EP3631087B1 - Method and device for compressing a track ballast bed - Google Patents

Description

Field of technology

The invention relates to a method for compacting a track ballast bed by means of a tamping unit, which comprises two opposite tamping tools, which are subjected to vibrations during a tamping process and are lowered into the track ballast bed and moved towards one another with a set-up movement. The invention also relates to a device for carrying out the method.

State of the art

Railway lines with ballasted superstructures require regular correction of the track position, with track tamping machines or switch tamping machines or universal tamping machines being used as a rule. Such machines, which can be moved cyclically or continuously on the track, usually comprise a measuring system, a lifting / straightening unit and a tamping unit. The track is raised to a predetermined position by means of the lifting / straightening unit. To fix this new position, tamping tools located on the tamping unit are used to tamp track ballast from both sides under a respective sleeper of the track and compact it.

Depending on the condition of the track ballast (new position, beginning of service life, end of service life) or depending on the rate of deterioration, a corresponding overcorrection of the track position is appropriate so that the track takes the desired final position through subsequent settlement. Settlement takes place, if necessary, through stabilization by means of a dynamic track stabilizer and in any case through the subsequent regular load on the train traffic.

Various designs are known for tamping units for tamping under sleepers of a track. For example disclosed AT 350 097 B a tamping unit in which hydraulic auxiliary drives are linked to a rotating eccentric shaft for the transmission of vibrations. Out AT 339 358 B we know a tamping unit with hydraulic drives that serve in a combined function as auxiliary drives and as vibration generators.

AT 515 801 A4 describes a method for compacting a track ballast bed by means of a tamping unit, whereby a quality number for a ballast bed hardness is to be shown. For this purpose, a support force of a support cylinder is recorded as a function of a support path and a code number is defined using an energy consumption derived therefrom. However, this figure has little informative value because a not negligible amount of energy that is lost in the system is not taken into account. In addition, the total energy actually introduced into the ballast during a tamping process would not allow a reliable assessment of the condition of the ballast bed. Summary of the invention

The invention is based on the object of specifying an improvement over the prior art for a method and a device of the type mentioned at the beginning.

According to the invention, this object is achieved by a method according to claim 1 and a device according to claim 14. Dependent claims specify advantageous embodiments of the invention.

The method is characterized in that, by means of sensors arranged on the tamping unit, at least for one tamping tool, a curve of a force acting on the tamping tool over a path covered by the tamping tool is recorded during a vibration cycle and that at least one parameter is derived from this, by means of which an evaluation of the Tamping process and / or a condition of the track ballast bed takes place. In this way, the tamping unit is used as a measuring device during an operational use in order to record a force-displacement curve (working diagram) of the tamping tool and to derive a meaningful parameter from it.

Specifically, the compacting process serves as a measuring procedure to determine the load-deformation behavior of the track ballast and its changes Place to be determined. By analyzing the measured variables in real time and generating at least one parameter, the track ballast quality and compaction can already be assessed online during the compaction process. As a result, process parameters of compaction and the corrected track position can be continuously adjusted. For example, a default value for overcorrection of the track position can be derived from the evaluation of the ballast bed quality.

In addition, it is advantageous if the parameter is specified as a parameter for controlling the tamping unit. The automated adjustment of the tamping process achieved in this way allows a quick reaction to a changing condition of the ballast bed. For example, several provision processes can be carried out automatically until a specified degree of ballast compaction is achieved.

An advantageous embodiment of the invention provides that a maximum force acting on the tamping tool during the oscillation cycle is derived as a first parameter in order to evaluate a ballast condition or a compression condition of the ballast bed. This first parameter takes into account that the track ballast can only oppose the tamping tool with a limited force (reaction force). The maximum force depends on the one hand on the phase of the tamping process in which the examined oscillation cycle is and on the other hand on the condition of the ballast. Thus, the first parameter is a meaningful indicator both for the ballast condition (new ballast offers higher resistance) and for the compaction condition (increase in the course of compaction).

In a meaningful development, an oscillation amplitude occurring during the oscillation cycle is derived from the recorded force-displacement curve as a second parameter in order to evaluate a compression state of the ballast bed. To determine the amplitude, reversal points of the dynamic tamping tool movement can be determined in absolute coordinates and / or relative coordinates (dynamic oscillation path). It is taken into account that both the The provision movement and the dynamic tamping tool movement are not exclusively path-controlled due to the design.

