Papers by Author: Qi Xun Yu

Abstract: This article establishes the multi-target optimization model of numerically-controlled milling parameter and illustrates the optimization design and system realization through modified Genetic Algorithm (GA). This system adopts double-breakpoint crossing and self-adaptive mutation and inverse operator through transgenic technology. It improves its local searching ability and calculation speed.

Abstract: Nickel-based superalloy is one kind of typical hard-processing materials, its cutting force is more complicated than other materials. Studies have shown that Response Surface Methodology model is more suitable than classical linear regression model, especially regression coefficients are more significantly. And the analysis of the linear effects , secondary effects and interactions effects can be more effective ,so as to achieve a good effect of cutting force prediction, to provide a reliable basis for a reasonable choice of processing parameters.

Abstract: This article illustrates the production method and mechanical & physical properties of polycrystal cubic boron nitride (PCBN) cutting tool material. As shown by the turning machining of hardened steel, cold-hardened cast iron and composite materials, PCBN cutting tool is superior in cutting performance to cemented carbide and ceramics cutting tools. In recent years, with great improvement in production process and overall mechanical properties of PCBN cutting tool material, it can effectively make rough machining of ferrous metal. This article contributes to the popularization and application of this cutting tool.

Abstract: In this paper, the development and mechanical, physical properties on cermet cutting tool material are described. By using the cermet insert NT7 developed in recent years and WC based carbide insert YT14, the tool wear, impact and cutting force tests to high strength steel 38CrNi3MoVA (hardened and tempered, HRC36~40) are processed respectively. The results of these tests demonstrate that NT7 cutting tools have better performance on some characteristics, such as wear resistance, tool life and cutting force. And its ability of impact resistance is similar to YT14. These researches will benefit to the poplarizaion and application of cermet cutting tool.

Abstract: This article discusses the problem about the method for the optimization of cutting parameters. A newly developed computational method which is different from the former was used for the optimization of cutting parameters. This method has its advantages of the controllability of the precision and higher speed when the precision requirement of the system is not very high. It can optimize cutting parameters toward the objectives of maximum production rate, minimum production cost and maximum profit rate.

Abstract: Carbide tools play key roles in present machine manufacture. The mechanical property and cutting performance of carbide tools are improved obviously when adding micro rare earth (RE) elements into carbide tools. By means of some apparatus, such as materials testing machine, Scanning Electron Microscope (SEM), dynamometer, microscope and electron probe microanalyser, the traditional and RE carbide tools, P30 (YT5 and YT5R), P20 (YT14 and YT14R), M10 (YW1 and YW1R), K30 (YG8 and YG8R), are studied and compared by doing a lot of experiments. These experiments show that the bending strength, fracture toughness and anti-impact capability of RE carbide tools are improved remarkably, and their hardness increased a little. Moreover, the cutting force, tool-chip friction coefficient and wear of RE carbide tools decreased in cutting. In addition, the effect and cutting principium of RE element to carbide tools are analyzed and discussed, which is beneficial to the research and application of RE carbide tools.

Abstract: Diamond film made by adopting the Chemical Vapor Deposition (CVD) technology is a promising superhard material. The mechanical and physical properties of CVD diamond is between natural diamond and hot press polycrystalline diamond. The cutting tools made by CVD diamond can machine many kinds of material, such as nonferrous metals, non metallic materials and composites. CVD diamond is classified as thin and thick films, and the thick film cutting tools are widely used. However, the superhard cutting tools cannot be applied to the cutting of iron family metal and molybdenum (Mo). In this paper, data and curves on machining test of CVD diamond cutting tools are listed and then analyzed.

Abstract: Reversible cutting method is a research thesis proposed to shorten processing route, decrease tool number and handling time, increase machining efficiency. There are three movement ways, i.e. reversible feed motion, reversible primary motion and reversible composite motion. Primary motion is done by workpiece, conventional or reversible feed motion is done by cutting tool in the way of reversible feed motion, e.g. turning. Cutting velocity is passed to cutting tool, clockwise or anti-clockwise cutting movement is done by cutting tool in the way of reversible primary motion, e.g. milling, shaping, drilling (spade drill), reaming. Primary and feed motions are all reversible in composite motion, e.g. turn-milling. Chip deformation and machined surface with reversible finishing is discussed. A mechanical analysis is carried out to the workpiece deformation of slender shaft turning in normal direction and reversible direction. The result has been verified by experiments. Experimental data for the range of cutting parameters tested showed that the reversible fine machining produce the compressive residual stresses at the surface, which are critical in the performance of the machined components. Experimental research indicted that the results of micro-hardness of reversible fine machining technique are smaller than that of general fine machining show that decreased plastic deformation of the surface layer and work-hardening. It can be adopted such planning which rough machining during advance stroke and fine machining during return stroke in machining process.

Abstract: The kinds and the properties of composite materials and superhard cutting-tool materials are introduced in this paper. By using five kinds of superhard cutting tools, such as polycrystal cubic boron nitride (PCBN), polycrystal diamond (PCD), thin film and thick film of chemical vapor deposition (CVD) diamond and carbon nitride (CxNy), two kinds of composite materials (fiber reinforced and particle reinforced) have been turned. Many experiment data have been gotten. It is shown that the superhard cutting tool is the best for machining composite materials. Moreover, surface finish and cutting force in composite material machining are discussed.