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中文題目：放頂煤液壓支架設(shè)計(jì)
外文題目：THE DESIGN OF CAVING COAL HYDRAULIC SUPPORT
畢業(yè)設(shè)計(jì)（論文）共77頁（其中：外文文獻(xiàn)及譯文17頁） 圖紙共3張
完成日期 20xx年6月 答辯日期 20xx年6月
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Xxx大學(xué)
本科生實(shí)習(xí)報(bào)告書
教學(xué)單位
專 業(yè)
班 級
學(xué)生姓名
學(xué) 號
指導(dǎo)教師
學(xué)生實(shí)習(xí)報(bào)告：要求對實(shí)習(xí)的主要內(nèi)容、本人學(xué)習(xí)與工作的表現(xiàn)、收獲與體會、以及存在的問題等方面進(jìn)行總結(jié)。
大四下學(xué)期我們來到了遼寧阿爾法液壓有限公司進(jìn)行半個月的實(shí)習(xí)。進(jìn)入車間，看見工人們都在那里認(rèn)真熟練地操作機(jī)器。我們分別被分配到了各條線上，我做的畢業(yè)設(shè)計(jì)題目是放頂煤液壓支架的設(shè)計(jì)，所以我被分到關(guān)于液壓支架的線上，線長找了一個老員工教我，他講了很多關(guān)于液壓支架的知識，并講了如何操作機(jī)器和做產(chǎn)品的步驟，我很虛心的學(xué)習(xí)后便試著者進(jìn)行操作。真是說起來容易做起來難啊，光開關(guān)機(jī)器我就學(xué)了好多次，才能記清步驟。
隨著工作天數(shù)的增加，我也更加適應(yīng)了工作環(huán)境，熟悉了工作要求，但同時也更加了工作量，出現(xiàn)了各種問題。心理上也出現(xiàn)了倦怠的情緒，一個“我”老想著盡快回家，過幾天舒適的生活。另一個“我”則一直為自己加油，鼓勵自己要堅(jiān)持下去。不經(jīng)歷風(fēng)雨，怎能見彩虹。最終，堅(jiān)持戰(zhàn)勝了退縮，我還是一如往常地繼續(xù)認(rèn)真工作。工作當(dāng)中，,有喜有憂。當(dāng)然也有很多收獲。我從其中明白了許多道理。
一：明白了遵守規(guī)則，注意細(xì)節(jié)的重要性。比如有一次我在另外一個部門的人跟走產(chǎn)品后為及時報(bào)工，導(dǎo)致產(chǎn)品數(shù)量減少。幸虧后來我有及時發(fā)現(xiàn)，才沒闖下禍。再比如我們每工作半小時要及時進(jìn)行自檢，否則沖出的產(chǎn)品一旦有問題，就會出現(xiàn)大批量報(bào)廢，有的人一開始還按規(guī)則進(jìn)行，熟悉了就容易忽視，這都是要不得的。所以我認(rèn)為嚴(yán)謹(jǐn)?shù)墓ぷ髯黠L(fēng)，端正的工作態(tài)度都是工作人員應(yīng)該具備的最基本素質(zhì)。我們應(yīng)該壓制住浮躁的心理，從一點(diǎn)一滴的小事做起，踏踏實(shí)實(shí)地工作。
二：懂得了人際關(guān)系和交流溝通的重要性。在工作中，和上級進(jìn)行有效的溝通，和同事處好關(guān)系也都是非常必要的，只有處理好這些，工作起來才會更加順利，心情也會別樣的好。工作時，互相借工具使也非常方便，知道了給予比獲得更令人開心.不論做什么事情,都有主動性和積極性,對成功要有信心,要懷著一顆真誠的心和周圍的人溝通,關(guān)心別人,支持別人。
三：是對工作的熱情和投入。一開始的時候，覺得新鮮，可能不會感覺到很累，可時間久了，我就總是感覺身體疲乏，開始想家了，想念在家的安逸和自由，想干什么干什么。但又想到一開始對自己的承諾，我一定會堅(jiān)持下去。工作的時候，我便很認(rèn)真地去做，什么都不想。就這樣，投入了熱情，忘記了疲憊。就這樣，當(dāng)別的同學(xué)都離開的時候，我還是選擇了繼續(xù)堅(jiān)持，一直到實(shí)習(xí)結(jié)束。
