外文翻譯---液壓支架自動化成功的途徑

1、<p><b>　　附錄A譯文</b></p><p>　　液壓支架自動化成功的途徑</p><p><b>　　1. 摘要</b></p><p>　　第一架液壓頂板支護(hù)在20世紀(jì)50年代內(nèi)安裝在了地下，并且自那以后隨著機(jī)械工程的發(fā)展已經(jīng)從許多方面完善了支架。然而，頂板支護(hù)機(jī)械設(shè)計(jì)、水力工程學(xué)和電子學(xué)這三個主要

2、領(lǐng)域的進(jìn)步最終在支架運(yùn)用35年后實(shí)現(xiàn)了自動化，并且已經(jīng)普及當(dāng)前。</p><p>　　頂板支護(hù)自動化的歷史介入了高技術(shù)工程學(xué)的連續(xù)綜合化。將來有進(jìn)一步的可能性是它們結(jié)合在一起為最終實(shí)現(xiàn)無人操作的新面貌提供一個可能的思想。</p><p><b>　　2. 介紹</b></p><p>　　大約35年前，一個變化發(fā)生在了煤炭行業(yè)，事后看來，它為煤

3、炭產(chǎn)業(yè)從高勞動力密集場所演變成今天鋪平了道路。這個變化便是液壓頂板支護(hù)的引入。</p><p>　　第一代支架，采用簡單的液壓閥控制，一開始就突飛猛進(jìn)的發(fā)展，為改善工作場所的安全性和提高生產(chǎn)力作出了貢獻(xiàn)。相對支柱和氣壓計(jì)的用途，支護(hù)頂板的活動“實(shí)際上被自動化”，以后為獲得更大自由度的挑戰(zhàn)就要落在頂板支護(hù)設(shè)計(jì)師的肩膀上了。</p><p>　　結(jié)果，許多改進(jìn)發(fā)生在了結(jié)構(gòu)和環(huán)境機(jī)械工程以及使用

4、水為基礎(chǔ)的流體可靠操作的液壓系統(tǒng)的發(fā)展領(lǐng)域。這被改進(jìn)的工程學(xué)，加上采礦工程師們總結(jié)出不同類型巖石層適合什么樣的支架安裝型式的經(jīng)驗(yàn)，知識在不斷豐富，機(jī)械結(jié)構(gòu)的強(qiáng)度也在提高。</p><p>　　早在1967年，英國煤礦就試驗(yàn)使用電子控制支架，并且第一套遙控長壁采煤系統(tǒng)被用于地下。不幸地是，無論在頂板支護(hù)還是今天的電子技術(shù)，不只是效率就能提供必需的成功。</p><p>　　掩護(hù)式支架的發(fā)展與

5、改善后的閥材料和流體的可及性以及“芯片”電子技術(shù)相符了。那是隨著掩護(hù)式支架為電液壓系統(tǒng)的應(yīng)用提供了理想的環(huán)境后，促使自動化成功的發(fā)展因素的結(jié)合。</p><p>　　今天，這些技術(shù)的進(jìn)步，與微處理器的引入一起，為煤炭行業(yè)提供了極端可靠，靈活和高效率的系統(tǒng)。</p><p>　　自動化的頂板支護(hù)不再是設(shè)計(jì)師的夢想，而是真實(shí)的，每天運(yùn)作的現(xiàn)實(shí)。</p><p>　　現(xiàn)代

6、頂板支護(hù)的前身是木制的坑柱。所以，在20世紀(jì)50年代中期，第一架支架被設(shè)計(jì)出來時，這些僅僅是已知的技術(shù)的延伸。</p><p>　　在第一架垛式支架中， 帶有英寸長鏜孔的液壓油缸垂直放于箱體內(nèi)作為基底，頂梁是一對工字梁。固定在底部的液壓缸起到為刮板輸送機(jī)提供傳動力和驅(qū)動支架上升的作用。</p><p>　　今天的用戶能很容易知道垛式支架的很多缺陷，這些缺陷有的還沒設(shè)計(jì)出來，有的可能被忽略掉

7、了。盡管如此，相對坑柱和氣壓計(jì)的老方法，第一代支架向前邁了很大的一步，在安全和生產(chǎn)率方面做了真正的貢獻(xiàn)。</p><p>　　在第一次發(fā)展后，進(jìn)步就更快了。一個主要的需求是為地面操作人員提供更安全的運(yùn)輸方式。這就需要根據(jù)它們的支架頂梁和底版增加前柱或換成四柱。這會大大改善頂梁的控制性能。</p><p>　　到20世紀(jì)60年代早期，這些相互聯(lián)系的支架裝載容量達(dá)到了180噸，被直接用于改進(jìn)制

