Analysis of bending mechanism and spring-back characteristics in the offset Z-bending process

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

“…Reversed bending stress is the stress generated by the bending phenomena, where the generated compressive and tensile stresses are formed on the opposite side of those formed in the bending allowance zone. These stress distribution analyses generally agree with those reported in the literature [14]. For the aforementioned stress characteristics, the same level of generated bending stress on the bending allowance zone and the reversed bending stress on legs could be obtained as …”

“…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]. The other process parameter conditions were designed as shown in Table 1.…”

“…Bend Angle Figure 8 shows a comparison of the stress distribution analyzed in the workpiece, before unloading, with respect to the various bend angles in the cases of the U-bending process, with and without pressure pads. With the use of pressure pads, according to past research [14], the bending and reversed bending stress characteristics were generated in the bending allowance and in the leg zones. It could be explained that the changes in bend angle directly resulted in changes in the bending allowance zone over the bend radius.…”

“…As the main problem in the bending process, spring-back is the key factor that affects the quality of complicated U-shaped parts. A great deal of research has been conducted on this in the past [8][9][10][11][12][13][14][15][16][17][18]. Jiang and Dai [8] proposed a novel model to predict U-bend spring-back and time-dependent spring-back for a high-strength low-alloy (HSLA) steel plate.…”

“…The predictions of spring-back in cases of the U stretch-bending process [12], and in the pre-strained U-draw/bending process [13], were investigated. Thipprakmas and Phanitwong [14] used the finite element method to analyze the bending mechanisms and spring-back/spring-go characteristics in various U-bending processes. Seong et al [15] analyzed the core shear stress in welded deformable sandwich plates to prevent de-bonding failure during U-bending.…”