Papers by Author: Cong Da Lu

Abstract: Thin-walled spatial bending tube can not only provide engineering design with higher flexibility and lighter structure, but also enhance the construction of space saving and aerodynamics improvement. Based on rotary draw bending technique, a new method for spatial consecutive bending with no straight line for thin-walled tube was put forward. Firstly, a new bionic elastic mandrel was developed by analyzing the structural characteristics of the squilla. It mainly consisted of bowl-shaped mandrel balls, an elastomer and a mandrel shank. The bowl-shaped mandrel balls, nested matching one another, generated a non-smooth surface which can provide continuous support for internal surface of the tube wall. It could also achieve small bending radius. The elastomer featured of certain bending stiffness and enough tensile strength. Secondly, a curved clamping die was advanced to clamp the spatial consecutive bending tube with no straight line effectively. Based on the shape of the bending tube after the former bending forming process, the curved clamping dies which can match the shape of the former bending tube were designed for the later bending. Lastly, bending experiments was performed. A thin-walled tube made of Q235 with two passes, one bending angle 90° and the other 180° was taken for example and the spatial consecutive bending tube with no straight line was successfully obtained. It is of significant importance in enriching the spatial bending tube technique and achieving the small bending radius.

Abstract: As many countries increased investment on clean energy research and the automobile industry developed rapidly, fuel cell vehicles hold its own place in the history of the automobile industry gradually. By analyzing large car companies in proton exchange membrane fuel cell (PEMFC) car research and fuel cell car customer requirements, study the design and manufacture of fuel cell vehicles, give some countermeasures for design research.

Abstract: This paper summarizes the performance of PEMFC catalyst layer. The main materials used as catalyst in PEMFC are presented as well as the typical structure of MEA. Functions of catalyst during the operation of PEMFC are discussed in detail. Catalyst plays a key role in accelerating the rate of electrochemical reaction, especially that of reduction with oxygen in cathode. But its high cost and low tolerance for has resulted in a severe fact that essentially all the longevity of PEMFC which adopts precious metal-platinum or platinum alloys as catalysts is relatively short. A sputter deposited method is presented to enhance the efficiency of catalyst in PEMFC, while whether this method would bring about a striking effect or not remains worth further researches.

Abstract: Object recognition and reconstruction plays an important role in the area of 3D robot vision, which has wide applications in autonomous mobile system. For communication between heterogeneous applications, generalized and universal object description file format is needed to be developed to replace proprietary file format. In this paper, first, a new object description model was designed by using XML Schema definition language. Second, based on the description design, a dynamic link library (dll) was implemented for converting data format among different systems. At the end, experimental results are demonstrated.

Abstract: Screw thread, as the most basic and widely used mechanic element, has many traditional methods to verify its dimension consistency. Machine vision technology is gradually applied to inspect screw thread in fastener industry because of its fast, precise and repeatable features. Based on analysis of the features and problems of previous vision measurement methods, this paper provides calculation, analysis and simulation of screw thread’s 3D mathematic model, and finally provides corresponding algorithm to correct calculation error resulting from shading effect of backlight projecting.

Abstract: Experimental research on the surface quality parameters such as roughness and removal rate in the precision lapping of sapphire was promoted in this paper, effects of processing parameters as load, speed of rotation, grain size and density on sapphire surface quality was studied by experiments. Results showed that lapping load and rotate speed were the most important factors on the removal rate, grain size played a key role in the removal rate and roughness under the same conditions, profile tolerance of surface shape depends on the flatness.

Abstract: Most of the input of parametric design system is the specific structure parameter, which is in a detailed design stage. To promote it into conceptual stage, the function-structure mapping problem is proposed. To solve the problem, the function -structure mapping mechanism which is based on logical view and in the framework of axiomatic design is established, the mapping model is solved by optimization method and the mapping procedure is integrated with parametric design system. Function requirements are mapped into a parametric model directly. Finally, a forklift design process validates the method and shows its advantage.

Abstract: Fuzzy logic is a mathematical theory of inexact reasoning that allows modeling of the reasoning process of humans in linguistic terms, and it is an effective method approved to deal with the fuzzy objects in many areas of engineering application. The purpose of this paper is to explore the relationship between grinding process parameters and surface quality parameters of sapphire wafer by using fuzzy theory and to obtain optimization parameters to enhance the processing efficiency and higher the surface quality of the sapphire in ultra-precision grinding. This paper sets up the triangular fuzzy logic model between processing parameters and surface quality parameters for precision lapping of sapphire, and 2 groups of optimization parameters are selected. Finally, the experimental results verified that the optimization parameters of sapphire lapping obtained by using fuzzy logic which can improve the grinding efficiency and the surface quality of sapphire.

Abstract: This paper presents the parameters optimization by TRIZ theory in the precision lapping of sapphire in order to realize the high efficiency and low damaged lapping. The TRIZ theory was used to optimize processing parameters of sapphire precision lapping based on much experimental data of lapping, then the conflict matrix of internal contradictions was set up and the optimization parameters was obtained. The result of experiment indicated that the face quality of sapphire was improved greatly after optimized by TRIZ. There was a conclusion that TRIZ theory can be used to optimize the processing parameters of sapphire precision lapping which is important to enrich the processing theory of sapphire.

Abstract: Fluid magnetic abrasive (FMA) is a new precision finishing process. It has the capability of processing free shape surfaces and complex cavities. Due to its strong adjustability and controllability, FMA could be regarded as the final process of machining which could greatly improve the surface quality of workpiece. The paper first introduces the component and machining mechanism of FMA, secondly it describes the model of the material removal in the process, thirdly it presents the devices of FMA polishing. At the end, a grinding head tool based machining mode is proposed for realizing the polishing of internal cavity.