8、造和液壓技術(shù)，即便在地下使用仍被限制在1.5米的煤層厚度。</p><p>　　隨著對獲取更高煤層的需求，長壁采煤也遍及了全球。這也進(jìn)一步導(dǎo)致對支架的裝載輸送容積的要求更高了。緊接著在1968年引進(jìn)了底版牢固的垛式支架。第二代支架能滿足720噸的容量，而且可以在3米厚的煤層中工作。 </p><p>　　掩護(hù)式支架是在20世紀(jì)70年代涌現(xiàn)的，最早的兩柱式掩護(hù)梁設(shè)計(jì)在德國被廣泛使用，并被引進(jìn)

9、到美國和南非。掩護(hù)式支架的效率低，但能承受很高的載荷。</p><p>　　雙紐線設(shè)計(jì)是在20世紀(jì)70年代后期引進(jìn)的。掩護(hù)式支架要求在設(shè)計(jì)原理上從根本改變。機(jī)械連接除抵抗垂直方向變形外，還有巖層側(cè)面的力。它提供了更有效可靠的支架，它的粗壯使它成功地應(yīng)用在煤層中的長壁系統(tǒng)中，這在以前是不可能的。例如，在新南威爾士和澳大利亞那極端困難的條件下以及在英國更易破裂的頂板下。</p><p>　　現(xiàn)

10、代掩護(hù)式支架的效率為自動化的成功應(yīng)用提供了合適的環(huán)境。</p><p>　　在美國更側(cè)重于結(jié)構(gòu)的掩護(hù)式支架是兩柱設(shè)計(jì)，這種設(shè)計(jì)是許多自動化發(fā)展的主要平臺，也是目前可使用的。</p><p>　　這種結(jié)構(gòu)正被引入英國和澳大利亞，而且在未來很長一段時間內(nèi)將處于頂梁支護(hù)自動化發(fā)展的最前線。</p><p>　　3. 20世紀(jì)80年代后的液壓支架</p>&l

11、t;p>　　頂梁支護(hù)系統(tǒng)使用大量的液體裝滿整個系統(tǒng)，以彌補(bǔ)泄露量和其他流動損耗。此經(jīng)濟(jì)因素和其他如火災(zāi)和運(yùn)輸大量液體方面的問題帶來了以水為基礎(chǔ)的液壓支護(hù)系統(tǒng)。</p><p>　　以水為基礎(chǔ)的液壓技術(shù)的應(yīng)用已經(jīng)在工程學(xué)上占據(jù)了一個領(lǐng)域，頂梁支護(hù)生產(chǎn)者們真正利用了這項(xiàng)技術(shù)，甚至現(xiàn)在，有很少的工業(yè)液壓技術(shù)設(shè)施生產(chǎn)者的文件夾里包含可與流體配套使用的產(chǎn)品。</p><p>　　最早期的頂板支

12、護(hù)系統(tǒng)使用的是根本不復(fù)雜的密封和閥門技術(shù)。簡單的開關(guān)閥和帶有一系列包裝的皮帶密封是最好的，可在比7Mpa高的壓力下工作。</p><p>　　工程師們很快意識到為了發(fā)揮集中力的作用，需要特殊的閥齒輪確保立柱有足夠的支撐度，簡化操作方法。之后為了保障工作環(huán)境和設(shè)備的安全性，方便工作人員操作，單向閥、排出閥和選擇活門便應(yīng)運(yùn)而生了。一直以來，制造商使用軟硬不同的各種各樣的材料，開發(fā)了不同的閥門座形式閥門密封技術(shù)在慢慢地

13、得到改善。</p><p>　　隨著生產(chǎn)廠家逐漸使用各種硬度的橡膠和橡膠織品綜合的橡膠材料時，支柱和密封技術(shù)就迅速地發(fā)生了變化。</p><p>　　堅(jiān)持不懈的工程師們夢想成真是最終的制動楔軟管的發(fā)展，它們很快幾乎普遍替代了螺紋聯(lián)接。</p><p>　　流體技術(shù)也是制造問題的一個領(lǐng)域。開始時有乳化油和水。但從來沒有想過的是，混合使用的水可能有許多潛在的災(zāi)難性影響。