四：我深深地明白了知識的重要性。看到工人們一天一天辛苦的工作，幾乎沒有自由時間，而收入也僅僅是那么悠閑地一點(diǎn)錢。工人們一天天吃飽飯?zhí)铒柖亲泳椭皇菫榱烁苫?，就像被監(jiān)禁了一樣，一天24小時除了上班吃飯，就剩睡覺了。我不禁感嘆，在那些企業(yè)家的眼里，他們也許就只是用來賺錢的工具吧。顯然，一輩子光靠打工來謀求生存顯然是不可能的，體力是有限的，所創(chuàng)造的價值也是有限的。而腦力是無限的，所創(chuàng)造的社會財(cái)富更是無窮的。對社會的貢獻(xiàn)更大，社會回饋給你的回報(bào)自然就會越多。還有就是時間觀念．工廠的時間觀念特別的強(qiáng)，一分一秒就是一分一秒，涉及到時間就與錢掛勾．你遲到或者早退都是要扣工資的，不像在學(xué)校拖拖拉拉的沒有一點(diǎn)緊迫感，無非就是被老師批評幾句，不痛也不癢．知識無價，大學(xué)學(xué)習(xí)的機(jī)會來之不易，我們要好好珍惜，用知識來武裝自己，豐富自己。
五：這次實(shí)習(xí)同時也培養(yǎng)了我吃苦耐勞的精神，磨練了我的意志力。有這樣一句詩：寶劍鋒從磨礪出，梅花香自苦寒來。經(jīng)過這次，我更加深刻地明白了其中所包含的真諦。不經(jīng)歷風(fēng)雨，怎能見彩虹。我愿意接受任何困難的洗禮，保持一顆積極向上的心，去迎接未來的挑戰(zhàn)。
指
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成績評定： 指導(dǎo)教師簽字：
20xx 年 3月 20日
實(shí)習(xí)單位意見
負(fù)責(zé)人簽字：
（單位蓋章）
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注：實(shí)習(xí)結(jié)束時，由實(shí)習(xí)學(xué)生填寫本表后，交指導(dǎo)教師和實(shí)習(xí)單位簽署意見，最后交所在教學(xué)單位歸檔保管。
Xxx大學(xué)
本科畢業(yè)設(shè)計(jì)（論文）開 題 報(bào) 告
題 目 放頂煤液壓支架
指 導(dǎo) 教 師
院（系、部）
專 業(yè) 班 級
學(xué) 號
姓 名
日 期
教務(wù)處印制
一、 選題的目的、意義和研究現(xiàn)狀
目的：
本次畢業(yè)設(shè)計(jì)的目的是培養(yǎng)我綜合運(yùn)用液壓傳動、機(jī)械設(shè)計(jì)、工程理學(xué)等課程中所學(xué)理論知識的能力；強(qiáng)調(diào)設(shè)計(jì)的獨(dú)創(chuàng)性和實(shí)用性，培養(yǎng)和提高設(shè)計(jì)者獨(dú)立分析問題和解決實(shí)際問題的能力，為今后適應(yīng)工作崗位和創(chuàng)造性地開展工作打下堅(jiān)實(shí)基礎(chǔ)。在設(shè)計(jì)過程中，通過運(yùn)用各方面的知識來達(dá)到熟悉和掌握知識的目的。
意義：
通過這次畢業(yè)設(shè)計(jì)來加深我對所學(xué)知識的理解，達(dá)到能自主設(shè)計(jì)的能力。同時這也是對學(xué)我的一次畢業(yè)前的考核，只有通過了這次綜合性的畢業(yè)設(shè)計(jì)，才能證明我已經(jīng)掌握相關(guān)的知識能力。這也是學(xué)校對社會輸送人才的一種負(fù)責(zé)的態(tài)度，只有通過了畢業(yè)設(shè)計(jì)考核才能予以畢業(yè)，才能為建設(shè)國家做出貢獻(xiàn)。
研究現(xiàn)狀和存在問題：
綜合機(jī)械化開采運(yùn)用到放頂煤開采工作面后， 是放頂煤開采集輸進(jìn)入到了一個新的發(fā)展階段。由于工作面有液壓支架實(shí)現(xiàn)可靠快速的支護(hù)，放頂煤作業(yè)在安全可靠的情況下進(jìn)行明顯提高了工作面產(chǎn)量。經(jīng)過近20年的經(jīng)驗(yàn)積累和發(fā)展，綜采已經(jīng)成為國內(nèi)主要開采技術(shù)隨之而來的是大量需求配套液壓支架， 因此研制新型高效液壓支架已經(jīng)迫在眉睫。
液壓支架的研制在很大程度上提高了我國采煤機(jī)械化水平。液壓支架是有液壓元件與金屬構(gòu)件組成的支護(hù)和控制頂板的設(shè)備，以高壓液體作為動力，實(shí)現(xiàn)支撐、切頂、移架和推移輸送機(jī)等一整套工序。實(shí)踐表明液壓支架具有支護(hù)性能好、強(qiáng)度高、移架速度快、安全可靠等優(yōu)點(diǎn)綜合機(jī)械化采煤設(shè)備是有液壓支架與可彎曲輸送機(jī)和采煤機(jī)組成可增加采煤工作面產(chǎn)量、提高勞動生成率、降低成本、減輕工人體力勞動和保證安全生產(chǎn)。