榔頭之人因設計因素研究-以『Plumb』為例

Abstract

由於『家庭DIY裝修佈置』市場蓬勃發展，以往只在工地被使用榔頭，漸漸為一般大眾使用。有鑒於工地專業工人與一般大眾之工作模式及體能有所差異，將專業工作手工具市場，與『家庭DIY裝修佈置』手工具市場分開，並針對DIY手工具市場，設計專用的手工具是有必要的。 本研究先透過實驗，分析在使用榔頭從事榔頭及釘作業時，手部的肌肉收縮狀況，並了解專業與一般人的工作模式的差異。接著改變榔頭重心位置，以及握柄角度兩個設計因素，討兩個變因正交之後，對於使用結果影響；本研究製作21把實驗用樣本，分別由重心10~18公分(間隔為4公分)，與握把彎曲角度-15~15度(間隔為5度)兩項變因的正交而設計。實驗中主要以EMG儀測量肌肉收縮的狀況，並以舒適度(由EMG儀所測得受測者橈側伸腕肌的收縮百分比值)、使用效率(及入一根鐵釘所需要的時間)、以及專家工作模式趨向(由EMG儀所測得受測者肱三頭肌的收縮百分比值)三個指標衡量各樣本的差異。經過實驗、分析、討論之後，得到以下結果： (1) 一般使用者與專業使用者在擊釘作業時，工作模式明顯不同。一般使用的手臂揮動幅度較專業使用者小，工作效率較差且手腕的橈、尺偏較大。 (2) 經過樣本的製作與實驗分析之後，實驗樣本中，在舒適度與專業的姿勢傾向上，重心位置距離榔頭頭部18公分，握柄角度-5度的榔頭，具有最好的效果，而擊釘作業的績效的方面，則是重心位置距離榔頭頭部14公分，握柄角度-5度的榔頭，具有最好的效果(負值的角度為榔頭槌面的反向)。 (3) 經過回歸分析之後，可得到由舒適度到效率趨勢的變化時，對應於榔頭重心位置與握柄彎曲角度分佈圖形，可提供設計師設計新式樣榔頭時，針對不同舒適度與效率需求，在握柄角度與配重上做調整的參考。

Hammers, the commonly used tools at construction sites, now are gradually implemented in the fixing and decorating works at home. Concerning the difference of muscular strength and performance skill between the professional workers at construction site and general people who seldom use hammer, there may be an urgent need to design a home-use hammer for the DIY market besides the matured professional tool market. This study has controlled the center of gravity and the handle-angle of a hammer to see how these two variables affect the non-professional users in the task of knocking nails. Twenty-one testing hammers were constructed according to the three different position of center of gravity and seven controlled angles of handle, from -15 to 15 degrees with a 5 degree interval. Non-professional subjects were recruited to complete a nail knocking task in the experiment. We measured the EMG signals as the main indicator to determine the degree of contraction of related subjects’ muscles when they were conducting the nail knocking task. Two criteria concluded from analyzing the EMG signals, criteria of comfort and tendency to induce professional posture, as well as the criteria of efficiency, the measured elapsed time to complete a task were adopted to judge the performance of varied hammer designs tested in this experiment. The result of the experiment was summarized as follows: (1) Comparing to the professional workers, general people showed a smaller swing of fore-arm movement, as a result, were less efficient and caused more ulnar deviation and radial deviation in hammer operation. (2) The hammer with center of gravity located at 18 cm from its head and handle angle of -5 degrees showed the best effect on comfort and tendency to induce professional posture criteria. As efficiency was concerned, the best hammer was the one with the center of gravity located at 14 cm from its head and handle angle of 5 degree. (3) By regression analyze, a convenient graph was concluded to tell hammer designer how to design a hammer with proper combination of the two important features of hammer: location of the center of gravity and handle-angle for different users.