57 巻 (2016) 660 号 p. 22-27
In the ironing of stainless steel cups using a cermet die having lubricant pockets, the conditions of optimum lubrication for attaining low friction were investigated. On the surface of the die, fine lubricant pockets are made by polishing of the shot-peened surface. The effects of lubricants and ironing speed on the ironing load and limit were obtained. The thickness of remaining lubricant on the sidewall of the ironed cup was measured by mixing a fluorescence oil in the lubricant. When the amount of lubricant was sufficient and the ironing speed was high, the ironing load was lower than that of a die having a polished surface and greater thickness of remaining lubricant on the sidewall of the ironed cup. In repeated ironing, the surface roughness of the ironed cup for the die having the lubricant pockets was almost constant, whereas the roughness for the die having a polished surface increased.