放頂煤液壓支架的存在問題：我國雖然在放頂煤液壓技術(shù)方面取得了一些成績，但是相對于發(fā)達(dá)國家而言，還存在不足:第一，我國的綜采范圍和落后的技術(shù)與產(chǎn)煤第一大國的地位不對應(yīng)。第二，我國的放頂煤液壓控制技術(shù)水平還比較落后。我國傳統(tǒng)材料、工藝、性能與世界發(fā)達(dá)國家還是存在很大的差距。第三，我國的放頂煤液壓支架控制系統(tǒng)研究比較落后，嚴(yán)重制約了支架的移動速度和經(jīng)濟(jì)效益的提高?，F(xiàn)在我國放頂煤液壓支架還是基本采用手動先導(dǎo)程序控制。近年來，計(jì)算機(jī)輔助設(shè)計(jì)技術(shù)的廣泛使用，極大地提高了放頂煤液壓支架設(shè)計(jì)水平，但仍然存在一些突出問題，主要有以下幾點(diǎn):y目前廣泛使用的有限元分析法由于建模困難，只能對個別部件進(jìn)行分析，無法對整架分析。(2)由于缺少對整體強(qiáng)度的分析，導(dǎo)致對不同工況下支架受力趨勢分析不明確。(3)在使用接觸法計(jì)算處理各個組件的連接問題時，往往由于接觸面選擇困難，使分析效率低下。
二、 研究方案及預(yù)期結(jié)果
本論文主要對由實(shí)現(xiàn)支撐功能結(jié)構(gòu)、實(shí)現(xiàn)推溜移柱功能的結(jié)構(gòu)、實(shí)現(xiàn)液壓支架自動移動功能的結(jié)構(gòu)、以及實(shí)現(xiàn)放頂煤液壓支架的總體方案設(shè)計(jì)。具體內(nèi)容包括以下幾部分：
1液壓支架基本參數(shù)的確定
2雙四連桿機(jī)構(gòu)的設(shè)計(jì)
3頂梁及其底座的設(shè)計(jì)
4立柱結(jié)構(gòu)的設(shè)計(jì)
5推移千斤頂?shù)倪x擇
6支架液壓系統(tǒng)的擬定
7立柱、掩護(hù)梁和底座的驗(yàn)算
三、 研究進(jìn)度
第三～四周 任務(wù)分析 查閱相關(guān)資料；
第五～六周 綜合實(shí)習(xí)，謀劃設(shè)計(jì)安排，完成開題報(bào)告
第七～八周 總體方案設(shè)計(jì)
第九～十周 總體設(shè)計(jì)
第十一～十二周 關(guān)鍵部件結(jié)構(gòu)設(shè)計(jì)
第十三～十八周 撰寫論文完成相關(guān)圖的設(shè)計(jì)
四、 主要參考文獻(xiàn)
[1]王洪林.放頂煤液壓支架的發(fā)展?fàn)頪J].煤炭技術(shù),2007,(01):11-12.
[2]黃尚智,樊運(yùn)策.推進(jìn)我國放頂煤液壓支架改革的建議[J].煤礦開采,2007,(06):8-13+32.
[3]孔德冒,鄭豐隆,張優(yōu)明.放頂煤液壓支架總體設(shè)計(jì)[J].煤礦機(jī)械,2008,(09):23-24.
[4]劉海東,張躍峰.放頂煤液壓支架的發(fā)展?fàn)顩r[J].煤炭技術(shù),2008,(11):19-20.
[5]王國法,劉俊峰,任懷偉.大采高放頂煤液壓支架圍巖耦合三維動態(tài)優(yōu)化設(shè)計(jì)[J].煤炭科學(xué)技術(shù),2011,(04):84-88+54
[6]石哲敏,陳新中,許日成,范迅.低位放頂煤液壓支架頂梁的有限元分析[J].煤礦機(jī)械,2012,(06):101-103.
[7]張銀亮,王國法,賈德峰.綜采放頂煤工作面提高回采率與降塵的研究[J].煤礦開采,1999,(01):9-11+23+62.
[8]趙喜敬,于淑政,范進(jìn)楨,孫會來.低位放頂煤液壓支架的運(yùn)動模擬分析[J].礦山機(jī)械,2000,(05):25-26+2-4.
[9]王朝陽,焦成堯,范衛(wèi)星,彭銘.低位放頂煤液壓支架在大傾角厚煤層中的應(yīng)用[J].煤炭技術(shù),2001,(01):4-13.
[10]金太,劉長友.放頂煤液壓支架的動態(tài)承載特征及其可靠性分析[J].礦山壓力與頂板管理,2003,(S1):1-4.
[11]劉長友,金太.放頂煤液壓支架的動態(tài)承載特征及可靠性分析[J].礦山壓力與頂板管理,2005,(01):1-3+6-118.
[12]孫公贊,張曉東,樊軍.兩柱與四柱放頂煤液壓支架架型及結(jié)構(gòu)淺析[J].煤礦機(jī)械,2009,(02):167-169.
[13]王國法.液壓支架技術(shù)體系研究與實(shí)踐[J].煤炭學(xué)報(bào),2010,(11):1903-1908.
