Key Engineering Materials Vol. 693

Abstract: Micro-textured technology which studies in the field of tribology shows that micro-textured surface can effectively improve the situation of friction between the friction interfaces. In this article, micro-textured surface technology has been applied to the cutting tools, in order to study the cutting mechanism of micro-textured carbide tools. The effect of cutting parameters on surface friction characteristics was studied when cutting 45 steel with YT15 cemented carbide tools. The results shown that all surface friction coefficient of the samples got the best value when the feed rate is 0.14mm/r; an appropriate increasing in feed rate can reduce the surface friction coefficient in the low-speed cutting. Throughout the course of the test, the average of the surface friction coefficient of the 4th and the 5th sample tools are better than other tools.

Abstract: Ti-Si-C films were prepared on cemented carbide by chemical vapor deposition. The reactive gas system was CH₄, (CH₃)₄Si, TiCl₄ and H₂. The film was analyzed and tested by SEM, AFM, EDS, XPS, microhardness tester, friction and wear tester. The results indicate that the film is continuous and dense. At higher substrate temperature, the hardness of the film will be higher. When the substrate temperature is 850°C, the adhesion of the film is highest with coefficient of friction only 0.14.

Abstract: A discretization method is used in pre-stretching simulation to separate an aluminum alloy thick plate into layers. When the equivalent plastic strain in each layer is defined according to the residual stresses during quenching, the yield strength model can be developed to estimate its yield strength. Again, the curve of elasticity modulus is fitted in the light of the experimental data, which can reveal how the elasticity modulus changes with plastic deformation. Finally, in consideration of the non-uniformity of yield strength and elasticity modulus, the pre-stretching of the quenched 7075 aluminum alloy thick plate is taken as an example to numerically simulate the value and distribution of residual stresses at the pre-stretching ratio of 1.8%, 2.2% and 2.5%, respectively. It is known from the simulated results that, by using the proposed method in this paper, the obtained results of the distribution and magnitude of the residual stresses are in good agreement with the experimental measurements.

Abstract: Jet Machining has significant advantages in processing precision, processing speed, environmental protection, and social benefits, etc. For years, it has been applied in the processing of a variety of materials processing successfully. This paper summarized research achievements on processing characteristics, flow field properties, particle distribution of many kinds of Jets (gas jet, water jet, supercritical carbon dioxide jet ) processing comprehensively and cutting performance for different materials (flexible material, brittle material, super hard materials). It will offer reference for further researching work and design of this novel method. In the meantime it will promote the application of jet processing in industrial production.

Abstract: A novel principle of cup wheel grinding of rotating concave quadric surface was proposed. The mathematical model of machining process was established to prove the feasibility of precision grinding of rotating concave paraboloid based on the introduced principle. The conditions of non-interference grinding of concave paraboloid were mathematically derived. The processing range and its influence factors were discussed. The trajectory equation of abrasive particle was concluded. Finally, the math expressions of numerical controlled parameters was put forward in the process of grinding of the concave paraboloid.

Abstract: In order to acquire high machining quality and minimum machining time, cutting forces are usually modeled to understand the milling process, simulate or predict cutting forces, and optimize the machining parameters. In this paper, side milling tests were conducted on superalloy Inconel 718 with a solid carbide end mill, and the cutting forces vs. cutting time were measured. The average cutting forces were extracted from the measured instantaneous cutting forces under different feed rates of experiments, and the components of the shear forces and edge forces were determined by using the linear regression of the experimental data. The cutting force coefficients, including shear force coefficients and edge force coefficients, were identified. In addition, the algorithms of the mathematical model were implemented in Matlab. The predicted cutting forces were in good agreement with the experimentally measured forces, and the validation of the cutting force model was demonstrated.

Abstract: An optimization method of end mill geometry parameters is presented for minimizing cutting energy. The helical end mill geometry is established at first. Then, the helical flutes are decomposed a set of infinitesimal oblique cutting edges. At every oblique cutting element, the differential cutting energy, which consists of differential shear energy and differential friction energy, is calculated using oblique cutting theory. By integrating the differential cutting energy along each cutting edge in the end mill, the cutting energy can be predicted during end milling. The effects on cutting energy of end mill geometry parameters are analyzed. Finally, the end mill geometry can be optimized in order to minimizing cutting energy.

Abstract: When milling corners in high speed, it will lead the mutation of cutting force that affects the processing quality and processing efficiency. In order to study the influence of milling parameters on milling force in the corner. Firstly, an orthogonal experimental of corner is designed to study the influence of various cutting parameters on cutting force. Axial cutting depth, radial depth, spindle speed and feed speed, as the major influence factors, impact on cutting force in corner milling. Then, a cutting force model of corner is established based on a method of orthogonal experiment linear regression. The significance test of regression equation and regression coefficient shows that cutting force model is accurate. The cutting force model is used to predict the cutting force, and then select the appropriate cutting parameters.

Abstract: For the sake of research on the hot stamping property of high strength steel, the stamping forming of USIBOR1500P is simulated by the nonlinear finite element software Dynaform and Ansys/ls-dyna. The initial data simulated on USIBOR1500P is obtained by the hot tensile test. The simulation results show that the martensite weight percentage and Vickers hardness are in inverse proportion to stamping speed and initial die temperature. Otherwise, they are increased when the heat conduction coefficient is rising. Thus they affect the final properties of machinery of U-shape part. The maximum stress appears in the die and punch radius, and the minimum stress appears in the flange and the bottom of the blank. The minimum temperature value appears in the flange and the maximum temperature value appears in the die and punch radius.

Abstract: Usually, bigger diameter milling tools were firstly applied in rough machining of NC Milling for improving efficiency and reducing cost before semi-finishing. In order to make the surface of parts more smooth and get accurate dimension parameters and proper shape, it is necessary to select appropriate tools to carry out the finishing of NC Milling. Moreover, higher precision dimension or shapes of parts can be achieve by the method of the semi-finishing, which it can be carried out after rough machining of high efficiency. Currently, the main methods of semi-finishing include semi-finishing of using IPW and semi-finishing of using reference tool.