泥浆泵动力端参数优化及设计外文翻译.doc

毕业设计外文翻译题 目 3NB1300泥浆泵动力端参数优化及结构设计 专 业 机械设计制造及其自动化 班 级 机械设计制造2班 学 生 隆 林 凡 指导教师 胡启国 重庆交通大学2011年重庆交通大学二0一一届毕业设计（论文）外文翻译泥浆泵中密封环的介绍与发展大多数苏联和国外泥浆泵中轴以及轮毂的密封是靠压盖来实现的。排出水在压力作用下进入到密封圈前面的一个洞里面以防止密封管受到外来污染颗粒的影响。然而，这个方法不总是能有效的带出污染颗粒。通常情况下，排除水里面也包含一小部分研磨的颗粒，它也会进入到密封盖前面的洞里面，然后留在了密封压盖上。此外，由于制造误差，在单个的情况下出料侧封盖（与轴以及轮毂的密封相关的密封管被安装在其上）的安装误差会达到2-3毫米。所有这些都导致了非常剧烈的磨损以及密封管的失效。密封管通常运行15-20 h 后就需要替换。密封管运行时，需要持续的检查和调节。在受污染排出水的情况下，在密封管环下，轮毂上沟槽的形成会迅速发生，叶轮也会提前失效。在国外的实践中使用了一个相当复杂的密封，它用的是三个有规则的合成橡胶环，在环之间压力油的作用下使它定位在输料密封盖的轴衬上。然而，根据Gidromekhanizatsiya works的操作数据显示，即使与轴衬相关的轮毂零件有非常高的制造精度和非常小的摆动，没有改变这个环的密封的寿命也只有200-300小时。在1960s，各种各样的组织，特别是Gidromekhanizatsiya works开展了用金属环或者橡胶环来代替压盖。然而，和密封盖相关的叶轮毂的摆动和严重的不匹配度导致了密封的迅速失效。因此，这些工作就停止了。在1980s，由于原材料的缺乏导致输料的密封压盖的生产减少，类似的工作又被重新开展。这项工作的开展和Minenergo计划的新技术有关。根据这个计划，在这个主流20R-11M 泥浆泵对被密封的洞上展开了额外的压力测量。这些测量表明，当把叶轮和圆盘之间的叶轮片卸载的时候，在输料侧密封前面的洞里面的压力大约是工作压力的50%，也就是说，对20R-11M 泥浆泵而言，大约是0.3MPa(30 m H2O)。随着泵的启动，真空压力的增加，相反地在洞里面的压力会减少大约4 m H2O。密封圈工作条件的分析，泥浆泵的设计特点以及Trust谈到制造和迅速引入到实践的可能性表明，平的橡胶项圈密封圈满足所描述的条件。这些密封圈的特点是他们相关的相似性。较早之前，Trust对项圈密封圈开展过工作，但是由于当时相矛盾的运行数据，他们停止了这个工作。为了改善密封圈的设计和优化参数，个人设计部门和实验企业在Trust创立了一个full-sized支架。这个支架能够控制模仿的叶轮的转数，也能够在压力达到0.4Mpa（通过一个按钮，这个压力可以增加大1 Mpa）条件下，提供排出水进入到密封圈前面的洞里面。这个架子也能够测量模仿的叶轮的每分钟转数rpm,在密封装配中因摩擦而消耗的能量，在密封圈前面洞里面的压力，以及密封装配的泄漏。在实验进行中，获得了支架上依赖于能量损失的压力的测量，能量损失是由于在干净的排出水和有研磨物质的受污染的水的传送期间，在压盖和密封装配环之间的摩擦产生的。图表1表明了在20R-11M泥浆泵中密封圈前面洞里的压力关系。分析图表可以得出，对于密封圈前面洞里的工作压力只有0.3MPa和相对干净的排出水传送时，在密封环上的能量损失不会超过在压盖上的能量损失，在5.5-6.0KW之间。在平板橡胶项圈密封环上的摩擦损失的测量证实了公式3的适用性： Nfr=fdhpv/102；在这里f 是在钢筋上的橡胶的摩擦系数，等于0.2；d 是被密封的轴的直径；h 是项圈的尺寸；p 是洞里面的压力；v是在环表面的轴的旋转速度。当受污染的水进入到密封圈前面洞里时，由于装配环的摩擦的持续增加，能量损失会达到10-15KW。在密封圈的参数和设计的完善过程中，在支架上，对厚度是6-16mm，由橡胶薄片组成的平板环进行了测试。在密封环表面的干涉度是3-10%。这些工作的结果是，它证实了对于20R-11M，被密封的叶轮毂直径在320mm的泥浆泵而言，平板环的最优的厚度是10-14mm，干涉度大约是9%（里面环的直径是300mm）。这个环的工作边缘应该向密封洞里面有一个45度的倾斜。在工作压力下，为了不让环向里边翻转，应该通过一个带有锥度的凹槽（可以支撑环）的夹紧盖保护它。图表2展示了这样一种单个环的设计。这种环被安装在输料侧的封盖上，而不是在没有额外加工盖和叶轮的压盖上。平板环一个非常有价值的性质是它能在叶轮毂上自动聚焦。当安装环的时候，它可以在轮毂上伸展，然后自动聚焦就会发生。通过把橡胶环的表面压在泵的轴衬上或者通过夹紧盖就可以提供密封圈的安装结合点。这样做就会在被橡胶环密封的轮毂和盖之间留有2-3mm的间隙。在间隙之间橡胶的弹性可以抵消轮毂2-3mm的摆动。当在轮毂上装配环的时候，环的项圈的组成决定了它的密封性能，密封主要是由轮毂上的压力以及加在面向轮毂的环边缘的水压提供的。有必要注意到，轴的摆动在2-3mm的情况下，根据State Standard GOST 8752-70，标准的橡胶环是无效的，因为它们的聚焦与轴衬有关。实验证明它们不适合泥浆泵。最适合加工和操作的项圈环是一般硬度的抗油气的MBS或者MS橡胶薄片。在Trust的实验企业中，组织了密封圈和环的加工。橡胶环是从车床上的薄片切下来的。在心轴上的薄片被绑紧在车床的卡盘上，使用了一个带有刀片形式切削刃的道具。这洋生产出来的环就具有足够高的质量。密封圈的简化设计使得大量生产和应用到操作中成为可能。在两年内，Trust把超过20R-11M泥浆泵的全部原料的一半变成了单密封环。在16R-9M和500-60泥浆泵上同样得到了应用。根据建设部门的数据，带有一个橡胶环的密封圈的准确的运行时间大概是300h，通过密封圈的泄漏不会超过1公升每分钟。在运行中这样的密封是简单和可靠的。在控制器研究期间，当它被安装在传输站的泥浆泵上时，由于密封洞里面的增加了压力，一个环的密封被认为是不足够可靠和可依赖的。在高压力条件下，为了保证密封，中间带有间隔环的两个平板环的密封设计（如图3所示）就形成了。来源于工业水提供系统的排出水进入到密封环前面的洞里面后，通过中间环的洞进入到密封圈之间的空间里面，然后再以比较小的流动速度排出到外部空间。带有5mm直径洞的节流圆盘被安装在环之间输出管和输入管中，这样就可以区分被密封洞里面的不同压力以及提供可靠的冷却。在启动和真空增加的时候，此外，输入水进入密封圈之间的洞里面都可以阻止空气通过密封装置进入里面的洞，因此缩短了真空建立和泵启动时间。在一个环失效的情况下，泵也可能根据只有一个环的情况照样运行，而不会使泵停止以及分解密封装置。在1985年，Trust指导的对七个20R-11M泥浆泵的两个密封环控制器的实验证明它具有高的可靠性，在没有改变环质量的情况下密封装置的使用时间增加到了1000h左右。目前Trust已经采用了两个环密封的泥浆泵。自从1986年以来，30个机械部件被换成了这样的密封圈。Trust实验企业已经提高了加工一个和两个密封环的技术，也制造出了可以替代的橡胶环。后来密封圈被标准化了。产品的性质容许在2-3年内将整个Trust泥浆泵的原料变成新的密封圈。这个密封圈明书被分发到类似Trust的其他部门。