平面一次包络环面蜗杆传动的啮合状态分析

本文对平面一次包络环面蜗杆传动不同β角下的接触线分布与啮会状态进行了分析．通过分析,指出β角对啮合状态有很大影响．     

精轧机压下装置平面二包蜗轮副参数优化

热轧精轧机压下装置传动机的轧机的重要部件，二级减速原品采用的是美国产Hindley蜗杆传动。经过改造后采用平面二次包络蜗轮副传动。分析了直廓环面蜗杆传动和平面二次包络蜗轮副传动的优点，并推导了平面二次包络蜗轮副传动接触线方程，在此基础上，通过对蜗轮副不同参数情况下接触线的分析，对蜗轮副参数进行优化，得到理想的接触线分布。     

平面一次包络环面蜗杆传动的啮合状态分析

本文对平面一次包络环面蜗杆传动不同β角下的接触线分布与啮合状态进行了分析。通过分析，指出β角对啮合状态有很大影响。     

渐开线齿轮包络环面蜗杆传动设计与制造

为适应机械传动传递功率及速度不断增长的需要,蜗杆传动技术得到迅速发展,出现了许多新型蜗杆传动,渐开线齿轮包络环面蜗杆传动就是其中之一。它与普通蜗杆传动相比,具有多齿接触、接触线形状有利于动压油膜形成等优点,使承载能力大大提高;它与直线齿环面蜗杆传动相比,具有加工工艺简单,不需要进行复杂的“修形”,也不必制造环面滚刀等优点。利用渐开线齿轮加工装备及刀具,便能获得较满意的效果,它与平面二次包络环面蜗杆传动相比,可以利用切削方式获得精确的包络型环面蜗杆齿面。渐开线齿轮包络环面蜗杆对于不需要     

圆柱蜗杆传动的新结构——双节点传动

以蜗杆啮合节点理论为基础提出一种圆柱蜗杆传动的新结构—双节点侧置双蜗轮传动；这种传动的特征是啮合性能得到很大的改善：以位置角等于９０°为例：同时接触齿数接近包络环面蜗杆传动，诱导曲率和润滑角则优于环面蜗杆传动。因其在已有的成熟的工程技术基础上发展起来的新技术，容易实现系列化设计，新产品开发和规模化生产，有取代包络环面蜗杆传动之势。     

平面包络环面蜗杆传动付的特性及装校

介绍了平面包络环面蜗杆传动付的成形原理和其具有体积小,承载能力大,传动效率高的传动特点,及装校要点。实践证明:采用观察接触斑点调整间隙的方法能使平面包络环面蜗杆传动时得到正确合理的应用。     

平面包络环面蜗杆理论及技术发展综述

平面二次包络环面蜗杆副由于其优异的性能成为当代蜗杆传动的皇冠,新型传动的代表.曲率修型原理的提出,解决了平面包络环面蜗杆的核心理论和最优齿形的问题;计算机技术在平面包络环面蜗杆的设计、制造中的应用取得了突破性的成果,优化设计和数字仿真解决了平面包络环面蜗杆副几何参数和工艺参数设计的难题;多年来一直成为平面包络环面蜗杆副推广障碍的参数系列化、标准化得到初步解决;滚刀CAD和辅助工艺设计极大地提升了工作效率;成套加工设备和工装的开发为平面包络环面蜗杆副的制造提供了良好的硬件;数控加工软件和技术的开发必将成就平面包络环面蜗杆的智能制造.新的理论和技术对环面蜗杆的推广应用将起到很好的促进作用.     

变β角平面包络环面蜗杆传动二次包络

此文以变β角母平面包络出来的蜗杆曲面为母面,对蜗轮齿面进行包络,获得变β角平面包络环面蜗杆传动二次包络的结果,从而建立了这种传动蜗轮齿面等的数学模型,为进一步进行啮合分析和生产实践创造了条件。     

平面二次包络环面蜗杆副的安装与调整工艺探讨

通过对平面二次包络环面蜗杆副啮合状态的分析 ,提出了平面二次包络环面蜗杆副的装配要求 ,并就常用的几种平面二次包络环面蜗杆副的装配方法作一介绍     

新型蜗杆传动——首钢—71型蜗轮副

首钢—71型蜗轮副是一种新型蜗杆传动,具有承受载荷大,传动效率高,使用寿命长等优点,体现着蜗杆传动科学研究的最新成果。在平面包络蜗杆传动中,威尔德哈泊型(Wildhaber Worm)和普拉那蜗轮(Plana Worm)是大家熟悉的。前者的蜗轮齿平面与其轴心线平行,后者的蜗轮齿平面与轴心线倾斜一个角度,在我们看来,二者都是平面一次包络的蜗轮     

不同类型塑料螺旋轮啮合强度研究（英文）

This study investigates the strength of plastic helical wheels meshed with enveloping and cylindrical worms whose tooth profiles mesh in line contact with helical wheels.R unning fatigue tests of plastic helical wheels together with a conventional cylindrical involute worm,a line contact enveloping worm,and a line contact cylindrical worm were conducted.T he tooth bearings,tooth temperatures,and fatigue lives of plastic helical wheels meshed with the different worms were examined at various center distances.Main results obtained are as follows:T he lives of both line and point contact wheels depended upon backlash,but the lives of line contact wheels are more sensitive to backlash than those of point contact wheels.At the backlash that maximizes the wheel life,the line contact wheels last longer than point contact wheels at smaller applied torques,but the influence of worm type on wheel life reduced at higher applied torque.     

