Mechanisms and Kinematics of Hydraulic Support for Top-Coal Caving

Dec.2001Journal of China University of Mining & TechnologVol 11 No. 2Mechanisms and Kinematics ofHydraulic Support for Top-Coal CavingDONG Zhi-feng(董志峰), WANG Show-feng(王壽峰),CHANG Hong(常宏), wUJian(吳建)2I. Department of Mechanical and Electronic Engineering, CUMT. Beijing, 100083, P. R. China2. Department of Resource Exploitation Engineering, CUMT, Beijing, 100083, P. R. ChinaAbstract: The structure and characteristic of new type of hydraulic support for top-coal caving were discussed. The mechanism and kinematics of the hydraulic support were analyzed. The formulas were deduced to calculate the velocity and acceleration of top beam, shield beam, front and back legs, whichgive the solution to the design and research for hydraulic support.Key words: top-coal caving; hydraul ic support; mechanisms; kinematicsCLC number: TD 355+ 41 Document code: a Article ID: 1006-1266(2001)02-0155-041 Introductiontop beam form the closed roofunlaceIntegrated mechanized top-coal caving is a coal of the front legs inclining forward slightly are conmining method in longwall where the machine and nected with the middle of the top beam. The topequipment such as shearer, conveyors and hydraulicnd hydraulic ends of the back legs are connected with the frontsupports are highly integrated and mining and cav- part of shield beam. The cylinders of the back legsing are carried on concurrently. The great achieve- can not only provide push force to support the roofments in this field of our country are well known in load, but also provide pull force to balance the topthe whole world. However, hydraulic supports, beam. All of bottom ends of the legs are connectedthe most important machines in top-coal caving, arewith the base. The base has a structure like chairIsually heavy in weight, large in scale and compli- back connected with the shield beam. One end ofcated in structure, It is difficult to move them and the shield beam is connected with top beam, and theto assemble or disassemble them. So it is not suitable other end is connected with the rear beam in whichfor coal mine where the geological conditions are not is an opening board. Both rear beam and openingvery good.3. In order to solve this problem, a newboard are driven and controlled by cylindertype of hydraulic support for top-coal caving was de- adjust the caving coal to move. Under the reareloped This hydraulic support is light in weightompact in size, high in load capacit2 Characteristic of the New Support2. 1 Structure of the hydraulic supportThe hydraulic support, as shown in Fig. 1mainly composed of top beam 2. front beam 1中國煤化工shield beam 5, base 6, rear beam 8, cylinder 7CNMHG hvdraulic supporte top1. Front beam; 2. Top beam: 3. Front legs:4. Back legs; 5. Shiled beam: 6. Base;and front beam which can stretch out and backCylinder; 8. Rear beam: 9. Opening boardReceiveda數據-05-08Biography DONG Zhi-feng(1975-) male, from Anhui Province, associate professor156Journal of China University of mining & TechnologyVol. 11 No. 2beam is the back conveyor. Two cylinders drive themovements of the support and the conveyors.2.2 Features and characteristics1) The concurrent stretching out and back ofcan prevent the front coal roof from2) The two planes at different angles on theshield beam make the top-coal move down and becrashed slowly, and prevent the coal and the rockFig 2 Mechanisms of the hydraulic supportfrom being mixed. Therefore, the good quality ofcoal can be minedn(H-d.cos 8-do3)The double function(push and pull) of backleg's cylinders provides a good loading capacity andB=i(H-h,-d cos 0)the position balance of the top beam(2)4)The base and shield beam are hinged directsin