Advanced Materials Research Vols. 53-54

Abstract: In this paper, grinding performance and Manufacturing process of vitrified CBN wheel were described for Quick-point grinding at 200m/s. In order to insure security rotation of wheel, wheel core was optimized at 200m/s based on ANSYS software. Four kinds of domestic abrasives were tested for their compressive strength, impact toughness, microcosmic crystal photographs, and oxidation temperature, high temperature performance baked at 870 °C, by right of advanced apparatus such as SEM etc. Simultaneity vitrified bonds, wheel segments and adhesive techniques were also discussed. At last, grinding performance of Quick-point Grinding wheel was tested.

Abstract: The influence of ultrasonic vibration on the surface roughness and micro-topography of ceramics plate is discussed in this paper. Grinding assisted by two-dimensional ultrasonic vibration is developed to deal with the processing difficulty of ceramic materials due to its hard-brittle property. The experimental results show that the surface roughness value obtained in two-dimensional ultrasonic grinding nano-ZrO2 ceramic plate specimen is obviously smaller than that in common grinding, and the scratched grooves on the machined surface in ultrasonic grinding is wider and relatively smoother than that in common grinding. Consequently, it proves that the two-dimensional ultrasonic machining is a feasible, high-efficient machining method for hard-brittle materials.

Abstract: With more attention paying to the environment, green manufacturing (GM) has become inevitable trends in 21st century. Green cooling technology as one branch of GM always was one research hotspot in manufacturing. In this paper, a new high efficiency cooling technology based on GM is proposed, called as CPMJ. In this technology, a little quantity of 0 °C water is carried by high pressure cryogenic air (–20 °C) and reaches the grinding zone in the form of high speed mist jet to enhance heat transfer and gain the best cooling effect. Heat transfer experiments and grinding experiments were carried out to evaluate the cooling effects of CPMJ. Experimental results indicated that CPMJ can offer better cooling effects compared with cold air jet and flood cooling method. Grinding temperature was effectively reduced during grinding of titanium alloys with CPMJ.

Abstract: A novel truing and dressing method, namely fiber laser assisted truing and dressing diamond wheel, is proposed to overcome the shortcomings associated with conventional mechanical dressing methods, ELID and ECD methods. A series of experiments have been conducted to prove that it achieves both high truing efficiency and good dressing quality. The finite element analysis of temperature distribution in fiber laser assisted truing and dressing diamond wheel using ANSYS is performed by author. Temperature field simulation helps to select optimized parameters under certain conditions.

Abstract: This paper is principally concerned with the form error measurement and evaluation of the spherical surface after precision machining. According to the minimum zone condition, the definition of sphericity error is first analyzed. To obtain the minimum sphericity error from the form data, an approximations technique is devised. First the method is modeled, then the process of approximations is constructed, and finally software for data processing is programmed. Six steel bolls of φ50 are measured on a coordinate measurement machine (CMM) in the Measurement experiment. The experiment results indicate that the geometric approximations technique can give an accurate solution with high efficiency.

Abstract: Among the properties of polishing pad, the surface roughness plays a crucial role in CMP (Chemical Mechanical Planarization) process. However, there is no acknowledged standard for measuring and characterizing the roughness of pad surface in 3D measurement. In this paper Talysurf CLI 2000 working on the principle of dynamic confocal measurement was initially suggested to measure the 3D surface topography of polishing pads through theoretical and experimental analysis. In addition, based on the Nyquist folding frequency and the statistical theory, a selection technique for sampling interval and sampling area was proposed and verified through experiments. The results showed that Talysurf CLI 2000 is more suitable than NewView to measure the 3D surface topography of polishing pads. 2μm sampling interval, 0.5×0.5mm2 sampling area and 10μm interval, 1×1mm2 area are respectively recommended for IC1000/SubaIV and SubaIV polishing pad.

Abstract: Because of its high machining efficiency and good machining quality, ultrasonic aided high-speed lapping with solid abrasive is regarded as a good method of cylindrical machining for engineering ceramics. Compared with conventional lapping, ultrasonic aided high speed lapping has unique surface topography distribution characteristics for the difference of the surface formation mechanism and material removal mechanism. In the paper, the surface topography characteristics of engineering ceramics in different lapping mode were researched. Research results show that the lapped surfaces with and without ultrasonic assistance present different surface topography characteristics. Under the same lapping mode, the lapped surface topography is distinctly different for different ceramics. With the assistance of ultrasonic vibration, more ductile material removal can be obtained and the surface quality can be improved correspondingly.

Abstract: White layer formed in the machined surface has been observed in many manufacturing processes. However, grinding has been considered more sensitive to form white layer due to the characteristics with high temperature and rapid heating and quenching. As an effective process to the difficult-to-machining die steel, grinding is widely used in the finishing of die and mould components with high precision. So study on white layer formed in ground surface is significant to improve the product quality and life. In this paper, grinding experiments focus on SKD-11 hardened steel with variable parameters were conducted to study the white layer formation and the parameter optimization to develop the favorable white layer and restrict the thickness of the dark-etching layer and the hot-affective region.

Abstract: The properties of the white layer in the surface grinding are described. The influences of heat treatment, carbon content and grinding conditions on the white layer formation are discussed. It is found that the white layer in the hardened steel is thicker and harder than that in the annealed steel, and there is not a softer transition zone in the annealed steel. Higher carbon content tends to increase white layer thickness at the larger cutting depth, while no difference is observed at the smaller cutting depth. Increased carbon content tends to increase white layer hardness. The white layer thickness increases as the cutting depth increases. The white layer thickness increases with the rise of the table speed until a certain critical speed value is reached, beyond which the white layer thickness decreases with the increase of the table speed. The white layer in the central zone of the workpiece is thicker than that in the entrance zone, but it is thinner than that in the exit zone.

Abstract: Invar 36 alloy is widely used in manufacturing instruments because of its minimal thermal expansion coefficient. As an important material for the components of precision or super-precision instruments, the process methods for Invar and the structure stability after its machining is necessary. In this paper, the residual stresses of the Invar samples after plane grinding were measured. The experimental results indicate that clear tension stress exists in the surface of Invar alloy along the grinding direction, while, on the cross direction, the states of surface residual stresses are complicated and affected by the parameters of grinding. A typical disk model has been calculated and analyzed by Finite Element Method (FEM), and the deformation caused by surface residual stress was presented. Finally, the effect of grinding as final working procedure on the stability of Invar structure was estimated.