Theoretical and experimental study on determining the reasonable cropping process parameters of precision cropping system

A new controllable rotary bending cracking cropping method, based on V-notch stress concentration, is proposed to address the drawbacks of the metal bar separation process, such as poor cross-section quality and low material utilization. The controlled rotary bending cracking cropping experimental device is developed to implement this method. Subsequently, a mechanical model for the precision cropping process is established using material strength theory, and a load control strategy based on fracture mechanics theory is applied to predict cropping efficiency. Experimental verification is then conducted, with results indicating that increasing notch depth improves cropping efficiency and cross-section quality. Additionally, maintaining constant stress intensity factor amplitude (ΔK = 0.4K_c) and notch depth of 5 mm yields optimal cropping effects. The precision cropping process leverages the fatigue crack propagation mechanism to explain the cropping process, offering theoretical guidance for selecting appropriate parameters in subsequent precision cropping processes.