Annealing process optimization of 3D coil core based on annealing simulation experiment and thermal mechanical coupling model

Annealing is necessary to reduce the residual stress and no-load loss of 3D coil core. In production, because monitoring the changes in temperature and stress of 3D coil core in real time is impossible, the trial and error method is usually used to formulate the annealing process parameters. The annealing simulation experiment of grain-oriented electrical steel (GOES) is carried out to explore the influence of soaking time on iron loss and magnetic flux density. The mechanical properties of GOES are tested, and the true stress-strain curves at different temperatures are obtained. Based on the existing research and experimental results, an anisotropic thermal mechanical coupling model of 3D coil core is established. An optimization scheme of 3D coil core annealing process is obtained, considering the temperature difference, stress and strain. According to the onsite measured parameters, the annealing process is simulated and optimized by the coupling model. Results show that the total annealing time is shortened by about 18.7% without increasing the stress and strain. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Annealing is necessary to reduce residual stress and no-load loss in 3D coil cores. In the absence of real-time monitoring of temperature and stress, the trial and error method is commonly used to determine annealing process parameters. An annealing simulation experiment was conducted on grain-oriented electrical steel (GOES) to investigate the effect of soaking time on iron loss and magnetic flux density. The mechanical properties of GOES were tested and true stress-strain curves at different temperatures were obtained. Based on existing research and experimental results, an anisotropic thermal mechanical coupling model of the 3D coil core was established. An optimization scheme for the annealing process of the 3D coil core, considering temperature difference, stress, and strain, was obtained. The annealing process was simulated and optimized using the coupling model based on onsite measured parameters. Results show that the total annealing time was shortened by approximately 18.7% without increasing stress and strain.