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編號：（ ）字 號
本科生畢業(yè)設(shè)計
薄煤層采煤機(jī)截割部設(shè)計
李虎 21040206
機(jī)械工程及自動化04-1班
題目：
姓名： 學(xué)號：
班級：
二〇〇八年六月
中國礦業(yè)大學(xué)畢業(yè)設(shè)計任務(wù)書
學(xué)院 應(yīng)用技術(shù)學(xué)院 專業(yè)年級 機(jī)自04級 學(xué)生姓名 李虎
任務(wù)下達(dá)日期： 2008 年 03 月 16日
畢業(yè)設(shè)計日期： 2008 年 03月 18日至 2008 年 06月 10日
畢業(yè)設(shè)計題目： 薄煤層采煤機(jī)截割部設(shè)計
畢業(yè)設(shè)計專題題目：
畢業(yè)設(shè)計主要內(nèi)容和要求：
設(shè)計參數(shù)：
總裝機(jī)功率：487 KW
截割部功率：200 KW
采高范圍：1.3～2.6m
滾筒直徑：φ1.1m
滾筒截深：630 mm
滾筒轉(zhuǎn)速：40 r/min
電機(jī)轉(zhuǎn)速：1476 r/min
額定電壓：1140 V
具體要求如下：
1、要完成畢業(yè)設(shè)計圖紙3張零號圖紙；
2、按學(xué)校統(tǒng)一要求打印、裝訂設(shè)計說明書，說明書正文70頁左右；
3、中英文摘要400字；
4、參考文獻(xiàn)20篇左右。
院長簽字： 指導(dǎo)教師簽字：
中國礦業(yè)大學(xué)畢業(yè)設(shè)計指導(dǎo)教師評閱書
指導(dǎo)教師評語（①基礎(chǔ)理論及基本技能的掌握；②獨立解決實際問題的能力；③研究內(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；⑤工作態(tài)度及工作量；⑥總體評價及建議成績；⑦存在問題；⑧是否同意答辯等）：
成 績： 指導(dǎo)教師簽字：
年 月 日
中國礦業(yè)大學(xué)畢業(yè)設(shè)計評閱教師評閱書
評閱教師評語（①選題的意義；②基礎(chǔ)理論及基本技能的掌握；③綜合運用所學(xué)知識解決實際問題的能力；③工作量的大小；④取得的主要成果及創(chuàng)新點；⑤寫作的規(guī)范程度；⑥總體評價及建議成績；⑦存在問題；⑧是否同意答辯等）：
成 績： 評閱教師簽字：
年 月 日
中國礦業(yè)大學(xué)畢業(yè)設(shè)計答辯及綜合成績
答 辯 情 況
提 出 問 題
回 答 問 題
正 確
基本
正確
有一般性錯誤
有原則性錯誤
沒有
回答
答辯委員會評語及建議成績：
答辯委員會主任簽字：
年 月 日
學(xué)院領(lǐng)導(dǎo)小組綜合評定成績：
學(xué)院領(lǐng)導(dǎo)小組負(fù)責(zé)人：
年 月 日
摘 要
本文介紹了采煤機(jī)的發(fā)展歷史、組成及工作原理，在分析煤炭工業(yè)及煤炭工業(yè)的行業(yè)背景的基礎(chǔ)上，展望了采煤機(jī)的發(fā)展趨勢，并針對采煤機(jī)的發(fā)展現(xiàn)狀，進(jìn)行了 MG200/487 型采煤機(jī)的截割部設(shè)計。
本文首先確定了設(shè)計方案和選擇了基本部件并開展了傳動系統(tǒng)的可靠性分析，MG200/487型采煤機(jī)截割部主要是由一個減速箱和四級齒輪傳動組成，截割部電機(jī)放在搖臂內(nèi)橫向布置，電動機(jī)輸出的動力經(jīng)由三級直齒圓拄齒輪和行星輪系的傳動，最后驅(qū)動滾筒旋轉(zhuǎn)。并對所設(shè)計的齒輪和花鍵進(jìn)行了公差分析，同時介紹了截割部的安裝、維護(hù)和故障處理。本采煤機(jī)截割部具有較高的可靠性和安全維修性。
關(guān)鍵詞：滾筒式采煤機(jī)； 截割部； 行星齒輪傳動
ABSTRACT
This paper presents the development history, the composition and the principle of shearers in brief. On the foundation of analyzing the trade background of coal industry and mining equipment, look ahead the development of shearers, and according to the present development situation of shearers, we carried out the design of MG200/487-WD Shearer’s cutting unit.
