Papers by Author: Mei Fa Huang

Abstract: Assembly is an important part in production and development of complex products. Flexible assembly retrieval is one of the key issues to find the reusable model. The main objective of this paper is to extend the model of ontology-based assembly design for model reuse. Firstly, we propose a representation of assembly structural data including topological structure, assembly semantics, and geometrical information. Secondly, we enrich assembly design (AsD) ontology for knowledge captured and shared in Web Ontology Language 2 Description Logic (OWL 2 DL) and Semantic Web Rule Language (SWRL). And then, we define the matching strategies and similarity assessment for two matched models. Finally, we illustrate the validity of assembly design representation for model reuse through experiments.

Abstract: A/C axes bi-rotary milling head is an important functional component in gantry type five-axis CNC machine tool. The static characteristics affect directly the machining accuracy of machine tool. The paper investigates the static stiffness of A/C axes bi-rotary milling head in gantry type five-axis CNC machine tool XK2320-5X developed by a domestic company. Because this product developed depend on the experience of designers, the machining accuracy of A/C axes bi-rotary milling head of primitive XK2320-5X type cannot meet the accuracy requirement under actual working conditions. On the basis of structure design, the static stiffness analysis of the milling head under two working conditions is carried out using finite element method. The deformations of the main mechanical parts in the milling head are obtained. The analysis results indicate that the static stiffness in direction X is the weakest of the milling head and the milling head shell is the most important factor of deformation. The work done provides foundation for further structure design and machining accuracy improvement of A/C axes bi-rotary milling head.

Abstract: Led die bonder used for bond lead frame and chip is one of the key equipment of led production line. The swing-arm is an important component of led die bonder and its dynamic characteristics will directly affect the piece accuracy. At present, the accuracy and efficiency of led die bonder are limited because of the vibration of the swing-arm. In solving this problem, a three-dimensional finite-element model for swing-arm is built to provide analytical frequencies and vibration modes. Then the modal distribution and vibration mode shapes for swing-arm are obtained after analyzing the modal by ansys10.0. Finally the dynamics effects of this structure by modal frequency and vibration mode are analyzed. The modal analysis of structural would provide the reference to dynamics analysis and structural optimization for swing-arm in practical use.

Abstract: A tolerance synthesis model is established based on degree of freedom of geometric variations of features in this paper. The method allows a designer to analyze the relationship between geometric variations of features of a part and functional requirement of assembly (FRA). Firstly, tolerance is modeled with DOFs of geometric variations of features and the tolerance zone is expressed with six kinematic DOFs in three-dimensional (3D) space. Secondly, the stack-up of geometric variations of features is formulated as explicit tolerance analysis equations using kinematical coordinate systems associated with each feature. To express mathematically the relationship between given FRA values and the corresponding DOFs of geometric variations of features, the reverse synthesis equations are obtained using a matrix inversion scheme of the tolerance analysis equations. Finally, a case study is used to illustrate the proposed method.

Abstract: To accelerate the development of new product, one important method is to use the information of the existed products. In this paper, Fuzzy C-Means clustering method (FCM) is proposed to retrieve the desired model in the given model database. In the retrieval process, first, the shape distribution histograms of the model are established and transformed into the proper format of FCM. Then, the shape distribution histograms of the model are served as inputs of FCM and classified into several groups by this algorithm. Last, all the models that belong to the classification of the query model are returned as the retrieval results. To validate the proposed method, a case study is presented. The results show that the result of proposed method is better than that of Shape Distribution. Thus, this method is suitable for 3D mechanical models retrieval.

Abstract: LED die bonder is a high precision packaging machine and needs proper tolerance design to ensure its high performance requirements and low manufacturing costs. The related tolerance design methods, such as worst-case method and statistical method, mainly focus on two-dimensional cases in tolerance design. However, tolerance design for LED die bonder needs to deal with three-dimensional cases. To solve the problem, a new method for tolerance design based on Multi-body systems is presented. According to the motion characteristics of the related assembly component parts of LED die bonder, the motion equations in ideal and actual situation for die bonding are given respectively which use the principle of Multi-body systems and the homogeneous transform matrix. By solving the motion equation, we can obtain the tolerances of the related assembly component parts.

Abstract: With the development of science and technology, the higher and higher surface accuracy of workpiece is required. The characterization of surface topography affect greatly on functional performance of workpiece. In recent years, many researchers have made a large progress on the study of surface topography and presented some related standards. The assessment of parameters of surface roughness, however, has not been researched intensively in the new generation of standards system. This paper proposes a novel roughness separation method based on B spline wavelet to analyze engineering surface. This method improves accuracy of roughness signal separation. The experimental results show that B spline wavelet can extracts accurately the roughness component and experiment results by the proposed method fit with the actual value of the standard sample plate.

Abstract: Product variant design is one of the key technologies of Manufacturing Enterprise for responding market demand. During the product variant design, dimensional tolerance variant design plays an important role. However, dimensional tolerance variant design is considered rarely in the researches of product variant design. To solve the dimensional tolerance variant design during product variant design, information expression, extraction and labeling method of dimensioning of dimensional tolerance of part dimension model is investigated. A variant design method with dimensional tolerance is presented in this paper. In the method, dimension variant design and dimensional tolerance variant design are integrated, so dimension variant design and dimensional tolerance variant design are implemented concurrently. A part variant design module with dimension and dimensional tolerance based on SolidWorks is developed for using Visual C++. Finally, an example of shaft illustrates the proposed method.

Abstract: The garbage crusher is a new kind of crusher for garbage crushing when processing Municipal Solid Waste (MSW). With the development of automatic equipment and the complication of structure and properties of the garbage crusher, the fault diagnosis of garbage crusher is very important. In this paper, according to the fault symptoms and parameters, Radial Basis Function Neural Network (RBF NN) is used for fault diagnosis of the garbage crusher. The structure and inference of RBF NN are discussed in detail. The garbage crusher fault diagnosis model is established based on RBF network. At last, the fault of mechanical system is taken as an example of garbage crusher fault diagnosis. Training simulation results of the neural network are given base on MATLAB software. The result shows the RBF NN is suitable for fault diagnosis of garbage crusher.

Abstract: The new-generation standards of Geometrical Product Specifications (GPS) take the measurement and verification of manufactured parts according to the duality principle. The Specification Surface Model (SSM) is a simulation model of the actual manufactured part which plays a decisive role in the process of duality verification. The existing methods, however, have not been found to carry out much related research on the generation of SSM. This paper presents a method to generate the SSM for the characteristic of planar feature with flatness under the standards of GPS. The mathematical model of the flatness tolerance is firstly established. Secondly, in order to get the simulation points to simulate the actual characteristics of the manufactured parts, both of the functional requirements of the parts and the influences of the manufacturing process are considered. And then the simulation points under the normal distribution are generated within their tolerance zone by computer. By using the approximation method of the least-squares SSM is then obtained. Finally, an example is used to illustrate the proposed method.