数控车床加工中编程的原则与工艺优化技术分析

在数控加工中,不管是手工编程或者自动编程方式的应用,都需要对加工零件的零件图进行分析,对机床、夹具和刀具等进行合理选择,对数控加工的加工工艺方案合理确定。在数控编程中处理工艺问题的质量,不仅会对机床效率的发挥产生影响,零件的加工质量和生产效益也会受到影响,需要引起人们足够的重视。文章分析了数控车床加工中编程的原则与工艺优化技术,希望可以提供一些有价值的参考。     

基于HyperMill虚拟机床的建立与仿真

HyperMill自动进行干涉避让,为五轴刀路进行准确验证,进一步保证了五轴加工的安全性,避免机床干涉,刀具干涉,夹具干涉等。提出一种通过NX建模导出stl格式模型进行建立虚拟机床,实现了机床仿真模拟加工,采用HyperMill自带的HyperVIEW进行模拟仿真,大大提高了五轴加工效率。     

基于UG的变螺距螺旋槽建模及数控加工编程

文中阐述了用UG的参数公式方法进行变螺距螺旋槽零件的立体建模,并应用UG软件自动编程方法编制螺距螺旋槽零件在四轴加工中心机床上的加工程序,比较分析了各种切削参数设定和加工工艺方法运用。     

浅谈台阶轴零件机械加工工艺规程设计

台阶轴广泛应用于各类机械产品中,其加工工艺是否合理、可行等直接影响产品的质量。文章依据机械加工工艺规程的步骤,针对台阶轴零件的机械加工工艺规程进行设计,阐述了机械行业典型轴类零件的机械加工过程的前期准备工作,制定了机床、刀具、量具、毛坯等的选择及工艺路线,列出了相应的机械加工工艺过程卡片和刀具卡片。     

超长丝杠的加工综述

机床丝杠是机床上的传动部件,它将均匀的旋转运动精确地转换为均匀的直线运动.它不仅要准确地传递运动,而且还要传递一定的转矩.因此精度、刚度和耐磨性都有极高的要求.我们在工作中,经常会碰到丝杠严重磨损需要重新加工的情况,或是一些自制机床较特殊丝杠的加工.如按照常规工艺加工,工序多,流程长,需要的设备也较多;特别是加工周期长,还会影响机床的按时修复,从而影响生产.加之,如果没有较长轴的外圆磨,没有专门的螺纹加工机床,那么外协加工就会增加成本,延长生产周期.因此,对于超长丝杠,都尽可能的选择在普通车床上加工完成.在加工中,为增加工件的刚性和防止热变形,我使用了中心架、跟刀架和弹性伸缩顶尖;为减小车削时径向力的影响,防止振动,采用合理的车刀几何形状;为提高螺纹的加工效率,粗车时采用了"郭嘉明高速车削蜗杆法",缩短了粗加工时间.此加工方法比原加工方法提高生产效率30%.由于采用了正确的方法,保证了工件质量,缩短了生产周期,降低了加工成本,也为企业节约了开支.     

细长轴切削加工技术分析

车削细长轴具有大长径比,所以在切削力的影响下会存在弯曲震动、变形的问题,增大了细长轴切削加工工艺难度.通过分析细长轴切削加工过程中的夹紧方式、切削参数、误差补偿等技术研究,有助于提升细长轴切削加工技术水平,合理地运用不同切削加工方案,更好地指导细长轴加工工艺实施.     

论数控车轴类零件的工装与加工路线设计

本设计以数控车床轴类零件车削为例,根据被加工工件的材料、轮廓形状、精度等要求进行工艺分析,选用合适的机床、刀具、夹具及加工路线。     

如何选择轴类零件的定位基准

轴类零件定位基准的选择是制定加工工艺的重要步骤。文章在分析典型的轴类零件的结构、技术要求的基础上,与实际的加工过程相结合分析定位基准的选择,制定合理的加工工艺。     

数控机床加工工艺分析和精度分析

近年来我国的数控机床技术正处在突飞猛进地阶段,在数控机床的使用过程中,加工工艺分析和精度分析对于机床的加工效率和零件的加工精度都有重要影响,文章研究了数控加工工艺的主要步骤和精度研究中容易出现的问题以及解决方法,以期对数控机床的加工工艺研究有一定的促进作用。     

