Key Engineering Materials Vol. 568

Abstract: According to the FEA simulation results of tooth deformations in the mesh process, the profile modification of the involute spur cylindrical gear pairs used in timing transmission system of an automobile are designed based on the methods and theories proposed by domestic and oversea scholars and experts. The dynamic simulations of the gear pairs with straight line modification profile and involute modification profile under different values of modification amounts are done using dynamic analysis software ADAMS. Then it is testified by simulation results that (i)the mesh impact between the gear pairs with involute correction profile is obviously smaller than those between the gear pairs with straight line correction profile and without correction, (ii) optimized value of modification amounts of the gear pairs with involute correction profile is different that of the gear pairs with straight line correction profile under the same work condition.

Abstract: Different from the general 6-SPS Stewart platform, 6-PUS parallel mechanism is a kind of fully parallel mechanism whose actuators are all fixed at the frame. The advantages of this mechanism are light movable mass, small inertia and good dynamic characteristics. This paper is focused on the singularity analysis of the 6-PUS parallel mechanism. Based on the Jacobian matrix which is derived from the kinematical equation, the analytic singularity locus equations are obtained and the three types singularities of the parallel mechanism are analyzed. Moreover, the position-singularity of the mechanism is discussed through some specific examples.

Abstract: The assembly process planning of hull block is an important point in the study of manufacturing automation and computer integrated manufacturing system (CIMS), which will influence the construction period and quality in shipbuilding negatively. Based on the assembly level model, this paper presents a new design of assembly process planning for hull block. With the improved disassembly method, we can get the reasonable planning of assembly sequence. At last, the whole assembly process was simulated based on DELMIA software. The results show that the study will be instructive and meaningful to the assembly of hull block.

Abstract: In order to meet the lightweight design requirements of one swing-type plate shears, the topology optimization method is applied to improve the structure of bed. According to the analysis of the actual working conditions, the reasonable load and boundary conditions are determined. The conceptual model of bed structure is established by using topology optimization method. Lightweight improvement scheme is proposed based on the topology optimization results, and the rationality of scheme is verified by test and analysis. Different parts of the bed are thickened or thinned, and the influences of different thickness of the stiffener on the maximum principal stress, total displacement, displacement in Y direction and weight of bed structure model are analyzed. A reasonable lightweight scheme of shear machine bed is proposed. The weight of the bed is reduced and the lightweight purpose is finally achieved in the case of meeting the requirements of shearing accuracy.

Abstract: In order to solve the problem of automation electric plating gear surface, the numerical control electric plating machining tool was developed based on open numerical control system. The relative movement and velocity of anode nozzle was controlled by the motion control model. The selection of working solution and the continuous feeding liquid were achieved by use of the digital I/O module. The technological parameters, such as working current, the temperature of plating solution, PH value, and so on, were collected by the module of analog quantity acquisition and stored in the computer. Based on the preliminary experiments, the machine tool was reliable higher and the distribution of plating thickness on the tooth profile surface was uniform. The automatic electric plating technology was realized on the tooth profile surface.

Abstract: The design consists of STC89C51 MCU, the GPS15-XL receivers, LED display, servo motors, voice timekeeping and other components .And it is the GPS control system for tower clock, with timekeeping, display, automatic error correction functions. The design captures accurate time information from satellites by GPS15XL-W receiver chip, and collects and deals with time information received from SCM. And then it adjusts the clock. The SCM system consists master clock, and drives the secondary clock through giving out pulse to a servo motor. The system can also achieve the automatic error correction after power on, to change inconvenience of the traditional correction, reduce the mechanical errors. And the tower clock accurate up to ±1µs. There is no cumulative error.

Abstract: 4-DOF asymmetric parallel manipulator 2TPS /2TPR is researched in this paper. Firstly, the structure of 2TPS /2TPR is described in detail. Optimized design variables and constraints are sure. Then multi-objective optimization is built by flexibility and workspace of structure. Finally, design optimization of 2TPS/2TPR parallel manipulator based on GA. The optimal size combination of 2TPS /2TPR parallel manipulator is got.

Abstract: The method research of planetary gear trains (PGTs) by applying topological theory is very significance in searching for innovative planetary trains. A new graph representation and stratification standard are introduced firstly. Then three topological graphs of basic structure of PGTs are established as the basis of synthesis theory. Next several kinds of planetary trains with small teeth difference and method of isomorphic determination are presented, thus built up the procedure of PGTs by graphs and example. Finally a new system of classification and synthesis for PGTs is put forward according to the feature of loops in topological theory.

Abstract: Risk warning evaluation index system of independent innovation is established according to the process of innovation activities of high-tech enterprise, Chaotic Analysis Method is introduced into the BP(Back Propagation)Neural Network Model to research the early risk warning of high-tech enterprises independent innovation, the empirical results show that the integration of early warning model is feasible and effective, and significantly improve the convergence speed of network training, to some extent, avoid getting into local minimum.

Abstract: LDM process is used for preparing three-dimensional scaffolds for tissue engineering rapid prototyping technologies. Because of its forming process is complex, which influenced by a variety of factors, so the processing environment is not stable, the forming of scaffold pore size can not be guaranteed, therefore the forming precision is poor. However, the scaffold pore size accuracy is mainly decided by the wire filament width. Neural network theory and development provides a powerful tool for the study of nonlinear systems. This article analyzed the influence factors for forming bone scaffold filament width of LDM process, based on improved BP neural network, using MATLAB software programming, then predicted the filament width. The results show that model prediction error was less than 8%, it has high forecasting precision, and it can be used to guide the LDM process parameter selection and forming precision of prediction.