Effects of moisture content and grain angle on the mechanism of wood slicing along the grain
1998
Ohya, S. (Hokkaido Univ. of Education, Sapporo (Japan))
On wood slicing along the grain, especially when grain angle is near 0 degree, advanced check easily develops. Therefore, the slicing process is affected largely by grain angle. Little attention, however, has been given to this point. In this study, cutting tests were done under three grain angle conditions (0, 3, 6 degrees). Effect of grain angle to curl radius, thickness variation in each veneer, cutting forces (horizontal force and vertical force), and "the average amplitude" of cutting forces, which was defined by eq. (5), was examined. Effect of moisture content was also examined, because it seems reasonable to suppose that occurrence condition of advanced check would after with the change of wood mechanical properties. Moisture content conditions used in this study were air-dry and water-saturated. The following results were obtained: 1) At air-dry specimen with large depth of cut, smaller grain angle caused smaller cutting forces and much larger curl radius. On the other hand, at water-saturated specimen, cutting forces and curl radius were effected only a little by grain angle. 2) Variation of veneer thickness was larger on slicing of air-dry specimen than on slicing of water-saturated specimen. 3) Variation of veneer thickness was little effected both by depth of cut and grain angle, when the depth of cut ranged between 2 mm to 5 mm. 4) All of the above results suggest that air-dry specimen slicing has an advantage at the point of machinability and curl radius, but has a disadvantage at the point of variation of veneer thickness. 5) "The average amplitude" of cutting forces became smaller with the increment of grain angle. 6) "The average amplitude" of cutting forces and standard deviation of veneer thickness had linear relationships
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