橡胶模制品的盒式压模

<正> 面积接近平板硫化机热板面积(400×400,600×600,800×800毫米~2)的多腔压模具有相当大的外形和重量,需要在重型机床上加工。大量制造尺寸不大的橡胶制品(油封、密封圈等),往往采用过种大尺寸的压模。而这类制品的制造精度和光洁度都较高,因此对制造该类制品的多腔模具也应具有较高的精度和光洁度。例如制造O形密封圈的多腔压模基本上有两种结构:一种是将型腔直接加工在上模板和下模板上,加工中应设     

SMC制品模压模具局部后打孔结构设计

基于纤维增强的树脂基复合材料模压成型工艺的特点,针对模压制品上安装孔要求强度高、飞边小、内壁光滑的特点,设计了一种模压模具合模后局部挤压成型孔的结构,不仅增强了孔周围的强度,而且减少制品孔周围的飞边,可避免后续制品孔位在成型后进行修边导致孔的位置精度下降的问题,提高了制品质量。     

括弧楔锁模十字轴径向挤压模具设计

十字轴因形状所致,其挤压成形无法采用传统的上模插入下模的闭式锻模结构。给出了括弧楔锁模十字轴无飞边径向挤压新型模具结构。该模具采用上凹模与浮动的下凹模对合结构,锻件在2个凹模和凸模形成的封闭模腔中挤压成形,生产的锻件无飞边,锻件精度和机械性能显著提高。结果表明,可降低生产成本,提高产品质量和生产效率。     

新型螺旋伞齿轮坯锻模设计

螺旋伞齿轮坯原锻模生产的锻件内孔有纵向飞边,难以去除,妨碍后续加工。给出实用的新型锻模结构。该锻模采用浮动模芯和浮动凹模结构,锻件在两个凹模形成的的封闭环形模腔中成形。生产的锻件无飞边,料块质量减轻5.5%,显著降低了生产成本。     

新型螺旋伞齿轮坯锻模设计

螺旋伞齿轮坯原锻模生产的锻件内孔有纵向飞边，难以去除，妨碍后续加工。给出实用的新型锻模结构。该锻模采用浮动模芯和浮动凹模结构，锻件在两个凹模形成的的封闭环形模腔中成形。生产的锻件无飞边，料块质量减轻5．5％。显著降低了生产成本。     

冷挤压模具结构的改进

针对某精密零件加工成形中存在的难点,分析了目前所使用的冷挤压模具结构中存在的飞边大、模具寿命低等问题,提出了模具结构改进措施.改进后的模具将凹模的结构形式由原来的整体式改变为分体式结构,即定位部分与凹模部分分开.改进后的模具解决了凹模内两侧及底部表面粗糙度不易加工以及分体结构带来的飞边问题,提高了模具寿命.通过试模证明,该模具生产出的零件表面质量好,精度满足要求,模具寿命也由原来的12件增至现在的100件.     

无飞边多腔橡胶密封圈压模的设计制造

介绍了一种无飞边、多腔、圆截面橡胶密封圈压模的设计方法及制造技术,采用这种方法设计制造的模具结构简单、可靠 ,生产的产品质量良好。     

滑动叉无飞边锻造工艺研究

滑动叉传统上采用开式模锻工艺生产,飞边大,材料浪费严重而且尺寸精度差。为了降低锻件成本,针对滑动叉的形状特征,提出一种无飞边模锻的新工艺,使预制毛坯在封闭的模腔内成形,实现净成形或近净成形。应用Deform 3D模拟研究了滑动叉无飞边锻造工艺过程,模拟验证结果表明,新工艺显著地提高了材料利用率和成形质量,降低了锻造载荷。     

新型圆柱齿轮精锻模

提出了圆柱齿轮新型精锻模和挤压模结构 ,论述了齿轮精锻模齿形设计和加工方法。用新型精锻模在摩擦压力机上一次锻击 ,使圆柱齿轮完全成型 ,锻件无飞边。齿轮锻件经过退火和表面清理 ,用新型挤压模在液压机上挤压精整 ,显著提高了精锻齿轮精度和精锻模寿命     