14、堅(jiān)硬太大、太小、金屬鹽和細(xì)菌破壞了水或油形成的乳化液。造成分離物， 熔渣、過濾器堵塞。最終使設(shè)備出現(xiàn)了嚴(yán)重的問題。</p><p>　　例外地，在乳化液里含有高水平可變的流體百分比導(dǎo)致了分離物和熔渣，低強(qiáng)度在閥門齒輪和圓筒之內(nèi)導(dǎo)致了嚴(yán)重腐蝕。</p><p>　　流體逐漸改善,英國煤礦對Spec.18和Spec.19水的公認(rèn)讓流體的發(fā)展明確達(dá)到了混合水的硬度。</p><

15、;p>　　微量的垃圾制造的流體污染在地下依然是一個問題。相對而言，最近又有了新的突破。過濾器堵塞，旁路被接受曾經(jīng)是實(shí)際情形。結(jié)果是旁通閥，在泵上的極端磨損，卸荷閥等。</p><p>　　閥門齒輪在20世紀(jì)70年代初期朝自動化的方向發(fā)展。伴隨著一系列的壓力閥和銷閥的引入，它們構(gòu)成了應(yīng)用于3頂板支護(hù)的液壓邏輯機(jī)構(gòu)的基本元件。然后它試圖由操作員從簡單的控制閥啟蒙運(yùn)動著手創(chuàng)造程序化的操作。單體支護(hù)，一些包括支柱和

16、前部的某些相當(dāng)復(fù)雜體因被控制。技術(shù)延伸到一批或邊坡控制。此設(shè)計(jì)中，一定數(shù)量的支護(hù)由液壓邏輯從他們中的任意一個傳遞出的啟蒙信號程序化。</p><p>　　現(xiàn)代電液壓機(jī)構(gòu)的第一個Gullick先行者在每一個邊緣的確使用了，一個主動制動器，帶動電子和電磁閥和3個從動制動器。在過去，因?yàn)殡娮蛹夹g(shù)太復(fù)雜，液壓邏輯元件更受歡迎。事實(shí)上液壓學(xué)是比較復(fù)雜的，閥門齒輪通常在必要的時候被掩藏在橡皮絕緣管下，特別是如果液壓機(jī)構(gòu)中的流

17、體不足被維護(hù)了，對維護(hù)鉗工來說是個惡夢。</p><p>　　液壓和電液壓自動化的這些早期的失敗導(dǎo)致20世紀(jì)70年代初期自動化陷入了困境，而且更簡單的系統(tǒng)被恢復(fù)了。然而發(fā)展仍在繼續(xù)。最重要的是，掩護(hù)式支架開始涌現(xiàn)。</p><p>　　4. 80年代的頂板支護(hù)電子學(xué)</p><p>　　早在1964年，人們就意識到電力對自動化起著舉足輕重的作用。</p>

18、<p>　　在英國煤礦螺栓企圖被用來生產(chǎn)一個完全自動化的面孔包括在ROLF項(xiàng)目之下的創(chuàng)始機(jī)械。</p><p>　　整個系統(tǒng)癱瘓了，不是他們付出的努力少，而是由于那時的設(shè)備和頂板支護(hù)太過簡單而不適宜。然而，ROLF這個項(xiàng)目設(shè)想某天自動化能實(shí)現(xiàn)。</p><p>　　短暫的平息直到20世紀(jì)70年代晚期，英國煤礦沉重的責(zé)任項(xiàng)目再次喚醒了自動化的想法。</p><

19、;p>　　Gullich Dobson判斷一個液壓初始系統(tǒng)意味著成功的希望，雖然已經(jīng)意識到早期用于ROLF的不可改變的“硬邏輯”的缺陷。</p><p>　　所以，在控制箱內(nèi)使用微處理器控制的決定和在出口處使用計(jì)算機(jī)是明智的選擇。但并不是在相對想對新鮮的微處理機(jī)技術(shù)中沒有指定的風(fēng)險。</p><p>　　自動連續(xù)軟件放在末端計(jì)算機(jī)中，命令被傳達(dá)到智慧OFUs，激活電磁閥，依順序駕駛操

20、作頂板支護(hù)。</p><p>　　三個Gullick電液壓系統(tǒng)工作面在20世紀(jì)70年代晚期投入使用，發(fā)展在系統(tǒng)中進(jìn)入了高潮，不再使用液壓邊緣邏輯控制液壓支架和刮板輸送機(jī)，支柱也得以延伸。</p><p>　　另一發(fā)展是采煤工作面對準(zhǔn)線，刮板輸送機(jī)的平直度和網(wǎng)深度由微處理器基于在支架上的電路板控制，使用末端計(jì)算機(jī)連接到表面。</p><p>　　兩種安裝形式都被生產(chǎn)，

