Figure - available from: The International Journal of Advanced Manufacturing Technology
This content is subject to copyright. Terms and conditions apply.
Source publication
The aero-engine blades are mostly thin-walled with complex structures, which are prone to flutter, deformation during processing. All these characteristics make it difficult to machine the blade qualified. In order to improve the precision and efficiency of blades machining, a self-adaptive clamp machining process method is proposed in this paper....
Citations
... Good potential for structural optimization has a transformable pin array fixture system, comprised of reconfigurable pin array fixtures, that locates and holds parts for assembly and supports parts of different shapes adaptably [18]. Also, dedicated self-adaptive fixtures are available in airplane turbine production [19,20]. ...
... The improved flexible fixture was investigated using numerical simulation of the stress-strain state in the Static Structural module of the ANSYS ver. 19 Workbench Software (ANSYS, Inc., Canonsburg, PA, USA). At the same time, the deflection of the movement of the machined surfaces of the part (marked in red in Figure 3) relative to their initial position will also be evaluated. ...
In the conditions of the increase in the range of products in the automobile and aircraft industry, there is a tendency to increase the scope of application of flexible fixtures. Thus, in the current article, it was proposed to consider a new concept of a flexible fixture for location parts of a complex shape. The stress and deflection of the steering knuckle elements were calculated using finite element modeling. During the experiment on the static loading, the deflection of the steering knuckle elements was measured, and the results of finite element modeling were validated. It was determined that the stiffness of the proposed flexible fixture ensures compliance with the tolerances of the mutual location of the surfaces of the part, making it reasonable for feature research the novel flexible fixture design during milling.
... This fixture effectively reduces clamping force and machining errors. Hao et al. [99] designed an improved adaptive auxiliary fixture to address the issue of cutting chatter during the machining of aircraft engine blades, which effectively reduces the problem of cutting chatter. Wu et al. [100] analyzed the adaptive machining technology and designed a new type of adaptive fixture. ...
Thin-walled parts processed by five-axis CNC machine tools are widely used in aerospace and other fields due to their excellent performance. However, due to the weak rigidity of thin-walled parts, they are prone to deformation during milling, which poses great difficulties for efficient and precise machining of thin-walled parts. This paper introduces the classification and corresponding machining methods of thin-walled parts. By analyzing the causes and evolution mechanisms of errors in the machining process of thin-walled parts, and combining modeling methods with factors such as milling force, residual stress, and cutting chatter, the current research status of domestic and foreign scholars on deformation factors is summarized. At the same time, two deformation control methods, adaptive machining and error compensation, were introduced. Finally, the overall research status of thin-walled parts machining was summarized, and prospects for efficient and precise machining of thin-walled parts were proposed based on actual machining conditions.
... Ratchev et al. [7] and Richter-Trummer et al. [8] predicted the machining deformation of the blade by analyzing the force interaction and measuring the residual stress, respectively, to select the best machining parameters to ensure the machining accuracy and shape of the blade by reducing the deflection deformation of the parts. In view of using external equipment, a special flexible clamping is often adopted, for example, Hao et al. [9] and Sanz-Calle et al. [10] adopted the self-adaptive auxiliary fixture of lowmelting-point alloy which have simple structures and the semi-active tune-able clamping table (TCT) based on mode tuning to improve the local stiffness of the workpiece during machining. The first type of method is widely used at present. ...
Existing works in the optimization of five-axis machining mainly focus on the efficiency, precision, or dynamic performance of the machine tools, while the performance of other equipment which assists the machining process has not been considered. This paper takes the robot assisted supporting machining of thin-walled blades as the research objective, and proposes an axial-sensitivity-reduction based five-axis toolpath re-scheduling method for facilitating the collaborative support machining with a machine-tool and a robot. The input of the method is lenient, merely including the original toolpath and the workpiece point-cloud model. The output of the method is the re-scheduled toolpath which requires lower motion ability of the assisted support equipment. This is realized by the following approaches. First, an axial sensitivity concept is defined, which quantificationally reflects the influence extent of the machine-tool axis motion on the assisted supporter motion, thus the most sensitive axis which affects the assisted process maximally can be identified. Then, an optimal-partition dual-domain-assisted-fitting method is provided to reconstruct the parameterized geometrical model of blades according to the point-cloud model, thus the multi-value property of the blades which troubles the surface construction is solved. After that, a sensitive-axis-calming bidirectional-tangent-bug-searching method is proposed to re-schedule the toolpath of five-axis machining, thus reducing the sensitivity of the most-sensitive axis. The whole method is universal, because a general cutter model is used and the cutter-contact point keeps invariant after re-scheduling. The correctness and effectiveness of the proposed method are verified by illustration machining tests of a steam turbine blade using an AB-type five-axis machine tool.
