1 Introduction. Study of the principle of measurement 2 and gauge layout position. Hiromichi Kanehara* and Kiyoshi Ohno*

Transcription

1 Special ediion paper Developmen of a Coninuous Measuring Sysem for Conac Posiion beween Wheel and Rail oward Clarificaion of Derailmen Mechanism Hiromichi Kanehara* and Kiyoshi Ohno* Safey from derailmen has been evaluaed according o he magniude of he derailmen coefficien, which does no always ensure sufficien safey evaluaion, and is no necessarily helpful in clarifying he mechanism of derailmen. To solve his problem, we have developed a sysem ha provides coninuous daa on he conac posiion beween he wheel and rail. To ensure ha oupu is delivered o a leas one bridge no maer where conac beween he wheel and rail has shifed as a resul of roaion of he wheel, wo ses of measuring bridges are provided. The oupus of boh are added afer hey have been muliplied by he weigh assigned in conformiy o he phase of he wheel roaion, whereby coninuous oupus are obained on a real-ime basis in he compuaional processing sysem ha we have developed. This sysem has allowed a conac angle and laeral angenial force o be measured. A he same ime, i provides simulaneous generaion of he laeral force value obained by correcing he influence resuling from shif of he conac posiion beween he wheel and rail in he laeral direcion. Thus, our new developmen effors have succeeded in providing he daa characerized by a greaer degree of reliabiliy han before. Keyword Wheel load, ransversal pressure, conac posiion, creep force, coninuous measuremen, car movemen 1 Inroducion Wih regard o he forces acing beween he railway wheel and rail, a coninuous measuring mehod has already been esablished for he wheel load and laeral force. The mehod is used exensively in safey evaluaion a he ime of he running es 1). In he meanime, as discussed in one of he Commenary Aricles, he laeral angenial force (laeral creep force) ha is srongly involved in derailmen can be worked ou if he wheel/rail conac posiion, wheel load, and laeral force can be measured. However, since only an inermien measuring mehod has been available so far, coninuous daa could no be obained. To solve his problem, we have developed a sysem ha permis coninuous measuremen of he wheel/rail conac posiion o clarify he relaionship beween he laeral angenial force and derailmen. Expanding he inermien 2), 3) measuring mehod for he wheel/rail conac posiion ha we developed previously, we have developed a sysem ha provides coninuous measuremens by daa processing. Sudy of he principle of measuremen 2 and gauge layou posiion Fig. 1 shows he principle of measuring he wheel/rail conac posiion. The conac posiion can be idenified by examining he disribuion of compression srain generaed by he acion poin of he wheel load along he direcion of plae hickness. To pu i more specifically, four srain gauges are aached so as o measure he compression srains across he plae hickness in he holes formed for measuremen immediaely above he load-applied porion (posiion under es) on he circumference of he wheel and on he side opposie o i, and o find ou he difference beween hem. Then a bridge configuraion is formed as shown in Fig. 2. This arrangemen allows he indicaor for he movemen of he conac posiion o be idenified afer he influence of emperaure changes in one circui has been correced. y Wheel load P z Srain P Wheel load applied on he read Wheel load applied on he neural poin Fig. 1 Principal of measuring he conac posiion Wheel load applied on he flange side 54 JR EAST Technical Review-No.2 *Safey Research Laboraory, Research and Developmen Cener of JR Eas Group

