Method of operating a tamping unit of a track maintenance machine, and a tamping device for ballast bed consolidation, and a track maintenance machine

Abstract

In a method of operating a tamping unit of a track maintenance machine, the track maintenance machine having the tamping unit is first provided on a track bed. The tamping unit is displaced relative to the track bed. A driving force, acting on the tamping unit and required for the displacement, and acceleration acting on the tamping unit are determined. A ballast force acting between the tamping unit and the track bed is determined by way of the driving force and the acceleration, and is evaluated.

Claims

1. A method of operating a tamping unit of a track maintenance machine, which comprises the steps of: providing on a track bed the track maintenance machine having a tamping unit; displacing the tamping unit relative to the track bed; determining a driving force acting on the tamping unit and required for a displacement; determining an acceleration acting on the tamping unit; determining a ballast force, acting between the tamping unit and the track bed, by way of the driving force and the acceleration; evaluating the ballast force, wherein the evaluating takes place in such a way that a strain acting on the tamping unit is determined by way of the ballast force; and determining a wear condition of the tamping unit based on the strain.

2. The method according to claim 1, which further comprises determining the acceleration by measuring a temporal change of a position of the tamping unit.

3. The method according to claim 1, wherein for determining the ballast force, an inertial force acting on the tamping unit is determined by means of the acceleration.

4. The method according to claim 1, wherein the displacement of the tamping unit occurs by means of a fluidically operated drive device, wherein at least one fluid pressure acting on the fluidically operated drive device is measured for determining the driving force.

5. The method according to claim 1, which further comprises determining the strain by way of a temporal progression of the ballast force.

6. The method according to claim 1, which further comprises determining the strain by means of ballast force amplitudes of the ballast force.

7. The method according to claim 6, wherein for determining the strain, a load spectrum is determined by way of a cumulative frequency of the ballast force amplitudes.

8. The method according to claim 1, wherein for determining the strain, a ballast work is determined from the ballast force and a change of a position of the tamping unit.

9. The method according to claim 1, which further comprises setting at least one process parameter for controlling the tamping unit in dependence on the strain.

10. A method of operating a tamping unit of a track maintenance machine, which comprises the steps of: providing on a track bed the track maintenance machine having a tamping unit; displacing the tamping unit relative to the track bed; determining a driving force acting on the tamping unit and required for a displacement; determining an acceleration acting on the tamping unit; determining a ballast force, acting between the tamping unit and the track bed, by way of the driving force and the acceleration; evaluating the ballast force, wherein the evaluating takes place in such a way that a strain acting on the tamping unit is determined by way of the ballast force; setting at least one process parameter for controlling the tamping unit in dependence on the strain; and changing the at least one process parameter when a threshold value of the strain is exceeded or fallen below.

11. A method of operating a tamping unit of a track maintenance machine, which comprises the steps of: providing on a track bed the track maintenance machine having a tamping unit; displacing the tamping unit relative to the track bed; determining a driving force acting on the tamping unit and required for a displacement; determining an acceleration acting on the tamping unit; determining a ballast force, acting between the tamping unit and the track bed, by way of the driving force and the acceleration; evaluating the ballast force, wherein the evaluating takes place in such a way that a strain acting on the tamping unit is determined by way of the ballast force; setting at least one process parameter for controlling the tamping unit in dependence on the strain; and setting the at least one process parameter such that the strain does not exceed a strain limit value.

12. A tamping device for track bed consolidation, the tamping device comprising: a unit carrier; a tamping machine supported on said unit carrier; a driver for providing a driving force and for displacing said tamping machine relative to said unit carrier; a driving force sensor system for detecting a first measuring value corresponding to the driving force; an acceleration sensor system for detecting a second measuring value corresponding to an acceleration of said tamping machine; and an evaluation unit for determining a ballast force, acting on said tamping machine by means of the first measuring value and the second measuring value, wherein said evaluation unit is configured to determine a strain acting on said tamping unit based on the ballast force, said evaluation unit further configured to determine a wear condition of said tamping unit based on the strain.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) Additional features, advantages and details of the invention become apparent from the following description of an example of embodiment. There is shown in:

(2) FIG. 1 a schematic representation of a rail-guided track maintenance machine having a tamping device for track bed consolidation,

(3) FIG. 2 a schematic front view of the tamping device in FIG. 1, wherein the tamping device comprises a tamping unit having four tamping tines and wherein the tamping tines are in engagement with a track bed,

(4) FIG. 3 a schematic side view of the tamping device in FIG. 1, wherein a driving force, an inertial force and a ballast force act on the tamping unit,

(5) FIG. 4 progressions of the driving force, the inertial force and the ballast force over time and for an individual tamping cycle,

(6) FIG. 5 progression of the ballast force over time for six tamping cycles,

(7) FIG. 6 progression of measured load amplitudes of the ballast force over a number of stress cycles, and

(8) FIG. 7 progressions of a position of the tamping unit, the ballast force and a ballast work over time.

