Advanced Materials Research Vol. 900

Abstract: In micro-EDM machining process, the debris of materials is difficult to be removed form the discharging gap. This problem leads the instability of discharge state, and reduces the efficiency of discharge machining. A new method of PZT incentive synchronous compression discharge channel micro-EDM is developed based on the inverse piezoelectric effect of PZT ceramics, driving by a spark discharge and PZT sync pulse power. The composition of the system is described and many experiments have been done and the effects of parameters on electrode wear ratio (EWR) have been analyzed in this paper. The results indicated that increasing the voltage and width of pulse can lower the rate of electrode wear, increase the efficiency of electric-machining, while increasing the frequency of discharge pulse can lead the increasing of EWR.

Abstract: In order to provide evidence for the adjust of grinding concentration, we have did the experimental study on the grinding concentration of Dahongshan copper, the tests indicate that the best grinding concentration of Dahongshan copper is 70%. Generally, the advantage range of fine grinding concentration is from 65% to 75%,so we choose the acceptable range of grinding concentration from 65% to 70% .

Abstract: A new method of processing optical aspheric parts by of bending and forming is presented, and the processing is line contact. The grinding principle is given of the bending and forming method. Based on the Preston equation, the grinding conditions is put forward to the bending and forming method. The function of the pressure and the relative velocity on the any point of at the processing surface are made. The material removal function is deduced about the bending and forming method. The experiments shows the grinding average error is 0.0272mm using solid abrasive on parabolic parts, and the maximum error is 1.0038μm using abrasive belt on hyperboloid parts.

Abstract: The deformation behavior and constitutive equation of Mg-4Al-3Ca-1.5Zn-1Nd-0.2Mn alloy were investigated using hot compression tests at the temperatures range of 200, 250, 300, and 350°C with the constant strain rates of 0.001, 0.01, 0.1 And1 s-1. The influence of strain was also incorporated in the constitutive equation by considering the effects of strain on material constants which are consist of A, α, β, n and activation energy Q. The predicted flow stress curves using the proposed constitutive equations well agree with the experimental results of the flow stress for experimental Alloy.

Abstract: Lapping the parabolic work-piece with the lapping tool in bending method is a new technology, which has some good characters such as low cost, scope broad, easy operation, and high precision. The lapping tool is formed by the means of bending and forming with solid abrasives on it in the experiment. The experiment shows that parabolic workpiece can be lapped using this method. The experimental result indicates that the work-piece face shape precision is high with the lapping tool, the maximal error is 0.0881mm and the minimal error is-0.0011mm, and lapping efficiency is high and the cost is low.

Abstract: In this paper, the moulding conditions of urea-formaldehyde resin were optimized to prepare moulding plastic with good mechanical properties using orthogonal experimental design method. The effects of moulding temperature, pressure and pressing time on the impact strength and blending strength of urea-formaldehyde resin were studied and analyzed. The results showed that moulding temperature had most noticeable influence on the impact strength and blending strength of urea-formaldehyde moulding compounds. The ratio F of moulding temperature to the impact strength was 2.077; the ratio F of moulding temperature to blending strength was 1.082. The most optimum conditions of preparing samples for testing the impact strength were that moulding temperature was 155 °C, pressure was 30 MPa and pressing time was 12 min; and the optimum moulding temperature of preparing samples with high blending strength was 155 °C, pressure was 25 MPa and pressing time was 5 min.

Abstract: SiC material removal mechanism and ELID grinding mechanism is analyzed, the character and condition of brittle to ductile transition of SiC single crystal, the critical depth of cut, and surface formation mechanism of ductile mode grinding of SiC single crystal are studied, the experiment results show that ELID grinding can realize ductile grinding ,this will lower the surface damage and improve the machining efficiency.

Abstract: This paper mainly discussed the problems that the serious tool wear,the short tool life of difficult-to-machine nickel base superalloys GH4169,the experiment was processed to obtain the tool wear morphology of GH4169 with a new developed PVD-TiAlN coated carbide tool.The morphology of tool wear was observed by scanning electron microscopy (SEM),and element distribution of tool surface was analyzed by energy spectrum analyzer (EDS),And then through the above two aspects,analyses the main tool wear mechanism.The results show that the mainly wear patterns of coated tool are micro-chipping, micro-cracks and flaking in high speed milling GH4169 with TiAlN coated tool.The tool wear mechanisms are mainly abrasive wear, adhesive wear, diffusion wear and oxidation wear.

Abstract: At present, there is large-scale trend for chemical containers and reaction tower in the industry. In the large-scale equipment, U-shaped weld structure are widely used for splice weld of container wall. In this paper, by ABAQUS software, using plane models, U-shaped seam welding process was simulated which was commonly used in pressure vessels and tower equipment. For welding material part, the calculation use of "dead-actived elements" technique, and the weld material part was divided into finer grid. The calculation model of the plane model was created using CATIA software, the software plug-in software was used to transform the model to directly read the ABAQUS software model. Calculation can be given to each welding temperature distribution and stress distribution. At the same time, the welding process to consider the cooling after welding. Computer simulation gave the overall structure of the stress distribution and strain energy curve.

Abstract: Speckle pattern interferometry can be used to measure he displacement, strain and vibration, surface deformation and surface roughness. And dynamic laser speckle measurement with high accuracy has been widely used in measurement of surface deformation. Tool breakage is the main bottleneck of high-speed intermittent cutting development, therefore, obtaining stress distribution of milling tools is a base of improving the tool design and tool life. Using a speckle measurement method of double pulsed digital based on FPGA, which involves the laser cutter, tools and CCD, transforms the high-speed dynamic measurement to quasi-static measurement. As a result, we can get two speckle images of front and back milling cutter surface and calculate the deformation ,strain and stress distribution of the tool surface with analysis.