外文翻译--带传动系统-10页[中英word].doc
外文翻译--带传动系统-10页[中英word]【中英文文献译文】
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中国矿业大学2007届本科生毕业设计 第10页翻译部分英文原文BELT CONVEYING SYSTEMIdeally, the system adopted for the transport of any mineral should: (a) provide continuity of mineral clearance from the point of production with maximum safety and reliability, to ensure that production is not interrupted by transport restrictions, (b) be capable of handling the peak outputs, (c) minimize degradation and dust problem , (d) eliminate spillage or at least incorporate means for its collection and reintroduction to the main mineral stream, (e) provide optimum economy in labour requirement .In general terms, belt conveying systems satisfy the above criteria. The application of remote monitoring and control. Together with the employment of bunker conveyors , further enhance the efficiency of the system.There are limiting factors affecting the use of belt conveyors in that generally a reasonably straight run is necessary, the maximum angle of inclination is normally 25 degrees (1 in 4) and the maximum lump size is to be less than about half the width of the belt. The carrying capacity is influenced by the angle of repose of the material transported, keeping in mind that passing over the idler rollers, the material is continuously disturbed and spread out on the belt. Notwithstanding the above the belt conveyor has a tremendous and expanding mineral transport potential.In its simplest form a belt conveyor consists of a pair of drums, one of which is powered, and between which is stretched an endless band. This elementary arrangement has limited use for other than short distance application such as the carrying of packages, etc. . For other than short distance the top band must be supported by regularly spaced idlers to prevent sagging. Troughing idlers are ideal for this purpose, a set of which normally consists of three separate rollers, the two outer and shorter being inclined upwards to trough the belt. For low capacity, narrow belts, two idlers may be used and for high capacity duty, five or more may be employed. The button or return belt requires a lower level of support and generally may run in a flat plane, a usual arrangement being to use single rollers, at double the spacing distance used with the top strand. With exceptionally long conveyors, two roll semi-troughed return rollers may be justified. The drive arrangements normally consist of an electric motor and speed reduction gear-box, connected to each other by suitable couplings and preferably pre-aligned on a machined bed plate, the assembly being associated with an all embracing supporting structure to support and align the idlers, pulleys and drive.The above comprise the essential elements of a typical belt conveyor; belt, idlers, pulleys, drive and structure, to which are added other important items, a selection of which will be examined, starting with probably the most important;the conveyor belt.CONVEYOR BELTING A conveyor belt that may be defined (ref. 1), as “ a number of load carrying members bonded together with polymeric compounds (making up the carcase) and protected from mechanical damage by elastomeric covers. The load carrying members usually consist of either a number of plier of woven fabric, a single solid woven fabric carcase, or a single layer of parallel, equidistant steel cables”. At the onset it must be stated that conveyor belting of any construction, may be classified as Fire Resistant or Non-fire Resistant. In certain underground situations, the former may be required by Legislation or by accepted Codes of Practice. For example, in the U.K. coal mining industry, only Approved fire resisting belting may be used underground. Most other developed countries have similar requirements. In addition there are many situations where the use of fire resistant belting is recommended, for example, in complex mineral benefication plants. It is most important that in the early stages of design of any conveyor system, the type of belt be determined, as differing characteristics of the two types may influence the design of other associated equipment, and problems may be introduced if a change is required at some later date. The use to which any particular belt is to be subjected should be covered in the purchase specification, since the various properties of a belt may need modification to accommodate the sometimes conflicting demands of coefficient of friction, ageing characteristics, moisture absorption, etc. .Also as a generality, a belt of rubber construction has a greater ability to absorb impact than one of fire resistant