This design firstly fixed on design scheme and selected basic components, and besides, developed the reliability analysis of transmission system. The design of MG200/487-WD Shearer’s cutting unit. It is made up of a gearbox and moderate breeze gear wheel transmission that the MG200/487-WD type mining machine cuts the cutting department, Cut the electrical machinery of cutting department and put to fix up horizontally in the rocker arm, The power that the motor outputs leans on a round of transmission of department of gear wheel and planet round via the tertiary straight tooth, Urge the cylinder to rotate finally. And gears and involute splines’ tolerances of geometrical quantity were analyzed. At the same time, introduced the installation, maintenance and fault disposal of this cutting unit. The cutting unit of MG200/487-WD Shearer has reliability and installation maintainability.
Keywords: shearer; the cutting unit; planetary gear drive
目 錄
1 概述 1
1.1引言 1
1.2我國采煤機(jī)30多年的發(fā)展進(jìn)程 1
1.2.1 20世紀(jì)70年代是我國綜合機(jī)械化采煤起步階段 1
1.2.2 20世紀(jì)80年代是我國采煤機(jī)發(fā)展的興旺時期 2
1.2.3 20世紀(jì)90年代至今是我國電牽引采煤機(jī)發(fā)展的時代 3
1.2.4 國際上電牽引采煤機(jī)的技術(shù)發(fā)展?fàn)顩r 4
1.3 國內(nèi)電牽引采煤機(jī)的發(fā)展?fàn)顩r 6
1.4 結(jié)構(gòu)特征與工作原理 7
1.4.1 搖臂 7
1.4.2 截割電動機(jī) 8
1.4.3 牽引部 9
2 總體方案的確定 12
2.1主要技術(shù)參數(shù)如下： 12
2.2傳動方案的確定 14
2.2.1 傳動比的確定 14
2.2.2傳動比的分配 14
3傳動系統(tǒng)的設(shè)計 15
3.1各級傳動轉(zhuǎn)速、功率、轉(zhuǎn)矩的確定 16
3.2齒輪設(shè)計及強(qiáng)度效核 17
3.3截割部行星機(jī)構(gòu)的設(shè)計計算 24
3.3.1齒輪材料熱處理工藝及制造工藝的選定 25
3.3.2確定各主要參數(shù) 25
3.3.3幾何尺寸計算 28
3.3.4.嚙合要素驗算 30
3.3.5齒輪強(qiáng)度驗算 31
3.4 軸的設(shè)計及強(qiáng)度效核 42
3.4.1選擇軸的材料 42
3.4.2軸徑的初步估算 42
3.4.3求作用在齒輪上的力 42
3.4.4軸的強(qiáng)度效核： 43
3.4.5安全系數(shù)效核計算 46
3.5 軸承的壽命校核 48
3.5.1對截Ⅲ軸的軸承22219c和Nj419進(jìn)行壽命計算 48
3.5.2行星輪軸承壽命的計算 49
3.6 花鍵的強(qiáng)度校核 50
3.6.1截Ⅳ軸花鍵校核 50
3.6.2行星輪系花鍵校核 50
4 采煤機(jī)的使用和維護(hù) 50
4.1潤滑及注油 51
4.2地面檢查與試運轉(zhuǎn) 51
4.2.1試運轉(zhuǎn)前的檢查： 51
4.2.2試運轉(zhuǎn)時檢查： 51
4.3下井及井下組裝 52
4.4采煤機(jī)的井下操作 52
4.4.1操作前的檢查： 52
4.4.2試運轉(zhuǎn)中注意事項： 52
4.5機(jī)器的維護(hù)與檢修 53
4.6采煤機(jī)軸承的維護(hù)及漏油的防治 54
4.7 硬齒面齒輪的疲勞失效及對策 56
4.8煤礦機(jī)械傳動齒輪失效的改進(jìn)途徑 59
4.8.1設(shè)計 59
4.8.2 選材 60
4.8.3 加工工藝 60
4.8.4 熱處理 61
4.8.5 表面強(qiáng)化處理 61
4.8.6 正確安裝運行 61
4.8.7 潤滑 62
5總結(jié) 63
參考文獻(xiàn) 64
英文原文 65
中文譯文 72
致 謝 77
中國礦業(yè)大學(xué)2008屆本科生畢業(yè)設(shè)計 第 12 頁
英文原文
THE SHEARER
Shearer
Longwall equipment consists of three major components: the hydraulically powered roof support, the chain conveyor, and the coal-cutting machine.
