Pressure Field of Multi-pad Annular Recess Hydrostatic Thrust Bearing

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254 Journal of Donghua University(Eng．Ed．)VoL 30，No．3(2013)Pressure Field of M ulti—pad Annular Recess Hydrostatic Thrust BearingYU Xiao．dong(于晓东)h，MENG Xiu．1i(孟秀丽) ，LI Huan—huan(李欢欢) ，TAN Li(谭 力) ，WAN GZhi—qiang(王志强) ，ZHOU Qi—hui(周启慧) ，ZHUAN G Jian—xin(庄建新) ，YANG Lan(杨 岚)。

j School of Mechanical&Power Engineering，Ha~in University of Science and Technology，Harbin 150080，China2 Heilong]iang Polytechnic，Harbin 150007，China3 Qiqihar Heavy CNC Equipment Co．，Ltd．，Qiqihar161000，ChinaAbstraet：In orderto salvethe deformation ofthehydrostaticthrustbearing with multi-pad annular rece in the heavy computernamerical control(CNC)equipment．the simulation concerningpressure fidd of hydrostatic thrust bearing with multi．pad annularrece 憾 was carried out． finite volume method of computationalnuld dynamics(CFD)was used to compute the three-dimensionalpressure field of gap nuld between the rotary worktable and thebase．The influence of the rotational speed on the bearing pressureperforman cewss studiedbased on CFD an dlubricationtheory．andthe method revealed the presure distribution law． The resultsqualitatively agree well with the experimental data． The resultsindicate that the oil eavity pressure decreases gradually withrotational spe ed enhan cing．Th e reliability of a hydrostatic thrustbe aringwith multi-pad annular recess cAInbe predictedthroughthismethod 。an dthe optimal design of such products can be achieved。

an d the numerical simulation method ean provide reasonable dataf0r design。lubrication。experiment．an d deformation computationof hydrostaticthrustbearinginthe heavy CNC equlpinent.

Key words： multi-pad annular recess： hydrostatic thrust bearing：pressurefield；experimental assessmentCLC number：TH133．3 Document cod e：AArticle ID：1672_5220(2013)03-0254
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4)4I ntroductionHydrostatic thrust bearings have been widely used in manyfields． The bearing catches atention due to the high loadcapacity，weal"一free between bearing surfaces．1ow friction，large fluid film stiffness and damping，reduced vibration，andgood positional accuracy．Ma et a1．studied the pressure fieldof hydrostatic thrust bearing based on computational fluiddynamics(CFD) by the software of F叫 ENT．and thepressure and temperature distribution of hybrid bearing wereobtained L ．Zhu studied pressure field in hydrostatic b~aringby finite element method． solved simple Navier—Stokesequation，and obtained the carrying capacity of oil film tochoose parameters of oi1 supplying systems． The optimaldesign of bearings was provided by these researches L ．GuoPf a1． studied oil film bearing pressure through numericalanalysis method based on flow continuity under condition oflarge whirl L ． Zheng et a1． proposed an improved finitedifference method of pressure distribution of aerostaticbearing L ．Sharma et a1．analyzed the capillary compensatedfour recesses hydrostatic journal bearing witb diferentgeometric shapes of recess L 一 ． They computed theperformance characteristies of a circular thrust pad hydrostaticbearing with circular，rectangular，and elliptical recesses bythe finite element methOd L _oJ．Osman et aL designed a testrig to study hydrostatic thrust bearing performance l川．Zhanget a1． studied the performances of heavy hydrostatic bearingsuch as load—carrying capacity and temperature field~8 l1
． Alof the above mentioned hydrostatic bearings focus on 出echaracteristies of various recess shapes such as circular an drectan gular．However。few studies have been reported aboutthe performan ce of constant flow hydrostatic thrust bearing wimmulti—pad annular recesses． In order to studv tl1e pressureperformance of constant flow hydrostatic thrust bearing havingmulti．Dad annular recesses in large—scale vertical computernumerical control (CNC) lathes， the thine—dimensionalpressure field betw een the rotary worktable and the base wascomprehensively analyzed based on the lubrication theory andC D．M eanwhile．也e impact of rotational speed of the rotaryworktable on the pressure distribution was revealed． Thereliability of a hydrostatic thrust bearing with multi—pad annularcavities can be predicted through the study.

