木材・木質材料と鋼棒先端の摩擦面温度

Abstract

木材切削工具の温度上昇についての基礎資料を得るため, ヒノキ, ブナ, ホワイトセラヤ, 合板, パーティクルボードから作製した回転円板に直径3mmの軟鋼棒を押し付けて種々の条件で摩擦させ, そのときの棒の軸方向4個所の温度を熱電対で測定し, 摩擦面の温度上昇と摩擦条件などについて検討した。どの摩擦条件においても, 定常状態における棒の軸方向温度分布は片対数グラフ上で直線となり, この直線の外挿値として先端温度を求めた。円板の種類や摩擦条件 (垂直荷重と速度) によらず, 先端温度は摩擦仕事率とともに上昇し, 両者は上に凸の曲線関係を示した。軸方向温度分布から求めた棒先端への流入熱量は, 摩擦仕事の50%以下であり, 摩擦仕事率が大きくなるとこの割合は低下した。棒の先端部における温度分布を, 実際の接触面積を考慮した数値計算で求めたところ, 外挿による先端温度よりも10 - 15%高い接触面温度が得られた。

This paper describes an experiment to examine the surface temperature of a steel rod of 3 mm diameter rubbed with a rotating disc of white seraya, buna, hinoki, plywood and particleboard at a vertical force of 0.1-0.5kgf and a speed of 1.1-14.0m/s (Fig.1). The temperature of the steel rod was measured with thermocouples of 0.1mm diameter embedded in the rod at distances of 2, 4, 8 and 16mm from the top. Temperatures of the rod rapidly increaesed and soon reached steady states (Fig.2).The relation of the temperature in steady state to the distance from the top was always linear on a semi-logarithmic graph, and temperatures of the top surface were extrapolated (Fig.3). The top temperature increased with sliding speed (Fig.4) and showed a good relationship with frictional power, the product of frictional force and sliding speed (Fig.5). The heat flow into the rod per unit time, which was estimated using Eq.1, was less than 50% of the frictional power and decreased with the increase of the frictional power (Fig.6). The temperatures of the top surface, which were numerically calculated on the assumption that the rod and the disc contact over an area of 1mm diameter, were 10-15% higher than the extrapolated ones (Figs.7 and 8).