チェーンソーの保持方法と振動の関連について

Abstract

伐木造材作業時にチェーンソーが作業者に与える振動負担を物理的側面から把握しようとした。すなわち, まず作業時に出現するチェーンソー保持方法について分析し, これら種々の保持方法の基本として片手保持での肘の角度, 握力がチェーンソーハンドルバー部の振動特性に与える影響を明らかにした。・作業者がチェーンソーを保持する方法は, 伐倒作業時には肘の角度が90°に近く, 玉切り作業時には肘の角度は180°に近い。また, 枝払い作業時は変化が大きく, 持続的な保持方法はとられない。・チェーンソーを把持する握力がハンドルバー部の振動特性に与える影響は大きく, その力が大の時, 作業者への振動負担は大きい。・肘の角度がハンドルバー部の振動特性に与える影響は握力のそれに比し小さいが, 角度が90°の時作業者への振動負担は大きい。

Protecting operators of chainsaw from the vibration hazards, we investigated the relations between the posture operating chainsaw and the load by vibration to the human hand. This report consists of experiments, the one is the analysis of several postures operating chainsaw in forest work and the other is the measurements of the resonance frequency and the amplitudes of acceleration at the isolated chainsaw's handle in several conditions of holding it with left hand. The factor of holding condition estimated the force griping handle and the angle of the elbow. From the results of experiments, the followings were observed. (1) The posture of operating chainsaw was that the angle of the elbow was about 90° during the felling work and it was about 180° during the bucking work. During the trimming work, the posture of operating chainsaw had too many styles to represent the fundamantal posture. (2) When the elbow was angled rightly in holding chainsaw, the vibration hazards increased. Besides, griped chainsaw tightly, it increased much more. So, the posture during the felling work have an unfavorable influence on human hand and the health of worker.