... More and more thin-walled complex structural parts are used in the structure of aerospace products in order to meet the demanding requirements of aircraft, spacecraft, and precision instruments on the performance and reliability of parts, and the precision requirements for such thin-walled structural parts are also rising [2]. Massive thin-walled structural components are increasingly used in the aerospace industry because they may effectively reduce the number of parts, drastically lower production costs, and well meet the objectives of overall structural lightweight design [3,4]. The requirements for multi-species and multi-process precision manufacturing necessitate numerous iterations of testing, alignment, positioning, machining, repairs, and reworks. ...
In order to realize the high efficiency and precision clamping of large workpieces with several processes and multiple species processing, the distribution number and position of the zero point clamping unit in the flexible quick-change process system for big thin-walled cylindrical structural parts are presented. The error model of the flexible quick-change process system is established by the Monte Carlo method, which is used to optimize the system structure design. The error variation of the flexible quick-change process system under the action of transposition and extreme working conditions such as cutting force is revealed, and further analysis on the sensitivity of the workpiece’s global displacement error and global attitude error to each error source is carried out. After the optimization, a high-quality, cost-effective, flexible quick-change clamping system is created. The three-coordinate measurement experiment is used to test the functionality and accuracy of the flexible quick-change process system. A significantly improved level of the system’s repetitive positioning accuracy (less than 0.01 mm) is detected. Importantly, the flexible quick-change system obtained by the combinatorial optimal design method has been successfully applied to the production of aerospace components with improved quality and efficiency.
... Hao and Yang [5] analysed the traditional machining process and designed a self-adaptive auxiliary fixture composed of low-melting-point alloy which improved both precision and efficiency in blade machining. Jiang et al. [6] proposed flexible clamping method using a mechanical-magnetorheological fluid composite and studied the coupling relations between magnetic field intensity, thickness and position of the workpiece. ...
The aero-engine blade is typically a thin-walled part with poor rigidity and a complex structure. This causes aero-engine blades to be susceptible to flutter and deformation during the machining processing, leading to the dimensional and positional accuracy outside the stipulated tolerance values. With the aim of improving the machining precision of the blades, the conventional blade processing methods were analysed in this study. Based on the analysis, a novel deformation control method named reverse segment machining method was proposed. Additionally, a stress-free auxiliary fixture was designed to improve the stiffness of thin-walled parts. Finally, an experiment was conducted to study the effectiveness of the developed reverse segment method and the stress-free auxiliary fixture in comparison to the forward machining methods. The results show that they can significantly improve machining precision.
... As the core component of aero-engine, the quality of rotor blade directly determines the performance [1] of aero-engine. Along with the rapid development of aerospace industry in recent years, the light weight and high performance of the material under the action of gas working fluid through high distortion and thin-walled blade structure has gradually become the development goal of the new generation aeroengine [2][3], and the complex shaped structure products with this new special alloy material have the poor tool accessibility, serious tool loss and easy deformation of blade profile in NC milling technology [4]; and the thermal re-casting layer and the heat affected zone after EDM will interfere with the forming quality of the key parts of the blade surface [5]. While electrochemical machining (ECM), as a non-contact electrochemical etching technology, can solve the problems of traditional NC milling by virtue of its advantages of not limited by the properties of workpiece materials, no loss of tool cathode and high machining efficiency [6], and electrochemical machining uses high-speed electrolyte to replace EDM with high-temperature breakdown discharge melting by electrochemical etching, thus avoiding the influence of hot casting layer and heat affected zone on molding quality to obtain excellent surface [7]. ...
... The value should be the sum of dynamic pressure, viscous friction force and outlet back pressure, so the input pressure corresponding to the inlet velocity is obtained from the Bernoulli equation of the actual fluid as shown in the Table 1. (4) In above formula, A a and B a are the flow parameters of the gap inlet and outlet, respectively; and H is the head loss of the fluid per unit weight. 15 1.476 0.2 ...
