Key Engineering Materials Vols. 431-432

Abstract: PCBN cutting tools is in high speed, high temperature and high pressure environment when high speed precision hard cutting hardened steel. Shear extrusion and slip effect in high speed cutting, cutting tools wear mechanisms are different from common cutting, even cutting tools wear mechanisms in high speed is in research stage at present. In this paper, coated PCBN cutting tools wear mechanisms in high speed cutting(v＝200~600m/min) GCr15 (HRC62-64) is studied, it is helpful to obtain cutting tools structure design, cutting parameters and improve cutting tools use efficiency.

Abstract: Selecting an appropriate strategy is very important to the Green Manufacturing implementation. Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis is a commonly used tool for strategic management. Here SWOT analysis in combination with AHP is used to the selection of GM strategy. The strategic factors system of SWOT analysis for GM strategy is constructed by analyzing internal and external environments of the enterprise. Then AHP based SWOT analysis is introduced in detail. A case study demonstrates the application of AHP based SWOT analysis in GM strategy selection and shows its feasibility and validity.

Abstract: Cutting force collected by experiment is transformed by continue wavelet in order to overcome the disadvantage that signal processing analyzes single variable. The eigenvector which can reflect tool wear state is extracted from scale-energy matrix based on analysis, and BP neural network is established to predict tool wear. Trained network is used for prediction by unknown sample. Results show that this method can identify and diagnose accurately tool wear state.

Abstract: Ti6Al4V is a difficult to machine alloy with low cutting efficiency and server tool wear. A series of orthogonal milling tests with coated and uncoated carbide insert was carried out. The tool life predictive models based on orthogonal experiment were developed. Finally, the cutting parameters for both tools in Ti6Al4V dry milling were optimized based on tool life-efficiency contour analysis.

Abstract: In this paper, the micro-topography of the milled surface and chips are investigated, and the milling mechanisms of ceramics are analyzed. The results show that there are many deep and flat craters due to material fractures on the milled surface of Al2O3 ceramics and evidence of plastic flow is also observed around the craters. The milled surface of Si3N4 ceramics is smooth and even, and the trace of plastic flow can be observed. The abrasives after milling are very different from those before milling, which reflects the strong impact between abrasives and materials during the milling process. It is shown that the dominant milling mechanisms of ceramics are crack and exfoliating due to brittle fracture and plastic distortion according to the form of the chips.

Abstract: Based on reciprocating electroplated diamond wire saw (REDWS) slicing experiments, a study on REDWS machining brittle-ductile transition of single crystal silicon was introduced. The machined surfaces and chips were observed by using Scanning Electron Microscope (SEM), and some experimental evidences of the change of material removal mode had been obtained. The experimental results indicate there is a close relationship between material removal mode and the ratio r value of ingot feed speed and wire speed, through controlling and adjusting the r value, the material removal mode can be complete brittle, partial ductile and near-ductile removal.

Abstract: Grinding process can be considered as micro-cutting processes with the irregular abrasive grains on the surface of grinding wheel. The grain-workpiece interface directly forms the workpiece surface. Therefore, the study of the grain-workpiece interaction through micro-cutting analysis becomes necessary. But the experiments for single grain cutting are difficult to perform. Aimed at this problem, single grain cutting simulations of AISI D2 steel with a wide range of cutting parameters have been carried out with AdvantEdgeTM in this study. The effect of cutting parameters on cutting force, specific cutting force, material removal rate and critical depth of cut has been analyzed.

Abstract: A computational fluid dynamic (CFD) model for submersion jet has been developed to investigate the hydrodynamics in nanoparticle colloid jet machining with small diameter nozzle about 0.21mm. With this model, the fluid field characteristics and pressure distributions in the system are computed under the condition of vertical injection and aslant injection when jet pressure is 4MPa. The corresponding material removal experiments in nanoparticle colloid jet machining have been done to validate the rationality of the CFD model. And the simulated data are in good agreements with the experimental results.

Abstract: A method for machining huge workpiece is proposed using coordinate transformation theory. The mathematical model of positioning is derived with nonlinear least square method and solved by iterative algorithm which is given by tangent plane iterative method. Then, initially generated tool paths are modified and optimized. The experiment demonstrates that this method for machining ultra-large-scale workpiece is feasible and correct. The proposed automatic positioning algorithm and tool path optimization method can be used to machine huge workpiece to improve accuracy and reduce cost.

Abstract: Laser rapid forming is a kind of new developed technology combining laser surface modification and rapid prototyping technology. It provides a powerful tool for the manufacturing and repairing of metal components. Laser rapid forming repairing experiments of 45 and 2Cr12 steel have been carried out with 316L stainless steel powder. Microstructure and properties of the repaired components are analyzed and tested with optical microscopy (OM), scanning electron microscopy (SEM) and electronic tensile experimental machine etc. Repaired components of different materials have been metallurgically bonded with the deposited layers, with fine microstructure, better mechanical properties and free of defects.