機(jī)械工程及自動(dòng)化專業(yè)外文翻譯--自移式液壓支架

1、機(jī)械工程及自動(dòng)化專業(yè)外文翻譯-自移式液壓支架 外文原文 Self-Advancing Hydraulic Powered Supports Modern longwall mining employs hydraulic powered supports at the face areaThe support not only holds up the roof , pushes the face chain conveyor , and advances itself , but also provides a safe environment for all associated mini

2、ng activitiesTherefore its successful selection and application are the prerequisite for successful longwall miningFurthermore , due to the large number of units required , the capital invested for the powered support usually accounts for more than half of the initial capital for a longwall faceTher

3、efore both from technical and economic points of view , the powered support is a very important piece of equipment in a longwall face The application of modern powered supports can be traced back to the early 1950sSince then , following its adoption in every part of the world , there have been count

4、less models designed and manufactured in various countriesBut unfortunately , there still is no uniform system of classification A simplified classification is used in this sectionsince a powered support consists of four major componentsi. e. , canopy , caving shield , hydraulic legs or props , and

5、base plate , the ways by which they are interrelated are used for classificationIn this respect , two factors are most important : 1 presence or absence of a caving shield - if a caving shield is included , the support is a “ shield type , otherwise , a frame or a chock ; 2 number and type of arrang

6、ing the hydraulic legs - since support capacity is generally proportional to the number of hydraulic legs , it is important to specify the number of hydraulic legs that a support hasFurthermore , the way the hydraulic legs are installed is important ; for example , a vertical installation between th

7、e base and the canopy has the highest efficiency of application whereas an inclined installation between the base and the caving shield has the least efficiency in supporting the roof Based on this concept , there are four types of powered support , that is , the frame , chock , shield , and chock s

8、hield , in order of evolution of their developmentHowever , it must be noted that the trend of development in each type is such that it becomes less distinguishable in terms of application The four types of roof supports can be obtained for either longwall retreating or advancing systems , and they

9、are available in standard , one-web-back , and immediate forward support IFS versions With the standard system , the winning machine takes a cut or a slice , and the armored face conveyor is pushed over by the hydraulic rams that are fixed to the support unitsThe support units then are advanced sequ

10、entially to the conveyorWith the one-web-back system , a support is set back from the conveyor by a device that automatically keeps the leading edge of the support at a fixed distance from the conveyor .This allows easy access through the face and employs the standard method of advancing ; i. e. , p

11、ushing the conveyor first , and then advancing the support With the IFS system , the support unit is advanced to the conveyor immediately after the cutting machine has passed , and the forward canopy of the support unit is long enough to support both the recently and newly exposed roof sectionsAfter

12、 the supports have been advanced , the conveyor is pushed overFRAME The frame support is an extension of the single hydraulic props conventionally used undergroundThus it is the first type developed in modern self-advancing hydraulic powered supports .It involves setting up two hydraulic props or le

13、gs vertically in tandem that are connected at the top by a single or two segmented canopies .The two segmented canopies can be hinge-jointed at any point between the legs or in front of the front leg .The base of the two hydraulic legs may be a circular steel shoe welded at bottom of each leg or a s

14、olid base connecting both legs Fig8.8 Generally , a frame support consists of two or three sets of hydraulic legsThe set moving first is the secondary set , the set moving later is the primary set .There is a double-acting ram installed between each setThe piston of the ram is connected to the secon

15、dary set and the cylinder to the primary setDuring support advance Fig. 8. 9 , the primary set is set against the roof while the secondary set is lowered and pushed forward by the pistonHaving reached the new position , the secondary set is set against the roof while the primary set is lowered and p

16、ulled forward by the cylinderThe distance of each advance ranges from 20 to 36 in. 0.500.91m Fig8.8 Frame support a-primary set b-secondary set A BC Fig8.9 Method of advancing the frame support The frame support is very simple , but more flexible or less stable structurallyThere are considerable unc

17、overed spaces between the two pieces of canopy which allows broken roof rock to fall throughConsequently , the frame support is not suitable for a weak roofFrames have become seldom used because they are less stable and require frequent maintenanceCHOCK In a chock support , the canopy is a solid pie

