Abstract: In the grinding process, conventional method of flood delivering coolant fluid by a nozzle in order to achieve chip flushing, cooling, lubrication and chemical protection of work surface. However the conventional flood supply system demands more resources for operation, maintenance, and disposal, and results in higher environmental and health problems. Therefore, there are critical needs to reduce the use of cutting fluid in grinding process, and MQCL grinding is a promising solution. MQCL grinding refers to the use of cutting fluids of only a minute amount typically of a flow rate of 10 to 100 ml/hour which is about hundreds orders of magnitude less than the amount commonly used in flood cooling condition. The evaluation of the performance of the MQCL technique in grinding consisted of analyzing the behavior of the tangential cutting force, G-ratio, Surface morphology and roughness. The results presented here are expected to lead to technological and ecological gains in the grinding process using MQCL.
Abstract: In this paper, an analytical model is developed for prediction of temperature rise on workpiece surface during machining and orthogonal cutting is studied. The shear heat source created in the primary zone and the friction heat source on the tool-workpiece interface determine the workpiece temperature. The proposed model is verified with FEM simulation and experimental measurements of temperature on AISI4340 in the literature. With the analytical model presented here, substantial reduction in computational time is achieved in the predictions of machining workpiece temperature rise.
Abstract: In the grinding process, conventional method of flood delivering coolant fluid by a nozzle in order to achieve high performance finishing. However, hydrodynamic fluid pressure can be generated ahead of the contact zone due to the wedge effect between wheel peripheral surface and work surface. In the paper, a theoretical hydrodynamic pressure modeling is presented for flow of coolant fluid through the grinding zone in flood delivery grinding. Moreover, coolant induced force can be calculated by integrate the hydrodynamic pressure distribution over the whole contact length. The theoretical results show that the hydrodynamic pressure was proportion to grinding wheel velocity, and inverse proportion to the minimum gap between wheel and work surface and the maximum pressure value was generated just in the minimum gap region in which higher fluid pressure gradient occuring. It can also be concluded the pressure distribution was uniform in the direction of width of wheel except at the edge of wheel because of the side-leakage. Furthermore, the hydrodynamic pressure and coolant induced force at wedge-like zone were also investigated experimentally. The experimental results show the theoretical model is agreement with experimental results and the model can well forecast hydrodynamic pressure distribution at contact zone between grinding wheel and workpiece.
Abstract: Surface machining system based on spherical coordinate is present for the large thin-walled director sphere part turning, to improve the efficiency and quality of part machining. In this system, a thickness surface B-spline model is set up based on spherical coordinates, the space spiral path generation method is planned, row spacing angle is determined by scallop height and blunt radius of cutting tool, and back cutting depth optimization treatment and space spiral interpolation algorithm are present.
Abstract: Titanium alloys are widely used in aerospace industry due to their excellent mechanical properties. Because of their low thermal conductivity, high chemical activity, large friction coefficient and so on, such problems occur during the cutting process as high cutting temperature, large specific cutting force and serious tool wear, leading to low machining efficiency. The cutting force, forms of tool wear; wear mechanics were experimentally studied and analyzed while machining titanium alloy TC4 using carbide tools YS8 and YG8. The experimental results indicated that the tool wear of YG8 influenced cutting force not very remarkable when flank wear smaller than 0.25mm. But when the flank wear was bigger than 0.25mm, the cutting force increased rapidly with the flank wear increased. And the tool wear influenced the cutting force dramatically. The forms of tool wear during machining TC4 using carbide tool were adhesion wear, tool chipping and. The desquamation and chipping of tool caused by adhesion wear were the main reason of the tool failure.
Abstract: Thin-walled structure is easy to vibrate in machining. The dynamic milling model of thin-walled workpiece is analyzed based on the analysis of degrees in two perpendicular directions of machine tool-workpiece system. In high speed milling of 2A12 aluminum alloy, the compensation method based on the modification of inertia effect is proposed and accurate cutting force coefficients are obtained. The machining system is divided into “spindle-cutter” and “workpiece-fixture” two sub-systems and the modal parameters of two sub-systems are acquired via modal analysis experiments. Finally, the stability lobes for high speed milling of 2A12 thin-walled workpiece are obtained by the use of these parameters. The results are verified against cutting tests.
Abstract: Surface roughness has a great influence on the performance of the mechanical parts and on the production costs. This paper discusses the possibility of enhancing the surface quality during face and straight turning by using a combined tool body material made of composite and steel compared with standard tool body material. The combined tool body material decreased the surface roughness of the machined part by 23% to 27%.
Abstract: The purpose of this investigation is to recognize the wear mechanisms of cemented carbide tools in dry hard turning of stainless steel (1Cr18Ni9Ti). From the view point of machining, stainless steels are often considered as poor machinability materials. Turning tests were carried out by using a CA6140 lathe and a cutting force measuring device. For this purpose, both microscopic and microstructural aspects of the tools were taken into consideration. Meanwhile, the cutting forces are also measured in the experiment. The chips were analyzed by scanning electron microscopy. The machinability of 1Cr18Ni9Ti austenitic stainless steels is examined in terms of tool life and cutting parameter presented in this paper. Results show that cutting forces vary greatly with the experimental cutting parameters. Analysis indicated that tool wear mechanisms observed in the machining tests involve abrasion wear, thermal and fatigue shock wear and adhesive wear.
Abstract: Performance of tool has always been a puzzle in the course of high manganese steel drilling. In this paper, improvement of drill tool is been done on drill bit structure and parameters of cutting tip by means of analyzing geometric parameter. By utilizing simulation method correctly, the influence of bit parameter on drilling force is analyzed. Meanwhile, by adopting the way of dividing into groups, comparison experiment between improved and no improved has been done. The comparison analysis of test results is carried out including tool life, wear and drilling force. The conclusion showed that the improved bit has better performance.
Abstract: The processing stability of machine tool system is studied in this work. In terms of the mass distribution and the need of sufficient energy to keep chatter, it is most possible that the chatter will occur on the final executive component of a machine tool. Based on it, the machine system may be simplified as a regenerative chatter model with double elastic bodies. This new model can adapt to improvement of component structure well. When there is a big difference between the receptances of two elastic bodies, the one with bigger receptance should become the active body of chatter, namely it is the weak one of the system. When the receptances of two elastic bodies are close, then the structure of two bodies should be optimized.