工艺尺寸链求解方法浅析

本文从工艺尺寸链的建立和封闭环、组成环、增、减环的查找和判别、计算公式的应用等方面介绍在机械制造工艺规程编制过程中工艺尺寸链求解的一种简便方法。     

基于VB的尺寸链计算程序的实现

介绍了利用VB程序设计语育实现平面线性尺寸链计算的应用程序的设计方法.该程序不仅具有良好的用户操作界面.而且其通用性较强.具有一定的实用价值.     

工艺尺寸链的建立及计算

制订零件加工工艺规程时需标注工序尺寸,确定工序尺寸有两种方法:一是定位基准与设计基准重合时,确定比较简单;二是当定位基准与设计基准不重合时,应按尺寸链原理来计算,尺寸链从几种不同的情况来进行分析计算.     

1FT5交流伺服电机装配尺寸链的分析和确立

建立了影响定、转子同轴度相关尺寸的装配尺寸链,通过装配尺寸链解法的对比分析,确定了伺服电机的装配法——大数互换法。通过实测数据对比验证了所采取的工艺措施是有效的。     

精密注塑件尺寸精度解决方案

1精密注射成型的概念精密注塑是指加工成型的注塑制品的尺寸重复精度很高,以致使用通用注塑机、常规的注塑成型工艺难以达到要求的一种注射成型方法。     

平面壁附近高分子链的尺寸和形状

The size and the shape of non-reversai random-walking polymer chains near an impenetrable, noninteracting fiat surface are investigated by means of Monte Carlo simulation on the simple cubic lattice. It was found that both size and shape are dependent on the normaLto-surface distance z0 of the first segment of chain. We find that the size and shape of chains, characterized by mean square radius of gyration (S^2) and mean asphericityparameter (A) respectively, show similax dependence on distance z0. Both (S2) and (A) reach the maximum at z0 = 0, then decrease with the increase of z0 and soon reach the minimum values, afterwards they go up continuously and approach to the limit values of free chain. The similar dependence of (S^2) and (A) on z0 can be explained by a positive correlation between A and S^2. However, the dependence of the correlation coefficient CA,S2 on z0 is very complicated and deserves further study. The overall density probability of segments is also investigated. Results show that segments near the surface are relatively less, and the symmetrical distribution disappears when the chain locates near the surface.     

减压阀尺寸的精确计算

减压阀尺寸的精确计算ＷｉｎｇＹ．Ｗｏｎｇ在众多化工过程的安全操作中，减压阀是一个重要的部件。一种较为大家熟知的计算减压阀适宜尺寸的方法是美国石油协会提供的ＡＰＩＲＰ５２０Ｉ法。对于汽液相混合物，ＡＰＩ标准假定：物流以均相混合物形式流过减压阀，并在出口...     

修理尺寸法在机修中的应用

介绍修理尺寸法其修理尺寸的确定及优缺点。     

注射成型橡胶制品尺寸精度影响因素

从成型零件的制造公差、型腔零件的磨损、制品的收缩率三个方面讨论了制品的公差形成的因素。     

直链烷基苯在造纸工业中的应用

本文介绍了直链烷基苯及其磺酸盐作为阴离子表面活性剂在造纸工业蒸煮制浆和废纸脱墨等过程中的应用。     

聚氨酯弹性体新型扩链剂的合成及应用

聚氨酯弹性体是一类综合性能优异的高分子合成材料,扩链剂对弹性体有重要的影响,能显著改善其性能.本文简单介绍了聚氨酯弹性体用新型扩链剂的分类,详细论述了一些新型扩链剂的合成和应用,并指出了聚氨酯弹性体扩链剂的发展方向和应用前景.     

建筑装饰材料尺寸偏差的计算机视觉检测系统

本文以墙地砖等建筑装饰材料为研究对象，以计算机视觉理论为基础，采用计算机图像处理技术，研究了墙地砖等建筑装饰材料尺寸偏差自动检测和识别的关键技术，并编制了该软件系统。     

精密注塑模型腔尺寸的设计计算

通过分析研究一些主要因素对精密塑件精度的影响,提出了精密注塑模设计和提高精密塑件精度的方法,并推导出精密注塑模的型腔尺寸设计计算公式。迷些对精密塑件的生产具有很好的指导作用。     