数控加工假肢接受腔阳模刀位点算法的研究

对加工假肢接受腔阳模刀位点的不同算法进行研究,并进行了试验验证,最后找出满足加工精度要求的刀位点算法,提高了接受腔阳模的加工质量。     

Andreev reflections in a Bi<Subscript>1.8</Subscript>Pb<Subscript>0.3</Subscript>Sr<Subscript>1.9</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>x</Subscript> break junction

The current-voltage characteristic (CVC) of a break junction made from polycrystalline Bi_1.8Pb_0.3Sr_1.9Ca₂Cu₃O_x is investigated. The experimental CVC has a hysteretic feature that reflects part of the curve with a negative differential resistance. The CVC is discussed within the framework of the Kümmel-Gunsenheimer-Nicolsky theory that takes into account multiple Andreev reflections in superconductor/normalmetal/superconductor junctions.     

Magnetoelectrical effect in layered composites PbZr<Subscript>0.53</Subscript>Ti<Subscript>0.47</Subscript>O<Subscript>3</Subscript>-Mn<Subscript>0.4</Subscript>Zn<Subscript>0.6</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript>

The magnetoelectric (ME) effect in two- and three-layered composites made up of polarized ceramic plates of lead zirconate-titanate PbZr_0.53Ti_0.47O₃ (PZT) and manganese-zinc ferrite Mn_0.4Zn_0.6Fe₂O₄ (MZF) has been studied. Dependences of the transverse ME voltage coefficient (α₃₁) on the magnetostrictive layer thickness and the magnetic field intensity and frequency have been established. The mechanical coupling coefficient of the composite plates has been estimated. Results obtained for two-layered PZT-MZF structures have been analyzed using the method of efficient medium parameters.     

Electronic structures of Heusler alloy Co2FeAl1-xSix surface

We have calculated the electronic structures of Co2FeAl1-xSix(101) surface using first-principles method based on the density functional theory. Because of the surface effect, the minority spin band gap at the Fermi level disappears at the surface of bulk Co2FeAl1-xSix. However, beneath the surface, the minority spin gap opens at the Fermi level, which indicates that the electronic structures of Co2FeAl1-xSix(101) be-come close to that of bulk phase. Accordingly, the Co2FeAl1-xSix(101) surface is a composite tri-layer structure that corresponds to the weakening of half-metallic property in Co2FeAl1-xSix films. Even though, the spin polarization of Co2FeAl1-xSix(101) surface is still larger than that of Co2FeAl or Co2FeSi materials, making Co2FeAl1-xSix a promising spintronics material.     

Connectionism;Backpropagation;Structure;Interpretation;Symbolic Logic

A particular backpropagation network, called a network of value units, was trained to detect problem type and validity of a set of logic problems. This network differs from standard networks in using a Gaussian activation function. After training was successfully completed, jittered density plots were computed for each hidden unit, and used to represent the distribution of activations produced in each hidden unit by the entire training set. The density plots revealed a marked banding. Further analysis revealed that almost all of these bands could be assigned featural interpretations, and played an important role in explaining how the network classified input patterns. These results are discussed in the context of other techniques for analyzing network structure, and in the context of other parallel distributed processing architectures.     

Thermodynamic Assessment of PrCl<Subscript>3</Subscript>-CaCl<Subscript>2</Subscript> and NdCl<Subscript>3</Subscript>-CaCl<Subscript>2</Subscript> Systems

By using the CALPHAD technique, an assessment of the binary PrCl₃-CaCl₂ and NdCl₃-CaCl₂ systems have been carried out. From measured phase equilibrium data and experimental integral properties, the PrCl₃-CaCl₂ and NdCl₃-CaCl₂ phase diagrams were optimized and calculated. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated results by present method agree well with the experimental data.     

Connectionism;Neural Networks;Learning;Ambiguities;Reading

After a brief review of the different types and causes of ambiguous training data and the problems of learning from such data, a class of multi-target models are presented which suggest that neural networks are even better at solving these problems than previously realized. They are able to learn which non-ambiguous subset of a larger ambiguous set of training data best captures any underlying regularities in that data and hence optimize generalization while minimizing the problems of overtraining. It is also shown how the deliberate generation of ambiguous training data can begin to solve some of the longstanding representational problems of mapping time sequences, such as the alignment problem for reading and spelling. The general ideas are illustrated throughout with the well-known problem of tex-to-phoneme conversion, and detailed results of a range of neural network simulations are presented.     