The two different types of coal-cutting equipment used in coal mines are shearers and plows.
Plows are used in low seams, 42in. or less. The unit consists of steel construction equipped with carbon-tipped bits. This passive steel unit is engaged to a guiding system on the face conveyor. An endless round link chain powered by synchronized electric drives on each end of the face conveyor pulls the plow body at speeds between 120 and 420 ft/min along the face.
For the cutting process the plow has to be forced against the coal face. This is done by hydraulic cylinder attached to the gob side of the face conveyor and to the base of the supports, or by a separate hydraulic prop. Forces of between 1and 3 tons are applied per cylinder.
A plow drive is attached to each drive frame of the face conveyor. Only 30% to 60% of the drive power supplied to the plow is used for cutting and loading of coal; the remainder is lost in friction. This means that the power loss is considerably higher than that of a shearer, which uses 75% to 85% of its power for the removal of the coal. As a result, rather large drives are required at the face ends.
Although there are many models, the shearer has several common basic components. A double-ended ranging-drum shearer (Fig. 8. 1), for example, consists of four major components: electric motors, gearheads, haulage unit (power pack), and cutting drums.
The electric motor ranging from 300 to 1000 horsepower (223~750kW) is the power source for the shearer. It provides power to run the hydraulic pumps in the haulage unit and the gearheads for the cutting drum. The large-capacity shearers are generally equipped with two electric motors: one for the haulage unit and one gearhead and the other for the other gearhead and other ancillary equipment. The motors can be remotely controlled.
There are two gearheads, one on the left-hand the other on the right-hand side of the shearer. Each gearherad consists of a gearhead gearbox and a ranging arm.
The cutting drum is laced with spiral vanes on with spiral vanes on which the cutting bits are mounted. Its diameter ranges from 34 to 72 in. (0.86~1.83 m) with rotational speeds from 30 to 105 rpm. The trends are toward fewer but larger bits and slower drum speed for better cutting efficiency and less coal dust production. The drums are also equipped with power cowls to increase the coal loading efficiency. The power cowl is usually located behind the cutting drum. For that reason, it can be rotated a full 180o.
The electric motor, haulage unit, and gearhead boxes combine to form the shearer’s body which is mounted on the underframe. The underframe has four sliding shoes. The face-side shoes are fitted and ride on the face-side top guide of the face conveyor pan, and the other two gob-side sliding shoes are fitted on a guide tube to prevent derailment. The tramming aped of the shearer ranges from 19 to 46 ft/min (5.8~14.0 m/min).
In addition, the shearer is equipped with auxiliary hydraulic pumps and control valves for operating the ranging arms and power cowls, water spraying devices, cable, chain anchorage and tensioners, and so on
In selecting the shearer, mining height should first be considered; that is, the diameter of the cutting drum, body height, length of the ranging arm, and swing angle must be properly selected. For the double-ended ranging-drum shearer, the maximum mining height cannot exceed twice the diameter of the cutting drum. The mining height can be determined by (Fig.8.3)
H=Hb-B/2+Lsinα+D/2
Where H=seam thickness or mining height
Hb=shearer’s body height
B=body depth
L=length of the ranging arm
α=the angle between the ranging arm and the horizontal line when the ranging arm is raised to its maximum height
D=diameter of the cutting drum
For example, for the Eichhoff EDW-170 L double ranging-drum shearer, Hb=4.3 ft, L=3.90 ft, α=52°，and D=5.3 ft. Its maximum cutting height is H=9.2 ft..
Types of modern shearers
Since its first appearance in 1954,the shearer has undergone continuous changes both in capability and structure. It is now the major cutting machine in longwall coal faces. There are two types of shearers, single-and double-drum. In the earlier models, the drum in the single-drum shearer is mounted on the shearer’s body and cannot be adjusted for height. Therefore it is not suitable for areas where there are constant changes in seam thickness and floor undulation. Thus the single-ended fixed-drum shearer is used mostly for thin seams.
