Applied Mechanics and Materials Vol. 159

Abstract: According to the multi-body system theory and geometric topology analysis method, combining the geometric structure and working principle of thread NC grinder, made the kinematics analysis for each parts of NC grinder. And the mathematical model for geometric topology structure of grinding machine system was established; the precision machining equations of NC grinder was deduced. Furthermore, the paper used the coordinate transformation principle of homogeneous to deduce the precision processing equation of NC grinder, all of that was based on the moving relationship of the machine tool, the workpiece and the grinding wheel, and got a kind of method that it can use multiple line grinding wheel to grind small radius, small screw pitch and multiple thread. This method laid a theoretical foundation for NC grinder machine processing which used multi-line grinding wheel to grind threads, and improve the grinding efficiency and precision of multi-line grinding wheel; in addition, this method has obtained good effect in grinding thread production.

Abstract: Machining distortion analysis and control are the kernel problem in manufacturing industry recently. This paper take face milling as research object, a finite element model for 3D milling process is set up based on some key techniques including cutter feed trajectories representations, cutter tooth-workpiece engagement model etc; Then the optimum LS-SVM model which can express the transitive relationship between cutting parameters and distortion error is set up; The cutting parameters optimization model based on controlling the machining distortion is founded by seeing the optimum LS-SVM model as the main objective function, meanwhile, an effective multi-objective optimization algorithm is proposed by coupling particle swarm algorithm and gray relevancy analysis, this algorithm can change the multi-objective optimization problem into optimizing the gray relevancy value effectively. As an example, the feasibility of proposed machining distortion controlling approach is verified.

Abstract: Modal parameters for LG51SH broaching machine from operational responses are studied to examine the dynamic properties of mechanical structure. The operational modal is analyzed using PolyMAX method with responsive data of key point in broaching machine, which is excited in practical broaching operation and tested by LMS SCADAIII-105 system. The identified steady state modal, representative modal shape, modal damping ratio and natural frequency in broaching are presented. The test and analysis result shows that there are natural frequency of 38Hz and 192Hz, which are close to multiple of the fundamental frequency of cutting force in broaching, 6Hz, therefore, reasonable cutting velocity should be adopted to void producing fundamental frequency of cutting force in broaching.

Abstract: Inconel 718 is a high nickel content super alloy having high strength at elevated temperatures and resistance to oxidation and corrosion. EDM process has many advantages over traditional manufacturing process during the machining of inconel 718. In this study experiments were conducted based on the L16 orthogonal array on inconel 718 material using tungsten-carbide (W-C) electrode tool material with kerosene as a dielectric fluid to determine the optimum EDM parameters along with circle(C), square(S), rectangle(R) and triangle (T) tool geometry which contribute to material removal rate (MRR), tool wear rate (TWR) &surface roughness (SR) in machining of inconel 718. Data were optimized using Desirability approach technique. Experimental results show that the current and pulse on time are most influencing parameters that are directly proportional to MRR and inversely proportional to TWR, SR. The rectangle tool geometry gave better results compared to other geometry

Abstract: The improved adaptive genetic algorithm has been presented to overcome the premature convergence problem of traditional genetic algorithm and obtain the genetic operator having adaptability at any time. Then, the location in the working space has been setted by the serial number method, and the mathematical model has been established for the picking operation of mobile robot. Finally, the sine type adaptive genetic algorithm has been adopted to improve the initial path and get the optimal solution. In addition, a simulation has been conducted by the Matlab Genetic Algorithms Box to show that this algorithm is more quickly and efficiently for the path optimization of mobile robot.

Abstract: A reverse engineering based point cloud data acquisition method is addressed. The most critical part of reverse engineering (RE) is data acquisition of the digital model, the quality of design is determined by point cloud data acquisition, which is related to the accuracy of design. The measurement of relative position of different parts has been a difficulty of data acquisition. In this paper, the ATOS optical scanner was used as an example to illustrate the principle of three-dimensional scanner, the positioning methods and procedure of point cloud processing. A case study of point cloud data acquisition of car body was used to illustrate three-point positioning principle, which improves the accuracy of measurement compare with traditional method.

Abstract: In this study, ZrO2-7wt.%Y2O3 thermal barrier coatings (TBCs) were prepared on TiAl base intermetallic alloy substrates by plasma spraying process. After that, the plasma-sprayed TBCs were laser remelted using a CO2 laser. Influences of laser remelting on the microstructure and solid particle erosion characterization of the coatings were researched. Meanwhile, the erosion damage modes of the two types of TBCs were discussed. The results show that the as-sprayed TBC has a typical lamellar stacking characteristic. The lamellar defect of the plasma-sprayed coating is erased, and the compactness of the coating is improved significantly after laser remelting. The laser-remelted coating consists of column-like crystals along the direction of the heat current. The laser-remelted coating had better erosion resistance than the as-sprayed coating. Owing to the limited bonding at the interfaces between lamellar, the spalling of the sprayed splats from the lamellar interface is mainly attributed to the erosion failure of the as-sprayed coating. In addition, crushing of brittle ceramic coating is also responsible for the erosion damage of the plasma-sprayed TBC. In contrast, cracking occurs within region near the surface of the laser-remelted layer and that erosion occurs mainly by removal of these small blocks. Moreover, the laser-remelted has evident mciro-cutting marks and shows some ductile erosion characteristic.

Abstract: Abstract: A kind of automatic polishing equipment for free surface of dies is designed, which is fixed on the backbone of numerical control machine. Processing parameters optimization are gotten by the orthogonal analysis method based on experiment data and surface roughness is about 1.0μm, which provides good basis of practical research and application of accurate working for free surface of dies.

Abstract: In this paper, the machining properties (including planning, sanding, drilling, shaping, mortising and crosscutting) of Magnoliaceae glanca Blume, compared with Castanopsis hystrix, were tested. Their properties were conducted according to the criteria ASTM D1666-87 and the test on crosscutting was referred to the method established by New Zealand Forest Research Institute. The results show as follow: The machining properties of Magnoliaceae glanca Blume and Castanopsis hystrix in the planning, sanding, boring, shaping and crosscutting all show excellent, but the mortising property, a bit poor, shows good. The comprehensive properties of Magnoliaceae glanca Blume are better than Castanopsis hystrix.

Abstract: In this paper, the planning and sanding properties of Toona sinensis, compared with Castanopsis hystrix, were tested. The properties were conducted according to the criteria ASTM D1666-87. The results show as follow: in the evaluation system for full marks 5 points, the planning marks of Toona sinensis and Castanopsis hystrix was separately 4.4 points and 4.7 points, and the sanding marks was separately 4.7 points and 4.3 points, slightly different; the planning and sanding properties of Toona sinensis and Castanopsis hystrix all show excellent; feeding speed had remarkable influence on the planning properties of Toona sinensis and Castanopsis hystrix; cutting thickness had different influence on the planning properties of two kinds of woods; the wood quality had important influence on the sanding property.