2 Special ediion paper P1 D P1 A P1D P1A P2A P1A P1 D P2 D P1D P2D P2 A P1 A Oupu Oupu ( ) Wheel load applied posiion (mm) P2 D P2 A P2D P2A Inpu Fig. 2 Conac posiion measuring bridge (inermien measuremen) This bridge oupu has dimensions of lengh by force, and is subjec o change in proporion o he magniude of he wheel load even if he conac posiion is consan. Therefore, o specify he conac posiion, i is necessary o divide he measuremen by wheel load oupu and o conver i ino he dimension of disance. Fig. 3 shows an example of he wheelse and bridge configuraion, and Fig. 4 represens an example of oupu. This bridge oupu provides wo inermien measuremens of he shif of he conac posiion wih reference o he wheel side per roaion of he wheel. Fig. 4 Conac posiion measuring bridge oupu (Resul of experimen) To ge coninuous measuremen daa using his principle of measuremen, i is necessary o provide wo or more ses of he inermien measuring bridges wih he phase shifed and o inerpolae hese oupus (i.e. find he sum by muliplying an adequae coefficien). In his case, i is essenial o arrange a srain gauge mouning posiion o ensure ha oupu is delivered o a leas one bridge no maer where conac beween he wheel and rail has shifed in he circumferenial direcion as a resul of roaion of he wheel. 7T2 8T1 8T2 8 holes 1 hole 1T2 1T1 2T1 2 holes 2T2 3T1 Mehod A Mehod B Mehod C 7 holes 7T1 6T2 6 holes 6T1 5T2 3 holes 3T2 4T1 4 holes 4T2 5 holes 5T1 Gauge symbol 1s digi : Hole posiion 2nd digi : Tread/flange side 3rd digi : Gauge number Fig. 5 Combinaion of bridge layou posiions Fig. 3 Wheelse for measuremen and gauge mouning posiion A srain gauge layou posiion adequae for coninuous measuremen of he conac posiion has been verified by conducing a saic load es, using a wheelse conaining eigh holes on each wheel used for coninuous measuremen of he wheel load and laeral force. When eigh gauge mouning posiions are arranged on he wheel on one side, here are hree possible combinaions of srain gauge layou posiions for forming one bridge, as shown in Fig. 3. Mehod A is he mehod of combining bridges for coninuous measuremen of he wheel load. I represens how o combine he bridges ha produce he sum a four posiions for he oupu proporional o he shif of he conac posiion. Mehod B refers o he mehod ha is used as an inermien JR EAST Technical Review-No.2 55

3 Special ediion paper measuring mehod. I works ou he sum of he oupus proporional o he shif of he conac posiion a wo posiions opposie o each oher. Mehod C produces he sum of he oupus proporional o he shif of he conac posiion a four posiions wih a phase difference of 9 degrees each. o he conclusion ha he configuraion of he measuring bridge according o mehod A is bes suied for coninuous measuremen of he conac posiion. Fig. 7 shows an example of bridge connecion according o his mehod. Here he wheelse for coninuous measuremen of he conac posiion is manufacured by insalling wo bridges on one wheel wih he phase shifed 9 degrees. In our experimen, one wheelse was provided wih hese hree ypes of measuremen bridges. The acion poin was shifed o 32 posiions in he circumferenial direcion and 5 posiions in he direcion of he 1T2 2T2 1F1 2F1 sleeper so ha loads were applied o he wheel. Then we examined 5T2 5F1 he relaionship beween he wheel load posiion and bridge oupu. 6T2 6F1 For each of he bridge arrangemens in hree sysems, Fig. 6 shows he relaionship beween each oupu and he posiion where wheel load was applied (in he circumferenial direcion). 6F2 5F2 6T1 5T1 Mehod A Mehod B Mehod C 2F2 1F2 2T1 1T1 Oupu /6kN Fig. 7 Example of bridge connecion for coninuous measuremen Concep of daa correcion 3 and coninuous measuremen 3.1 Correcion of es daa In addiion o he srain gauge for conac posiion measuremen, he -2 wheelse used for he field es is provided wih srain gauge bridges -4 /2 3 /2 for wheel load, laeral force and, depending on he case, laeral Loaded posiion in he circumferenial direcion angenial measuremen. These bridges are ideal if hey can produce Fig. 6 Bridge oupu in each layou mehod (Wheel load applied o he 5 mm flange from he cener posiion of he wheel read) oupus only for he force of measuremen wihou responding o oher direcions forces. However, muual inerference canno be avoided compleely, despie