18、ce and the base may be either a solid piece or two separate parts connected by steel bars at the rear and / or the front endsIn both cases a large open space is left at the center for locating the double-acting hydraulic ram which is used to push and pull the chain conveyor and the chock in a whole

19、unit ,respectively , a distinctive difference from the frame supportThis setup designed for thin seams with two legs in the front and four legs in the rear , separated by a walkwais also used in the shields and chock shields Again , all hydraulic legs are installed vertically between the base and th

20、e canopy Fig. 8. 10The number of legs ranges from three to six , but the four-leg chocks are by far the most popular onesThe six-leg chocks are y Fig. 8.10cFor the six-leg chocks , the canopy is generally hinge-jointed above the walkwayMost chock are also equipped with a gob window hanging at the re

21、ar end of the canopyThe gob window consists of several rectangular steel plates connected horizontally at both ends. ABC Fig8.10 Schematics of various chock support In most chock supports , there are hinge joint connections between the legs and the canopy and between the legs and the baseBut in orde

22、r to increase the longitudinal stability , it is reinforced mostly with a box-shaped steel frame between the base and each legA leg restoring device is installed around each leg at the top of the box-shaped steel frame The chocks are suitable for medium to hard roofWhen the roof overhangs well into

23、the gob and requires induced caving , the chocks can provide access to the gobSHIELD Shields , a new entry in the early seventies , are characterized by the addition of a caving shield at the rear end between the base and the canopyThe caving shields , which in general are inclined , are hinge-joint

24、ed to the canopy and the base making the shield a kinematically stable support , a major advantage over the frames and the chocksIt also completely seals off the gob and prevents rock debris from getting into the face side of the supportThus the shield-supported face is generally clean The hydraulic

25、 legs in the shields are generally inclined to provide more open space for trafficBecause the canopy , caving shield , and base are interconnected , it can well resist the horizontal force without bending the legsThus , unlike the solid constraint in the frame/ chock supports , the pin connections b

26、etween the legs and the canopy ,and between the legs and the base in a shield support make it possible that the angle of inclination of the hydraulic legs varies with the mining heightsSince only the vertical component of hydraulic leg pressure is available for supporting the roof ,the actual loadin

27、g capacity of the shield also varies with the mining heights There are many variations of the shield supportsIn the following ,six items are used to classify the shields , which enables a unified terminology to be developed for all kinds of shieldsThe types of motional traces of the canopy tip , leg

28、 positions and orientation , number of legs , canopy geometry , and other optional designs and devices can be clearly specified by the terminologyTYPES OF MOTIONAL TRACES FOR THE LEADING EDGE OF THE CANOPY. This is the most commonly recognized way of classifying the shieldBased on this criterion , t

29、here are three types , lemniscate , caliper , and ellipse Fig. 8. 11 Fig8.11 Three types of motional traces for leading edge of the shield canopy ALemniscateThis is the most popular typeThe caving shield and the base are jointed by two lemniscate bars which have a total of four hingesAs the hydrauli

30、c legs are raised and lowered , the dimentions of the lemniscate bars are selected such that the leading edge of the canopy moves up and down nearly vertically , thus maintaining a nearly constant unsupported distance between the face-line and the leading edge of the canopy .This is a feature that i

31、s widely considered most desirable for good roof controlThere are clear limits of mining height within which the leading edge of the canopy moves nearly verticallyThese limits are strictly controlled by the dimentional and positional arrangements of the canopy , caving shield , lemniscate bars , and

32、 the baseBeyond these limits , the edges will move rapidly away from the face-line creating a large unsupported area BCaliperIn a caliper shield , the caving shield and the base are connected by a single hinge .When the hydraulic legs are raised , the leading edge of the canopy moves in an arc away

33、from the face , thus increasing the unsupported area This is considered by most users the least desirable feature of the caliper shield But in practice if the seam thickness varies little , the dimentional and positional arrangement of canopy , caving shield , and the base can be so designed that th