在1983-1984期间，Trust引进一个密封环的经济效果超过30万卢布，引进两个密封环的预期效果是额外增加20万卢布。Sealing of the shaft or hub of the impellerIn the majority of Soviet and foreign mud pumps is accomplished by means of a packing gland.To protect the gland from the entry of soil particles,expulsive water is fed under pressure into the cavity in front of the seal. However,it is not always possible to organize effective expulsion of the soll particles. The expulsive water,as a rule,also contains a small amount of abrasive particles,which enter the cavity in front of the seal and are retained on the packing gland.Furthermore,owing to inaccuracies of manufacture and installation misalignment of the cover of the delivery side in which the gland is installed relative to the impeller hub or shaft with respect to which sealing is accomplished reaches 2-3 mm in individual cases.All this leads to quite intense wear and rapid failure of the gland.The gland is usually re-placed after 15-20 h of operation.Operation of the gland requires constant inspection and regulation.In the case of contaminated expulsive water,rapid formation of grooves on the impeller hub occurs under the rings of the gland and the impeller is replaced prematurely.In foreign practice a rather complex seal with three shaped rubber rings centered on the bushing of the cover of the delivery side with force feed of oil between the rings is used.However,despite the high accuracy of manufacturing the parts and small wobble of the hub relative to the bushing,the service life of this seal without changing the rings is 200-300 h according to the data of operation at the State All-Union Trust for the Planning and Performance of Hydraulicking Works(Gidromekhanizatsiya)of the USSR Ministry of Power and Electrification(Minnergo).In the 1960s at various organizations and,in particular,at Gidromekhanizatsiya works were carried out on replacing the packing gland by rubber rings with metal support rings. However,the large misalignment and wobble of the impeller hub relative to the cover led to very rapid failure of the seal.Therefore,these works were stopped.Similar works were renewed only in the 1980s owing to a reduction in the delivery of gland packing manufactured from scarce raw material.The works were conducted in accordance with the new technology plan of Min6nergo.According to this plan,additional measurements of the pressure in the cavity being sealed on the main 20R-IIM mud pump were taken.These measurements showed that as a consequence of unloading by the impeller blades in the narrow gap between the impeller and disk,the pressure in the chamber in front of the seal of the delivery side is about 50%of the working pressure,i.e.,about 0.3 MPa(30m)for the 20RIIM pump.With starting of the pump and increase of the vacuum a negative pressure of about 4 m occurs,conversely,in this chamber.An analysis of the working conditions of seals,the design characteristics of the mud pumps,and the possibilities of the Trust with respect to manufacture and rapid introduction into practice showed that flat rubber collar sealing rings meet the prescribed