【机械类文献翻译】采煤机

英文原文THE SHEARERShearerLongwall 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 1and3 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 underfr ame 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 sprayingdevices, cable, chain anchorage and tensioners, and so onIn 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/2Where H=seam thickness or mining heightHb=shearer’s body heightB=body depthL=length of the ranging armα=the angle between the ranging arm and the horizontal line when the ranging arm is raised to its maximum heightD=diameter of the cutting drumFor 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 shearersSince 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 forcoal 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 shearerThere are two types of shearer haulage: chain and chainless. These are discussed separately in the following paragraphs.(1)Chain haulageThe 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 unitmust 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 haulageIn 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 theconventional 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.中文译文采煤机滚筒式采煤机长壁工作面的设备包含三个主要部分：液压支架，刮板运输机和破碎机。