航太葉片座標定位與翼形面檢測技術發展

On the Development of the Coordinate Setup and Airfoil Profile Inspection Technique for Blades

徐道賢(Tao-Hsien Hsu)

指導教授 ： 賴景義

國立中央大學/工學院/機械工程學系/博士(2007年)

摘要

葉片是航空發動機中非常重要的零件之一，葉片的幾何造型與製造品質對發動機的性能及壽命有相當大的影響，因此品管檢驗的過程相當重要。葉片在製造加工及檢測過程中，都需要利用設計藍圖上所規範的基準面或基準點來建立座標系統。傳統檢測過程中，座標系統的建立往往都是以人為手動操作的方式來完成，不僅耗時也不夠精確，更別說座標的重現性。研究中針對藍圖所見的眾多類型基準點加以分類，並提出各種基準點的量測方法，達到自動化精確量測的目標。葉片檢測座標主要是還原與加工時相同的座標系統，由於葉片加工完成後座標系統就不存在，檢測時就需依據藍圖重建加工座標系統。研究中亦根據藍圖定義的座標系統發展出三基準平面定座標與疊代六基準點定座標的方法，完整重建加工時的座標系統。

葉片檢測著重於葉片翼形輪廓以及各項尺寸誤差分析，當座標系統建立完成後，需要量測葉片等高度翼形剖面的輪廓以進行檢測，加上翼形面造型特殊，傳統量測方式實不足以應付翼形面的量測。本研究針對翼形面量測方式提出離線量測規劃，提供葉片有原始CAD模型時的量測，當無原始模型或加工誤差較大的葉片也提出兩階段量測規劃，發展等高度量測方法，精確量測翼形剖面，針對翼形前/後緣曲率變化大的部分，也發展搜尋量測法，降低量測資料的不平滑性。

藍圖上僅針對翼形參數作定義及規範公差範圍，要從翼形剖面的量測資料中直接計算各項參數，以及分析翼形輪廓誤差，非常困難。本研究針對葉片翼形發展一套分析技術，主要目的在於自動計算翼形的各項參數以及外型輪廓的誤差分析，透過量測點資料與CAD模型公稱曲線的比對，提出最佳化定位方法，利用在曲線上搜尋與量測點最短距離，以及計算空間轉換矩陣修正座標，反覆疊代達到最佳化定位的流程，依據最佳化的結果進行翼剖面分析技術與形狀誤差分析。

本研究對葉片檢測發展出一套完整的自動化流程，包括(1)葉片基準點量測法：針對不同類型基準點做精確量測，(2)葉片座標定位演算法：還原加工座標以確保量測準確，(3)葉片翼形面量測方法：準確而完整的量測葉片翼形剖面，(4)葉片翼形分析技術：分析葉形各項幾何參數、翼形輪廓度、定位度分析等檢測技術，(5)自動化流程：提高精度、速度，節省時間、降低成本，經過許多葉片量測結果證實其可行性，並已成功應用於國內多家航太製造廠商的葉片檢測與分析上。

關鍵字

三次元量測儀 ； 座標定位 ； 葉片檢測 ； 翼形參數分析

並列摘要

The blade is the most important component in aircraft engines while its geometry and the corresponding manufacturing quality significantly affect the engine’s performance and life time. Therefore, the inspection is very important procedure for quality assurance. However, the reconstruction of the datum planes and the datum points referring to the blueprint and the manufacturing machine is difficult for the initialization of the inspection procedure. The traditional methods are based the operator’s experience and relied on the manually operations. This is not only time consuming but also lacking accuracy. The coordinate reconstruction is very difficult to achieve in this way. This research categorizes several procedures from most kind blades from blueprint to determine the datum points and datum planes for automatic inspection. The purpose of these proposed procedures is to reconstruct the inspection coordinate system as that in the manufacturing stage. Both of three-plane method and six-point iteration method may apply to rebuild the manufacturing coordinate system in the inspection procedure.

The blade inspection focuses on the airfoil profile and the error analysis in the key dimensions. However, the traditional measurement methods may not sufficient to handle the inspection of the sequence of airfoil profile due to the blade design shown in most of the blade blueprint. This study proposed the off-line inspection procedure regarding to the airfoil profile measurement while the original CAD model was provided. A two-stage inspection procedure is also proposed in order to examine the blade with the blueprint only. Regarding to the significant change of the curvature rate in the leading or trailing edges of the airfoil, a searching and measurement method is also proposed to reduce the non-smooth measurements.

It is very difficult to calculate the airfoil parameters and analyze the profile error by the specification in blueprint and the profile measurement data since the uncertainty in the datum planes and datum points. Therefore, based on the objective of automatic inspection and then calculate the airfoil parameters and the profile error analysis. The proposed optimum datum determination method can be achieved by iteration in searching the shortest measurement distance and calculate the transform matrix for coordinate system correction.

Regarding to blades inspection, this study proposed a complete automatic procedure includes (1) Blade datum determination methods for several kinds of blades, (2) Rebuild the manufacturing coordinate system methods, (3) Airfoil profile measurement methods, (4) Airfoil analysis methods, and (5) Automatic inspection methods. The proposed procedure and the corresponding inspection techniques were proved the capabilities in several aero engine blades and successfully applied by several domestic aero industry companies for the blade inspection and analysis.

並列關鍵字

Airfoil profile analysis ； Blade inspection ； Coordinate setup ； CMM

參考文獻

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