... According to Fig. 9(d), with the increase of inlet pressure, the flow rate in the machining gap increases gradually, and when the inlet pressure PA≥2. 4 MPa, the electrolyte flow rate of the machining gap meets the turbulence condition, and the electrolyte velocity increases along the gap flow, which is beneficial to the discharge of electrolyte products and bubbles. Therefore, the inlet pressure should be more than 2.4 MPa, but the excessive electrolyte flow rate may cause unstable effects such as cathodic vibration during processing, so the inlet pressure PA=2.4 MPa. is selected, which combines the maximum value of the pressure pump of the machine tool at the same time. ...
With the rapid development of aerospace industry in recent years, the use of aero-rotor engine blades with new special alloy materials and high distortion and thin-walled structure has been paid more and more attention. Aiming at the problems of poor tool accessibility, serious tool loss and easy deformation of blade profile in NC milling technology, electrochemical machining can realize the processing of complex special structure products with advanced materials by means of non-contact electrochemical etching process. However, in the process of electrochemical etching, the flow channel structure of electrochemical machining affects the stability of the distribution of electrochemical etching characteristics in various parts of the machining surface and ultimately acts on the forming quality by controlling the liquid phase mass transfer process in the machining gap. Therefore, reasonable design and optimization of the flow channel is of great significance in the process of electrochemical machining. In this paper, based on the existing traditional vertical single-axis feed machining mode and combined with the traditional side flow processing blade flow characteristics, innovatively proposed two kinds of electrolyte flow schemes under the vertical machining mode; Then, based on the above two flow channel structures and the energy loss characteristics of viscous fluid during liquid phase mass transfer, a mathematical model of liquid phase mass transfer flow field is established, which combines the viscosity loss characteristics of electrolyte, and by introducing a optimized flow channel structure that combined with the characteristics of positive flow and side flow and adjusting the parameters of electrolyte inlet / outlet, the optimal design channel structure and uniform flow field of aero-rotor blades are realized. Finally, the accuracy and rationality of the proposed scheme are verified by electrochemical machining verification test, which lays a research foundation and guarantee for the feasibility and accuracy of vertical electrochemical machining machine tool in aero-rotor blades.
The complicated thin-walled components with asymmetric structure are extensively used in aerospace fields. The material of these parts is hard-to-machining (such as titanium alloy and superalloy) and the machining induced residual stress (MIRS) is inevitable in each cutting process. The component is deformed easily after the MIRS is rebalanced, which has become one of the most important challenges for the manufacturing of these parts. To overcome this problem, a deformation control method for the asymmetric thin-walled component by optimizing the machining parameters of the finishing process is proposed, which is aimed at adjusting the distribution of MIRS to make the MIRS tends to self-balancing. Firstly, the deformations of two typical thin-walled components, the thin-walled plate and the circular section plate, that caused by the symmetrically distributed MIRS are discussed in detail. The influence of the component structure on the deformation is revealed. Subsequently, the component is divided into different sub-regions and the optimization algorithm, includes the objective function and constraint, is established to adjust the feed rate of each sub-region. To achieve the optimization, the mapping relationship between the deformation and the feed rate is established by combining the machining experiments and finite element method. And then, the method of adjusting the distribution of the MIRS based on the mapping relationship is presented, using which the component is divided into several sub-regions and the feed rate of each sub-region is optimized. Finally, two group machining experiments on the complex thin-walled blade are carried out. Experimental results illustrate that the proposed method can reduce the machining deformation obviously.
Titanium and its alloy are widely used for aeroengine blades. Due to a severe working environment, various damage such as mechanical fatigue and cracks can be found on the blade. The damaged blades are usually repaired for low in-service cost. In this study, laser cladding of the pure titanium on the Ti-6Al-4V (Ti-TC4) with different laser powers and scanning speeds was conducted to simulate the repair of aeroengine blades. In addition to the experimental investigations, coupled thermo-mechanical finite element (FE) analysis was performed to obtain the temperature and stress fields. The penetration depths of the substrate and uniaxial stress states were subsequently determined. Temperature measurements with thermocouples were also carried out to validate the numerical results. The FE simulations indicate that the uniaxial compressive stresses have been developed in the coatings during the solidification process. Besides, good metallurgical bonding between coatings and substrate is expected to be formed with high laser power and low scanning velocity.
