在實際加工中，製造商在設計與製造「雙轉子型流體機器」 (Twin-rotor fluid machines)之轉子輪廓時遇到許多困難，例如：幾何參數的反覆修改、初始設計階段難以確定轉子之嚙合間隙分佈、及螺桿轉子加工問題改善，因此，本論文旨在研究具嚙合間隙雙螺桿轉子之幾何設計和製造方法。首先，提出一種具點嚙合特徵(Point-meshing feature)之雙螺桿轉子嚙合間隙計算方法，藉由點包絡原理創生之兩個法向齒條間的最短間距計算，可轉換得出複雜的螺桿轉子嚙合間隙，因嚙合間隙在實務上難以進行量測，故通過不同轉子輪廓上之應用，並與三維CAD模型的測量結果進行比較，以驗證本文所提出之數值方法的通用性和求解精度，更可於三維密封線上呈現易觀測之間隙分佈；而此法亦可應用於變螺距螺桿轉子對的嚙合間隙計算和調整。其次，本論文提出直接將間隙設計於一參數化密封線(Parameterized Sealing Line, PSL)之雙轉子齒廓創生方法，此方法將嚙合間隙沿PSL分佈，並利用參數化定義之封閉式或開放式PSL，逆向生成帶有間隙之兩配對轉子輪廓，亦證實此方法可應用於產生圓錐型轉子的輪廓。最後，本論文針對單螺紋螺桿轉子提出了一種透過端銑刀刀具輪廓修正和位置調整來進行加工誤差補償的方法，並建立多軸數控銑床坐標系統進行銑削模擬，分析端銑刀刀具輪廓和位置對轉子輪廓偏差的影響量以建立敏感度矩陣，基於敏感度矩陣和Levenberg-Marquardt演算法，可經過多次閉循環迭代補償來降低加工轉子輪廓偏差，本文利用一個數值範例，成功修正了由轉子加工專用軟體HPMS (Holroyd Profile Management System)計算出的端銑刀輪廓錯誤，另亦通過考慮端銑刀刀具位置參數的不同組合進行端銑刀刀具輪廓校正來改善轉子輪廓偏差。綜前所述，本論文彌補了過去再創生轉子齒廓時未考慮間隙及點包絡之空缺，並提供改善端銑加工精度之可行性方法。;In practical production, the manufacturers pose challenge for designing and manufacturing the rotor profile of twin-rotor fluid machines such as frequent parameter modification, difficult to determine the clearance distribution at the initial design stage of rotor profiles, and the enhancement of manufacturing screw rotor. Therefore, a study on geometric design and manufacturing methods of the twin-screw rotors considering meshing clearances is presented in this dissertation. Firstly, this study proposes a meshing clearance calculation method for screw rotor pairs with cusp features. The complex meshing clearance can be simply determined by calculating the shortest distance between two normal-rack profiles generated using curve-meshing and point-meshing principles. Clearance distributions are much more intelligible to exhibit on a 3-D contact line and the rotor profile. Due to its immeasurability in practice, the adaptability and the solution accuracy of the proposed numerical method are verified by applications on different rotor profiles and comparisons with measured results from a 3-D CAD model. The meshing clearance in a variable-pitch screw rotor pair and the clearance adjustability are also illustrated through the proposed examples. Subsequently, a parameterized sealing line (PSL) with predefined inter-lobe clearance is presented to generate the rotor profile for twin-rotor fluid machines. Closed or open PSL’s are predefined by explicit equations to generate different rotor profile types. The inter-lobe clearance is directly pre-given and distributed along the PSL to form a pair of rotor profiles with a gap. Further, the proposed method is also able to generate the profile of conical screw rotor. Finally, a compensation method for machining errors through correcting profile and changing installation position of the end-milling tool for single-threaded screw rotor milling is also proposed. The milling process is simulated by an established coordinate system of a multi-axis computerised numerical control milling machine. The effect of end-milling tool profile and position on the rotor profile deviation can be analysed and collected to form sensitivity matrices. Based on these matrices and the Levenberg–Marquardt algorithm, profile deviation is greatly reduced after several closed-loop iterative compensations. In the presented examples, the fault of end-milling tool profile calculated by the Holroyd Profile Management System (HPMS) is successfully solved. Improvements in rotor profile deviations are investigated by considering different combinations of end-milling tool position parameters and by performing end-milling tool profile correction.