21、盡管遭受著各種各樣的問題，包括水的流入碰撞位置傳感器，它們證實(shí)了采煤工作面對準(zhǔn)線和表面?zhèn)鬏數(shù)脑怼?lt;/p><p>　　5. 現(xiàn)代頂板支護(hù)控制系統(tǒng)</p><p>　　自動化早期的失敗到當(dāng)前證實(shí)了最終目標(biāo)總有一天會達(dá)到，以下是得出的結(jié)論。</p><p>　　1．掩護(hù)式支架為自動化的應(yīng)用提供了正確的環(huán)境。</p><p>　　2．閥齒輪需要被

22、設(shè)計(jì)成在高壓下是可靠的，容許有污染，能承受快的流動速度。</p><p>　　3．支柱和和滑枕能承受高載荷，快速操作，并且適合重流量的條件下。</p><p>　　4．微處理器是一種敏感的電學(xué)元件，要求高速度，多操作，可暴露內(nèi)在安全系統(tǒng)的極限，使用電磁閥和更簡單的硬連線邏輯電子。</p><p>　　Gullick開始通過尋址結(jié)論2發(fā)展新一代的方案。它有遮護(hù)板，微處

23、理器，新一代的立柱和滑枕正在被開發(fā)。</p><p>　　閥門齒輪能在大于30Mpa的壓力下工作，低電流是關(guān)鍵成份，在1984年Gullick引入了動力化的閥門。這10到20毫安導(dǎo)閥能相當(dāng)愉快地運(yùn)作在35 Mpa，并且仍然提供流程。與大約消耗120 MA的電磁閥相比，由于平滑的操作和可利用的高應(yīng)力，可靠性更好。</p><p>　　動力閥和以前的螺線管系統(tǒng)相比,允許內(nèi)在安全電源的多操作局限

24、被克服，允許至少五倍閥門的數(shù)量同時被管理。</p><p>　　因而電牽引系統(tǒng)產(chǎn)生了，動力化的閥門被結(jié)合了對實(shí)現(xiàn)最新的CMOS低功率芯片和技術(shù)的一個微處理器控制系統(tǒng)。這導(dǎo)致系統(tǒng)內(nèi)部每一個支架配備以O(shè)FU、閥門組裝和相同簡單的液壓系統(tǒng)。終端計(jì)算機(jī)作為媒介控制自動化過程。</p><p>　　1984年電牽引系統(tǒng)的第一次安裝在英國煤礦Sherwood礦區(qū)，是一次巨大的成功，可行的終端計(jì)算機(jī)控制

25、被實(shí)現(xiàn)，包括短礦柱和前柱的控制。</p><p>　　1985年此系統(tǒng)開始使用，安裝在澳大利亞和美國。盡管如此，環(huán)境問題困擾著美國的試驗(yàn)，澳大利亞的設(shè)備運(yùn)行得非常好，仍每天在Baal Bone使用著。</p><p>　　環(huán)境問題主要是與濕度大和用軟管滅火相關(guān)。一旦被認(rèn)可，便恢復(fù)到正常位置，直到1988年設(shè)施才成功地安裝。West Cliff在1988年翻新改進(jìn)電牽引系統(tǒng)。</p&g

26、t;<p>　　同時， 電牽引系統(tǒng)頂板支護(hù)的快速的速度對密封設(shè)計(jì)領(lǐng)域的發(fā)展發(fā)號施令。高速經(jīng)常意味著熱化，這可能與半合成或合成流體潤滑液的減少同時進(jìn)行，然后可能產(chǎn)生更多的問題，這樣，新一代的密封設(shè)計(jì)產(chǎn)生了。</p><p>　　高壓產(chǎn)生的地方，密封在傳統(tǒng)的橡膠和橡膠織物間交換著。使用了塑料，現(xiàn)在成為耐用的準(zhǔn)則。</p><p>　　1988年，對Gullick來講，向下按的電鈕