1 Governing Equations1．1 W orking principle of hydrostatie thrustbearingTh e working principie of constant flow hydrostatic thrustbearin2 with multi Pad annular recesses is shown in Fig．1．Th elubricating oil is compulsively injected into oil cavity，andform s bearing capacity of hydrostatic bearing through throRfingaction of the gap between resistive oil edges and the rotaryworktable， then lifts bearing spindle and bears externalloads[12-13]
.

1一 Pump；2一 BaSc；3一 ROtary orktable；W- External load：．il— oil film thicknessFig．1 Working principle of constant flow hydrostatic thrust bearing1．2 Mathematical modelIn order to study the recess pressure between the rotaryworktable and the base， the fundamental equations forincompressible viscous fluids consist of mass conservationequation， momentum conservation equation， and energyconservation equation[14-15]
.

Recieyed date：2O12-08-1OFoundation items：National Natural Science Foundations of China(No．51075106，No．51oo5o63．No．50975066)：Technology Items ofHeilongjiang Provincial Educafion Department。China(No．12511087。No．12521096，No．12511086。No．12511O88。No．11551080，No.

12521119)；Projects of the Special Fund on tl1e Science and Technology Innovation People of Harbin。China(No．2012RFQXG077)；the 2012National CoHege of Innovative Pilot Project，China(No．201210214o27)+ Correspondence should be addressed to YU Xiao．dong，E-mall：hustyuxiaodong###163．comJoumal of Donghua University(Eng．Ed．)VoL 30，No．3(2013) 2551．2．1 Mass conservation equation粤+ + +O(，pw)：0， (1) df d av dz ’ 、where u，v，and w are the components of speed vector n in ，Y，and z directions；P is the density(kg／m。)；and t is the time(s).

1．2．2 M omentum conservation equationv c =一 +孥+ +鲁+ ，vc =一 + + + + '(2，+aivc =一蓑+ + +鲁 ，where Fx，Fy，and Fz are the forces on infinitesimal unit(N)；P is the pressure oil fluid infinitesimal unit(Pa)；and rn， r ，and r z arc the viscosity stresses on infinitesimal unit1．2．3 Energy conservation equation椭cpuT iv( d ) ， ㈥where Cp is the specifc heat(J／kg’K)；T is temperature(K)；k is heat transfer coeficient；and Sr is the heat sourcetem 1.

2 NumericaI Simulation2．1 M ulti-pad modelIn order to study the recess pressure，the model of the gapoi1 film between the rotary worktable and the base wasestablished．The model of the gap oil film is shown in Fig．2.

Fig．2 Model of multi—pad annular recess2．2 Grid partitionThree—dimensiona1 geometry model of the oil film isestablished by Unigraphics，and imposed into the pre—processorICEM CFD to generate grid．The tota1 number of the grid is843 438．and the quality distribution below 0．55 is 0；the gridnumber in the range of l 0．55，0．9)is 13 224，and it accountsfor the total 1．675％ ：the grid number in the range of 1 0．9，1．0]is 830 214．and it accounts for the totaI 98．325％． egrid of gap oil film is shown in Fig．3.

Fig．3 Grid ofthe gap O．1 film2．3 Boundary conditionsThe boundary conditions used for the solution of pressurefield are as follows.

(1)The pressure is 0．1 MPa on the external boundary(2)The pressure for nodes on the pocket boundary isequa1.

(3)The flow of lubricant through the hole is equal to thebearing input flow.

(4)The temperature of oil is the temperature ofsurounding atmosphere on the external boundary.

(5)The temperature of lubricant through the hole is thetemperature of the oil tank.

3 Simulation Results and DiscussionIn order to study the effect of the rotationa1 speed on theuniformity of the oi1 recess pressure field and the oi1 recesspressure．the oil recess pressure with different rotationa1 speedwas simulated．The boundary conditions are set as follows：theinlet flow capacity is 100 g／s．external pressure is 0．1 MPa，theviscosity of1ubricating oil is 0．028 8 Pa·s。andthe densityPis 900 kg／m5． The three dimensional pressure fields inworktable’s rotational speeds with 16，32，48，6 l，and 80r／min are shown in Figs．4—8．The simulation curve betweenthe rotational speed and pressure is shown in Fig．9.

