拼焊法兰焊接变形和控制

拼焊法兰在焊接过程中产生焊接变形,焊接变形大小将直接影响法兰尺寸精度,本文介绍了法兰的制造和焊接工艺,分析了法兰变形产生的原因,并提出了控制法兰焊接变形的工艺措施。     

高真空电子器件金属零件化学研磨工艺

普通型不锈钢化学研磨液无法消除毛刺、保证零件精密公差尺寸和表面粗糙度，严重影响高真空电子器件金属零件的使用性能。确定了一套完整的54cmFS高真空电子器件金属零件化学研磨工艺。介绍了该工艺的工艺流程及工艺规范。讨论了化学研磨原理及金属哑光表面控制。测量了54cmFS高真空电子器件金属零件利用该工艺化学研磨后的表面粗糙度、孔直径、显微毛刺尺寸、平面度、孔部真圆度。结果表明，该工艺可以使零件表面达到哑光状态、保证精密公差尺寸、改善表面平整度、促进零件孔的真圆度，降低了生产成本，具有较高的推广价值。     

蒸笼窑

蒸笼窑是日本首创的大型瓷套焙烧设备。在蒸笼窑内釉接二次烧成高度4公尺以上的特大型瓷套,产品性能稳定,克服了有机粘接产品长期运行中的老化问题,在国际上享有极高的声誉。为发展我国500～750仟伏超高压输变电设备,生产自己的特大型瓷套,并为制造更高电压等级的产品进行技术储备,一机部于1976年9月向西安高压电瓷厂、西安电瓷研究所下达蒸笼窑中间试验任务:要求研究大型瓷套烧成设备—蒸笼窑。本文介绍了中试工作的一部分。     

高压法兰内开孔金属O形环密封性能及变形失效分析

针对某压力容器法兰内开孔金属O形环在高压工况下,因法兰结构设计不合理导致O形环过度变形而引起的密封失效问题,建立了三维周期非线性弹塑性模型,分析了法兰侧壁间隙和压缩率对O形环接触应力周向分布和环体变形的影响。试验测试了工作压力下的O形环在不同法兰侧壁间隙和压缩率时的泄漏率,分析了O形环的变形特征,探讨了O形环在高压大侧壁间隙下的变形失效原因。结果表明：建立的有限元模型能准确地模拟O形环的力学行为和变形,计算曲线与试验曲线吻合程度良好;O形环的接触应力对法兰侧壁间隙更敏感,减小法兰侧壁间隙和增加压缩率都能提高O形环密封的可靠性;O形环在高压工况下容易产生颈缩变形,造成接触应力在周向不连续导致泄漏,控制O形环的预紧间隙并发挥法兰侧壁的约束作用能够改善此类变形。研究结果可为高压内开孔金属O形环密封的法兰结构设计提供参考。     

石膏模型设计简易计算公式

注浆成型的陶瓷制品设计中,都要经过石膏模型设计,也就是根据成品设计的几何形状、尺寸和所用泥料的总收缩率(干燥收缩和烧成收缩的总和)进行适当放尺,制成石膏模型,然后再翻制注浆操作(成型)用的石膏模具。有的产品(例如坐式便器)坯体结构复杂,一份成品图往往要有十几个甚至更多的尺寸。由于坯体在干燥和烧成过程     

透平膨胀机主轴与叶轮三角形联接的设计原理和工艺方法

介绍了透平膨胀机主轴与叶轮三角形轴(孔)联接的设计原理和工艺方法,剖析了德国三角形轴(孔)专用磨床(即多面型磨床)的工作原理和德国DIN 32711标准,并运用于铲齿车床的改装实践,确立三角形轴与孔的形状、尺寸、公差与配合的设计规范和制造方法。     

基于ABAQUS软件的U形薄壳加肋结构热变形分析

U形薄壳加肋结构在航空航天领域应用广泛,然而由于产品截面热变形,需要用专用工装或分别测量进行定位制孔,工序烦琐,制造周期较长。以经典层合板理论为依据,借助ABAQUS软件建立U形薄壳加肋结构的有限元模型,对其截面尺寸进行计算和预测,并与实际产品对比,结果表明:在局部建模中考虑钢模具的计算条件下的预测数值与实际产品基本一致,而由于整体建模未考虑树脂在固化变形中的作用,其计算结果较实际截面尺寸偏小;ABAQUS软件可用于该结构铺层产品的热变形预测。     