repeaed improvemen of he posiion In mehod A, he scope of he oupu produced for he load shif in he circumferenial direcion is wider han ha of mehod B. For he shif of he load in he sleeper direcion, here is a linear relaionship beween he bridge oupu and load applied posiion in he sleeper direcion in any posiion in he circumferenial direcion. In mehod B, he oupu level wih respec o he same load is he highes, bu he widh of oupu producion is smaller when he load has shifed in he circumferenial direcion. Thus, i has been made clear ha coninuous measuremen is possible only when more han hree bridges are used. In mehod C, he oupu level is small, and many inspecion poins are required due o variaions of four cycles per roaion of he wheel. Furher, inerpolaion is complicaed, so his mehod is no very pracical. From he resul of our experimen inroduced above, we have come and direcion of mouning he srain gauge. To solve his problem, i is necessary o check he degree of inerference and o correc he oupu as required. Table 1 shows an example where a wheelse is provided wih bridges for he measuremen of wheel load (P), laeral force (Q), longiudinal angenial force (T) and conac posiion (C) o examine he oupu when force in each direcion is applied o hem. In his case, however, he conac posiion was simulaed by applying he wheel load in he sae shifed laerally from he cener of he wheel read. Thus, dimensions are represened by (lengh) (force) in his case. Table 1 Example of he resul of inspecing he wheelse for measuremen Type of applied load Measuremen sensiiviy Wheel load 1kN 49.3 Laeral force 1kN Longiudinal angenial force 1kN Conac posiion 1kN mm JR EAST Technical Review-No.2

4 Special ediion paper-3 The resul of he es shows ha he inerference by force in oher direcions is smaller for he wheel load and longiudinal angenial force, and he gauge oupus can be used as he measuremens of he wheel load and longiudinal angenial force, wihou any modificaion. The laeral force is subjeced o a srong influence when wheel load is applied in he sae shifed laerally from he neural posiion (crosshached porion in he Table). I is necessary o use he measuremens of he wheel load and conac posiion o correc i (o eliminae he oupu componen due o eccenric wheel load). The conac posiion is subjeced o considerable influence of he laeral force in his example. This mus also be correced. The calculaion equaion for correcion is given by he numerals in Table 1 where he rue values of he wheel load, laeral force and conac posiion are assumed as P, Q and C, respecively, and he bridge oupus for measuring he laeral force and conac posiion are assumed as Qou and Cou, respecively. Q C ou ou P P Solving his for Q and C gives rue values as inermien measuremens where he muual inerference beween laeral force and conac posiion is correced. In he case of coninuous measuremen, he concep of daa correcion is he same as ha of he inermien measuremen. I should be noed, however, ha he coefficien used for correcion as shown in Table 1 is subjeced o consan change due o he phase of wheel roaion. To solve his problem, in he inspecion of he wheelse for measuremen, he load-applied posiion was moved o 32 differen posiions in he circumferenial direcion of he wheel, and each oupu was recorded. By inerpolaion of such daa, we obained 6 iems (equivalen o he resoluion of he encoder for deecion of wheel roaion phase) of inspecion daa for each roaion of he wheel. Then assuming ha phase of wheel roaion is m ( m 599), bridge sensiiviy o laeral force measuremen when laeral force is applied is QQ1 (m), he bridge sensiiviy o conac posiion pressure measuremen when laeral force is applied is QC1 (m), and he bridge sensiiviy o conac posiion measuremen when he conac posiion is shifed is CC1 (m), daa is correced according o he following equaion, where he oupus of a se of bridges for he measuremen of laeral force and conac posiion are C1ou and Q1ou, respecively, Q C and he