Papers by Keyword: Vitrified CBN Wheel

Abstract: Laser triangulation was used to measure the topography of vitrified CBN wheels and optimum sampling interval was obtained by comparing measuring results with different sampling intervals. Four evaluation indexes including the mean protrusion height of abrasive grains Hm, the standard deviation of grain protrusion height Hv, the standard deviation of the distance between two adjacent grains Dv and the number of micro cutting edges per square millimeter Nm were put forward to assess wheel topography and grinding performance. These indexes were verified to be effective by comparing 3D topography of newly manufactured wheel and dressed wheel.

Abstract: Titanium alloys have been widely used in aerospace and manufacturing industry because of their unique high strength-weight ratio, fracture resistance, and superior resistance to corrosion. In this paper, a series of experiments were carried out to research the surface integrity in grinding Titanium alloy TC11 on a milling centre with small vitrified bond CBN wheel. Nine runs involved in the orthogonal array are designed in accordance with three factors at three levels. The surface roughness Ra 0.72 um and Rz 4.73 um are obtained. Subsequently ANOVA is employed to analyze the relative importance of all control factors on surface roughness and the optimal combination of grinding parameters is gotten. The measurement of microhardness is also taken and the microhardness profile is then drawn. The metallographic analysis shows that a plastically deformed layer are formed beneath the ground surface at 0~80 um and no white layer is observed. Experimental results validate the feasibility of grinding Titanium alloys on a milling machine with a small vitrified CBN small wheel.

Abstract: This paper investigates the effect of the CBN abrasive types, sizes, concentration, bond amount, and porosity of a vitrified-bonded CBN wheel on grinding ratio, grinding forces, and surface roughness of grinding hardened steels. The experiment results showed that during grinding hardened steels the amount of bond with increase of the depth of cut increased, which makes the wheel to have a better bonding strength to get a better grinding ratio and surface roughness of the workpiece. The grinding forces produced increased with the increase of the depth of cut. In addition, too much porosity of a vitrified CBN wheel will cause the low bond strength, leading the wheel to wear rapidly. Hence, to obtain a higher grinding ratio and better surface roughness of the workpiece during the grinding hardened steels should select relatively a higher amount of bond, a lower porosity, and a higher grit strength and concentration, but the grinding forces produced were relative higher.

Abstract: This paper focuses on experimental investigation on high speed grinding of 40 Cr steel with vitrified CBN grinding wheel, the effect of grinding process parameters, such as grinding speed, depth of cut, and feed rate, on the grinding force and surface roughness are analyzed The experimental results reveal that the grinding force decreases with higher grinding speed and increases with the addition of depth of cut or feed rate, and the surface roughness is satisfactory in high speed grinding.

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: This paper aims at the development of an alterative technique for truing and dressing a small vitrified CBN grinding wheel used for the internal finishing of small holes measuring several millimeters in diameter. In conventional truing and dressing, a single-tip diamond dresser or a rotary GC cup wheel dresser is employed. This levels off the improvement in the wheel truing accuracy because the stiffness of the grinding wheel shaft with an open-sided structure is low, and the shaft is thus deformed easily due to the truing force. In the present work, a new truing and dressing technique is proposed in which a Nd:YAG laser beam is employed as the dresser. Experiments were carried out with respect to the effects of the laser beam conditions (amplitude, width and frequency of pulse, and focus offset) and the relative motion between the laser beam and CBN wheel. It was found that the run-out of the CBN wheel was decreased significantly, and the wheel surface condition was improved greatly after laser truing and dressing.