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带式输送机液压自动张紧装置设计（含CAD图纸源文件）
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附录 1DEVELOPMENTDEVELOPMENTDEVELOPMENTDEVELOPMENT OFOFOFOF THETHETHETHE CABLECABLECABLECABLE BELTBELTBELTBELT CONVEYORCONVEYORCONVEYORCONVEYORlanlanlanlan MainMainMainMain ThomsonThomsonThomsonThomson BScBScBScBSc (Eng.)(Eng.)(Eng.)(Eng.)ManagingManagingManagingManaging DirectorDirectorDirectorDirectorCableCableCableCable BeltBeltBeltBelt LtdLtdLtdLtdSummarySummarySummarySummaryThe early development of belt Conveying is discussed showing how the Cable belt systemdeveloped from the same requirements. The various design concepts are compared withthose of the troughed belt conveyor highlighting the areas of advantage anddisadvantage.The areas of conveying where the Cable Belt system is most useful and the likelydevelopments are outlined. These and other developments have led to many majorconveyor installations including a 2 flight 52 km system being constructed to the CableBelt design.DevelopmentDevelopmentDevelopmentDevelopment ofofofof thethethethe CableCableCableCable BeltBeltBeltBelt ConveyorConveyorConveyorConveyorThe origin of the belt conveyor is not easy to clearly identify but there are references tosimple forms as early as 1795. However it was not until the dramatic increase in the worldtrading of grain after 1850 that major improvements were made.The first form of conveyor was a flat belt running in a trough which was quickly improvedby the introduction of straight idlers to replace sliding friction by rolling friction. The need toincrease the capacity and centralise the material load led to the appearance at the sametime of both of the most common forms of heavy duty belt conveyors, the troughed beltconveyor and the Cable Belt conveyor.In the late 1860s the use in troughed belt conveyors of straight rollers with conical ordished ends was obsolete until the early 1890s. The introduction in 1865 of inclinedstraight concentrator idlers led to the conveyor in the Thomas Robins Jnr. patent of 1896,which is regarded as the first troughed belt conveyor. Since that date whilst there havebeen many important improvements in the detail of the idler, belt and drive construction,the basic concept of the troughed belt conveyor is the same as outlined in the workcompleted in the early 1900s.The Cable Belt conveyor principle whilst of earlier origin was not developed in a trulysuccessful form until 1952.One of the earliest forms was that developed in 1859 and shown in the sketch fig. 1. Thisconsisted of two parallel endless leather or rubber belts to which were attached atintervals curved meta1 spreaders supporting a canvas trough. There were many othersimilar conveyors but they all suffered from the same basic defect that the carrying beltwas rigidly attached to the driving belts. This led to the disadvantages that the drive beltsdo not stretch alike and that the spreader bars are stressed and eventually break free fromthe drive belts.The Cable Belt system successfully overcame these defects and since its introduction hasgenerally been accepted in the conveyor field for Long distance applications. A substantialproportion of the single flight conveyors over 5 km long that have been installed are nowof the Cable Belt design.The fundamental design differences made in the Cable Belt system were to use a rounddrive belt in the form of a wire rope, and not to attach the carrying belt to the drive belts.The first of these changes was aimed at getting over the difficulty of training to run inparallel a pair of flat belts by substituting positively located round cables running ingrooved pulleys.Early Belt Conveyor Fig 1The second change was the point that allowed the Cable Belt system to operatesuccessfully in contrast to the other earlier attempts. The carrying belt merely rests on thedrive cables, these cables sitting within shoes which are moulded on the be1t surfaces. Itmay seem that depending on friction alone the Cable Belt is liable to have the belt slipbackwards on the drive cables. However as all belt conveyors depend on friction betweenthe belt and the material carried to allow them to operate at all, the only requirement is thatthe friction between the belt and the drive cables should be