Advanced Materials Research Vol. 820

Abstract: Incomplete fusion and incomplete penetration are two types of damage serious welding defects. These two kinds of defects have the similarity in the features in X-ray imaging. Identifying the two kinds of defects automatically and accurately can improve the welding technology and improve the quality of welding effectively. The causes of defects and features of X-ray images are described in the paper. The welding defects calssification method based on multi-weights neural network is put forward in the paper. The multi-weights neural network based on graphic geometry theory is introduced, which uses the geometrical shape in high dimensional space to cover the same class defect samples via constructing multi-weights neural network. The experimental results proved the effectiveness of the algorithm.

Abstract: Titanium is a difficult-to-machine material due to its low heat conductivity and high chemical reactivity. It creates high tool wear and causes low machining efficiency. The strong relationship cutting forces between and tool wear and surface integrity of work piece makes it necessary to study the effect of dynamic cutting force on cutting tools to analyse the wear propagation and tool life. This paper investigates the tool wear on Polycrystalline Diamond (PCD) cutters in milling Ti-6Al-4V and analyses workpiece surface quality. Based on the experimental results of slot milling, cutting parameters that yields best surface finish were found.

Abstract: In this paper, the fracture analysis model about the penetrator embedding pre-perforated steel plate vertically is set up. The threshold target impact velocity expression (if the penetrators fracture failure occurs) is obtained. In addition, the influence of the penetrators material parameters on the fracture failure, that is, the threshold target impact velocity, are listed and analyzed, such parameters including materials yield stress, tangent modulus, density and failure strain. The results show that the threshold velocity increases along with the material yield stress, tangent modulus and failure strain, inversely along with the material density. This study would provide strong theoretical and engineering basis for the penetrator design and analysis.

Abstract: Assembly stress exists in mechanical equipment and instrumentation widely. Especially for precision mechanical systems, assembly stress may influence the system accuracy and performance. In this paper, taking form error and assembly force into account, the assembly stress and deformation were studied. By employing numerical simulation technology, the contact state of the part combining surface and additional deformational error were obtained, and an experiment was performed to verify the simulation calculation.

Abstract: In this paper, a combined error model for thermal error compensation of machine tools is presented. Through the analysis of thermal error data of machine spindle at different temperatures, the error variation law is obtained. Experiments on the axial directional spindle deformation on a CNC machine center are conducted to build and validate the proposed models. The experimental validations show that the thermal errors of the machine tool are reduced effectively after applying the error compensation approach. The combined error model performs better than the traditional time series and neural network model in terms of prediction accuracy and robustness, which means that the new model is more suitable for complex working conditions in industrial applications.

Abstract: We expound the finite element simulation and the key points of metal turning by the material properties of the stem in this paper, and select the proper material constitutive equation, then use the adaptive meshing technique, and then finite element modeling was carried out on the valve stem in the professional finite element software Advantedge FEM. The optimization scheme we designed of finite element simulation for the valve stem through the finite element software Advantedge FEM, and we research the influence of the amount of feed and speed cutting process about the cutting force and the cutting temperature.

Abstract: Milling forces simulation is a critical part in the NC processing simulation system, unstable milling forces not only affect tool life, but also can reduce the surface machining quality. Based on the existing milling forces model of ball end mill, this paper establishes a milling forces simulation system which makes seamless integration of geometric simulation and physics simulation come true on UG platform with Matlab and VC++ mixed programming technique.

Abstract: The paper established the mathematic model with the help of computer to analyze the impact of electromagnetic field strength in metallic mineral separation. And then using Finite Element Method of electromagnetic partial differential equations solved the model. The relationship between current density and magnetic field strength was obtained. Finally, analysis results were applied to the actual study for the dry magnetic separation equipment and research results demonstrated the feasibility of this approach.

Abstract: The characteristics of dynamic and static component of the cutting force signal were analyzed when the coated tool was used to cut gray cast iron. It is found that the whole and local of dynamic cutting force signal has self-similarity. Then the dynamic fractal dimension D was extracted by means of fractal theory, and the feature quantity M was extracted from the static cutting force signal. Research shows that the dynamic fractal dimension D of cutting force signal and static characteristic quantity M are varied with the cutting time. Their varying laws can be used to monitor the wear condition of coated tool effectively.

Abstract: To explore the influence of the water vapor cooling conditions on grinding temperature field of titanium alloy TC4 material, ANSYS simulation and test methods are adopted in this paper. Simulation and experimental studies show that: water vapor as coolant can reduce the surface temperature of the workpiece quickly by changing the wheel speed, workpiece speed and cutting depth; Water vapor cooling can control the grinding zone temperature below 400 °C on certain conditions, and compared with dry grinding it can reduce more than 50%; The grinding zone temperature can significantly be reduced by optimizing the grinding process parameters and improving the quality of the machined surface.