螺桿轉子對(Screw rotor pair)係為雙螺桿流體機器中關鍵之零組件，兩 轉子可為相互接觸或互不接觸、以相反方向運轉，而轉子齒形與兩轉子間 嚙合間隙(Meshing clearance)設計對機器性能至為關鍵，然而在實務中，雙螺桿流體機器之螺桿齒廓種類多、曲率變化大、兩螺桿面間嚙合間隙分佈不易量測，過去文獻中亦缺乏一套較為通用之嚙合間隙分佈計算方法。故本研究提出一套通用之雙螺桿齒間間隙數值計算方法，基於離散方法、將 理論設計或三次元量測儀取得之轉子齒形點資料進行整理，把曲率變異過 大之轉子齒形分類為共軛、非共軛曲線段，進行齒間間隙分析、及呈現沿 接觸線上之間隙分佈，以更直觀的方式呈現轉子嚙合時、齒面間之流體洩 漏帶(Fluid leakage band)，此外，亦示範利用間隙分析結果逆向創成一對不具間隙之共軛轉子齒形。透過數值範例，以不同轉子齒形、不同導程設定，驗證所提方法之正確性，更證明此方法可考慮裝配誤差計算齒間間隙。;The key component in twin-screw fluid machines is a pair of screw rotors, which rotate parallelly around the respective axis in the opposite directions. Two meshing rotors may be with or without contact. Design on rotor profiles to form a better meshing clearance band is a main factor to affect the machine performance. In the practical application, it is difficult to measure the clearance distribution between the surfaces of meshing screw rotors due to the variety in rotor types and the large curvature variation on rotor profiles. In view of this, this study proposes a general numerical method to evaluate the meshing clearance for twin-screw rotor pairs. Discrete point data of rotor profiles obtained from the theoretical design or the 3-D coordinate measuring machine (CMM) is used to conduct the meshing clearance analysis and the 3-D clearance presentation along the contact line, after being classified into the conjugated and non- conjugated profile segments. The fluid leakage band can thus be presented more intuitively. In addition, a pair of conjugated rotor profiles without clearance is able to generated by correcting the calculated result of meshing clearance. As results shown in the numerical examples, correctness of the proposed method is verified through several cases of rotor profiles with different tooth profiles and different leads. It is also proved that this method is suited to calculate the meshing clearance considering the assembly error of rotors.