signal of wheel roaion phase m: Q1 C1 ou ou 1 Q1 C1 CQ1(m) QQ1(m) QC1(m) CC1(m) 1 Q1 Here Q1 denoes he bridge oupu for measuring he laeral force when ransversal pressure is acually, and C1 indicaes he bridge oupu for measuring he conac posiion when he wheelse is locaed a he cener wih respec o he rack. This is no always "" due o he condiions of he equipmen used for measuremen. In acual measuremen, i is necessary o conduc a low speed raveling es and o adop he waveform, hereby deermining he zero poin of each inpu signal waveform. Solving hese equaions gives he following: For he second se of circuis, Q2 and C2 can be obained in a similar manner. Thus, we can correc he bridge oupus for he conac posiion and laeral force. 3.2 Ensuring he coninuiy of measured daa Fig. 8 shows he concep of ensuring he coninuiy of measured daa by he weighing funcion. C1 QQ1(m)*QC1(m) Q1 (Q1 Q1) *(C1 C1) ou QQ1(m)*CC1(m) CQ1(m)*QC1(m) ou CC1(m)*CQ1(m) C1 (C1 C1) *(Q1 Q1) ou QQ1(m)*CC1(m) CQ1(m)*QC1(m) ou Oupu Oupu of wo bridges wih heir phase shifed 9 degrees. Waveform by inermien signal /2 3 /2 Roaion phase Oupu CL1 by weigh 1 a a cerain roaion phase X Movemen of conac posiion Oupu Coninuous waveform /2 3 /2 Roaion phase Waveform by inermien signal /2 3 /2 Roaion phase Oupu CL2 by weigh 2 a a cerain roaion phase X Muliply boh oupus by he weighing funcion value according o phase angle, and find he sum. Fig. 8 Concep of measured daa coninuiy JR EAST Technical Review-No.2 57

5 Special ediion paper Q1, Q2, C1 and C2 obained from equaion (3) are muliplied by weigh according o he roaion angle of each wheel, as shown in equaion (4), o find he sum. Then he coninuous value for wheel roaion is obained by inerpolaion. Bridge measuremen oupu for wheel load Weighing funcion Bridge oupu for measuring laeral force (influence of he shif of conac posiion sill remains) Bridge oupu for measuring conac posiion (influence of ransversal pressure sill remains) Daa on wheel read profile C (C1 *CS1(m) C2 *CS2(m))/ P /cc Q (Q1 *QS1(m) Q2 *QS2(m))/ qq Correcion of linear simulaneous equaion wih wo unknowns Q : True laeral force (coninuous value) C : True conac posiion (coninuous value) P : True wheel load (coninuous value) Q1, Q2 : Laeral force bridge oupu afer correcion C1, C2 : Conac posiion bridge oupu afer correcion Qs1(m), Qs2(m) : Weighing funcion for laeral force Cs1(m), Cs2(m) : Weighing funcion for conac posiion qq : Laeral force bridge sensiiviy cc : Conac posiion bridge sensiiviy (Exising coninuous measuring sysem for wheel load and laeral force) Coninuous measuremen of wheel load (rue value) Bridge oupu for measuring laeral force (rue value) Weighing funcion Coninuously measured value for laeral force (rue value) Laeral angenial force Bridge oupu for measuring conac posiion (rue value) Divided by wheel load Movemen of conac posiion Weighing funcion Coninuously measured value for conac posiion movemen (rue value) Geomeric conversion Conac angle (Newly developed measuring sysem) Laeral force and conac posiion weighing funcions can be creaed from he daa a he ime of inspecion, by using he weighing funcion creaing rouine of he coninuous measuring sysem for wheel load and laeral force. We used he wheel load P loaded from he exising coninuous measuring sysem for wheel load and laeral force. 3.3 Processing of laeral angenial force If he conac angle beween he wheel load and laeral force is known in addiion o he wheel load and laeral force, he componen (laeral angenial force) in he direcion of conac surface can be idenified by geomeric compuaion. This is very helpful. Thus, he relaionship beween he conac poin posiion on when wheel and conac angle was incorporaed ino he compuaional processing sysem in he form of a able, hereby calculaing he laeral angenial force Fy from equaion (5) and oupuing he resul. Fy Q *cos P * sin where denoes a conac angle corresponding o he conac poin on he wheel. Furher, Q/P, i.e. derailmen