振动筛毕业论文外文文献翻译分析解析

1、Dynamics and screening characteristics ofa vibrating screen with variable elliptical traceHE Xiao-mei,LIU Chu-she ngSchool of Mechanical and ElectricalEngineering,ChinaUniversityof Mining &Tech no logy,Xuzhou,Jia ngsu 221116,Chi naAbstract : the ideal motion characteristics for the vibratingscreen w

2、as presented ,vibrati ng scree n with variable elliptical trace was proposed. An accurate mecha ni cal model was con structed accordi ng to the required structural moti on features.Appl ying multi-degree-of-freedom vibrati on theory,characteristics of the vibrati ng scree n was an alyzed.K in ematic

3、sparameters of the vibrati ng scree n which moti on traces werelinear,circularor ellipticalwere obtained.The stable solutions of the dynamic equationsgave the motions of the vibratingscreen by meansof computer simulations.Technologicalparameters,i nclud ing amplitude,moveme nt velocity and throw ing

4、 in dex,of five specific points along the screen surface were gained by theoretical calculation .The results show that the traces of the newdesigned vibrating screen follow the ideal screening motion .The scree ning efficie ncy and process ing capacity may thus be effectively improved.Keywords：varia

5、ble elliptical trace;screening process with constant bed thickness; dyn amic model;moti on characteristic;scree ning characteristics1 In troducti onScree ning operati ons are an importa nt part of coal process ing. The vibrati ng scree n is one of the most exte nsively used scree ning tools. Vibrat

6、ing scree ns, such as linear vibratingscreen, circular vibratingscreen or ellipticalvibratingscreen, havea simple translationalmotion. The motion follows the same path everywhere on the screenand so the screen has constant transport velocity and throwing index, which leads to low screening efficienc

7、y. Augmenting the throwing index to improve breaks the exciting motors process ing capacity lowers the work ing.In this paper , wereport on the design of a new vibrating screen with variable motion traces that is based on the prin ciple of scree ning process with con sta nt bed thick ness 3 4.Differ

8、ent parts of the vibrating screen traverse different ellipticaltraces andthe result ing moti on agrees well with the ideal moti on .Thus the scree n process ing capacity and efficie ncy can both be improved.2 Ideal motion for a screen surface and the proposal of a vibratingscreenwith variable ellipt

9、ical trace2.1 Scree ning characteristics of com mon vibrat ing scree nsVibrat ing scree ns com monly work at a fixed vibrati on inten sity.Material on the scree nsurface moves by throwi ng, rolli ng or slidi ng moti ons .For com mon scree ners ,material granularity is widely distributed at the feed

10、end .The energy imparted to the material particles from the vibratingscreen is severely dissipated .Consequently ,a large numberof particles become lam inated only a short distanee from the feed end .The materialpenetrates the screen within the first 1/4 to 1/2 of the screen ,which affects screening

11、 and lowers processing capacity 5.The decrease of fine-grained material causes the ratio of particles close in size to ,or larger tha n ,the mesh to in crease .Thus ,the scree ning efficie ncydecli nesdramatically .The materialgranu laritysimulta neously becomesuniform and the energy imparted from t

12、he vibrations to the material suffers littleloss .He nee ,the amplitude and velocity of the material particlesin crease .This causesthe material bed depth at the feed end to be thick while at the discharge end it isFig. 1 Screening characteristics of a coiimion vibrating screen1=im CHUErur1C氏；p s dI

13、VIIS meen surface 1 engtliThin .This kind of motion leads to an asymmetrical penetration along the screen surface,which in flue nces the scree ning efficie ncy and process ing capability 6.Com mon screening characteristics are shown in Fig.1.2.2 Ideal moti on for scree n surface and impleme nting sc

14、hemeThe ideal motion for screen surface is described below, according to the principleof screening process with constant bed thickness .The feed end of the screen has a bigger throwing index and a higher material delivery velocity ,which makesbulk material quickly pen etrate and causes rapid delam i

15、n at ing. Earlier lam in ati on of material in creases theprobability of fine-grained material passing through the mesh .The screen has an appropriate throwing index and a little higher material delivery velocity in its middle part .This is of ben efit for stabiliz ing fin e-gra ined materials and f

16、or pen etrat inguniformly along the screen length .A lower throwing index and material delivery velocityn ear the discharge end causes the material to stay Ion ger on the scree n and en couragesmore complete penetration of the mesh. Twomethods are currentlyused to improve screeningefficie ncy 7 8.Th

