Papers by Author: Bo Zhao

Abstract: The ultrasonic-assisted single-grit grinding device is designed which can be used to efficiently simulate grinding process, and the comparative tests of single-grit ultrasonic grinding are carried out between Nano-ZrO₂ ceramics and ZTA ceramics under different grinding depth. The experimental results show that the bigger the scratch depth was, the greater damage degree of material was, nano-ZrO₂ ceramics’ grooves is smoother than that of ZTA ceramics and the damage of its material is minor; ultrasonic vibration broadens the range of plastic cutting of Nano-ZrO₂ ceramics in some degree. The experimental phenomena also show that the rolling role of abrasive particle can be conducive to material plastic deformation.

Abstract: Based on nonlocal theory, The effects of ultrasonic frequencies on the grinding force and nonlocal decay rate are obtained through the experimental study of material properties under ultrasonic vibration grinding test. The results of experiments showed that grinding force is attenuated in the ultrasonic vibration frequency ranges and this attenuation phenomenon becomes more and more evident by the increase of the ultrasonic frequencies. Through analysis of the grinding surface morphology and phase structure, it showed that ultrasonic vibration greatly reduces the average grinding force, and the surface quality are improved, and that it is much easier to achieve ductile-mode machining under ultrasonic vibration. The results of experiments are in accordance with the analysis of nonlocal theory.

Abstract: The effects of the cutting parameters on residual stresss were investigated in common and ultrasonic vibration hard turning bearing steel GCr15 with PCBN. The residual stresses under the machined surface were measured by X-ray diffraction technique. The results obtained in this study show that residual compressive stress is produced both in common and ultrasonic turning of GCr15 bearing steel. Under the same turning condition the residual compressive produced by the ultrasonic turning is smaller than that by the common turning. Residual compressive stress can improve the fatigue performance and life of workpiece, so the cutting parameters should be optimized to get the best residual compressive stress in ultrasonic turning.

Abstract: In processing of structure ceramics materials with diamond grinding wheel, grinding heat is one of vital factors influencing workpiece surface quality. Grinding parameters have important influences on workpiece surface temperature distribution. Contrast experiments on grinding temperature field of ZrO2 in common and ultrasonic grinding were carried out in the paper by manual thermocouple method. The relationship between grinding parameters and temperature were researched theoretically and experimentally. The results show that the farther the distance from grinding surface, the smaller the peak value of temperature is. With the increases of grinding depth, grinding speed and feedrate, the surface temperature will heightens accordingly. It was proved that grinding depth is the most vital factor influencing grinding temperature field through orthogonal experiments. Furthermore, comparing with high surface layer temperature which often results in grinding burn in traditional grinding, ultrasonic grinding can reduce grinding temperature effectively.

Abstract: The orthogonal analysis and single factor analysis were used to analyze the roughness of SiCp/Al metal matrix composites (SiCp/Al MMCs) with ultrasonic high-speed milling and high-speed milling. The influences of milling speed, feed and milling depth on the roughness were studied. The research indicates that the roughness in ultrasonic high-speed milling is lower than that in high-speed milling under the same condition, at the same time the optimal parameters of ultrasonic high-speed milling are obtained, this has a guiding significance for finish machining of SiCp/Al composites.

Abstract: Carbon fiber reinforced plastics (CFRP) have been used widely in airplanes, spaceships, automobiles and sport equipment, etc. But the machining is very difficult due to the rigidity of its internal reinforced-phase. In order to settle the difficult machining problem of CFRP, ultrasonic vibration is introduced to common cutting. Through the experiment of common milling and ultrasonic milling of CFRP, the influences of different parameters on milling force are studied. The experimental results shows that the milling forces of ultrasonic milling are significantly lower than common milling using the same milling parameters. The processing vibration of ultrasonic milling is lesser and the process is more stable than the common milling.

Abstract: Physical and mechanical properties as well as microstructure of zirconia toughened alumina ceramics with different zirconia content were tested. The results show that the best physical and mechanical properties are obtained in sub-micron composite ceramic when zirconia content is 25%; while the physical and mechanical properties of nano-zirconia toughened alumina ceramics are far better than those of sub-micron zirconia toughened alumina ceramics. Therefore physical and mechanical properties of ceramics can be improved significantly by adding proper amount of zirconia into alumina matrix and refining zirconia particles.

Abstract: Based on the research on the quality of grinding surface of engineering ceramics, the engineering materials can be widely used. The ultrasonic grinding surface of the ceramic plate is discussed in this paper by dividing regionally. Concentrating on how the edge quality affects the surface topography, the white-light interference measuring techniques is used to observe the topography of the grinding surface.

Abstract: Although particle reinforced metal matrix composites possess excellent physical properties, its machining performance is rather bad because of its specific structure. It is difficult to obtain good cutting effect by traditional machining method. So machining has become the bottleneck which strictly restricts its industry application. This paper mainly focuses on both wear characteristics of different tool materials and material removal mechanism in ultrasonic milling high volume fraction particle reinforced metal matrix composites SiCp/Al. An acoustic device for ultrasonic vibration milling was developed to introduce the ultrasonic vibration into the traditional machining process. Through the contrast experiment of traditional milling and ultrasonic vibration milling SiCp/Al, the mechanism of tool wear and characteristics of surface topography were analyzed. The experimental results showed that the surface integrity and tool life in the ultrasonic vibration milling SiCp/Al were improved. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: In this paper, on the influence of different dressing methods, such as elliptical ultrasonic vibration, on the grinding wheel bonded delta, the morphology of abrasive grains of wheel, the protrusion height and the grinding wheel topography was studied by experiment. The experiment shows that the abrasive grains of grinding wheel surface dressed by elliptical ultrasonic vibration are great in protrusion height and trench depth, and the bonded delta grain after grinding is narrow, short, and irregular with significant reduced semi-surrounded area compared with by ordinary dressing method. The abrasive grains of metal-bonded diamond grinding wheel surface dressed by elliptical ultrasonic vibration are basically intact, and due to the high-speed collision between abrasive grains, local micro-break is easy to occur on the abrasive grains to form multiple micro-cutting edges. The abrasive grains of grinding wheel surface dressed by ordinary dressing method are fractured and broken, while that of resin-bonded grinding wheel surface have a high ratio to be loose and shedding. For the metal or resin-bonded grinding wheel surface dressed by elliptical ultrasonic vibration, its material removal mechanism may primarily be the removal of bonding ductility and the fine-crushing of abrasive grains; for the metal-bonded grinding wheel surface dressed by ordinary method, its material removal mechanism may primarily be the fracture and break of abrasive grains, secondly be the fracture of bonding agent; and for the resin-bonded grinding wheel surface, its material removal mechanism may mainly be the looseness and shedding of abrasive grains caused by the fracture of bonding agent, secondly be the fracture of abrasive grains. Compared with ordinary dressing method, elliptical ultrasonic vibration dressed abrasive grains are dense at shaft and sparse in periphery, with a large quantity of static effective abrasive grains, great protrusion height and an excellent nature of contour.