Papers by Author: Jia Tai Zhang

Abstract: Module partition of Complex product system (CoPS) usually produces a number of schemes, and how to choose the best one amongst the themes is very important. In this research, according to the features of CoPS, the multi-level evaluation indexes are built based on the DFX (design for X) method, which can evaluate the scheme comprehensively. The weight of indexes are obtained with the method of analytical network process. Then, the multi-level grey fuzzy comprehensive evaluation method is proposed to make the well-chosen decision based on the DFX multi-objective evaluation model. The evaluation method are illustrated using the partition schemes of the experiment platform of a bevel gearbox.

Abstract: Aimed at the problem of reading and controlling UG files by OpenGL in VC++ environment, a method of object-oriented programming is proposed. The OpenGL single document, multiple documents and visualization windows are created by using the classified idea in VC++ environment. PRT format data files of UG are converted to DXF format data files. Not only the conversion rate but also the conversion quality of different format data file are ensured by using the intermediate conversion format CGM and the problems of redundancy lines and view missing are prevented. DXF files are converted to 3DS files by 3DS MAX software. Controlling and redrawing of UG files in OpenGL are realized. The Object-oriented method is better than process-oriented program design method on the reliability and operability of procedure. The method has been applied in the virtual CNC milling system and provided a theoretical basis for the development of visualization system.

Abstract: Aiming at the characteristics of optional disassembly problem, disassembly strategy based on bionic disassembly hive model is presented in this study. This method is combined with modular theory to resolve the data explosion which is caused by too many parts in disassembly body for relevant algorithms. Through establishing disassembly hive space model, the judgment of disassembly direction and some other problems are transferred into the evaluation of ant bee groups’ migration routes. The relative disassembly difficulty of the part is defined based on the conception of disassembly ring. And new ideas of obtaining disassembly sequence are introduced to improve the efficiency of getting disassembly programs.

Abstract: From the perspectives of modularization disassembly, the influence of entity structure, function, motion and other factors of product brought to disassembly efficiency is elaborated. A way to improve design facing modularization disassembly is proposed. The time and cost of disassembly are checked by the proposed method through examples. Comparisons of disassembly evaluation before and after improvement are conducted based on the results. The general method to improve design is summarized. In terms of differences of repair probability of key parts in maintenance process, the improvement design criterion is put forward in the method, which improves the maintenance efficiency, reduces the maintenance cost and difficulty of disassembling operation and avoids data explosion of disassembly sequence because of too many parts.

Abstract: The simulation turntable is a high precision and semi-physical simulation installation. In order to meet high precision of turntable, the precision prescribed in all sets of axes of turntable is required during manufacturing process and assembly. Based on assembly process of three-axis simulation turntable, the detachable structure of U frame is designed. Components of the frame are formed by bolted joints. So the strength and stiffness of the U frame with bolted joints must meet initial design requirements, simple and reliable finite element simulation method of bolted joints is applied based on ANSYS software in the paper. The connection of screw threat pair is simulated by nonlinear elastic contact mode, and the preload to bolts is loaded though pretension element of ANSYS software. The numerical analysis is performed to confirm that the detachable structural U frame with bolted joints is satisfied with structural requirement and the strength of U frame is influenced by the pre-tightening force of bolt at the extent.

Abstract: To resolve key technology of parameter optimization of virtual NC milling physical simulation system, a multi-objectives optimized model was set up by non-linear programming theory and resolved by improved parallelism selection genetic algorithm. It was optimized when milling characters are sufficiently considered and machine quality was guaranteed. Sub-population size is decided by weighting each optimized object and calculating adaptation to assure importance of optimized objects and fasten convergence velocity. A kind of software that can optimize milling parameters of virtual NC was developed, and optimized strategy and validity of algorithm are verified which provides technology support for realizing virtual NC milling physical system.

Abstract: Joint modeling of exponentially fitting and least square method was proposed for key technical problems on milling temperature and heat deformation of tool in virtual numerical control (NC) simulation. Mathematic model of surface temperature and its influencing factors based on ball-end mill was established. Correlation coefficients of model are over 0.8, and the errors comparing with the experimental ones are within 10%, which shows that the model meets precision requirement, and fitting effect is good. By this model a mathematical model of the ball-milling cutter’s thermal deformation was established, and the relative error is small by comparing with test values, which proves that this model has high calculation precision and practical meaning. A simulation prediction system of milling temperature and ball-end mill’s heat deformation in virtual NC was developed based on above mentioned models, which can provide theoretical basis for machining error prediction, optimizing milling parameters and improving machining quality.

Abstract: . Modular design technology is one of the ways to realize the product variety. It has been widely used in increasing fields. Module partition which has been the hot spot in and around the world is the key part of modular technology. In this paper, the combination of system clustering and the fuzzy ISODATA algorithm is used to achieve the rough-to-fine division according to the principles of module partition. Finally, the automobile security system has been taken as a case to justify the validity of the method and the result of the division accorded with the function of it.

Abstract: Failure in FMS includes two aspects: equipment breakdown and tool failure of which should be considered in an excellent FMS scheduling system. Most of past scheduling researches have only discussed the former and the analysis of the latter rarely seen in relevant papers. The scheduling system without tool failure processing seems to be not coincident to the actually production in which tool breakdowns are very common. This paper gives a dynamic scheduling simulation model with concern of the two kind failure using Object-Oriented technology and Colored Petri Net (OOCPN). Rescheduling strategy of tool failure is proposed and the simulation analysis is given which shows that our model and principle are effective and adaptable to actual case.

Abstract: Optional disassembly could fulfill the process that parts remove from assembly, which is useful for product maintain, discarding and recycle. Total disassembly planning algorithm can be obtained through proper analysis and evaluation, however that is a difficult process. It is hard to obtain optimal solutions when a huge number of parts are to be removed from an assembly. Exponential explosion during the process of disassembly sequence generation has become a bottleneck for a long time due to over large number of parts included in the product. To solve this problem, an approach based on the modulization is proposed in the paper to generate the disassembly sequence. To partition modules of manufacture equipments, the module identifying method based on multi-rule decision can effectively solve the explosive problem. This method deals with the restrictions and limits of parts before disassembly, hence making disassembly more like the situation of the fact which is limiting the quantity of disassembly combinations, enhancing the efficiency of disassembly and making disassembly much easier.