), and ( 19)) can be expressed as:…”

“…Elastoplastic mechanics and ideal elastic-plastic material model 16 were also adopted to establish the relationship between the initial deflection of the round bar and the straightening stroke. Thipprakmas and Sontamino 17 investigated the influences of the coined-bead die on the spring-back characteristics during V-die bending for aluminum alloy sheets (AA1100-O) by using the finite element method and related physical experiments. Gao et al 18 investigated the spring-back behaviors of the AA6082 aluminum profiles based on the flexible multi-points 3D stretch-bending process to achieve high-efficiency and high-quality forming of such kind of structural components.…”

Effects of the material properties and thickness on the minimum formable radius in the subtle feature forming process

“…Wanintradul et al [12] developed a new experimental method to investigate the occurrence of skid lines during the stamping process. Thipprakmas and Sontamino [13] studied the effects of a coined-bead die on the spring-back characteristics during V-die bending. However, it is di cult to nd research on the geometric accuracy of features, such as the radius of curvature of feature lines.…”