Figure 6.10 shows a single-drum shearer with a ranging arm. The cutting drum is mounted at the very end of the ranging arm. The ranging arm can be raised up and down by hydraulic control to accommodate the changing seam thickness and floor undulation. But when the seam exceeds a certain thickness, the single-drum shearer cannot cut the entire seam height in one cut and a return cutting trip is necessary to complete a full web cut. Furthermore, since the drum is located on the headentry side, it generally requires a niche in the tailentry side. A niche is a precut face end, one web deep and a shearer’s length long. With a niche at the face end the shearer can turn around.
Nowadays, the double ranging-drum shearers are used predominantly. The shearer cuts the whole seam height in one trip. The two drums can be positioned to any required height (within the designed range) during cutting and lowered well below the floor level. The arrangement of the drums enables the whole seam to be cut in either direction of travel, thereby ensuring rapid face advance and shortening roof exposure time. There are various types of double ranging-drum shearers. Based on the location of the drums, there are two types: one with one drum mounted on each side of the shearer’s body and the other with both drums mounted on one side of the machine. The former type is the most widely used. Its advantage is that with one drum on each side of the shearer, it can sump in either direction. During the cutting trip, the leading drum cuts the upper 70% of the seam height while the rear drum cuts the lower 30% and cleans up the broken coal on the floor. The two drums are approximately 23~33 ft (7~10m) apart. When the shearer is traveling in the opposite direction to that of the face conveyor, the coal cut by the leading drum has to pass under the shearer’s body, which increases the moving resistance of the shearer and the face conveyor and could cause a “crowding” condition. If the broken coal is too large, it may block the shearer and stop the operation. In general, when the shearer and the face conveyor are traveling in the opposite directions, approximately 70% of the coal taken by the leading drum will pass under the shearer. But when they are traveling in the same direction, the coal taken down by the rear drum together with the float coal from the floor constitute the approximately 30% of the coal that has to pass under the shearer. The former case consumes 25% more power than the latter. As compared to the single-ended shearer, the underframe of the double-ended shearer is higher, thereby ensuring a sufficient cross section for coal passage.
Based on the method of adjusting the height of the cutting drum, there are also two types of shearers: ranging-arm shearer and gearhead shearer. The former one is commonly used, whereas the latter one is a recent development. The advantage of the gearhead shearer is that the haulage unit is located at the center of the shearer’s body and mounted on the underframe. On both sides of the haulage unit, there is a gearhead. Each gearhead contains an electric motor and a speed-reduction unit. The gearhead is raised and lowered by an adjustable hydraulic ram. The adjustable range of cutting height is large. It can reach up to 4.6 ft(1.4m).
Based on the mounting relation between the shearer and the face conveyor, there are also two types: the regular type which rides on the conveyor and the in-web shearer which moves on the floor in front of the conveyor. The in-web shearer is used mainly for the thin seams. As it moves along the face, the leading drum cuts the coal, making a sufficient space for the passage of the passage of the shearer’s body.
Haulage of the shearer
There are two types of shearer haulage: chain and chainless. These are discussed separately in the following paragraphs.
(1)Chain haulage
The haulage chain is a round-link chain which extends along the whole face width and is fixed on both ends at the head and tail drives of the face chain conveyor, respectively. The chain also passes through the driving and deflecting (or guiding) sprockets in the haulage unit of the shearer. As the driving sprocket rotates, its teeth trap to the matching chain links and move along the nonmoving haulage chain, thereby pulling the shearer along. When the driving sprocket rotates counterclockwise, the shearer moves to the right. Conversely, when the sprocket rotates clockwise, the shearer moves to the left. That part of the chain in front of the moving shearer is generally tight or on the tensioned side whereas the other side, behind the moving shearer, is slack or on the slack side.
