支撐掩護(hù)式液壓支架設(shè)計(jì)CAD圖紙+說(shuō)明書(shū)+外文翻譯
支撐掩護(hù)式液壓支架設(shè)計(jì)CAD圖紙+說(shuō)明書(shū)+外文翻譯,支撐,支持,掩護(hù),液壓,支架,設(shè)計(jì),cad,圖紙,說(shuō)明書(shū),仿單,外文,翻譯
本科畢業(yè)設(shè)計(jì)論文(說(shuō)明書(shū)) 第5 頁(yè)
本科生畢業(yè)設(shè)計(jì)
姓 名： 學(xué) 號(hào)：
學(xué) 院： 機(jī)電工程學(xué)院
專(zhuān) 業(yè)： 機(jī)械工程及自動(dòng)化
設(shè)計(jì)題目： 支撐掩護(hù)式液壓支架設(shè)計(jì)
專(zhuān) 題：
指導(dǎo)教師： 職 稱(chēng)： 副教授
二O 年 六 月
畢業(yè)設(shè)計(jì)任務(wù)書(shū)
學(xué)院 機(jī)電工程學(xué)院 專(zhuān)業(yè)年級(jí) 機(jī)械工程及自動(dòng)化 學(xué)生姓名
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畢業(yè)設(shè)計(jì)題目：支撐掩護(hù)式液壓支架設(shè)計(jì)
畢業(yè)設(shè)計(jì)專(zhuān)題題目：
畢業(yè)設(shè)計(jì)主要內(nèi)容和要求：
1．根據(jù)設(shè)計(jì)參數(shù)，確定支架基本類(lèi)型及其結(jié)構(gòu)參數(shù)；
2．完成四連桿機(jī)構(gòu)的參數(shù)設(shè)計(jì)；
3．完成各構(gòu)件結(jié)構(gòu)設(shè)計(jì)、受力分析及其強(qiáng)度校核；
4．完成主要部件、組件及主要零件工作圖的設(shè)計(jì)；
5．編寫(xiě)完成整機(jī)設(shè)計(jì)計(jì)算說(shuō)明書(shū)
院長(zhǎng)簽字： 指導(dǎo)教師簽字：
畢業(yè)設(shè)計(jì)指導(dǎo)教師評(píng)閱書(shū)
指導(dǎo)教師評(píng)語(yǔ)（①基礎(chǔ)理論及基本技能的掌握；②獨(dú)立解決實(shí)際問(wèn)題的能力；③研究?jī)?nèi)容的理論依據(jù)和技術(shù)方法；④取得的主要成果及創(chuàng)新點(diǎn)；⑤工作態(tài)度及工作量；⑥總體評(píng)價(jià)及建議成績(jī)；⑦存在問(wèn)題；⑧是否同意答辯等）：
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評(píng)閱教師評(píng)語(yǔ)（①選題的意義；②基礎(chǔ)理論及基本技能的掌握；③綜合運(yùn)用所學(xué)知識(shí)解決實(shí)際問(wèn)題的能力；④工作量的大??；⑤取得的主要成果及創(chuàng)新點(diǎn)；⑥寫(xiě)作的規(guī)范程度；⑦總體評(píng)價(jià)及建議成績(jī)；⑧存在問(wèn)題；⑨是否同意答辯等）：
成 績(jī)： 評(píng)閱教師簽字：
年 月 日
畢業(yè)設(shè)計(jì)答辯及綜合成績(jī)
答 辯 情 況
提 出 問(wèn) 題
回 答 問(wèn) 題
正 確
基本
正確
有一般性錯(cuò)誤
有原則性錯(cuò)誤
沒(méi)有
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答辯委員會(huì)評(píng)語(yǔ)及建議成績(jī)：
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學(xué)院領(lǐng)導(dǎo)小組綜合評(píng)定成績(jī)：
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翻譯部分
英文原文
SELF-ADVANCING HYDRAULIC POWERED SUPPORTS
Modern longwall mining employs hydraulic powered supports at the face area . The support not only holds up the roof , pushes the face chain conveyor , and advances itself , but also provides a safe environment for all associated mining activities . Therefore its successful selection and application are the prerequisite for successful longwall mining . Furthermore , 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 face . Therefore 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 1950’s . Since then , following its adoption in every part of the world , there have been countless models designed and manufactured in various countries . But unfortunately , there still is no uniform system of classification .
