煤矿机械传动齿轮失效原因及解决方法

煤矿机械设备事故率较高一直是严重困扰我国煤炭生产和运输的重要因素之一，而传动齿轮失效是这些事故中最常见的原因之一。煤矿机械齿轮的失效形式有轮齿折断、齿面胶合、齿面点蚀和齿面塑性变形等。文章针对煤矿机械的工况和环境特点，分析了常见的几种齿轮失效的原因，对于设计、制造和使用过程中如何避免或延缓这些齿轮的失效提出了改进的途径。     

机械传动齿轮失效的改进方法

煤矿机械齿轮的失效有轮齿折断、齿面胶合、齿面点蚀和齿面塑性变形等主要形式。由于轮齿啮合不合理，造成超负荷或冲击负荷而产生轮齿较软齿部分金属的塑性变形，严重时在齿顶的边棱或端部出现飞边、齿顶变圆，主动齿轮的齿面上有凹陷，被动齿轮的节线附近升起一脊形，使齿面失去正确的齿形。齿轮失效直接影响着煤矿机械效能的发挥，亟待解决，本文提出几种改进途径，针对煤矿机械功率大、速度低、重载和相对尺寸小的特点，分析了煤矿机械传动齿轮的失效形式，提出了改进途径。     

齿环式同步器的原理、结构、基本概念及其设计计算

文章介绍了变速器齿环式同步器的工作原理、常见结构及设计和实际分析问题过程中常用到的基本概念,对同步器实现同步功能的条件进行理论分析,在此基础上选择与确定同步器的主要设计参数,并总结了同步器设计过程中应关注的几个要点。     

齿环式同步器的原理、结构、基本概念及其设计计算

文章介绍了变速器齿环式同步器的工作原理、常见结构及设计和实际分析问题过程中常用到的基本概念,对同步器实现同步功能的条件进行理论分析,在此基础上选择与确定同步器的主要设计参数,并总结了同步器设计过程中应关注的几个要点。     

机械齿轮失效原因分析

齿轮失效一般可分为轮齿折断和齿面损坏两大类,轮齿折断属于轮齿的体积强度问题,齿面损坏则主要是齿面强度问题,齿轮的其他部分,如轮毂、轮幅和轮缘等,一般很少发生破坏。本文论述了齿轮失效的各种形式,分析了产生的原因,提出了切实可行的解决方法。     

机器设备中常见的齿轮失效分析及预防措施

齿轮传动是利用两齿轮的轮齿相互啮合进行传递运动和动力的机械传动。是最重要的传动形式之一,应用非常广泛。在生产使用过程中,由于工作实际情况和人为的操作不当常常会引起如轮齿折断、齿面点蚀等失效导致设备不能正常工作。本文针对齿轮传动过程中常见的失效形式、引起齿轮失效的主要因素及预防齿轮失效的措施进行分析。在分析过程中,针对引起失效的原因提出能改善齿轮传动质量,延长机器使用寿命的措施。     

粉末高速钢与分齿型硬质合金带锯条锯切钛合金失效模式分析

文章通过对粉末高速钢和分齿型硬质合金带锯条锯切钛合金的对比实验,分析了两种带锯条不同的失效模式。粉末高速钢带锯条主要是齿尖侧面磨损失效,而硬质合金带锯条则表现为背部疲劳失效,通过实验也表明两者的锯切效率和工具寿命相差很大。     

重型机械变速箱锁销式同步器常见故障模式的原因分析及解决方法

目前,国内中、重卡多采用主副箱结合的机械式变速箱,副箱使用锁销式同步器。用于高低档转换的锁销式同步器,适合于空间较大、需要传递大扭矩的副箱,其性能直接影响变速器能否顺利实现换档。通过理论分析、故障件拆解、实车跟踪等方法,文章分析了重型变速器锁销式同步器在使用过程中常见的故障模式,产生故障的原因,并提出了相应的解决办法。     

门机回转机构齿轮、齿圈和滚道修复工艺的研究和实践

针对门机回转齿轮和齿圈轮齿严重磨损、塑变和断裂的状况,以及滚道淬火层表面出现的开裂、压碎、剥落等损伤和破坏的情况,分析了轮齿、滚道失效和啮合失效的原因,对齿轮齿圈滚道修复的焊补和啮合的精度调整方案进行了分析和技术实践,通过对门机回转机构现场焊补和调整作业,取得了最佳的工艺实践成果和巨大的经济成本效益。     

门机回转机构齿轮、齿圈和滚道修复工艺的研究和实践

针对门机回转齿轮和齿圈轮齿严重磨损、塑变和断裂的状况,以及滚道淬火层表面出现的开裂、压碎、剥落等损伤和破坏的情况,分析了轮齿滚道失效和啮合失效的原因,对齿轮齿圈滚道修复的焊补和啮合的精度调整方案进行了分析和技术实践,通过对门机回转机构现场焊补和调整作业,取得了最佳的工艺实践成果和巨大的经济成本效益.     