In addition, it is advantageous if, in order to evaluate a ballast condition of the ballast bed for the oscillation cycle, an occurrence of contact between the tamping tool and ballast and a loss of contact between the tamping tool and ballast are determined and a third parameter is derived from this. In a provision phase, there is a pronounced asymmetrical load on the tamping tool, the processing direction of the ballast in the direction of the sleeper to be tamped being given by the provision movement. The position of a contact entry point and the position of a contact loss point depend on the state of the ballast. In the force-displacement curve, a section with contact and a section without contact therefore provide good indicators for the quality of the track ballast.

Another advantageous evaluation of the force-displacement curve provides that, as a fourth parameter, an inclination of the curve during a loading phase of the tamping tool is derived. This inclination of the working line in the load branch of the working diagram provides information about the load-bearing capacity of the track ballast as load rigidity. It increases in the course of the compaction of the ballast and is used as proof of compaction.

In order to evaluate the ballast condition, an inclination of the course during a relief phase of the tamping tool is advantageously derived as a fifth parameter. This inclination of the working line in the relief branch of the working diagram is to be regarded as relief stiffness. New ballast shows some elastic behavior when the load is removed and springs back with the tamping tool when it moves backwards until it loses contact. Old gravel, on the other hand, hardly reacts elastically. Therefore the unloading stiffness is a good indicator of the condition of the ballast.

To determine a degree of utilization, it is advantageous if a deformation work performed by means of the tamping tool is derived from the recorded profile as a sixth parameter. These The work of deformation corresponds to the area enclosed by the working line. It is that part of the work of the drive of the tamping unit that is transferred to the track ballast in order to cause compaction, displacement, flow of the ballast, etc. With this sixth parameter, the efficiency of the track plug can be optimized in a simple manner.

Another improvement provides that a total inclination of the course is derived as a seventh parameter in order to determine an overall stiffness of the ballast bed. In a phase of penetration into the track ballast, the tamping tool works in both directions, as the lack of a provision movement means that it also introduces dynamic forces into the ground on its rear side. Due to the bilateral mode of action, the physical sense of loading and unloading stiffness becomes obsolete and the overall stiffness is represented by the inclination of the working line.

It is advantageous here if the overall inclination is determined by linear regression of the recorded profile, for example using the least square error method.

In a further development of the method according to the invention, the course of the force acting on the tamping tool over the path covered by the tamping tool is recorded for several oscillation cycles of a tamping process, a value being determined for each of these oscillation cycles for each parameter and using a course of these determined parameters or by means of several characteristic value curves an evaluation process takes place. Depending on the parameter used, conclusions about the gravel condition and / or the compaction condition can be easily drawn from the characteristic value curve.

In addition, it is advantageous if several provision processes are carried out at a track location, whereby for each provision process a value for one oscillation cycle or a characteristic value curve for several oscillation cycles is determined for each parameter for evaluating a compaction state of the ballast bed, and if a specified compaction state is not achieved further provision process is carried out. The characteristic values or characteristic value curves show clear differences between the successive provision processes.

An additional development of the method provides that a characteristic value for one oscillation cycle or a characteristic value curve for several oscillation cycles is determined for several tamping processes at different points along a track and that an evaluation of a spatial development of a compaction success and / or the nature of the ballast bed is made from this . This superordinate course of the parameters over several tamping processes provides information about the homogeneity of the track, the condition of the ballast and the success of compaction.

The device according to the invention for carrying out one of the aforementioned methods comprises a tamping unit with two opposite tamping tools, each of which is coupled via a swivel arm with an auxiliary drive and a vibration drive, with sensors on at least one swivel arm and / or the assigned tamping tool for detecting the course of the the force acting on the stuffing tool are arranged over the path covered by the stuffing tool, measurement signals from the sensors being fed to an evaluation device, and the evaluation device being set up to determine a parameter derived from the course.

It is advantageous if at least one force measuring sensor is arranged in a tamping tool holder. The force measuring sensor is thus protected from disruptive influences and measures the forces acting on the tamping tool with high accuracy. A bend in the tamping tool is easily compensated for. In addition, acceleration sensors or displacement sensors are arranged to detect the tamping tool path.

