Papers by Author: Bo Zhao

Abstract: In this paper the relationship of the efficiency of ultrasonic grinding and abrasive movement are studied. Ultrasonic grinding grain three-dimensional trajectories were simulated based on MATLAB software in the paper, and micro-grinding surface states were observed with SEM. Therefore, the influence law of ultrasonic vibration to the grinding surface texture is received. The results show that: Compared with ordinary grinding, the workpiece grinding surface texture quality and the grinding efficiency have been significantly improved under the condition of ultrasonic vibration.

Abstract: In this paper, five kinds of power ultrasonic transducers with different section plane positions are designed and the shapes of the transducers are straight. The different section plane position changes with the length l2 of front cover. That is to say, the longer l2 is, the more front the position of the section is. The experiment indicates the great influence of the section plane position on the transducer performance.With the increase of the length of the front cover, the dynamic resistance reduces gradually, and the resonance frequency and the anti-resonance frequency also reduce. Under this condition, the anti-resonance frequency declines more sharply, and the mechanical quality factor increases gradually, but the effective mechanical and electrical coupling coefficient reduces gradually. The transducer has different measure targets in different situations. Therefore, different parameters may be primordially considered to be designed according to the actual use of the transducer in this paper. This provides the reference for manufacture and use of transducers.

Abstract: The brittleness, plasticity, super-plasticity and the removal mechanisms of critical fragmentation of the nano ZrO2 ceramics were investigated. The formula of critical ductile grinding depth of the common engineering ceramics was inapplicable to the nano-ZrO2 ceramics. A new formula of critical ductile grinding depth of the nano ceramics was established. The ultrasonic vibration grinding experiments showed that the critical ductile grinding depth of the ceramics was 15μm by conventional grinding, but the increment of the critical ductile grinding depth was 60 percent by ultrasonic grinding. The critical ductile grinding depth increased to 25μm. Analyzed by means of SEM, it was transgranular cracking during its cracking process. The nano-ZrO2 ceramics have high toughness so the critical ductile grinding depth increased. The shape, length, width and thickness of the grindings differed greatly from which obtained by conventional grinding.

Abstract: In this paper, the edge quality of the nano-ZrO2 ceramics surface grinding was studied on experiments. Through the microscopic observation and measurement on the edge micro-step，and the white interference detection on the 3D surface profile of both sides of the edges, the edge quality traits are obtained，which lay a foundation for further study on the technology of the edge quality controlling and hard brittle material surface integrity evaluation.

Abstract: Hydraulic engine mounts (HEMs) are important vibration isolation parts in vehicle powertrain mounting systems, and the structural parameters of HEMs are the main factors which determine their vibration isolation characteristics. It is of great significance to discover the influences of the structure parameters on their vibration isolation characteristics in the design and study of HEMs. Firstly, the vibration isolation characteristics of HEMs are analyzed theoretically using a simplified lumped parameter (LP) model. Secondly, the HEMs with different rubber materials, lengths and cross-sectional areas of the inertia tracks are designed and manufactured, and their frequency response characteristics are investigated by experimental and analytical methods. Finally, the influences of these structural parameters on the vibration isolation characteristics of HEMs are educed. The analytical methods and conclusions are instructive for the design and tuning of the vibration isolation characteristics of HEMs.

Abstract: The Large-grit bronze-bonded diamond grinding wheel was shaped employing a diamond dresser with elliptic ultrasonic vibration assistance, to solve problems such as high cost, low dressing speed and low accuracy. And the truing and conditioning performance of this new method was discussed for its effectiveness. Experimental results showed that the roundness error of elliptic vibration dressed diamond grinding wheel is less, and the bond tail was cut shorter and the chip capacity became larger than that of mechanical dressed one. The SEM observation showed for the present dressing method the material removal mechanism is ductile removal of bond material and micro breakup of gains and this method can perform truing of large-grit diamond grinding wheel as well as conditioning in one step.

Abstract: The application of ultrasonic polishing and machining pulse electrochemical machining compound finishing is presented in the paper. The machining principle and experimental set-up of UPM-PECM compound finishing are introduced in the paper, discussing mechanism and model of the UPM-PECM in theory, and carrying on the experiment, which would co-act on hard-brittle metals in the machining. Furthermore, the material removal depth of UPM-PECM compound finishing is approximately proportional to the polishing time, and would decrease with the polishing time. This study indicates that machining velocity, machining accuracy and surface quality can be improved under UPM-PECM.

Abstract: In order to solve the difficulty of on-line measuring the surface roughness of workpiece under ultrasonic polishing, the artificial neural networks and fuzzy logic systems are introduced into the on-line prediction model of surface roughness. The surface roughness identification method based on fuzzy-neural networks is put forward and used to the process of plane polishing. In the end, the on-line prediction model of surface roughness is established. The actual ultrasonic polishing experiments show that the accuracy of this prediction model is up to 96.58%, which further evidence the feasibility of the on-line prediction model.

Abstract: In this thesis, the atmospheric pressure nitrogen dielectric barrier discharge (DBD) plasma modified polyproylene (PP) melt blown non-woven surface wettability are investigated. The change of surfaces physical and chemical properties are studied by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) before and after plasma treatment. The experimental results indicate the surface hydrophilic can be greatly improved when the PP simples is treated by atmospheric pressure nitrogen DBD plasma for a short time. And a large number of oxygen-containing and nitrogen-containing functional groups are inplanted on the PP non-woven sample surface.

Abstract: Ultrasonic-vibration hard cutting (UVHC) is a advanced technology, where high- frequency vibration is superimposed on the movement of the cutting tool. Compared to conventional turning (CT), this technique allows significant improvements in processing hard-to-cut materials, by producing a noticeable decrease in cutting forces and a superior surface finish. The paper presents a finite-element model of both CT and UVHC. Stresses produced in workpiece and cutting forces acting on the cutting tool in UVHC are studied, and the influence of cutting parameters, such as cutting speed and cutting depth on cutting force are investigated.