简化空穴理论状态方程在链状分子及有机溶剂液体中的应用

基于不完全晶体的热缺陷统计理论,将液体晶格中被占座席分率表示为对比温度的指数函数,推出了一个适用于聚合物,链状大分子及有机溶剂的液体状态方程。将此简化了的状态方程用于17种大分子链烃及10种常见的有机溶剂P-V-T计算,结果与实验值十分相符。与Simha和Somcynsky的空穴理论状态方程式相比较,计算大为简化且精度相当,易于应用至混合物体系。     

Chain statistics in polyethylene crystallization

The molecular mechanism of polyethylene crystallization in solution is revisited within the framework of the bundle model [Allegra G, Meille SV. Adv Polym Sci 2005;191:87]. Previous SANS/IANS results [Sadler DM, Keller A. Science 1979;203:263; Spells SJ, Sadler DM. Polymer 1984;25:739; Stamm M, Fischer EW, Dettenmaier M, Convert P. Faraday Disc Chem Soc 1979;68:263] from partially deuterated samples are used. It is proposed that the chain deposits on the growing lamella under the form of compact crystalline domains, their size being . The radius of gyration of the crystallized chain agrees with a model consisting of a linear sequence of crystalline domains connected by chain segments with random orientations. It is suggested that the whole chain is in a bundle meta-stable equilibrium and collapses in the vicinity of the growing lamellar edge, then crystallizing around secondary nuclei. Compactness of the crystalline domains is correlated to prior chain collapse in the liquid state. The observed proportionality to of the crystalline domain size is approximately explained.     

光扫描比浊法测定催化剂粒度分布

主要论述了光扫描比浊法测定催化剂粒度的影响参数,以及如何选择这些参数,找到最佳的参数条件使分析结果更准确、分析方法可行。     

Chain walking copolymerization of ethylene with cyclopentene - Effect of ring incorporation on polymer chain topology

Chain walking ethylene copolymerizations with cyclopentene (CPE) as the ring-forming comonomer were carried out in this study to investigate the tuning of polyethylene chain topology via the unique strategy of ring incorporation. Four sets of polymers containing five-membered rings on the polymer backbone at various low contents (in the range of 0-7.5 mol%) were synthesized by controlling CPE feed concentration at four different ethylene pressure/temperature combinations (1 atm/15 °C, 1 atm/25 °C, 1 atm/35 °C, and 6 atm/25 °C, respectively) using a Pd-diimine catalyst, [(ArNC(Me)-(Me)CNAr)Pd(CH₃)(NCMe)]⁺SbF₆⁻ (Ar = 2,6-(iPr)₂C₆H₃). The polymers were characterized extensively using ¹³C nuclear magnetic resonance (NMR) spectroscopy, triple-detection gel permeation chromatography (GPC), and rheometry to elucidate the chain microstructures and study the effect of ring incorporation on polymer chain topology. It was found that CPE was incorporated in the copolymers primarily in the form of isolated cis-1,3 ring units, along with a small fraction in the form of isolated cis-1,2 ring units. Significant linearization of polymer chain topology was achieved with ring incorporation in each of the three sets of polymers synthesized at 1 atm on the basis of the incrementally raised intrinsic viscosity curves in the Mark-Houwink plot and the significantly enhanced zero-shear viscosity of the polymer melts with the increase of ring content despite the decreasing polymer molecular weight. For the set of polymers synthesized at 6 atm/25 °C, the effect of ring incorporation on polymer chain topology was negligible or weaker due to their linear chain topology resulting at this polymerization condition. The results obtained in this study support the proposed blocking effect of backbone-incorporated rings on catalyst chain walking, and demonstrate that effective tuning of polyethylene chain topology from hyperbranched to linear can be conveniently achieved via CPE incorporation while without changing ethylene pressure or polymerization temperature.     

Size dependence of crystallization within spherical microdomain structures

We have investigated the size dependence of crystallization within spherical microdomains formed in various poly(ε-caprolactone)-block-polybutadiene diblock copolymers (PCL-b-PB). The crystallinity (χ) and melting temperature (T_m) of the PCL block are considerably lower than those of PCL homopolymer, and χ decreases steadily and T_m decreases only slightly with decreasing radius of PCL spheres (R) for a series of PCL-b-PB with a same molecular weight (M_n). When PCL-b-PB is compared with the similar R but different M_n, χ is significantly different, suggesting that the sphere size is not the unique factor to control crystallization within spherical microdomains.