A simplified classification is used in this section . since a powered support consists of four major components(i. e. , canopy , caving shield , hydraulic legs or props , and base plate ) , the ways by which they are interrelated are used for classification . In 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 arranging 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 has . Furthermore , the way the hydraulic legs are installed is important ; for example , a vertical installation between the 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 shield , in order of evolution of their development . However , 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 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 units . The support units then are advanced sequentially to the conveyor . With 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. , pushing 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 sections . After the supports have been advanced , the conveyor is pushed over .
FRAME
The frame support is an extension of the single hydraulic props conventionally used underground . Thus it is the first type developed in modern self-advancing hydraulic powered supports .It involves setting up two hydraulic props or legs 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 solid base connecting both legs (Fig . 8.8) .
Generally , a frame support consists of two or three sets of hydraulic legs . The set moving first is the secondary set , the set moving later is the primary set .There is a double-acting ram installed between each set . The piston of the ram is connected to the secondary set and the cylinder to the primary set . During support advance ( Fig. 8. 9) , the primary set is set against the roof while the secondary set is lowered and pushed forward by the piston . Having reached the new position , the secondary set is set against the roof while the primary set is lowered and pulled forward by the cylinder . The distance of each advance ranges from 20 to 36 in. (0.50~0.91m) .
Fig . 8.8 Frame support
a-primary set b-secondary set
Fig . 8.9 Method of advancing the frame support
The frame support is very simple , but more flexible or less stable structurally . There are considerable uncovered spaces between the two pieces of canopy which allows broken roof rock to fall through . Consequently , the frame support is not suitable for a weak roof . Frames have become seldom used because they are less stable and require frequent maintenance .
CHOCK
In a chock support , the canopy is a solid piece and the base may be either a solid piece or two separate parts connected by steel bars at the rear and / or the front ends . In 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 unit ,respectively , a distinctive difference from the frame support . This 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 the canopy (Fig. 8. 10) . The number of legs ranges from three to six , but the four-leg chocks are by far the most popular ones . The six-leg chocks are y (Fig. 8.10c) . For the six-leg chocks , the canopy is generally hinge-jointed above the walkway . Most chock are also equipped with a gob window hanging at the rear end of the canopy . The gob window consists of several rectangular steel plates connected horizontally at both ends.
A B C
Fig . 8.10 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 base . But in order to increase the longitudinal stability , it is reinforced mostly with a box-shaped steel frame between the base and each leg . A 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 roof . When the roof overhangs well into the gob and requires induced caving , the chocks can provide access to the gob .
SHIELD
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 canopy . The caving shields , which in general are inclined , are hinge-jointed to the canopy and the base making the shield a kinematically stable support , a major advantage over the frames and the chocks . It also completely seals off the gob and prevents rock debris from getting into the face side of the support . Thus the shield-supported face is generally clean .
The hydraulic legs in the shields are generally inclined to provide more open space for traffic . Because the canopy , caving shield , and base are interconnected , it can well resist the horizontal force without bending the legs . Thus , unlike the solid constraint in the frame/ chock supports , the pin connections between 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 heights . Since only the vertical component of hydraulic leg pressure is available for supporting the roof ,the actual loading capacity of the shield also varies with the mining heights .
There are many variations of the shield supports . In the following ,six items are used to classify the shields , which enables a unified terminology to be developed for all kinds of shields . The types of motional traces of the canopy tip , leg positions and orientation , number of legs , canopy geometry , and other optional designs and devices can be clearly specified by the terminology .
TYPES OF MOTIONAL TRACES FOR THE LEADING EDGE OF THE CANOPY.
This is the most commonly recognized way of classifying the shield . Based on this criterion , there are three types , lemniscate , caliper , and ellipse (Fig. 8. 11) .
A . Lemniscate.L B . Caliper.C C . Ellipse.E
Fig . 8.11 Three types of motional traces for leading edge of the shield canopy
A . Lemniscate . This is the most popular type . The caving shield and the base are jointed by two lemniscate bars which have a total of four hinges . As the hydraulic 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 is widely considered most desirable for good roof control . There are clear limits of mining height within which the leading edge of the canopy moves nearly vertically . These limits are strictly controlled by the dimentional and positional arrangements of the canopy , caving shield , lemniscate bars , and the base . Beyond these limits , the edges will move rapidly away from the face-line creating a large unsupported area .