[14]何風(fēng)強(qiáng),李宏,王東攀.四柱放頂煤液壓支架立柱受力不均衡規(guī)律及機(jī)理研究[J].煤礦開采,2012,(06):35-37.
[15]謝錫純.李曉豁.《礦上機(jī)械與設(shè)備》.中國礦業(yè)大學(xué)出版社.第二版.2007.8
[16]魯忠良.景國勛.肖亞寧.《液壓支架設(shè)計(jì)使用安全辨析》.煤炭工業(yè)出版社.2006
[17]王啟廣.李炳文.黃嘉興.《采掘機(jī)械與支護(hù)設(shè)備》.中國礦業(yè)大學(xué)出本社.2006.4
[18]王國法.《高端液壓支架及先進(jìn)制造技術(shù)》.煤炭工業(yè)出版社.2010.7
[19]Gonzalez Nicieza, Menendez Diaz. Analysis of support by hydraulic props in a longwall working [J].International Journal of Coal Geology, 2008, 74(1): 12-16.
[20]Maloszewski. hydraulic support design formine coal[J]. International Journal of Rock Mechanics and MiningSciences & GeomechanicsAbstracts. 1980, 17(4):70-71.
五、 指導(dǎo)教師意見
指導(dǎo)教師簽字：
摘 要
?
本文對國內(nèi)外放頂煤開采技術(shù)發(fā)生歷史及現(xiàn)狀進(jìn)行了綜合闡述，對放頂煤液壓支架進(jìn)行了分類和對其各種形式研究；介紹了每種形式放頂煤液壓支架各適應(yīng)的煤層條件；并結(jié)合神東四盤區(qū)的現(xiàn)狀，設(shè)計(jì)適用于煤層厚度5.35-9.86，平均采高8.9米滿足頂板、地板條件的放頂煤液壓支架.形成滿足神東現(xiàn)狀的放頂煤開采技術(shù)理論。
通過對現(xiàn)有放頂煤液壓支架的分析，優(yōu)勢對比，設(shè)計(jì)出適合的結(jié)構(gòu)形式，最后對立柱、頂梁、掩護(hù)梁和底座進(jìn)行了強(qiáng)度校核計(jì)算。
關(guān)鍵字：放頂煤液壓支架；立柱；頂梁；掩護(hù)梁；底座；放煤機(jī)構(gòu)。
2
Abstract
In this paper on the domestic and foreign technology of top coal caving mining occurred history and current situation has been discussed, on the roof caving coal hydraulic support the classification and research in its various forms; introduced each kind of form of roof caving coal hydraulic support the adaptation conditions of coal seam; Shendong four disc area and combined with the status quo, designed for coal seam thickness 5.35-9.86, collect on average 8.9 meters high and meet the conditions of roof and floor of top coal caving hydraulic support. Formed to meet the Shendong status of top coal caving mining technology in theory.
Through the analysis of the existing roof caving coal hydraulic support, comparative advantages of design for the structural form, strength check and calculates the column, a top beam and a shield beam and a base at the end of paper.
Keywords: Caving hydraulic support；Column; beam; shield; base;
coal caving mechanism.
附錄A
摘要：根據(jù)綜采工作面實(shí)際工作情況，我們提出了采煤工作面液壓支架和刨煤機(jī)兩者運(yùn)行關(guān)系的一個公式，并在此基礎(chǔ)上，建立了工作面液壓支架和刨煤機(jī)的自動化控制系統(tǒng)。我們介紹了采煤工作面液壓支架控制的系統(tǒng)工作原理。我們歸納了本控制系統(tǒng)的三個參數(shù)：反應(yīng)速度，可靠性和易維護(hù)性。同樣，我們簡要介紹了它的主控制器與附屬控制器和由單總線實(shí)現(xiàn)的通信系統(tǒng)。我們實(shí)驗(yàn)室建造和測試了10個控制器。結(jié)果表明，該控制模型是可行的，符合實(shí)際情況。它為長壁工作面的液壓支架計(jì)算機(jī)控制系統(tǒng)的設(shè)計(jì)提供了理論依據(jù)。
關(guān)鍵詞：長壁工作面,液壓支架,參數(shù),自動控制
1. 引言
在我國采高0.7-1.3米的薄煤層可開采的儲量超過6億噸，大約占我國總儲量的百分之十八。因?yàn)楸∶簩硬擅簷C(jī)結(jié)構(gòu)的限制，0.8米是采煤機(jī)最低開采高度，而且，這么低的空間下采煤機(jī)也不便于工人操作和維護(hù)。因此，刨煤機(jī)成為薄煤層開采的主要設(shè)備。然而，薄煤層工作面空間狹小。雖然工人不需要在刨煤機(jī)后工作，但他們?nèi)匀恍枰僮饕簤褐Ъ芟到y(tǒng)。這不僅是一個安全隱患，而且移架的速度遠(yuǎn)未達(dá)到的刨煤機(jī)速度，嚴(yán)重制約著綜采工作面效率和產(chǎn)出 [ 2 ]。
