Advanced Materials Research Vols. 230-232

Abstract: A new type of high speed vertical machining centre which adopt gantry type structure is introduced. Both static and dynamic analysis is carried out before optimization. The optimization of Beam includes 2D and 3D topology optimization. Based on the result of topology optimization a new structure of Beam is developed. It is proved that the static and dynamic performances are both improved.

Abstract: After the three-dimensional solid modeling of the SG135 automobile gearbox, finite element analysis models of static, transient and harmonic response load are built based on correlation theory. On the basis of ADAMS dynamic simulation of different gearbox gears, transient load of the gearbox casing at different working gears is found out. With frequency response characteristic of gearbox casing analyzed at typical working conditions of first gear and reverse gear, the evaluation of some factors such as strength and stiffness are given out, which provides theory basis for further improvement of gearbox casing structure and strengthening weak links. Based on harmonic response analysis, the impact on gearbox casing structural vibration by harmonic excitation of the engine is imitated, and the match relation of frequency response between the gearbox and the engine is analyzed. Improvements about engine operational limits matching and gearbox structural design are proposed.

Abstract: In mechanical manufacturing, the traditional methods adopted for deburring and finishing is not only high labor intensity, but also difficult to reach the surface roughness and requirements. The vibration grinding deburring and finishing process method is put forward, and the removal of micro hole drilling burr and surface finishing experiments are carried. It can be seen from the experimental results that the vibration grinding process method can thoroughly remove burr and get the finishing effect. The vibration grinding system has the features of low cost and brief operation. The vibration grinding new process method has high practical value.

Abstract: Handling behaviour of articulated vehicles combination is more complex and less predictable than that of non-articulated vehicles. It is usually difficult for drivers to maneuver a tractor semi-trailer during high speed emergency braking on split-mu road surface. Braking on this type of road surface, the conventional anti-lock braking systems will cause the vehicle deviate from the desired direction, or overmuch stopping distance. In this paper, a 3-dof of tractor semi-trailer model was used to produce desired yaw rates which were compared with actual yaw rates. An active front steering control and four-channel ABS were integrated to improve the tractor semi-trailer lateral stability while braking on split-mu road surface, which will produce maximum braking force. A full function tractor semi-trailer model was built and assembled in multi-body dynamics software, and the dynamic analysis was performed on split-mu road surface. The simulation results show that the integrated system can improve the tractor semi-trailer lateral stability under braking on split-mu road surface.

Abstract: This paper is to analyse rolling cone worm drive model by the way of the finite element on sub-module Pro / MECHANIC of Pro / ENGINEER software and to get the stress distribution contour when the structure is on the static load.,then to sum up the stress distribution.

Abstract: The voltage and current signals are transient signals with singularity and mutability when single-phase-to-earth fault occurs in high-voltage transmission line, of which the singular point and mutations parts contain rich fault information. However, wavelet analysis just has the nature of singularity detection and zoom properties, which is very effective in singularity analysis and singular points location. Based on the basic principle of wavelet analysis and signal singularity detection, simulation and detection of singularity of fault voltage and current signals in high voltage transmission line are made by db5 wavelet multi-scale comprehensive analysis method. The singularity detection and calculation program are accomplished in M-file form by programming in MATLAB, the simulation results show that db5 wavelet can detect the singularity of fault signal and determine the fault occurrence and end time fast and accurately. This method enhanced accuracy and reliability of single-phase-to-earth fault detection.

Abstract: Making use of the advantages of the soft and hard threshold methods proposed by Donoho, this paper presents a deviation variable based on quadratic polynomial and differentiable improvement function, according to the characteristics of the underground water pipe leakage signal. In the paper we constructed the mathematical model of the function, utilized wavelet de-noising algorithm for the collected ultrasonic signal de-noising, compared the de-noising effect by means of the value of Signal to Noise Ratio (SNR) and Mean Squared Error (MSE). Results show that the new function has the better de-noising effect compared with the original threshold function.

Abstract: In the die casting mould design, there is some over-constrained locating which have serious influence on the manufacturing and life-span in some certain spots. In this paper, over-constrained locating of die casting mould structure was studied based on the example of slider block core pulling mechanism. Some improving measures in die casting mould structure design were presented in this paper. Changing the rigid connection between slider block and side core into floating connection, forced action can be applied on the side core by the slider block only from the necessary radial side instead of from other directions. Side core can be located according to the constraints of insert core hole. It simplified the machining and assembling of slider block core pulling mechanism. Thus, the manufacture cost of the die casting mould was also reduced.

Abstract: This paper proposes a noncontact magnetic suspension of an iron ball using a flux path control mechanism. In this system, the suspension force is generated by a disk-type permanent magnet, and controlled by varying the angle of the permanent magnet that is driven by a rotary actuator. In this paper, first, the suspension principle is explained, and the prototype is introduced. Second, the characteristics of this system are examined by some basic experimental results. Third, a model is created, and the numerical simulation is carried out. Finally, the suspension experiments are succeeded using the prototype, and the results are shown and discussed.

Abstract: Transient dynamic theory of the helical gear drive is investigated, and corresponding dynamics equations are derived. Based on parameterized language APDL of ANSYS, a parametric programming module for accurate modeling and automatic assembling of helical gear pair has been developed. The parametric modeling and transient dynamic analysis of a helical gear pair in a crane reducer are performed. Transient stresses and strains of the gear pair throughout the engagement process are obtained and the worst meshing location can be determined. Compared to the traditional static analysis, Simulation results of dynamic analysis are more accurate and reliable which provide the foundation for accurate estimation of the gear fatigue life.