Key Engineering Materials Vols. 315-316

Abstract: Reversible cutting method is a new research thesis proposed to shorten processing route, decrease tool number and handling time, increase machining efficiency. The aim of the presented work was to analysis the effects of reversible fine machining sequence on surface integrity in machined layer. Nonlinear hardening during reverse loading and the change of the Bauschinger effect factor with plastic strain were properly taken into account. In experiments, the residual stresses have been measured using the X-ray diffraction technique (at the surface of the workpiece and in depth). Moreover, micro-hardness and surface roughness of machined surface are presented. Experimental data for the range of cutting parameters tested showed that the reversible fine machining produce the tensile residual stresses at the surface, which are critical in the performance of the machined components. The experimental 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. Surface roughness of machined surface with reversible finishing is discussed. Research results indicted that it can be adopted such planning which rough machining during advance stroke and fine machining or semi-finishing during return stroke in machining process. In this way, it has such advantages that increase machining efficiency and machining accuracy, decrease bending deformation.

Abstract: Abrasive waterjet (AWJ) machining is a new non-conventional machining technology. Compared with other conventional and non-conventional machining technologies, AWJ offers the following advantages: no thermal distortion, small machining force, high machining versatility, etc. Therefore this technology is regarded as a high potential technology in the field of machining difficult-to-cut materials. In this paper, a comprehensive review of research situation about the cutting performance, the cutting mechanism and the measures to improve the cutting quality is given. The application of abrasive waterjet machining in turning, milling and drilling is reviewed finally.

Abstract: Due to large deformation, high pressure and high temperature, the tribological behavior between tool and workpiece in high speed cutting is markedly different from that between mechanical parts. High speed cutting tribology is a interdependent scientific discipline, in which kinematics and friction between tool and workpiece, tool wear and fracture, match of mechanical, physical and chemical properties of materials between tool and workpiece, as well as influences of cutting conditions and external environment (such as air, cutting fluids) on tribology and machined surface are investigated. The discipline of high speed cutting tribology is the science base for tool materials design and predicting the tool life, surface integrity and cutting accuracy for high speed cutting. In this paper, the concept of high speed cutting tribology and its research development and prospect are presented.

Abstract: Using Mo powder, B-Fe alloy powder and Fe powder as raw materials, with proper forming additives, the slurry was prepared. The green body was formed by spray method on both sides of 16Mn and Q235 steel substrate separately. Both side ternary boride based cermet cladding materials FC-V16Mn and FC-VCuQ235 were fabricated by liquid phase sintering technology. Both materials have high hardness, bending strength and good corrosion resistance.

Abstract: With the advantage of Case-Based Reasoning (CBR), selection method about matching of cutting tools with workpiece materials is presented through establishing the matching knowledge and rules in such respects as mechanical, physical and chemical properties of cutting and workpiece materials. Intelligent matching system of cutting tools with workpiece materials is developed based on CBR. This system has such advantages as higher matching speed and better accuracy, which offers a strong support tool for material selection between the cutter and workpiece.

Abstract: In order to improve the forming precision of the stretch bending process for T section aluminum extrusions and meet the fine forming requirement of the aerostat blank parts, the elongation controlled stretch bending process finite element model is proposed, which is based on the basic principle of the stretch bending forming with respect to A-7B CNC Section Stretch Wrap Forming Machine by analyzing various factors that influence the qualities of stretch bending parts, and the numerical simulation of the stretch bending process and spring back for T section aluminum extrusions is carried out. The results of simulation show that the pre-stretching elongation has a major effect on stretch bending parts and finite post-stretching elongation helps to improve the forming qualities of the parts. Comparing with the experimental results, the spring back of the finite element simulation shows good agreement with that of the experimental results.

Abstract: This paper introduces a new arc envelop truing method of metal-bonded diamond grinding. It utilizes the arc profile of rotary cone-shaped truer, namely electrode, to envelop wheel profile during Electro-Contact Discharge (ECD) truing. The aim is to realize precision truing of diamond grinding wheel profile for grinding of hard-brittle material. The arc envelope truing principle of wheel profile was analyzed by the use of 3D spatial geometry to identify lean angle of the truer. Then the arc envelop truing and grinding experiments were carried out to investigate truing precision and ground surface in comparison with straight truing and GC stick truing. It was confirmed that the arc envelope truing can obtain sub-micro truing precision of metal-bonded diamond grinding wheel at the depth of cut of micro degree. It may improve greatly form accuracy and ground surface.

Abstract: In this paper, based on some disciplinarians about the configuration design of Parallel Robot Mechanisms (PRM), the theory bases was established for parallel structural configuration design by developing different types of the partly degrees of freedom (DOF) parallel configuration designs. The new method to synthesize the partly DOF parallel mechanisms, called constraint accession, is provided to the classification of kinematical chains by use of screw theory. The active kinematical chains control the necessary DOF and the passive kinematical chains control the needless ones. In this paper, the relevant active and passive kinematical chains are put forward and the constraint chains are classified in detail. It is demonstrated by an example that new configurations can be obtained by assembling different kinematical limbs.

Abstract: This paper study on the problem of fuzzy multi-objective optimization, provides the method uses multi-objective fuzzy matter-element optimization to solve the problem of multi-objective programming which the parameter of the model is fuzzy, and provides the process of a fuzzy simulated based genetic algorithm to solve this problem. And a instance of multi-objective optimization of fuzzy reliability is given, verified the genetic algorithm based on fuzzy simulation of multi-objective matter-element is validity, and the virtue of the algorithm not only can solve the problem that the objective function is generalized function, but also can solve the problem that the objective function is normal function.

Abstract: Single-phase nanocrystalline diamond composite is very difficult to sinter because of a huge amount of oxygen-containing and nitrogen-containing functional groups adsorbed on the surface of nanocrystalline diamond going against the yielding of diamond-to-diamond bonding. In this paper, silicon film was deposited on nanocrystalline diamond by means of atomic layer deposition (ALD) using silane as precursor, which would promote the sintering of nanocrystalline diamond as the bond. The structure and the morphology of Si-deposited nanocrystalline diamond were thoroughly studied by X-ray diffraction (XRD), high-resolution electron microscopy (HREM) and Fourier transform infrared (FTIR) spectra. The results confirmed that silicon film grew uniformly on every primary particle and functional groups adsorbed on the surface of nanocrystalline diamond were removed by this method.