Brief description of the drawings

Fig. 1

Stopfaggregat

Fig. 2

Stopfwerkzeug und Schwenkarm mit Sensoren

Fig. 3

Kraft-Weg-Verlauf (Arbeitsdiagramm) bei neuem Schotter

Fig. 4

Kraft-Weg-Verlauf bei altem Schotter

Fig. 5

Kraft-Weg-Verlauf beim Eindringen in den Schotter

Fig. 6

3D-Diagramm der Kraft-Weg-Verläufe für mehrere Schwingungszyklen bei neuem Schotter

Fig. 7

3D-Diagramm der Kraft-Weg-Verläufe für mehrere Schwingungszyklen bei altem Schotter

Fig. 8

Schnittflächen durch das 3D-Diagramm gemäß Fig. 6

Fig. 9

Schnittflächen durch das 3D-Diagramm gemäß Fig. 7

Fig. 10

Verläufe der Maximalkraft bei zwei Beistellvorgängen

Fig. 11

Verläufe der Belastungssteifigkeit bei zwei Beistellvorgängen

Fig. 12

Verläufe der Entlastungssteifigkeit bei zwei Beistellvorgängen

Fig. 13

Verläufe der Lagen des Kontakteintrittspunktes bei zwei Beistellvorgängen

Fig. 14

Verläufe der Lagen des Kontaktverlustpunktes bei zwei Beistellvorgängen

Fig. 15

Verlauf der Maximalkraft bei neuem Schotter

Fig. 16

Verlauf der Belastungssteifigkeit bei neuem Schotter

Fig. 17

Verlauf der Entlastungssteifigkeit bei neuem Schotter

Fig. 18

Verlauf der Maximal kraft bei altem Schotter

Fig. 19

Verlauf der Belastungssteifigkeit bei altem Schotter

Fig. 20

Verlauf der Entlastungssteifigkeit bei altem Schotter

The invention is explained below by way of example with reference to the accompanying figures. It shows in a schematic representation:

Fig. 1

Tamping unit

Fig. 2

Tamping tool and swivel arm with sensors

Fig. 3

Force-displacement curve (work diagram) for new ballast

Fig. 4

Force-displacement curve for old gravel

Fig. 5

Force-displacement curve when penetrating the gravel

Fig. 6

3D diagram of the force-displacement curves for several oscillation cycles with new ballast

Fig. 7

3D diagram of the force-displacement curves for several oscillation cycles with old gravel

Fig. 8

Cut surfaces through the 3D diagram according to Fig. 6

Fig. 9

Cut surfaces through the 3D diagram according to Fig. 7

Fig. 10

Course of the maximum force with two provision processes

Fig. 11

Load stiffness curves for two provision processes

Fig. 12

Gradients of the unloading stiffness with two provision processes

Fig. 13

Course of the positions of the contact entry point for two provision processes

Fig. 14

Course of the positions of the contact loss point in two provision processes

Fig. 15

Course of the maximum force with new gravel

Fig. 16

Course of the load stiffness with new ballast

Fig. 17

Course of the relief stiffness with new ballast

Fig. 18

Course of the maximum force with old gravel

Fig. 19

Course of the load stiffness with old gravel

Fig. 20

Course of the unloading stiffness in old gravel

Description of the embodiments

Fig. 1 shows a track 1 with a track grid consisting of sleepers 2, rails 3 and fastening means 4, which is mounted on a ballast bed 5. A tamping unit 7 is positioned at a point 6 on the track 1 to be machined. This comprises two opposing tamping tools 8 (tamping tines) which enclose the sleeper 2 to be tamped during a tamping process 9. In this case, four pairs of swivel arms, each with two pairs of tamping tools, are usually arranged along a sleeper 2.

Each tamping tool is coupled to an auxiliary drive 11 and a vibration drive 12 via a swivel arm 10. Vibrations 13 are generated, for example, by means of a rotating eccentric shaft. An eccentric shaft housing together with a rotary drive is attached to a lowerable tool carrier 14 on which the two pivot arms 10 are also articulated. As an alternative to this, a vibration drive 12 can also be arranged on the respective articulation. In such an arrangement - not shown - the tamping tools 8 move along elliptical paths.

Each swivel arm 10 acts as a two-armed lever, the associated tamping tool 8 being fastened in a tamping tool holder 15 on a lower lever arm. An upper lever arm is coupled to the vibration drive 12 via the auxiliary drive 11, which is designed as a hydraulic cylinder.

