智能型国标公差自动标注系统的研究

在智能机械CAD系统ObjectD环境下,采用面向对象编程技术,用AQL语言编程实现国标公差自动标注的程序．     

预制-再制

文章集中探讨了二战以后也就是所谓"战后"时期的建筑设计与建造。涉及的不仅是实践层面的问题,同时也有伦理层面的思考。因为正是这段时期,由于大量房屋毁于战争,要给成千上万的居民提供住房。同一时期,建造材料稀少而紧缺,于是一种新的现实主义应运而生,并且在施工体系上也有所创建:不再是此前乌托邦时期现代建筑的"封闭"体系,而是一种被认为是"开放的"施工方式。这一时期的建筑师们也认同建筑设计应该自我调节以适应有限的资源与手段,当然,他们也使用了一定的技术措施尤其是那些新的技术,但并非不分场合的滥用。项目的急迫性往往要求对工业化制品或者构件进行变更,使得要对"预制"的东西进行"再制"。这一时期,人们允许更大的容差,接受偶发因素,以积极的眼光来看待"不完美";建筑的物质性层面变得非常重要,而再现性则必须后退;使用的材料都是那些唾手可得的,有时是工业化材料(钢),有时是传统材料(砖);另一改变是将那些仅起服务作用的东西暴露在外而不再遮蔽。以"粗野"一词,来表达这种直接的、裸露的、混合的、讲求实际的建造方式。文章研究了埃利森和彼得·史密森、柯布西耶、詹姆士·斯特林、亚历杭德罗·德-拉·索塔、希哥德·勒沃伦兹等建筑师,最后还研究了弗兰克·盖里——虽然他的作品显然不属于这一时期,但可以这一背景为基础来加以解读,就像今天的诸多先锋建筑一样。     

飞行员手臂侧向抗拉耐力的研究

此项研究使用了特殊设计的拉力装置，机械模拟在应急弹射时作用在飞行员上肢的侧向气流吹袭力，测量了１１９名飞行员在拉中央环姿态下，右手臂对侧向拉力的耐受限度。使用拉力传感器记录了脱手时作用在手上和前臂的力。测量了飞行员手的握力、身高、体重、上肢长、上臂长、前臂长和手长等参数。实验结果表明，手的握力和在手上测量的脱手力，随着飞行员年龄的增加而减少。握力对作用在手上的侧向脱手力有影响。脱手力随着飞行员握力的增加而增加。飞行员手臂对侧向拉力的耐受限度的平均值是５７４Ｎ。此项结果为设计飞行员上肢的气流吹袭防护装置提供了科学的依据。     

羧甲基纤维素接枝AM／DMDAAC共聚物的溶液性质

采用自由基溶液聚合法制备了羧甲基纤维素与丙烯酰胺／二甲基二烯丙基氯化铵的两性接枝共聚物（ＣＡＤ）。探讨了ＣＡＤ的溶解性质、在水溶液和盐溶液中的流变性质以及在不同浓度ＮａＣｌ、ＫＣｌ、ＭｇＣｌ２、ＣａＣｌ２与钙镁钠混合盐溶液中的粘度性质。结果表明；ＣＡＤ具有较好的溶解性，其溶液属假塑性流体，有较强的抗盐能力，大分子链间正、负离子基团的缔合作用影响其溶液性能     

槽轮机构的误差分析

作者运用概率论和数理统计方法.分析了槽轮机构本身的加工精度与其分度误差的关系,推出了按分度误差值确定槽轮机构尺寸公差的计算公式.     

Using economic criteria to establish manufacturing tolerances

In this article, we propose an approximate, but easily applicable, method that uses economic criteria to determine where to establish manufacturing tolerances when 100% inspection is performed. The method considers the Taguchi loss function and the relation between cost and manufacturing tolerance. The method we propose moves away from the usual approach in that it deals explicitly with the dependence of manufacturing costs of the products sold with respect to the manufacturing tolerance .     

Robust optimal design using a second-order tolerance model

In this paper we present a general, quantitative method for developing designs that are robust to variation in design variables and parameters. Variation is defined in terms of tolerances which bracket the expected deviation of uncertain quantities about nominal values. We specifically address the case where input variations are assumed to be random variables that are normally distributed. The method incorporates a second-order tolerance model as part of a nonlinear optimization process. The second-order tolerance model makes it possible to estimate the skewness of function distributions, which are modeled with a three-parameter gamma distribution. We apply the method to determine robust designs for 11 test cases that span a variety of problems; robustness is verified with Monte Carlo simulation. The method enables a designer to understand and account for the effects of tolerances, making it possible to build robustness into an engineering design.     

Sculptured surface tolerance verification with design datums

Sculptured or free-form surfaces are widely used in many fields with extensive applications. Once such surfaces are manufactured, surface inspection compares the manufactured surfaces with the surface design specifications to verify conformance. Although significant research and development efforts have been devoted to the design and manufacturing of products consisting of partial or sole free-form surfaces, the inspection of these surfaces is still a difficult task. For many engineering applications, a free-form surface is assigned a profile tolerance with reference to design datums for assembly, functionality and other manufacturing requirements. The paper discusses developments of surface inspection techniques for profile tolerance of free-form surfaces. The concept of datum direction frame is proposed to find the transformation information that localizes measurement data to design model. The technique consists of two major steps: localization of measurement data to the design system, based on the datum reference information; and further localization based on the information from free-form surfaces. Testing examples were carried out to validate the developed techniques. The new method does not need corresponding points from the datums of the design model and measured surfaces. Therefore, it is simpler, yet more robust. It can also be used conveniently in manufacturing processes.     

基于三维环境的智能化尺寸公差标注系统的开发

基于三维CAD软件Solid Edge环境，采用二次开发技术和变量化技术，提出了三维环境尺寸公差的智能化标注方法，实现了国标公差的自动标注，并且当与工程图相对应的三维零部件或装配模型尺寸变化时，其标注的公差会自动进行相应的变化。