304不锈钢吊装门五金连接件铣削加工工艺分析

文章介绍了校企合作生产中,在加工中心机床上批量加工304不锈钢零件的工艺过程,分析和总结了不锈钢吊装门零件铣削加工工艺。     

Incumplimiento del salario mínimo en Europa central y oriental

En este estudio se analiza el incumplimiento del salario mínimo durante el periodo 2003–2012 en diez países de Europa central y oriental con salario mínimo obligatorio nacional. A partir de los datos de EU‐SILC y la metodología propuesta por Bhorat, Kanbur y Mayet (2013), se cuantifica la incidencia y magnitud del incumplimiento. Se realizan análisis de regresión sobre determinantes individuales, laborales y macroeconómicos. Aunque la incidencia permanece relativamente baja, los trabajadores a los que se dirigen las políticas de salario mínimo parecen los más expuestos a su incumplimiento. Con el tiempo, una mayor incidencia se asocia a una razón más alta entre salario mínimo y salario medio.     

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.     

Cultural Economy Planning in Creative Cities: Discourse and Practice

While a growing body of research analyses the functional mechanisms of the cultural or creative economy, there has been little attention devoted to understanding how local governments translate this work into policy. Moreover, research in this vein focuses predominately on Richard Florida's creative class thesis rather than considering the wider body of work that may influence policy. This article seeks to develop a deeper understanding of how municipalities conceptualize and plan for the cultural economy through the lens of two cities held up as model ‘creative cities’ — Austin, Texas and Toronto, Ontario. The work pays particular attention to how the cities adopt and adapt leading theories, strategies and discourses of the cultural economy. While policy documents indicate that the cities embrace the creative city model, in practice agencies tend to adapt conventional economic development strategies for cultural economy activity and appropriate the language of the creative city for multiple purposes.     

Input/output ranges and performance: an examination of US machine tool producers

Despite the establishment of high-tech multinational enterprises (MNEs) in Ireland since the late 1950s, the country did not succeed in closing the technological gap with most of its EU counterparts. The weak National System of Innovation (NSI), and in particular low business and government R&D levels, combined with a lack of research and technology linkages between MNEs and indigenous firms, explain these poor results. However, the Shannon region in the West of the country presents some specific institutional characteristics that could theoretically make the region a strong technological enclave. The various actors in the region - i.e. the administrative, financial, political and research institutions, as well as the business organizations - have indeed infused a new type of economic development. After a brief review of the available concepts and models articulated around these actors and their interrelationships, the paper analyses whether the Shannon region, taken as an illustrative example, mirrors a specific economic and technological localized setting. The study is based on a survey of indigenous and foreign firms.     

Sixty years of discrimination and diversity research in human resource management: A review with suggestions for future research directions

This article reviews discrimination and diversity research published in Human Resource Management (HRM) over the past 60 years. While discrimination and diversity are very different constructs, it is often informative to study them together, because when people recognize each other's diversity, this can result in bias, stereotyping, and discrimination. We conducted bibliographic searches for terms related to discrimination and diversity as well as a manual search through every title and abstract published in HRM over the last 60 years to assess article relevance. The search resulted in 135 research articles with 136 unique studies (i.e., samples) which are reviewed in this article. Sex and race are the demographics that have been examined the most in HRM, while religion has been examined the least. Moreover, the number of studies examining lesbian, gay, bisexual, transgender, and queer (LGBTQ) employees in the workplace in HRM has grown quickly within the past 10 years, culminating in a recent meta‐analysis. Our review looks at some of the earliest research published, the most recent research published, and the overall trends we identified in the research over the years for both discrimination and diversity articles. We then make future research suggestions and recommendations to advance the study of discrimination and diversity in the coming years.     

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 Early History of the Cumulants and the Gram-Charlier Series

The early history of the Gram-Charlier series is discussed from three points of view: (1) a generalization of Laplace's central limit theorem, (2) a least squares approximation to a continuous function by means of Chebyshev-Hermite polynomials, (3) a generalization of Gauss's normal distribution to a system of skew distributions. Thiele defined the cumulants in terms of the moments, first by a recursion formula and later by an expansion of the logarithm of the moment generating function. He devised a differential operator which adjusts any cumulant to a desired value. His little known 1899 paper in Danish on the properties of the cumulants is translated into English in the Appendix.     

Capturing the Implications of Services Trade Liberalization

This paper evaluates the impact of service sector trade liberalization on the world economy by a ten-region, eleven-sector CGE model with import embodied technology transfer from developed countries to developing countries. Simulation results show that service sector trade liberalization not only directly affects world service production and trade, but also has significant implications for other sectors in the economy. The major channel of the impact is through inter-industry input-output relations and TFP growth induced from services imported by developing countries from developed countries, which may be embodied with new information and advanced technology.