外文翻譯--帶傳動系統(tǒng)-10頁[中英word]【中英文文獻譯文】,中英word,中英文文獻譯文,外文,翻譯,傳動系統(tǒng),10,word,中英文,文獻,譯文 中國礦業(yè)大學2007屆本科生畢業(yè)設計 第10頁 翻譯部分 英文原文 BELT CONVEYING SYSTEM Ideally, 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 971 France 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 mm Belt width 1300 mm Belt strength 6590 kN/m Number of cords 57 Vertical lift 990 m Cord diameter 13.1 mm Motor power 10100 kW DRIVING 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 class’E’. 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 10^8 should be specified. 中文翻譯: 帶傳動系統(tǒng) 在理想的狀態(tài)下，若采用此系統(tǒng)對任何礦物運輸時，應能（a）以最大的安全和可靠性，由間隔的生產(chǎn)點形成連續(xù)的礦物流，以保證生產(chǎn)不因運輸?shù)哪承┫拗茥l件而間斷。(b)能操作最高的輸出，(c)使退化降到最低和減小粉塵問題，(d)消除濺射或至少把它收藏起來以及恢復主要礦產(chǎn)地,(e)勞工要求方面提供最佳的經(jīng)濟條件。 一般而言，皮帶傳輸系統(tǒng)符合上述的標準。應用遙感的檢測和控制，連同就業(yè)掩體輸送帶，進一步提高了系統(tǒng)的效率。 這兒有許多限制因素影響帶傳動的使用，這是因為：它需要一個合適的直線運動，它的最大傾斜角度為25度，最大的整體尺寸要少于帶寬尺寸的一半。帶的運輸能力受傾斜角度和皮帶材料的影響，始終要記住的一點是：掠過閑人壓路機，礦物質不斷的干擾皮帶和散布在皮帶上，盡管如此，皮帶還是有很大的運輸潛能，從而可以擴大生產(chǎn)能力。 一個最簡單的皮帶運輸形式包括一對滾筒，其中一個是動力源。并且在它們之間纏繞得有無頭的膠帶。這種簡單的纏繞方式僅限于使用在短距離輸送中，比如用于搬運包裹等。除個別的短距離，頂部的膠帶必須要以固定的間隔的拖棍支撐起來，防止膠帶的下垂。為達到此目的，槽形的拖棍是最理想的。這種拖棍由三個獨立的滾輪組成，有兩個在外部，一個在離它們很近的一端，，并且?guī)乃纳厦娲┻^。對于較低運輸能力的，窄的膠帶，可能使用到兩個拖棍，對于高運輸能力和多塵的工作環(huán)境條件下，可能用到五個或者更多的拖棍。底部或返回帶需要更低的支撐條件，并且很有可能一個平面運行一般使用單一的滾輪，在雙頂?shù)拈g隔距離使用鋼絞線。對于特定的長距離運輸，兩個半凹輥更為合適。 驅動部分通常由電機和齒輪減速箱組成，各個部分通過合適的聯(lián)軸器聯(lián)結，最好預先對齊機器底座，組裝時要求所有的支撐結構支撐到拖棍并，膠帶輪，且要和它對齊。 上面所講的都是典型的皮帶傳輸系統(tǒng)的必要組成元素，如：膠帶，拖棍，滾筒，，驅動部分，和支撐結構，在加上一些其他的部分。選定后進行審查，是開始的最重要的部分，特別是對于帶式傳輸。 運輸機膠帶裝置 運輸傳送帶可以定義為（參閱1）“一些承擔負載運輸?shù)幕暇酆衔?，以及避免機械遭受損壞的橡膠覆蓋層?！?通常的承載部分包括一定數(shù)量的組織物，單一的固體組織物和單一的平行層及等距鋼纜。 在類型方面，對于運輸機膠帶裝置的結構材料可分為耐火和非耐火材料。在某些情況下，前者可能需要通過立法或接受守則的規(guī)定。例如，在英國煤炭開采業(yè)，只有耐火的膠帶用于地下工作。其他大多數(shù)國家也都有類似的規(guī)定。另外還有許多情況下，建議使用耐火材料的膠帶。例如在復雜的選礦廠。在設計任何運輸機膠帶裝置的初期階段，要確定膠帶的類型，這是最重要的，因為兩種不同類型的膠帶將會影響到其他的相關的設備的設計，如果在后期需要作改變，則會有新的問題產(chǎn)生。使用任何特定的皮帶都應該覆蓋到它的采購規(guī)格，由于需要調整皮帶的不同性能來滿足某些摩擦要求，壽命要求以及滿足吸濕的要求等。同時，作為一般性，橡膠帶的沖擊力吸收性要比耐火材料的吸收性好。 這里主要有三種類型結構的的膠帶：（a）層芯結構，（b）整芯編織結構，（c）鋼繩芯結構。 在上述的類型結構中，對于（a）類和（b）類，只有帶芯承擔負載和承受各種工作壓力，即產(chǎn)生在膠帶內部的壓力，很重要的一點是膠帶要具有各種保護能力。在（c）類中，鋼絲繩芯也需要保護。 