greater than between the beltand the material. This was achieved by shaping the belt shoes to grip the drive cables.It has been possible using Cable Belt belting with specially formed surfaces to run onslope conveyor systems where the overall grade is 21 and with particular sections of 28,without experiencing slipping of the belt on the drive cables.Whilst the Cable Belt conveyor was developed at a time when the powers available of upto 300 kW were regarded as outstanding the basic concept is still retained even when now,single conveyors of 30000 metre length and 8000 kW power are being built.The terminal units are similar to those in a conventional troughed conveyor except thatthey also serve to separate and rejoin the carrying belt and drive cables. A typicalexample of a head discharge unit is shown in fig. 6.Obviously the terminals other than the drive unit are more complex than in a conventionaltroughed conveyor and take up more space particularly in the case of the tensioningarrangements. This is not true of the drive as for a comparable power rating it is compactand has the advantage that it can be located remote from the Cable Belt conveyor beltline.Head Discharge Unit Fig 6As the modulus of elasticity of the drive cables is kept relatively low in order to allow theuse of very low starting torques and each drive cable is tensioned, the tension systemdoes require substantial take-up space and is more complex as is illustrated in fig. 7.Typical Tensioning Arrangement Fig 7The concepts behind the design of the Cable Belt conveyor are very similar to aconventional conveyor in that there is conveyor friction and the vertical alignment is aseries of catenaries but of course the factors used vary considerably because of thedifferent characteristics.The conveyor friction losses are considerably reduced principally because of thesignificantly lower number and weight of moving parts in a comparable system.This reduction is normally in the order of 30%. In addition the friction losses due to theworking of belt and material as they pass over the idlers are significantly less. it has beendetermined empirically that there is in the order of a 10% reduction in the friction losses.The establishing of the facts, even on a comparative basis, with regard to conveyor frictionhas proved difficult as all the data is empirical and the various design standards can showmarkedly different results. In addition conveyor friction will vary with temperature, age andstandards of installation and maintenance. However in a recent major installation it hasbeen possible to compare the friction values, at least on a design basis and as can beseen below these bear out the differences.ConventionalCable BeltNumber of Rotating Parts10076Weight of Moving Parts10064Friction Losses10067In determining the vertical alignment of the Cable Belt system whilst the formulae andcalculation are the same, great care must be exercised as it is not possible to allow lift offin catenaries to occur.Early Cable Belt Belting Fig 2Intermediate Cable Belt Belting Fig 3Modern Cable Belt Belting Fig 4The Cable Belt is best defined as a belt conveyor with a laterally rigid but longitudinallyflexible carrying belt which is supported at or near its edges on two parallel endless loomsof drive cable, these cables in turn being supported at intervals by grooved pul1eys. Theintegral reduction gear and drive unit drives both drive cab1es and incorporates adifferential to equalise tensions in the cables. In addition each of the drive cable circuits isseparately tensioned to allow for the differential stretch of these during operation.The unique feature of the Cable Belt system is the belt. Originally this was a fabricreinforced rubber belt which had moulded into it spring steel straps at 450 mm intervals.These straps protruded beyond the edges of the bell as illustrated in fig. 2, and hadmechanically attached to them a metal shoe with rubber Lining where it gripped the drivecable. This was superseded by a one piece moulded construction shown in fig. 3 wheresmaller cross section straps at intervals of 100 mm were moulded entirely within the beltand the shoes to grip the drive cables were continuous mouldings along the edge of thebelt.Typical 4 Pulley Line Stand Fig 5Recently a further