METHOD AND DEVICE FOR DETERMINING THE LONGITUDINAL FORCES IN TRACK RAILS

Abstract

A method for determining the longitudinal forces in track rails includes shifting a rail section of at least one of the track rails from an initial arrangement into a test arrangement by providing a test force, recording at least one force measurement value correlating with the test force in the test arrangement, and determining the longitudinal forces in the at least one track rail on the basis of the at least one force measurement value. At least one sleeper is attached to the rail section when the at least one force measurement value is recorded. A device for carrying out the method is also provided.

Claims

1-15. (canceled)

16. A method for determining longitudinal forces in track rails, the method comprising: shifting a rail section of at least one of the track rails from an initial arrangement into a test arrangement by providing a test force; recording at least one force measurement value correlating with the test force in the test arrangement, with at least one sleeper being attached to the rail section when recording the at least one force measurement value; and determining the longitudinal forces in the at least one track rail by using the at least one force measurement value.

17. The method according to claim 16, which further comprises keeping the rail section in a negotiable assembly state when the at least one force measurement value is recorded.

18. The method according to claim 16, which further comprises determining a neutral temperature of the at least one track rail based on the longitudinal forces.

19. The method according to claim 16, which further comprises recording at least one distance measurement value correlating with a deflection of the at least one track rail between the initial arrangement and the test arrangement.

20. The method according to claim 16, which further comprises using a lifting and lining unit of a track construction and maintenance machine to carry out the shifting.

21. The method according to claim 16, which further comprises compacting a track bed on which the rail section is based.

22. The method according to claim 16, which further comprises determining the longitudinal forces by taking into account a bedding stiffness of a track bed on which the rail section is based.

23. The method according to claim 22, which further comprises determining the bedding stiffness at least one of based on at least one compaction measurement value recorded during compaction of the track bed or based on the at least one force measurement value correlating with the test force.

24. The method according to claim 16, which further comprises determining the longitudinal forces by analytical methods.

25. The method according to claim 16, which further comprises determining the longitudinal forces by the finite element method.

26. The method according to claim 16, which further comprises determining the longitudinal forces based on at least two of the force measurement values, correlating with test forces in respectively different test arrangements.

27. A device for determining longitudinal forces in track rails, the device comprising: a test device for shifting the rail section and for recording the at least one force measurement value to carry out the method according to claim 16.

28. The device according to claim 27, which further comprises a running trailer for travelling on a track, the test device being attached to the running trailer.

29. The device according to claim 28, wherein the test device is configured to shift the rail section of the track rail carrying the running trailer.

30. The device according to claim 27, which further comprises a tamping unit for compacting a track bed on which the rail section is based.

Description

[0033] Further features, details, and advantages of the invention result from the following description of an embodiment based on the figures. The following figures show:

[0034] FIG. 1 a side view of a device, in particular a track construction and maintenance machine, for determining the longitudinal forces in rails, having a test device for shifting a rail section, with the rail section being arranged in an initial arrangement,

[0035] FIG. 2 a side view of the device in FIG. 1, with a test force being exerted on the rail section by means of the test device and with the rail section being arranged in a test arrangement,

[0036] FIG. 3 a structural model of the rail section in FIG. 2 for determining the longitudinal forces using the at least one force measurement value, and

[0037] FIG. 4 a free body diagram of a section of the structural model in FIG. 3 with the cutting forces acting at the cut boundaries.

[0038] With reference to FIGS. 1 to 4, an embodiment of a device 1 for determining the longitudinal forces in track rails 2 is described. The device 1 has a running trailer 3 for travelling on a track 4 and a test device 5 for shifting a rail section 6 of the at least one track rail 2 and for recording at least one force measurement value.

[0039] The track 4 is arranged on a track bed 7, in particular a ballast bed. Two track rails 2 that are arranged parallel and spaced apart from each other are attached to sleepers 8. The sleepers 8 rest on the track bed 7. The track 4 is in a negotiable assembly state.

[0040] The running trailer 3 is arranged on the track rails 2 for travelling on the track 4. The running trailer 3 comprises two bogies 9 and a support frame 10 attached to it. The bogies 9 have rail-guidable wheels 11. At least one traction motor 12 of the running trailer 3 provides the drive power required to shift it along the track 4.

[0041] The test device 5 comprises a lifting and lining unit 13. The lifting and lining unit 13 has a grapple 14 for reversible gripping the track rail 2. One lifting actuator 15 per track rail 2 is provided for shifting the rail section 6 along a vertical direction z. A lining actuator, not shown, is designed to shift the at least one track rail 2 in a horizontal direction y orientated perpendicular to a longitudinal direction x of the track 4. The respective lifting actuator 15 and the respective lining actuator are designed as fluidic, in particular hydraulic, actuators. The lifting actuator 15 and/or the lining actuator are preferably designed to effect a test force F.sub.P, in particular via the grapple 14, on the respective track rail 2.

