Advanced Materials Research Vols. 69-70

Abstract: The deflection of cutting wire on multi-wire saw is determined by cutting wire tension, diameter ingot feed force and some other factors, and it affects the quality of silicon wafers greatly. In this paper, the initial stage of cutting process is analyzed and modeled with three ODEs. Then the numerical solutions are solved by finding out the BVPs of each ODE. The numerical solutions showed the relationship between the deflection and the cutting parameters such as cutting wire tension, diameter and ingot feed force. This method is helpful for the further research of modeling the entire cutting process.

Abstract: A novel control strategy for on-line polishing wheel wearing compensation in a polyhedral glass grinding machine is proposed, which is mainly consisted of hybrid feed-forward feed-backward control scheme and adaptive wearing prediction algorithm. It has advantage of eliminating the size excursion of polishing roller during long term operation, while the implementation of high accuracy diameter measurement is unnecessary. Hence it greatly reduces the demand for precise sensor and complicated calculation algorithm. Consequently, surface polishing quality and flexibility of the grinding machine was enhanced greatly. Theoretical analysis and experiment result obtained from a laboratory prototype shows good agreement, which indicates that the proposed control strategy has good performance in polishing wheel diameter compensation applications.

Abstract: Grinding processes are mainly technique employed widely as a finishing and difficult-to machine such as hardness and brittleness materials machining. However in grinding process, high grinding zone temperature may lead to thermal damage to the work surface, induces micro-cracks and tensile residual stresses at the ground surfaces, which deteriorate surface quality and integrality of the ground surface. The work presented in this paper aims at evaluating the grindability and surface integrity of the nickel base superalloy resulting from the application of cryogenic cooling. Grinding experiments were conducted under three different environments: dry, mineral oil and cryogenic cooling jet. The grindability results have shown that while the cryogenic cooling generates the lowest grinding temperature, no significant differences over the specific grinding force components were observed. As for the ground surface integrity, however, substantial improvements were realized. The novel process not only obviously enhances surface quality and integrality of grinding surface, but also enables retention of the wheel sharpness for a longer period and reduces pollution of grinding fluid to nature.

Abstract: Based on the comprehensive summary of latest research achievements of Laser and EDM technologies in home and abroad, the other advanced machining technologies is summarized briefly, such as Ultrasonic Wave, Microwave machining techniques and their composite machining technologies, as well as High-speed (Super High-speed) Grinding, ELID Grinding and Interface Thermal Chemistry Reaction Aided Machining technologies developed on the basis of traditional grinding technology. At last, it is forecasted that the necessary direction of advanced technologies used for ceramics is combinatorial machining technologies of two or more kinds of advanced technologies.

Abstract: This paper presents a study of the Taguchi design methodology, which is applied to optimize flank milling operation parameters when machining titanium alloy Ti-6Al-4V in conventional and high speed regimes. This study includes cutting speed, feed rate and depth of cut. Experimental runs are conducted using an orthogonal array of L9(33), with measurement of surface roughness. ANOVA analyses are carried out to analyze the effect of these operation parameters, and the optimal parameters combination is determined by seeking the best surface roughness. The analysis of result shows that the optimal combination for good surface roughness is high cutting speed, low feed rate. Finally, confirmation run verifies the results, which indicated that Taguchi method is both efficient and effective in determining the Ti-6Al-4V flank milling parameters for the optimization with minimum number of trials.

Abstract: The traditional CNC system is established on conventional machine tool mainly using ball screws. This could not suitable for micro mechanical machining with linear motor which could provide high speed, high precision, fast response and zero backlash. In this paper, a 3-axis micro milling machine tool with an open CNC system has been developed based on motion controller and linear motors. Considering the requirements of micro milling several special functions just like micro cutting tool setting are provided in exploited control software. The system dynamic characteristics are evaluated through experiments with servo parameters adjustments. In the following machining experiments, the whole system is proved economically and effectively.

Abstract: Hardened steel is widely used for good mechanical property, but its machinability is bad comparatively. It is efficient to enhance metal removed rate when high speed milling (HSM) hardened steel, but tool wear is rapid. In this paper, high-speed milling experiments were carried out for hardened steel with TiAlN coated tools. The effects of milling parameters on tool wear and surface roughness were studied. The influences of different coolants, such as dry, MQL, cryogenic MQL conditions on HSM hardened steel, were compared with each other, results showed that cryogenic MQL HSM hardened steel had better effects that can better reduce tool wear, extend tool life.

Abstract: Based on the investigation of two traditional vibratory modes, this paper puts forward a novel vibratory mode in high speed tapping. Vibratory tapping on stainless steel with all kinds of vibratory modes is carefully studied. Experimental results show that the new vibratory mode not only preserves the machining effect of the separable vibratory tapping, but also increases the life of tap. Therefore this study provides a new solution to increase the performance of high speed vibrat- ion tapping.

Abstract: The end surface angle of workpece is one of key factors that affect burr sizes and shapes. In this paper, the burr formation process of different end surface angle is simulated with elastic plastic nonlinear element method based on ABAQUS. The influence of end surface angle of workpiece on burr formation processes in high-speed machining 2024 Aluminum alloy is analyzed. The influence of end surface angle on burr sizes and shapes is studied based on equivalent shear strain and negative shear angle. The results have investigated the mechanisms of burr formation fundamentally, which is the basis of burr minimization.

Abstract: The heat generation during metal cutting processes affects accuracy of the machined surface and strongly influences cutting forces and tool wear. Material property of coated tools is one of the most important factors effecting heat conduction and temperature on the rake face of coated tools. To find the action of thermal properties of coated cutting tools on cutting temperature, the temperature distributions were obtained with temperature-dependent properties and temperature-independent properties of coated tools using numerical method. The results indicated that temperature-dependent properties should be considered when calculating cutting temperature. To simplify calculation, selecting the thermal conductivities at average temperature to substitute for temperature-dependent properties can reduce calculating error. The conclusion provides a methodology for analysis of cutting temperature of coated tools, design of cutting tools and analysis of thermal stress within coated tools in manufacturing industries.