DETAILED DESCRIPTION OF THE INVENTION

(9) A track maintenance machine 1 comprises a machine frame 2, at least two axles 3 supported on the machine frame 2, a machine drive 4, and a tamping device 5 for track bed consolidation. The axles 3 are arranged on the track maintenance machine 1 at a distance from one another along a horizontal x-direction. The x-direction, together with a vertical z-direction and a horizontal y-direction, forms a machine-fixed coordinate system. Rail-guidable wheels 6 are rotatably mounted on the axles 3. The machine drive 2 is designed for rotary actuation of the wheels 6 of at least one of the axles 3.

(10) The tamping device 5 has a unit carrier 7 and a tamping unit 8 mounted relative to the same in the z-direction. The tamping unit 8 comprises four tamping tines 8a and a consolidation drive 8b. The tamping tines 8a are installed in each case on a tamping tine carrier 8c and mounted via the latter for rotation about a carrier axis 8d. By means of the consolidation drive 8b, the tamping tine carriers 8c can be rotatably driven about the respective carrier axis 8d.

(11) The tamping device 5 is mounted on the machine frame 2 by way of the unit carrier 7. The tamping unit 8 is displaceable relative to the unit carrier 7. To that end, a linear bearing 10 is formed between the unit carrier 7 and the tamping unit 8. The linear bearing 10 has bearing rails 11 mounted on the unit carrier 7 and bearing sleeves 12 connected to the tamping unit 8.

(12) The tamping device further has a drive device 9. The drive device 9 includes a hydraulic cylinder 13. The hydraulic cylinder 13 acts between the unit carrier 7 and the tamping unit 8. A hydraulic piston 14 with a piston rod 15 attached thereto is mounted for linear displacement in the hydraulic cylinder 13. The hydraulic piston 14 has a piston ring surface A.sub.KR facing towards the piston rod 15, and a piston surface A.sub.K facing away from the piston rod 15. In this, a piston pressure p.sub.K of a hydraulic fluid located in the hydraulic cylinder 13 acts on the piston surface A.sub.K. A piston ring pressure p.sub.KR of the hydraulic fluid acts on the piston ring surface A.sub.KR. From the piston pressure p.sub.K acting on the piston surface A.sub.K and the piston ring pressure p.sub.KR acting on the piston ring surface A.sub.KR, a driving force F.sub.A results which is transmitted as a whole via the piston rod 15 to the tamping unit 8.

(13) The tamping device 1 includes a driving force sensor system for recording a first measuring value P.sub.K, p.sub.KR, F.sub.A corresponding to the driving force F.sub.A. The driving force sensor system has a piston pressure sensor 16 for recording the piston pressure p.sub.K and a piston ring pressure sensor 17 for recording the piston ring pressure p.sub.KR. From the piston pressure p.sub.K acting on the piston surface A.sub.K and from the piston ring pressure p.sub.KR acting on the piston ring surface A.sub.KR, it is possible to draw a conclusion as to the driving force F.sub.A acting overall via the piston rod 15 on the tamping unit 8. The driving force F.sub.A is computed as follows:
F.sub.A=p.sub.KR.Math.A.sub.KR−p.sub.K.Math.A.sub.K  (1)

(14) The tamping device 1 has an acceleration sensor system for recording a second measuring value corresponding to an acceleration a, of the tamping unit 8, the position z and/or the speed v.sub.z. The acceleration sensor system is designed as a path transducer 18. The path transducer 18 is mounted on the unit carrier 7 and on the tamping unit 8. The path transducer 18 is designed for recording the position z and the speed v.sub.z of the tamping unit 8 relative to the unit carrier 7 in the z-direction.

