鎚擊式釘槍握把形態及握持舒適性評量之研究

Evaluation on Handle Design and Gripping Comfort of Hammer Tacker

對於木工裝潢及營造建築等作業員而言，鎚擊式釘槍（Hammer Tacker）乃是必備的工具。在不良的握把形態與握持方式的長時間使用狀態之下，容易造成手腕尺偏與橈偏，進而形成累積性傷害。本研究以“彎曲握柄以保持使用者手腕正直＂的手工具設計原則，提出5°、20°、35°、50°四種握持角度，及適合強力施力的握把形態。針對垂直式及水平式槌擊兩項典型工作項目，以EMG生理肌電圖紀錄實驗過程中，受測者手部各肌群之肌電訊號變化，並於實驗後填寫主觀評量表。分析結果發現：（1）各部位肌力變化中，普遍顯示5°~20°區間肌力負荷有較大降幅，在20°~35°區間則無顯著差異性，直到35°~50°區間肌力負荷才又出現下降的趨勢。可知在四種握持角度的鎚擊式釘槍中，操作50°握持角度肌力負荷為最低。（2）以迴歸分析推估大於握持角度50°的%MVC變化中發現，平面與垂直式打擊作業各部位%MVC最低點落在52°~62°之間。（3）在主觀手部酸痛程度與操作滿意度分析結果發現，一致顯示操作50°鎚擊式釘槍有較低的酸痛程度及較高的滿意度。但在觀察受測者實驗前的嘗試揮擊過程中發現，一般的受測者對於現有直式榔頭的打擊作業方式已習以為常，在操作過程中彎屈手腕來適應手工具已成為一種習慣。因此，在與受測者說明實驗過程與實驗目的同時，先行教育使用者正確的操作方式，避免以彎曲手腕進行打擊，受測者便能逐漸適應其施力方式，並發覺其中差異性。

A hammer tacker is an essential tool for workers in the fields of carpentry, interior decoration, and construction. Improper handle design and prolonged use may cause damage to the arm and wrist, resulting in cumulative trauma disorders. This study evaluated the handle design of hammer tacker that aims to provide gripping comfort and avoid physical harm. Hammer tacker of four different gripping angles, 5°, 20°, 35° and 50° and with handle design suitable for applying strong force were tested. Hammer use in two typical working processes, vertical and horizontal orientation, were examined. In the experiment, changes in EMG signals measured from the subject's hand while using the hammer tacker were recorded. After the experiment, subjects were asked to fill out a questionnaire concerning gripping comfort. Results of the analysis on the changes in muscle strength show the following. （1） Muscle strength required for working drops obviously in the zone between 5°and 20°, followed by no significant difference between 20° and 35°, and drops again in the zone between 35° and 50°. These findings imply that hammer tacker with gripping angle of 50° required the least muscle strength for working. （2） Regression analysis on the changes in %MVC variation for angles exceeding 50° reveals that the minimum %MVC falls between 52° and 62° in both vertical and horizontal orientations. （3） Subjective responses collected by the questionnaire survey show that gripping angle of 50° requires the least muscle strength of the wrist and hand for working while giving the greatest comfort. Hence, both experimental findings and survey results agree that the optimum gripping angle for the hammer tacker handle should be 50°.