位置尺寸合成误差的计算

阐述了在机械设计和计算中对不是互相平行的，而是互成一定角度，分布在一个或几个平面内的位置尺寸，如何由位置尺寸各组成环的公差计算其合成误差，或由限定的合成误差来确定各组成环的公差，计算采用极大极小法求解方法。     

“尺寸跟踪法”在活塞设计和加工上的应用

为了满足活塞的使用功能,并用经济合理的办法将其制造出来,除在设计制造时,对活塞结构、材质和表面质量给予重视外,还应重视合理确定精度要求,以控制尺寸、形状、表面位置误差的范围。 就尺寸公差的控制而言,需要设计人员进行严格而认真的计算,井在产品图样上合理地标注尺寸及公差,同时,工艺人员需结合本厂的生产条件,制定出能生产合格成品的较优方案,将加工过程及顺序、工序尺寸和公差标注在工艺文件上。这是一个复杂而仔细的工作过程。特别是活塞裙部轴线方向上,各道环槽侧面、燃烧室底面、销孔轴线对顶面的距离等处均有严格要求,并都需经过粗精加工阶段的若干道工序将其加工出来,基准多次转换,误差层层累积,使这类工序尺寸及公差的计算、余量的确定增加了难度。 从一九八四年起,我们将《尺寸跟踪法》这一计算工艺尺寸链的新方法,应用于活塞设计和工艺设计过程中,较以往用单个尺寸链法或经验法进行计算要简洁、明瞭、可靠,优化了设计工作。     

气门盘锥面高检测方法探讨

在讨论气门盘锥面高度尺寸检测方法之前,应首先搞清楚气门盘锥面高度尺寸公差与气门盘端面形位公差之间是什么关系。有不少设计、制造和检测人员截止到今还没有重视这个问题。在标注、制造和检测气门盘锥面高度尺寸公差时,有一个遵循什么公差原则的问题,公差原则主要指尺寸公差与形位公差的相互关系,规定了公差原则,就可以使气门的设计、制造、检测三者统一起来。因此,它在形位公差新国标中占很重要的位置。 在《内燃机配件》杂志上经常发表气门盘锥面高度尺寸公差的检测方法文章进行讨论,但至今还很少发表文章讨论气门盘锥面高度尺寸公差与气门盘端面形位公差之间是什么关系的文章。 在《内燃机配件》杂志九六年第二期,由蓬莱动力机械配件厂张敬源等三位专家,写了一篇文章,题目是《气门标准化设计探讨》。提到了气门盘锥面高度尺寸公差是否包客盘端面形位误差的问题,还提到凡尔线到盘端面高度尺寸是指高点位置尺寸,还是指低点位置尺寸的问题。我们觉得这个问题提的好,很有必要进行讨论。下面谈谈我们的意见供行家们讨论,想通过我们这篇文章起到抛砖引玉的作用。     

气缸套支承肩位置公差及检测

1 前言 气缸套支承肩的位置误差,是影响气缸套可靠性的重要因素。位置误差超过公差,可能在气缸套装配式使用中,支承肩发生断裂,引发恶性事故。本文通过生产中对气缸套位置公差的检测,浅析有关位置公差中的一些问题,供同行参考。     

在上海召开铝活塞技术条件第二次修订工作会议

八一年一月八日至十二日,在上海活塞厂召开了第二次GB＇148-74修订工作会议。参加会议的有23个单位30名代表。与会同志本着认真负责的精神,详细讨论了“铝活塞技术条件修订草案供讨论稿”,特别对铝活塞各部位名称、材料、主要部位的光洁度、环槽的位置公差、销孔的尺寸公差和形位公差、裙部的形状公差等     

柱塞斜槽形位公差的若干标注方法及其误差的正确评定

柱塞斜槽的形位公差,在国标、部标及国内、外企业产品图样和工艺文件中出现若干不同的标注方法。常见的有以下两种控制方法: 1.以直线度控制形状误差,以斜槽大、小油量处两点尺寸控制斜槽位置,简称“两点法”。 2.以倾斜度或线轮廓度控制综合形位误差。 本文剖析不同标注方法的含义以及误差的正确测量和评定方法。     