The total resistance encountered by a cutting shearer consists mainly of the cutting resistance of the drum, coal loading resistance, and the frictional resistance between the conveyor and the shearer. The summation of the three types of resistance is the total haulage resistance of the shearer. The haulage unit must provide sufficient haulage power to overcome the total haulage resistance so that the shearer can move along smoothly. In Fig. 6.15 the tensile force in the tensioned side is P2 and that in the slack side is P1. Since the haulage force(P2) is the summation of P1 and P, if the chain on the slack side is completely slack, P1=0, then the tensile force in the tensioned side will be the required haulage force, P2=P. Under such conditions, although the chain is subjected to relatively small tension, the driving sprocket can not pass out the chain smoothly and may easily cause chain “stuck” or sudden tensioning of the chain. Thus in actual operation, the slack side normally maintains a small tension, i. e. , P2=P1+P. Only when the tensile force in the tensioned side is sufficient to overcome the total haulage resistance and the tensile force in the slack side, the shearer will be able to move.
When the shearer starts cutting from one end of the coal face, the haulage chain is relatively slack. As the shearer moves along, the chain is gradually tightened. When the shearer is near the other end of the coal face, the tensile force in the haulage chain is greatest. At this time the chain is most easily broken. In order that the tensile force on the tensioned side is not too high and that there is a sufficient tensile force on the slack side, most shearers are equipped with tension takeup systems. The tension takeup system is mounted at one end or both ends of the face conveyor depending on whether unidirectional or bidirectional cutting is employed. The haulage chain is connected to the tension takeup system. There are many types of tension takeup systems. But the basic principles are about the same.
The problems associated with chain haulage are chain sticking, chain breakage, and chain link tangling. They are due mainly to the fact that the haulage chain is lengthened and becomes loose after some periods of usage.
(2)Chainless haulage
In response to all the disadvantages associated with the chain haulage, the chainless haulage was developed. According to the haulage principles, the chainless haulage can be divided into three types: drive chain-rackatrack, drive wheel-rackatrack, and ram propulsion. The wheel-rackatrack haulage is the most popular type.
Figure 6.16 is a double-ended ranging-drum shearer equipped with the wheel-rackatracd haulage system. The haulage driving unit is similar to the conventional ones. The driving sprocket matches an idler sprocket, which in turn rides on the rail track made of steel peg rods. Thus, the driving system of power transmission is highly efficient. The rack is made of sections that have the same length as the conveyor pan, but they are installed in such a way that the center of each section is directly above the connection line between two adjacent pans. This will ensure maximum vertical and horizontal flexibility of the pans and keep the pitch deviation in the gap between two rack sections within admissible limits. Two methods are used to connect the line pans with the rack sections: one is to tie the rack sections to the sides of the line pans with screws and the other is to set the rack section on the sliding channel. Only the rack sections on both ends of the conveyor are fixed, so that a limited amount of flexibility in the conveyor direction is permitted. In Fig. 6.17 (b), the hook shape anchor on the rack section locks and slides on the guide tube of the line pans. This method is good for converting chain haulage to chainless haulage.
Figure 6.18 is another model of the wheel-rackatrack chainless haulage system. The driving sprocket is engaged directly to a special sprocket called Rollrack which has five hardened steel rollers spaced equally around the circumference. As the special sprocket or Rollrack rotates, the steel rollers engage on the teeth track of the rack and pull the shearer. Thus it is also called Roller-Teeth Rack chainless haulage.
