罗茨泵转子实际型线公式的推导与计算

本文对渐开线型线罗茨泵转子的理论型线、实际型线公式做了新的推导。给出了转 子型线在直角坐标系第一象限内三段曲线的坐标方程式，列出了计算机程序框图，给 出了实例结果。这对罗茨泵转子的加工和检查具有一定的指导和帮助作用。     

圆弧-摆线-渐开线型罗茨泵转子型线参数选择范围

罗茨泵转子型线是罗茨泵的关键。零流量压缩比高的罗茨真空泵、湿式罗茨泵真空泵和罗茨鼓风机均要求泵工作时转子与壳体之间及两转子之间气体泄漏较小，这样可改善泵的低压下性能，即提高泵的抽气效率。转子型线为“圆弧－摆线－渐开线”就可以满足这一要求。文中给出了泵的参数选择图，从图中可以看出泵的参数选择范围，文中说明了该图边界的性状．由该图可查出泵的容积利用系数λ同转子顶圆半径Ｒｍ与节圆半径Ｒ之比 Ｒｍ／Ｒ以及同渐开线压力角α的关系。 λ＝ｆ（Ｒｍ／Ｒ，ａ）。图中用计算机绘出了几个比较特征参数下转子型线及其啮合情况，借此可根据实际需要来选择系的转子型线参数。此种转子型线工艺性良好。可仿型法加工（只需两个工位）。还可以用范成法加工其渐开线部分，余下部分用成型铣刀加工。若以范成法加工型线渐开线部分时，设计转子型线时可选取渐开线基圆半径ｒ为整数．以便于其工艺装备的设计。     

关于真空泵基础压力与罗茨真空泵特征性能指标的探讨

本文阐述了真空泵的极限压力与基础压力两者的概念和关系,对国际标准ISO21360-1:2012中有关基础压力的条款做了详细的解读。对影响中真空罗茨泵抽气性能的特性指标进行了分析,给出了用罗茨泵零流量压缩比K0和最大允许压差作为罗茨真空泵的抽气性能指标的合理性,建议选择罗茨泵零流量压缩比K0作为罗茨泵抽气能力的主要考核指标之一,将最大允许压差作为罗茨泵的辅助考核指标。     

罗茨真空泵试验方法的研究

罗茨泵的抽气速率和极限压力是泵的主要性能,但它在很大程度上要依赖于前级泵的型式和性能,因此它并不是罗茨泵本身特有的性能。能代表罗茨泵特征性能,而又与前级泵无关的是零流量压缩比、最大允许压差与溢流阀压差、漏率和噪声,它们与罗茨泵的真空状态、抽气性能和运行质量有着极其密切的关系。文中对特征性能的试验方法和装置进行了分析和研究,提出了有异于国内外现行标准的,更精粹、独特的见解。     

罗茨真空泵噪声机理探讨

在简要地介绍了罗茨泵工作原理的基础上,通过对罗茨泵主要零部件的分析,以及在使用不同轴承时产生噪声的原因进行了探讨.提出降低上述噪声的相应措施.同时对罗茨泵机体发热也作了简要的说明.     

罗茨真空泵的溢流阀与旁通阀的组合

在简要地介绍了罗茨泵功能的基础上，通过溢流阀的改进设计，使溢流阀成为既能旁通又能溢流的组合阀，罗茨泵的功能将更加完备。     

液力传动在罗茨真空泵上的应用

论述了液力传动的基本概念,对罗茨真空泵中常用的直联传动、皮带传动和磁力传动进行了分析,着重指出将液力传动应用到罗茨泵上以后,将使罗茨泵更能显示出其独特优异的性能。介绍了适合在罗茨泵中应用的静压泄液式(带阻流板)限矩型液力偶合器的限矩原理和基本结构,并突出了应对罗茨泵严格的限矩要求所采取的措施。     

罗茨真空泵性能考核指标——抽速和零流量压缩比的探讨

罗茨泵以抽速作为主性能考核指标不够确定，它不能真实反映罗茨泵的质量水平，建议以零流量压缩比作为考核罗茨泵抽气能力的性能指标。     

特殊类型的罗茨真空泵

本文简略地介绍了近几年来我所设计和研制的三种特殊类型的罗茨真空泵，即１５０Ｌ／ｓ双级罗茨真空泵、３００ Ｌ／ｓ真空电机罗茨泵、 ６００Ｌ／ｓ屏蔽电机罗洪泵这三种泵。相应地解决了目前生产的普通罗茨泵很难解决的问题。１５０ Ｌ／ｓ双级罗茨泵的研制成功，就解决了普通罗茨泵不能在高压强下运转的问题，它不但可以在高压强下运转，而且可以从大气下启动。３００Ｌ／ｓ真空电机罗茨泵能很好的解决动密封泄漏问题，泵低压运行又提供了安全可靠的条件。６００Ｌ／ｓ屏蔽电机罗茨泵同样很好的解决了动密封泄漏问题，又可在常压下运行，给用户带来一些方便条件。这三种泵的性能又都优于普通的罗茨泵，笔者认为这三种泵今后会更有发展前途的。     

滑阀真空泵,罗茨真空泵及其真空机组

滑阀真空泵、罗茨真空泵及其真空机组谈治信（兰州物理研究所，兰州７３００００）分类号：ＴＢ７５２滑阀式真空泵（简称滑阀泵）和罗茨真空泵（简称罗茨泵）及其由该泵组成的真空机组近几年来随着真空冶金、真空热处理、真空冷冻干燥、真空镀膜等各种领域的发展需要而得...     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.