change was made, illustrated in fig. 4 whereby the shoes which grip thedrive cable on the material carrying run have been moved inwards. This increases thestability of the belt when subjected to overloading and in addition allows the use of smallercross section straps.Angle Station Fig 8It is normal that on a typical long centre conveyor the eventual replacement of the belt isnot for reasons of abrasion of the surface or mechanical damage, but due to the variousageing processes that affect rubber compounds such as heat, sunlight, and ozone. As aresult it has been necessary to develop special synthetic rubber compounds that areinherently resistant to ageing.The specification of the drive cables whilst similar superficially to a normal wire rope arespecially made to a Cable Belt specification with design criteria laid down for individualwire size, fatigue life and internal lubrication. They are of galvanised construction, LangsLay with either a fibre or wire rope core. Currently they are used in sizes up to 60 mmdiameter and breaking loads of 260 tonnes. As this is the tension reinforcing member ofthe Cable Belt system great attention is paid to reducing the number of splices and drivecables of up to 100 tonnes weight for each section have been used.Along the line of the conveyor it is supported at intervals of between 5 and 10 metres bygrooved pulleys approximately 300 mm in diameter. Previously these pulleys were of ahardened steel construction but the current design is for a pulley with a replacementrubber lined tread. These pulleys are mounted in pairs on articulated arms which allow theconveyor to self align and equalise the loads on each pulley as can be seen in fig. 5.Whilst this condition is normally avoided in all conveyor design, it is essential, to preventderailment of the drive cables, to design catenaries correctly and conservatively.As is well known the normal catenary formulae are approximations which allow a factor ofsafety against lift off. In designing the Cable Belt system the same formulae and factorsare used, but effectively the protection against lift off is increased by determining worstpossible loading conditions and limiting the starting torques. This situation is helped in thatthe conveyor friction is such and modulus of the drive cables is selected to ensure thatthere is virtually no additional breakaway torque required even to start a long flat overlandCable Belt system.The major difference in designing a Cable Belt conveyor lies in the separation of thecarrying belt and the drive cables. Whilst good design practice requires that they shouldbe kept together, the ability to separate them does give considerable flexibility in designand allows the introduction of concepts unknown in the conventional belt conveyor. Themost widely used of these is in the many circumstances where a straight line route or oneincorporating curves is not feasible, and the unit known as an angle station is employed.As can be seen from fig. 9 this allows any angle up to 320 to be accommodated and stillretain the feature of a single drive but incorporate two separate carrying belt circuits. Thisfeature is used in about 30% of the Cable Belt installations. The other concept that iswidely used is as mentioned earlier, the ability to place the drive unit remote from the beltline. This feature, which is unique, allows the drive unit and its associated electricalequipment to be located in a position with easy access for maintenance but away from thedust and dirt associated with a conveyor discharge or return belt line. This flexibility alsoallows the drive unit to be placed at any point in the conveyor, including if necessary onthe material carrying run of the drive cables.The other part of the Cable Belt design that is unique is the tensioning system and there isno doubt that this is more complex and takes greater space than would be required in atroughed belt conveyor. There are several reasons for this but the principal reason is thenecessity to provide equipment to separately tension each drive cable and the carryingbelt. Whilst the tension in the carrying belt is nominal it is still necessary to cater for thedrive cable tension movement, particularly in long flat conveyors which, of necessity, aretensioned at or near