B . Caliper . In 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 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 the distance change of unsupported area will not be significant . On the other hand , when the legs are lowered , it reduces the unsupported area .
C . Ellipse . In 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 follows an elliptical trace . This type is seldom used .
CHOCK SHIELD
The chock shield combines the features of the chocks and the shields . As 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 shield . There are regular four or six-leg chock shields in which all legs are vertical and parallel . Others form V or X shapes . Some canopies are a single piece and some are two pieces with a hydraulic ram at the hinge joint . The chock shield has the highest supporting efficiency . They 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)安全的環(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(lái)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(kāi)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(guò)始終沒(méi)有形成統(tǒng)一的分類(lèi)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(lèi)。由于液壓支架主要有四個(gè)主要部分組成，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(lèi)。鑒于此，對(duì)液壓支架的分類(lèi)通常采用下列兩種標(biāo)準(zhǔn)：
1、 根據(jù)掩護(hù)梁的有無(wú)分類(lèi)，如果有掩護(hù)梁則屬于掩護(hù)式支架，否則屬于框架式或垛式支架；
2、 根據(jù)液壓立柱的數(shù)量和安裝方式分類(lèi)，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)，工作效率比較低。
基于上述思想，根據(jù)支架的發(fā)展歷程，可將其分為四類(lèi)，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，有必要指出的是，隨著液壓支架的應(yīng)用越來(lái)越廣泛，各種類(lèi)型支架的差別正逐漸縮小。
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(lèi)型。
對(duì)于標(biāo)準(zhǔn)支護(hù)方式，采煤機(jī)通過(guò)截齒切割煤層，工作面輸送裝置通過(guò)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(guò)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。
框式支架
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(lèi)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(kāi)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)和保養(yǎng)，這使得它的應(yīng)用正變得越來(lái)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)分離的底座箱在前端或后端通過(guò)（彈簧）鋼板或銷(xiāo)軸相連接。支架底座無(wú)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(lái)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(kāi)采，其布置方式為前部2根立柱，后部4根立柱，前后兩部分被一通道隔開(kāi)。對(duì)六柱垛式支架來(lái)說(shuō)，頂梁通常是在通道上方處鉸接的。大部分垛式支架都在頂梁后端開(kāi)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。
