Development of anew spring-back factor for a wiping die bending process

Spring-back factor applied for V-bending die design

“…However, as the key factor for the spring-back prediction and bend radius calculation, the spring-back factor has not been thoroughly investigated, especially for the V-die bending process. Only a few research studies on this issue have been conducted (Ling et al, 2005), (Phanitwong and Thipprakmas, 2016), (Ling et al, 2005) confirmed the results, which corresponded well with the conventional spring-back factor (Lang, 1985) in that the decreases in the spring-back factor were obtained as the ratios of the die radius to the part thickness and the part radius to the part thickness increased. (Phanitwong and Thipprakmas, 2016) developed a new spring-back factor, named the adjusted spring-back factor, for a wiping die or L-die bending process.…”

“…These cause the main barrier to control the dimensions of bent parts to meet their requirements. In general, the spring-back factor has come a long way to apply for spring-back prediction and bend radius calculation (Lang, 1985), (Sculer, 1998), (Ling et al, 2005), (Phanitwong and Thipprakmas, 2016). In terms of V-die bending process, the spring-back factor is commonly defined as the ratio of the bend angle of the tool to the bend angle of workpiece after unloading as shown in Equation (1).…”

“…However, in the recent years, the spring-back factor has been investigated and developed to achieve more accuracy of spring-back prediction and bend radius calculation (Ling et al, 2005), (Phanitwong and Thipprakmas, 2016). The new finding revealed in (Phanitwong and Thipprakmas, 2016) is that, in L-die bending process, not only the pure bending characteristics are generated in the bending allowance zone and reversed bending characteristics are also generated in the unclamped leg. These generated stress characteristics are considered for an adjusted spring-back factor.…”

Design of U-Geometry Parameters Using Statistical Analysis Techniques in the U-Bending Process

“…The U-bending process is typically subdivided into two types of U-die-bending: with and without pressure pads [19]. Diagrams of the U-bending models investigated in the present study, with and without pressure pads, are shown in Figure 1.…”

“…The other material properties are given in Table 1, where E, σ u and ν denote, respectively, the Young modulus, ultimate tensile stress, and the Poisson's ratio. To define the accuracy of the friction coefficient, as per past research [4,8,19], the contact surface model, defined by Coulomb friction law, was applied. By comparing the FEM simulation results obtained from each friction coefficient (0.08, 0.10 and 0.12) with the experimental results, the contact interfaces between the sheet and the tool, defined with a friction coefficient value of 0.10, were in good agreement, which corresponded well with the literature [10,13,14,16].…”