基于UGII平台的注塑模具三维运动仿真

分析了典型注塑模具的结构及运动特点,介绍了注塑模具的运动仿真原理及其过程,最后基于UGII软件平台,以数码相机结构件模具为例,实现开模、脱模和合模的三维运动仿真,从而为注塑模具的设计提供了一定的可预见性,确保其结构的合理性。     

Unique microstructure and property of a 2024 aluminum alloy subjected to upsetting extrusion multiple processing

The microstructure and hardness of a 2024 aluminum alloy subjected to multi-pass upsetting extrusion at ambient temperature were studied. Experimental results indicated that with the number of upsetting extrusion passes increasing, the grains of the alloy are gradually refined and the hardness increases correspondingly. After ten passes of upsetting extrusion processing, the grain size decreases to less than 200 nm in diameter and the sample maintains its original shape, while the hardness is double owing to equal-axial ultrafine grains and work hardening effect caused by large plastic deformation.     

Hydriding-dehydriding properties of Mg2Ni alloy modified by ball-milling in tetrahydrofuran

A new approach of ball-milled Mg2Ni in tetrahydrofuran (THF) to improve the hydriding kinetics of Mg2Ni alloy is suggested and studied. It is found that the modified alloy displayed the improved activity for hydriding even at relatively low temperature (e.g., 323-373 K). In the case of the sample milled in THF for 20 h, the hydrogen content (mass fraction) reaches 1.6 % at 323 K, 2.1% at 348 K and 3.4% at 448 K, respectively. The use of THF during grinding led to the change of the structure, which is reflected by the broadening and weakening of the diffraction peaks in the XRD spectra. The XPS analysis shows that Mg (2s) binding energy peak of Mg2Ni after modification shifted from a lower binding energy to a higher one, indicating the charge transference between Mg and THF and the formation of catalytically active electron donor-acceptor (EDA) complexes on the surface of modified Mg2Ni alloy.     

Thermochemistry on coordination behavior of samaric chloride hydrate with diethylammonium diethyldithiocarbamate

The complex of samaric chloride lower hydrate-with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized conveniently in absolute alcohol and dry N2 atmosphere. The title complex was identified as Et2NH2[Sm(S2CNEt2)4] by chemical and elemental analyses, the bonding characteristics of which was characterized by IR.T he enthalpies of solution of samaric chloride hydrate and D-DDC in absolute alcohol at 298.15 K and the enthalpies change of liquid-phase reaction of formation for Et2NH2[Sm(S2CNEt2)4] at different temperatures were determined by microcalorimetry. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy, and the activation free energy), the rate constant, and three kinetic parameters (the apparent activation energy, the pre-exponential constant, and the reaction order) of liquid phase reaction of formation were obtained. The enthalpy change of the solid-phase title reaction at 298.15 K was calculated by a thermochemical cycle.     

Crystallization and microstructure evolution of amorphous Al85Y4Nd4Ni7 alloy

The mixture model of Al85Y4Nd4Ni7 alloy in which a partially crystallized amorphous alloy is regarded as a nanocomposite of an Al nanoparticle and a remaining amorphous matrix is presented. Its evolution in the process of crystallization has been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Mainly amorphous structure with α-Al nanocrystals embedded in the amorphous matrix has been revealed by melt spining the alloy. Crystallization is showed to occur in three stages: (I) crystallization of amorphous alloy and formation of A1NiY, A1NdNi and unknown crystalline phases, (2) formation of Al3Y and Al3Nd, and (3) formation of Al3Ni.     

Thermal expansion of lattice parameter of （powder） silicon up to 1473 K

The XRPD (X-ray powder diffxactometry) patterns of silicon powder with a unit cell structure of diamond were determined from 298 to 1473 K. Lattice parameters of Si linearly increase with temperature. The thermal shifts of the positions of all reflection peaks are linearly correlated with the temperature. The coefficients of the intrinsic linear thermal expansion and volumetric thermal expansion were determined as 3.87×10-6/K and 1.16×10-5/K respectively. It indicates that Si is still a suitable standard in the XRPD method at high temperatures.     

Closed-loop control of weld penetration in keyhole plasma arc welding

To improve the penetrating ability and the welding quality of keyhole plasma arc welding, a novel penetration closed-loop control system was established. In the system, welding current and plasma gas flow rate were selected as adjusting variables. The wavelet method was used to detect penetration status from welding arc voltage in real-time. The control strategy of one-keyhole-per-pulse was adapted to fulfill stable and high quality welding process. Experimental results show that the developed system can apparently increase the penetrating force of plasma arc and keyhole plasma arc welding is realized successfully in stainless steel with 10 mm in thickness. Moreover,the disturbances of gradual change and break change from 3mm to 6mm in thickness are come over due to the good response property of the developed system.     

Effects of pH value of reaction solution on structure and electrochemical performance of calcium-containing active material of secondary zinc electrodes

The calcium-containing active material of secondary alkaline zinc electrodes was prepared by a chemical coprecipitation method and characterized by scanning electron microscopy(SEM) and X-ray diffractometry(XRD).Their electrochemical performance was tested by the Galvanstatic charge-discharge method. The experimental results show that the sample synthesized at pH: 11. 15 has a typical calcium zincate crystal. The zinc electrode using this sample as active material shows higher discharge capacity, more negative discharge plateau potential and longer cycle lifetime.     

Operation optimization of concentrate burner in copper flash smelting furnace

The software that simulates the flow, temperature, concentration and the heat generation field in the Outkumpu flash smelting furnace, was developed by a numerical method of the particle-gas flow together with some chemical reaction models. Many typical operating conditions were chosen for simulation in order to obtain the effect of the distribution air, process air, central oxygen and the oil-burner position etc. The concepts about optimum op-eration, 3C(concentration of high temperature, high oxygen and laden concentrate particles), are concluded from these simulated results, which have been checked primarily by operational experiments.     

Three-dimensional combined finite-discrete element approach for simulation of single layer powder Compaction process

The application of a combined finite-discrete element modeling approach to simulate the three-dimensional microscopic compaction behavior of single-layer metal powder system was described. The process was treated as a static problem, with kinematical component being neglected. Due to ill condition, Cholesky‘s method failed to solve the system equations, while conjugate gradient method was tried and yielded good results. Deformation of the particles was examined and compared with the results of physical modeling experiments. In both cases, the inner particles were deformed from sphere to polygonal column, with the edges turning from arc to straight line. The edge number of a particle was equal to the number of particles surrounding it. And the experiments show that the ductile metal particles can be densified only by their plastic deformation without the occurrence of rearrangement phenomenon.