A virtual inspection framework for precision manufacturing of aerofoil components

Tao

2015

Blade geometry plays an extremely important role in the aerodynamic performance of aero-engine. However, in the adaptive machining process of a near-net-shape blade, it is important for an application engineer to reconstruct an actual profile with high-precision measurement data in a short time. This paper presents an efficient measurement to meet the requirement for digital information in the adaptive machining, which is also intimately associated with the previous work in reconstruction (Zhang et al. in Int J Adv Manuf Technol 2015:1-16, 2015. Comparing with conventional measurement, the proposed method can not only improve the utilization of measurement data from multi-sensor system but also consider the uncertainties of measurement and localization in data merging. Concretely speaking, the low-precision data from non-contact measurement device is used for establishing possible substitute models. The modified Bayesian information (Modi_BIC) criterion based on Bayesian statistics is introduced as the principle to select the model structure. In order to reduce misalignment errors of the selected substitute model, the statistical analysis of Fisher information matrix is applied to determine registration points. Based on this, the uncertainties can be given in the form of variation boundaries. Comparisons with the specified tolerance band determine a set of re-measured points by using a contact measurement device. The high-precision data can be merged with the selected substitute model by means of free form deformation (FFD) technique. The final measurement data is provided in the form of skinning surface that is consistent to the reverse modeling methodology of aero-engine blade. Moreover, some practical examples are given to demonstrate the effectiveness and superiority of the proposed method.

Section: Overview Of the Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient measurement of aero-engine blade considering uncertainties in adaptive machining

Zhang

Tao

2015

“…Owing to the increasing demands to maximize the performance and quality of manufactured blades in the aerospace industry [1], the distortion of blades is controlled to ensure that their precision satisfies the geometric and dimensional requirements [2]. However, blade features such as thin walls, sculptured surfaces, and difficult-to-cut materials cause difficulties in controlling distortion.…”

Section: Introductionmentioning

confidence: 99%

A control process for machining distortion by using an adaptive dual-sphere fixture

Jiang

2016

Blades are affected by clamping, cutting forces, and residual stress, thus resulting in warping and distortion because of the thin wall and free surfaces. In this paper, a new process for the control of machining distortion is proposed to eliminate surface errors by using an adaptive dual-arm fixture. First, some causes of distortion by different machining methods are discussed. Second, an adaptive mechanism with eight degrees of freedom is designed to allow the blade to be clamped under an unstressed state and to enable the release of stress at any time. Thereafter, a dual-sphere fixture is designed on the basis of the adaptive mechanism. Finally, by adopting this process based on the adaptive dual-arm fixture, machining distortion is reduced after releasing stress several times. Experimental results show that the process can eliminate 50 % of surface errors in machining. Therefore, a test blade machined by the proposed process will exhibit improved precision.

“…Although secondary machining regions mostly refer to partial profile and leading/ trailing edge (LE/TE), the current processes such as manual grinding and polishing are not satisfactory in terms of efficiency and reliability. Since each blade undergoes complex deformation within the range of design tolerance in the forming process [2], its nominal computer-aided design (CAD) model cannot be directly used for NC tool path generation. In addition, the repair process of serviced blade faces the similar challenge [3].…”

Section: Introductionmentioning

confidence: 99%

Reverse modeling strategy of aero-engine blade based on design intent

Zhang

Tao

2015

Blade geometry plays an extremely important role in the aerodynamic performance of aero-engine. However, in the process of secondary machining for near-net shape or serviced blade, the deviation between the actual and nominal blades can raise serious problems for NC tool path generation. It is even worse that inappropriate reverse modeling may change the design intent and deteriorate the aerodynamic performance. This paper presents an innovative strategy for reconstructing actual profiles from measured data. Comparing with conventional reverse modeling, the proposed strategy emphasizes functional significance of the known feature information concerned with implicit design intent. The preservation of design intent has three levels by cognition of the feature information. Firstly, the established technique for rigid registration is improved by means of incorporating accuracy feature into localization. Secondly, the parametric design methodology of aero-engine blade profile is introduced into the free-form deformation (FFD) of cross sections to control geometry feature, and finally, it guarantees aerodynamic performance feature. Some practical examples are given to demonstrate the effectiveness and superiority of the strategy.