When the track 1 is tamped, the track grid 4 is first raised, as a result of which cavities 16 are formed under the sleepers 2. The tamping unit 7 is positioned at the point 6 to be processed above a threshold 2 and the tamping tools 8 are subjected to the vibrations 13 by means of the vibration drive 12. Specifically, the generated vibrations 13 cause rapid opening and closing of the tong-shaped movable tamping tools 8 with a small amplitude (vibration). There is still no contact with ballast 17.

The actual stuffing process 9 is divided into several phases. In a first phase, the tool carrier 14 with the tamping tools 8 is lowered into the sleeper compartments located next to the sleeper 2. The respective tamping tool 8 penetrates vertically into the ballast bed 5, the vibrations 13 or dynamic movements making it easier to displace the ballast 17.

While the lowering is still in progress, in a second phase a setting movement 18 begins and the respective tamping tool 8 moves towards the sleeper 2. The lowering ends at a defined penetration depth and the setting movement 18 is continued. During the provision movement 18, ballast 17 is tamped under the sleeper 2 by means of the tamping tools 8, compressed and, if necessary, displaced laterally. Included The vibrations 13 are still superimposed on the provision movement 18, which is mainly used for transporting gravel (vibration at approx. 35 Hz). With this dynamic compaction of the ballast 17, so-called ballast flow can also be caused.

Before the respective tamping tool 8 touches the threshold 2, a movement reversal begins in a third phase. The tool carrier 14 together with the tamping tools 8 is moved upwards and a return movement 19 (counter-rotating positioning movement) causes the tipping tools 8, which are opposite in the form of pliers, to open.

A force measuring sensor 20 is arranged in the stuffing tool holder 15. Alternatively, sensors (strain gauges) can also be arranged on a shaft of a tamping tool 2 provided for the measurements. A horizontal contact force 21 with the ballast 17 ( Fig. 2 ). In addition, the swivel arms 10 are equipped with acceleration sensors 22 (depending on the machine type, one or two acceleration sensors 22 are used per swivel arm 10). An absolute set travel 23 is measured by means of a travel measuring sensor 24 (for example a laser sensor). Track tamping machines often have several tamping units 7. Each of these units 7 is then conveniently equipped with sensors 20, 22, 24.

Measurement signals 25 detected by means of sensors 20, 22, 24 are fed to an evaluation device 26. This evaluation device 26 is set up to process the measurement signals 25 in order to detect a force acting on the tamping tool 2 under consideration over a path covered by the tamping tool. Specifically, the horizontal contact force 21 is determined over an oscillation path 27 as a force-path curve 28 (working diagram).

In order to determine the dynamic oscillation path 27, the oscillation paths of the acceleration sensors 22 are first determined by double integration of the acceleration signals. The oscillation path 27 at the free end of the tamping tool (pick plate) is determined via the known geometric relationships.

Cutting forces (moments, normal force, transverse force) are determined on the basis of the force measurement on the shank of the stuffing tool 2. From this, the evaluation device 26 calculates the horizontal contact force 21. This contact force 21 corresponds to the reaction force of the ballast 17 on the displacement impressed on it. A bending of the tamping tool 2 can be compensated in a simple manner with the measured force. The determined tamping tool movements are also used to compensate for the inertia of the tamping tool 2.

The result of these sensor signal evaluations is the force-displacement curve 28 for the individual oscillation cycles 29 of a provision process. This relationship between the tamping tool movement and the contact force 21 is subsequently used to evaluate the compaction process and the condition of the ballast 17 or the ballast bed 5.

Exemplary force-displacement curves 28 for an oscillation cycle 29 are shown in FIG Figures 3-5 shown. The oscillation path 27 is indicated on an abscissa and the contact force 21 is indicated on an ordinate. The force-displacement curve 28 itself is shown in the form of a working line 30. These working diagrams have distinguishing features that allow a clear conclusion to be drawn about the conditions prevailing during the measurement. In particular, conclusions can be drawn about the respective work phase (lowering, setting aside or setting aside), the state of compaction and the state of the ballast (new, freshly broken ballast or old, dirty, rounded ballast). Fig. 3 shows a working diagram for new ballast, which shows sharp edges and a high degree of toothing. Fig. 4 shows a working diagram for old ballast with rounded edges, little toothing, high compaction and a high proportion of fine particles. The distinguishing features (parameters) of the work diagrams allow an automated division into condition categories such as new ballast, ballast with a short useful life and ballast with an advanced or ending useful life.

