臺灣博碩士論文加值系統

滾珠螺桿為目前精密機械設備上最常使用的傳動元件，包括精密工具機、產業機械、電子機械及輸送機械等。有鑑於其應用皆在高精度控制，滾珠螺桿在製程即有高精度的要求，而具有可加工淬硬材料及極精密加工特性的砂輪研磨即成為目前製作滾珠螺桿極重要的製程。本論文將探討研磨切削製程的動態行為及模擬工件經加工之表面粗糙度。所探討的系統包含工件及其支撐、砂輪及其主軸。工件的支撐包含研磨機頭座及尾座的頂心及中心支撐架，而砂輪主軸考慮一具靜液壓軸承之主軸。
本研究將應用能量法結合大域模態假設法推導出螺桿受移動研磨切削力作用的運動方程式，再由朗吉-庫塔 (Runge-Kutta Method) 逐步積分法求得系統在移動負載下的動態響應。最後利用高斯分佈法模擬砂輪磨粒高度的分佈情形，考慮加工時螺桿及砂輪的位移，計算各個磨粒的作用深度，模擬螺桿加工後的表面粗糙度。
數值結果顯示，研磨過程中工件有無加入支撐架抑振對研磨過程的振動有明顯影響，可降低約90%的振動量。影響研磨切削力最大的參數為切削深度，切削深度和最大振動量呈線性關係，可藉已知的加工經驗預測加工振動情形。使用砂輪研磨之目的在求得良好工件表面，磨粒粒度的影響大於磨粒組織度。

Ballscrews are the most common transmit element used in precision machines now, including precision machine tools, industrial machinery, electronic machinery and transport machinery. According to the application all in high precision, ballscrews need high class asked at its manufacture process. Due to the characteristics of manufacturing hard materials and precise manufacturing process, grinding can be used for manufacturing ballscrews. The dynamic behavior of a workpiece under a moving grinding force will be discussed and the workpiece surface roughness will be simulated in this study, and the system is inclusive of the workpiece, headstock center, back poppet, center supports, grinding wheel and the grinding wheel spindle with hydrostatic bearing.
The system equations of motion are derived by Lagragian approach combined with GAMM in this study. The transient responses of the system due to a moving force are evaluated by applying Runge-Kutta method. Then we simulate the grain height distribution on the grinding wheel, considering transient response on the ballscrews and the grinding wheel. Last, the workpiece surface roughness could be simulated via calculating the depth of all working grains.
On the basis of the results, the vibration in grinding process has obvious influence by using a center support. The center support can reduce 90% vibration. The most important parameter in the grinding process is the depth of cutting. An equation can be found to predict the maximum response by the depth of cutting. The purpose of using grinding process is the workpiece need fine surface roughness. The workpiece surface roughness is influenced by the grain size more than the structure numbers can be.

I. INTRODUCTION 1
1.1 Motivation of Research 1
1.2 Literature Review 1
1.3 Outline 3
II. SYSTEM EQUATION OF MOTION 5
2.1 Modeling of a Ballscrew 5
2.2 Modeling of a Grinding Wheel and Its Spindle 7
2.3 Modeling of a Grinding Force 11
2.4 Lagrangian Approach 14
III. SIMULATION SURFACE ROUGHNESS 24
3.1 Simulation the Grain Distribution 24
3.2 Determination of the Workpiece Roughness 26
IV. NUMERICAL RESULTS AND DISCUSSION 29
4.1 Introduction 29
4.2 Comparison of Number of Center Supports 33
4.3 Comparison of cutting depth 46
4.4 Comparison of Parameters of the Center Supports 60
4.5 Comparison of the Grinding Wheel Topography 76
4.6 Comparison of Workpiece Surface Roughness 83
V. CONCLUSION AND FUTURE STUDY 95
5.1 Conclusion 95
5.2 Future Study 96

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