Method and track-laying machine for tamping sleepers of a track

Abstract

Proposed is a method for tamping sleepers (9) of a track (3) by means of a tamping assembly (6), the tamping tools (12) of which are plunged into a ballast bed (11) and squeezed toward one another, with the condition of the ballast bed (11) being determined. Here, a setting value (E) for a squeeze pressure (pB) for pressurizing squeeze cylinders (16) of the tamping assembly (6) is automatically specified on the basis of the determined condition of the ballast bed (11). It is thus possible for the squeeze pressure (pB) to be adapted during every tamping operation to the conditions in the ballast bed (11). The invention also relates to a system for tamping sleepers of a track.

Description

[0001] Method and track construction machine for tamping sleepers of a track

[0002] The invention relates to a method for tamping sleepers of a track using a tamping unit whose tamping tools are immersed in a ballast bed and positioned close to one another, whereby the nature of the ballast bed is determined. Furthermore, the invention relates to a corresponding system for carrying out the method.

[0003] A generic method is known from AT 520698 A1. It uses a sensor to detect the load on the tamping unit in addition to determining the quality of a ballast bed. Specifically, a penetration force is determined during the penetration process of a tamping tool into a ballast bed. A load-time curve derived from this data forms the basis for evaluating the ballast quality.

[0004] AT 521850 A1 also uses the immersion process of a tamping tool to obtain conclusions about the condition of a ballast bed. This involves a controlled lowering movement of the tamping tools, with at least one variable processed in the control loop being fed to an evaluation device for deriving a characteristic value for the ballast bed.

[0005] AT 520056 A1 discloses another method for determining the condition of a ballast bed. A force transmitted to the track ballast due to a horizontal vibration movement of tamping tools is recorded in order to draw conclusions about the condition of the ballast bed. AT 521798 A1 discloses a method for determining the condition of a ballast bed using a working unit for ballast compaction, wherein the working unit comprises an electric drive. A ballast bed characteristic is derived from at least one operating variable of the electric drive using an evaluation device.

[0006] The invention is based on the object of enabling improved operation of the tamping unit based on the method of the type mentioned above. Furthermore, it is an object of the invention to provide a correspondingly improved system for tamping sleepers on a track.

[0007] According to the invention, these objects are achieved by the features of independent claims 1 and 10. Dependent claims specify advantageous embodiments of the invention.

[0008] [Claim 1] On the basis of the determined nature of the ballast bed, a setting value for an application pressure to act on the application cylinders of the tamping unit is automatically specified. The application pressure is an important value in asynchronous constant pressure tamping, in which opposite tamping tools are tamped with the same pressure to one another with regard to a sleeper to be tamped. The same pressure is produced by a joint activation of the application cylinders assigned to the tamping tools. During a specified tamping time, different reaction forces of the ballast on the respective tamping tool may lead to different tamping paths. The specified tamping time and the set application pressure are important values ​​for influencing the compaction quality of the ballast. Both values ​​are selected depending on the local conditions at the section of track to be tamped.Of key importance here is the current condition of the ballast bed. Information about the condition of the ballast bed can include, in particular, information about a grain size, a fines content, a degree of compaction, a degree of contamination, in particular a degree of vegetation growth, and / or ballast bed stiffness. The condition can also include information about a layer thickness of the track ballast, in particular about a fill level relative to the underside of a track sleeper.

[0009] In particular, the nature of the ballast bed is understood to mean at least one property that is crucial for track operation. Of particular importance are those properties relating to the load-bearing capacity, stiffness, and / or damping characteristics of the ballast bed. These range from a relatively loose ballast bed at the start of track construction (new track laying, soft ballast bed) to a heavily contaminated and compacted ballast bed towards the end of a maintenance period (hard ballast bed). In the latter case, a significantly higher ballast pressure is required to shift ballast grains into a new, compacted structure during the ballast setting process.

[0010] Until now, it was the responsibility of an operator to set a suitable tamping pressure based on foreseeable influencing factors. With the method according to the invention, the tamping pressure is automatically specified depending on the condition of the ballast bed determined before the tamping tool is tamped. This makes it possible to adapt the tamping pressure to the conditions of the ballast bed during each tamping process. Typically, an adjustment takes place in a range of 8 MPa to 12 MPa (80-120 bar), which generally results in a tamping force of 3 kN to 12 kN at the free end of the respective tamping tool (pick plate).

[0011] The automatic setting of the tamping pressure depending on the ballast bed conditions ensures consistent tamping quality. The risk of sleeper displacement is eliminated. Furthermore, the demands placed on the operator are reduced. The automatic tamping pressure system according to the invention forms a subsystem of a partially or fully autonomously operating track maintenance machine.

