Papers by Author: Yu Can Fu

Abstract: This article studies the forces and tool wear behavior in the milling process of Ni₃Al-base superalloys with cemented carbide cutting tools. The effects of cutting parameters on the machinability of these superalloys are experimentally discussed. The results indicate that the forces increase with the increase of the axial depth of cut, the radial depth of cut and the feedrate per tooth. The cutting tools wear rapidly in the milling process of Ni/Al superalloys. The cemented carbide cutting tool with TX coating is more suitable for machining Ni/Al superalloys when compared with the tool with TiCN coating.

Abstract: This paper presented a numerical model of a grinding wheel hub to analyze the dynamic behavior between CFRP hub and steel hub. Natural frequencies of the two different hubs were extracted with the help of finite element software ABAQUS. In addition, the vibration attenuation procedure in the process of free vibration of the hubs was also compared. The numerical results obtained from the model demonstrated that natural frequency of the CFRP hub is much higher than that made of steel owing to the great ratio of elastic modulus to density of carbon fiber. The CFRP hub has a better damping vibration characteristic which allows it to absorb vibration in grinding process to achieve a finer surface roughness.

Abstract: An experimental study on milling of Invar36 was conducted by using coated carbide insert to characterize the cutting force. The Taugchi's design of experiment was used for experimentation and the cutting force regression equation was established based on the principles of probability statistics and regression analysis. The results showed that the cutting force was significantly affected by the axial depth of cut and the feed per tooth, and with the increase of the axial depth of cut, the cutting force increased very quickly. Compared with the axial depth of cut, radial depth of cut and cutting speed had less influence on the cutting force. The established regression equation was highly reliable.

Abstract: Single-grain grinding test plays an important part in studying the high speed grinding mechanism of materials. In this paper, a new experimental system for high speed grinding test with single diamond grain is presented. The differences of surface topography and chip morphology of Inconel 718 machined by single diamond grain and single CBN grain were evaluated. The grinding forces and corresponding maximum undeformed chip thickness were measured under different grinding speeds. The chips, characterized by crack and segment band feature like the cutting segmented chips, were collected to study the high speed grinding mechanism of nickel-based superalloy. The results show that the grinding speed has an important effect on the forces and chip formation, partly due to the temperature variation. As the speed increases, the groove surface becomes smoother.

Abstract: This study describes the theoretical basis of ultra-high-speed grinding. In addition, a new grinding machine tool whose maximum grinding speed can reach 450m/s has been recently developed, particularly, some of main components are basically discussed. Finally, this paper concludes with a presentation of current work and some future desirable plans in the area of ultra-high-speed grinding by means of the developed grinding machine tool.

Abstract: Titanium matrix composites (TMCs) possess many outstanding properties and have increasing and potential application in aerospace, automobile and other industries. However, TMCs are typical difficult-to-machining material due to the rapid tool wear rate and excessive machining induced defects. In this paper, tool wear, cutting forces, cutting temperature and surface roughness were investigated when milling TMCs with Polycrystalline Diamond (PCD) and carbide tools. The results showed that the values of surface roughness obtained by carbide tools were higher than that of PCD tools under the same cutting conditions. The value of cutting temperature for PCD tool was about 75% of the carbide tools, and the main cutting force value of PCD tool was about 85% of the carbide tool. Abrasive and adhesive wear were the main wear mechanisms of PCD and carbide tools. In all, PCD tools had a better cutting performance than carbide tools during finishing milling titanium matrix composites.

Abstract: Ti2AlNb-based alloy is regarded as lightweight high-temperature structural material, which is expected to replace the nickel-base super alloy due to its low density, high elastic modulus, strength retention at elevated temperature, outstanding oxide resistance. However, these excellent properties also make Ti2AlNb to be difficult-to-cut material. In this paper, the milling experiment of Ti2AlNb alloy was carried out using Ti(N,C)-Al2O3 coated cemented carbide tools. SEM and EDS analysis was utilized to observe the worn tools to determine the tool failure modes and wear mechanisms. Tool life when milling Ti2AlNb was short and heavily dependent on the cutting parameters. During milling, coating material of the tool was separated rapidly from the base material. When the cutting speed exceeded 100m/min, serious cracks appeared on the tool surface. Thermal fatigue, adhesive and attrition were the predominant wear mechanisms of the coated tools.

Abstract: An investigation is reported of the effect of grinding speed on energy partition for grinding of Inconel 718 with virtrified CBN wheels. Temperature was measured in the ground surface of Inconel 718 with semi-natural thermalcouple. The energy partition and heat flux distribution within the grinding zone were estimated and analyzed. The result indicates that low energy partitions were found to be convected into the workpiece and wheel, both were lower than 10%, and the energy partition into the coolant decreases greatly from 75% to 25% while the one into the grinding chips increases from 15% to 70% with the increasing speed.

Abstract: Aiming at the deficiency of existing focused ultrasonic technology, a new high-power Spherical Shell Focused Ultrasonic Transducer (SSFUT) was designed. The SSFUT is composed of a sandwich piezoelectric ultrasonic transducer and a bending vibration spherical shell. Simulation on acoustic field of SSFUT was carried out. the acoustic field pressure distribution nephogram and the axial acoustic pressure curve of the SSFUT were obtained. The consistency of finite element simulation results and experimental results was verified by testing. The research provides a theoretical basis for implementation and application of the new focused ultrasonic technology.

Abstract: Ti-6Al-4V alloy was hydrogenated at 800°C by thermohydrogen treatment technology. Sliding friction and wear tests were carried out in a special tribometer assembled on CA6140 turning lathe to investigate the friction and wear morphology between hydrogenated titanium alloys and WC-Co cemented carbides. The morphological analyses of the worn surface were made by scanning electron microscope. It was found that the friction coefficient and the friction area temperature of the pair both firstly decreased and then increased with the increase of hydrogen content, and the friction coefficient decreased and the friction area temperature increased with increasing sliding speed. The main wear morphologies of the unhydrogenated alloys were serious plastic deformation, ploughing, adhesion tearing pit and fatigue microcrack, but the main wear morphologies of the hydrogenated alloys were boundary of plastic extension, slight scratch and slight adhesion tearing. Besides, the main wear morphology of the tool corresponding to unhydrogenated alloys was massive spalling, but the main wear morphology of the tool corresponding to the titanium alloy with 0.29% hydrogen content was punctate spalling.