| Popis: |
In the fabrication process of medicine tablets, working speed of the tablet compressing is an important factor to realize the high fabricating efficiency together with the low cost. Thus, a number of loadings would be applied with very high frequency to tips of a couple of compressing punches. Sometimes, the tablet compressing speed exceeds 150 tablets per second. Due to such a circumstance, the very high cycle loadings are applied to the tips of the compressing punches making medicine tablets. The high strength steel of KNS-ES was specially designed and fabricated for the particular use as the compressing punches. In this study, very high cycle fatigue tests were performed in the loading type of rotating bending in order to obtain the fundamental S-N property of this steel. Based on experimental results, the S-N property in giga-cycle regime was discussed including the effect of the residual stress on the S-N properties. Consequently, the duplex S-N curves were clearly found, but the surface-induced fractures were often found in the fatigue data belonging to the second S-N curve in the longer life region. |
