Papers by Author: Ming Wang

Abstract: The normal circular arc bevel gears are used in industrial areas of high speed, high bearing and high strength widely. A mathematical simulation model is built and it can analyze transmission error and contact zone of normal circular arc bevel gears. In this model, the instantaneous engaging points of gear pair are transformed into the least-values of rotary angles of corresponding points between two gears along the final motion, so this method is very simple and effective. Under the condition of existing helix angle error, transmission error and contact zone of a pair of normal circular arc bevel gears are simulating analyzed. At last, the operation test of contact zone of gears indicates gears transmission is stable and the gears contact zones are largely in line with the simulation results.

Abstract: The performances of particle reinforced aluminum matrix composite is excellent, but it is hard to be manufactured, which resist its wide spread engineering application. Rotary ultrasonic machining (RUM) is very suit for machining of particle reinforced aluminum matrix composite with moderate or high volume fraction. An aluminum matrix composite reinforced with 45% volume fraction of 3μm silicon carbide particles in a A12 aluminium matrix is experimental studied by RUM, and surface topography, surface roughness and cutting force are analyzed. The experimental results show that machining surface quality is high, surface roughness Ra ranges from 0.131~0.340μm, the cutting process is very smooth and cutting force Fz ranges from 23.33~51.31N, grinding wheel jams and grinding burn do not appear on rotary ultrasonic cutting tool after machining, and tool wear is extremely little.

Abstract: Based on the field and lab measuerement in harvest time, Physical and mechanical properties of fritillaria ussuriensis maxim (FUM) are researched. Geometrical properties of FUM are analyzed using mathematical statistics method, and the variation sections of main index values of two kinds of FUM are obtained. Mechanical properties of FUM outsifting in screen penetrating process are tested by means of friction experiment, the friction coefficient and angle of repose of two kinds of FUM are obtained using mathematical statistics method. Grade sieve machine is designed based on the analysis of mechanophysical properties of FUM. The main parameters are: shape of sieve pore is rectangle, screen diameter is 20mm, sieve pore dimension of upper layer is 13×20mm2, middle layer is 9×18mm2, and under layer is 7×10mm2. By testing of friction coefficient and angle of repose and movement and dynamics analysis of grade sieve, outsifting velocity is 7<<9rad/s and acceleration is 4<a<13m/s2 in screening process.

Abstract: SiCp/Al thin-walled structure is processed by rotary ultrasonic machining (RUM). Machining allowance of thin-walled structure is large, manufacturability is bad, and it is vulnerable to vibration to reduce processing quality in machining. Based on analysis of chatter mechanism of RUM, a dynamic model for chatter analyzing and a stability judgment criterion are established and the simulation is conducted for a typical thin-walled component of SiCp/Al composite with time domain analysis method. The simulation results show that machining parameters of RUM could be optimized selected with this model, chatter could be prevented effectively and a good processing effect achieved.

Abstract: Thin-walled workpieces have the characteristics to withstand a greater load with less material and they are used in aerospace field widely. SiC_p/Al composite has high strength and stiffness, which meets the requirements of the aerospace workpieces well. The optimization method is studied with grinding stability and material removal rate as constraint conditions in this paper. The processing parameters optimization of a SiCp/Al thin-walled cylinder is analyzed according to stability lobe diagram. The grinding parameters optimization could be achieved by this method and the chatter could be prevented effectively.

Abstract: Particle reinforced aluminium matrix composites could be used in manufacturing of aviation thin-walled workpiece due to its excellent performances, but it is hard to be manufactured. Rotary ultrasonic machining (RUM) is very suitable for machining particle reinforced aluminum matrix composites with moderate or high volume fraction. Chatter appears very easily in machining process of thin-walled workpiece and it can seriously reduce the quality of components. Based on the dynamic characteristics of machining process, a stability analytical model is built. It is analyzed that the process stability of a thin-walled workpiece of SiCp/Al composites reinforced with 45% volume fraction, and the stability lobe diagram is plotted by using MATLAB. According to stability analysis results, a machining experiment is conducted and the test results indicate chatter could be prevented effectively by this method.

Abstract: In order to investigate the influences of machining parameters on surface roughness in ultrasonic vibration mill-grinding, the motion of abrasive grain is analyzed. The analysis indicates that grain and workpiece separate periodically which are beneficial for coolant entering into grinding zone to reduce grinding temperature and grinding force and improve surface quality. Experiments are carried out and detected by SEM and roughmeter, the results indicate that influences of spindle rate, feeding speed, cutting depth and amplitude decrease in turn. Through regression analysis, an empirical formula is obtained. The experiments indicate that material removal mode dominates surface roughness.

Abstract: In order to investigate material properties of silicon nitride ceramic, nanoindentation tests are carried out on Hot-press silicon nitride specimen. The micro-hardness and elastic modulus are obtained. simultaneously, load-displacement curve is acquired. The whole process is simulated in ansys. Through comparing, there are satisfactory consistency between experimental curve and simulation curve. In addition, simulation can also indicate the distribution of stress fields during loading and unloading process. Base on these informations, the mode of cracks development and mechanism of material removal can be known.