关于大型平板硫化机设计中若干问题的探讨

本文从橡胶制品硫化的三大要素(压力、温度、时间)入手探讨大型平板硫化机设计中应该注意的几个问题,如主机框板的刚度影响压铅的厚度偏差;热板表面温差的自控调节系统装置;硫化PVC产品时如何缩短热板的冷却时间等等。此外,还提出了解决这些问题的一些可供参考的办法。     

大规模过程系统优化标准算例库的建立

为了测试大规模优化软件求解性能,在改造序列二次规划(SQP)算法并开发出大规模非线性优化软件的基础上,建立了大规模过程系统优化的标准算例库.算例库根据不同的分类标准分为不同的算例集.算例库中既有测试优化软件鲁棒性、迭代次数等性能的小规模算例,又有测试优化软件计算时间、内存使用量等性能的大规模算例.算例中还有一些具有流程应用背景的大规模优化实例,用于检验优化软件对实际问题的求解能力.大规模标准算例库的建立为开发高效大规模优化软件提供了有力支持,同时也可以为相关领域的研究者提供帮助.     

大型电除尘器的进展

刚产大型硫酸生产用电除尘器的总体结构为板卧式钢壳外保温结构,滚动式平面轴承为支撑构件。阳极均为薄钢板轧制的板状极板,框架式阴极已经取代了重锤挂线式阴极,框架上可安装不同的阴极线。承重绝缘件为95瓷绝缘套管,保温材料为复合硅酸盐毡,厚度仅需100mm。近年来的运行表明,国产大型电除尘器的设备结构和技术性能已达到国外先进水平,有些方面还优于原来进口的设备。大型电除尘器的设计制造和使用都积累了一定的经验,并且仍在不断改进和完善。     

大型90°弯头应力测试与爆破试验研究

通过对一大型90°弯头进行应力测试与爆破试验,得到了内压载荷下该厚壁弯头的外壁应力分布情况,确定了弯头的薄弱部位,并将试验结果与理论计算结果进行了比较。试验结果可为大型厚壁弯头的设计,制造及使用提供参考数据。     

基于保证大型数控机床装配精度的方法应用

装配精度最终决定数控机床本身的加工精度,对于小型数控机床而言,在装配过程进行相关检测,根据结果通过相应的改进和完善,就能比较容易地确保装配精度;而对于大型机床,受条件限制,在自检的基础上,必须借助精密仪器进行检测验证;对于关键点的精度要求,还要辅以专业软件进行分析,并对结果进行比较,择优选取,以确保设备的装配精度。     

面向大型工件现场测量的光笔式视觉测量系统

研制了一种面向大型工件现场测量的光笔式视觉测量系统,对其中的关键技术进行了深入研究。该系统主要由带有红外LED光点的光笔、1台CCD摄像机、靶点亮度控制器、一维标定尺以及安装有测量软件的计算机组成。在对LED点光源光强控制方式及成像系统工作原理进行分析的基础上,设计并实现了以多靶点亮度自适应控制技术和主动离焦模糊技术相结合的靶点光斑图像生成技术。该技术保证了在大跨度测量范围内均能获得高质量的靶点光斑图像,解决了对焦成像中摄像机视场范围与景深有限的问题;针对光笔标定问题,提出了一种简便易行的现场标定方法,此方法只需要若干个辅助靶点和2个以上间距已知的圆锥孔,就可以同时确定光笔上各靶点及光笔测头在光笔坐标系下的坐标。实验结果显示:该测量系统在2~10 m空间长度测量标准差不大于0.095 mm,能够满足中等精度的大型工件现场测量要求。     

Special features of the formation of the microstructure and chemical heterogeneity in welded joints in alloys of the Al–Zn–Mg–Cu system alloyed with scandium

Special features of the formation of the microstructure and the development of chemical heterogeneity in the weld metal and heat-affected zone (HAZ) in arc welding of a complex alloyed alloy of the Al–Zn–Mg–Cu system are discussed. It is shown that the effect of welding heating results in melting of the phase components of the alloy in the HAZ with the formation of structures of the eutectic origin in the form of long interlayers at the boundaries of recrystallized grains, causing brittleness of the metal. Alloying the alloy with scandium reduces the intensity of the processes of recrystallization and the extent of liquation at the grain boundaries and also localizes the melting of the grains without the formation of thick eutectic interlayers.     

大规模集成电路封装用联苯型环氧树脂的制备及其结构与性能

采用３,3′,5,5′-四甲基-4,4′-联苯二酚与环氧氯丙烷在18-冠-6-醚(CE18)为相转移催化剂作用下,利用两步加碱法合成了联苯型环氧树脂（TMBP）,在反应温度为80 ℃、反应时间为8 h、NaOH用量为0.2 mol时,产率达83 ％。用核磁共振、红外光谱、X射线衍射、热台偏光显微镜和DSC对所制备的产物进行了结构表征。结果表明,合成的产物为TMBP,具有良好的结晶性,熔点为107.8 ℃,在冷却过程中出现液晶态。TMBP熔融黏度极低（0.02 Paos,150 ℃）,用TMBP与酚醛环氧树脂（ECN）共混,可降低体系的黏度,从而提高硅微粉的填充量和大规模集成电路封装材料的流动性。     

Effect of microstructure inhomogeneity on mechanical properties of different zones in TA15 electron beam welded joints

The effects of microstructure inhomogeneity on the mechanical properties of different zones in TA15 electron beam welded joints were investigated using a micromechanics-based finite element method. Considering the indentation size effect, the mechanical properties for constituent phases of the base metal (BM) and heat affected zone (HAZ) were determined by the instrumented nano-indentation test. The macroscopic mechanical properties of BM and HAZ obtained from the tensile test agree well with the numerical results. The incompatible deformation between the constituent phases tends to localize along the softer primary phase α where failure usually initiates in form of localized plastic strain. Compared with the BM, the mechanical properties of constituent phases in the HAZ differ substantially, leading to more serious strain localization behavior.     

Local inhomogeneity of mechanical properties in stir zone of friction stir welded AA1050 aluminum alloy

The local inhomogeneity of the stir zone in friction stir welded face-centered cubic metal was investigated, which has multiple activated slip systems during plastic deformation, by selecting commercial AA1050 aluminum alloy as an ideal experimental material. The local inhomogeneity was evaluated by uniaxial tensile tests using small samples with a 1 mm gauge length. The corresponding microstructural parameters such as grain size, misorientation angle distribution, and micro-texture, were quantified by the backscattered electron diffraction technique. A comprehensive model was used to reveal the microstructure−mechanical property relationship. The experimental results showed that the uniaxial tensile property changes significantly across the weld. The maximum ultimate tensile strength (UTS) occurred in the center of the stir zone, which was 99.0 MPa. The weakest regions were located at the two sides of the stir zone. The largest difference value in UTS reached 14.9 MPa, accounting for 15% of the maximum UTS. The analysis on the structure−mechanical property relationship suggests that the micro-texture change with the location formed during the rotational material flow is the main reason for the local inhomogeneity.