172~+0135539e1005222ei 005639e{005006c+008墨 0一 ．{ (0 O25 0 075Fig．4 Pressure field in the rotational speed of】6 r／minPresure∞le{005449c+00,5190~}004。-． Io。‘0 025 0 0754：L Fig．5 Pressure field in the rotational speed of 32 r／mino__ 3；。- ． 。(?’o 025 0 O75Fig 6 Pressure field in the rotational speed of 48 r／minL黼 ㈠¨=一¨===¨== m∞鼠 瓣 黼 ==== 褂㈧ 舞“ 巴
∞ ∞ ∞ ∞ ∞ ∞ ∞ ∞ ∞ ∞ ∞D 如 Il{驰 舵 盯 鲫 ∞ ∞ 加吣 2 2 2。 ， ㈨蹴慨 雠二==二¨二二_二=粥一 一 鏊巍鼹 ㈨
256 Journal of Donghua University(Eng．Ed．)Vo1．30，No．3(2013)Pressure(Contour 1)落 ¨
78c+0053．70oe+o05i}3．322e+o5f 2．945=~0052．567e+005}j{2．I89c+o05}1．81c+05蹬 43e’o5 譬
_l-055~1005■ &774tf 1D一 ．．? ‘0 025 0．075毒 LL呻Fig．7 Pressurcfieldinthe rotational speed of64 r／rainPrcssurc(Coalour 1)■ ‘ 。

懋‘．122t·00576 005{}3．403e+005}}3．“4c+05f}2．685e 05}}2．325~~005}}I．966e+05踌 譬
I_2 c+005I 8
．88leⅧ 4[PalDl-_： I=蹦 ( )0．025 0．075Fig．8 Pressure field in the rotational speed of 80 r／min455000450000445000440000435 0004300004250004200004150004i0000405000400000◆——～ ▲—＼ ＼ ＼ ＼I l I I I16 32 48 64 80Rotational speed／(r·min一。)Fig．9 Pressures in various rotational speedThe simulation results show 也at the oil recess pressuredecreases gradually with the worktable rotational speedincreasing．Reference I l6 I studied the performance of constantflow hydrostatic thrust beating with multi—pad circular and sectorrecesses．It has also been observed that the value of pressure inthe recess and load—carying capacity for different bearingconfigurations follows the patern through comparative analysis：PannuIar>pcircuIar>psectDf，Fannular>Fcircu1ar>Fsect0rComparing with other bearings，annular recessed be aringshave the higher recess pressure and the higher load—carryingcapacity.

4 Oil Recess Pressure Experiment4．1 Experimental apparatusTh e experimental apparatus is shown in Fig．10． Th ebearing pressure is measured by twelve—YB一150B—type pressuredetectors made in Shanghai Jinzheng Instrument and MeterPlant．The designed oil film thickness of thrust bearing was0．19 mm．and the range of山c rotational speed were 0-80 r／min． Th e worktable is mounted on a vertical driving shaftsupported by angular—type ball bearing．111e outer diameter oftest bearing is 3 150 toni．and tl1e inner diameter is 2 550 mm.

Th e base has 12 annular recesses with 3 010 mm outer diameteran d 2 690 i1ii inner diameter．27 degrees angular span，an d 5mil in depth．In the center of the recess．there is a hole of 14him diameter and 200 mm depth．The low kinematic viscosity46#lubricant was used．Th e installation of 12 pressure detectorsis shown in Fig．1 1．and there is a pressure detector in eachrec ess.

Fig．10 Experimental apparatusFig．11 Installation drawing of pressure detector4．2 Experimental resultsTh e recess pressure of different rotational speed is shown inTable 1．the pressure of oil film decreases with the rotationalspeed increasing．and the recess pressure remains constant andthe pressure values of 12 oil recesses are alm ost the same underthe same rotational speed． Th e recess pressure under therotational speed 80 r／min is shown in Table 2.

Table l Oil recess pressure of diferent rotational speed已Joumal of Donghua University(Eng．Ed．)VoL 30，No．3(2013) 257Experimental and simulation results of oil recess pressureshow the simulation results agree well with the experimentaldata，an d the oil recess pressure decreases with the rotationalspeed increasing．Experimental values of the oil recess pressurewim different sensor locations are shown in Table 2．and therecess pressure of each recess is almost the same under the samerotational speed.