[0012] [Claim 2] In a further development of the method, the setting value of the auxiliary pressure is specified as a proportion of the available system pressure of a hydraulic system coupled to the tamping unit. Pressure chambers of the auxiliary cylinders are connected to the hydraulic system via servo or proportional valves. As a rule, a pressure reduction in a rod-side pressure chamber leads to an auxiliary movement being carried out. A pressure reduction in a piston-side pressure chamber causes the auxiliary cylinder to return to its original position. To generate maximum auxiliary pressure, the rod-side pressure chamber is made almost pressureless, so that the entire system pressure is present in the piston-side pressure chamber as auxiliary pressure. The setting value is 100% of the system pressure.To reduce the auxiliary pressure below 100% of the system pressure, the piston-side pressure chamber and / or the rod-side pressure chamber are subjected to reduced system pressure using the servo or proportional valves. The current auxiliary pressure results from the pressure differences in the two pressure chambers, taking into account the ratio of the piston area to the annular area of ​​the respective auxiliary cylinder.

[0013] [Claim 3] Advantageously, the setting value is displayed in an output device. This allows an operator to monitor the specification and make adjustments if necessary. For example, the setting value is further reduced during a new track layout if only a minimal track lift is planned at the current track location during the tamping process. In addition, the setting value is logged for each tamping process so that the tamping results can be traced later.

[0014] [Claim 4] To further improve the method, during a lifting and tamping process of the track the setting initially predetermined on the basis of the ballast bed condition is automatically adjusted as a function of a lifting value and / or a tamping time and / or a number of tamping cycles. This further increases the degree of automation. The setting is adjusted in such a way that with each tamping process sufficient ballast is pushed into a cavity created by the lifting process under the respective sleeper. The vibrating tamping tools cause the ballast pushed under the sleeper to be compacted. The tamping process should be finished as soon as the optimum compaction of the ballast is achieved.The relationship between the determined ballast quality, the tamping pressure and time, as well as the lifting value, is preferably determined empirically before setting the automatic tamping pressure setting for the respective tamping unit type. If optimal compaction cannot be achieved with one tamping process, another tamping cycle is performed at the same track location. In such a case, the number of tamping cycles is also taken into account when specifying the setting.

[0015] [Claim 5] A preferred control method is one in which the setting variable is fed to a control device of the tamping unit, wherein the auxiliary cylinders are controlled by the control device in accordance with the setting variable. For example, servo or proportional valves are controlled, by means of which the auxiliary cylinders are connected to a hydraulic system.

[0016] [Claim 6] Advantageously, a control system is provided in which the tamping pressure is automatically adjusted during a tamping process as a function of a detected movement variable of the tamping tool and / or a reaction force acting on the tamping tool. This optimized method ensures that the tamping pressure specified with the setting variable leads to the desired tamping effect in the ballast bed. For example, the tamping pressure is increased if a localized clumping of the ballast under a sleeper slows down the tamping movement. In particular, the tamping speed and / or the maximum dynamic reaction force are recorded during the tamping process.

[0017] The latter occurs as a result of a vibration movement superimposed on the adjustment movement. The dynamic reaction force is greatest when the vibration direction coincides with the adjustment direction. Following this compaction phase, a vibration cycle is followed by a release phase with a vibration direction opposite to the adjustment direction.

[0018] [Claim 7] In an advantageous embodiment of the method, to determine the condition of the ballast bed, a measured variable correlating with a penetration force is recorded during an immersion process of the tamping tools into the ballast bed, the setting value for the tamping pressure being derived from the measured variable. In this way, immediately before a tamping process at the currently processed track section, the ballast bed condition is recorded by a measuring process during the immersion of the tamping tools into the ballast bed. The automatic tamping pressure setting reacts immediately to suddenly changing conditions of the ballast bed.

[0019] A preferred parameter for ballast categorization is the determined penetration force of the tamping tools. This is calculated from the resulting force of a lowering cylinder, which is used to lower the tamping tools into the ballast bed. Key factors here are a lowering pressure, a counterpressure, a piston area, and an annular area of ​​the lowering cylinder. Furthermore, a change in momentum resulting from the acceleration and mass of the lowered components of the tamping unit must be taken into account.

[0020] [Claim 8] To improve the quality of the process, several measured values ​​of the measured variable are recorded at different measuring times during a dipping process in order to derive the setting variable. The basis for determining the ballast bed condition is thus the reaction curve of the ballast bed to the vertically moving tamping tool. The result is more meaningful than a single measurement per dipping process.

[0021] For example, an average, a weighted, or a maximum sinking force can be determined from a penetration force curve. Based on the recorded results, the ballast bed is categorized (e.g., low penetration force, medium penetration force, high penetration force).

[0022] In particular, a quality index can correlate with an energy that is required to move at least one of the tamping tools, in particular to the maximum penetration depth, into the ballast bed. The penetration energy can be determined as the integral of a vertical driving force acting on the at least one tamping tool over the path, in particular the vertical path, that the tamping tool travels in the ballast bed. A particularly meaningful quality index results from the quotient of the penetration energy and a maximum penetration depth. The resulting quality index is thus largely independent of the respective penetration depth of the tamping tools.

[0023] In particular, the pressure curve of the lowering pressure and a measured trajectory of the lowering movement of the lowered unit components - essentially a tool carrier with the tamping tools and the tool drives - are used to automatically specify the auxiliary pressure.