液壓支架不僅是支護(hù)設(shè)備，但它也是綜采工作面的一個重要設(shè)備。隨著電子計(jì)算機(jī)和自動控制自動化技術(shù)的發(fā)展，采礦設(shè)備的不斷改善，電液控制技術(shù)也將在液壓支架上逐步應(yīng)用。電液控制系統(tǒng)不僅可以自動控制液壓支架的動作，而且還實(shí)現(xiàn)鄰架控制或遠(yuǎn)程控制。因此，綜采工作面的自動化，完全無人化，完全可以會實(shí)現(xiàn)。所以，綜采工作面的自動化成了應(yīng)探討的重要問題[ 3 ]。
2. 液壓支架自動化控制系統(tǒng)模型及刨煤機(jī)的約束參數(shù)
2.1液壓支架和刨煤機(jī)之間的制約關(guān)系
在刨煤機(jī)和采煤機(jī)是兩個不同的采煤設(shè)備。同采煤機(jī)相比，刨煤機(jī)主要適用于薄煤層。其結(jié)構(gòu)簡單、截深小、牽引速度快。因此，我們將討論不同于采煤機(jī)的刨煤機(jī)和液壓支架之間的制約關(guān)系，我們假定下面的采煤工作面地質(zhì)條件良好：硬度系數(shù)低于21°，傾角小，薄煤層的頂板穩(wěn)定。
下列是為采煤工作面提供的機(jī)械設(shè)備：刨煤機(jī)，刮板鏈?zhǔn)捷斔蜋C(jī)和液壓支架。字母“ P ”代表刨煤機(jī)截割深度（100毫米）和“ q ”是液壓支架的推移距離（600毫米）。上面列出的是討論刨煤機(jī)、液壓支架和刮板鏈?zhǔn)捷斔蜋C(jī)之間的制約關(guān)系所做的假設(shè)。
圖一表示的是刨煤機(jī)在工作面上利用往復(fù)運(yùn)動采煤，兩架液壓支架在刨煤機(jī)后推移輸送機(jī)，每個支架推移的距離是(mm)，每程是。刮板輸送機(jī)沿著某一曲線彎曲。液壓支架推動刮板輸送機(jī)兩次后達(dá)到切割深度p （毫米）。當(dāng)刨煤機(jī)在工作面完成一次截割。刨煤機(jī)在工作面上開采時間后液壓支架能推移刮板輸送機(jī)半程的距離。此液壓支架完成比其他沒有推移的支架一半推移行程。
圖一
上文提到的就是液壓支架和刨煤機(jī)之間的制約因素。為了獲得液壓支架和刨煤機(jī)之間的制約關(guān)系，變量和函數(shù)的定義如下：
1) 綜采工作面液壓支架數(shù)在從左至右依次為： 1 ， 2 ， 3 ， ... ， (n–1), n;
2) v：刨煤機(jī)速度，采煤速度; x：刨煤機(jī)采過距離，即從工作面左側(cè)到刨煤機(jī)中心的距離（見圖-1 ） 。
刨煤機(jī)采過距離x轉(zhuǎn)化為位移K可用液壓支架數(shù)目來計(jì)算，這與刨煤機(jī)中心一致。假設(shè)t= ，且 = 0 ，其中V是速度的刨煤機(jī)（米/秒） ; b是兩個相鄰液壓支架中心之間的距離（米） 。
3) 方向是從左向右前進(jìn)，反之亦然。刨煤機(jī)運(yùn)動方向由變量y表示：
4) 支架的動作定義為，可以表示單一動作，如升架，降架，移架和推動刮板輸送機(jī)等等，它也可以代表由幾個單一動作組成的聯(lián)合動作，如降價，移架，升架，下腳標(biāo)表示某個動作（i = 1 ， 2 ， 3 ） 。三種動作的符號的定義如下：
f1： 動作1 （推移截深的一半）;
f2： 動作2 （推移一個截深距離）;
f3： 降架--移架--升架
5) 定義的動作功能。當(dāng)液壓支架M執(zhí)行動作，我們定義如下：
?M (4)
其中，代號為“ ? ”是指操作。
f1 ? K1:：支架K1 動作1 （推移截深的一半） ;
f2 ? K2：支架K2 動作2 （推移一個截深） ;
f3 ?：支架降架-移架-升架
這11個動作統(tǒng)一表示為：
“ S ”的是刨煤機(jī)移動的距離（毫米）。
當(dāng)刨煤機(jī)在工作面往返采煤時液壓支架首先執(zhí)行動作f1和f2 ，動作執(zhí)行完成半程后，執(zhí)行動作f3。
6) 相對距離，根據(jù)液壓支架的數(shù)目，執(zhí)行動作的液壓支架Ki，刨煤機(jī)的中心ΔK ，?Ki=|K–Ki|。 ΔKi與刨煤機(jī)的中心有關(guān)（當(dāng)位置已知）。?Ki對于工作面是一個常量。我們從圖二和條件三和?Ki的定義得到：
從表達(dá)式(2)、(5)、(6)我們可以得到：
表達(dá)式（8）是液壓支架和刨煤機(jī)制約因素之間的數(shù)學(xué)關(guān)系。它表達(dá)液壓支架間的動作的關(guān)系，和刨煤機(jī)行程，刨煤機(jī)運(yùn)行方向。支架Ki 刨煤機(jī)中心的距離沒有變化，當(dāng)開采時液壓支架分別對應(yīng)不同的刨煤機(jī)運(yùn)動距離x執(zhí)行3個不同的動作 。
圖二
2.2液壓支架和刮板輸送機(jī)之間的制約因素
? 每個液壓支架推移千斤頂與刮板輸送機(jī)相連，由推移千斤頂推移刮板輸送機(jī)。刮板輸送機(jī)按照一定的曲線減少在運(yùn)動時彎曲點(diǎn)的磨損。刮板輸送機(jī)要保持靈活以減少半程的牽引阻力。
2.3液壓支架自動化控制模型
實(shí)際上，方程（7）及（8）是支架位置自動化控制模型的表達(dá)式，其中刨煤機(jī)的行程（ x或K）作為一個變量。由液壓支架數(shù)目計(jì)算（支架數(shù)目K相當(dāng)于刨煤機(jī)中心）位移K當(dāng)刨煤機(jī)來回往復(fù)可以變化。以與刨煤機(jī)中心一致的液壓支架K為基準(zhǔn)，一套支架相對支架K的位置不會改變。把i，y帶入公式（8）,自動控模型可以描述為：
1 ）當(dāng)刨煤機(jī)向右運(yùn)動時，液壓支架K - ΔK1移動1 / P的行程，支架K - ΔK2移動2 / P的行程;液壓支架K-Δ執(zhí)行降架-移架-升架（在這一點(diǎn)上，支架完成了行程的一半） 。
