精加工液压件阀孔中的金刚石铰刀的应用探究

为了能够使液压件阀孔加工度达到高精度,人们往往采用金刚石铰刀具,因其具有对孔件加工精度高、加工效率高,且加工的孔件表面光滑度高、使用寿命长的特点。文章通过对起重机用上车组合操纵阀阀门主孔的高精度加工的简单介绍,突出显示了金刚石铰刀所具有的技术特点以及液压零件高精度深孔加工中金刚石铰刀的运用。     

大深径比深孔加工工艺研究

在机械零部件的加工制造中,对于深孔的加工,一直是加工制造业中一项困难性高、操作复杂的任务。尤其在大深径比的深孔加工中,其加工工艺要求较高,技术性较强。本文以大深径比的喷嘴类零件深孔加工研究为例,对其加工工艺进行分析,对深孔加工的工艺设计方案进行较为细致的探讨。     

数控铣削机床孔加工工艺分析与精度控制

孔加工在零件加工中占有很重要的比重,孔加工质量的好坏往往影响着零件的使用性能,所以在生产中要特别留意影响加工质量的因素,并通过理论与实践结合的办法解决孔精度超差问题。文章介绍了数控加工孔的加工方法及其选择,钻孔、铰孔工艺的特点与加工要点,铣孔工艺,供相关人员参考。     

数控铣削机床孔加工工艺分析与精度控制

孔加工在零件加工中占有很重要的比重,孔加工质量的好坏往往影响着零件的使用性能,所以在生产中要特别留意影响加工质量的因素,并通过理论与实践结合的办法解决孔精度超差问题.文章介绍了数控加工孔的加工方法及其选择,钻孔、铰孔工艺的特点与加工要点,铣孔工艺,供相关人员参考.     

深孔螺纹加工方法的探讨

本文通过对结合深孔螺纹工件的结构特点和其加工工艺的特点分析,总结了进行深孔螺纹加工的有效方法;通过实践证明,本文所提出的深孔螺纹工艺方法不仅保证了加工工件的精度和质量,同时极大地提高生产效率,取得了良好的应用效果,为深孔螺纹加工技术提供了实用性参考。     

孔加工业的技术新篇

高效率孔加工对于促使零部件生产合理化是不可或缺的重要工艺过程。无论哪个领域的孔加工，实现高精度和高速化都是取得用户订单的重要竞争手段。     

浅谈孔径两端小中间大的深孔加工

深孔加工难度高、加工工作量大,已成为机械加工中的关键性工序。难切削材料的深孔加工及孔型复杂的深孔加工成为深孔加工技术中最为关键的问题。现列举了一"孔径两端小中间大的深孔加工"的实例,从加工难点、刀具设计及附件设计进行分析。     

新型小径深孔钻头

许多复杂机构的互换性将与小径深孔的加工精度有关。但是，在小径孔坐标尺寸的精度很高时，机构的尺寸互换性只有在钻头偏斜不大于±０．０１５mm时才可能。本文介绍几种新型小径深孔钻头，可保证这些孔的加工。１几种新型小径深孔钻头从生产经验得知，当钻头的刚性较小时，孔轴线的直线度只有当已加工的孔壁是钻头的导向时，即产生钻头自定心时才能保证。但是，自定心就在加工开始时建立。为此，一般采用钻套，使其孔的轴线与主轴的旋转轴线相重合，或者在工件内作精确的钻头引孔。（１）单边切削的叶片式钻头图１所示为不同结构的叶片式钻…     

套筒的孔镗加工工艺研究

<正>一般将孔的长度与直径之比大于5的孔,称为深孔。深孔加工比一般孔加工难度大。在汽轮机调节部套中存在一定数量的长套筒,如图1,不仅孔深(L/D≈12),而且对精度和表面粗糙度的要求也很高。由于零件较长,对深孔加工时常采用“一夹一托”的方法,但普遍存在下列问题:     

加工深盲孔的内冷却丝锥

内螺孔的孔形有两种 ,通孔和盲孔。加工深盲孔的难度比加工深通孔的难度还要大。如工件是难加工材料螺孔又是深盲孔时 ,那加工难度就更大了。1　内螺纹在加工中的难度( 1)它是在闭孔里切制成形内螺纹 ,切屑的排除比较困难 ,切屑易损伤已形成的完整螺纹。同时还容易产生切屑拥挤阻塞 ,卡住丝锥 ,致使螺牙裂断或丝锥折断。( 2 )润滑冷却剂的输入和排除都较困难 ,给顺利切削螺纹造成了不利影响。我们根据多年来对螺旋槽丝锥和内容屑丝锥的实际使用经验的总结和机理分析 ,为消除这些丝锥的不足 ,我们设计制造了一种直通容屑槽和内润滑冷却的丝锥…     

Value at Risk in the Suburbs: Eminent Domain and the Geographical Politics of the US Foreclosure Crisis

Several US counties and local governments have recently considered a novel solution to the foreclosure crisis. They plan to use eminent domain to compel the owners of mortgage debt—and specifically of private‐label mortgage‐backed securities—to sell the debt to the government at a price reflecting the loan's market value. The government would then restructure the debt and resell it to new investors. The plans are striking because—in contrast to both development‐driven eminent domain and the federal subprime bank bailout—they would force investors to assume asset devaluation and increased long‐term risk. Notably, the plans have emerged as an instance of financialization‐focused politics in suburbs and suburban cities of color, specifically majority‐black and ‐Latino/a suburbs. Local support for the plans, we argue, is rooted in the long‐term disinvestment of these ‘suburbs of exception', which became targets of subprime lending and eventually sites where the ‘financial exception' has been localized. But these demographic shifts, fragmentation and fiscal pressures have at the same time created a suburban political terrain in which the plans have gained their strongest political support.     

