Experimental examination of effects of punch angle and clearance on shearing force and estimation of shearing force using fuzzy logic

A significant challenge faced when using blanking/piercing to machine sheet metal is the handling of the shearing force required for high strength and thick stock. Increased shearing forces lead to the requirement of higher performance expected from the pressing machine and result in increased wear on the punch tool and die. Clearance, employed to increase precision and quality in blanking/piercing operations, affects the shearing force as well. One of the techniques used to reduce the force required is the employment of a punch shear angle. In this study, the effects of punch shear angle and clearance on the forces required for blanking/piercing were examined on a grade of steel broadly used in the manufacturing industry, DC01. Experiments were carried out using five different punch shear angles, namely 0°, 2°, 4°, 8°, and 16°. Six matrices with varying clearance rates (0.4%t, 0.5%t, 0.6%t, 0.7%t, 0.8%t, and 0.9%t) were used in this study, and these clearances were altered by modular matrices on the die. This study shows that shearing forces can be reduced by 80% when 16° punch angle is used. The results of the experiments were transferred to a fuzzy logic model to obtain extrapolated results for intermediate values which had not been obtained from the experiments. The results obtained from the experiments and the output from the fuzzy logic model were compared and found to be highly similar. These results have showed that the model developed using fuzzy logic can be used to determine different shear angles and clearance values

The effects of temperature and strain rate on yielding and springback behaviour of DP1000 dual phase steel

This study aims to investigate the effects of the temperature and strain rate on the yielding and springback behavior of DP1000 advanced high strength steel. For this purpose, material properties were defined using tensile tests at several temperatures (25 °C, 100 °C, 200 °C) and strain rates (0.0083 s -1 , 0.16 s -1 ). Yield loci were estimated by using Barlat-89 yield criteria. Springback behavior is specified by performing V bending tests. No significant effect was observed in the assessment of the effect of temperature on the yield locus and springback. Moreover, it was found that the increase in strain rate increased dramatically the yield locus and springback. © 2018 IOP Publishing Ltd

Strain rate sensitivity and strain hardening response of DP1000 dual phase steel

In this study, strain hardening and strain rate sensitivity behavior of commercial DP1000 dual phase steel have been examined in detail at temperatures of 25 °C, 100 °C, 200 °C and 300 °C, at strain rates of 0.0016 s -1 and 0.16 s -1 . As the strain rate has increased, the yield strength has increased but no significant change in tensile strength and strain hardening coefficient has been observed. As the temperature has increased, the yield and tensile strength has decreased in between 25 and 200 °C but it has showed an increase at 300 °C. The strain hardening coefficient has increased in parallel with temperature increase. It has been seen that the strain rate sensitivity has not been affected by temperature. No significant difference in the hardening rate has appeared in between 25 and 200 °C, but the highest value has been calculated at 300 °C. It has been determined that the fracture behavior has occurred earlier and load carrying capacity on necking has reduced with the increase of strain rate and not significantly affected by temperature. © 2018 EDP Sciences