A study of the influence of high-speed press bottom dead-center displacement and fluctuation on motor core products

Abstract

Motor cores demand precision for the purpose of product shape refinement and to increase the performance. To enhance the lamination method and the efficiency of the product, the material thickness is becoming thinner. In addition, press machines require a mass-production system with high precision. In an experiment, the effects of the displacement and fluctuations of the bottom dead center on a high-speed press were investigated. The experiment was carried out by sequentially increasing the press speed from 50 to 130 and 270 spm. The bottom dead-center displacement levels of the press were 0 mm at 50 spm and 0.05 mm at 130 spm. At the speed 270 spm, the bottom dead-center displacement increased from 0.1 to 0.15 mm. As a result of analyzing the types of bottom dead-center fluctuation, a change from 61 to 273 μm was considered. The required height to guarantee the quality of the motor core embossing outcome is 0.05 mm, which can be realized by fine adjustments of the mold at a fluctuation level of 61 μm. The embossing process leads to piercing at the fluctuations of 85–89 µm and 273 µm, requiring a total press overhaul or partial repair. In this paper, as the press speed increases, the bottom dead-center displacement increases and the bottom dead-center fluctuation affects the forming results of the embossing process.