2 ）當(dāng)刨煤機(jī)向左運(yùn)動時，支架K+ΔK1移動1 / P的行程;支架K+?K2移動2 / P的行程;支架K+Δ執(zhí)行降架-移架-升架（在這一點(diǎn)上，支架完成了行程的一半） 。
K是由按鍵操作的液壓支架的數(shù)目;
ΔK1 -Δ是距正在執(zhí)行動作的支架到支架K的距離[ 5-9 ]
3. 系統(tǒng)的原理結(jié)構(gòu)
如圖-3所示，每個液壓支架都由附屬控制器控制和形成一套電液控制附屬系統(tǒng)。 COM端口的主要控制器及所有附屬控制器連接到一個通信總線，它構(gòu)成了綜采工作面液壓支架微機(jī)電系統(tǒng) [ 5 ] 。
圖三
1）系統(tǒng)的響應(yīng)速度迅速：主控制器和附屬控制器之間的通信，或中下級控制器是直接的，因?yàn)镃OM端口的主控制器和任何附屬控制器都連接到單總線，因此從屬控制器之間的響應(yīng)速度迅速。
2 ）快速系統(tǒng)的可靠性：在一個單總線通信系統(tǒng)，如果主控制器或下級控制器故障整個系統(tǒng)將不會受到影響仍能夠正常工作。除非控制器遭破壞，主控制器或下級控制器才受到影響，這種情況很少發(fā)生。單一通信總線系統(tǒng)是相當(dāng)可靠的。
3）系統(tǒng)維護(hù)：關(guān)掉電源后的主控制器或從屬控制器的維修就可以執(zhí)行了，附屬控制器液壓系統(tǒng)的可以維修和部件可以被替換。這種維修不影響系統(tǒng)正常工作，系統(tǒng)維護(hù)方便。
4. 主控制器和附屬控制器的功能和系統(tǒng)通信
每臺液壓支架配備的附屬控制器是電液控制系統(tǒng)的核心。附屬控制器監(jiān)測記錄所在液壓支架數(shù)據(jù)，如支架的動作等，翻譯和編輯這些數(shù)據(jù)，并對支架發(fā)送控制命令 [ 3 ]。
綜采工作面COM端口的主控制器和所有附屬控制器連接到通信總線，可實(shí)現(xiàn)統(tǒng)一管理，并建立系統(tǒng)的控制參數(shù)。
該系統(tǒng)已通過單總線，連接不同的附屬控制器到網(wǎng)絡(luò)。附屬控制器從單一總線發(fā)送和接收控制信號監(jiān)測和控制所在液壓支架的動作和之間實(shí)現(xiàn)控制。綜采工作面主控制器初始化系統(tǒng)和設(shè)置參數(shù)，并從單一總線收集信號實(shí)現(xiàn)集中檢查和系統(tǒng)的距離顯示。
5.結(jié)論
? 在這項(xiàng)研究中，我們已經(jīng)提出了液壓支架和刨煤機(jī)之間運(yùn)行制約因素的一個數(shù)學(xué)表達(dá)式。我們建立了一個液壓支架的自動控制模型并介紹了電液控制系統(tǒng)的基本原理，以及主控制器及附屬控制器的功能。我們在實(shí)驗(yàn)室建造了十套從屬控制器，實(shí)驗(yàn)表明，該控制模型符合實(shí)際要求。
附錄B
Mathematical model of electric hydraulic and powered support control system at a plough mining face
ZHANG Wei, HAN Xiao, SUN Jing-jing
School of Mechanical Electronic and Information Engineering, China University of Mining & Technology, Beijing 100083, China
Abstract: Given the actual working of a fully mechanized plough at a mining face, we have proposed a formula for running constraints between powered supports and a coal plough under assumed geological conditions of the coal face and, on this basis, established an automatic control model of powered supports for the coal plough face. We introduced the working principle of the powered support control system of the plough at the mining face. We established three advanced characteristics of this control system: response speed, reliability and easy maintenance of the system. .As well, we briefly introduced, the principal function of primary and subordinate controllers and the realization of the communication system by a Single Bus. Ten controllers were constructed and tested in our laboratorium. The results show that the control model is practical and meets actual conditions. It provides a theoretical basis for designing a computer control system for a powered support system of a plough at a mining face.
