Fig 7 - uploaded by Soheil Bakhshivash
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presents the simulation results for four different bending angles and two different punch tip radiuses (i.e. 1 mm and 3 mm). The results indicate that by increasing either bending angle or punch tip radius, the amount of spring-forward decreases and eventually by maintaining other factors constant, the phenomenon turns into spring-back. The simulation results are validated by that of experiments.
Source publication
Spring-Back/Forward in sheet metals is defined as recovery of elastic strain upon unloading in a deformed sheet specimen. Since this phenomenon can cause alternation in the dimensions of a part, leading to irrecoverable compensations, the operative parameters need to be investigated, thoroughly. To assess spring-forward and effective bending parame...
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Citations
... This finding was similar to the results obtained by Dametew and Gebresenbet, (2017). Bakhshivash et al. (2016) however, reported that the phenomenon of springback or springforward during the bending operation can be minimised by increasing the bending angle in combination with a larger punch tip radius. Bakhshivash et al. (2016) argued that the combination of a large bending angle and a large punch radius can promote homogeneity in the strain distribution along the sheet metal with a reduction in the amount of strain developed. ...
... Bakhshivash et al. (2016) however, reported that the phenomenon of springback or springforward during the bending operation can be minimised by increasing the bending angle in combination with a larger punch tip radius. Bakhshivash et al. (2016) argued that the combination of a large bending angle and a large punch radius can promote homogeneity in the strain distribution along the sheet metal with a reduction in the amount of strain developed. Gattmah et al. (2019) investigated a plate bending process by employing a 3-D explicit finite element model for the simulation of the V-shaped die bending process. ...
The reconfigurable guillotine shear and bending press machine is a dual-functional machine that combines cutting and bending processes in sheet metal processing, minimising the time required for set-up and operating seamlessly. The objective of this study is to carry out the performance evaluation of the cutting and bending operations of the developed machine using physical experimentations with aluminium 7075 sheet metal. The cutting and bending processes were conducted successively using the developed machine under pre-designed operating conditions. The thickness of the aluminium sheet metal was 0.5 mm, while the velocity of the guillotine was kept constant at 0.015 mm/sec. A constant cutting force of 25.6 kN and a constant bending radius of 2 mm as well as varying bending angles (30–90°) and bending forces (5–15 kN) were employed to investigate the total time taken for the bending and cutting operations as well as the effect of the bending angles and bending forces on the springback phenomenon. The lowest bending angle (30°) has the highest springback factor of 1.43 under a bending force of 5 kN, while the highest bending angle (90°) has the lowest springback factor of 1.11 under an optimum bending force of 10 kN. The percentage difference in the time saved using the developed machine ranges from a minimum value of 58.66% to a maximum value of 60.22%. The results show that there is a direct relationship between the average time taken and the bending angles for the bending operation. Conversely, for the cutting operation, a direct relationship was observed between the average time taken and the cut angles. The results obtained also indicate that higher bending angles reduce the springback phenomenon but with an increase in the time taken for the bending operation and vice-versa. The results from the physical experimentation provide insight into the effectiveness of the machine in meeting its service and functional requirements.
Automotive stampings undergo complex strain paths during drawing, stretching, and bending operations which develop large plastic strain gradients within the material. Aluminum sheet alloys are increasingly used for vehicle structure lightweighting, but limited formability and high levels of springback present challenges to the manufacturing and assembly processes. The current work explores the springback levels in AA6016-T4 sheet after pure bending operations. Finite element modeling is performed using both isotropic and elasto-plastic self-consistent (EPSC) crystal plasticity approaches. The EPSC model incorporates backstresses informed by GND content, as measured via high-resolution EBSD. Its predictions are shown to be more accurate than those of the isotropic model. The benefits and limitations of the current EPSC model are discussed.
