Jiangxin Yang

Study on functional specification scheme on interface based on positioning features

This article proposes a scheme for functional specification in accordance with the new generation of geometrical product specification. The scheme is to decompose a geometrical functional requirement on a complex mechanism into geometric specifications defined on key parts. The assembly is analyzed by graph theory. The general geometrical functional requirement is analyzed and decomposed if necessary, with geometrical tolerances specified on ending parts. Then geometric variation model is built according to the invariant degree of freedom of both datum reference system and tolerance zone, which is subsequently used to validate the sufficiency of the datum reference frame on positioning features, thereby inferring joints that perform key roles in affecting function. After a series of topological rules formulated and validation algorithm applied, datum reference system is validated and detailed specifications are generated on joint surfaces. Those specifications on underlying parts or subassemblies are then defined as new geometrical functional requirements and should be further developed. Therefore, the designer can carry out an effective recursive approach capable of realizing each geometric specification on key features while ensuring functional tolerancing of the entire assembly. A case study is given to validate the proposed method.

Multi-scale prediction of the geometrical deviations of the surface finished by five-axis ball-end milling

Surface quality and accuracy are the main factors which affect the performance and life cycle of the products. Due to the complexity of the machining process, it is difficult to evaluate the machined surface real time. Simulation of the machining process became the main method to predict and control the quality of the machined surface. This article developed a multi-scale simulation system to predict the overall geometrical features of the milled surface. The effects of locating errors, geometrical errors of the machine tool and tool deflections on the quality of the machined surface are included in the proposed model. Also, different strategies are employed to evaluate the macro-scale and micro-scale geometrical deviations of the machined surface to balance the time cost and accuracy. In comparison with the traditional method, both the form deviations and roughness feature of the machined surface can be predicted. Since the static and dynamic properties of the machining system were considered, both the stable and unstable cutting conditions can be analyzed by using the proposed method. At the end of this article, case studies are carried out to validate the proposed method. The effects of the locating errors, geometrical errors of the machine tool and cutting parameters on the quality of the machined surface are analyzed. The significance of their influences on the quality of the machined surface was investigated.

Study on Resource Configuration on Cloud Manufacturing

The purpose of manufacturing is to realize the requirement of customer. In manufacturing process of cloud system, there exist a lot of resource services which have similar functional characteristics to realize the requirement. It makes the manufacturing process more diverse. To develop the quality and reduce cost, a resource configuration model on cloud-manufacturing platform is put forward in this paper. According to the generalized six-point location principle, a growth design from the requirement of customers to entities with geometric constraints is proposed. By the requirement growing up to product, a configuration process is used to match the entities with the instances which the resources in the database could supply. Different from most existing studies, this paper studies the tolerance design with multiple candidate resource suppliers on cloud manufacturing to make the market play a two-level game considering the benefit of customers and the profit of resources to give an optimal result. A numerical case study is used to illustrate the proposed model and configuration process. The performance and advantage of the proposed method are discussed at the end.

Tolerance specification of the plane feature based on the axiomatic design

Tolerance specification involves selecting tolerance types for functional or assembly features to control the variation of features. General methods tend to formulate a frame to specify all the features of part, while the specification methods or reasoning rules for specific feature (point, line, plane, cylinder, etc.) are less studied. This paper focuses on the tolerance-type selection of the plane feature. The theory of axiomatic design is introduced to select the tolerance type for the plane feature, and the problem is interpreted as a redundant decoupled design. To achieve the functional requirements, design parameters and constraints of physics domain are determined. The mapping rules, which are between design parameters and functional requirements, are generated based on the independent axiom. Considering the large number of solutions of the design, the constraints such as cost and inspection methods are introduced to reduce the number of solutions. The minimum information axiom is introduced for the optimum mapping rules and the tolerance types are selected by the optimum mapping rules for the plane feature. Finally, the specification process is concluded and demonstrated by means of an example.

A novel tolerance analysis method for three-dimensional assembly

Three-dimensional tolerance analysis is increasingly becoming an innovative method for computer-aided tolerancing. Its aim is to support the design, manufacturing, and inspection by providing a quantitative analysis of the effects of multi-tolerances on final functional key characteristics and predict the quality level. This article proposes a novel approach for three-dimensional assembly analysis—a hybridization of vector loop and quasi-Monte Carlo method. The former is used to establish the three-dimensional assembly chain and obtain the assembly function. The latter is adopted to generate n sets of dimensional values according to the distribution of each dimension in chain. The new method is shown to inherit many of the best features of classical vector loop and quasi-Monte Carlo, combining easy-to-obtain assembly function with accurate statistical analysis. For every set of dimensional values, one sample value of a functional requirement can be computed with the Newton–Raphson iterative procedure. A crank slider mechanical assembly is shown as an example to illustrate the proposed method.