conditions. The virtue of these seals is their relative simplicity.Earlier the Trust conducted works on using the collar seals,but in view of the contradictory operating dada they were stopped.To improve the design and parameters of the sealing ring,a full-sized stand was created at the Trust by personnel of the design office and experimental enterprise.The stand made it possible to gradually regulate the number of revolutions of the drum simulating the impeller hub and to feedexpulsivewater into the chamber in front of the seal under a pressure up to 0.4 MPa,by means of a press the pressure could be increased to i MPa.The instruments of the stand made it possible to measure the rpm of the drum,power expended on friction in the sealed assembly,pressure in the chamber in front of the seal,and leaks through the sealing assembly.During the experimental works and measurements on the stand the pressure dependences of the loss of power due to friction in the gland and ring assemblies of the seals during delivery of clean expulsive water and water contaminated with abrasive material were obtained. Figure i shows these pressure dependences in the cavity in front of the seal for the 20R-IIM mud pump(hub diameter 320 rms,speed 500 rpm,size of thecollarI0 mm).An analysis of these graphs shows that for a working pressure in the chamber in front of the seal of about 0.3 MPa and delivery of relatively clean expulsive water the power losses on the sealing ring do not exceed those on the gland and are 5.5-6.0 kW. Measurement of the friction losses in the flat rubber collar sealing rings confirmed the applicability of the formula3: Nfr=fdhpv/102,where f is the coefficient of friction of wet rubber on steel,equal to 0.2; d is the diameter of the shaft being sealed; h is the size of thecollar;p is the pressu rein the chamber; v is the rotating speed of the shaft on the surface of the ring.When contaminated water is fed into the chamber in front of the seal the power losses due to friction in the sealing assemblies substantially increased and reached 10-15kW.During perfection of the design and parameters of the sealing ring on the stand flat rings made of rubber sheet with a thickness from 6 t o 16 mm were tested. The interference of the rings on the surface being sealed was varied from 3 t o 10%.As a result of these works it was established that for the 20R-11M pump with an impeller hub diameter being sealed equal to 320 mm, the optimum thickness of the flat rubber ring is10-14 mm and interference about 9% (inside diameter of the ring 300 mm).The ring should have a working edge with a bevel of about bent toward the sealing chamber. So that the ring does not turn inside out under pressure, it should be secured by a clamping cover with a tapered groove holding the ring. The design of such a single sealing ring is shown in Fig.2. The seal is installed on the cover of the delivery side in place of the gland without additional machining of the cover and impeller.Avaluable property of the flat ring was its self-centering on the impeller hub. When installing