The distinguishing features that can be used as parameters are a maximum force 31, an oscillation amplitude 32, a front reversal point 33, a rear reversal point 34, a contact entry point 35, a Contact loss point 36, an incline 37 of the working line 30 during a loading phase (loading rigidity), an inclination 38 of the working line 30 during a relieving phase (unloading rigidity), a total inclination 39 of the working line and a deformation work performed 40 as an area enclosed by the working line 30. To determine these parameters 31-40, the absolute additional paths 23 can also be used instead of the relative oscillation paths 27.

The work-integrated measurement and determination of parameters and the evaluation of the ballast condition based on this allow ongoing quality control and the optimization of the process parameters of the tamping process 9. The condition of the track ballast 17 can be evaluated using the two extremes, the new ballast from a quarry and the old ballast at the end of it technical lifespan. Depending on the ballast quality, pollution, environmental influences and subsoil conditions, the ballast condition goes through all intermediate stages, whereby ballast processing or mixing of ballast can also take place during maintenance measures. Specifically, it can be determined that new ballast 17 is clean, has sharp edges and has a defined grain size distribution. Old ballast 17, on the other hand, is dirty, has rounded edges and has a different grain size distribution due to dirt, abrasion, grain fragmentation and fine particles from the subsoil.

In addition, the work-integrated determination of the ballast stiffness and the evaluation of the compaction condition based thereon allow ongoing quality control and the optimization of the process parameters of the tamping process 9. The compaction condition of the track ballast 17 can be assessed on the basis of specific ballast properties. Loosely poured ballast is loosely stored and has a large pore volume and low load-bearing capacity. Relatively large deformations occur under loads, which are mostly irreversible. The rigidity of such uncompacted ballast is low. Compressed gravel, on the other hand, is densely packed and has a low pore volume. Due to the compression, deformations are largely anticipated, which is why only under load more minor deformations occur. These are predominantly elastic, i.e. reversible. Compacted gravel has great rigidity.

The defined parameters 31-40 of an oscillation cycle 29 characterize the tamping process 9 in such a way that statements can be made in a simple manner about the condition of the track ballast and the compression process. For this purpose, either the parameters 31-40 or working diagrams are displayed in an output device or compared with a predefined evaluation scheme. Individual parameters 31-40 can be specified as parameters for controlling the tamping unit 7. For this purpose, data are transferred from the evaluation device 26 to a machine control 41.

In the following exemplary description of the relationships, the force-displacement curves 28 are interpreted in a simplified manner. For the sake of clarity, existing cross-references are not discussed. Rather, links between parameters 31-40 and assessable mechanisms with the most obvious correlations are emphasized.

The maximum force 31 is a good indicator for both the ballast condition and the compaction condition. The oscillation amplitude 32 is determined by the reversal points 33, 34 of the dynamic tamping tool movement. As the resistance of the ballast 17 increases, there is a slight reduction in the oscillation amplitude 32, which is why this second parameter is a good indicator of the state of compaction.

The contact entry point 35 and the contact loss point 36 separate in the force-displacement curve 28 a section with non-positive contact between the tamping tool 8 and ballast 17 from a section without contact. In the working diagram it can be seen that the tamping tool 8 hits the ballast 17 in a forward movement, the contact force 21 rises to the maximum 31 and then falls again because the tamping tool 8 has reached the front reversal point 33 and begins to move backwards again. In this backward movement it loses contact with the ballast 17 pressed in the working direction and carries out the rest of the backward movement with negligible force. Only after The change in direction at the rear reversal point 34 moves the tamping tool 8 again in the working direction in order to come into contact with the track ballast again. In the Figures 3 and 4 it is clear that the position of the contact points 35, 36 depend on the state of the gravel. The position of the line of contact and the line of loss of contact can therefore be used as indicators for the ballast quality.

The load stiffness of the track ballast 17 is the relationship between the force and the associated deformation. In the force-displacement curve 28, it is represented as the inclination of the working line 30 in a load branch. The load stiffness is an essential parameter for assessing the load-bearing capacity of the track ballast. It increases in the course of the compaction of the ballast and is used as proof of compaction.

The relief stiffness is represented as the incline of the working line 30 in a relief phase. In Fig. 4 the contact force 21 already decreases before the reversal point 34 due to the reduction in the deformation speed, although the deformation is still increasing. Because of this inelastic behavior, old track ballast 17 has a low, often even negative, relief stiffness. This makes the relief stiffness suitable as an indicator of the condition of the ballast.