中文譯文
采煤機(jī)
滾筒式采煤機(jī)
長壁工作面的設(shè)備包含三個主要部分：液壓支架，刮板運輸機(jī)和破碎機(jī)。
被用于煤礦的兩種不同類型的割煤設(shè)備是：滾筒式采煤機(jī)和刨煤機(jī)。
刨煤機(jī)被用于低煤層，42英寸或者更少。刨煤機(jī)由裝配滲碳刀尖的齒輪組成。這些鈍化的齒輪單元與工作面輸送機(jī)上的控制系統(tǒng)相連。由位于工作面輸送機(jī)兩端的同步電機(jī)驅(qū)動無級圓環(huán)鏈牽引刨煤機(jī)以每分鐘120至420英尺的速度沿工作面移動。
在切割進(jìn)程，刨煤機(jī)必須強(qiáng)迫對抗煤層表面。動力由裝在工作面運輸機(jī)底部的液壓油缸提供，每一個油缸提供1至3噸的動力。
工作中的刨煤機(jī) 并不是把全部的動力用來刨煤 ，只有30%到60%動力被用來切割和裝運煤；剩余部分在摩擦中消耗。這就意味著動力損耗要比滾筒式采煤機(jī)高。滾筒式采煤機(jī)動力的75%到85%用于割煤的。結(jié)果，要想獲得大功率采煤效果就不得在工作面機(jī)尾提供相當(dāng)大的動力。
雖然有許多部件，但是滾筒式采煤機(jī)有幾種基本部分。舉例來說，一臺雙滾筒可調(diào)高搖臂采煤機(jī)（圖8.1），由四個主要部分組成：電動馬達(dá)，機(jī)頭，牽引部分（電動機(jī)）和截割部。
圖8.1采煤機(jī)的組成
電動機(jī)為采煤機(jī)提供300到1000馬力的動力源，并且為牽引部的運轉(zhuǎn)的液壓泵提供動力和機(jī)頭服務(wù)于截割滾筒。大功率采煤機(jī)通常裝備兩臺電動機(jī)：一臺用于牽引部和一個機(jī)頭，另一臺用于另外一個機(jī)頭和其它輔助裝備，這些電動機(jī)是可以遠(yuǎn)距離操縱的。
這兩個機(jī)頭一個在采煤機(jī)的左邊，一個在采煤機(jī)的右邊，每個機(jī)頭都是由齒輪箱和搖臂組成。
截割滾筒的截齒安裝的是螺旋葉片，它的直徑范圍從34到72英寸（0.86～1.83m），回轉(zhuǎn)速度從30到105rpm。它的發(fā)展趨勢朝著少數(shù)但個大的且滾筒速度較低的截割效率比較好，并且可以減少粉塵的產(chǎn)生。滾筒之所以加擋煤板是為了增加煤的裝載效率，擋煤板通常安裝在截割滾筒的后面，由于這個原因，它可以旋轉(zhuǎn)180o。
電動機(jī)、牽引部和機(jī)頭箱組合成采煤機(jī)的機(jī)身安裝在底托架上，底托架有四個滑履，用在工作面的滑履是固定的，它騎在刮板輸送機(jī)溜槽工作面的頂?shù)儡壣?，另外兩個采空區(qū)滑履與道管配合是為避免出軌。采煤機(jī)的輸送速度范圍在19～46ft/min（5.8～14.0m/min）。
此外，采煤機(jī)的裝備還有輔助液壓泵、可操作搖臂的控制閥、擋煤板、噴水裝置、電纜、鏈條、錨固和張緊裝置等等。
在選擇采煤機(jī)時，采煤高度應(yīng)是首先被考慮的因素；那是因為，滾筒直徑，主體高度，搖臂長度，和搖擺角度都必須選擇適當(dāng)。對于雙滾筒可調(diào)高搖臂采煤機(jī)，最大的采煤高度不能超過滾筒直徑的兩倍。采煤高度可以通過（圖8.3）來決定
H=Hb-B/2+Lsinα+D/2
其中 H=煤層厚度或者采煤高度
Hb=采煤機(jī)主體高度
B=主體深度
L=搖臂長度
α=當(dāng)搖臂升高到它的最大高度時搖臂和水平線之間的角度
D=滾筒直徑
圖8.3采煤機(jī)采高
舉例來說，對于 EDW-170L雙滾筒可調(diào)高搖臂采煤機(jī)，Hb=4.3英尺, L=3.90英尺, α=52°，D=5.3英尺。它的最大截割高度為H=9.2英尺。
現(xiàn)代采煤機(jī)的種類