活塞校对环规检测方法的改进

在活塞销孔加工工序或成品检验中,需要用到气动量仪来测量销孔直径及圆度误差,而使用前,须用校对环规调整气动量仪的零件和倍率。针对我厂生产的活塞机型。校对环规公称直径为φ17～φ50mm,尺寸公差为±0.0015mm,圆柱度公差0.001mm(这种直径既小精度又高的校对环规,以下简称小环规)。根据我们厂生产特点及管理办法,工具分厂新制小环规,活塞专业厂及检查处外购新入厂的小环规,以及加工生产线换机型等需要周期检定的小环规,均要送到计量室进行检定,计量室每月平均要检定的小环规数量是25件左右,相对于检测难度较大的工件来讲,数量较大。     

平行孔系坐标尺寸公差的全微分计算

平行孔系坐标尺寸公差的传统计算方法是把各尺寸投影到某一确定的方向上，把平面尺寸链转化为线性尺寸链，用线性尺寸链计算公式进行计算。现在通行的《机械制造工艺学》教材也仅仅介绍投影法计算。这种计算方法往往较为繁琐。把微分计算公式引入工艺计算则可克服传统计算方法的不足．该方法不需要进行尺寸链的转化，可减少计算误差的影响，且适于运用微机编程计算。     

柱塞斜槽形位公差的若干标注方法及其误差的正确评定

柱塞斜槽的形位公差，在国际、部标及国内、外企业产品图样和工艺文件中出现若干不同的标注方法。常见的有以下两种控制方法：１．以直线度控制形态误差，以斜槽大、小油量处两点尺寸控制斜槽位置，简称“两点法”。２．以倾斜度或线轮郭度控制综合形位误差。本文剖析不同标注方法的含义以及误差的正确测量和评定方法。     

基于润滑的曲轴径向圆跳动公差设计

分析了径向圆跳动误差对主轴承润滑的影响机理,提出一种基于润滑的公差设计方法;建立润滑仿真模型计算了主轴颈径向圆跳动公差,并对比分析了不同方案下的设计结果.研究表明:径向圆跳动误差导致轴承径向承载空间大小发生改变,其分布形式改变曲轴实际旋转轴线的位置,这些都影响主轴承的润滑性能;采用旋转轴线为跳动最大值和最小值中线的方案,公差设计效果最佳;基于润滑的公差设计方法能够较好地解释引进机型的跳动公差精度要求,可应用于内燃机曲轴形位公差设计.     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

促进城镇生活污水处理装置产业化

城镇生活污水处理装置是由农村户用沼气地发展演变而来，是一种小型、分散化处理污水的装置 ，是环境建设的需要。文章着重从我国环保政策及目标、生活污水造成的污染状况、急需整治的公共设施、生活污水净化装置的演变以及社会经济效益和环境效益等方面，阐述了其产业化的重要性。     

Impact of nanostructuring on the enthalpy of formation of metal hydrides

High-energy ball milling has been shown to decrease the release temperature, increase the reaction kinetics, and lower the enthalpy of formation of metal hydrides in certain cases. This paper discusses several potential mechanisms for the reduction of the enthalpy of formation. Although the increased surface and grain boundary energy could play a role in reducing the enthalpy of formation, the predicted magnitude is too small to account for experimental observations. Structural deformation and the associated volume change provide another mechanism for the change in this thermodynamic property. We employed three equations of state models to characterize the excess energy present in the deformed regions and found that the excess volume provides a plausible explanation for the experimentally observed change in thermodynamic properties.     

煤中钾存在形式研究

煤中钾的存在形式与煤的灰污性质密切相关。通过萃取的方法,分别以水、醋酸铵和稀盐酸为萃取液对钾在我国一些煤中的存在形式进行了研究。结果显示,煤中钾除了以硅铝酸盐形式存在外,还有其它多种存在形式,尤其在低阶煤中,其它形式的钾占有显著份额。钾在煤中存在形式与煤种、煤阶、煤的显微组分和煤粒径有关。     

脱硫工艺水泵运行的分析及对策

通过对日常生产过程中脱硫工艺的水泵运行方式分析,解决实际工作中的小问题,也能取得不错的节能降耗的效果。主要针对发电厂脱硫工艺水系统多用户且用户数不定的水泵运行现状分析,抓住主要因素,在平常工作中,采取改变运行方式等简单有效的措施,达到节能降耗,降低设备故障的目的。在一年多的运行实施过程中,得到了验证,取得了不错的效益。     

Approbation of an innovative method of pretreatment of dark fermentation feedstocks

