Advanced Materials Research Vols. 591-593

Abstract: The aim of this paper is to study cognitive load in the virtual maintenance training. This paper first introduces the concept of virtual maintenance training, looks back the study history of actuality and sketches the current development in the virtual maintenance training. And then, it studies cognitive load in the virtual maintenance training. In this part, this paper talks about the impact of cognitive load on the virtual maintenance training and analyzes the sources of cognitive load and the strategy to reduce cognitive load. At the same time, it points out the measurement methods for the cognitive load in the virtual maintenance training. In the last part, the research foreground for cognitive load in the virtual maintenance training is proposed.

Abstract: The valve is a valve mechanism main component, it is to ensure that the engine obtains good economic performance,dynamic performance, reliability and durability important parts. A lot of practice indicate, thermal overload is the cause of the failure of valve is the main reason. This paper conducts a simulation of working process of the R3105T3 four － stroke diesel engines of Shandong Weituo Group Co.Ltd.as an example with the Matlab analysis software.Through the simulation, indictor diagram and transient heat transfer coefficient are computed .It proposes a simulation method to compute heat transfer and deformation of the exhaust vavle.And with this method, it can predict the engine indictor diagram and describe the heat transfer situation of the exhaust valve as well as temperature distribution. So it can prevent losing efficacy of the exhaust vavle by choosing resonable related parameters. Meanwhile this article conducts heat transfer simulation and analysis of the exhaust vavle under different working conditions.

Abstract: Compression device is the important mechanism of baler. This paper uses the virtual prototyping technology. It analyzes the function of compression device in 9KG-350 high density baler and the three-dimensional digital model of compression device is obtained based on UG package .Then the model is put into ADAMS, and a kinematical simulation analysis is performed. Through the simulation, the whole kinematical process is reflected, gaining the relative kinematical curves of compression device as well. The results can be help in study the design of baler and the structure optimization.

Abstract: Heavy-duty forging manipulators play an important role in extreme manufacturing. Based on the kinematic model of DDS forcing manipulator, the input- output relation equations in terms of position are derived. According to the actually movement path of output mechanism, a new decoupling concept is defined as to forcing manipulator. The input-output relation matrices in terms of velocity are established at three major motions, and the coupling characteristics of mechanism are analyzed. At last, the theory analysis is proved correct by experimental verification. The results show that three major motion mechanisms of DDS forcing manipulator are partially decoupled under the new decoupling concept compared with the conventional one, which helps to simplify the control strategy of DDS forcing manipulator.

Abstract: The heat sink has played an important role in the thermal design of high power LED lamps. In this study, a pin-fin heat sink is designed for the 3-chips high power LED down-light. Thermal performance of pin-fin heat sink is researched by changing the fin height, fin number and lamp’s irradiation angle. Simulation results gotten by CFD software show that the pin-fin heat sink has better thermal performance with fin height of 40mm and fin number of 75. The LED down-light with a pin-fin heat sink has a better cooling effect in multi-angle irradiation. The results provide a reference for future design of pin-fin heat-sink.

Abstract: Through analyzing several common errors that have impact on the kinematic accuracy of globoidal cam mechanism, finally a mathematical model of globoidal cam impinged with error was established. By using the differential method, the motion accuracy influence coefficients of the globoid cam mechanism were obtained. The change rule of kinematic accuracy influence coefficient with the change of globoidal cam rotation angle was analysed with practical cases. The analysis result shows: different error factors lead to different influence coefficient; Radius error of the index disc roll has the greatest impact on motion precision, while shaft angle error almost has no influence on the movement precision; The meshing position of the globoidal cam mechanism affects the kinematic accuracy volatile; Moreover, each motion accuracy influence coefficient has a certain relationship with the structure factors of globoidal cam.

Abstract: Taking planar pivot four-bar mechanism for example, the method motion reliability simulation on solving motion reliability of planar linkage mechanism is proposed in this paper. Under the circumstances that manufacturing errors and joint clearances are normal distribution, ADAMS is taken as the analysis platform and the parameterized model of planar linkage mechanism is established by it, then Monte Carlo theory is used to calculate in order that different random simulation model can be obtained. After cycle simulation, the data of simulation will be saved in text files so that it could be used for calculating the result of motion reliability. This method is applied to solving motion reliability of the opening/closing mechanism of the bottom door in the coal hopper, and the result is reasonable, thereby its effectiveness is proved successfully.

Abstract: CAD/CAM techniques together with NC machining allow to reduce products manufacturing time and costs. The aim of this paper is to present a brief overview of reverse engineering as a necessary phase which provides benefits to the design and production processes in advance. Taking blades as object of study, one method is proposed to improve the design efficiency for blades model reconstruction and NC machining. The process consists of three main components: 3D optical digitizing, model reconstruction and NC machining. First of all, point cloud data acquisition is made through camera type 3D scanner, and the data pre-processing is made by Geomagic software, then it is imported in CATIA software for model reconstruction and generating NC code. Results show that this method can improve the efficiency of blades model reconstruction.

Abstract: According to the configuration theory of the parallel manipulator with a few degree of freedom (DOF), the paper adopted 2PSU-U mechanism to design a new parallel tilter with 2 DOF, which has such advantages as strong bearing capacity, high precision and kinematic decoupling. It used the coordinate transformation to establish the position and velocity equations of the tilter, and also used the instance to make kinematic simulation, whose result indicated that the roll and pitch angle of the moving platform can vary according to the set motion law by driving two sliders of the main moving branched chains.

Abstract: Considering the attitude stabilization requirements for an unmanned marine platform equipped with electro-optic detection equipment, a stabilized platform based on a 2-DOF parallel mechanism has been designed. The stabilized platform, especially for the requirements of small space and high load inertia, has such transmission branch chain with fixed ball-screw. The structure, DOF and kinematics of the platform has been analyzed, besides, the mathematical model of the platform's attitude inverse solution has been established. Numerical simulation for the derivate mathematical model and ADAMS simulation analysis has been done. In order to verify the correctness of the mathematical model, the motion process of the load-platform is described by a time function. The time function of the drive components calculated from the above two ways is used for the comparison of numerical simulation and ADAMS simulation. The results prove that the mathematical model established in this paper and ADAMS simulation results coincide.