Key Engineering Materials Vol. 621

Abstract: Aiming at the limit of energy in quakeproof, aerospace and field ordnance, and requirements for damper’s different damping force in vehicle vibration’s pull and press stroke, a passive adaptive MR damper was designed and made. Passive adaptive MR damper is a new type of damper based on GMM inverse effect and MR effect, and it doesn’t need energy devices and can realize external force self-adaptation. A model of passive adaptive MR damper is established based on Jiles-Atherton model, the law of approach for the magneto mechanical effect, the magnetic circuit law and Bingham model. Experimental results show that the value of damping force is related to displacement and velocity: the larger the displacement, the greater the damping force; the faster the speed, the greater the damping force. This is consistent with the model. The damper has characteristic of load adaptive. Feasibility of the design was verified.

Abstract: The PM is the closed mechanical structure and its two platforms is connected by multiple branched. The PM is different from the serial mechanism and has many structure parameters. And the structure parameters will greatly influence the mechanism output precision. After the PM assembly is completed, the structure parameters are difficult to measure by the measuring tools. This paper presents a calibration method of structure parameters. Firstly, the destination is to ensure the structure parameters in the range of certain error through the manufacturing, assembly and the auxiliary tool detection. Secondly, the optimization mathematical model of structure parameters for PM is established by using the optimum performance of the MATLAB software, which makes the continuous learning through the sample data for PM. After continuous optimization, ideal approximate solution of the structure parameters is found in meeting the precision error range. By MATLAB simulation, the method is feasible.

Abstract: The process of electric generator stator bar-ends cure-heating is a key step during the generator production. However, since the cure-heating system is a non-linear and one-step inertial system of great coupling. Because of the resistance wire (or wire rod body resistance), air convection, the temperature and other environmental factors, it is difficult to establish accurate mathematical mode. The traditional PID control system does not achieve the desired effect. On the one hand, its overshoot is so large that the tolerance can be up to 6, on the other hand, it is difficult to regain balance once the system is perturbed. The paper makes a thermal chemical analysis of the cure-heating system, then builds a thermodynamics model. To control the non-linear and one-step inertial system, it adopts the method of Fuzzy self-tuning PID parameters to adjust the PID parameters including, and the output according to the real-time heating temperature feedback, thus, controlling the heaters action to achieve the objective of heating temperature control and solving the strong-coupling between the multi-loops of heating and improve the automatic control degree of the cure-heating control system. By simulating in MATLAB and analyzing the simulated results comparing Fuzzy-PID control effects with traditional PID, the results show that the method of Fuzzy-PID control which is used to realize the real-time control of temperature in the stator bar-ends cure-heating system can exert strongpoint and avoid shortcoming of those two control methods. As it can not only exploit the advantages of Fuzzy control, such as strong Robinson Crusoe, fast response time, small overshoot, but also possesses the high quality dynamic tracking function and better static precision of PID control, it is a superior excitation temperature control scheme for stator bar-ends cure-heating system.

Abstract: This paper analyzes the life of a kind of conveyor belt, based on the theory of the hydraulic tensioning device. Hydraulic tensioning device is a kind of machine which detects the real-time force in the conveyor belt. When the force is lower than the enactment value, the device will tension the belt to make it lager, in case of the belt skids. When the force is higher than the enactment value, the device will stop tensioning the belt. Based on the relationship between the effective strain and the life of the conveyor belt, simplify the real problem. Draw a curve of the relationship between the effective strain and the life of the conveyor belt by Matlab which can educe the stop tensioning value. Based on the theory of classical mechanics, the paper gives out the start tensioning value. At last, this paper gives out the reasonable range of the strain of the conveyor belt.

Abstract: In view of the development of wireless sensor system data transmission model in mine mechanical, we construct a ground reflection model of double path combined with the actual background demand based on the analysis of the wireless network routing protocol. Firstly, we put forward the selection strategy on wireless communication transmission power of multiple information sensor nodes. To build a data communication mode, we proposed the selection and evaluation method of network parameters based on graph theory. In consideration of the wireless channel model, combined with the initial random layout problem of network node, we explore whether to be neighbors between any two nodes arranged at random and the constraint relationship of wireless communication distance between nodes. Finally, we make up a dynamic routing selection algorithm with a view to dynamic nodes, and conduct the simulation analysis and experiment design. The research results show that with the increase of the random movement speed about network nodes, the process of depleting the energy of the nodes in the wireless sensor network speeds up, which explain the protocol given in the paper requires more energy to cope with the problem that the network topology changes frequently because of the random motion of nodes in network. The research results provide a reference to the wireless network node research and design in the electromechanical integration design.