浅谈中空轴的加工工艺过程

中空轴是管磨机中的关键件，在工作中它承受着整个磨体及研磨体的运动载荷，在交变应力的作用下连续运行。根据它的使用和受力状况决定了它必须要有较高的制造精度和合理工艺手段，否则将影响磨机的正常使用和运转。１．尺寸技术分析：（３０１１０管磨机）（１）中空轴材质应不低于JC４０１２中有关ZG２３０－４５０的规定，加工前退火消除内应力；（２）加工后轴颈和R１２０处不得有影响机械性能的铸造缺陷；（３）中空轴对形位公差的要求也较高：Φ１２００h８轴颈与法兰Φ２１９５f９外圆同轴度≤０．１Φ１２００h８轴颈外圆椭圆度≤…     

复合材料U形梁成型模具设计

以复合材料U形梁为研究对象,综合考虑模具材料与复合材料热膨胀系数的差异、模具的结构形式、回弹角补偿以及构件脱模等因素,采用CATIA三维软件对复合材料热压罐成型模具进行数字化设计。模具为框架式阳模结构,采用Q235钢焊接制造,对模具成型曲面进行补偿修正从而减小或消除热压罐成型过程中构件的变形,对两侧缘条各设置1°回弹补偿角以保证U形梁的尺寸精度和脱模要求。该模具结构合理,成本低,可加工性好,型面公差符合要求,具有良好的刚度和气密性。经工艺验证,采用该模具生产制造的复合材料构件型面公差符合要求,U形梁变形角度控制在技术要求范围以内,满足产品技术条件和后续装配要求。     

论工艺因素对氧化铝陶瓷零件形位公差尺寸的影响

本文尝试运用材料学过程理论对陶瓷制造过程进行了分析,进而总结分析了影响95%氧化铝陶瓷零件形位公差尺寸的工艺因素,讨论了陶瓷制造过程的能量分配问题和统筹兼顾问题。     

电场强化夹套间不同构造管对流传热研究

文中以空气为工质,对水平光管、横纹管、花瓣管在夹套间的强制对流传热进行了高压电场强化(EHD效应)实验研究,揭示了EHD在强化对流传热上的一些基本规律。实验结果表明,外加高压电场对强化对流传热有较好的综合效果,在Re=5000,电极电压为30 kV的实验条件下,花瓣管、横纹管和光管的最大强化率依次为2.76,1.75和1.36。根据光管的实验结果,对有、无电场作用下的压力波动进行了时间序列分析,得出了Lyapunov指数,并从动力学角度分析了EHD效应对强化传热的影响。     

THE TENSILE STRENGTH OF PORCELAIN1

A method of accurately determining the tensile strength of porcelain has been developed. The ratio of tensile to compression strength was found to be 5.9 for the special porcelain studied. Triaxial porcelains gave an average ratio of 7.66. The tensile strength tests show in general a little more variation than compression strength tests. The tensile strength is of more significance in judging the quality of porcelain than it has been commonly considered.     

含电气石热释电功能瓷膜对水pH值的影响

本文比较系统地研究了含电气石热释电功能瓷膜的制备;探讨了含电气石功能瓷膜与水作用过程中水的pH值变化规律及其作用机理.实验结果表明:电气石的粒径越小、容器中水越少,其对水体pH值影响越明显;随着初始水温度的升高效果有更明显的趋势;含电气石功能瓷膜烧结在750℃下保温2 h为最佳热处理方式,还原气氛中热处理比在大气气氛条件下对水pH值影响明显.     

海上丝绸之路的审美情趣--以景德镇青花瓷为例

景德镇的青花瓷大规模出口外销,青花瓷器型与纹饰的多样性正是与"海上丝绸之路"诸多沿线国家民族文化融合的结果,沿线国家的审美情趣一定程度上影响了景德镇外销青花瓷的样式与制瓷工艺。呈现在世人眼前的景德镇青花瓷的艺术特征正是海上丝绸之路上审美情趣的综合体现。本篇将以元明至清初时期的景德镇青花瓷外销为例进行探究。     

镁质强化瓷的研制

本工作以MgO-Al2O3-SiO2和K2O－Al2O3-SiO2三元系统相图为理论依据，较深入系统地研究了滑石等主要原料、工艺条件对提高瓷胎机械强度的影响，确定了工艺、性能理想的坯料和与之相匹配的高强度釉的配方组成。研制的镁质强化瓷产品规整，瓷质细腻，色调柔和，各项性能指标均达到当前国际上流行的同类产品水平。研究认为：胎体中较多的原顽火辉石和少量的堇青石弥散在较少的玻璃相中，及较多交织成网的针状莫来石和极少的气孔是镁质强化瓷强度高的主要原因。     