Key words: plough mining face; powered supports; constraints; automatic control model
1 Introduction
More than six billion tonnes of thin seam mineable reserves with a shearing height of 0.7–1.3 m, are available in China, which is about 18 percent of the total reserves of our country. With a thin seam shearer, 0.8 m is the lowest mining limit because of its structural restrictions. Furthermore, the shearer is inconvenient for workers to operate and maintain and workers have to work under conditions of extremely low space with this machine[1]. Therefore, coal ploughs become major pieces of equipment for mining thin seams. However, the space of a thin seam is narrow and small. Although workers do not need to work following the coal plough, they still need to operate the powered support system. Not only is there a hidden safety problem, but also the speed of moving the supports artificially falls far short of the speed of the coal plough, seriously restricting the efficiency and output at the mining face[2] .
The powered support system is the support equipment but it is also one of the major pieces of equipment at a fully mechanized coal face. With the development of electronic computers and automatic control technology, the automation of mining equipment is continually improving and simultaneously the electric hydraulic control technology of powered support systems is also developing. The electric hydraulic control system of powered support can not only control the action of the support system automatically, but also realize adjacent or long-range control. Thus the potential of an automated mining face, operated without human hands, may be realized. Therefore, its application to a fully mechanized coal face should be explored for its important implications[3]
2 Automatic control model of powered support system and its constraints on the coal plough
2.1Constraints between powered support system and coal plough
The coal plough and the shearer are two different mining machines. Compared with a shearer, coal ploughs are mainly applied with thin seams. Their structure is simple, the cutting depth is thin and the draught speed is quick. Therefore, the constraints between powered supports and a coal plough, which will be discussed by us, are different from that between powered supports and a shearer. We assume the following geological conditions to prevail at the coal face: the hardness coefficient is below 21°, the dip angle is small and the thin ceiling of the seam is steady[4] .
The following mechanical pieces of cutting equipment are provided for the coal face: a coal plough, a flexible chain conveyor and powered supports. Let the letter “p” represent the cutting depth of the coal plough (100 mm) and “q” the stroke of the cylinder (600 mm) of the support pusher. The constraints among the coal plough, powered supports and the flexible chain conveyor will be discussed under the assumptions listed above.
As shown in Fig. 1, when the coal plough is mining coal by drawing back and forth along the face, the system of two supports push the conveyor behind the plough and each of these supports pushes the conveyor (mm), which is per stroke. The scraper conveyor bends along a certain curve. Supports manage to push the conveyor to the cutting depth p (mm) after having pushed the conveyor two times when the coal plough finishes mining a draught once along the coal face. Supports manage to push the conveyor a distance of half stroke after the plough has mined integer times along face. The supports that have finished a half stroke perform a lower-advance-set operation every other support. The mention above is the constraints between supports and the coal plough.
In order to obtain the constraints between supports and the coal plough, variables and functions are defined as follows:
1）Number powered supports at the mining face from left to right: 1, 2, 3, …, (n–1), n;
2）v: speed of plough, mining coal; x: displacement of plough, i.e., the distance from the left of the face to the center of the plough (see Fig. 1).
The displacement x of the plough is converted into displacement K calculated by support number, which corresponds with the center of the plough. Suppose that t = , and = 0, where v is the speed of the coal plough (m/s); b is the distance between two centers of adjacent supports (m).
3）The direction from left to right is forward and vice versa. The direction of the plough movement is denoted by the variable y:
4）The support acts are denoted by , which can represent a single action, such as setting the leg, lowering the leg, moving and pushing the conveyor and so on; it can also represent a combined action composed of several single acts, such as lower-advance-set. The subscript shows action i (i=1, 2, 3). The symbols of the 3 actions are defined as follows:
f1: act1 (half of a cutting depth is pushed);
f2: act2 (a cutting depth is pushed);
f3: lower-advance-set operation.
