Recently, a processing technique for applying plastic deformation to a solid wood has been developed. In this study, in order to clarify the effect of die-angle on the extrusion force of a solid wood, the extrusion load with or without lubricant for different die angle was investigated. Solid woods (Japanese cypress) were impregnated with thermoplastic binder (acrylic resin) to improve its fluidity during extrusion. To increase affinity with acrylic resin, the woods were hydrophobized by acetylation before the impregnation. Then the impregnated woods were extruded in a radial direction through the square-shaped dies having different angle (2α = 20°, 30°, 40°, 50°). The results obtained were as follows: The extrusion load was clearly decreased by using the lubricant in every die angle. The results of the no-lubricant condition showed that the extrusion load increased with the decrease in die angle. On the other hand, the extrusion load was little affected by the die angle in the lubricant condition. These results indicated that the extrusion load was strongly affected by the friction between the wood specimen and the tapered die in the no-lubricant condition. Assuming that plane strain condition (no strain in the longitudinal direction of the material) applies to the extrusion, the experimental result was well explained by the theoretical result.
