Papers by Author: Zhi Feng Liu

Abstract: An association between the components structure is studied in the product design in this paper, and some ideas of improving the development of new product and the decision-making efficiency of its selection scheme has been proposed according to the ideas of the process modeling and global design. Then, the hierarchical principle of feedback mechanisms is introduced to construct a new process modeling method, and the descriptive power of object-oriented process model and the design flexibility of new product are improved. The method has been applied to construct rapidly the automobile coating production line successfully.

Abstract: In this thesis, a new identification method for joint stiffness and damping has been developed by using the substructure synthesis method and finite element modeling. The substructure synthesis method is stated firstly, according to the substructures are connected by joints and the equilibrium and compatibility conditions at the joints have to be fulfilled, establishing identification equation through completely frequency response function. Then, finite element model is established, and update this model, make use of the update model to replace the experimental model, using an accurate finite element model to obtain the required data. In order to ensure the stability of the numerical calculation, translate inconsistent equation into the general solution through the principle of least squares, besides the introduction of the concept of weighted, makes the measured data can be fully utilized. Finally, the method is applied to a simulated example and good agreement is found between identified and true parameters.

Abstract: Test paper problem is a typical multi-constrained objective optimization problem. By using genetic algorithm, this paper analyzes the initial population generation, the chromosome coding and its genetic manipulation, control parameters. Solving that by natural-coded genetic algorithm, improves test paper success rate and convergence rate. This genetic algorithm is applied successfully on NHibernate architecture, and developed "automatic test paper" Online Examination system.

Abstract: The heavy load deflection angle milling head is an important functional component of 5-axis CNC machine tool, which is used for large and complex free-form surface processing. The characteristics of this kind of milling head are implementing multiple degrees of freedom motion with revolution and deflection angle simultaneously. Obtaining milling head dynamic and static characteristics is a pre-requisite problem to resolve for the development and research of heavy load deflection angle milling head independently. Dynamic characteristics are obtained through combination with CAE (Computer-aided Engineering) technique and experiment validation. For CAE analysis, the main parts of milling head are glued together considering milling head operating at a specific position. Experimental validation is carried through with initial fixing constraint style, which validates the correctness of CAE technique. Experimental and CAE analysis results are compared and analyzed. Therefore, exact dynamic characteristics of milling head and unsubstantial segments and its influence factors are gotten. Static characteristic is obtained considering milling head operating in different posture by CAE technique. The analytical method of three points at half of cutter are loaded is introduced. Calculated results indicate that the deformation of tool tip is the largest when milling head operating in 45° posture, which corresponds with the deformation situation of the milling head operating in workshop. The analytical results of dynamic and static characteristics of milling head provide theoretical and experimental support for structure optimization and improving of heavy load deflection angle milling head.

Abstract: The stiffness and damping of mechanical joint are modeled by the zero thickness joint interfaces theory. The method is applied to analyze the dynamic characteristic of the gantry frame in a five axis turning-milling compound CNC machine tool. The model test is carried out in the gantry frame, and the maximum error of the first sixth mode is 5.63%. The experimental and analysis result show the zeros thickness joint element can provide an effective method to model the machine joint and predict the dynamic characteristic of the assembled structure.

Abstract: This paper summarizes and analyzes several construction methods of a list of common materials, proposes a new type of path-based BOM construction methods, improve BOM arithmetic to achieve BOM traversal algorithm. The BOM structure and its traversal algorithm are applied to data management platform of heavy-duty machine tool, which improve the operational efficiency of data management platform.

Abstract: Heavy duty deflection angle milling head is the core functional unit of heavy-duty gantry CNC machine tools. Stiffness of swing chain system is one of the important factors that determines accuracy of heavy duty deflection angle milling head. In order to improve dynamic performance and mechanical precision, the gear pair and support system of the swing chain are studied in the paper. Based on the deformation compatibility condition and the superposition theorem, the torsional deformation and stiffness of each part are analyzed, and considered the deformation of workpieces and supporting system and the interaction of them. The vulnerable segment is found out in the paper, which is valuable to amend and improve the design of milling head. At last, the curves of the relation between the swing chain stiffness and the gear parameters and bearing preload are charted, which provide the theory and technical support for digital design, optimization of the milling head and the basis for the similar driving system stiffness calculation.

Abstract: According to the characteristic which is more and difficult to determine about the automotive panel forming factors, based on the dynamic explicit method, taking the typical automobile front fender for example, do the simulation analysis by using of DYNAFORM. On the premise of taking springback factors into account, analog the best stamping process parameters has been optimized from the analysis results after simulation such as sheet metal forming limited drawing(FLD)and sheet metal thinning drawing.