According to the International Energy Agency, only a small part of the full potential of biomass energy is currently used in the world. The annual amount of agricultural waste in the Russian Federation is estimated at about 152 million tons, and the energy potential of animal waste is 201 PJ/year. Anaerobic digestion is an efficient method of converting organic waste into renewable energy sources. Previously, the positive effect of pretreatment of various organic feedstocks in vortex layer apparatus (VLA) on the characteristics of anaerobic digestion and energy efficiency was shown. Currently, there is a significant interest in the world in obtaining biohydrogen from organic waste using the dark fermentation (DF) process. During pretreatment in the VLA, the iron working bodies are abraded and iron particles are introduced into the feedstock of the DF reactor. This may have a positive effect on the production rate and yield of hydrogen, which has not been previously studied. This work is aimed at evaluating the possibility of using the VLA as a method for pretreatment of a dark fermentation feedstock for the intensification of biohydrogen production. To achieve this goal, an experimental setup was constructed. It consisted of a 45 L DF reactor, a VLA and a process control system to collect data on the DF process parameters every 5 min. At a hydraulic retention time in the DF reactor of 24 h and in the VLA of 30 s, the hydrogen content in the biogas increased from 51.1% to 52.2%. At the same time, the pH increased from 3.85 to 4.8–4.9, and the hydrogen production rate increased by 16% to 1.941 L/(L day). The hydrogen yield was 80.9 ml/g VS. Thus, pretreatment of the feedstock in VLA can be an effective way to intensify the DF process; however, further study of the VLA operating modes is required in order to optimize the concentrations of iron particles introduced into the feedstock for the most efficient continuous production of dark fermentative biohydrogen.     

Recommendations for implementation of energy strategy of the Republic of Croatia

The Energy Strategy of the Republic of Croatia was adopted by the Croatian Parliament in 2009 for the period until 2020 in order to harmonize national energy goals with goals and time framework of strategic documents of the European Union. The adoption of the Energy Strategy Implementation Program with associated measures is still in process. The goal of the Strategy was to create sustainable energy system that will make a balanced contribution to the security of energy supply, competitiveness and environmental protection in Croatia. In this paper an overview of the energy production, final energy consumption and planned development of energy infrastructure is given. The intention of the paper was to research and stress out the abilities and opportunities of Croatian energy system and to give recommendations for Energy Strategy implementation and practical realization of planned energy infrastructure projects for improvement of security of energy supply and competitiveness of energy system of the Republic of Croatia.     

变频器节能作用概述

节能减排是摆在世界人们面前的亟待解决的大问题,变频器在工业生产和生活中的广泛应用为节约能源起到了巨大作用。变频技术最早应用于无线通信系统,为无线通信技术的发展发挥了巨大作用。上世纪80年代,变频技术广泛应用于交流电机速度控制上,变频器具有良好的调速性能、节能、高效率等诸多优点。在风机、水泵、压缩机等流体机械上应用变频器可取代传统挡板而节省巨额电费;在纺织、化纤、塑胶、化学等工业领域,变频器的自动控制性能可以大大提高产品质量和数量;机械行业中应用变频器是改进传统产业、实现机电一体化的重要手段。     

屋顶绿化的功能及应用现状

介绍屋顶绿化具有城市建筑节能、环境保护等多种功能,通过对国内外屋顶绿化的发展及应用现状概述,着重分析轻型屋顶绿化技术与作用,为推广轻型屋顶绿化提供理论依据,在城市建设与建筑节能领域具有一定的实用价值和理论意义。     

Variation of activation energy of hydrogen absorption of vanadium as a function of aluminum

Hydrogen absorption kinetics of vanadium–aluminum alloys in the temperature range of 624–924 K have been studied. These alloys were prepared by the aluminothermy process and refined by electron beam melting. The data of instantaneous reacted fractions at four different temperatures were obtained using the pressure drop method and these data were linearly fitted to a suitable reaction mechanism function. Three-dimensional diffusion appears to be the intrinsic rate limiting step of the hydrogen absorption. The rate constants were obtained from the slope of the linearly fitted curves. Apparent activation energies were calculated using the Arrhenius equation. The activation energies were increased linearly with aluminum content resulting in a decrease in the hydrogen absorption rate. The variation in standard entropies and enthalpies of vanadium–hydrogen solid solution has been studied as a function of aluminum content.