Die Effizienz des Gleisstopfens ist mit dieser Kenngröße optimierbar, indem das Stopfaggregat 7 in der Weise betrieben wird, dass sich für die Verformungsarbeit 40 ein Maximum ergibt.The area enclosed by the working line 30 corresponds to the deformation work 40 performed. With the relative oscillation path x _rel , the contact force F and an oscillation cycle duration T, the deformation work W is calculated according to the following formula: $$\mathrm{W.}={\displaystyle \underset{\mathrm{T}}{\oint }\mathrm{F.}\cdot {\mathrm{dx}}_{\mathrm{rel}}}$$

The efficiency of the track tamping can be optimized with this parameter in that the tamping unit 7 is operated in such a way that the deformation work 40 results in a maximum.

Fig. 5 shows a working diagram in the phase of penetration, in which the stuffing tool 8 acts approximately symmetrically in both directions. The working line 30 resembles an oval. The resistance of the ballast 17 can be described by the rigidity, which is represented as the inclination of this oval. Specifically, the total inclination 39 is the inclination of a line 42 which is determined by linear regression using the least squares method.

In an advantageous embodiment of the invention, all parameters 31-40 are calculated for each oscillation cycle 29 and the course is evaluated over the entire provision process. In the Figures 6 and 7 such courses are shown in a spatial diagram. An x-axis and a y-axis correspond to the abscissa and the ordinate in FIGS Figures 3-5 . A release time 43 (sequence of oscillation cycles 29) is indicated on the third axis. In Fig. 6 it can be clearly seen, for example, that with new ballast 17 the maximum force 31 increases significantly with increasing provision time 43.

Fig. 8 shows the same measurement results as FIGS. 6 and 9 shows the same measurement results as Fig. 7 . However, the force curve is shown here as isolines 45 (isarithms) of equal force 21. The distance between these lines shows the inclination 37, 38 in the working diagram (eg load stiffness). Course and size characterize the compaction process in new gravel 17 ( Fig. 8 ) and old gravel 17 ( Fig. 9 ). A line of the layers 46 of the contact entry points 35 and a line of the layers 47 of the contact loss points 36 are also drawn in here. For the respectively constant contact force 21, a different hatching is shown as the value increases. A corresponding legend is Fig. 8 attached.

the Figures 10-14 show characteristic value curves for a sequence of several oscillation cycles 29 with two provision processes at a point 6 on track 1. These are discrete curves of those characteristic values (values of the respective parameter 31-40) that are recorded in the respective oscillation cycle 29. The characteristic value curves for a first provision process 48 and a second provision process 49 are shown together in the respective diagram and each begin with the first oscillation cycle 29 of the respective provision process 48, 49 Decision criterion how many tamping processes 9 are required per track position 6. The difference between the first and the second provision process 48, 49 is clearly recognizable and thus justifies the second process 49.

In the Figures 15-20 characteristic value curves for a sequence of several tamping processes 9 or threshold positions at successive points 6 along the track 1 are shown (spatial development). The respective diagram again shows the characteristic values of two provision processes 47, 48 for each tamping process 9. These spatial profiles provide information about the homogeneity of the track 1, the state of the ballast and the success of compaction.

Especially on track 1 with old ballast ( Fig. 18-20 ) and unsole sleepers, there are often significant and small-scale differences between the storage conditions of the individual sleepers 2. These conditions also affect the condition of the ballast 17 and generally create heterogeneous conditions. It is possible to react to this by specifying changed parameters while the stuffing processes 9 are being carried out. However, the heterogeneity of the old track 1 remains. Therefore, the heterogeneity evaluated on the basis of the characteristic value curves shown serves as a criterion for specifying tamping intervals.

By evaluating the parameters 31-40 for a track section, it is therefore possible to estimate when the next work-through (tamping) of this track section is necessary in order to maintain a satisfactory track position. This provides an indicator for a current classification in the life cycle of track 1. With increasingly shorter tamping intervals, track 1 is nearing the end of its idle time and renovation measures have to be carried out. The present method thus provides parameters 31-40, which are also suitable for comprehensive planning of track maintenance.