(15) For determining the ballast force F.sub.S acting on the tamping unit 8, the tamping device 5 includes an evaluation unit 19. The evaluation unit 19 is in signal contact with the piston pressure sensor 16, the piston ring pressure sensor 17 and the path transducer 18. Additionally, the evaluation unit 19 is in signal contact with a pressure regulator 20. The pressure regulator 20 is designed for regulating the piston pressure p.sub.K and the piston ring pressure p.sub.KR to a respective target value. The respective target value for the piston pressure P.sub.K and the piston ring pressure p.sub.KR can be prescribed by the evaluation unit 19.

(16) The operation of the track maintenance machine 1 and the operation of the tamping unit 8 are described below:

(17) For creating and/or maintaining a track bed 21, the track maintenance machine 1 is moved by means of the machine drive 4 in the x-direction along a track 22. During this, a center axis 23 of the tamping device 5 is positioned centrally over a railroad sleeper 24 arranged on the track bed 21 and supporting the rails 22.

(18) At the start of the process of track bed consolidation, the tamping unit 8 is situated in a reset position 25. The bearing sleeve 12 is situated at an upper end of the linear bearing 10, and the piston rod 15 plunges to a large extent into the hydraulic piston 14. The tamping tines 8a mounted on the tamping unit 8 are not in engagement with the track bed 21. The piston surface A.sub.K is pressurized with the piston pressure P.sub.K, and the piston ring surface A.sub.KR is pressurized with the piston ring pressure p.sub.KR. By means of the evaluation unit 19, the driving force F.sub.A acting by the hydraulic piston 14 on the tamping unit 8 is determined. To that end, the piston pressure p.sub.K is multiplied with the piston surface A.sub.K, and the piston ring pressure p.sub.KR is multiplied with the piston ring surface A.sub.KR. Thus, the following applies for the driving force F.sub.A:
F.sub.A=p.sub.KR.Math.A.sub.KR−p.sub.K.Math.A.sub.K  (2)

(19) In the reset position 25, the tamping unit 8 rests relative to the unit carrier 7, and only the gravitational acceleration g acts on the tamping unit 8. For the acceleration a.sub.z of the tamping unit 8 relative to the unit carrier 7, a.sub.z=0 applies, and F.sub.S=0 applies for the ballast force F.sub.S. For the equilibrium of forces on the tamping unit 8 along the z-direction, the following applies:
ΣF.sub.z=F.sub.A+F.sub.T+F.sub.S=F.sub.A−m*(a.sub.z+g)+F.sub.S=0  (3)

(20) Prior to the start of operation of the tamping device 5, the mass m of the tamping unit is determined in the reset position 25 by means of the evaluation unit 19. Taking into account the limiting conditions prevailing in the reset position 25, the following applies for the mass m:
m=F.sub.A/g  (4)

(21) The mass m of the tamping unit 8 is stored in a memory element of the evaluation unit 19.

(22) The consolidation of the track bed 21 is subdivided into individual tamping cycles. During the tamping cycle, the tamping unit 8 is shifted along the z-direction from the reset position 25 into a squeezing position 26 and an engagement position 27. In the squeezing position 26, the tamping tines 8a touch the track bed 21, but do not penetrate the same. In the engagement position 27, the tamping tines 8a penetrate into the track bed 21. The tamping cycle is finished when the tamping unit 8 is shifted from the engagement position 27 via the squeezing position 26 back again into the reset position 25. The ballast force F.sub.S is determined by means of the evaluation unit 19 from the inertial force F.sub.T and the driving force F.sub.A. For determining the inertial force F.sub.T, first the speed v.sub.z of the tamping unit 8 relative to the unit carrier 7 in the z-direction is determined as change of the position over the time t. The acceleration a.sub.z, in turn, is determined as change of the speed v.sub.z over the time t. The acceleration a.sub.z is thus determined as follows:

(23) $\begin{array}{cc}{a}_z\left(t\right)=\frac{d{v}_z\left(t\right)}{dt}=\frac{d^{2}z\left(t\right)}{d{t}^2}& \left(5\right)\end{array}$

(24) With the start of the tamping cycle starts the evaluation of the ballast force F.sub.S(t) dependent on the time t. By way of the driving force F.sub.A(t) and the acceleration a.sub.z(t) as well as with the knowledge of the mass m and the gravitational acceleration g, the ballast force F.sub.S(t) is determined as follows:
F.sub.S(t)=−F.sub.T(t)−F.sub.A(t)=m[a.sub.z(t)+g]−F.sub.A(t)  (6)