27、成批成順序的操作成為標(biāo)準(zhǔn)是顯而易見的，機(jī)器初始者-關(guān)于ROLF的試驗(yàn)仍被需要。</p><p>　　以前大多數(shù)的實(shí)驗(yàn)使用了計(jì)時器系統(tǒng)。脈沖或數(shù)據(jù)不斷地把剪切軌跡輸入到頂板支護(hù)控制系統(tǒng)中。然而，交界面對大量剪切形式的不可靠度和需求在這次試驗(yàn)中呈現(xiàn)出極大的難度。</p><p>　　Gullick決定紅色為執(zhí)行的路徑，開發(fā)了一種具有以下主要屬性的系統(tǒng)：</p><p>

28、　　1．可以拍打灰塵的寬大的，耀眼的紅色發(fā)光體。</p><p>　　2．編碼在紅色傳輸中保證系統(tǒng)不被其他燈光或照明設(shè)備激活。</p><p>　　3．是一個軟件，對信號的偶然丟失可容許和可編程序。</p><p>　　這個系統(tǒng)是成功的，可通過增加生產(chǎn)和減少勞動力立即給消費(fèi)者帶來利益。</p><p>　　由于Gullick 電牽引系統(tǒng)始終是

29、基于生產(chǎn)量的微處理機(jī)，很容易擴(kuò)展系統(tǒng)的靈活性，機(jī)器和人都可以操作，迎合了大多數(shù)消費(fèi)者的需求。看到早期軟件程序的成功潛力的顧客率先開發(fā)該系統(tǒng)，與Gullick軟件組一起提供以下設(shè)施：</p><p><b>　　1．再試</b></p><p>　　2．反繼電器氣壓計(jì)銷軸破損</p><p><b>　　3．工作面末端序列</b&

30、gt;</p><p>　　4．模式外的工作面選擇</p><p>　　5．雙重機(jī)器序列 </p><p>　　今天的電牽引系統(tǒng)是多功能的，可靠的。機(jī)器啟蒙經(jīng)常指定，最近設(shè)備的翻新安裝在West Cliff，例如，導(dǎo)致在機(jī)器啟蒙控制之下工作面生產(chǎn)記錄噸數(shù)。</p><p>　　當(dāng)前系統(tǒng)仍然使用動力化的閥門和其他基本原理，直接返回到1984年

31、在Sherwood的系統(tǒng)，間接地返回到從70年代晚期最早的微處理器系統(tǒng)。</p><p>　　與主要流量開關(guān)一起，小型化了的動力化的閥門被改進(jìn)了并且形成整體系列的閥齒輪。</p><p>　　電子設(shè)備使用更新的芯片，但仍然包含基本的電路連接板和通過15年的輪距記錄加強(qiáng)微處理器界面用途的軟件。</p><p>　　與控制一樣，監(jiān)測立柱的壓力可以提供，界面對準(zhǔn)線是可利用

32、的(雖然由于滑枕系統(tǒng)效率的改善，不是當(dāng)前普遍的)， 由此，完整的電路最先開始在1978年。</p><p>　　如此，最先在60年代晚期設(shè)想出ROLF的那些工程師的夢想和客觀事實(shí)-自動化，機(jī)器啟蒙， 無人管理都在今天得以實(shí)現(xiàn)。但是未來是什么樣子呢？</p><p>　　6. 未來的頂板支護(hù)自動化</p><p>　　當(dāng)前有幾個發(fā)展準(zhǔn)備把液壓支架自動化帶入新的一代，與

33、其他系統(tǒng)在長壁的結(jié)合將實(shí)現(xiàn)普遍。</p><p>　　隨著軟件和硬件的開發(fā)使系統(tǒng)更具智能，頂板支護(hù)系統(tǒng)自身將變得更加自動化，從而能在無關(guān)緊要的情況下和固有的采煤問題上（如頂板漏洞）獨(dú)立應(yīng)付。例如，系統(tǒng)為控制4根支柱的支架使用傾斜傳感器提供平衡的機(jī)蓋限制支架后部滲透到洞里，已經(jīng)在發(fā)展使用了。</p><p>　　程序的發(fā)展和新的傳感器技術(shù)將使頂板支護(hù)系統(tǒng)繼續(xù)被提高以完善它們本身， 專家系統(tǒng)編

34、程，系統(tǒng)從它自己的錯誤中吸收經(jīng)驗(yàn)，在垂直方向。</p><p>　　然而，頂板支護(hù)系統(tǒng)在長壁中不再是唯一的靈巧的系統(tǒng)。 采煤機(jī)、刮板輸送機(jī)和互換機(jī)控制以及環(huán)境監(jiān)測設(shè)備全部有固有的智力。</p><p>　　當(dāng)命令發(fā)出時，將來的自動化將把這些各種各樣的智能系統(tǒng)連接在一起，以便信息可以在系統(tǒng)之間傳輸，有利于全部。</p><p>　　世界各地各種各樣的煤炭操作員現(xiàn)在正在

