Abstract

Claw poles are a key component of automobile generators. The output power performance of the generator is very dependent on the magnetic properties of its claw poles. Plastic deformation is known to significantly change the magnetic behavior of ferromagnetic materials in claw poles. In this paper, changes in the magnetic properties of low-carbon steel, used for claw pole components due to their plastic deformation, were investigated for different strains and temperatures. Ring-shaped material samples were prepared by machining and their magnetic properties were measured. The surface roughness was first evaluated and a machining process with an arithmetic average of roughness Ra 1.6 µm was selected as enabling the lowest measurement error. Hysteresis loops at different applied magnetic fields of the material were obtained for different plastic strains and forming temperatures. The magnetic parameters of magnetic flux density, coercivity, and remanence were obtained and compared with magnetic flux density as the primary focus. Results showed that machining, cold forming, and hot forming all led to lower magnetic flux density, larger coercivity, and smaller remanence. Magnetic flux density showed a sharp decrease at the start of plastic deformation, but as the strain increased, the decreasing trend gradually reached a constant value. The decrease was much larger for cold forming than for hot forming. For example, at 500 A/m, the degradation of magnetic flux density with a reduction percentage of 5% at room temperature was about 50%, while that of hot forming at 1200°C was about 10%. Results of this research may provide a reference for the future process design of hot-forged claw poles.

中文翻译：

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塑性应变和成形温度对低碳钢磁性能的影响

摘要

爪极是汽车发电机的关键部件。发电机的输出功率性能非常取决于其爪极的磁性。已知塑性变形会显着改变爪极中铁磁材料的磁性能。在本文中，研究了低碳钢因爪形零件的塑性变形而引起的磁性能变化，该变化针对不同的应变和温度。通过加工制备环形材料样品，并测量其磁性能。首先评估表面粗糙度，并选择具有算术平均粗糙度Ra 1.6 µm的加工工艺，以实现最低的测量误差。针对不同的塑性应变和成型温度，获得了在材料的不同施加磁场下的磁滞回线。获得了磁通密度，矫顽力和剩磁的磁参数，并将其与磁通密度作为主要焦点进行了比较。结果表明，机械加工，冷成形和热成形均导致较低的磁通密度，较大的矫顽力和较小的剩磁。塑性变形开始时，磁通密度急剧下降，但是随着应变的增加，下降趋势逐渐达到恒定值。冷成型的减少幅度要大于热成型的减少幅度。例如，在500A / m下，在室温下磁通密度的降低百分比为5％时的劣化为约50％，而在1200℃下的热成型时为约10％。