Papers by Keyword: Thin-Walled Workpiece

Abstract: Thin-walled workpieces are widely used in the aerospace manufacturing industry in order to reduce the weight of structure and improve working efficiency. However, vibration is easy to occur in machining of thin-walled structures due to its low stiffness. Machining vibration will result in lower machining accuracy as well as machining efficiency. In order to reduce the machining vibrations of thin-wall workpieces, commonly used method is to select proper machining parameters according to the chatter stability lobes, which is generated according to the machining system parameters. However, this method requires exact system parameters to be determined, which are always changing in the machining process. In this paper, a special designed fixture with damping materials for the thin-walled workpiece is presented based on the machining vibration control theory, and analysis of the effect of vibration suppressing is obtained through the contrast of vibration tests of milling the thin-walled workpiece on the damping clamp. The damping material is used to consume vibration energy and provide support for thin-walled structure. Machining test was carried out for thin-walled structure machining to validate the effectiveness of the proposed method.

Abstract: Thin-walled workpiece is easy to deform in machining. In order to predict the dimensional error of machined surface of thin-walled workpiece, computer simulation technology is studied, which is called virtual machining process. For the simulation of workpiece deformation, much numerical analysis should be done. Research indicates using FEA (Finite Element Analysis) in each step of simulation process needs too much time to meet the requirements of industrial application. Therefore it is important to decrease the simulation time. In this paper, a new method is proposed to realize rapid analysis of workpiece deflection in virtual machining process, which combines rapid analytical solution method with a few times of accurate FEA, thus greatly decreases the time required for whole simulation. For the simulation, several peripheral milling process models are presented with increasing order of sophistication and accuracy, which can be applied to simulate cutting process with the effect of workpiece deformation caused by cutting force. In the final section, the comparison between simulation results and experiments shows the proposed methods and models can closely predict dimensional error and texture of machined surface of flexible workpiece.

Abstract: Due to the deflection of tool and workpiece induced by cutting force, there is a high complexity associated with the prediction of surface form errors in the peripheral milling process of thin-walled workpieces. And the prediction of surface form errors induced by cutting deflection is the precondition for process optimization and error compensation. This paper proposes a systematic simulation procedure suitable for surface form errors prediction in peripheral milling of low rigid thin-walled workpiece. Some key algorithms with the judgment of contacts between the cutter and the workpiece, the flexible iterative algorithm as well as the tool/workpieces deflection prediction using FE model are developed and presented in detail. Comparisons of the form errors and cutting forces obtained numerically and experimentally confirm the validity of the proposed algorithms and simulation procedure.

Abstract: Thin-walled workpieces have the characteristics to withstand a greater load with less material and they are used in aerospace field widely. SiC_p/Al composite has high strength and stiffness, which meets the requirements of the aerospace workpieces well. The optimization method is studied with grinding stability and material removal rate as constraint conditions in this paper. The processing parameters optimization of a SiCp/Al thin-walled cylinder is analyzed according to stability lobe diagram. The grinding parameters optimization could be achieved by this method and the chatter could be prevented effectively.

Abstract: Particle reinforced aluminium matrix composites could be used in manufacturing of aviation thin-walled workpiece due to its excellent performances, but it is hard to be manufactured. Rotary ultrasonic machining (RUM) is very suitable for machining particle reinforced aluminum matrix composites with moderate or high volume fraction. Chatter appears very easily in machining process of thin-walled workpiece and it can seriously reduce the quality of components. Based on the dynamic characteristics of machining process, a stability analytical model is built. It is analyzed that the process stability of a thin-walled workpiece of SiCp/Al composites reinforced with 45% volume fraction, and the stability lobe diagram is plotted by using MATLAB. According to stability analysis results, a machining experiment is conducted and the test results indicate chatter could be prevented effectively by this method.

Abstract: In order to control chatter in machining of thin-walled workpieces, the dynamic model of milling od thin-walled workpiece is analyzed based on considering the flexibility of the workpiece and the machine. In high speed milling of 2A12 aluminum alloy, the compensation method based on the modification of inertia effect is proposed and accurate cutting force coefficients are obtained. The machining system is divided into “spindle-cutter” and “workpiece-fixture” two subsystems and the modal parameters of two subsystems are acquired via modal analysis experiments. A method for obtaining the stability lobes is presented by considering the relative movement of both subsystems. Finally, the stability lobes for high speed milling of 2A12 thin-walled workpiece are obtained and compared between considering three kind of modal parameters. The results are verified against cutting tests.

Abstract: The metal cutting is a complexly dynamic physical process of thermal-mechanical coupling. It is difficult in analyzing the mechanism of machining deformation with the traditional calculation method. The key simulation technologies of the machining process are analyzed by means of finite element method (FEM), such as material constitutive model, chip separation criterion, tool-chip interaction and friction model, thermal control equation. During finite element simulation of the peripheral milling of the thin-walled workpiece, the contact constraints between the tool and workpiece can be effectively simplified. Thus, the tool and workpiece are considered as rigid and elastic bodies, respectively. In sequence, the unit birth and death technology is used to simulate the material removal in the milling process so that the effect of the workpiece size on machining deformation can be researched accurately. The investigation on the theory and application of the above key technologies can not only analyze and predict the deformation of thin-walled parts, but also optimize process parameters to control the machining deformation.

Abstract: A new method for vibration control of aeronautical thin-walled workpiece in high-speed milling progress using a dynamic vibration absorber is presented. First, the theoretical model of the method is established and studied. Then the effectiveness of this method is testified via the simulation based on FEM. Finally, the feasibility of this method is discussed. The result shows that this method for vibration control of the aeronautic thin-walled workpiece in high-speed milling progress is effective and practical.

Abstract: Because of its low stiffness and intensity structural features, thin-walled parts affected by milling force, easily produce deformation and vibration among processing. In this paper, by optimizing milling parameters, it can be realized to control the size of the dynamic milling force and the milling state. Then it reaches the purpose to decrease workpiece deformation, and makes processing conditions maintain a stable. It not only reduces deformation caused by the vibration, but also makes thin-walled parts errors meet the tolerance requirements.

Abstract: This paper proposes a new efficient iterative algorithm which named flexible iterative algorithm (FIAL) with a general approach suitable for surface form errors prediction in peripheral milling of thin-walled workpiece. First, a FEA-Based model is presented to analyze the surface dimensional errors in peripheral milling of thin-walled workpieces. Then the FIAL is discussed in detail for the procedure of deformation prediction. From FIAL, an iterative scheme for the calculations of tool/workpiece deflections considering the former convergence cutting position are developed，in the scheme a small variable must be included in the calculation of radial cutting depth which never been considered in the literatures before.The proposed approach is validated and proved to be efficient through comparing the obtained numerical results with the test results.