Study on the pre-shearing cropping process of steel bars
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A new type of bar-cropping process, termed the pre-shearing cropping process, which can improve billet cross-section quality has been proposed in this study. The new cropping process was realized by using a servo-controlled press. A low-carbon steel 20Cr as-received and a medium-carbon steel SCM435 as-annealed were used to test the process. A group of pre-shearing cropping experiments was carried out with different pre-shearing values of 6.67, 13.33, 20.00, and 26.67% under a pre-shearing speed of 10 mm/s and a cropping speed of 600 mm/s, and conventional cropping experiments with different cropping speeds of 200, 400, and 600 mm/s were conducted for comparison. The quality of the cropped billets was evaluated quantitatively using the indices of surface flatness, ovality, and incline angle. The effect of cropping speed on the conventional process and the effect of pre-shearing on the pre-shear cropping process were investigated in detail. The experimental results showed that the pre-shearing cropping process could improve the quality of the cropped billets and reduce the maximum cropping load slightly compared with the conventional cropping process. Finally, the mechanism of the pre-shearing cropping process was furtherly analyzed by finite element simulation and tried to be summarized.
KeywordsPre-shearing Cropping process Surface Flatness Ovality Incline angle Billet Forming load
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