Papers by Author: Si Qin Pang

Abstract: Tool life tests of continuous cutting superalloy GH2132 were carried out by WC/Co cemented carbide cutting inserts of different grain size and cobalt content, and flank surface wear morphology of the cutting inserts were observed by ZEISS continuous zoom stereo microscope and microphotograph system. The results show that grain size and cobalt content strongly influence the cutting tool life and tool wear, grain refinement and proper cobalt content are help to improve the tool life and the wear resistance of WC/Co cemented carbide. The wear mechanisms of different grain size and cobalt content of ultrafine cemented carbide tools were adhesion and notch, among them, adhesive was the main wear mechanism at higher cutting speeds.

Abstract: Three-bending test has been performed on the standard specimen and welding specimen with defect of low-alloy and high-strength steel in order to simulate the failure process of structural parts under loading, and the AE activities (number of hits) and stress-strain curve were measured during the whole loading process. The law of acoustic emission signals at different deformation stages has been investigated and the relation between AE characteristic parameters and the different deformation stages has been established. The typical AE waveforms such as friction noise, plastic deformation, welding microcrack initiation and propagation are obtained, which are analyzed by using spectrum characteristics analytical method. The spectrum characteristic parameters such as average frequency, peak frequency and frequency centroid, energy percentage of frequency spectrum part I and III of the typical AE defect signals are extracted, the distributing range of which are initially set. Study shows these five parameters have a closely relation with the nature of the AE signals, and based on these characteristics parameters different AE sources can be preliminary identified correctly. The study can provide some guidance to the practical application of AE acoustic emission technology in the industrial field.

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: According to revised Cailikefu’s rolling shear force formula, motion path equation of spatial seven-bar path is built, and mechanical model, with such new structural features as asymmetric and negative offset, is thus successfully established for 2800 mm heavy shear of some Iron&Steel Company. Shear force and bar force of steel plate, before and after adoption of asymmetric and negative offset structure, are analyzed, as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. The discovery is that back-wall push force could be kept large enough at rolling start-up (i.e. the time that the maximum rolling shear produces), meanwhile, back-wall push force is the most approximate to side forces with adoption of 60mm~100mm offset. Theoretical results and on-site shear quality both indicate that new structural features such as asymmetric and negative offset plays an important role in ensuring pure rolling shear and keeping blade clearance constant, which provide an effective means to improve quality of steel plate.

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: 35CrMnSiA, is a kind of important engineering materials that used widely in modern manufacturing fields. The machinability of 35CrMnSiA Steel with hardness of HRc40±2 in high speed turning process was studied in this paper. It is concluded that, when high speed turning of this ultra-high strength alloy steel, the chief wear mode of ceramics is the crater on rake faces; the interaction of depth of cut and feed rate is one of statistic significant effects on cutting force; the interaction of cutting velocity of cut and feed rate is one of statistic significant effects on surface roughness Ra; besides, the empirical formula of average cutting temperature, cutting forces, surface roughness Ra, was established.

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.