采煤機(jī)在1954年誕生的，在性能和構(gòu)造上經(jīng)歷了連續(xù)的變化。它主要應(yīng)用在走向長壁采煤工作面上。采煤機(jī)有兩種類型，包括單滾筒采煤機(jī)和雙滾筒采煤機(jī)。在早期使用的采煤機(jī)中，單滾筒采煤機(jī)的滾筒是在采煤機(jī)的軀干上，并且不能調(diào)高，所以不適合用于煤層厚度和水平波動大的區(qū)域，因此單滾筒采煤機(jī)主要適用于薄煤層。
圖6.10中顯示單滾筒采煤機(jī)的搖臂范圍，截割滾筒處于搖臂的最末端，搖臂通過液壓控制能夠升起和下降，可用在煤層厚度和水平波動大的區(qū)域。但是當(dāng)煤層超過某一厚度時，單滾筒采煤機(jī)就不能一次切割全部的厚度，需要回來再切一次才能完成全部工作。此外，因為滾筒位于采煤機(jī)側(cè)面，它通常要求放在采煤機(jī)一適當(dāng)?shù)膫?cè)面，這一適當(dāng)?shù)奈恢迷谇懈罟ぷ髅娴哪┒?，要有合適的深度和長度，采煤機(jī)可以在這個位置掉轉(zhuǎn)方向。
現(xiàn)今，雙滾筒采煤機(jī)使用很廣泛，它可以切割整個煤層厚度。在切割和下降到最低位置期間，兩個滾筒的位置可以按照規(guī)定的要求調(diào)整高度（設(shè)計范圍之內(nèi)）。滾筒的布置能夠切割整個煤層厚度和移動方向，從而保護(hù)工作面快速推進(jìn)和縮短頂板暴露時間。雙滾筒采煤機(jī)有各種型式，根據(jù)滾筒的位置可分為兩種類型：一種是兩個滾筒在采煤機(jī)的兩側(cè)，另一種是同時都在采煤機(jī)的一側(cè)。前一類型使用很廣泛，它的優(yōu)點是在滾筒的兩側(cè)割煤，可以在任一方向上。在切割時，上面的滾筒切煤層厚度的70％，下面的滾筒切煤層厚度的30％和清理頂板的碎煤。兩滾筒距離大約有23～33ft(7~10m)，當(dāng)采煤機(jī)平移反向到工作面運輸機(jī)時，滾筒截煤不得不在采煤機(jī)的下面，是采煤機(jī)增加移動的阻力和工作面輸送機(jī)和狀態(tài)條件。如果掉落的煤也是巨大的，它可以阻塞采煤機(jī)讓采煤機(jī)停止工作。通常采煤機(jī)和運輸機(jī)移動是相向的，大約采煤機(jī)的滾筒可傳遞給輸送機(jī)70％的煤，但是當(dāng)它們平移方向相同時，由滾筒切下的煤30％傳遞不到輸送機(jī)上，前者比后者消耗25％的功率。同時比較，單滾筒采煤機(jī)比雙滾筒采煤機(jī)底架較高，從而確保了充分的煤的橫截面通道。
采煤機(jī)根據(jù)切割滾筒的調(diào)整高度還可分為兩種類型：搖臂采煤機(jī)和機(jī)頭采煤機(jī)，前一種是普遍使用的，而后者是近期發(fā)展出來的，機(jī)頭采煤機(jī)是牽引部位于采煤機(jī)機(jī)身的中心和底架的上面。在牽引部的兩側(cè)各有一個機(jī)頭，每個機(jī)頭都包含一個電動機(jī)和一變速裝置。機(jī)頭由一可調(diào)整液壓控制它的上升和下降。它的割煤高度的調(diào)節(jié)范圍很大，可以擴(kuò)展到4.6ft(1.4m)。
根據(jù)采煤機(jī)和輸送機(jī)的安裝位置分為兩種類型：標(biāo)準(zhǔn)的是騎在輸送機(jī)上面，另一個非標(biāo)準(zhǔn)的是安裝在輸送機(jī)前面的，非標(biāo)準(zhǔn)采煤機(jī)主要使用在薄煤層中，當(dāng)它在工作面向前移動時，引導(dǎo)滾筒割煤，讓出足夠空間用于采煤機(jī)的機(jī)身通過。
牽引采煤機(jī)
牽引采煤機(jī)分為兩種類型：有鏈牽引和無鏈牽引，下面就對這種類型進(jìn)行論述。
(1)鏈牽引