35、接受局部綜合化方法，共同的宗旨是改進(jìn)設(shè)備的可靠性和生產(chǎn)率，允許維護(hù)任務(wù)時更容易管理。</p><p>　　在中期它似乎可能把分開的子系統(tǒng)結(jié)合在一起成為一個單元。現(xiàn)代微處理器和編程技術(shù)已經(jīng)在向這方面發(fā)展，那是技術(shù)上可行的，而且僅僅是時間問題，不是條件問題。</p><p>　　當(dāng)綜合流程被充分開發(fā)，每個界面的子系統(tǒng)由專家系統(tǒng)編程時，也許最后有機(jī)會安裝第一個完全無人操作的局面。 直到那時，看到

36、任何人為水平的主要減少是困難的。</p><p><b>　　7.結(jié)論</b></p><p>　　通往頂板支護(hù)自動化的道路已經(jīng)踩踏，成功的結(jié)果最終會到來。</p><p>　　許多因素作出了貢獻(xiàn)，它的確歸功于許多的工程師，設(shè)計(jì)師和用戶，他們在35年前的夢想終于實(shí)現(xiàn)了。</p><p>　　因?yàn)槊禾抗I(yè)跨入一個能量競爭性

37、的新時代，自動化的角色將變得越來越重要，作為通往更高生產(chǎn)力的主要手段。當(dāng)前，對頂板支護(hù)似乎仍然要有很長的路要走。</p><p><b>　　附錄B外文文獻(xiàn)</b></p><p>　　The path to Successful Roof Support Automation</p><p>　　1 ABSTRACT</p>&

38、lt;p>　　The first hydraulic roof supports were installed underground in 1950s and ever since that engineering developments have improved the supports in many different ways.However,advances in three main areas,the roof

39、 support mechanical design,hydraulic engineering and electronics have ultimately led to the point where ,35 years after that installation,automation has been achieved and is now commonplace.</p><p>　　The his

40、tory of roof support automation has involved the continual integration of high technology engineering.There are further possibilities for the future which combine to give some idea of the likelihood of there ultimately b

41、eing a completely manless face.</p><p>　　2 INTRODUCTION</p><p>　　Around 35 years ago,a development took place within the mining industry that,with hindsight,paved the way for this industry to ch

42、ange from being a highly labour intensive one,to the industry of today.This development was the introduction of the hydraulic roof support.</p><p>　　The first generation support,with its simplistic hydraulic

43、 tap controls,was a quantum leap in its time,contributing to improved safety of the workplace and improved productivity.Relative to the use of props and bars,the activity of supporting the roof had actually been “automat

44、ed”,and thereafter the challenge for greater degrees of automation was laid firmly at the feet of the roof support designers.</p><p>　　Consequently,many improvements were made in the fields of structural and

45、 environmental mechanical engineering and the development of hydraulic systems which would operate reliably using water-based fluids.This improved engineering ,coupled with the development knowledge of the mining enginee

46、rs of the effects of and load patterns induced from different types of strata,led to the development of competent mechanical structures.</p><p>　　Early attempts to use electronics to control these supports w

47、ere made within British Coal and the first ROLE system (Remote Operated Longwall Face ) was installed in 1967.Unfortunately there was simply not the efficientcy in either the roof support or the electronics technology of

48、 the day to provide the required success.</p><p>　　The development of the shield support coincided with the availabilities of improved valve materials and fluids and also of “chip” electronic technology.It w

49、as the marriage of these developments that led to automation success,with the shield support providing the ideal environment for the application of electro-hydraulics.</p><p>　　Today,enhancements of these te

50、chnologies,along with the introduction of the microprocessor,provides the industry with extremely reliable,flexible and efficient systems.</p><p>　　The automated roof supports are no longer a designer dream

51、but are a true ,every-day working reality.</p><p>　　The ancessor of the modern roof support is the wooden pitprop.Therefore,when,in the mid 1950s,the first “roof supports”were designed,these were merely exte

52、nsions of the known technology.</p><p>　　In the first chock supports,hydraulic jacks of 2inch bore were held vertical in a simple box frame forming the base and the canopy was a pair of simple I-beam girders