Abstract: As the key part of nuclear pressure vessels, the water chamber head has the features of large size, complex shape and difficult processability. The processes of conventional machining method are too decentralized, the cumulative error is large, and the processing cycle is long. In order to meet the efficiency and high-precision machining requirements of the nuclear power water chamber head, a design scheme of special turn-milling machining center and B-axis components is proposed. The part characteristics and machining difficulties of the water chamber head are analyzed in the paper. The machining areas and processes are subdivided, the numerical control technological process is presented. In order to complete the finish machining of the water chamber's inner and outer surfaces and its inclined holes and sloping faces, the movable gantry milling machining center with pendulant ram is designed. According to the head processing requirements, three design schemes of B-axis components assembly, single row cylindrical roller bearing type, double row tapered roller bearing type and the central axis unloading type, are proposed. Through the theory analysis and statics and modal comparative analysis, the central axis unloading type is adopted as the optimal proposal in B-axis component design. Simulation and experimental results show that the turn-milling machining center based on the unloading B-axis assembly can satisfy the precision requirement of the water chamber head.

Abstract: Vibration of pipe is the most frequently fault appeared in chemical engineering industry. In this paper, in order to resolve the problem of vibration in exceed of the set standard for the lubricating oil pipe of 10-K-302C compressor of DuShanzi petro-chemical company, the three-dimensional model of the pipe were established by using ANSYS Workbench, and the natural frequency and mode vibration of the pipe were obtained. Through ANSYS bidirectional coupled fluid-structure analyzing method, the variety of the pressure and velocity of the lubricating oil in the pipe, vibration frequency and the displacement of the pipe under working condition were carried out. By contrasting the analysis result between the numerical simulation and measured actually, the validity and accuracy of the numerical simulation have been affirmed and it has been found that the resonance and the large fluid pressure fluctuation were two main reasons caused the pipe vibration. Based on the conclusions above, two ways to reduce the vibration have put forward and the best way have determined.

Abstract: Based on the continuity equation and the motion equation of fluid dynamics, a mathematical model of high pressure transients in water hydraulic pipeline is presented. In the model, the friction item is consist of steady friction item and dynamic friction item, using the Darcy-Weisbach equation to solve steady viscous friction item and using four exponential terms instead of weighting function to solve dynamic friction item. By finite difference method accompanied with Matlab/Simulink, an example of high pressure turbulent flow in water hydraulic pipeline is configured so as to simulate the dynamic characteristics of pressure transients. The comparison between the observed result and the simulation result shows the mathematical model of high pressure transients in water hydraulic pipeline with turbulent flow is reasonable.

Abstract: In hydraulic transmission, Hydraulic pressure can not support heavy objects long time. For the shortcoming, an electro-hydraulic lifting device is designed with mechanical structural supporting; Electric motor is the motive power. The weight is lifted by hydraulic transmission technology; the base of the device is set up a lifting rigid leg and pushing forward Casters .After hydraulic system lifting heavy objects, the lifting devices rely on the support tube, mechanical positioning tube and rigid supporting legs to lock the lifting position. In order to ensure the same high of support on different positions, a vertical fine adjustment mechanism is set. The design solves the problem that hydraulic transmission cannot lift long time. The lifting device is safe operation, easy moved, accuracy positioning, and stable support, energy-saving and environmental protection.

Abstract: Precise cable drive has been developed as a new-style transmission element that has the advantages of low backlash, high stiffness, high efficiency, no friction and no lubrication, and is widely used in electro-optical tracking system. A precise cable drive mechanism is designed in this paper. Its torque output is greater than 50Nm and precision is less than 0.1mrad. Size of the cable is selected base on the maximum load of the cable evaluated in the process of the reciprocating motion. In order to improve the driving capacity, design the cable-groove match strategy with the non-intervene cable wrapping method. A figure eight pattern wrapped method and screw pitch of the cable wrapped line is designed. The influence of the contact angle on the preload force and the influence of the preload force on the backlash are simulated by the software Matlab when the mechanism driving the maximum load. At last magnitude of the contact angle and the preload force is confirmed.