Detection of Tribological Condition during Sheet Metal Forming Using Fractal Property of Acoustic Emission

作者：Hayakawa Kunio^*; Saito Kazumi; Nakamura Tamotsu; Tanaka Shigekazu

来源：Steel Research International, 2010, 81(9): 702-705.

• Acoustic emission
• Tribo-simulator
• Sheet forming
• Friction
• Temperature
• Stainless steel
• Galling

A new method for detecting galling during sheet metal forming processes using the fractal property of acoustic emission (AE) was examined. For the purpose, the AE measurement system was equipped with the tribo-simulator for measuring fractal property of AE. The fractal dimension of AE amplitude was measured with friction coefficient and temperature rise for stainless steel sheets with and without lubricants. Four kinds of mineral oil having various viscosities VG1000, VG100, VG22 and VG2 were employed as the lubricants to examine the effect of viscosity on tribological conditions. No galling was observed when using VG1000 that has the largest viscosity in the present experiments. The fractal dimension was observed above 2.0. In two cases with VG100, though the friction coefficients were below 0.07 in both cases, a sudden decrease of the fractal dimension into below 2.0 was observed in one case, in which the galling was observed after the iteration of 8. No galling occurred in the other case, in which the fractal dimension was above 2.0 during the experiment. In case with VG22, galling observed after the iteration of 5, and the fractal dimension was measured below 2.0 from the first although the increase of friction coefficient was observed after the iteration of 30. In cases with VG2 and no lubricant, severe galling occurred from the early stage, and the fractal dimensions were observed below 1.0 during the experiment. The galling was prone to occur when fractal dimensions become below 2.0, and that the change in fractal dimension responded more sensitively to the occurrence of galling than the friction and temperature.

• 出版日期2010-9