(25) In order to shift the tamping unit 8 from the reset position 25 against the z-direction into the squeezing position 26, first the drive device 9 is activated. During this, the piston pressure p.sub.K is increased and the piston ring pressure p.sub.KR is lowered. The driving force F.sub.A acting via the piston rod 15 on the tamping unit 8 is increased counter to the z-direction. From the driving force F.sub.A, the acceleration a.sub.z acting on the tamping unit 8 results, which is oriented against the z-direction and leads to an increase of the speed v.sub.z of the tamping unit 8 in the direction of the track bed 21. The tamping unit 8 is displaced against the z-direction. The inertial force F.sub.T of equal magnitude acts counter to the driving force F.sub.A. Prior to contact of the tamping tines 8a with the track bed 21, the ballast force F.sub.S equals zero.

(26) In the squeezing position 26, the tamping tines 8a get to engage the track bed 21. Between the squeezing position 26 and the engagement position 27, the partial ballast forces F.sub.S1, F.sub.S2, F.sub.S3 and F.sub.S4 additionally act on the tamping unit 8 in the z-direction via the four tamping tines 8a. the partial ballast forces F.sub.S1, F.sub.S2, F.sub.S3 and F.sub.S4 add up to the ballast force F.sub.S. Throughout the displacement between the squeezing position and the engagement position 27, the ballast force F.sub.S is not equal to zero.

(27) The progressions of the driving force F.sub.A, the inertial force F.sub.T and the ballast force F.sub.S over the time t for the duration of a tamping cycle are shown in detail in FIG. 4. The displacement of the tamping unit 8 between the reset position 25 and the engagement position 27 takes place in the squeezing phase 28. The return phase 29 follows the squeezing phase 28 with a time delay.

(28) In the return phase 29, the tamping unit 8 is shifted back from the engagement position 27 via the squeezing position 26 into the reset position 25. To that end, the drive device 9 is operated in such a manner that the piston pressure p.sub.K is reduced and the piston ring pressure p.sub.KR is increased. The hydraulic cylinder 13 thus produces the driving force F.sub.A which is now oriented in the z-direction. The tamping unit 8 is accelerated in the z-direction because of the driving force F.sub.A. The acceleration a.sub.z is oriented in the z-direction and results in a speed v.sub.z, which increases in the z-direction, and the displacement of the tamping unit 8 in the z-direction. Between the engagement position 27 and the squeezing position 26, the ballast force F.sub.S acts on the tamping unit 8. Between the squeezing position 26 and the reset position 25, only the drive force F.sub.A and the inertial force F.sub.T, which is of equal magnitude and oriented oppositely, act on the tamping unit 8, wherein the ballast force F.sub.S equals zero.

(29) During the tamping cycle, the tamping tines 8a are set in vibration by activation of the consolidation drive 8b. To that end, the consolidation drive 8b drives the tamping tine carrier 8c essentially in horizontal direction, as a result of which the tamping tine carrier 8c and the tamping tines 8a mounted thereon rotate about the respective carrier axis 8d. The motion of the tamping tines 8a about the respective carrier axis 8d includes essentially two motion components. A vibration component causes a merely small rotation amplitude of the tamping tines 8a about the respective carrier axis 8d, wherein a vibration frequency f.sub.S is between 35 Hz and 45 Hz. The vibration frequency acts on the tamping tines 8a during the entire tamping cycle. In addition to the vibration component, the tamping tines 8a are actuated with a displacement component. The displacement component has a greater rotation amplitude than the vibration component and a displacement frequency of about 0.5 Hz. In the engagement position 27, the tamping tines 8a are rotated about the respective carrier axis 8d in such a way that the tamping tines 8a—spaced from one another in the x-direction—move towards one another. In the reset position 25, the displacement component is oriented such that the tamping tines 8a move apart from one another again. The actuation of the tamping tines 8a with the displacement component follows in the displacement phase 30. As a result of the superimposed actuation of the tamping tines 8a with the vibration component and the displacement component, the track bed 21 is consolidated.

(30) The tamping cycle is finished as soon as the tamping unit 8 is in the reset position 25 again. For further consolidation of the track bed 21, the track maintenance machine 1 is displaced in the x-direction until the center axis 23 is arranged centrally above the railway sleeper 24 following next in the x-direction. Here the tamping cycle is repeated. The progression of the ballast force F.sub.S over the time t is shown for six successive tamping cycles in FIG. 5.

