Papers by Author: Hui Huang

Abstract: The effects of the geometric parameters of a sawblade on the sawing fluctuated temperatures were analyzed based on a fluctuated temperature model advanced in my recent paper. The results show that the sawing temperatures are fluctuated only near the workpiece surface in the sawing zone, the blade segment ratio, the number of segments and the contact angle have great influence on the sawing temperatures, which has the guiding significance for optimal design of the sawblade structure.

Abstract: An investigation was undertaken to explore the specific energy and material removal mechanisms involved in the grinding of cemented carbide with vacuum brazing diamond wheels. A mathematical model, relating to the grinding parameters such as wheel velocity, workpiece feedrate and depth of cut, was proposed to predict specific grinding energy, and was verified by experimental data. This verification came as a result of surface grinding two typical cemented carbides (YG8 and YG30) with a vacuum brazing diamond wheel under various grinding conditions. The earlier model’s prediction shows a direct correlation with the experimental results. Good relationships between the consumed power per unit width with the plowed face areas generated by all cutting points per unit width were obtained. Microscopic examination of the ground surfaces and the grinding detritus by a digital and video microscope system also revealed that material removal occurred mainly by flow-type chip formation (plastic flow) while grinding YG8 and by blocky fracture particles formation (brittle fracture) while grinding YT30.

Abstract: In order to assess the bonding of brazing alloys to diamonds, an investigation was conducted to measure the forces while shearing brazed diamonds. A device was designed to shear diamonds and shearing forces were recorded under different brazing parameters. The morphologies of diamonds were followed before and after shearing. It is found that the shearing force reduces with the increase of grit protrusion height. For specific grit protrusion, shearing forces decrease with the increase of holding time in brazing.

Abstract: An investigation is reported on the temperature in grinding of titanium alloy (TC4) by using a vitrified CBN wheel at grinding speed up to 120m/s. The temperatures under different grinding parameters were measured by using a sandwiched foil thermocouple. Coupled with the SEM observations on the ground workpiece surfaces, characteristics of temperature in high speed grinding were analyzed and compared with the temperatures in grinding at normal speeds. It is found that grind speed is the most significant factor to determine temperatures, which might be associated with the increase of material removal in the plastic way at higher grinding speed.

Abstract: The effects of cutting parameters on the transverse vibration of diamond circular saw blade were experimentally investigated. Transverse vibration was online measured by a novel measuring system developed by wireless sensor. Meanwhile, axial force on saw blade was measured by a dynamometer. By the experimental results under different cutting parameters, the time domain characteristics of transverse vibration of saw blade were analyzed, and the relationships between transverse vibration and cutting parameters were also obtained. Axial deformation is greatly influenced by the axial force acting on saw blade.

Abstract: An experimental investigation was carried out to braze diamond abrasives onto thin steel wires, in which case the brazing was conducted in the vacuum and under high temperatures by using a nickel-based powder as brazing alloy. The morphologies and microstructures of the brazed wires were observed and the comprehensive mechanical properties of the brazed wires were tested. The brazed wires were also used to cut such brittle materials as ceramics, glass, and natural stone. It is shown that a typical phenomenon of brazing alloy’s climbing around the diamond grains was observed in brazing the wires. Through observing the cross-section of brazed wires, it is observed that there is a good bonding between the brazing alloy and the body of steel wires. The crystal grains of the steel wires grew significantly after brazing. Through observing the morphologies of the diamond wires and the surfaces of four workpiece materials, few diamond pull-outs were found on the wires and the kerfs on the workpiece materials were basically flat.

Abstract: Grinding forces, protrusion height, grinding temperatures and wear of diamond grits have been studied in grinding cemented carbide YG8 with a single-layer vacuum brazed diamond wheel. The experiment results indicate that the primary wear progression of diamond grits in the whole grinding process follows the mode of whole diamonds, flat diamonds when grinding of the cemented carbide. The worn mechanism of the failure of diamond grits was discussed and possible solutions are recommended. The proportions of diamond conditions and the mean protrusion height of grains are more closely related to grinding forces and grinding temperatures. The grinding forces, force ratio and grinding temperatures decreased with the increasing proportions of whole crystal and the decreasing mean protrusion height of diamond grits, and the tangential and normal force components increased with the gradual wear of the brazed diamond wheel during a long-time grinding process. It shows great potential in improving thermal damage of cemented carbides by reduces grinding temperature with vacuum brazing diamond wheels.

Abstract: The wear of a brazed diamond wheel with diamond grits covered with brazing alloy was investigated in comparison with a traditional brazed wheel whose grits were without covering. The two wheels were brazed in vacuum furnace and grits on one of them were overlaid with a thin layer of brazing alloy. The wear of the two wheels was tested through grinding of granite, during which grinding forces were measured and the wear states of diamond grits were observed. It is shown that grits covered with brazing alloy exhibited stronger self-sharpening ability and fracture resistance. Therefore, the wheel with covered diamonds performed lower grinding force and better wear performance.

Abstract: The background temperatures in the sawing of granite with a diamond wire were measured by foil thermocouple. The influences of the measuring position in the cutting zone, cutting speed, feed rate and coolant on the temperature were investigated. The results indicated that the background temperature would be stable after a short-term rise. It was shown that the background temperature increased with cutting speed, but there was no obvious relationship between the background temperature and feed rate. The maximum background temperature appeared at the front part of the cutting zone at a lower feed rate. With an increase of feed rate, the background temperature at the middle of the cutting zone was the highest. The coolant had an obvious influence on the maximum background temperature.

Abstract: An investigation was undertaken to elucidate the mechanisms for the fracture failure of brazed diamonds in wire sawing. Diamonds were brazed by high-frequency induction in vacuum. The changes of compressive strength and the appearances of the diamonds at different brazing temperatures were obtained. The morphologies of the diamonds after sawing were also observed. Together with the stress analysis of a brazed grit, it is found that the fracture failure of brazed grit is the result of the brittle fracture happening on the root section of the grit, the interface between the grit and the brazing alloy. The degradation of mechanical properties of grits in brazing is a key factor to the reduction of their resistance to fracture. Lower machining forces as well as grit exposure are in favor of preventing grits from fracture.