另外，有專門的皮帶設計系統(tǒng)使用鋼繩牽引膠帶系統(tǒng)，當需要考慮不同的安排結構時，它需要分開來描述。 （1）層芯結構 當討論層芯結構時，經(jīng)常會遇到膠帶的縱向強度和橫向強度，在本小節(jié)，可以用經(jīng)線來代表膠帶的縱向強度，緯線來代表膠帶的橫向強度。 膠帶的橫向彈性是最重要的，這是因為：它能與拖棍的曲線吻合。尤其在使用槽形的拖棍的時候。 傳統(tǒng)的帶芯是由天然的橡膠材料組成的，現(xiàn)在的帶芯由一個或多個合成纖維如尼龍/或滌綸組成，用適當?shù)牟牧习颜麄€融合在一起。這些合成纖維的強度都要比天然纖維（棉花）的強度大，要薄，更具有柔性。，允許使用在更深的槽形拖棍中，較小直徑的膠帶輪上， 并且在重載情況下伸縮量較小。 耐火類型的膠帶的覆蓋層可能是橡膠，聚氯乙烯，氯丁橡膠等。膠帶兩邊的最小覆蓋層應該不少于0.8毫米（0.3英寸），但對于所有的礦物運輸必須增加相關材料的處理。例如，中度磨料如煤，碎石，骨灰等，最小的運輸邊覆蓋層應該2.4毫米，滾筒邊應該是0.8 毫米。更多的磨料物質見附錄5，最小的運輸邊覆蓋層應該是3.2 毫米，滾筒邊是1.6毫米。 盡管各國的標準不一樣，但是皮帶都是根據(jù)它的強度來分的,一個給定的例子就是下面的部分。 （2）整芯編織結構 有許多關于整芯編織結構的說法，但對于后來的整芯編織結構，都是跨編織結構，然后用合適的層鑲以‘堅實’的形式。纖維可能是高強度尼龍紗，棉花，并貫以聚酯的膠帶。標準的耐火形式的材料是聚氯乙烯，但它有一定的局限性，特別是應用在傾斜面的傳輸。為了克服這個缺點，覆蓋層為丁腈橡膠即100%的聚丙烯腈丁二烯，與天然橡膠相比，它具有更大的優(yōu)勢。丁腈橡膠的覆蓋層在運輸面和驅動面都適用，它增加了摩擦系數(shù)和增加了驅動力。對于水分含量高的煤和其他的礦物質，膠帶表面光滑是它的一個重要特征。一個最大的優(yōu)勢是這樣的表層沒有聚氯乙烯的表面光滑。整芯編織結構的膠帶的一個重要特征是它的結構消除了層芯結構的缺點，并且還有良好的運載力抗磨損能力和抵抗礦物油的腐蝕。 現(xiàn)代的的整芯編織結構是使用一把雙刃劍系統(tǒng)而非穿梭系統(tǒng)。為了減少所需時間，它需要改變緯線的部分。同時也為了能整理好織邊。編織過程完成后，帶芯就轉交給整理工藝，即使與聚氯乙烯的復合，另外在表面涂上適當?shù)哪湍ゲ牧希钤趶埩ο聣褐瞥尚汀? 除了滿足英國的的要求外，還需要滿足下述的耐火的規(guī)定和315牛頓到2625牛頓每米膠帶寬的拉伸強度要求： 澳洲 丙二醛系列 250 國際的國際標準組織 R340 加拿大 第 4 起草號碼 M422-M 的南非 SABS 971 法國 NF-M81-651 U. S .A USBM 預定 2G 德國 DIN 22103/4 某一產(chǎn)品包括皮帶的縱向拉伸強度分布在315千牛每米到1000 千牛每米，相關的橫向拉伸強度分布在158千牛每米到350千牛每米?？v向和橫向強度比列不一致，它們的比列相應的從50%降低到30%。高強度的皮帶的縱向強度增加到2625千牛每米，而橫向的強度仍然為350千牛每米。結果，縱橫比很快的降到了11.4%，這是很有必要的的，以便滿足拖棍的的軌跡。 （3）鋼繩芯結構 隨著高強度抗拉皮帶的需求，便產(chǎn)生了相應的皮帶加固要求。即在較高水平的情況下，即使是人造的最高強度的纖維也不能滿足使用要求，結果便用鋼繩芯結構來代替使用，它的縱向強度由鋼絲繩來承擔。這樣的皮帶的制造工藝分為兩個部分，（a）聚酯混合產(chǎn)生一個中心層和兩個覆蓋層，（b）鋼絲繩的組裝，在張力按一個曲線過程進行軋制。 已發(fā)現(xiàn)多種耐火材料，和防靜電的彈性材料 ，并且繩索的垂直的在大于1毫米的情況下會導致彈性材料壓力和張力的失效。如果存在設計缺陷，就會產(chǎn)生這樣的問題。這些問題可以通過使用彈性體硬度在60到68度的的彈性材料來克服。在運輸裝置駕駛中，力矩限制裝置和密切駕駛都可以減少疲勞。 在英國，Sebly綜采的皮帶的具體參數(shù)如下： 運輸裝置長度 1300 毫米 帶厚 28.3 毫米 帶寬 1300 毫米 帶的強度 6590 千牛每米 鋼絲數(shù)量 57 根 垂直舉起距離 990 毫米 繩索直徑 13.1 毫米 電機功率 10100千瓦 驅動輪 必須承認，滑輪或滾筒的設計技改進有并未跟上整個磁頭的技術的發(fā)展。逐漸地，柔性的帶子允許使用在較小的直徑滾筒上，對于給定的帶速，這個滾筒旋轉得更快。皮帶本身也有很快的速度，特別是在焊接處，造成高速滾筒的失效，這都歸因于高疲勞負載。 所有與滾筒應力的相關設計和計算，必須明確循環(huán)應力的比例。樞紐撓度必須低于臨界壓力并且要求焊縫為E等級.輪的疲勞因素至少在1.3至1 之間。疲勞因素比列：最大允許應力幅值與實際應力幅值之比應該大于1.3。 對于無限的壽命—都是所有滾筒設計的目標。應該指出疲勞極限不少于10^8。