(31) By means of the evaluation unit 19, the strain on the tamping udv 5 is determined by way of the temporal progression of the ballast force F.sub.S. The strain is determined on the basis of ballast force amplitudes S.sub.F.sub.S of the ballast force F.sub.S. The ballast force F.sub.S is an oscillating load varying over time. The ballast force amplitude S.sub.F.sub.S is determined as the difference of a maximal ballast force F.sub.S and a minimal ballast force F.sub.S within an oscillation. In addition to the ballast force amplitudes S.sub.F.sub.S, the cumulative frequency N.sub.F.sub.S of the respective ballast force amplitude S.sub.F.sub.S is determined. For establishing the strain, a load spectrum is determined on the basis of the cumulative frequency N.sub.F.sub.S.

(32) Shown in FIG. 6 is a progression of the ballast force amplitude S.sub.F.sub.S over the cumulative frequency N.sub.F.sub.S. By comparison of the progression of the ballast force amplitude S.sub.F.sub.S over the cumulative frequency N.sub.F.sub.S to a maximally allowable cumulative frequency N.sub.F.sub.S of ballast force amplitude S.sub.F.sub.S, a wear condition of the tamping unit 8 is established. The wear condition is established for individual parts of the tamping unit 8, such as the tamping tines 8a, the drive device 9 and the linear bearings 10, as well as for the tamping unit 8 in its entirety.

(33) In dependence upon the strain, at least one process parameter p.sub.K, p.sub.KR, f.sub.S for operation of the tamping unit 8 is set by means of the evaluation unit 19. To that end, the evaluation unit 19 is in signal connection with the consolidation drive 8b for controlling the vibration frequency frames, and with the pressure regulator 20 for controlling the piston pressure p.sub.K and the piston ring pressure p.sub.KR. Upon transgression of a threshold value SW of the strain, the at least one process parameter p.sub.K, p.sub.KR, f.sub.S is changed. To that end, the ballast force F.sub.S is compared to the threshold value SW by means of the evaluation unit 19, wherein—upon transgression of an upper threshold value SW.sub.1—the at least one process parameter p.sub.K, p.sub.KR, f.sub.S is changed in such a way that the ballast force F.sub.S is reduced, wherein—in the case of falling below a lower threshold value SW.sub.2—the at least one process parameter p.sub.K, p.sub.KR, f.sub.S is changed in such a way that the ballast force F.sub.S is increased. The ballast force F.sub.S is reduced by increasing the vibration frequency f.sub.S and by reducing the pressure difference between the piston pressure p.sub.K and the piston ring pressure p.sub.KR, and is increased in the opposite manner. The process parameters p.sub.K, p.sub.KR, f.sub.S are changed by means of the evaluation unit 19 to the extent that there is an optimum between a low strain on the tamping device 5 and a high speed of treatment of the track bed 21.

(34) As an alternative to determining the load spectrum for establishing the strain, it is also possible to determine a ballast work W.sub.S by means of the evaluation unit 19. The ballast work W.sub.S is determined from the ballast force F.sub.S and a change of the position z of the tamping unit 8. The ballast work W.sub.S corresponds to the work introduced into the track bed 21 via the tamping tines 8a. In this, the change of the position z is recorded via a discrete duration. This change of the position z is then multiplied by the ballast force F.sub.S. The ballast work W.sub.S is determined as the sum of the products of the ballast force F.sub.S and the changes of the positions z.

(35) In FIG. 7, the progressions of the position z, the ballast force F.sub.S and the ballast work W.sub.S are indicated for a tamping cycle over the time t. The ballast work W.sub.S can also be understood as the area under the progression of the ballast force F.sub.S over the position z.

(36) As a result of determining, by means of the evaluation unit 19, the ballast force F.sub.S acting on the tamping unit 8, it is possible to draw conclusions regarding the strain of the tamping unit 8. The determination of the ballast force F.sub.S while taking into account the driving force F.sub.A and additionally the acceleration a.sub.z is significantly more precise as compared to looking exclusively at the driving force F.sub.A for determining the ballast force F.sub.S. The strain of the tamping unit 8 can thus be determined reliably, and a wear condition of the tamping unit 8 can be positively detected. The adjustment of the at least one process parameter p.sub.K, p.sub.KR, f.sub.S in dependence on the strain enables the efficient and economic operation of the track maintenance machine. In this, particularly by means of optimizing, a high speed of treatment, a low energy consumption and a reduced strain on the tamping unit 8 are achieved.