摘要：
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According to the bar straightening process features and wear area of straightening roll, the design method of “three-stage concave roll and two-stage convex roll” was put forward to improve the straightening accuracy of two-roll straighter. In the design process, based on the bar deformation rule, the principle of 5εt fitting was put forward to describe the stress-strain relationship more accurately and effectively. On the basis of fitting rule and micro-element method, the stress state of metal inside the bar and the neutral layer offset were analyzed, then the bending moment ratio including hardening coefficient and neutral layer offset was deduced. From the comprehensive analysis of the relation of straightening force with the roller wear, as well as the effects of residual stress and elastic core on the hidden deflection, the range of reverse bend curvature ratio of roller lumbar segment was determined for different bar sizes, and hence the wear of roller surface could be slowed down, and the defect of unstable straightening quality caused by residual stress response was overcome greatly. Based on the proposed theory and method, the specific design example was provided to simulate the straightening process, and each parameter which might affect the straightening accuracy was analyzed. It can be found that the straightening accuracy of the designed roll shape could reach to 0.64 mm/m, the hidden deflection was 0.2024 mm/m, and the prediction accuracy after straightening was less than 0.85 mm/m. The stability and reliability of the bar straightening were guaranteed, and the correctness and effectiveness of the theory and design method were verified.
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