Up-Date of a Thermodynamic Database of the ZrO<Subscript>2</Subscript>-Gd<Subscript>2</Subscript>O<Subscript>3</Subscript>-Y<Subscript>2</Subscript>O<Subscript>3</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> System for TBC Applications

The thermodynamic database of the ZrO₂-Gd₂O₃-Y₂O₃-Al₂O₃ system is up-dated taking into account new data on lattice stabilities of ZrO₂, Gd₂O₃ and Y₂O₃ and heat capacity measurements for the monoclinic phase Gd₄Al₂O₉ and phase with garnet structure Gd₃Al₅O₁₂. New data for the heat capacities of Gd₂Zr₂O₇ (pyrochlore) and GdAlO₃ (perovskite) as well as on the enthalpy of formation of fluorite solid solutions (Zr_1−x Gd _x )O_2−x/2 were found to be in good agreement with calculated results. In comparison with the previous assessment, taking into account new experimental data resulted in a change of the melting character of the Gd₄Al₂O₉ phase from a peritectic one to a congruent one in the Gd₂O₃-Al₂O₃ system. Correspondently, in the ternary system ZrO₂-Gd₂O₃-Al₂O₃, the melting character of the three-phase assemblage Gd₂O₃ (B), Gd₄Al₂O₉ and GdAlO₃ changed from eutectic to transition type U. The T ₀-lines for T/M and F/T diffusionless transformations and driving force of partitioning to equilibrium assemblage T + F were calculated in the ZrO₂-Gd₂O₃-Y₂O₃ system.     

Electrochemical corrosion behaviors of amorphous Co<Subscript>69</Subscript>Fe<Subscript>4.5</Subscript>Ni<Subscript>1.5</Subscript>Si<Subscript>10</Subscript>B<Subscript>15</Subscript> alloy

The corrosion behavior of an amorphous Co₆₉Fe_4.5Ni_1.5Si₁₀B₁₅ alloy ribbon was examined as a function of solution temperature (15 °C to 55 °C) and pH (3 to 11). The results of potentiodynamic polarization tests in H2SO4 solution, NaCl solution, and HCl + NaOH solution at various levels of pH showed that the corrosion resistance for the alloy ribbon significantly deteriorated with increasing temperature and decreasing pH for given conditions. The Co₆₉Fe_4.5Ni_1.5Si₁₀B₁₅ alloy was actively dissolved in solutions at pH 3 to 9 but passivated in a solution at pH 11. By comparison of the corrosion behaviors of Co₆₉Fe_4.5(Nb,Cr,Ni)_1.5Si₁₀B₁₅ alloys in the solution at pH 11, Ni was considered to contribute less in improving the corrosion resistance of the alloy than did Cr and Nb.     

Structure and properties of hydrogen-intercalated YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript>

The effect of hydrogenation at 150 and 200°С on the structure and magnetic susceptibility of YBa₂Cu₃O_y (123) with different hydrogen contents has been studied. Upon the incorporation of hydrogen, the phase transition of the 123 phase into a defect tetragonal 124 phase occurs. In contrast to the transition upon hydration, the phase transition upon hydrogenation takes place only for compounds characterized by high oxygen contents (y > 6.5). Depending on the compound structure and oxygen content, hydrogen atoms can both occupy interstitials in Cu–O planes to form HYBa₂Cu₃O₆ and join with oxygen to form an oxide–hydroxide. In contrast to hydration, upon hydrogenation of YBa₂Cu₃O_y, the substitution of europium for yttrium and alloying with cerium and zirconium oxides do not block the intercalation of hydrogen into the structure of the 123 compound.     

Structure and Inter-Diffusion Coefficients of Liquid Na<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>K<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> Alloys

Structure and atomic transport properties of liquid Na-K alloys are reported. Inter-diffusion coefficients of liquid Na _x K_1−x , alloys are calculated using scaling law proposed by Samanta et al. following Dzugutov which express the possible relationship between the excess entropy and diffusion coefficient. The interatomic interactions are described from the individual version of the electron-ion potential proposed by Fiolhais et al. The partial pair distribution functions and structure factors are calculated from the solution of Ornstein-Zernike integral equation with Rogers-Young closure. The evaluation with the composition of static structure and inter-diffusion properties are discussed.