手工具による木材表面形成に関する研究 : ぜんまいがんなによるろくろ旋削した木材の表面観察

The turning is one of the handiwork, and this technic has been done from old times. In turning, the wood face turning lathe (rokuro in Japanese) is used. There are two types in rokuro turning, one is peripheral turning and the other is face turning (see Fig.1). The surface formed by the expert in rokuro turning has clear grain and is good glossy. But this tool (zenmaiganna in Japanese) that is used in rokuro turning is very simple structure, but machining mechanism by rokuro turning is very complicate because of the big change of grain direction and cutting speed during machining. Cutting angle and bias angle must be varied in correspondence with their change by expert judgement.
Therefore there are only a few date about rokuro turning so far.
In this paper, SEM observation of rokuro turning surface and analysis of the locus of tool at the face turning were done. Obtained results are as follows:
1) In the case of finished surface, cell cavities were filled with sand shavings and surface was very smooth. This smoothed surface is very good condition for coating treatment.
2) The state of machined surface is affected by cutting speed. In the case of face turning, cutting speed is big difference between near and far from the center of rotation for work material. The wooly grain occur near the center. To the contrary, the wooly grain don't occur at some distance from the center, and each fiber is recognized clearly.
3) The locus of tool cusp at the face turning is the circle with center at the point which is projected the support on the ctting plane (see Fig.11).