Key Engineering Materials Vols. 315-316

Abstract: High speed milling experiments using nitrogen-oil-mist as cutting medium were undertaken to investigate the characteristics of tool wear for Ti-6Al-4V Alloy, a kind of important and commonly used titanium alloy in the aerospace and automobile industries. Uncoated carbide tools have been applied in the experiments. The cutting speed was 300 m/min. The axial depth of cut and the radial depth of cut were kept constant at 5.0 mm and 1.0 mm, respectively. The feed per tooth was 0.1 mm/z. Optical and scanning electron microscopes have been utilized to determine the wear mechanisms of the cutting tools, and energy spectrum analysis has been carried out to measure the elements distribution at the worn areas. Meanwhile, comparisons were made to discuss the influence of different cutting media such as nitrogen-oil-mist and air-oil–mist upon the tool wear. The results of this investigation indicate that the tool life in nitrogen-oil-mist is significantly longer than that in air-oil-mist, and nitrogen-oil-mist is more suitable for high speed milling of Ti-6Al-4V alloy than air-oil-mist.

Abstract: In the paper, a new technology combining conventional CBN electroplating and thermal diffusion in vacuum to produce gear-honing-tool for hardened tooth is introduced. The two factors, such as planting CBN abrasives and combination between electroplating layer and matrix that can affect the quality of gear-honing-tool, are investigated. Experiments show that using suspension CBN abrasive electroplating combined with thermal diffusion in vacuum can ensure the quality of planting CBN abrasives of gear-honing-tool and obtain the semi-metallurgy binding layer between CBN abrasives and matrix that withstands the force of honing gears.

Abstract: This paper introduces a novel economical direct metal forming process, which combines of traditional plasma welding processes and layer manufacturing process to fabricate sound metal part. As high heat inputs during welding could affect parts surface quality, a CCD visual monitoring system was used to monitor the process. To avoid the interferer from plasma arc light, the spectrum of plasma arc was measured and analyzed, and a narrow band filter system was designed. The images of molten pool were analyzed, and a fuzzy-PID controller was used to control the molten pool size. Experimental results prove that using this system can improve parts surface quality.

Abstract: Based on the theory of kinematics for multi-body system, the relative motion constraint equation is deduced according to the structure layout and the error distribution of the ultra-precision lathe Nanoform200. By solving the constraint equation, the corrective NC code is derived that can compensate the geometric errors. The error compensation software is developed aimed at the ultra precision manufacturing of optics parts. The cutting experiments show that the method and model in this paper can improve the accuracy about 50% for the ultra-precision turning of optical parts.

Abstract: Laser peen forming of sheet metal is a new plastic forming technique based on laser shock waves, which derives from the combination of laser shock processing and conventional shot peening technique, it uses high-power pulsed laser replacing the tiny balls to peen the surface of sheet metal, when the laser induced peak pressure of shock waves exceeds the dynamic yield strength of the materials, the sheet metal yields, resulting in an inhomogeneous residual stresses distribution in depth. The sheet metal responds to this residual stress by elongating at the peened surface and effectively bending the overall shape. On the basis of analyzing the mechanism of laser peen forming, the line-track-peening experiments of 45 steel sheets with 2 mm thickness were carried out; a curved sheet metal with deep layer of residual compressive stress was obtained. The preliminary experiment result shows that laser peen forming can offer desirable characteristics in shaped metals and is a valuable technique for producing components for a range of industries.

Abstract: In ultra-precision turning process, the predictive modeling of surface roughness and the optimization of cutting conditions are the key factors to improve the quality of products and raise the efficiency of equipments. In this paper, the application of genetic algorithm in identifying nonlinear surface roughness prediction model is discussed, and presents mixed genetic-simulated annealing algorithm approach to optimization of cutting conditions in ultra-precision turning. The experiment was carried out with diamond cutting tools, for machining single crystal aluminum optics covering a wide range of machining conditions. The results of fitting of prediction model and optimal cutting conditions using genetic algorithm (GA) are compared with least square method and traditional optimal method.

Abstract: In order to improve the robust performance for a type of nonlinear multivariable system, a new fuzzy variable structure control method is introduced in detail, which combined the features of traditional variable structure control method with the advantages of the fuzzy control theory. The present work realized the linearization of the nonlinear multivariable system, and then the new fuzzy variable structure control method is applied to control the linearization system. The robust experiments were carried out on the novel method. The results indicated that the required robust performance could be achieved with high efficiency by utilizing the new method.

Abstract: The purpose of this paper is to monitor the tool wear based on the image data of cutting tool in the face milling operation. The surface images of the different coated inserted blade cutters are captured using a machine vision system incorporating with the mutual information and image similarity analysis technique for processing the images. The milling test is designed by using Taguchi’s method. The experimental results indicate that the coating layer factor is recognized to make the most significant contribution to the over all performance. The TiAlN-surface multilayer coated inserted blade cutter has the least wear rate amongst these coated milling cutters and has the longest tool life in this experiment.

Abstract: Thermal shock resistance is one of the important properties for ceramic cutting tool materials in machining operation. Thermal shock resistance of a new SiC/Ti(C,N)/Al2O3 ceramic tool material is investigated in detail by means of the water quenching test. It indicates that the addition of Ti(C,N) and SiC is effective in the improvement of thermal shock resistance of the composite and the tested maximum temperature difference of thermal shock reaches about 330
. Microstructures of the ceramic samples after thermal shock have been observed and analyzed by SEM focusing mainly on the morphologies of cracks and the peeling off of grains as well as the accompanied oxidation phenomenon at elevated temperatures.