coefficien is also produced. Fig. 9 is a flow char represening he daa processing flow: Fig. 9 Daa processing flow 4 Configuraion of daa processor We have developed a sysem ha execues daa processing discussed in Chaper 3 on a real-ime basis o produce coninuous oupus. Fig. 1 shows he configuraion of his sysem. The bridge oupu for each of he righ and lef wheels and roaion phase signal obained by dividing he porion on he wheel ino 6 equal pars are loaded ino he sysem a every sampling ime of.5 or 1 ms hrough an inpu filer (variable in he range from 2 Hz o 1 khz). Afer analogo-digial conversion using 12 bis, compuaion according o equaions (3) o (5) is performed by he DSP (Digial Signal Processor). The resul of compuaion is subjeced o digial-o-analog conversion and is oupu as analog signals for each se of he righ and lef wheels hrough an oupu filer (variable wihin he range from 2 Hz o 1 khz). A he same ime, i is recorded in a buil-in hard disk drive as a digial signal in a log file.daa on correcion coefficiens, weighing funcions, wheel read profile daa required for compuaion is colleced in an inspecion of he wheelse for measuremen conduced in advance, and is sored as a parameer file on he hard disk drive of he processor so ha he daa can be referred o whenever required in compuaion. Fig. 11 shows he exernal view of he measuring sysem. 58 JR EAST Technical Review-No.2

6 Special ediion paper-3 laeral force and derailmen coefficien, he influence due o he L1 L2 q L1 q L2 Inpu filer A/D converer L1 : Lef: Conac posiion oupu 1 L2 : Lef: Conac posiion oupu 2 Q : Lef: laeral force oupu 1 L1 : Lef: laeral force oupu 2 L2 DSP operaion par DSP : TMS32 C671 Conroller CPU : Celeron 5Mhz Monior movemen of conac posiion is correced. Therefore, hese oupus are generally greaer on he inner rack side han he oupus by he exising coninuous measuring sysem for wheel load and laeral force, and are smaller on he ouer rack side, as verified in our ess. L : Lef: wheel load RAM : 128MB When compared wih he resul of simulaion, he oupus of he righ P/Q coninuous measuring sysem CLK : Clock R : Righ: wheel load HDD : 9GB FDD : 3.5inch CDROM : 32 Nework : Eherne : WindowsNT Keyboard Mouse and lef angenial forces seem generally appropriae. In a final operaion verificaion es, his sysem was mouned on he es rain on he Kawagoe line in he running es having sared in February 22, and measuremen was carried ou in he running es R1 R2 q R1 q R2 Inpu filer R1 : Righ: Conac posiion oupu 1 R2 : Righ: Conac posiion oupu 2 Q : Righ: laeral force oupu 1 R1 : Righ: laeral force oupu 2 R2 of acual cars. Fig. 12 shows an example of he measured waveforms. This example shows he resul of running in a sraigh line, a curve and a sraigh line, in ha order. Immediaely before he curve, he L R Encoder Lef encoder signal Righ encoder signal conac posiion exhibis a big movemen of he righ and lef wheels in a direcion opposie o each oher on a periodic basis, wihou L R Oupu filer D/A converer much laeral force. This suggess ha he wheelse made a sligh zigzag movemen. Upon enering he curve, he wheelse is moved o he ouer rack Fig. 1 Configuraion of a prooype measuring sysem due o he difference in wheel diameers. So he conac posiion on Fig. 11 Exernal view of a coninuous measuring sysem for wheel/rail conac posiion 5 Bench es and enaive use in a field es Using a prooype coninuous measuring sysem, we conduced a funcion es using simulaed signals o verify he weighing funcion and various ypes of compuaional processing, and o improve he conrol program. Afer ha, a bench es was conduced using he inpu signal daa for his sysem colleced in he previous acual running ess. In hese ess, we made comparison wih he resul of simulaion and he VTR showing he saus of wheel read conac a he ime of running es. I has been confirmed ha he values for he oupu of he conac posiion are generally appropriae. For he oupus of he Fig. 12 Example of waveform measured in he acual running es JR EAST Technical Review-No.2 59