34、e distance change of unsupported area will not be significantOn the other hand , when the legs are lowered , it reduces the unsupported area CEllipseIn this type the caving shield and the base are so connected that when the hydraulic legs are moved up and down , the leading edge of the canopy follow

35、s an elliptical traceThis type is seldom usedCHOCK SHIELD The chock shield combines the features of the chocks and the shieldsAs such it possesses the advantages of both If all of the four or six legs are installed between the canopy and the base , it is called a chock shieldThere are regular four o

36、r six-leg chock shields in which all legs are vertical and parallelOthers form V or X shapesSome canopies are a single piece and some are two pieces with a hydraulic ram at the hinge jointThe chock shield has the highest supporting efficiencyThey are suitable for hard roof 中文譯文 自移式液壓支架 液壓支架廣泛應(yīng)用于現(xiàn)代長(zhǎng)臂

37、采煤工作面上。它不但能夠支撐頂板、推進(jìn)工作面刮板輸送機(jī)、自行前移,而且能夠?yàn)榫侣?lián)合采煤作業(yè)提供一個(gè)平安的環(huán)境。因此,正確、合理地選擇液壓支架架型是長(zhǎng)臂工作面采煤成功的前提和關(guān)鍵。此外,井下采煤需要大量的液壓支架,通常對(duì)液壓支架的資金投入占整個(gè)長(zhǎng)臂采煤工作面初期投入的一半還要多。因此,從技術(shù)和經(jīng)濟(jì)的角度來看,液壓支架在長(zhǎng)臂工作面采煤中占據(jù)著非常重要的位置。 現(xiàn)代液壓支架的應(yīng)用可以追溯到上個(gè)世紀(jì)50年代。從那時(shí)開始,支架在世界各個(gè)角落得到了廣泛應(yīng)用,各個(gè)國(guó)家都相繼設(shè)計(jì)和制造了大量的液壓支架。不過始終沒有形成統(tǒng)一的分類體系。 現(xiàn)在通常采用一種簡(jiǎn)化的方法對(duì)液壓支架進(jìn)行分類。由于液壓支架主要有四個(gè)主要

38、局部組成,即頂梁、掩護(hù)梁、液壓立柱(支柱)和底座,因此常根據(jù)它們之間的相互連接方式進(jìn)行分類。鑒于此,對(duì)液壓支架的分類通常采用以下兩種標(biāo)準(zhǔn):根據(jù)掩護(hù)梁的有無分類,如果有掩護(hù)梁那么屬于掩護(hù)式支架,否那么屬于框架式或垛式支架;根據(jù)液壓立柱的數(shù)量和安裝方式分類,支架所能承受的負(fù)載一般與立柱的數(shù)量成比例,因此在介紹液壓支架時(shí)指明其所具有的立柱的數(shù)量是非常有必要的。此外,液壓立柱的安裝方式也是非常重要的。例如,底座和頂梁垂直安裝時(shí),支架具有最高的工作效率,而底座和掩護(hù)梁傾斜安裝時(shí),工作效率比擬低。 基于上述思想,根據(jù)支架的開展歷程,可將其分為四類,即框式支架、垛式支架、掩護(hù)式支架和支撐?掩護(hù)式支架。然而,

39、有必要指出的是,隨著液壓支架的應(yīng)用越來越廣泛,各種類型支架的差異正逐漸縮小。 上述四種支撐頂板的液壓支架可以應(yīng)用于長(zhǎng)臂工作面的回采和推進(jìn),常用的支護(hù)方式主要有標(biāo)準(zhǔn)支護(hù)、滯后支護(hù)和IFS(即時(shí)支護(hù))支護(hù)三種類型。 對(duì)于標(biāo)準(zhǔn)支護(hù)方式,采煤機(jī)通過截齒切割煤層,工作面輸送裝置通過安裝在支架里的液壓千斤頂向新的煤壁推近,然后支架一架一地向輸送機(jī)連續(xù)移近。對(duì)于滯后支護(hù)方式,支架不可能靠近輸送機(jī),因?yàn)橛幸粋€(gè)裝置自動(dòng)地使支架前端與輸送機(jī)保持一定的距離,使得能夠較容易地通過采煤工作面,并且能夠運(yùn)用標(biāo)準(zhǔn)化推進(jìn)方法,即先推移工作面輸送機(jī),再推移液壓支架。對(duì)于IFS(即時(shí)支護(hù))支護(hù)方式,隨著采煤機(jī)向上采煤,液壓支架迅