宋代瓷盒生产专业化初探

宋代是我国瓷业发展史上的一个繁荣时期,宋代瓷盒的产量比唐代增加很多。宋代瓷盒不仅产量多,而且景德镇窑有专门从事生产瓷盒的作坊,也就是宋代瓷盒的生产出现了专业化。本文从三个方面论述了宋代瓷盒生产专业化出现的原因。     

750kV交流系统用棒形支柱瓷绝缘子研究

在国家发展750 kV高电压输变电网络的情况下,作为配电设备的关键产品——棒形支柱瓷绝缘子的国产化,是电瓷行业面临的主要任务。根据输变电系统对棒形支柱瓷绝缘子的技术要求,笔者介绍了800 kV棒形支柱瓷绝缘子的设计、计算、制造、试验等试制情况。根据产品的使用特点,对瓷绝缘子配方进行了改进;同时,对800 kV棒形支柱瓷绝缘子的结构抗震稳定性进行了计算。试验结果表明,产品通过了所要求的定型试验。     

The bending stress distribution in bilayered and graded zirconia-based dental ceramics

The purpose of this study was to evaluate the biaxial flexural stresses in classic bilayered and in graded zirconia-feldspathic porcelain composites. A finite element method and an analytical model were used to simulate the piston-on-ring test and to predict the biaxial stress distributions across the thickness of the bilayer and graded zirconia-feldspathic porcelain discs. An axisymmetric model and a flexure formula of Hsueh et al. were used in the FEM and analytical analysis, respectively. Four porcelain thicknesses were tested in the bilayered discs. In graded discs, continuous and stepwise transitions from the bottom zirconia layer to the top porcelain layer were studied. The resulting stresses across the thickness, measured along the central axis of the disc, for the bilayered and graded discs were compared. In bilayered discs, the maximum tensile stress decreased while the stress mismatch (at the interface) increased with the porcelain layer thickness. The optimised balance between both variables is achieved for a porcelain thickness ratio in the range of 0.30–0.35. In graded discs, the highest tensile stresses were registered for porcelain rich interlayers (p=0.25) whereas the zirconia rich ones (p=8) yield the lowest tensile stresses. In addition, the maximum stresses in a graded structure can be tailored by altering compositional gradients. A decrease in maximum stresses with increasing values of p (a scaling exponent in the power law function) was observed. Our findings showed a good agreement between the analytical and simulated models, particularly in the tensile region of the disc. Graded zirconia-feldspathic porcelain composites exhibited a more favourable stress distribution relative to conventional bilayered systems. This fact can significantly impact the clinical performance of zirconia-feldspathic porcelain prostheses, namely reducing the fracture incidence of zirconia and the chipping and delamination of porcelain.     

Comparative microstructural study of celadon excavated from Housi’ ao kiln site in China (Late Tang and Five Dynasties): Mi-se porcelain and ordinary Yue celadon

Mi-se porcelain provided a step change in the history of Chinese porcelain making and influenced kiln production of later generations as well as the aesthetic orientation of society. This work compares the microstructure of ordinary Yue celadon and Mi-se porcelain. The Mi-se porcelain glaze was found to be simpler and more uniform than ordinary Yue celadon, with only some bubbles existing in the glaze. Compared with ordinary Yue celadon, the residual quartz and pores in the Mi-se porcelain body were smaller. Mi-se porcelain production is more standardized than ordinary Yue celadon. The presence of calcium phosphate in the glaze indicates that grass wood ash was used in the Yue kiln. Our research confirms that Mi-se porcelain was not the best porcelain as selected from the Yue kiln products, but it is a type of celadon that was specially fired using fine raw material processing and certain firing techniques.     

Optical characteristics of Japanese porcelain bodies prepared from high plastic clay

Abstract

The absorption and scattering coefficients of porcelain bodies were measured with the aim of improving the optical characteristics of Japanese porcelain prepared from plastic clay. The spectral absorption of the bodies was 0·02-0·07 mm^-1, similar to that of European hard porcelain. It was found that absorption could be lowered by increasing the content of alkali metal. Scattering coefficient, 10 mm^-1 at 380 nm and 3·0 mm^-1 at 780 nm, was much smaller than that of European bodies, which is typical for porcelain produced from Japanese plastic clay. Scattering coefficient varied with wavelength, behaviour which was considered to result mainly from the amount of mullite crystals present. On a reflectance-transmittance diagram, all the data for the Japanese porcelain bodies were on a single curved line, again demonstrating typical optical characteristics for Japanese porcelain bodies produced from plastic clay. Based on these results, a way of improving the whiteness and translucence of Japanese porcelain bodies is discussed.