Key Engineering Materials Vols. 315-316

Abstract: Traditional adaptive control technologies in machining process optimization are limited in applications because they depend much on sensors, controllers and other hardware. An off-line optimization method for end milling process with constant cutting power is presented. On taking advantage of virtual machining which simulates milling process, acquires cutting parameters and predicts cutting forces, method taking constant cutting power as an objective is discussed to optimize feed rates and cutting speeds. Based on optimal result, the feed rates and spindle revolutions in NC program are re-scheduled. Controlled milling experiments show that machining time is reduced and machining stability is improved by using the optimized NC program.

Abstract: How to improve the surface quality of large-scale silicon wafer in the ultra-precision grinding process, will always be the most important issue discussed by the silicon wafer manufacturer. In this paper, the advantage of ultrasonic grinding is being explored. These advantages included small macro grinding force, grinding stress, low grinding heat, which will reduce the surface damage. Combined with relatively abrasive, a large-scale silicon wafer can be processed. Through the study, an experimental system for ultrasonic grinding of large-scale silicon wafer is designed. The working parameter is optimized and the expected result is obtained, which searches a new way for the practical implementation.

Abstract: As we know, it is a useful method to prolong cupping mould lifecycle by employing diamond as cupping mould, especially to cupping mould of cupping horniness material. However, the machining of diamond cupping mould is always difficult. The paper intends to use the method of ultrasonic and electric spark combined to process diamond cupping mould. Based on the theory research and experiment, a satisfied result is attained. The experiment proves that the method is feasible, which decreases not only the chances of short-circuit in the process but also the energy consumption and improves machining efficiency significantly. These advantages are obvious.

Abstract: The current surface strengthening process of microalloyed unquenched and tempered steel components is usually induction or laser quenching treatment. Subsequent to heat treatment, these structural parts are subjected to grinding, during which impairment of hardened materials can be caused by thermo-mechanical influence of the grinding process. This paper studies a new method of surface heat treatment by making use of grinding heat and stress to create favorable microstructures and promote high wear and fatigue resistance. This work outlines the influence of grinding parameters on the superficial hardening effect of 48MnV microalloyed steel. It was found that the thickness and hardness of the treated surface layer could be up to 1.6mm and HV750 respectively. The beneficial microstructure of the layer was created by an enhanced martensite transformation. It is highly possible that the method can be used to incorporate grinding and surface hardening into a single grinding operation to develop a cost-effective production method.

Abstract: The chip-breaking groove of a blade is one of the main factors influencing chip control. In this paper, we report the use of a virtual reality technique to optimize the shape of the groove on a blade according to the status of chip formation and breakage. First, by using the software, World Tool Kid, the virtual cutting systems were developed to determine the linkages between the moving parts in the machine tool and display the virtual course of chip formation and breakage. And then, the virtual reality of optimizing the shape of the turning blade groove was carried out, that is, during calculation of loci in dimensional movement and solving mathematical model of the chip breakage, by inputting the groove’s parameters and cutting conditions of the blade, and simulating the track in dimensional movement of a chip and the restricting relations between the chip and each barrier, the intersecting coordinates in dimensional points of chips and the breaking manner could be solved. For improper chip-breaking manner, by modifying the model parameters, the blade groove was recalculated until the chips could be broken with ease. Based on the shapes of chips, the shape of the blades’ groove can be optimized to get optimal shape.

Abstract: Based on the experiment of high speed milling ball-end milling forces, the model of ball-end milling force is established for high speed machining complex surface by differential method, and research on the principle of high speed ball-end milling force. Results show that the parameters of cutting layer are subjected to varying curvature of complex surface, and place in the unstable state, cutting force decreases as the curvature and the inclination angle increase. By means of lessening cutting speed’s grads and adjusting the inclination angle and the path interval of cutter to the variety of curvature, cutting force and its fluctuation can be depressed availably; the process of high speed ball-end milling can be obviously improved.

Abstract: To improve the collaboration efficiency of the networked manufacturing coalition for automobile die enterprise, the networked manufacturing system framework is put forward. Then the information model, resource model and organization structure model are studied one of the other. The information model contains three layers lengthways and the product lifecycle is divided into 5 stages on landscape; for the resource model, the resource is classified and described, the relationship between resource entities is analyzed. The participants of each member enterprise are grouped according to the task relevance in organization structure model, and collaborative discussion center is constructed for the participants to communicate. On the basis, the workflow model is then discussed, the activity in business process is described with UML, then the UML activity diagram is transformed to Petri net graph, thus the workflow model can be diagnosed and analyzed.

Abstract: The grain size and its identity of abrasives are of high importance to obtain the damage-free and low roughness surfaces in traditional polishing processes. The undesirable scratches will appear on the surface of workpiece, if the grain size of abrasives is of high decentralization, or some abnormal larger grains or impurities are interfused in polishing process. And it is very difficult to polish curved surfaces. A new polishing technology, which is called as polishing with flotative abrasive balls, is put forward in this paper, in order to solve the problems mentioned above. Some primary experiments and theoretical analyses are carried out. It is found that the contact pressure between workpiece and abrasive grains may be easily controlled, as a result, the depth of cutting may also be easily controlled and it is not sensitive to the grain size of abrasives. The new technology may also be used in the polishing of curved surfaces.

Abstract: Ceramic tool materials, 3Y-TZP added by TiN particles, were fabricated through hot-pressing techniques. The effects of TiN on their low-temperature degradation at 220# in air were investigated. It is shown that TiN can improve the stability of t-ZrO2 and inhibit the transformation from tetragonal to monoclinic phase, and that the content of TiN affects the stability of tetragonal phase and the propagation of tetragonal-to-monoclinic transformation into the specimen interiors. It is suggested that the grain-boundary phase prevents the nucleation of transformation, and that the high elastic modulus of TiN can prevent the propagation of phase transformation by resisting the volume expansion of transformation. When the content of TiN is 20wt%, the ceramic material shows better low temperature degradation resistance.

Abstract: Green cutting has become focus of attention in ecological and environmental protection. Water vapor is cheap, pollution-free and eco-friendly. Therefore water vapor is a good and economical coolant and lubricant. Water vapor generator and vapor feeding system are developed to generate and feed water vapor. The lubricating method of water vapor is that the water vapor jet flow is directly jetted on the cutting zone and it cancels the fluid phase penetrating the capillaries in cutting zone. So it increases the time reserve of penetration and improves the property of penetration and lubricating effect. In order to find the influenced disciplinarians on lubricating effect with nozzle diameter, the parameters of water vapor jet flow and cooling distance (the distance between nozzle and cutting zone), experiments are carried out which hard alloy YT15 (P10 type in ISO) tool is used in cutting C45 steel. Experimental results show that the cutting force becomes lowered and chip thickness becomes thinned with the nozzle diameter decreasing. With the saturated vapor pressure increasing and the cooling distance shortening, the cutting force is lowed and the chip thickness is thinned too. Therefore the application of water vapor as coolant and lubricant can realize the green cutting in industry.