[0042] The lifting and lining unit 13 has a force measuring means 16 which is designed to record a force measurement value which correlates with the test force F.sub.P for shifting the at least one rail section 6 between an initial arrangement and a test arrangement. The force measuring means 16 is preferably designed as a load cell. The lifting and lining unit 13 also has a distance measuring means for each lifting actuator 15 and each lining actuator for recording a distance measurement value w, which correlates with a vertical and/or horizontal deflection of the at least one track rail 2, in particular the rail section 6, in particular in the area of the grapple 14, between the initial arrangement and the test arrangement. The respective distance measuring means 17 preferably has at least one regulating distance sensor, in particular a potentiometer, for detecting a regulating distance of the respective lifting actuator 15 and/or the respective lining actuator.

[0043] The lifting and lining unit 13 is attached to the support frame 10. A supply device 18 of the device 1 provides the electrical and fluidic power required to operate the device 1, in particular the hydraulic power required to operate the respective lifting actuator 15 and the lining actuator.

[0044] The device 1 has a tamping unit 19 for compacting the track bed 7 on which the track 4 is based. The tamping unit 19 is attached to a tamping segment frame 21 via a vertically orientated linear bearing 20. The tamping segment frame 21 is attached to the support frame 10. A vertical drive 22 is designed to shift the tamping unit 19 along the linear bearing 20.

[0045] The tamping unit 19 comprises two tamping tines 23 and a tamping drive 24. The tamping drive 24 is designed to swivel the tamping tines 23 around horizontal tamping tine axes 25. A combined swivelling and vibrational movement around the respective tamping tine axis 25 is transmitted to the tamping tines 23 by means of the tamping drive 24.

[0046] The tamping drive 24 comprises electrical and/or fluidic, in particular hydraulic actuators. The tamping drive 24 is connected to the supply device 18 in a power-transmitting manner. The tamping unit 19 is supplied with the required electrical and/or fluidic power by means of the supply device 18.

[0047] The device 1 has a control device 26. The control device 26 is in signalling connection with the lifting and lining unit 13 and the tamping unit 19, in particular also with the running trailer 3 and the supply device 18. The control device 26 is designed to control the arrangement of the track 4, in particular the at least one track rail 2, by means of the lifting and lining unit 13. Furthermore, the control device 26 is designed to control the compaction of the track bed 7 by means of the tamping unit 19. In particular, the control device 26 is designed to control the supply device 18 and/or the travelling movement of the running trailer 3 along the track 4.

[0048] The tamping unit 19 has a reaction force measuring means, not shown, for recording a reaction force measurement value which correlates with a ballast force acting between the track bed 7 and the tamping tines 23. The reaction force measuring means can, for example, be designed as a pressure sensor for recording the hydraulic pressure in a hydraulic actuator of the tamping drive 24. Preferably, the reaction force measuring means is designed to record a reaction force measurement value which acts between the at least one tamping tine 23 and the track bed 7 when the at least one tamping tine 23 penetrates the track bed 7, in particular in the vertical direction, and/or during a cyclic movement, in particular a vibrational movement, of the at least one tamping tine 23. The reaction force measurement value can correlate accordingly with the penetration force acting on the at least one tamping tine 23 and/or a vibration force acting on the at least one tamping tine 23 during compaction.

[0049] Furthermore, the device 1 comprises a temperature measuring means 27 for determining the temperature of the at least one track rail 2. The temperature measuring means 27 is designed as a pyrometer. It is in signalling connection with the control device 26.

[0050] An evaluation device 28 of the device 1 is designed to determine the longitudinal forces in the at least one track rail 2 on the basis of a signal from the force measuring means 16, in particular also on the basis of signals from the respective distance measuring means 17, the reaction force measuring means, and/or the temperature measuring means 27.

[0051] The mode of operation of the device 1 for determining the longitudinal forces in track rails 2 is as follows:

[0052] FIG. 1 shows the device 1, in a first working position. In the first working position, the device 1 is positioned on the track 4. The tamping tines 23 of the tamping unit 19 are not engaged with the track bed 7. The two rail sections 6, arranged in pairs, overlap the lifting and lining unit 13, the two grapples 14, and the tamping unit 19 along the longitudinal direction x. The lifting and lining unit 13 is positively connected to the rail sections 6 via the two grapples 14. In the first working position, the lifting and lining unit 13 does not exert any force on the track 4, in particular the rail sections 6 of the track rails 2. The two track rails 2, in particular the rail sections 6, are located in the initial arrangement.