53、.A hydraulics jack mounted in the base provided for conveyor push and roof support advance.</p><p>　　Clearly the users of today can easily understand the multitude of shortcomings-some of which still had not

54、 been designed out and some,it may be argued,which were inadvertently designed in.Nonetheless,relative to the old methods of pit props and bars,the first generation support was a tremendous forward step and made real con

55、tributions to safety and productivity.</p><p>　　From this first development quite rapid progress was made.A major requirement was to provide a safer travelway through the face for the face operator and this

56、was solved by adding one,or alternatively two,forward legs with their own roof canopies and floor bases to the four leg unit..This also greatly improved the roof control characteristics.</p><p>　　By the earl

57、y 1960s,these articulated supports,with load carrying capacities of up to 180 tonnes,were using substantially improved fabrications and hydraulics.although their application underground was still restricted to seam heigh

58、ts of 1.5 metres.</p><p>　　The worldwide expansion of longwall mining.coupled with a need to extract higher seam ranges,led to a requirement for supports of higher load carrying capacities.Thus the rigid bas

59、e chock was introduced in 1968.This second generation support provided for support ratings of up to 720 tonnes can seam extraction of three metres.</p><p>　　The shield support emerged in the 1970s and the ea

60、rly 2 leg caliper designs were extensively used in Germany and introduced into the USA and South Africa.These shields were poor in efficiency and suffered from very high toe loadings.</p><p>　　The introducti

61、on of lemniscate designs was made in the late 1970s.Shield supports required fundamental changes in design philosophy in that the mechanical linkage resisted strata lateral forces in addition to vertical forces.This prov

62、ided for a far more efficient and reliable support and its robustness allowed for the successful application of the longwall system in strata conditions which had previously been impossible,for example,the extremely heav

63、y conditions of New South Wales,Australia and </p><p>　　The efficiency of the modern shield support provides the suitable environment for successful application of automation.</p><p>　　The prefe

64、rred configuration of shield supports in the USA is the 2 leg design,and this design has been the major platform for many of the automation developments that are currently available.</p><p>　　The configurati

65、on is being introduced into the UK and Australian market and will continue to be in the forefront of roof support and automation development for a long time into the future.</p><p>　　3 ROOF SUPPORT HYDRAULIC

66、S UP TO THE 1980s</p><p>　　Roof support systems use large volumes of fluid both to fill up the system and then to compensate for leakage and other fluid losses.This economic factor coupled to others such as

67、fire hazard and transportation logistics of large volumes of liquids led almost immediately to roof support hydraulic systems becoming water-based.</p><p>　　It is a fact that the use of water-based hydraulic

68、s has been an area of engineering in which the roof support manufactures have truly led the technology and even today,very few manufactures of industrial hydraulic equipment include products suitable for use with water-b

69、ased fluids within their portfolio.</p><p>　　The earliest roof support systems used seal and valve technology that was not at all sophisticated.Simple tap valves and leather seals with string packings were t

70、he best that was available for working at the relatively high pressure of 7MPa.</p><p>　　Engineers soon realized that special valve gear would be needed in order to cater for effects like convergence,to ensu

71、re that legs remained competently set and to simplify the methods of operation.So non-return valves,bleed valves and selector valves soon appeared in order to safeguard the workplace and equipment and to make life easier

72、 for the operators.All the while,valve sealing technologies were slowly improving as manufacturers developed different valve seat forms using various hard and sof</p><p>　　Leg and ram seal technology also ch

73、anged rapidly,with manufactures soon using rubbers of various hardnesses and rubber-fabric composites.</p><p>　　The “dream come true”of the maintenance engineer was the eventual development of the quick-rele

74、ase or staple lock hose fitting which very soon almost universally replaced the threaded connection.</p><p>　　Fluid technology was an area that also created problems.In the beginning there was emulsifying oi

75、l and water.But it was surely never conceived that the water used for mixing could have so many potentially catastrophic effects.Too much hardness, too little hardness,metal salts and bacteria played havoc with water/oil

76、 emulsions,resulting in separation,scumming,filter blockage and ultimately creating severe problems within the equipment..</p><p>　　Abnormally high levels of fluid percentage in the emulsion caused separatio

77、n and scumming,low strengths caused severe corrosion within valve gear and cylinders.</p><p>　　Fluids gradually improved and the recognition of British Coal Spec.18 and Spec.19 waters brought about the devel

78、opment of fluids specific to the hardnesses of waters with which they were to be mixed.</p><p>　　Fluid contamination by particles of dirt has always been a problem underground.It is again only relatively rec