大多數(shù)垛式支架的立柱和頂梁以及立柱和底座之間都是鉸接的，但為了增加支架的縱向穩(wěn)定性，通常在支架底座和各根立柱之間安裝箱形鋼式框架，鋼式框架的上端（立柱四周）裝有立柱復(fù)位裝置。
垛式支架對(duì)硬質(zhì)頂板的適應(yīng)性較強(qiáng)。當(dāng)頂板在采空區(qū)上方被支撐好并且需要進(jìn)行采掘時(shí)，支架可以提供通向采空區(qū)的通道。
圖8.10 垛式支架的各種結(jié)構(gòu)
掩護(hù)式支架
掩護(hù)式支架作為上世紀(jì)70年代初剛出現(xiàn)的產(chǎn)品，其顯著特征是在頂梁末端和底座之間附加有掩護(hù)梁。掩護(hù)梁一般是傾斜的，鉸接在頂梁和底座之間。從運(yùn)動(dòng)學(xué)講，它是穩(wěn)定的，這是掩護(hù)式支架最優(yōu)于框式支架和垛式支架的一點(diǎn)，掩護(hù)梁也完全封閉了采空區(qū)，從而能夠防止破碎頂板巖石掉入支撐工作面。因此，一般來(lái)說(shuō)，掩護(hù)式支架的支撐工作面是較清潔的。
為了給井下運(yùn)輸提供較大的開(kāi)放空間，掩護(hù)式支架里的液壓立柱一般都是傾斜的。由于這種支架的頂梁、掩護(hù)梁和底座間是互相緊密連接的，這使得掩護(hù)式支架能承受水平方向的外加載荷而不使立柱發(fā)生彎曲變形。掩護(hù)式支架里的立柱和頂梁以及立柱和底座之間的銷(xiāo)釘聯(lián)接使得立柱的傾斜角度隨采煤高度的變化而變化，而框式支架和垛式支架中的固定約束則不具有這些優(yōu)點(diǎn)。因?yàn)橹挥幸簤毫⒅軌毫Φ呢Q直分量才能夠支撐頂板，而立柱的傾斜角度是不斷變化的，這使得支架所承受的實(shí)際載荷隨采煤高度的變化而變化。
掩護(hù)式支架有很多種類(lèi)型，通常根據(jù)以下六個(gè)項(xiàng)目對(duì)其進(jìn)行分類(lèi)，即頂梁前端的運(yùn)動(dòng)軌跡、立柱的位置和安裝方向、立柱的數(shù)量、頂梁的幾何形狀、以及其它附屬裝置，這使得應(yīng)用這些統(tǒng)一的術(shù)語(yǔ)對(duì)掩護(hù)式支架進(jìn)行分類(lèi)成為可能。
頂梁前端的運(yùn)動(dòng)軌跡的類(lèi)型
通常，根據(jù)頂梁前端的運(yùn)動(dòng)軌跡來(lái)對(duì)掩護(hù)式支架進(jìn)行分類(lèi)是最常見(jiàn)的一種方法，其軌跡有三種，即雙扭線軌跡、圓形軌跡和橢圓形軌跡。（圖8.11）
圖8.11 頂梁前端的三種運(yùn)動(dòng)軌跡
A.雙扭線軌跡 這是最常見(jiàn)的一種類(lèi)型。掩護(hù)梁和底座之間通過(guò)兩個(gè)搖桿在四處鉸接。如果雙搖桿的尺寸選擇適當(dāng)，則隨著液壓立柱的伸縮，頂梁前端的運(yùn)動(dòng)軌跡將沿豎直方向運(yùn)動(dòng)近似成一條直線。因而能夠在煤壁和頂梁前端之間保持一段近似常數(shù)的無(wú)需支撐的距離。人們普遍認(rèn)為這一特征對(duì)更好地控制頂板是很有好處的。但這種支架也存在明顯的缺點(diǎn)，即頂梁前端內(nèi)的采煤高度只能夠近似的在豎直方向內(nèi)變化，而這一缺點(diǎn)可以通過(guò)頂梁、掩護(hù)架、雙搖桿和底座的相互位置來(lái)嚴(yán)格控制。除此之外，頂梁前端可以從采煤工作面開(kāi)始移動(dòng)以產(chǎn)生一較大的無(wú)需支撐的空間。
B.圓形軌跡 在圓形軌跡的掩護(hù)式支架里，掩護(hù)梁和底座之間通過(guò)單鉸鏈連接。液壓立柱舉升時(shí)，頂梁前端從采煤工作面開(kāi)始以弧形軌跡運(yùn)動(dòng)從而增加無(wú)須支撐空間，大多數(shù)人認(rèn)為這是這類(lèi)掩護(hù)式支架的最大缺點(diǎn)。但是實(shí)際上如果煤層厚度變化很小，掩護(hù)式支架可以設(shè)計(jì)成這種形式，如此一來(lái)，采空區(qū)的高度變化不會(huì)太明顯；另一方面，當(dāng)立柱降落時(shí)，采空區(qū)會(huì)變小。
C、橢圓形軌跡 這種類(lèi)型支架掩護(hù)梁和底座之間的連接能在液壓立柱上下運(yùn)動(dòng)時(shí)，使得頂梁前端沿橢圓軌跡運(yùn)動(dòng)，這種類(lèi)型的支架較少使用。
支撐—掩護(hù)式支架
支撐—掩護(hù)式支架兼有垛式（支撐式）支架和掩護(hù)式支架的特點(diǎn)，同時(shí)兼有這兩種支架的優(yōu)點(diǎn)。
如果在支架的頂梁和底座之間裝有4根或6根立柱，則所有的立柱都是平行并且垂直放置的，而其他的則是排列成V型或X型。支撐—掩護(hù)式支架的頂梁有些是整體式頂梁，還有些是鉸接式頂梁，在鉸接處用液壓千斤頂連接。這類(lèi)支架的支撐效率最高，適用于硬質(zhì)頂板。
本科畢業(yè)設(shè)計(jì)論文(說(shuō)明書(shū)) 第10 頁(yè)
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