d=lsin a-lsinφ+d-h1)ly, which increases the strength of the structure tobear the deviant load and to work with inclinationsin a,=Th-db+l,sin(b-0)]5)There is a large space in back of the chair on In AO,BO,, therethe basemen for conveyer to move caving coal1=√l+B-2l0(-a+B),(3)hich provides a bigger space and a higher heightthan that of other supports for caving coalA,=l(h-dr-d sin 8)2+6) The strucuture of the support provides(l4cos0+l1cos中-S1-S2)2]2,(4)horizontal force to maintain the roof in good condirotanh,-dbtion as the roof moves down gradually.The path equation of C on top beam is7) The support can be moved conveniently because it is light in weight, small in size and compactxc=s+s2+lcos(6)ye=dr+ lsin afIn structure.3. 2 Kinematics analysis8) The low position of caving coal opening deFrom(1)we get the first derivative with respcreases the dust and improves the working environto time tdll, sin gl sin b3 Kinematics of the Hydraulic Supportdo3. 1 Mechanism anal ysislesin aThe main mechanisms of the support is consistsof base, front legs, back legs, top beam and shieldd i lcos bbeam, which can be simplified as a plalcos a dtnism with 5 rods, 6 revolute pairs and 2 sliding(7)dφdlbpairs. The base is frame with Or, O, and O,(Figl2sin(中-.)2)中國煤化工From Fig. 2, we haveCNMHGL, cos f+ L,cos 0=S+S,+ lcos arl2cos(中-6。)l sing+h+ lsin b= dr+ lisin arl2cos(中-日)-l1cosa=Sll2siy數據+h1= L sin ab+dEg (7) can be expressed as matrixDONG Zhi-feng et almechanisms and Kinematics of Hydraulic Supportdldi cos al dtdedl,l1cosφl(shuí), cos 6(8)l2sin(∮-6)0 l,sin adlbl2cos(中-0n)lcos ahdd ewe get the solutiondldtl2sin(a-中+6n)dtdll1sin(ax1-中)dlL, sin (a-o)Ldt L, sin(ab-4+0,)dt(9)dt0)dtLl sin(a-0)LL2sin(ar -.) dt+ cos(a-8dodt=0, since L, cos B=Sd2l-L, d dpsd edl,/dtA,sin(ar-p)sino da dl odlb/dtl2sin(a1-小-n)d2l,Formula (10) is that front and back legs mustlsin yd cfollow, in order that the top beam moves up andown horizontally.2cos anda dl+l sin al\ dtFrom(1) we get the second derivative withdtl2cos(中-B.)d20-lsin 8.5+dhi.cos adCt= sin a dr2-lasin(s-o) dicOSdah dlb2cos adear(11)+C2=0,d2gBasin (s-Ba) dzd2 abdt2+C3=d p-iad2+4/ca/2d 2acos(-B)2中0d2+C=0.SInaiEg (11)can be expressed as matrixd 2a1-A21d2L cos gALl dt2dtl2sin(一n)Lhsio rda中國煤化工dtd tCNMHGsin(a-o)Ldd158Journal of China University of mining & TechnologyVol. 11 No. 2dlbsin2& dl. daydt dtd20dare cos (a-8)d28d2L,dtz l sin(apL,l,Asin(a-6dl, d esin(a-8)dtdtl2l,Asin(a-o)L??b/da,l sin(ar+8)dlbl2√1-ABecause the top-coal caving supports must bd tcoordinated into the shearer, front and back con-where, A= sin(ab-4+0)veyors, the dimensions, positions and movements ofIf the cylinder's velocities of the front and backthe equipment are essential to coal productionlegs are constant, that isd2L pdeLu4 Conclusions1) The new top-coal caving support must besatisfied with certain relationshipyd2小LAdas i sin 2ab dt dtdl daand motion so that it can work perfectly and effectively and avoid interference and failure√1-A2d2)The deduced formula and equations are thedfoundations of research and design for the top-cavdtbal 2 di+2cos a, in(g-0 ) dt dting supports. They are also the tools for productionand operation3) In order to keep top beam in horizontal, thed 2alcos(ar-8) decylinders of front and back legs must be satisfied the=-sn(a4-0)(d)+sn(a=0)formula (10) when they go up and down. In thiscos(9-0)case, the traces of any points on the top beam arecles with the radius being the distance fromhiof shield beam and top beam to hinges ofl sin(ar-0) dtshield bean and basedar dln(中-)l, dt dt L,Asin(a-0)L"b dtReference1吳健.綜放開(kāi)采技術(shù)15年回顧[].礦山壓力與頂板管理,1998,(增刊):1-[2]楊振復,羅恩波.放頂煤開(kāi)采技術(shù)與放頂煤液壓支架[M].北京:煤炭工業(yè)出版社.1995.73]王國法.液壓支架技術(shù)[M].北京:煤炭工業(yè)出版社.1999.9中國煤化工CNMHG