17、e first is to add material to the scree n from multiple feed ports.This is troublesome in practical use especially in terms of con troll ingthe distributio nof differe ntly granu lated materials .He nee it is rarely used in practical producti on.The second way is to adopt new screening equipment lik

18、e, for example, a constant thickness scree n. The moti on of the new scree n surface causes material to main ta in the same, or an in creased, thick ness .It achieves a rather more ideal moti on.The main problem with the con sta nt thick ness scree n is that it covers a bigger areaand that the struc

19、ture is complicated and hard to maintain .A simple structure with good scree ning efficie ncy isstill an ecessity. We have desig ned a new vibrati on scree n witha variable elliptical trace that is based upon an ideal screen motion for use in raw coal classification. The size of the vibrating screen

20、 is 3.6mx 7.5 m,the feed granularityis 0 to 50 mm and the classificati on granu larity is 6mm.Elliptically vibrat ing scree nscomb ine the basic adva ntages of both circular and lin ear vibrat ing scree ns 9 10.Thelong axis of the ellipse determ ines material delivery and the short axis in flue nces

21、 material loose ning, to be exact.3 Dyn amics model an alysis of vibrati ng scree n with variable ellipticaltraceWemadethe excitingforce deviate from the center of gravity,tochange the motionpattern of the new vibrat ing scree n. The stiff ness matrix of the vibrati on isolati on spri ng was not zer

22、o un der these circumsta nces and the vibrati ng system had multiple degrees of freedom .Minor tran sverse wagg ing was n eglected to simplifytheresearch.The moti on was con sidered to be a lin ear vibrati on of a rigid beam in theIon gitud in ally symmetrical pla ne.At each point the vibratio n is

23、a comb in ati on of the tran slati on of the cen ter of gravity and the scree n pitchi ng about the cen ter ofgravity.Previous studies n eglected the in flue nee of elastic forces in the horiz on taland verticaldirecti onon the swi ng of the vibrat ingscree n 3,11.A n accurate dyn amicmodel con sist

24、 ing of three differe ntial equati ons that in clude coupli ng of degreesof freedom in the vertical,horiz on tal and swing directi ons is proposed.Fig. 2 Matiieinaticsil model of vibrating screenThe mathematical model of the vibrating screen is shown in Fig.2.The center ofgravity, is take n as the o

25、rigi n of a recta ngular coord in ate system at staticequilibrium,in accordanee with rigid motion on the plane 12.Simultaneousdiffere ntialequati ons in gen eralized coord in ates using cen ter of gravitycoordinates,(x,y),and the swing declination angle,0 ,may be written as - . (1)p) -ffi- X; sin 璇右

26、 + 厶)x一化coso(厶一右)7- 皿璇右? +厶，)&where M is the mass of the vibrating screen s the moment of inertia of M relativeto the center of gravity,O;x and y the displacements in the x and yOdirectionas;x and y the velocities in the x and y directions and y the accelerations in the xand y direct ions; is the sw

27、ing an gular displaceme nt;a the in stallati on an gle;fx,fyond father damp ing coefficie nts in the x,y and directi ons;x k and k the stiffness coefficie nts of the support ing spri ng along the x and ydirect ions; AO the amplitude of the excit ing force, give n by2 0 A =mr3 , where r isthe radius

28、of eccentricity the mass of the eccentric block and the exciting angularfreque ncy; L1 and L2 the dista nces betwee n each support ing spri ng and the cen ter ofgravity s the distaneebetween the rotating center of the eccentric block and thecen ter of gravity; and, B the in cluded an gle betwee n th

29、e l and x direct ions. The damp ing force is rather small and can be neglected. Then Eq. (1) can be simplified to Eq.(2).2Xf(x- 4)costc?/Mv + 2k v= sin- JO + & sin of (厶 + 厶) cos a(厶厶)y十 ky cos a(厶+ L： )0 = - A/sin(a)f - P)4 Motion and screening effect analysis of a vibratingscreen with variableelli

30、ptical trace4.1 An alysis of the moti on parameters Multiple degree-of-freedom vibratio n theorywas used to find a stable solution for the forced vibration 13,as follows:I x = X cos cott+ r + C2 ”/ 二(ES + CHY(6)Whe n E 2 S 2 +C 2 H 2 +2 ESCH=0, the trace of poi nt D is a line. Whe n E =Sa nd C =H, t