7 Special ediion paper he ouer rack side(lef side) moves o he flange and ha on he inner(righ) goes o he read side. There is almos no change during he ravel on he curve. (Laeral force also exhibis ransiion of an almos consan magniude). I can be seen ha zigzag movemen occurs when he rain has enered he sraigh line afer running hrough he curve. As described above, i has been verified ha a predeermined measuremen can be performed, wihou any paricular problem in he real-ime measuremen in he field es, similarly o he case of he bench es. 6 Conclusion The conac posiion beween he wheel and rail could no be measured in he field es even hough i consiues an imporan facor of rain moion. To solve his problem, we have developed a compuaional processing sysem, where wo measuremen bridges are mouned on he wheel wih a phase difference of 9 degrees, and he oupus of boh are added afer hey have been muliplied by he weigh assigned in conformiy o he phase of he wheel roaion. Thus, coninuous oupus are obained on a real-ime basis. This sysem provides simulaneous generaion of he laeral force value obained by correcing he influence resuling from shif of he conac posiion beween he wheel and rail, and also produces he laeral angenial force. Thus, his sysem has succeeded in providing daa characerized by much higher accuracy han ha of he convenional processor. before can be provided by a combined use of he coninuous measuring sysem for wheel load and laeral force. (3) Alhough he relaionship wih derailmen has been poined ou so far, acual measuremen has no been possible while a rain was raveling, so he laeral creep force has no been used for evaluaion of safey from derailmen. We can now use his laeral creep force as an evaluaion indicaor. I has become clear ha raveling safey canno be deermined only by a linear form or running condiions, as in he case of low-speed raveling a he oule of a sharp curve. We have paid paricular aenion o iem (3), and are making effors for collecion of he measured daa in a running es wihin he railroad compound. In he fuure, hrough concurren use of a compuer simulaion, we are aiming a furher clarificaion of he relaionship beween force acing beween wheel and rail in various direcions and behavior of he wheelse. This is expeced o make a conribuion when we propose effecive measures for prevening climbing derailmen accidens. In he meanime, he sysem iself sill has a problem; namely, he porion equivalen o user inerface has no ye sufficien developed. I is no a sysem ha can be used by everybody a presen. While verifying he usefulness of his sysem, we will make furher effors o improve he sysem, and prepare and improve he operaion manuals and relaed documens. 7 Subsequen commimen The developmen of his sysem has led o he furher clarificaion of he behavior of he wheelse while raveling han he previous level. I is expeced o make a conribuion o evaluaion of raveling safey and clarificaion of he derailmen mechanism. Specific mehods of applicaion can be enumeraed as follows: (1) Since i is possible o specify he conac posiion wih he rail assuming he wheel side as a reference, he new sysem idenifies how far he wheel has climbed he rail, hereby direcly conribuing o evaluaion of raveling safey. (2) For laeral force measuremen, if he conac posiion is known, i is possible o correc he error caused by he influence of is movemen. Therefore, measuremens of higher accuracy han References: 1) ISHIDA, MATSUO, TEZUKA and UEKI: Collecive Research Paper Read a he Japan Sociey Of Mechanical Engineers (Version C), No ) KANEHARA and FUJIOKA: Railway Car Rail - Field Tes of Conac Posiion beween Wheels, Collecive Research Paper Read a he Eighh Meeing of he Traffic and Physical Disribuion Session, The Japan Sociey Of Mechanical Engineers (1999), pp ) KANEHARA and FUJIOKA: Collecive Research Paper of The Japan Sociey Of Mechanical Engineers (Version C), No JR EAST Technical Review-No.2