2006 Volume 55 Issue 8 Pages 772-776
The purpose of this study was to propose a method of determining the aging of wood by measurement of cutting resistance. To clarify the effect of the aging of wood on the cutting resistances, it is necessary to focus on the way the restorators judges the age of wood material by taking into consideration the cutting process and the way of using the chisels (nomi).
In this paper, aging is defined as “slow oxidation caused by oxygen in the air”. Base on the temperature-time conversion law, an accelerated aging test was performed by heat treatment at 180°C for 0, 120, 300, 600, 720, 2160, 3600, 5040, 7200minutes respectively to obtain different levels of accelerated aging wood samples.
When restorators of Buddhist sculptures restorate ancient statues, they face various qualities of timber, according to the tree species and the age of the material used for the statue. They make decisions by visual inspection. Thus the experience and judgement of the Japanese restorators is one of the key conditions to measure the cutting resistance and types of chip formation.
The orthogonal cutting test of cross, radial and tangential section were made to examine the relationships cutting resistances and treatment time of the accelerated aging of wood materials. The results were summarized as follows :
1) The cutting resistances fell with increasing the accelerated aging treatment time. The cutting resistances dropped sharply in the early stages up to 1000 minutes treatment, and then reduced by 80% at 7200minutes treatment.
2) The types of chip formation changed from flow type to powder with increasing the accelerated aging treatment time.
3) The forces in cross sectional cutting with clearance angle 5° were three times in value with clearance angle 1°. The forces in orthogonal cutting test in radial and tangential section were almost same in value at clearance angle 1° and 5°.