圆柱面过盈联接仿真与验证

工程中常用圆柱面过盈联接来传递载荷,且过盈量的大小决定了传递载荷能力的大小。运用AN-SYS接触分析模块能有效地对该联接形式进行仿真分析,并运用相关理论证实其仿真结果的正确性。该仿真接触分析法同样适用于其它不同类型的过盈面联接型式。     

高效废铝再生熔炼炉组

本文的高效废铝再生熔炼炉组主要由熔化室、电磁循环泵、加料井、循环管路四部分组成.该炉采用电磁循环泵为铝液流动提供动力,使铝液在特殊结构的加料井中形成非接触式漩涡.该漩涡强度大,对铝屑的沉熔效果好,铝屑氧化烧损小,是一种技术先进、高效的废铝再生熔炼炉组.     

带增程机构液压梭式布料器的设计与应用

在分析了以往烧结机使用的梭式布料器换向方式存在问题的基础上,充分利用液压系统的特点,设计了一种带增程机构的液压梭式布料器配套于新设计开发的烧结机,并利用液压缸驱动双联绳轮小车实现布料小车增程一倍,缩短了液压缸的行程。布料器运行平稳,换向时无冲击,布料均匀,运行速度调节方便,能耗低,受到了用户的欢迎。     

装料机高速计数器速度控制的应用

简要介绍了Ф180无缝厂环型加热炉工艺,着重说明高速计数器在装料机上速度控制的应用方法.通过实际应用证明了该方案的实用性,并解决了装料机由于速度高停车时撞击前、后极限的现象,提高了生产效率,延长了设备寿命.     

Daily noninvasive rejection monitoring improves long-term survival in pediatric heart transplantation

BACKGROUND: Acute rejection episodes and transplant vasculopathy (TVP) account for most of the late deaths after heart transplantation in both adults and children. Accumulating evidence indicates that fatal acute rejection and TVP are related to unrecognized and untreated early and ongoing acute rejection. Day-by-day surveillance of the heart and prompt treatment of any rejection may yield improved long-term survival. METHODS: In almost all patients having transplantation at our institution (978 patients since 1986), the intramyocardial electrogram (IMEG) was recorded routinely every day through a telemetry pacemaker and transmitted to our center by telephone modem. Earlier studies showed a substantial voltage drop in the IMEG QRS complex is highly indicative of acute rejection, including humoral rejection. In this study, we reviewed the data from 69 pediatric patients up to 16 years old for the incidence of acute rejection, TVP, and long-term outcome. Diagnostic endomyocardial biopsies were performed in only 10 patients, and recent coronary angiograms from 29 children were reviewed. RESULTS: In 50 children discharged after heart transplantation, IMEG surveillance data for a mean of 2.9 years indicated 72 acute rejection episodes. During follow-up of 1 month to 10.5 years (mean follow-up, 4.4 years), 2 patients died late of causes unrelated to either rejection or TVP. Another patient died of rejection during unrecognized underimmunosuppression nearly 8 years after transplantation and nearly 31/2 years after discontinuing IMEG recordings. Two patients without IMEG recording died of acute rejection or late TVP. In 1 patient, moderate TVP was seen on an angiogram after 41/2 years (incidence, 2.0%; 5-year incidence, 5.6%). CONCLUSIONS: Daily recording of the IMEG can reliably detect early stages of acute rejection episodes, and immediate rejection treatment seems to keep the incidence of TVP low. The IMEG appears better than all the other rejection monitoring protocols currently in use.     

Electromagnetically and thermally driven flow phenomena in electroslag welding

Through the statement of Maxwell's equations, the turbulent Navier-Stokes equations, and the convective heat balance equation, a mathematical model has been proposed for the Electroslag Welding Process. In the formulation, allowance has been made for both electromagnetic and buoyancy forces for driving the slag and the metal flow. The principal finding of the work is that convection in the molten slag region has a marked effect on the heat transfer process. For a rectangular geometry, using plate electrodes, the flow field is driven by buoyancy forces, the circulating flow is less intense, and the thermal efficiency of the process is improved. In contrast, for wire electrodes (approximated by a cylindrical geometry) the flow is driven by electromagnetic forces and a substantial part of the thermal energy is dissipated to the plates. A. H. DILAWARI formerly Visiting Engineer at the Massachusetts Institute of Technology.