31、he trace of point D is a circle. In general. (6) expresses the equation of an ellipse.The xoy coord in ate was rotated 丫 degrees an ticlockwise to give a new set of x oycoord in ates. A sta ndard elliptical equati on was the n obta ined after elim in ati ng D D xy in Eq.(7).ES+CHf(S2 + /2)cos2 / + 2

32、(5(7- EH)sin7 cos/ + E1 + C2)siir /lr =QES+CHf(5? + Z/?) sin2 y - 2(SC - EH) sin / cos y + (E2 + C2) cos2 71arctan2SC-EH)(屮+胪)_ (于+厂)From this we know that some points on the screen move in a line or a circle whileothers move in an ellipse .As long as the relative position of the rotating center of

33、the ecce ntric block and the cen ter of gravity are properly adjusted, variableelliptical moti on of the scree n will be obta ined .This provides a reas on able throw ing in dex and material delivery velocity and improves scree ning efficie ncy.4.2 An alysis of motio n trace and scree ning efficie n

34、cyThe stable solutio n of a vibrat ing system, in terms of the vibrati ng scree n, canbe give n byThe equati ons of moti on for any point on the vibrati ng scree n arei = -0,00368cosrEq.(8)shows that the cen ter of gravity traces an approximate circle and that theamplitude in the horiz on tal and ve

35、rtical direct ions is betwee n 3.5 mmand 5 mm.Fig.3shows how the cen ter of gravity moves in three degrees of freedom.Fig.3 gives thean gular phase differe nee betwee n the horiz on tal and vertical direct ions as well as the amplitude of the swing an gle.40 D.l D.20.3D.4/(s)(a) Ml oh on in the 找 di

36、rectionD D.l 0.2 Q.3 DJ心(b) Motion in the v dbrectionFig. 3 Movement of the scixen coiter of 書 nrvity in tlirce degree; of Reedcm(c) Motion efthe swing angle 厅5 Con clusi onsaccording to the principle of screening process with constant bed thickness.Different poi nts on the vibrat ing scree n trace

37、differe nt elliptical paths.The moti on pattern agrees well with the ideal motion characteristicfor a screeningsurface.Thus,scree ning capacity and process efficie ncy can be in creased.2) A theoretical kin ematic an alysis of the vibrati ng scree n was done to study howvarying different parameters

38、affects the motion of the screen.Kinematicsparametersof the vibrat ing scree n that moti on traces are lin ear,circular or elliptical are obta in ed.3) Motion traces of totalvibratingscreen were gained through computersimulatio ns.Scree ning tech no logical parameters,i ncludi ng amplitude, velocity

39、 andthrowing index,of five specific points along the screen surface were calculated. These parameters are related to scree ning efficie ncy. The results show that the moti on patter n of the desig ned vibrat ing scree n con forms to an ideal scree ning moti on and that the desig n is able to effecti

40、vely improve scree ning efficie ncy.4) The positi on of the exciter axle cen ter,relative to the cen ter of gravity of the vibrati ng scree n,is extremely importa nt for scree ning efficie nt.Thus,we can desig n a vibrati ng scree n with higher process ing capacity without in creas ing power con sum

41、pti on by adjusti ng the relative positi on of the axle cen ter.This is a point that requires further study.Refere nces1 We n B C, Liu F Q.Theory and Applicatio n of Vibratio n Machi nes.Beiji ng:Chi naMachi ne Press,1982.2 Gu Q B,Zha ng E G.Study on complex-locus vibrati on scree n. Mi ning&Process

42、i ng Equipment,1998(1):42 - 46.3 Hao F Y.Coal Preparati on Manu al:Tech no logy and Equipme nt.Beiji ng:Chi na CoalIn dustry Publishi ng House,1993.4 Yan F.Screening Machines.Beijing:ChinaCoal Indus-tryPublishing House,1995.5 Liu C S,Zhao Y M.Study on non li near characteristics of si ngle particle

43、onscreening surface.Mining&Processing Equipment,1999(1):45- 486 Tao Y J,Luo Z F,Zhao Y M.Experimental research on desulfurization of fine coalusing an enhan ced cen tri- fugal gravity separator.Jour nal of China Uni versity ofMining&Technology,2006,16(4):399- 403.7 Zha ng E G.Scree nin g,Crushi ng a