the ring it is stretched on the hub and its automatic centering occurs. A fixed joint of the seal is provided by pressing the surface of the rubber to the bushing of the pump by the clamping cover,in doing so a gap of 2-3 mm is left between the hub and cover which is covered by the surface of the rubber ring.The flexibility of the rubber in its gap permits compensating the 2-3mm wobble of the hub.Thecollarof the ring forming when the ring is assembled on the hub determines its self-sealing,which is primarily provided by tension on the hub and then by the water pressure pressing the edge of the ring against the hub.It is necessary to note that in the case of a 2-3 mm wobble of the shaft the standard rubber rings according to State Standard GOST 8752-70are ineffective,since their centering occurs with respect to the bushing.Tests confirmed that they are unsuitable for sealing the mud pump.The most suitable for the manufacture and operation of the collar rings was oil-and-gas resistant rubber sheet MBS or MS of average hardness according to GOST 7338-77. Manufacture of the seal and rings was organized at the experimental enterprise of the Trust. The rubber ring was cut from the sheet on a lathe.The sheet with the mandrel is fastened on the chuck of the lathe,a cutter with a cutting edge in their form of a blade is used.The output of manufacturing the rings is high with their sufficiently good quality.The simplicity of the design of the seal made it possible to organize its mass manufacture and introduction into operation.Within 2 years the Trust converted more than half of its entire stock of 20R-IIM mud pumps to a one-ring seal.Similar seals were developed also for the 16R-9M and 500-60 mud pumps.According to the data of construction administrations,the accured operating time of seals with one rubber ring has averaged about 300 h,leaks through the seal have not exceeded 0.1 liter/min.The seal is reliable and simple in operation. It was established during the pilot studies that the one-ring seal is insufficiently effective and reliable when it is installed on mud pumps of transfer stations owing to the increased pressure in the cavity being sealed.The design of a two-ring seal(Fig.3)was developed for operation of the seal under high-pressure conditions.Two flat rubber rings with a distance ring between them are installed in the seal.The expulsive water is fed from the industrial water supply system both into the cavity in front of the rings and through a hole in the distance ring into the cavity between the rings,the water is discharged at a small flow rate into outside space.On the delivery pipe and discharge pipe from the cavity between the rings are installed throttling disks with 5-mm-diameter holes,which make it possible to divide the total pressure difference in the cavity being sealed approximately in half between the two rubber rings and to provide their reliable cooling4.At the time of starting and increase of the vacuum the delivery of water into the cavity between the rings,furthermore,prevents the breakthrough of air through the