Materials Science Forum Vols. 628-629

Abstract: In this paper, to improve the transmission ratio discontinuity problem during the gear shift process in the multi-gear fixed step ratio transmission of the tractors, a hydro-mechanical continuously variable transmission (HMCVT) for tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of the variable displacement pump (PV) and the fixed displacement motor (MF) and a multi-gear fixed step ratio transmission. Its stepless-speed-regulating characteristic, smooth range shifting condition and transmission efficiency are analyzed. The analytical results show that the tractors assembled with HMCVT can gain wide speed range and high transmission efficiency. There are eight high efficiency pure mechanical gears in the whole speed range, which is benefit to improve power and economic capabilities of vehicles.

Abstract: Success of rescue process is determined by reliability and safety of rescue device. Virtual prototype technology is introduced into the dynamics simulation and optimization for the design of an operating mechanism for loading deep submergence rescue vehicle, and the 3D CAD software, multibody system dynamics analysis software were combined. Taking into account wave excitation input at sea state 5 and 8 as the extreme marine working conditions, the virtual prototyping model of the operating mechanism is built by ADAMS. The whole topology relations of the vehicle are defined. Dynamics characteristics of key parts are analyzed in various virtual environments, which is quite difficult to be realized by physical tank test. Optimization strategy is proposed and verified by increasing the number of horizontal wheels and adding gap between horizontal wheels and the track. This method offers a new way to study the innovative design of similar marine special mechanism.

Abstract: A significant amount of research has been performed to explore the result of components tolerances on assembly quality. The paper analyzes the geometrical error sources which affect spindle rotation accuracy of turntable. Then it predicts the spindle rotation accuracy using vector dimension chain which is the most proper method to analyze assembly quality. The method is validated by tests and it could afford theory reference for spindle rotation accuracy analysis. And the computed value suggests the bearings’ rotary precision could be lower to save cost.

Abstract: The principle of generating conjugate tooth profile for elliptic gear was studied. On this basis, 3D modeling and parametrical design of elliptic gear were realized by using Solidworks API. The program provides a useful tool for further using finite element analysis to conduct strength analysis, numerical manufacture and computer aided simulation.

Abstract: An enhanced product representation model was introduced, and it was specified with the sets of property, the sets of the multiplicity of modules, and the sets of relationships among them. A multi-case base corresponding complex product decomposition was established. Cases were defined and edited on customization template, which improved efficiency of developing multi-case base. For an example, a design tool for diesel engine development based on multi-case base was developed, and diesel engine product development could be more rapidly.

Abstract: Air Nailer is a kind of hand-held pneumatic tools driven by compressed air, the Air Nailer work process is complex. With CAE, designer can detect and make the resolution of design problems in time, but it is difficult to master the CAE technology. On the design of Air Nailer in most enterprises, nearly 85% of the parts are only need parameters changing and maybe need few structural adjustments to make the assembly properly. With this, a systematical method for Air Nailer CAE with the parametrical CAE analysis, template-based CAE analysis and dedicated CAE analysis is proposed in this paper which can make the designer to use CAE tools to improve its Air Nailer design more efficiently. The program tools of VB and APDL of ANSYS are used. The CAE analysis templates and navigation tools are established to meet the different CAE purpose.

Abstract: Hydraulic components are widely used in mechanical industry. To comply with the requirements of modern products for high quality and performance, hydraulic components are required to improve their own efficiency and controlling capability. The hydraulic pump, as a main element for energy conversion, exerts tremendous influence on the overall output efficiency of a product. The first is the energy loss analysis of a hydraulic pump, which is aimed to enable the pump to achieve a higher efficiency. Theoretical calculations may deviate to some extent from the experimental data as the equation of fluid motion is calculated based upon the ideal fluid; moreover, the leakage at the tooth meshing though at little amount, the friction loss between the shaft and its bearings, and the friction loss due to the meshing of gears were not considered during modeling. To determine the optimum clearance, it is necessary to take into account the workmanship factors, thermal expansion and contraction, frictional resistance, working conditions and any other factors as a whole. This was followed by obtaining the optimum clearance at the minimal power loss from the energy efficient perspective. These above-mentioned conclusions have some instructional significance over the design of the hydraulic pump.

Abstract: According to mesh reconstruction problem of point cloud models with similar topological structure, a mesh reconstruction algorithm of point cloud model is presented based on deformable template and local ICP algorithm. Firstly, point cloud model and template model are aligned in the least squares sense by human-computer interaction. Use the set of point cloud to construct k-d tree and search correspondence of vertices of template model in the point cloud model. Then, the set of correspondence Φ, between two models, is built. For any point Vi of template model, the transformation Ti of each point Vi is computed based on a local supporting neighborhood Vi : Nk(Vi) around Vi. For computation of Ti, we consider only the local correspondence that is inside the local supporting neighborhood Nk of Vi :Φ| Nk(Vi). In the iterative course of deformation, reduce local supporting neighborhood of each vertex Vi gradually to make it accurately approach point cloud model step by step. When the error between two of them is less than a given value, current template model can be taken as the reconstruction model of point cloud. It’s proved by example that the model we get can satisfy engineering request.

Abstract: The reliability of a mechanical system is not simply determined by the reliabilities of components composing the system. For a specified system configuration, system reliability depends on not only component reliability, but also the degree of the dependence among component failures, which can be characterized by load roughness in an extent. In the same way, system complexity depends on not only the number of components that the system contains but also the dependence among component failures. This paper analyzes the main factors that affect the relationship between system reliability and component reliabilities in term of component failure dependence. The factors include load uncertainty, component strength uncertainty, and load roughness as well. Traditional parameter describing system complexity is modified, new parameter to describe component complexity is defined. These parameters play important rule for system reliability design or system reliability allocation.

Abstract: The heat deformation failure form of workroll bearing chock in Bao Shan steel 2050mm hot strip mill was studied by using finite element method. This phenomenon indicates that the internal friction heat in the bearing is the major heat source that results in temperature rise. With the establishment of reasonable temperature boundary conditions on free and contact surfaces, the heat conduction model of bearing chock was built and discreted. By means of finite element method and three dimensional FEM program, the rules of temperature distribution and heat stress distribution of bearing chock were discussed. Moreover, some suggestions on bearing improvement were brought up.