[0053] To determine the longitudinal forces in the two track rails 2, the control device 26 provides a signal to activate the two lifting actuators 15 on the supply device 18. The lifting actuators 15 provide the test force F.sub.P and move the two grapples 14 with the rail sections 6 upwards in the vertical direction z. The device 1 is in the second working position shown in FIG. 2. The two track rails 2, in particular the rail sections 6, are located in the test arrangement.

[0054] The vertical deflection w is determined by the distance of the respective rail section 6 between the initial arrangement and the test arrangement at the point where the test force F.sub.P is applied, i.e. at the respective grapple 14. The respective distance measuring means 17 of the lifting and lining unit 13 records the distance measurement value correlating with the regulating distance of the associated lifting actuator 15 and correspondingly with the vertical deflection w. The force measuring means 16 is used to record a force measurement value that correlates with the test force F.sub.P acting on the respective track rail 2 via the respective grapple 14.

[0055] The track rails 2 are attached to the sleepers 8 in the test arrangement, in particular when recording the at least one force measurement value. In the test arrangement, the track 4, in particular in the area of the at least one rail section 6, is in a negotiable assembly state.

[0056] The temperature measuring means 27 records, in particular without contact, a temperature measurement value that correlates with the temperature of the respective track rail 2.

[0057] The control device 26 provides a signal to start compacting the track bed 7. The tamping unit 19 is lowered by means of the vertical drive 22. The tamping tines 23 penetrate the track bed 7. The tamping tines 23 are swivelled around the respective tamping tine axis 25 and subjected to a vibrational movement. The ballast of the track bed 7 is compacted in the area below the tamping unit 19. A reaction force measurement value is recorded during compaction of the track bed 7 using the reaction force measuring means. The compaction process is ended and the tamping unit 19 is shifted back into the first working position.

[0058] The longitudinal forces, in particular a normal force N, in the track rails 2 are determined using the recorded force measurement values, distance measurement values, temperature measurement values, and reaction force measurement values. Information regarding the weight-based line load based on the linear weight q.sub.g of the track rails 2 is stored in the evaluation device 28. Furthermore, the evaluation device 28 comprises information about the resulting linear weight q.sub.s of the sleepers 8 along the longitudinal direction x. This linear weight q.sub.s of the sleepers 8 corresponds to the quotient of the average weight of the individual sleeper 8, in particular within the rail section 6, and the average distance l.sub.s between the central longitudinal axes of two adjacent sleepers 8. Also stored in the evaluation device 28 is information relating to the modulus of elasticity E, the cross-sectional area A and the coefficient of thermal expansion .sub.T of the track rails 2 and the surface moment of inertia I of the track rails 2 about the horizontal transverse axis y and/or about the vertical axis z. The longitudinal forces in the at least one track rail 2 are preferably determined on the basis of the surface moment of inertia I of the track rail 2 about the horizontal transverse axis y when the rail section 6 is shifted in the vertical direction z and/or on the basis of the surface moment of inertia I of the track rail 2 about the vertical axis z when the rail section 6 is shifted in the horizontal direction y.

[0059] A bedding modulus k of the track bed 7 is stored in the evaluation device 28. The bedding modulus k corresponds to the stiffness of the track bed 7 in the vertical direction z. The bedding modulus k is determined, in particular adjusted, using the reaction force measurement value.

[0060] The longitudinal forces, in particular the normal forces N, the normal stress ON and/or the longitudinal strain EN, in the track rails 2 are calculated using the information described above. According to a first embodiment, the calculation is performed exclusively on the basis of an FEM model stored in the evaluation device 28.

[0061] Furthermore, a neutral temperature T.sub.N of the respective track rail 2 is determined. The neutral temperature T.sub.N is the temperature at which the longitudinal forces, in particular normal forces N, in the track rails 2 become zero. For this purpose, the test temperature T.sub.P of the track rails 2 is determined using the temperature measurement value that is present when the at least one force measurement value is recorded. The neutral temperature T.sub.N of the respective rail section 6 is determined from this as follows:

[00001]$T_N=T_P+\frac{N}{\mathrm{EA}{}_T}$

[0062] To determine the test temperature T.sub.P, the temperature measurement value is preferably recorded multiple times during the passage over the respective rail section 6 by means of the temperature measuring means 27. An average value can be determined from the multiple measurement values, which enables particularly precise determination of the test temperature T.sub.P. Local temperature fluctuations and measurement deviations can be compensated for by averaging.

