鐘錶元件精密車削關鍵技術之開發

key Technology Development for Precision Turning of Watch Component

林義祥(Yi. Hsiang. Lin)

指導教授 ： 林盛勇

國立虎尾科技大學/工程學院/創意工程與精密科技研究所/碩士(2010年)

摘要

鐘錶錶盤元件加工後表面紋路之尺寸精密性與分布均勻性，關係到當手腕不同角度搖晃鐘錶時投射在其表面上光線折射之顏色均勻度與美觀，此品質進而影響其附加價值與售價。錶盤為鐘錶之門面元件，其優越的性能連帶高附加價值之創造。
本研究先對車床結構進行模態實驗，利用單點輸入單點輸出量測法，固定一敲擊點而依次激振於所有響應點，每次量測一個響應點的頻率嚮應函數，如此將所有量測的頻率響應函數資料整合匯入模態分析軟體ME ‘scope，進行模態分析，以求得結構之模態特徵參數與振型。接著使用Renishaw雷射校正儀，作為線性軸定位與旋轉軸定位檢測的儀器，來量測機台的真直度與垂直度等，做為結構校正於實際車削精密度改善之參考。再來模擬與尋找不同車刀刀具幾何與切削條件之參數組合以獲得較佳端面車削之表面品質，並經由端面車削實驗來加以驗證。結果顯示車床結構模態1與模態2振型主要發生在主軸頭座與刀具溜座，此振型對切削加工影響較大，因而避開此自然頻率來規劃本研究加工銅合金的切削範圍。刀具幾何方面，餘隙角與刀面斜角過大時，搭配較低的進給率，不論切削速度提升多少，表面品質皆較差。但當此二具角度較大搭配進給率的提升，表面品質會有些微的改善。刀面斜角過大會加快切屑的移除，造成切屑提早捲曲而堆積於刀刃與加工面之介面，造成排屑不易進而刮傷表面，導致表面品質變差。經由以上針對結構製程、參數與刀具角度三者系統性的探討，發現結構的剛性與移動精度不錯，其對於錶盤表面端車品質影響不大，但結構自然頻率的求得，可作為製程參數規劃的參考，因此製程參數與刀具角度的搭配選擇顯得較為重要，選用較小的餘隙角與斜角，搭配高進給率與切削速度，可得到較佳的表面紋路均勻性與美觀品質，此元件表面優越性能，符合鐘錶業要求之關鍵技術。

關鍵字

錶盤 ； 表面紋路 ； 刀具角度 ； 製程參數 ； 工具機結

並列摘要

After the processing of a watch dial component, the dimension precision and uniformity distribution on its surface pattern have a connection with its color distribution and attractiveness. That is, one can see the different image pattern reflected by the dial surface of a watch at differed orientations. Therefore, the quality of color distribution and attractiveness would have an impact on its additional values and prices. The dial is the exterior of the watch and its additional value of its advantage would be created as well.
This research aimed at conducting modal testing to investigate the structure dynamics of a lathe. This testing was done by a fixed impact point and then being excited consecutively on each response point through the application of the single input/single output method, and the frequency response function (FRF) on a response point is measured every time. All the data of the FRF measurements would be collected and input into a modal analysis software called ME ‘scope and the modal analysis was performed accordingly. The purpose of this procedure is to determine the characteristic parameter related to structure mode and modal shape. In addition, the application of laser interferometer was used to examine linear axis orientation and rotation axis positioning. And the straightness and the squareness for their movement paths of a lathe would be investigated. The results would be taken as a reference for structure calibration and accuracy improvement in turning. Application of numerical simulation tries to investigate the influence of chip formation situation under different tool-angle geometry and cutting parameter combination on the surface quality of the dials. The results would be also validated by an experiment of face turning
The results indicated that Mode 1 and Mode 2 of a lathe structure primarily occurred at spindle headstock and tool slider. These modal shapes have much more influences on the dial surface creations during turning. Therefore, these natural frequencies should be avoided for the planning cutting conditions in face turning of the copper alloy. Furthermore, on the tool geometry aspect, when larger clearance and rake angles in conjunction with lower feed rate, no matter how much cutting speed was enhanced, the quality of the dial surface is not as well as before. However, when these two larger angles combined with the larger feed rate, the quality of the surface would slightly be improved. The larger rake angle would further result in a quicker chip removal. And then the chip would be piled up on the interface between cutting edge and the machined surface. The consequence would be that the subsequent chip sliding was not easily and then scratched the dial surface, which would have the consequence in the deterioration on surface quality. Through the systematic investigation among structures, process parameter and tool angle, the total results indicated the stability of structure rigidity and precision of movement path, which had only a little impact on the quality of dial face turning. However, the structure natural frequency could be used as a reference for process parameter planning. Therefore, the combination of process parameter and tool angle is of more essential. By using smaller clearance and rake angles along with the higher feed rate and cutting speed would gain a better surface pattern with uniform distribution and attractiveness. Finally, the surface of the dial component is superior to its performance, which would be the key techniques corresponded to the request in the watch industry.

並列關鍵字

dials ； surface pattern ； precision face turning ； cutting-tool angle ； process parameter ； machine-tool structure

參考文獻

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[29]劉導淳，有限元素法應用於龍門磨床之結構動態分析，第五屆中華民國振動與噪音工程學術研討會，1997。

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[2]Patrik Dahlman, Fredrik Gunnberg, Michael Jacobson, 2004, The influence of rake angle, cutting feed and cutting depth on residual stresses in hard turning, Journal of Materials Processing Technology, Vol.147, pp.181-184.