40、速地向刮板輸送機(jī)推近,支架的前端頂梁的長(zhǎng)度足以支撐原有的和新裸露出的巖石頂板,液壓支架向前推進(jìn)后輸送機(jī)再向前推移?？蚴街Ъ?框式支架是井下用常規(guī)單體液壓支柱的延伸,也是現(xiàn)代自移式液壓支架中最早出現(xiàn)的一種類型。它裝有一前一后兩個(gè)液壓支柱,頂梁通常有整體式和鉸接式兩種。對(duì)于絞接式頂梁,頂梁由兩塊頂梁板在支架頂部連接而成,這兩塊頂梁板可以在兩根立柱之間或前端支柱前面的任意位置處鉸接。支架的底座可以是焊接在兩個(gè)支柱底部的圓形鋼板底靴,也可以是在兩根立柱之間形成的牢固連接。(圖8.8) 圖 8.8 框式液壓支架 通常,框式支架含有兩根或三根液壓立柱。支架移動(dòng)時(shí),首先動(dòng)的是副架,然后是主架。在主架和副架之

41、間裝有一雙作用液壓缸,活塞桿固定在副架上,而缸體固定在主架上。支架推移時(shí)(圖8.9),雙作用液壓缸活塞腔進(jìn)液,主架支撐頂板而副架降柱被活塞桿推動(dòng)前移,到達(dá)新的位置后,副架開始升柱支撐頂板,雙作用液壓缸活塞桿腔進(jìn)液而活塞腔回液,主架降柱被液壓缸缸體向前拉動(dòng)至新的位置,從而完成一次移架操作。液壓支架每次推移的距離在20?36英寸 合0.5?0.91m。 a?前支架 b?后移支架圖8.9 框式支架的移架方式 框式支架結(jié)構(gòu)簡(jiǎn)單、靈活,但是穩(wěn)定性較差。相互連接的兩塊頂梁板之間有相當(dāng)大的未遮蓋空間,這使得破碎的頂板巖石冒落。因而,框式支架對(duì)松軟頂板的適應(yīng)性較差?？蚴街Ъ艿慕Y(jié)構(gòu)不穩(wěn)定并且需要較頻繁的維護(hù)和保

42、養(yǎng),這使得它的應(yīng)用正變得越來越少。垛式支架. 在垛式支架中,頂梁是整體式,底座可能是整體式,也可能是對(duì)分式,由兩個(gè)別離的底座箱在前端或后端通過(彈簧)鋼板或銷軸相連接。支架底座無論是整體式還是對(duì)分式,支架中部都會(huì)留出足夠的空間用來放置雙作用液壓千斤頂,該千斤頂能夠使刮板輸送機(jī)向前推進(jìn)(推溜),還能使垛式支架向前推移(移架)。這也是垛式支架明顯不同于框式支架的地方,這一推移千斤頂裝置也廣泛應(yīng)用于掩護(hù)式支架和支撐?掩護(hù)式支架當(dāng)中。 另外,在垛式支架中,所有的液壓立柱都在底座和頂梁之間垂直安裝(圖8.10)。垛式支架通常采用3?6根立柱,但目前絕大多數(shù)垛式支架裝有4根立柱。六柱垛式支架廣泛應(yīng)用于薄壁煤層的開采,其布置方式為前部2根立柱,后部4根立柱,前后兩局部被一通道隔開。對(duì)六柱垛式支架來說,頂梁通常是在通道上方處鉸接的。大局部垛式支架都在頂梁后端開有通向采空區(qū)的窗口,這些窗口是由很多矩形鋼板在頂梁兩端水平低連接而成的。