Towards a Theory of Serendipity: A Systematic Review and Conceptualization

Serendipity – the notion of making surprising and valuable discoveries – plays a major role in the success of individuals and organizations alike. Previous research has established the importance of serendipity and identified important individual- and organizational-level antecedents. However, the literature has been dispersed and the boundaries of the concept have been blurry, leading to a lack of conceptual clarity and structure, and thus limiting validity and managerial actionability. Based on a systematic literature review, I synthesize existing management-related research on serendipity and explicate the emergence and composition of serendipity in the organizational context. I first identify three necessary conditions that differentiate serendipity from related concepts such as luck or targeted innovation: agency, surprise, and value. Then, I draw from the literature on sensemaking, event-based theorizing, and quantum-based approaches to management to conceptualize the process of cultivating serendipity in the organizational context as a process of enabling potentiality and materialization, and develop a multi-level theory of (cultivating) serendipity. This conceptualization contributes to our collective understanding of how, why, and when (i.e., under what conditions) organizations can leverage the value in the unexpected, which opens up fruitful avenues for further research.     

Accountability of NGOs in Bangladesh A critical overview

NGOs in Bangladesh have been recognized as effective change agents in the socio-economic arena throughout the world. Their contributions in micro credit, non-formal education and primary health care are widely known. NGOs play a significant role in society. NGO accountability, as a result, has become a critical issue. NGO accountability in Bangladesh has been examined here in relation to patrons, clients and themselves. Of the three relationships only accountability to patrons is in a near satisfactory state. Accountability to clients is handicapped by lack of opportunities of beneficiaries to participate meaningfully in NGO policy making. Accountability to themselves is adversely affected due to the adherence to a strictly hierarchical system and the influence of founding and charismatic NGO leaders.     

Towards an Asian model of human resource management? A comparative analysis of China,Japan and South Korea

There has been much discussion regarding the possible decline and weakening of national systems of human resource management (HRM). Yet, culture and institutions are often cited as the major stumbling blocks to this outcome. Such constraints may dissipate in the analysis, particularly if ‘regional clusters’ are considered where geographic and cultural closeness and ‘openness’ to similar economic pressures exist. In such cases, it might be postulated that convergence in HRM will occur. We argue that China, Japan and South Korea represent such a cluster. This article examines these countries, to see if a degree of convergence is taking place and if it is towards an identifiable ‘Asian’ model of HRM. A model of change is presented that distinguishes between levels of occurrence and acceptance. Details of the development and practice of HRM in each country are then set out. The article ends with a discussion and implications section and a brief conclusion.     

The Creation of the Office for National Statistics

A new Office for National Statistics was created in the United Kingdom in 1996 following a series of developments designed to strengthen the relevance and integrity of statistics. This paper describes these fundamental changes and sets out a blueprint for future progress. It also sets current developments in the United Kingdom in an historical and international context.     

What helps? Women engineers' accounts of staying on

We have considerable understanding of the obstacles that women engineers encounter and the reasons that they leave the field, but we know less about what enables them to remain. Adopting an interpretivist approach, this article examines how a group of British women engineers in two FTSE 100 companies account for “staying on” in their male‐dominated work settings. We delineate four specific forms of help that facilitate women's retention in the field. We argue that exposure to help leads to women developing a habitus that enables them to continue working in engineering. To conclude, we draw on our findings to outline HR practices that will facilitate supportive relationships in the workplace and pave the way towards developing more positive organisational climates.     

论现代物流企业的发展观

物流业经过诸多年的发展目前已经成为最热门的行业之一,物流企业的注册数量也与日俱增,达到前所未有的规模。毋庸置疑,任何企业都希望自己迅速做强做大,并成为真正现代物流企业的典型代表,要实现这一目标一个首要问题就是要解决现代物流企业的发展观问题。     

浅谈大体积混凝土裂缝的控制

大体积混凝土的裂缝问题是实际工程中长期困扰工程技术人员的问题,其控制技术的研究是混凝土结构研究的热点问题,具有重大的学术价值和潜伏的工程背景。     

Supply Chain Strategies in the UK Fashion Industry—The Rhetoric of Partnership and Realities of Power

This paper focuses on the fashion industry, one characterised by issues such as dramatic shifts in the scale and power of major retail buyers in the market, the advent of retailer own brands, and the nature of sourcing and supply chain decisions, issues that are increasingly global in nature. The aim of this research is to explore the nature of relationships between UK high street multiple fashion retailers and their contracted suppliers, many of whom are entrepreneurial firms by most definitions of the term. Four core themes emerge from the literature and provide a framework for the research, namely, power, process, partnership, and people. The research approach was qualitative, and conducted over a period of twelve months. The paper ends with an agenda for future research.