ダイヤモンドコーテッド金型による
AZ31マグネシウム合金板のドライ絞りしごき加工

抄録

Dry press forming, which means press forming without lubricants, is an attractive forming technique for the zero emission of lubricants. As one of the dry press forming techniques, the application of dies coated with a CVD diamond film in forming tools has been proposed for their high tribological properties, abrasion resistance and heat resistance. In this study, using diamond-coated dies AZ31 magnesium alloy sheets were dry-deep-drawn and ironed to investigate the tribological properties of diamond-coated dies and the formability of magnesium alloy sheets. A friction test was conducted to confirm the tribological property of the diamond-coated dies, and the friction coefficient of the diamond-coated dies was compared with using the lubricants. Dry deep-drawing ironing tests were carried out under the following experimental conditions: 10% ironing ratio at a die temperature of 200°C. In addition, the forming limit using diamond-coated dies was compared with that using noncoated dies with a conventional lubricant. From the results, the deep-drawing ironing process was feasible using diamond-coated dies. Moreover, a 20% reduction in drawing force was confirmed in comparison with the use of a traditional lubricant (MoS₂). Furthermore, it was observed that the surface roughness of a wall part of the formed-cup using the diamond-coated dies was 0.38μmRz. From these results, the feasible use of the diamond-coated dies was suggested.