论手动后驱变速器的同步器布置形式对同步性能的影响

文章描述后驱手动变速器的换挡过程,分析变速器同步器性能与操纵舒适性之间的关系,进一步阐述同步器的同步性能指标包含同步时间t_E和同步力Pa,探讨t_E和Pa与同步器布置之间的关系。     

桥梁预应力管道摩阻、锚口摩阻和喇叭口摩阻测试研究

文章详细介绍了结构物后张法预应力摩阻损失的测试方法及内容,准确测定预应力的实际摩阻损失,为确定钢绞线的张拉力提供了重要依据,使结构满足设计要求。测试时还对采用的方法、技术进行了改进,采用压力传感器和仅在一端设千斤顶的方法,比以往采用主被动千斤顶、油表读数的测试方法精度更高、方法更合理。     

Knowledge acquisition using psychotherapy technique for critical factors influencing construction project layout planning

The positioning of equipment on a construction site may change in different construction phases, different environments, and different types of end products, which greatly influence the decision of the site planning engineer who seeks to maximize the construction efficiency by minimizing the friction from the site layout. This study aims to acquire and analyze site planning experts' knowledge on critical factors influencing the construction layout planning using a psychotherapy technique. Through an open‐structured interview survey and cluster analysis, 125 core factors influencing the site layout plan were analyzed and categorized into a database.     

Subsidiary staffing,cultural friction,and subsidiary performance: Evidence from Korean subsidiaries in 63 countries

Drawing from the notion of cultural friction and based on the agency theory rationalization of multinational enterprise (MNE) headquarter–subsidiary relationship, we examine the impact of cultural friction in foreign subsidiaries on subsidiary performance. We argue that cultural friction, arising due to a high presence of parent country nationals (PCNs) in culturally distant locations, has a detrimental effect on subsidiary performance. This effect is the strongest when the cultural friction is at the top management team (TMT) level and the weakest when friction is at the regular employee level. However, this relationship is contingent on factors that work as drags or lubricants for cultural friction between PCNs and host country nationals (HCNs). We identify governance mode and language differences between home and host countries as drag parameters and host country experience and subsidiary interdependence as lubricants that condition the effect of cultural friction on subsidiary performance. Empirical findings based on a longitudinal sample of 7,495 foreign subsidiary observations of 467 Korean MNEs in 63 countries during 1990–2014 provide robust support for our theoretical predictions.     

球轴承联合载荷动态摩擦力矩测量仪设计

滚动轴承在使用时,由于套圈、滚动体、保持架之间存在摩擦力,由摩擦力产生的阻力矩又称摩擦力矩。轴承摩擦力矩是影响轴承噪声、振动和寿命的重要因素,是衡量轴承动态性能的重要指标。文章所介绍的摩擦力矩测量仪是对深沟球轴承在轴向载荷和径向载荷的联合作用下测量轴承转动时的动态摩擦力矩。利用本仪器可以对轴承进行摩擦力矩的平均值、最大值、最小值和变动范围进行自动化检测。     

The difference that difference makes in the mobilization of workers

Drawing conceptually from feminist, post–development, cultural politics and radical political science literatures, this essay integrally relates differences among contexts (relationally defined) and people. I suggest that prospects for the mobilization of workers across space requires critical thinking about difference, entailing recognition of different work experiences associated with different industrial processes and avenues of exploitation, as well as possible friction among different groups of people across axes of difference. Although frictions of difference related both to economic and non–economic logics may pose complex problems for connecting workers within and across space, I argue that inclusive organizing strategies are critical to achieving pervasive and long–run social change. Tirant ces concepts de documents sur le post–féminisme et le post–développement, et de textes de politique culturelle et de science politique fondamentale, cet essai associe toutes les différences de contextes (définis en termes de relation) et d’individus. Il suggère que mobiliser des salariés à travers l’espace nécessite une réflexion critique sur la différence, ce qui implique la reconnaissance d’expériences professionnelles diverses combinées à des approches et processus industriels d’exploitation différents, ainsi que d’éventuels points de friction entre divers groupes de personnes d’un bout à l’autre des axes de différence. Même si ces points de friction, liés à une logique tant économique que non–économique, sont susceptibles de créer d’importantes difficultés pour relier des salariés dans l’espace, il faut appliquer des stratégies d’organisation globales si l’on veut obtenir un changement social capable de s’imprégner durablement.     

Pre-assigned rents and bureaucratic friction

In this paper we study the endogenous determination of bureaucratic friction in a bureaucratic contest with () and without (n = 1) rent contestability. When n= 1 bureaucratic impediments induce the individual to undertake rent-securing activities at the same level as in the two-player rent-seeking contest. However, under rent contestability the bureaucracy no longer serves as a means of extracting resources from the public. The paper concludes with the study of the effect of ‘net costs’ on bureaucratic friction. It turns out that under cotestability the only reason for creating bureaucratic friction is the ‘negative costs’ it incurs while when n = 1 the effect of the bureaucrat's net costs of generating bureaucratic friction on the optimal degree of such friction is ambiguous. Received: October 30, 2000 / Accepted: December 28, 2001 RID="*" ID="*" The authors are grateful to two anonymous referees for their valuable comments