スギ大圧縮プレス成形中に生じる年輪折り畳み現象

概要

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The large increase in strength properties of wooden specimens arises from a large compression using the closed-die forging method. Upon compression of a wooden specimen with inclined annual rings, folding of the annual rings takes place. Despite the knowledge of a fundamental deformation mode of the wooden specimen that was subjected to large compression perpendicular to grain, conditions leading to folding of annual rings are still debated. Here we report the holding behavior of annual rings in wooden specimens cut out from Sugi (Japanese Cedar, Cryptorneria japonica D. DON.) log, under large compression using the closed-die forging method. Our experiments demonstrated that, when the mean ring angle between the loading direction and an annual ring is less than 45°, holding occurs. Observations by scanning electron microscopy showed that the holding of latewood in the annual ring propagates to that in a neighboring annual ring via the rays. From these observations, we inferred that holding of annual rings propagates to the center of log. The validity of a general criterion for the determination of conditions leading to holding based on the inferred result was confirmed experimentally.
一般社団法人日本機械学会の論文
1997-10-25