Claims (15)

1. A method for compaction of a track ballast bed (5) by means of a tamping unit (7) having sensors comprising two oppositely positioned tamping tools (8) which are coupled in each case via a pivot arm 10 to a squeezing drive 11 and a vibration drive 12 which, actuated with vibrations (13), are lowered into the track ballast bed (5) during a tamping operation (9) and moved towards one another with a squeezing motion (18), characterized in that, for at least one tamping tool (8) of the tamping unit (7), a progression (28) of a horizontal contact force (21) to the ballast (17) acting upon the tamping tool (8) over a path (23, 27) covered by the tamping tool (8) is recorded during a vibration cycle (29) by means of sensors (20, 22, 24) arranged at at least one of the pivot arms (10) and/or the associated tamping tool (8) and that from this at least one characteristic value (31-40) is derived by means of which an evaluation of the tamping operation (9) and/or of a quality of the track ballast bed (5) is carried out.
2. A method according to claim 1, characterized in that the characteristic value (31-40) is prescribed as a parameter for controlling the tamping unit (7).
3. A method according to claim 1 or 2, characterized in that, for evaluation of a ballast condition or a compaction condition of the ballast bed (5), a maximal force (31) acting on the tamping tool (8) during the vibration cycle (29) is derived as a first characteristic value.
4. A method according to one of claims 1 to 3, characterized in that, for evaluation of a compaction condition of the ballast bed (5), a vibration amplitude (32) occurring during the vibration cycle (29) is derived as a second characteristic value.
5. A method according to one of claims 1 to 4, characterized in that, for evaluation of a ballast condition of the ballast bed (5), a start of contact between tamping tool (8) and ballast (17) and a loss of contact between tamping tool (8) and ballast (17) is determined for the vibration cycle (29), and that from this a third characteristic value is derived.
6. A method according to one of claims 1 to 5, characterized in that, for evaluation of a load bearing capacity of the ballast bed (5), an inclination (37) of the progression (28) during a stress phase of the tamping tool (8) is derived as a fourth characteristic value.
7. A method according to one of claims 1 to 6, characterized in that, for evaluation of a ballast condition of the ballast bed (5), an inclination (38) of the progression (28) during a relief phase of the tamping tool (8) is derived as a fifth characteristic value.
8. A method according to one of claims 1 to 7, characterized in that, for determining a degree of utilization, a deformation work (40) performed by means of the tamping tool (8) is derived from the recorded progression (28) as a sixth characteristic value.
9. A method according to one of claims 1 to 8, characterized in that, for determining an overall stiffness of the ballast bed (5), an overall inclination (39) of the progression (28) is derived as a seventh characteristic value.
10. A method according to claim 9, characterized in that the overall inclination (39) is determined by linear regression of the recorded progression (28).
11. A method according to one of claims 1 to 10, characterized in that the progression (28) of the force (21) acting on the tamping tool (8) over the path (23, 27) covered by the tamping tool is recorded for several vibration cycles (29) of a tamping operation (9), that a characteristic value is determined for each of these vibration cycles (29), and that an evaluation procedure takes place by means of a characteristic value progression.
12. A method according to one of claims 1 to 11, characterized in that several squeezing operations (48, 49) are performed at a track location (6), that for each squeezing operation (48, 49) a characteristic value for a vibration cycle (29) or a characteristic value progression for several vibration cycles (29) is determined for evaluation of a compaction condition of the ballast bed (5), and that in the event of non-attainment of a prescribed compaction condition, a further squeezing operation is performed.
13. A method according to one of claims 1 to 12, characterized in that a characteristic value for a vibration cycle (29) or a characteristic value progression for several vibration cycles (29) is determined in each case for several tamping operations (9) at different locations (6) along a track (1), and that from this an evaluation of a spatial development of a compaction result and/or the quality of the ballast bed (5) takes place.
14. A device for performing a method according to one of claims 1 to 13, including a tamping unit (7) having sensors comprising two oppositely positioned tamping tools (8) which are coupled in each case via a pivot arm (10) to a squeezing drive (11) and a vibration drive (12), characterized in that sensors (20, 22, 24) for recording the progression (28) of the horizontal contact force (21) to the ballast (17) acting on the tamping tool (8) over the path (23, 27) covered by the tamping tool are arranged at at least on one of the pivot arms (10) and/or the associated tamping tool (8), that measuring signals (25) of the sensors (20, 22, 24) are fed to an arranged evaluation device (26), and that the evaluation device (26) is designed for determining a characteristic value (31-40) derived from the progression (28).
15. A device according to claim 14, characterized in that at least one force-measuring sensor (20) is arranged in a tamping tool mount (15).

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