Materials Science Forum Vols. 532-533

Abstract: To alleviate the feed fluctuation and maintain a smooth feed in five-axis machining, this paper takes the following two constraints into account: (1) the machining dynamics, including the constraints of power, velocity and acceleration represented by upper bounds for each axis (2) the contour constraints of the tool path, including the linear distance of the segment and sharp corner at the segment junctions. With the analysis of these constraints, the optimal feed is derived and the corresponding adjusted interpolation algorithm is presented such that a smooth motion during the machining can be obtained. The presented algorithm is demonstrated by the simulation result.

Abstract: Turbine blade is one of the critical parts of the aero engine and usually has complex structures. The main purpose of this paper is to present a virtual cutting based method for aero engine turbine blade reverse modeling from its cone beam computed tomography (CBCT) images. Based on the turbine blade CBCT images, an improved Marching Cube algorithm was used to construct a 3D mesh model of the turbine blade. Then, cutting tools of parallel planes, concentric cylinders, concentric cones or revolved free form surfaces were used to cut the turbine blade mesh model to get the profile curves. After the profile curves were constructed by curve fitting and joining, the lofting geometric modeling technique was used to generate the turbine blade airfoil surface working in parallel flow, cylindrical flow, conical flow and revolved free form flow respectively. A set of computer simulating turbine blade CBCT images (512×512×512) was used to test the presented method and the testing results showed that the method was feasible and convenient.

Abstract: Reported in the paper is an elastic-plastic contact model developed to analyze the contact performance characteristics of materials with gradient yield strength. Plastic yielding and the strain-hardening properties of the materials are taken into account. The finite element method, the initial stiffness method, and a mathematical programming technique are utilized to solve the contact model. The von Mises yield criterion is used to determine the inception of plastic deformation. Results indicate that nitrided material with appropriate gradient of yield strength may greatly alter the distributions of contact stress, contact pressure as compared with untreated material in contact. The effects of different yield strength variation path of material on von Mises stress distributions are numerically investigated and discussed.

Abstract: In traditional NC curve grinding, the grinding wheel’s rotary surface is generally not on the grinding point’s normal direction, which will bring the distortion of grinding wheel and decrease the machining precision. This paper presents a new technology, which is called the non-interference normal tracking for NC curve grinding process. By controlling the worktable to rotate in the x-y plane, the superposition between the rotary surface of the grinding wheel and the normal vector of the workpiece’s contour is realized, and the interference between the wheel’s body and the workpiece could be avoided at the same time. A mathematic model is established and an algorithm to calculate the worktable’s rotary angle is proposed. Finally, the algorithm is applied in a new-type digital curve grinder successfully. The results show that the method is reliable and effective.

Abstract: A novel method is introduced. Simplify Stewart platform by using of group technology. Six legs 6-6 Stewart Platform is transformed into three group legs Stewart platform by way of geometrical knowledge and numerical analysis. Make emulational program of Matlab 6.5 to validate the method of direct kinematics. Velocity and precision of computing are advanced by repeatedly optimizing of method. The method is scientific and novel.

Abstract: In this paper, the strength and deformation of an elastic orientating component (sleeve) were analyzed by Finite Element Method (FEM). The highest stress of the part and the relationship between the dimension and deformation were found. The position under the critical situation was obtained. The optimal dimension of the sleeve was given.

Abstract: Based on the research of the functions of ANN-based cold extrusion process design system, genetic algorithm (GA) is proposed to optimize the topology and parameters of artificial neural networks (ANN), in order to improve the running efficiency of the networks. The binary encoding approach is implemented to represent the GA chromosome. The code string or the chromosome was divided into three parts: the first part is the binary code of the cold extruded part; the second part is the binary code of the topology and parameters of ANN; the last is the binary code of the semi-cold-extruded-part or the billet. The 1/F(X) function is selected as the fitness function in GA, where, X represents the binary code of the cold extruded part, F(X) represents the error between the real outputs of ANN and the desired results; the biased roulette wheel selection method is used for selecting operation in this paper; two-point crossover and one-point mutation are selected for these two types of genetic operations. Finally, the typical cold extruded part is used for verification as an example by using the optimized ANN, the result shows that ANN optimized by GA has efficiency and validity in the cold extrusion process design system.

Abstract: Research on innovative methods for Conceptual Design of Control Strategies (CDCS) is of great theoretical and engineering meaning. In this paper, TRIZ-aided innovation in CDCS was proposed. At first, a systematic approach to build a new theory of inventive problem solving specialized for control strategies (TRIZ-CS) was proposed with its systemic structure was given. Then the Block-Signal analysis model (B-S analysis model) was proposed based on Su-Field analysis model in TRIZ with its symbol system and application procedure. Finally four examples were given to show the rationality of TRIZ-aided innovation in CDCS and effectiveness of B-S analysis model. The examples show that TRIZ-aided innovation is a systematic, effective and practical innovative methodology for CDCS.

Abstract: A real-time model of two-direction grinding force for external plunge grinding process has been built based on the research of grinding system dynamics equation. The two-direction grinding force can be measured on-line by a force cell sensor developed in this paper. And the grinding depth and grinding force, which depend on grinding time, were dynamic simulated by computer simulation. The experimental results are in good agreement with the simulation results, proved the real-time model’s exactitude. The real-time models showed in this paper not only can predict and evaluate grinding behave and quality, but also provide the precondition for grinding optimum, intelligential control, and virtual grinding research etc.

Abstract: In the advanced manufacturing technology, how to integrate CAD/CAE software has become a very important research issue. After analyzing the function framework of collaborative design and simulation platform, the management model of collaborative design and simulation platform for numerical engineering is proposed in this paper. Moreover, workflow management technology, collaborative running management, collaborative development model database, database management, and Win32 API message interception technology are studied in detail. An object-oriented software integration method is presented. The method is divided into three lays: interface integration, data integration, and operation integration. A C/S structural prototyping system is developed by using C# and XML under .NET development environment. The system can support customizing engineering design and simulation task, which integrates various design and simulation tools, including some self-developed application tools.