5 ConclusionsThe numerical simulation of the three．dimensional pressurefield of hydrostatic thrust bearing with multi—pad annular recessis achieved based on CFD and the finite volume method．Thesimulation resul~ are in accord with the experiments． Th eexperimental results show that the recess pressure decreases wi ththe rotational speed increasing．and the recess pressure of eachrecess is almost the same under the same rotational speed.

Th e results indicate that the proper selection of thegeometric shapes of the recess is essential to get an improvedperformance for a constant flow hydrostatic thrust bearing．Th ereliability of the hydrostatic thrust bearing with multi—padannular recesses can be predicted through the numericalsimulation.

Referencesl 1 I Ma T。Dai H L。Liu S R．Numerical Simulation Study on LiquidHybrid Bearing Based on FLI踟 [J]．Journal of DonghuaUniversity：Natural Science，201O，36(3)：279-282． (inChinese)I 2 I zhuXL．Simuladen ofPressureFieldinHydrostaticBearingwithFjn Element Methodl J 1．Journal of Shang ivers D厂Engineering Science，2o02，16(2)：92-95．(in Chinese)l 3 f Guo L，Li Z W 。Zhu D．0il Film Bearing Pressure NumericalAnalysis Method Based on FlOw Confinuity under Condition ofLarge I JI．Journal ofHunan University：Natural Scienee.

1998(6)：32-36．(in Chinese)I 4 I Zheng S F。Jiang S Y．Improved Finite Diference Method forPl'gsure Distribution of Aerostatic Bearing I J 1． Journal ofSoutheast University．2Oo9．25(4)：5Ol 5.

1 5 l Sharma S C，Kumar V．Jaln S C。et a1．Study of Hole．EnHybrib Joumal Bearing Sysmm Considering Combined Influenceof Thermal and Elastic Efects『J】．Tribology International。

2003。36(12)：9O3．92O.

I 6 l Sharma S C，Jain SC，BharukaDK．Influence ofRecess Shapeon the Performance of a Capillary Compensated Circular ThnlstPad Hydrostatic Bearing[J]．Tribology International，2002，35(6)：347-356.

I 7 l Osman T A。Safar Z S，Mokhtar M 0 A．Design of AnnularRecess Hydrostatic Thrust Bearing under Dynamic Loading『J].

Tribology International，l991，24(3)：137—141.

[8]Zhang Y Q，Yu x D，Yang X D，et a1．Viscosity InfluenceResearch on Load Capacity of Heavy Hydrostatic Bearing[J].

Key Engineering Materials，2010。450：63-66.

[9]Zhang Y Q，Yang x D，l_a H M，et a1．Research on In．quence ofCavity Depth on Load Capacity of Heavy Hydrostatic Bearing inVafable Viscosity Condition l J】．Advanced MateriaIs Research.

2010，129／130／131：1181．1185.

[10]Shao J P，Zhang Y Q，Li P C，et a1．Static How Simulation ofHydrostatic Bearing Elipse and Sector Curve Based on Ruent[J]．Lubrication Engineering，2oo7，32(1)：93-95． (inChinese)[11]ZhangYQ，XuxQ，YangxD，et a1．Analysis onInfluence ofo-l FiIm Tllickness on Temperature Field of Heavy HydrostaticBearing in Variable Viscosity ConditionI J I．Advanced MateHaIsResearch．2011．239／240／241／242：1418．1421.

1 l2 I Chen B X．F1uid Theory of Lubneadon and nleir AppHcafion[M]．Beijing，China：Mechanical Industry Pres，1991：13-26.

(in Chinese)[13]Pang Z c．Liquid Gas Hydrostatic Technology[M]．Harbin，China：HeilongJiang Publishing Group，l98l：26-38． (iIlChinese)l 14 l Hart Z。Wang J。Lan X P．The FLl FIuid Project SimulatesCalculating an Example and AppHes[M]．Beijing，China：Bering Institute of Technology Press，2004：56-75．(in Chinese)I 15 I Wang F J．Calculation FIow Mechanics An alyses FLUENTSoftware Principle and AppUes[M]．Beijing。China：TsinghuaUniversity Press．20o4：7．11．(in Chinese)[16]Yu x D，Meng X L，Shao J P，el a1．Comparative Study ofthePerformance on a Constant FIow An nular Hydrostatic ThrustBearing Having Multi—circular Recess and Seetor Reces l C I.

Proceedings of the 9th Intemational Conference on ElectronicMeasurement and Instruments，Beijing，China，2OO9：1oo5—1O】O.