44、nd Dewateri ng Equipme nts. Beiji ng: Chi na CoalIn dustry Publishi ng House,1991.8 Khoury D L.Coal Clea ning Tech nology .USA:Noyes Data Corporati on ,1981.9 Shang N X,Na J F.2TYA1842 elliptical vibration screen.Mining&ProcessingEquipment,1990(2):20 - 24.10 YeHD.EIIipticalisopachous scree ning tech

45、 no logy an dits applicati on.Sin teri ngand Palletizing,1999,5(3):30- 33.11 Wen B C,Liu S Y,He Q.Theory and Dynamic Design Method of VibrationMachi nes.Beiji ng:Chi na Machi ne Press,2001.12Wa ng F,Wa ng H.Scree ningMachi nes.Beiji ng:Chi na Mach ine Press,2001.13 Ni Z H.Vibration Mechanics.Xi an:X

46、i an Jiaotong University Press,1989.14 Zhu W B.Worki ng prin ciple and computer simulatio n of vibrat ing scree n withcomplicated motion trace.Mining &Processing Equipment,2004(10):34- 36.15 PederM.The moge nsen E-series a new scree ningon cept.M in eralProcessing,1996,7(37):311- 315.16 We n B C.S y

47、n chro nizatio n theory of self-s ynchronous vibrat ing mach ines withellipse moti on locus. Bost on:America n Society of Mecha ni cal Engin eers,1987:495 - 500.变椭圆轨迹振动筛的动力学和筛选特性何小梅，刘楚生机械和电气工程学院，中国矿业大学科技，江苏省徐州市221116,中国摘要：根据振动筛的理想运动特性，提出了变椭圆轨迹的振动筛。根据所需的结构运动特性建立了一个精确的力学模型。应用多自由度振动理论，对振动筛的特性进行了分析。获得了线

48、性的、 圆形或椭圆形的运动轨迹振动筛的运动学参数。通过计算机模拟振动筛的运动动态方程得以有效 的求解。通过理论计算求得振动筛上五个具体点的工艺参数，包括振幅、运动速度和抛掷指数。结 果显示，新设计的振动筛的轨迹遵循理想的筛选运动。筛分效率及处理能力可能因此而得到有效改进。关键字：变椭圆轨迹；等厚筛分；动态模型；运动特性；筛分特性1刖言筛分操作是一个重要的煤矿处理组成部分。振动筛是最广泛使用的筛选工具之一。振动筛， 如直线振动筛、圆振动筛或椭圆振动筛，都有一个简单的平移运动。运动在振动筛上到处都遵循 相同的路径，所以振动筛有恒定的运输速度和抛掷指数， 从而导致低的筛分效率。增强抛掷指数来 改善激

49、振电机在工作中的较低的处理能力。在本文中，我们就一个基于等厚筛分理论的新的可变的运动轨迹振动筛的设计做报告3 - 4 /- /7)4变椭圆轨迹振动筛的运动和筛选的效果分析4.1运动参数的分析运用多自由度振动理论来找到一个强迫振动的稳定解13，如下: x= Xcosa)tG) 卩二 Y sin a)r+ cos a)t6-0. sin + & cos cotIJL-mrarmraflkx - Max 2k y-Meo2w/w/cosp+ 仁cos/(厶一厶)FJ卅-k cos+ 厶？)-zff/w2/sin 0 +化sinat + L.XJa)2 一 Zrcosz(厶，+ 厶x/f = x+ 6

50、D - X cos (q sin cor& cos r) I) =q/? sin&y+ (A + &Z? )coeoyp = y QDx = Ysin - (q sin *v+ 仇 cos(Mf)Z?i =(F-qQJsinfty cosftr1xn - Ecos cot- C sill cotP(5)y/ - Ssin H cos cot心 H、；7QC-EH)佔+ (F + , = (ES+ CH$ (6)当E2S2 C2H2 2ESCH =0 , D点的轨迹是一条直线。当 E=S C=HS寸，D点的轨迹是圆。 一般来说，式（6）表示椭圆面在直角坐标系的方程。XOY坐标系以丫角速度逆时针旋转从而给定 一个新的坐标系xoy。在消除xDyD后可得一个标准的椭圆公式（7）。a =If =(ES+C/f)2(S- + /-)cos2 / + 2(SC