79、ently that breakthroughs have been made.It used to be the case that filter blockage and bypass was accepted and the result was bypassing valves and extreme wear on pumps,unloading valves etc.</p><p>　　Valve

80、gear development continued down the path to automation in the early 1970s with the introduction of sequence,striker and latching valves which formed the basis of hydraulic logic applied to roof supports.Thus it was attem

81、pted to create sequenced operations from a simple control valve initiation movement by the operator.Single supports,some quite complex involving sprags and forepoles,were controlled thus.The technique even extended to hy

82、draulic batch or bank control.In this design,a number </p><p>　　Indeed the first Gullick forerunner of the modern electro hydraulic systems used,in each bank,an initiator chock,which housed the electronics a

83、nd solenoid valves,and 3 slave chocks.In those days hydraulic logic was preferred because the electronics was “too complicated”.In fact the hydraulics was too complicated and the valve gear was usually,by necessity,burie

84、d beneath a mass of hose spaghetti and was a nightmare for the maintenance fitter particularly if the hydraulic fluid was poorly maintain</p><p>　　These early failures of hydraulic and electro hydraulic auto

85、mation led to the demise of automation in the early 1970s,and more simpler systems were reverted to.However development continued and most important of all,the shield support was beginning to emerge.</p><p>

86、　　4 ROOF SUPPORT ELECTRONICS UP TO THE 1980s</p><p>　　As early as 1964 it was realized that electronics held the key to the automation.</p><p>　　A bolt attempt was made within British Coal to pr

87、oduce a fully automated face-including machine initiation-under the ROLF project.</p><p>　　The systems failed not in their endeavour but because the equipment and the roof supports of the day were simply not

88、 suitable.However,the ROLF project provided that one day automation should work.</p><p>　　A lull occurred until the late 1970s where the heavy duty programme of British Coal once again awakened thoughts of a

89、utomation.</p><p>　　Gullich Dobson decided that an hydraulic logic initiator system would stand a chance of success,but had recognized the earlier shortcomings of the inflexible “hard logic”used with ROLF.&l

90、t;/p><p>　　Therefore,the decision to use micro processor for control within the on-face control boxes,and the use of a Gate End computer was a wise one,but not without risk given the relative newness of micropr

91、ocessor technology.</p><p>　　Auto sequential software resided in the Gate End Computer and commands were communicated to the intelligent OFUs to activate solenoid valves,in sequence to pilot operate the roof

92、 supports.</p><p>　　Three Gullick electro-hydraulic faces were installed during the late 1970s and the development culminated in a system,no longer using as much hydraulic bank logic,which controlled roof su

93、pport and conveyor,and also extension bars and sprages.</p><p>　　Another development was coalface alignment,where conveyor straightness and web depth were controlled by micro processor based electronics on t

94、he supports,with a computer in the gate-end and a link to the surface.</p><p>　　Two installations were manufactured and although they suffered from various problems including ingress of water into the ram po

95、sition sensors,they proved the principles of coalface alignment and surface transmission.</p><p>　　5 ROOF SUPPORT CONTROL SYSTEMS UP TO THE PRESENT DAY</p><p>　　The early attempts at automation

96、had proved that the ultimate goal would one day be achieved.Certain conclusions had been reached.</p><p>　　The shield support provided the right environment for the application of automation.</p><

97、p>　　Valve gear would need to be designed that was reliable at high pressures,tolerant to contamination and capable of hign flows.</p><p>　　Legs and rams would need to be capable of high loads,rapid operat

98、ion and suitable for heavy yielding conditions where applicable.</p><p>　　The micro processor was a sensible electronic approach,and that demands for high speed and multiple operations could expose the limit

99、s of intrinsically safe systems which used solenoid valves and simpler hard-wired logic electronics.</p><p>　　Gullick began is development programme for the new generation by addressing conclusions 2. It alr

100、eady had shields,microprocessor and a new generation of legs and rams was already being developed.</p><p>　　Valve gear capable of working at greater than 30MPa,yet low current,was the key ingredient and in 1

101、984 Gullick introduced the motorized valve.This 10 to 20 milliamp pilot valve could work quite happily at 35 MPa and still provide flows comparable to a solenoid valve consuming perhaps 120 MA.Reliability was better than

102、 a solenoid valve due to the smooth operation and high forces available.</p><p>　　The motorized valve allowed the multiple operation limitations of intrinsically safe power supplies to be overcome,allowing a