5）Define action function. When support M carries out action , we define:
?M (4)
where the symbol “?” means operating.
f1 ? K1: support K1 act1 (half of a cutting depth is pushed);
f2 ? K2: support K2 act2 (a cutting depth is pushed);
f3 ?: support （lowing-advancing-setting;
These 11 actions are expressed in a united way:
where “s” is the moving distance of the plough (mm).
6) The relative distance, calculated by support number, between the support performing action i and the center of the plough is denoted by ?K , where ?Ki=|K–Ki|. ?Ki is related to the position of the center of the plough (confirmed when its position is known). ?Ki is a constant for a certain face. We know from Fig. 2, condition (3) and the definition of ?Ki that:
Eq.(8) is the mathematical expression of the constraints between powered supports and the coal plough. It expresses the relation between action of the supports, the displacement and the moving direction of the coal plough. Support Ki, whose distance to the center of the plough ?Ki never changes, performs 3 different actions fi separately with various displacements x (or K) of the plough while mining coal.
2.2 Constraints between powered supports and scraper conveyor
Every pusher cylinder of a support is connected to a section of the ledge of the conveyor, and the pusher jack makes a move. The conveyor is required to bend according to a certain curvature in order to decrease abrasion at the point of flexure while moving. The conveyor is ensured to be flexible in order to decrease traction resistance after half of a stroke.
2.3 Automatic control model of powered supports
Actually, the Eqs.(7) and (8) are automatic control models of the support location of the plough, which takes the displacement of the plough (x or K) as a variable. The displacement K calculated by the support number (the support number K corresponds to the center of plough pull) changes while the plough is mining coal back and forth. Taking the support K which corresponds with the the center of the plough pull as a benchmark, a set of supports whose locations do not alter relative to support K perform their corresponding actions according to the constraints. By putting i and y into Eq.(8), the automatic control model can be described:
When the plough moves to the right, the support K–?K1 moves 1/p of a stroke; the support K–?K2 moves 2/p of a stroke; the support K–Δperforms lower-advance-set operation (At this point, the supports have accomplished half of a stroke).
When the plough moves to the left, the support K+?K1 moves 1/p of a stroke; the support K+?K2 moves 2/p of a stroke; the support K+Δ performs a lower-advance-set operation (At this point, the supports have accomplished half of a stroke).
K is the support number worked by the key-press operation;
?K1–Δ is the distance calculated by support number between performing support and support K[5–9] .
3 System principle structure
As shown in Fig. 3, every support is controlled by a subordinate controller and forms an electric hydraulic control subordinate system. COM ports of the primary controller and all subordinate controllers are connected to a communication bus, which constitutes the microcomputer distribution system of powered supports at a fully mechanical coal face[5].
Advanced response speed of the system: communication between principal controller and subordinate controllers, or among subordinate controllers is direct because the COM ports of the primary controller and any subordinate controllers are connected to a Single Bus and hence the response speed of control among subordinate controllers is advanced.
Advanced reliability of the system: in a Single communication Bus system, the normal work of the entire system will not be affected if the primary or a subordinate controller has trouble. Only the broken-down controller, either primary or subordinate, is affected and this incidence is remote. The Single communication Bus system is fairly reliable.
Maintenance of the system: after switching off electricity to the primary or subordinate controller, maintenance, can be performed, the hydraulics of the subordinate system can be maintained and components can be replaced. This maintenance does not affect the normal work of the system and is convenient for the system.
4 Function of subordinate and primary controllers and system communication
Every support is equipped with a subordinate controller which is at the heart of the electric hydraulic control system of powered supports. The subordinate controller monitors data about its own powered support, such as running tension, support action and so on, translates and edits these data and sends out control commands to the support[3]
COM ports of the primary and all subordinate controllers at the mining face are connected to a communication bus, which can realize comprehensive management and establishes system control parameters.
The system has adopted a Single Bus, which links the separate subordinate controllers to a network. The subordinate controller monitors and controls the movements of its own support and sends out and receives control signals from the Single Bus to realize controls among subordinate controllers. The primary controller at a mining face initializes the system and sets up parameters and collects signals from the Single Bus to realize centralized inspection and a display of the state of the system.
5 Conclusions
In this study, we have proposed a mathematical expression of the running constraints between powered supports and a coal plough. We established an automatic control model of powered support and introduced the essential principle of an electric hydraulic control system as well as the function of a primary controller and subordinate controllers. Ten sets of subordinate controllers were constructed in our laboratorium and our experiment shows that the control model agrees with practical considerations.
Acknowledgements
Our deepest gratitude goes first and foremost to the Education Bureau, which gives us the chance to do the research. Second, we wish to express our appreciation to many people who have greatly contributed to or helped with the development of this article in their special ways. We are especially grateful to a friend named Tom, who has given us much help in the revision of the article. Our gratefulness also goes to those friends who have given us much inspiration and many constructive suggestions.