the drive unit. In such conveyors the tension movement of the drivecables is substantial during the start sequence. Before the whole conveyor is moving theeffect is that it is necessary to store in the carrying belt tension system a length of beltequivalent to the elastic stretch of the drive cables. This of course is released when theconveyor stops. In a typical 15000 metre long conveyor this stretch can be up to 80metres.The main reason for taking up a greater space than a troughed belt conveyor is thenecessity to cater for both the permanent stretch and the relatively high elastic stretch ofthe drive cables. The permanent stretch of about 1% which occurs in the first few hundredhours of running could be eliminated during manufacture but it conveniently provides thenecessary space for splicing of the cable as well as generating extra cable which can beused when resplicing is necessary The choice of the modulus that governs the elasticstretch is a compromise between minimising the stretch to reduce the space requirementsand having sufficient stretch to ensure very low breakaway torques.As can be seen from the foregoing information the Cable Belt system while fulfilling thesame role in many ways is quite different from the troughed belt conveyor. As mostconveyors are of short length and low horsepower there is no doubt that the troughed beltconveyor is the correct solution for many conveyor applications. However in those areasof long lengths or high lifts the Cable Belt system often shows decisive advantages and inthose cases where its unique design concepts can be used it may be the only choice.To define the precise applications which a Cable Belt system is suitable for is difficult, asnearly one third of the systems installed are in applications in which they were not themost competitive solution. In each case they were chosen for one of the unusual featuresthat the system offers. As a general rule the Cable Belt in its current form is not technicallysuitable for short centre conveyors mainly due to the size of the terminals. In addition tothe cost of the terminal equipment the main cost component of any belt conveyor, the belt,in the Cable Belt system has a constant cost irrespective of the power requirements. This1oads the capital cost on low power conveyors but reduces it on high power conveyors incomparison with a troughed belt conveyor.In summary the current competitive situation of the Cable Belt system appears to be :-In slope conveyors of less than 750 kW or level conveyors of less than 3000 metrelength the Cable Be1t is not the most competitive solution. Above these parametersthe Cable Belt becomes increasingly competitive in capital cost.In leve1 conveyors where the power due to friction losses is a substantial part of thetotal, the operating costs of the Cable Belt system are becoming increasinglyattractive. In other cases there does not appear to be any significant differences.There is one significant development of the Cable Belt system which is currentlyundergoing field trials. When generally available in the next few years it should, for thesame capital cost, show a significant reduction in operating costs. This involves theproduction of a drive cable where the individual wire reinforcing strands are separatelymoulded within an elastomer giving a round steel and elastomer drive cable. Initial resultshave been most encouraging with a three fold increase in the fatigue life as against aconventional steel wire rope.Recent developments in the Cable Belt system show that it can effectively compete withrail transport over distances which until now have not been regarded as suitable forconveyor systems. As an example there is currently being constructed in WesternAustralia for Worsley Alumina Pty. Ltd. a two flight, 52000 metre Cable Belt conveyorsystemTo be operated by Worsley Alumina Pty Ltd., and located near Perth., W. Australia, thisinstallation incorporates two Cable Belt conveyors in tandem and is an overland systemwhich transports crushed bauxite from the mine to a refinery.At the intersection of the two conveyors, the material is turned through 50 (to the left) bymeans of chutes and rock boxes and fed to the second stage Cable Belt conveyor.Both the conveyors are angle drive conveyors with their