牽引鏈?zhǔn)且环N整體齒寬伸展向前的圓環(huán)鏈，是決定鏈?zhǔn)綘恳斔蜋C(jī)工作面的兩端的操作。采煤機(jī)牽引部的鏈可以推動和轉(zhuǎn)向（或定向）鏈輪。當(dāng)傳動鏈輪旋轉(zhuǎn)時，通過牽引鏈與主動鏈輪相互嚙合向前移動，從而驅(qū)動采煤機(jī)向前移動。當(dāng)傳動鏈輪逆時針旋轉(zhuǎn)時，采煤機(jī)向右移動，反之，當(dāng)鏈輪順時針方向旋轉(zhuǎn)時，采煤機(jī)向左移動。采煤機(jī)移動時，前面部分的鏈通常是拉緊或這一側(cè)張緊，在采煤機(jī)的后面則是松弛或一側(cè)松弛。
總的阻力等于采煤機(jī)滾筒切削力、煤的負(fù)載阻力、運輸機(jī)與采煤機(jī)之間的摩擦阻力的總和，這三種阻力之和就是采煤機(jī)的牽引力。牽引部必須提供足夠的牽引功率以克服總牽引阻力，以便采煤機(jī)能夠平穩(wěn)的向前移動，在圖6.15中，在拉緊裝置的一側(cè)拉力是P2，在松弛的一側(cè)是P1，因為牽引力P2是P1與P的總和，如果在鏈條松弛的一側(cè)是完全松弛的，P1＝0，在張緊的一側(cè)的拉力就是需要的牽引力，這時P2＝P。在上述條件下，雖然鏈條受到相對較小的拉力，傳動鏈輪不能平穩(wěn)通過，可能容易引起鏈條阻塞或突然拉緊鏈條。因此，在實際操作中，松弛的一側(cè)要正常保持一個較小的拉力，P2＝P1＋P。只有當(dāng)拉緊裝置的一側(cè)的拉力足夠克服總的牽引阻力和在松弛一側(cè)的拉時，采煤機(jī)才能移動。
當(dāng)采煤機(jī)從采煤工作面的一端開始工作時，牽引鏈相對是松弛的，當(dāng)采煤機(jī)向前移動時，鏈逐漸的繃緊，當(dāng)采煤機(jī)到工作面的另一端時，牽引鏈的張緊力是最大的，這時牽引鏈最容易斷裂。為了使張緊力不致過高，并且使松弛部分有足夠的張力，大多采煤機(jī)裝有拉緊裝置，拉緊裝置安裝在工作面輸送機(jī)的一端或兩端，這取決于單向還是雙向切割，牽引鏈通常和拉緊裝置關(guān)聯(lián)的，包括許多種拉緊裝置，但它們的基本性能是一樣的。
與鏈牽引有關(guān)的問題有鏈阻塞、鏈斷裂、鏈纏結(jié)，這些都是主要的事實，使用一段時期后牽引鏈會拉長和變得松弛。
（2）無鏈牽引
與鏈牽引的不利因素相比，鏈牽引是有所發(fā)展的。按照牽引原則，無鏈牽引可分為三種類型：鏈軌式無鏈牽引，齒軌式無鏈牽引，銷軌式無鏈牽引，齒軌式無鏈牽引是使用最為普遍的。
圖6.16是齒軌式無鏈牽引雙滾筒采煤機(jī)設(shè)備，牽引裝置是最普遍的一種，傳動鏈輪與皮帶鏈輪相嚙合，依次安裝在鋼制的導(dǎo)軌上，因此，驅(qū)動系統(tǒng)的動力傳動裝置的效率是很高的。導(dǎo)軌由許多零件組成與運輸機(jī)底座一樣的長度，但是它們安裝在各個零件的相鄰底座中心線上，這樣就能保證底座垂直和水平撓性達(dá)到最大值，保持在兩機(jī)架齒距偏差范圍在許用極限。習(xí)慣上有兩種方法可連接底座與機(jī)架部分：一種是將機(jī)架部分到底座線側(cè)面用螺旋桿連接在一起，另一種是將機(jī)架部分裝配到溜槽上。只有運輸機(jī)兩端的機(jī)架部分是安裝上去的，以便運輸機(jī)操縱的極少的撓性達(dá)到許用值，在圖6.17（b）中，吊鉤固定在導(dǎo)軌的鏈節(jié)和底座線導(dǎo)向葉片的滑道上，這些方法適用于鏈牽引到無鏈牽引的的轉(zhuǎn)換。
圖6.18是另一種齒軌式無鏈牽引裝置，傳動鏈輪與一特殊的滾子鏈輪直接嚙合在一起，它有五個淬火鋼滾輪，均勻的分布在一圓周上。當(dāng)這一特殊的鏈輪或是滾子鏈輪旋轉(zhuǎn)時，淬火滾子在導(dǎo)軌的齒軌上運行并牽引采煤機(jī)運動。