construction.There are three main constructional forms of belting : (a) ply construction, (b) solid woven construction, (c) steel cord construction. In the above constructions, (a) and (b), only the carcase provides the strength to carry the load and withstand the various operational stresses that are developed in the belt. Since the carcase is the most expensive element in the belt, it is important that the specification incorporates adequate means of protecting this most important element. In the(c), the load carrying steel cords requires like protection. Additionally, there is the specialised design of belt with the Cable belt system which will be separately described when that arrangement is considered.(1)Ply Belt Construction When discussing ply belting, the terms warp and weft often occur, for the purpose of this sub-section it may be taken that : warp refers to the longitudinal strength of the belt, and weft refers to the lateral strength of belt.The lateral flexibility of the belt is always of importance in order that it may conform to the idler curve, this being particularly so when deep troughing idlers are to be used.The traditional belt carcase consisted of layers of woven natural fabric, this now consists of one or more plies of synthetic fibres such as nylon and /or terylene, the whole being vulcanised or fused together with the appropriate cover material. Such synthetic fibres are stronger than natural fibres (cotton), are thinner, more flexible, allowing deeper troughing in the idlers, allow the use of smaller diameter pulleys and have a shorter elongation under high working tensions.The cover may be rubber in the case of non-fire resisting belts and PVC, Neoprene, etc. ,in the case of fire resisting types. The minimum cover on both side of any belt should be not less than 0.8 mm (0.3 in) but for the transport of almost all mineral must be increase having regard to the material handled. For example ,with moderately abrasive materials such as coal, rubble, ashes, etc. ,the minimum carrying side cover should be 2.4 mm with 0.8 mm on the pulley side. With the more abrasive minerals, see Appendix 5, the minimum carrying side over should be 3.2 mm with 1.6mm on the pulley side.Although national standards may vary, a belt type may be classified having regard to its strength, an example being given in the next sub-section.(2)Solid Woven Belt Much of that said about ply belting applies to the solid woven form , but in the later, the fibres from which the belt carcase is constructed are inter-woven, then impregnated to give a solid form, and to which appropriate covers are applied. The fibers may be of high tenacity nylon warp, cotton pile and blended weft, with certain qualities of belting employ a polyester warp. In the standard fire resisting form the cover may be PVC, but this has certain limitations, particularly in respect of conveying up inclines. To overcome this problem the cover may be of nitrile rubber, i.e. 100% butadiene acrylonitrile polymer, which offers the advantages of natural rubber. Such nitrile rubber covers are applied to both the carrying and the driving faces of the belt with consequently improved frictional characteristics which minimize load slip and afford increase driving traction. A smooth pressed finish permits more efficient belt cleaning an essential feature in view of the higher moisture content of coal and indeed many other minerals. A further advantage is that such covers do not polish in service as dose PVC . An important feature of solid woven belt is that the construction eliminates ply separation and gives excellent resistance to edge wear, further, it is rot proof and resistant to mineral oils.A modern loom to manufacture solid woven belting employs a rapier weft insertion system rather than a shuttle, to eliminate the down time require to change weft bobbins, and also to give a good selvedge finish. The weaving process finished, the carcase is transferred to the finishing process which entails impregnation with liquid PVC compound, giving an additional, appropriate wear resistant surface coating, finally being press cured under tension.In addition to satisfying U.K. requirements such belts conform to the following fire resistant specifications and are readily available in tensile strengths from 315 to 2625 kn/m of belt width: Australia MDA-Series 250 international ISO R340 Canada 4th Draft No. M422-M South Africa SABS 971France NF-M81-651 U. S .A USBM Schedule 2G Germany DIN 22103/4 A particular product range includes belts ranging in tensile warp (longitudinal ) strength ranging from 315 to 1000 kn/m, with associated warp ( lateral ) strength from 158 to 350 kN/m, the weft to warp ratio varies progressively from 50 down to 35%. Higher strength belts then increase to a tensile strength to 2625 kN/m, the weft strength remaining constant at 350 kN/m. Consequently , the weft/warp ratio drops rapidlly down to 11.4%, this being necessary to allow ready tracking in the troughing idlers. (3) Steel Cord belt Construction The ever increasing demand for higher tensile strength belting created a corresponding demand for stronger belt reinforcements, which at higher level cannot be satisfied by the use of even the highest strength man-made fibers, resulting in the use of the steel cord belt in which the warp strength is provided by steel cables. Such belt is manufactured in a two part process, (a) the mixing of ploy chloroprene to produce a centre matrix and the two cover layers , and (b) the assembly of cords , matrix and covers in a rolling process with the cords under tension, followed by a curing process. It has been found that a combination of hard (80 degrees ) fire resistant, anti-static (FRAS) elastomers and cords displaced vertically at a distance greater than 1 mm leads to the failure of the elastomer by compression and tension. Like problems may occur if there are defects in the design concept. Such problem may be overcome by the use of elastomers with a hardness in the 60 to 68 degree range-this being a stringent requirement when additives to drive ensure fire retardency are employed. Fatigue may be minimized by close attention to drive and return drum diameters and by the use of torque limitation devices in the conveyor drive. The details of the belt employed at the Sebly Mining Complex, England, are : Conveyor length 14.93 km Belt thickness 28.3 mmBelt width 1300 mm Belt strength 6590 kN/mNumber of cords 57 Vertical lift 990 m Cord diameter 13.1 mm Motor power 10100 kWDRIVING DRUMS It must be conceded that improvements in drum or pulley design has not kept pace with the overall drive-head developments. Increasingly flexible belts allow the use of smaller diameter pulleys which then rotate faster for a given belt speed. Belts themselves also run faster, resulting in yet higher rotational speed-pulleys then fail, particularly at welded connections, due to their high fatigue loading. In all stress calculations associated with drum design, explicit allowances must be made for stress ratios due to their cyclic loading. Hub deflections must be below the critical stress level and all welds should be classE. Drums should have a Fatigue Reserve Factor(FRF) of at least 1.3 to 1. the FRF being the ratio: Maximum Allowable Amplitude Stress/Actual Amplitude Stress, which should be 1.3. For infinite life-which should be objective of all drums design, a fatigue limit of not less than 108 should be specified.中文翻译:带传动系统在理想的状态下，若采用此系统对任何矿物运输时，应能（a）以最大的安全和可靠性，由间隔的生产点形成连续的矿物流，以保证生产不因运输的某些限制条件而间断。(b)能操作最高的输出，(c)使退化降到最低和减小粉尘问题，(d)消除溅射或至少把它收藏起来以及恢复主要矿产地,(e)劳工要求方面提供最佳的经济条件。一般而言，皮带传输系统符合上述的标准。应用遥感的检测和控制，连同就业掩体输送带，进一步提高了系统的效率。 这儿有许多限制因素影响带传动的使用，这是因为：它需要一个合适的直线运动，它的最大倾斜角度为25度，最大的整体尺寸要少于带宽尺寸的一半。带的运输能力受倾斜角度和皮带材料的影响，始终要记住的一点是：掠过闲人压路机，矿物质不断的干扰皮带和散布在皮带上，尽管如此，皮带还是有很大的运输潜能，从而可以扩大生产能力。一个最简单的皮带运输形式包括一对滚筒，其中一个是动力源。并且在它们之间缠绕得有无头的胶带。这种简单的缠绕方式仅限于使用在短距离输送中，比如用于搬运包裹等。除个别的短距离，顶部的胶带必须要以固定的间隔的拖棍支撑起来，防止胶带的下垂。为达到此目的，槽形的拖棍是最理想的。这种拖棍由三个独立的滚轮组成，有两个在外部，一个在离它们很近的一端，并且带从它的上面穿过。对于较低运输能力的，窄的胶带，可能使用到两个拖棍，对于高运输能力和多尘的工作环境条件下，可能用到五个或者更多的拖棍。底部或返回带需要更低的支撑条件，并且很有可能一个平面运行一般使用单一的滚轮，在双顶的间隔距离使用钢绞线。对于特定的长距离运输，两个半凹辊更为合适。 驱动部分通常由电机和齿轮减速箱组成，各个部分通过合适的联轴器联结，最好预先对齐机器底座，组装时要求所有的支撑结构支撑到拖棍并，胶带轮，且要和它对齐。 上面所讲的都是典型的皮带传输系统的必要组成元素，如：胶带，拖棍，滚筒，驱动部分，和支撑结构，在加上一些其他的部分。选定后进行审查，是开始的最重要的部分，特别是对于带式传输。运输机胶带装置 运输传送带可以定义为（参阅1）“一些承担负载运输的化合聚合物，以及避免机械遭受损坏的橡胶覆盖层。” 通常的承载部分包括一定数量的组织物，单一的固体组织物和单一的平行层及等距钢缆。 在类型方面，对于运输机胶带装置的结构材料可分为耐火和非耐火材料。在某些情况下，前者可能需要通过立法或接受守则的规定。例如，在英国煤炭开采业，只有耐火的胶带用于地下工作。其他大多数国家也都有类似的规定。另外还有许多情况下，建议使用耐火材料的胶带。例如在复杂的选矿厂。在设计任何运输机胶带装置的初期阶段，要确定胶带的类型，这是最重要的，因为两种不同类型的胶带将会影响到其他的相关的设备的设计，如果在后期需要作改变，则会有新的问题产生。使用任何特定的皮带都应该覆盖到它的采购规格，由于需要调整皮带的不同性能来满足某些摩擦要求，寿命要求以及满足吸湿的要求等。同时，作为一般性，橡胶带的冲击力吸收性要比耐火材料的吸收性好。 这里主要有三种类型结构的的胶带：（a）层芯结构，（b）整芯编织结构，（c）钢绳芯结构。 在上述的类型结构中，对于（a）类和（b）类，只有带芯承担负载和承受各种工作压力，即产生在胶带内部的压力，很重要的一点是胶带要具有各种保护能力。在（c）类中，钢丝绳芯也需要保护。 另外，有专门的皮带设计系统使用钢绳牵引胶带系统，当需要考虑不同的安排结构时，它需要分开来描述。（1）层芯结构当讨论层芯结构时，经常会遇到胶带的纵向强度和横向强度，在本小节，可以用经线来代表胶带的纵向强度，纬线来代表胶带的横向强度。胶带的横向弹性是最重要的，这是因为：它能与拖棍的曲线吻合。尤其在使用槽形的拖棍的时候。传统的带芯是由天然的橡胶材料组成的，现在的带芯由一个或多个合成纤维如尼龙/或涤纶组成，用适当的材料把整个融合在一起。这些合成纤维的强度都要比天然纤维（棉花）的强度大，要薄，更具有柔性。，允许使用在更深的槽形拖棍中，较小直径的胶带轮上， 并且在重载情况下伸缩量较小。耐火类型的胶带的覆盖层可能是橡胶，聚氯乙烯，氯丁橡胶等。胶带两边的最小覆盖层应该不少于0.8毫米（0.3英寸），但对于所有的矿物运输必须增加相关材料的处理。例如，中度磨料如煤，碎石，骨灰等，最小的运输边覆盖层应该2.4毫
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