[0063] According to an alternative embodiment, the longitudinal forces, in particular the normal force N, the normal stress ON and the longitudinal strain EN, in the respective track rail 2 can be determined using analytical methods. The respective track rail 2 is modelled as an elastically embedded beam on the basis of Bernoulli's linear beam theory. The track bed 7 is modelled based on the previously known Winkler bedding modulus method. The boundary value problem for the vertical deflection w along the longitudinal direction x can be described as follows:

[00002]${\mathrm{EIw}}^{}\left(x\right)+k\left(w\left(x\right)\right)w\left(x\right)=q_g+q_s.$

[0064] The support points of the wheels 11 closest to the lifting and lining unit 13 are assumed to be locating bearings with respect to the longitudinal direction x, from which follows

[00003]$\begin{array}{c}{w}^{}\left(x=0\right)=w^{}\left(x=l\right)=0,\\ -{\mathrm{EIw}}^{}\left(x=0\right)=F_{R1},\mathrm{and}\\ -{\mathrm{EIw}}^{}\left(x=l\right)=F_{R2}.\end{array}$

[0065] F.sub.R1 and F.sub.R2 are the vertical transverse forces acting on the wheels 11 on the track rails 2. is an indicator function for the loss of bedding due to the test force F.sub.P, which is determined according to

[00004]$\left(w\left(x\right)\right)=\frac{1}{2}\left[\tan h\left(w\left(x\right)\right)+1\right].$

[0066] The ballast parameter describes the transition between the area of the rail section 6 resting on the track bed 7 and the area of the rail section 6 that is out of contact with the track bed 7. Preferably, the bedding parameter is assumed to be significantly greater than the maximum value of the vertical deflection w. To determine the vertical deflection w(x), the above differential equation can be solved numerically. Based on this, the positions x.sub.A and x.sub.B are determined in which the transverse forces Q.sub.A=Q (x=x.sub.A), Q.sub.B=Q (x=x.sub.B) are equal to zero. In these positions, the track rail angles , corresponding to the gradient of the track rails 2 are determined as follows:

[00005]$\begin{array}{c}\tan =w^{}\left(x_A\right),\mathrm{and}\\ \tan =w^{}\left(x_B\right).\end{array}$

[0067] The equilibrium of forces in the vertical direction provides the normal force N to be determined according to

[00006]$N=\frac{F_P-\left(x_B-x_A\right)*\left(q_s+q_g\right)}{\sin +\sin }.$

[0068] Alternatively, the track rail angles , can be determined approximately as the quotient of the vertical deflection w and an empirically determined length value, which correlates with the distance between the positions x.sub.A, x.sub.B. Using the normal force N, the normal stress .sub.N can be determined as follows:

[00007]${}_N=\frac{N}{A}.$

[0069] The longitudinal strain EN can be calculated as follows according to

[00008]${}_N=\frac{N}{\mathrm{EA}}.$

[0070] Preferably, the at least one force measurement value correlating with the test force F.sub.P is recorded at at least two different vertical deflections w. In particular, a progression of the at least one force measurement value over the vertical deflection w can be determined. This allows the longitudinal forces in the respective track rail 2 to be determined multiple times, in particular during the shifting of the rail section 6 between the initial arrangement and the test arrangement. By averaging these multiple longitudinal forces, an increase in accuracy can be achieved. Furthermore, the weight of the respective track rail 2 and/or the sleepers 8 can be deduced from this. The longitudinal forces in the track rails 2 can therefore be determined particularly reliably and precisely.

[0071] Preferably, a computer program product is provided for carrying out the method described above. The computer program product can be stored on a memory unit, in particular the evaluation device 28.

[0072] The fact that the method can be carried out while the track 4 is in a negotiable assembly state means that the longitudinal forces in track rails 2 can be determined in a particularly time-efficient and economical manner. The at least one sleeper 8 attached to the rail section 6 is included in the determination of the longitudinal forces, as described above, in particular by taking into account its weight and the track bed 7 acting on it. Removing the connection between the track rails 2 and the sleepers 8 to determine the longitudinal forces can be avoided. Non-destructive testing of track 4 is possible. In particular, the method can be carried out independently of the difference between the neutral temperature T.sub.N and the test temperature T.sub.P. In particular, the test temperature T.sub.P for carrying out the method can be greater than the neutral temperature T.sub.N because there is no risk of shifting the track rails 2 relative to the sleepers 8.

[0073] The fact that the method is carried out by means of the device 1, in particular by means of a track construction and maintenance machine, means that the longitudinal forces can be determined in a particularly economical manner. A corresponding device 1 has a particularly wide range of applications. The compaction of the track bed 7 and the determination of the longitudinal forces can be carried out at least partially in parallel by means of the device 1 and thus be particularly time-efficient.