Advanced Materials Research Vols. 139-141

Abstract: A nonlinear dynamics bond graph model of gear pair is established including the time-varying stiffness, transmission error and tooth surface friction. A capacitive component C is introduced to represent the loads and tooth elastic deformation while introducing the concept of switched power junctions (SPJ) to describe time-varying gear mesh stiffness with clearance, and flow Sf represents the influences of the gear transmission error on the system dynamic equations. The tooth surface friction bond graph model involving the relationship of the relative velocity and the direction of friction are developed. According to the causal relations and the power flow, the state-space equations of the gear bond graph model are obtained. Research results show that bond graph modeling method can solve the modeling problem of the gear nonlinear dynamics.

Abstract: MFPSE, Micro Free Piston Swing Engine, is a new type of miniature internal combustion engine based on the working principle of two-stroke swing engine. The successful development and operation of this type of miniature internal combustion engine provide important significance for the miniaturization of the internal combustion engine, and provide a number of important research theory, computation method and experimental data. In this article, according to the work characteristics and co-ordination requirements of MFPSE (Micro Free Piston Swing Engine), whose strain interference is analyzed using finite element analysis software, the problems and interference of the center pendulum and cylinder is found evidently. The data of analysis provides theory basis for the MFPSE’s structural optimization, and is critical to improve the performance of MFPSE.

Abstract: This work investigates dynamics of a three-stage gear system in a new power-driven turret. This paper mainly consists to develop two kinds of dynamic models of the main drive train. One is the dynamic contact model of the gear system to calculate the dynamic meshing forces and the tooth root stresses. The other is a virtual prototype model adequately incorporating the deformability of the bearings to analyze the dynamical response. The dynamic meshing force and the tooth root stress were compared with the theoretically calculated results. The vibration acceleration signals of the turret were gathered by tests. According to the experimental data, the simulation results of the virtual prototype model were given based on which the rationality of the virtual prototype model is verified.

Abstract: Pump-control-motor hydraulic drive system is a common used volume speed-modulating loop in hydraulic control system. Aiming at the working conditions of the cutter head of the tunnel excavator used in the large underground excavation, a pump-control-motor hydraulic drive system was applied that composed of three variable displacement hydraulic pumps and eight hydraulic motors, which can control the rotate speed of the cutter head in real time. The simulation model of the pump-control-motor was established using the AMESim software. The relationships among the rotate speed, torque of the cutter head and the system pressure, system flow were investigated in detail under several typical working conditions in tunneling. The relevant results can provide theory references for design of pump-control-motor hydraulic control system in other occasions.

Abstract: Underwater manipulator as efficient tools plays important roles in ocean exploitation. Because of its specificity for underwater operations, the structure of an underwater manipulator should be designed compactly with light weight and small size. Structure of a 7-function underwater manipulator is designed here. Except forearm rotation and wrist rotation which use hydraulic motors, other functions are driven by hydraulic cylinders, whose parameters are determined by force analysis and limit positions. The hydraulic pipelines from the elbow joint to the end are passed through the forearm, and the hydraulic cylinder of the jaw is integrated into the wrist motor. Built-in pipelines are achieved in the designed structure and the whole weight and volume are greatly reduced by integrated and optimized design.

Abstract: In this paper, we present the design and implementation of a VRML multi-user layer, which is introduced in the virtual reality platform. A novel 3D simulation system supporting tunnel boring machine (TBM) design is developed. The virtual environment (VE) of the TBM is established by VRML based on virtual reality technology, the 3D assembling model is built by Solidworks software and changed into the virtual environment by VRML format. The optimal method is put forward by three steps optimization data to realize transmission of network. The motion simulation and virtual assembly program for TBM are made by VRML/Java language with the movement simulation control function to realize motion simulation. It has the advantages of free installation, authenticity, interactivity, low-cost, portability, and low requiring for the clients and so on.

Abstract: As core functional components of the medium and high grade CNC machine tools, the power-driven turret involves high technology and complicated structures. Traditionally, in the study of low speed turrets` performances, the effects of thermal influences are often negligible. However, on the high speed conditions, thermal effect cannot be neglected. This paper establishes the high speed turret 3-D Model and the Finite Element Model (FEM), and investigates and analyzes temperature fields and thermal deformations. Experimental measurements are implemented on the surfaces of the original model turret in order to compare with the simulation results, modified turret is analyzed, and thermal behaviors are proved to be available on the idle operating conditions. It manifests that the distributions of the thermal behaviors have intensive relations with the speeds of the transmission system.

Abstract: From the principle of generating method, the precise model of an involute herringbone gear was built. The accurate load distributions of herringbone gear were obtained in different meshing positions in linear programming method. Then the changing course of root bending stress along with the variation of meshing position was gained. The calculation process realized the automatic definition of loads and boundary conditions, and found out the value and the position when the tooth root has maximum bending stress. The results showed that the maximum stress usually appears near the position when the tooth bears maximum load. Be different from spur gears, the maximum stress of herringbone gears will possibly appear in the section where more teeth couples are engaged. The analysis can effectively provide reference for checking tooth bending strength of herringbone gears.

Abstract: The hydraulic bulging strengthening technology is a kind of strengthening technology of large generator’s retaining ring. In the right punch working angle and sealing pressure of equipment, the ring billet is deformed uniformly by high pressure water. The experiment in 5MN oil-hydraulic machine proves that the ring billet is deformed uniformly while the punch working angle is 60° and the pressure between the punch and the rings is 1MN. When the internal and external diameter deformation of the ring billet is 8.5% and 14.0%, the external generatrices of the ring are nearly line. The ring billet is 1/5 of 300MW18-18 steel retaining ring. It may improve productivity to measure real-time thickness of the ring billet with ultrasound sensors and control pressure of the oil-hydraulic machine and ultra-high pressure pump with 80c51.

Abstract: The Loaders’ hydraulic transmission system trends towards medium and high-pressure. The research object of this paper is thermal equilibrium of new quantitative medium and high-pressure hydraulic system of type 50 of wheel loader, which is developed by Xiamen Xia Gong (XG) Machinery Co., Ltd. (abbreviated as XGMA). Aim is to research the thermal equilibrium of loader’s hydraulic system before increasing the pressure at 16MPa and prove the simulation results reliability through experiment (max error is 11.57%). The simulation results are thought to be reliable, after ignoring some disturbance factors existing in the practical work. Consequently, loader's thermal equilibrium have been done after increasing pressure to 20MPa, the results of research show that thermal equilibrium will be obviously optimized, it will drop power loss (drop 17%) and improve hydraulic system’s reliability and reduce the cost after pressure was raised.