Advanced Materials Research Vols. 542-543

Abstract: In this paper, the pendulum characteristic of nature convection gas in dimensional enclosure is analyzed by FEM. Using ANSYS-FLOTRAN CFD program, the stream field and the temperature field caused by the point heat source, when the two-dimensional enclosure is inclined, has been obtained by a series of procedure, such as model building, meshing, loads applying and equation solving. The results are as follow: (1)Under the buoyancy lift affecting, the direction of nature convection gas always keeps the vertical upward in two-dimensional enclosure, nature convection gas has the pendulum characteristic. (2)When the dimensional enclosure is inclined, temperature distribution at the several points in dimensional enclosure will change with the tilt angle. The pendulum characteristic can be utilized to measure the tilt angle by the gas pendulum tilt sensor.

Abstract: From a practical point of hydraulic servo system, this paper researches on four-way servo valve working as three-way servo valve combined three-way pressure reducing valve forming differential form controlling asymmetric hydraulic cylinder characteristics using the classical control theory. According to the characteristics of hydraulic cylinder extends and retracts, it redefines the load pressure and load flow, establishes the load flow equation of control valve, the continuity equation of hydraulic cylinder and dynamic balance equations of the hydraulic cylinder which connected with the load, reaches the valve controlled asymmetrical cylinder system transfer function. Considering engineering practice, simplifying load types, it respectively obtains the transfer function of elastic load and none elastic load under the system which provides theoretical basis for analysing the static and dynamic characteristics of the valve controlled asymmetrical cylinder system.

Abstract: Research was made on the flow behavior of the 45t single strand tundish by means of water model. The model was 1:3 in size of the real tundish. Experiment conditions satisfied Froude number similarity. Minimum residence time distribution (RTD) curves were determined by pulse response. The proportion of the plug flow, mixed flow and dead volume were calculated. An optimized solution was made of a combination of turbulence inhibitor, dam and weir to decrease the dead volume (Vd) in the tundish to 11.36%, 67.8% lower than before. Production contrast tests showed that, with the optimized flow control solution, removal of oxide inclusion in slab is improved by 35.3%.

Abstract: Tackling of uncertain data is a major problem in analysis, modeling and simulation. Fractal interpolation surface and fuzzy set method are employed to solve the issue of uncertainty in modeling irregular surface. Initial interpolation data grid point is used as the kernel of Gaussian fuzzy membership function and its fuzzy numbers can be calculated by specifying λ of λ-cut set. These fuzzy numbers are used as uncertain data, which are the boundaries of the fluctuation of initial grid, and defined as a new kind of fuzzy interpolation grids. With these interpolation grids fractal interpolation surface algorithm is applied to act on. By these definitions, experimental data for modeling rock surface is illustrated to show that how the interpolation scheme proposed in this paper enhances the controllability for manipulating uncertain data.

Abstract: In this paper the implementation of the vector control and direct torque control systems for a marine permanent magnet synchronous motor has been studied. A novel control method using space vector pulse width modulation was proposed. Then the simulation models with the vector control and direct torque control using the space vector pulse width modulation method have been established, respectively. Finally, the speed control performance of the systems was verified by simulation. The simulation results indicates that the systems used vector control or direct torque control technique can meet the requirements with the aspect of marine PMSM dynamic torque response. Meanwhile comparing to the different simulation results, the torque ripple was reduced in the vector control system.

Abstract: In order to enhance AUV motion stability in inland rivers, we introduce a new kind of sliding mode control method which is improved by artificial immunity algorithm. First, AUV motion is analyzed mathematically. Due to the disturbances from both nature and human activities, hydraulics in inland rivers is very complex. Since we concentrate on AUV motion in this paper, we simplify the environmental disturbances to two main kinds of wave forces: shallow water wave and ship wave. Then, a complete AUV rolling motion equation is established containing wave disturbances and moment from propulsion system. We use sliding mode control method to adjust propeller’s motor speed and artificial immunity algorithm to weaken the chattering brought by it. Finally, simulation of this method is carried out through Matlab and it is proved to be effective.

Abstract: Based on formate cutting principle of epicycloid bevel gear, the cutter head is studied, and the formate cutting mathematical model with cradle structure is established, and the theoretical equation of tooth surface is derived, and the tooth flank deformation quantity caused by the changes of machine setting parameters is calculated. According to the relative motion and position relation between cutter and workpiece, the CNC formate machine for manufacturing epicycloid bevel gears is developed, and the machine model is established, and the machine setting parameters are solved according to models equivalence relation. Finally, a cutting experiment is conducted, and the influence of machine setting parameters variation on tooth flank deformation are analyzed, and it will provide theoretical direction for tooth flank correction.

Abstract: The hardware system of a special machine tool was improved by the structure of "PC + motion controller" by DMC 1832 controller, meanwhile software design was implemented by VB6.0. The entire motion control system was responsible for the motion controller by using the PC as the core processing section. The whole process of lathe processing was controlled by servo motor, the overall framework of transformation was given. The system has been applied to process the superfine adjustable slender axis. In addition, the system can be secondly developed according to the actual processing needs, it has broad application prospects.

Abstract: Tool radius compensation is necessary to CNC machining. However, B tool radius compensation leads to work piece burning at the sharp corner of convex contour because of the long time contacts between the work piece and tool, and C tool radius compensation frequently changes machining feed rate for its broken line tool path. This paper presents a novel tool radius compensation method suitable for high speed machining of convex contour, which have the advantages of both B and C tool radius compensation. It uses compound transition with line and arc between the adjacent blocks of CNC program. The offset tool paths of the adjacent blocks extend a small line segment respectively along their tangent direction, then insert an arc between the end points of the two extended line segments. The results of simulation and experiments show that the machining quality of the sharp corner of convex contour is improved and the machining time is shorter than C tool radius compensation.

Abstract: According to the design requirements of open CNC system,an open soft-CNC system design was proposed in this paper. The embedded microprocessor ARM and embedded operating systemμc/os-ii was used as the system development latform, introducing of hardware and software design ideas to complete the soft-CNC design and the software was packaged into components, simplified the system hardware architecture, improved the reliability, openness, and real-time of the system.