drive and tension units located atthe transfer/discharge ends of each conveyor. To minimise spares holdings, theconveyors have been standardised with almost complete interchangeability ofcomponents.Length:Length:Length:Length:31000m31000m31000m31000m21000m21000m21000m21000mDifferenceDifferenceDifferenceDifference inininin elevation:elevation:elevation:elevation: (Fall)(Fall)(Fall)(Fall)72m72m72m72m14m14m14m14mMaterial:Material:Material:Material:BauxiteBauxiteBauxiteBauxiteDensity:Density:Density:Density: (Specific(Specific(Specific(Specific Gravity)Gravity)Gravity)Gravity)1520152015201520 kb/mkb/mkb/mkb/m RatedRatedRatedRated capacity:capacity:capacity:capacity:2040204020402040 m.t.p.h.m.t.p.h.m.t.p.h.m.t.p.h.AnnualAnnualAnnualAnnual tonnage:tonnage:tonnage:tonnage:9,069,069,069,06 x x x x 101010106 6 6 6BeltBeltBeltBelt width:width:width:width:900900900900 mmmmmmmmOperatingOperatingOperatingOperating speed:speed:speed:speed:6,356,356,356,35 m/secm/secm/secm/secDriveDriveDriveDrive cable:cable:cable:cable:57575757 mmmmmmmm dia.dia.dia.dia.LinestandLinestandLinestandLinestand pitch:pitch:pitch:pitch:4,754,754,754,75 mmmmPower:Power:Power:Power:5300530053005300 kWkWkWkW3600360036003600 kWkWkWkWIn conclusion it would appear that the Cable Belt system has the capability of furtherdevelopment which should permit, the expansion of belt conveying into even longereconomic lengths than those currently under construction.The Author wishes to acknowledge the assistance given by WorsleyAlumna Pty. Ltd.,and the Cable Belt companies in the preparation of this paper.References:References:References:References:1.Belt Conveying and Belt Elevators - Hetzel and AlbrightJohn Wiley & sons2.The Fu11ing Resistance of Belt Conveyors - H.P. Lachman附录 2钢绞线带式输送机的发展托马森 （英）总经理钢绞线带式输送机有限公司摘要： 早期带式输送机的发展被认为是与钢绞线带式系统相同的需求而发展起来的， 其本质就是各种设计原理与槽形带式输送机突出部分的优缺点进行比较， 而这一部分的发展恰恰表明，在传送系统中最可能也最有用的发展，就是对其外形轮廓的改进，这些使得在一些大型钢绞线设计建造中，考虑安装长达 52 千米的螺纹槽系统（2 个） 。钢绞线带式输送机发展在 1795 年时，最初的带式输送机不便于操作，而且仅涉及一些简单的外形，直到 1850年后，随着世界范围内的谷物货量大量增加，促使传送带技术有了较大的改进。第一种形式的传送机是在一个槽形及其内运行的水平传送带， 其工作原理是引进导轮系统用滚动摩擦来替代滑动摩擦， 以便减少传送中的摩擦损失。 随着需求的不断增长以及大量的集中装卸货物的需要， 使得在这一时期最普遍的货物带式输送机。 草型带式输送机以及钢绞线带式输送机都获得较大发展。在 1860 年后期， 大量使用带有锥形或蝶形滚动导轮的槽形带式传送机， 直到 1890 年才过时被淘汰。1865 年倾向于将直线集中器或跨轮引入到传送机发明设计中，这使得托马斯.罗宾在 1896 年获得该产品的专利权，被认为是历史上第一台槽形带式输送机。从那时起，许多重大改进在跨轮传送带和操作结构等一些细节方面。但在 1900 年早期，所有的槽形带式输送机都具有相同的外型，在外型上并没有改进。同最初的机器相比，钢绞线带式输送机真正意义上获得较大成功的发展是在 1952 年，而在 1859 年，最早期的设计形式之一，如图一所示。图中包括两条平行无较差的皮带制成胶质的传送带， 被按一定距离贴附在弯曲的金属表面上，使得这种帆布式槽形带式输送机正常运行，也有许多相似的输送带类型，但它们承受从动带被刚性的贴附在主动带上，这些基本相同的缺点这也导致许多缺点例如： 主动带并不能完全与草图设计吻合，或者是润滑剂承受重压，最终从主动带脱落等。图一钢绞线传动带系统成功地克服了这些缺点， 并且这一技术被大范围的用在传送机长距离的应用中。现在一种单臂长 54 米的螺纹槽系统已经被考虑在设计中。钢绞线传送带系统设计原理的基本不同在于采用一种圆形的金属线形式的主动带， 而不是传统的将从动带附着在主动带上。 第一步改变致力于克服通过三角皮带轮式运行中的水平传送带被钢绞线替代所产生的困难。 第二步改变是着眼于钢绞线传送带系统本身可以进行操作，这与早期设计的目标恰恰相反。主动带主要依附于从动带上，这些钢绞线被放置在传送带表面压制好的滑轨上， 它或许是紧依靠摩擦力是钢绞线传送带在主动带上向后滑行， 然而同所有带式输送机依靠摩擦力在传送带上运载货物相比， 钢绞线时仅需满足在传送带和主动钢绞线间的摩擦力应大于在传送带和货物之间的摩擦力， 这应使得传送带制动器仅仅牢固在主动钢绞线上。钢绞线带式输送机也可用于特殊形式的表面，在斜面传送机整体系统中等级是 21，一些特殊形式的可达 28，在传动钢绞线上不存在打滑脱落的现象。钢绞线带式输送机伴随着发动机进一步发展而发展的，当发动机功率达到 300 千瓦时（被认为是最杰出的设计） ；由此而开始建造长达 3000 米，功率 8000 千瓦的传送机。钢绞线传送给与槽形传送机除在工作方式上不同，其它一些末端的输出单元是相似的，也联合从动带与主动带，一个典型的例子是上部的卸货装置，如图六所示：图六明显地， 除传动单元终端设备之外的其他设备要比传统的槽形带式输送机复杂得多， 并且占据更多的空间，特别是在考虑张力等作用下更是如此，这并不是真正意义上的传动装置， 而是仅对其功率额定值进行比较，当它满负载时，需能控制运处的钢绞线传送机正常工作。传动钢绞线的张力模数保持在相对低的水平是为了获得较低的初始扭矩， 并且当每个传动钢绞线拉紧时，张力系统需要占据较大的空间，并且更复杂，如图七所示：图七后期的钢绞线带式输送机设计理念与传统的非常相似的， 在传送机中也存在摩擦， 并且垂直找平装置是一系列的悬垂链，但如果应用于不同的领域，应考虑各种不同的性能，且考虑降低传送机的摩擦损失，可以通过减少动件的数量和重量，这种损失正常值为 30%，而额定的摩擦损失取决于工作中的传送带与货物之间的损失，而采用滑轮装置可大大减少这种损失，理论上测量能答曰降低 10%的损失，做一基本比较，这一事实很令人吃惊。关于摩擦损失已经证实往往很难克服，并且所有的观测数据和设计标准，显示出不同的测试结果，另外摩擦损失取决于各种因素，此外，输送机摩擦将随着安装和维护的温度，寿命和标准变化。在一些大型设备安装中，比较部分摩擦值至少在一个基本设计中能看到如下不同之处：传统型钢绞线型回转件数量10076可动件数量10064摩擦损失10067钢绞线带式输送机的垂直找平系统与槽形机设计和计算原理是相同的， 必须进行反复测试确保悬垂链脱落这样的事情不会发生。钢绞线传送带被定义为横向坚固纵向轻柔的带式输送机， 而从动带依附于两条平行主动带的侧翼或边缘部分。 减速齿轮箱和活动单元来对主动钢绞线进行控制，以及对不同钢绞线拉伸张力的差别超界调整。此外，每一根主动钢绞线在工作中允许承受不同的拉伸力。钢绞线传送带独特的特点是体现在传送带上， 最初是一种加强橡胶传送带， 被铸造在以450 毫米为间隔的弹簧搭接片上，这些搭接片伸出起搭架轮之外，如图二所示，并且机械的附着在金属制动器上，橡胶传送带与主动钢绞线相连，这可以被一种铸造结构所代替，如图三所示， 一些较小的交叉搭接片以间隔 100 毫米的距离完全铸造在传动带和制动器上， 以便使主动钢绞线仅仅固定在传动带边缘。最近，已经对此作进一步改进，如图四，当货物在其上移动时，制动器仅仅控制主动钢绞线，这也使得当发生超重时，增加传送带的稳定性。 另外可以采用更好的交叉搭接片。图二图三图四长期集中使用传送机，最终得更换传送带，这是很正常的，或者是由于表面的摩擦损失造成的,或许是机械性的损坏，但主要
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