[0024] [Claim 9] In a further development of this method, particularly during the initial processing of a track for several tamping operations, measured values ​​of the measured variable are recorded in order to evaluate them jointly and thus determine the condition of the ballast bed. In this way, the measured data from previous tamping operations, in particular measured data from the lowering movement and the setting movement, are used to adjust the setting pressure for a current tamping operation. This ensures that the condition of the ballast bed is correctly detected even when disruptive influences affect individual measuring operations.

[0025] [Claim 10] The system according to the invention for tamping sleepers of a track comprises a tamping unit with tamping tools that can be immersed in a ballast bed and adjusted relative to one another, and is designed to determine the nature of the ballast bed, wherein a parameter for the nature of the ballast bed is fed to an evaluation device for deriving a setting value for a tamping pressure for actuating tamping cylinders of the tamping unit. Thus, a categorization of the ballast bed recorded in the system serves to automatically adjust the tamping pressure. This increases process reliability and relieves the burden on an operator of the tamping unit.

[0026] The invention is explained below by way of example with reference to the accompanying figures. They show schematically:

[0027] Fig. 1 System with a moving on a track

[0028] Track construction machine for tamping sleepers on the track;

[0029] Fig. 2 Tamping unit of the track construction machine;

[0030] Fig. 3 Hydraulic circuit diagram for controlling an auxiliary cylinder of the tamping unit. The system 1 shown in Fig. 1 comprises a track construction machine 2 for tamping a track 3. By way of example, the track construction machine 2 is designed as a cyclically operating tamping machine, with a machine frame 5 supported on rail carriages 4, on which a tamping unit 6 and, in front of it in a working direction 7, a lifting and straightening unit 8 are arranged. Any other track construction machine 2 equipped with a tamping unit 6 can also be used to carry out the method according to the invention.

[0031] Essentially, the invention relates to a tamping process in which a track grid formed from sleepers 9 and rails 10 fastened thereon is fixed by means of the tamping unit 6 in a position lifted from a ballast bed 11 and optionally directed laterally. Fixing is carried out by tamping tools 12 arranged on the tamping unit 6 first immersing into the ballast bed 11 on both sides of the sleeper 9 currently to be tamped. By means of a subsequent positioning movement 13, ballast grains are pushed under the sleeper 9 and compacted. A vibrating movement 14 of the tamping tools 12 during immersion and positioning facilitates the displacement of the ballast grains. Preferably, a higher vibration frequency (e.g. 45 Hz) is selected for the immersion process than for the positioning process (e.g. 35 Hz).

[0032] As a rule, the opposing tamping tools 12 are designed as oscillating levers and mounted on a common tool carrier 15 (Fig. 2). Upper lever arms of the tamping tools 12 are connected to a vibration drive 17 via auxiliary cylinders 16. In another embodiment, the vibration movement 14 is generated by the auxiliary cylinders 16 by moving hydraulic fluid back and forth at the vibration frequency between a piston-side pressure chamber 18 and a rod-side pressure chamber 19. Tamping picks 20 for immersion into the ballast bed 11 are attached to the lower lever arms of the tamping tools 12.

[0033] The actuating movement 13 of the respective actuating cylinder 16 is effected by applying an actuating pressure p B According to the invention, this auxiliary pressure p B based on the determined nature of the ballast bed 11.

[0034] In one variant of the invention, the condition of the ballast bed 11 is recorded during a separate measuring run prior to the track processing carried out by the track construction machine 2. This preliminary recording is carried out by the track construction machine 2 itself or by another component of the system 1, in particular by a measuring vehicle 21 that travels along the track 3 in front of the track construction machine 2. For example, the track construction machine 2 or the measuring vehicle 21 comprises a measuring device 22 for the contactless detection of the ballast bed 11.

[0035] In particular, the measuring device 22 has at least one transmitting unit for emitting an electromagnetic primary radiation into the ballast bed 11 and at least one receiving unit for detecting a secondary radiation caused by the primary radiation and reflected from the ballast bed 11, wherein the receiving unit is spaced apart from the transmitting unit. The transmitting frequency is preferably in a range from 1 MHz to 5000 MHz, in particular between 400 MHz and 600 MHz. By a

[0036] Evaluation of the recorded secondary radiation is the

[0037] The nature of the ballast bed 11 can be determined. In particular, the primary radiation is emitted at a single transmitting position and the secondary radiation is detected at several detection positions. In this way, a plurality of measurement signals are detected which correlate with the nature of the ballast bed 11. The distance between the transmitting unit and the at least one receiving unit enables radiation to propagate in the ballast bed 11 without being shadowed by a sleeper 9 or a rail 10. This also allows the quality of the ballast beneath the respective sleeper 9 and the respective rail 10 to be detected. Simultaneously with the measurement signal detection, a position detection takes place, for example by means of a GNSS antenna 23.

[0038] Data indicating the condition of the ballast bed 11 linked to a measurement position 25 on track 3 are sent via a mobile radio network 24 to a system center 26 and stored in a database 27. For subsequent track processing, these data are transferred to an evaluation device 28 of the track-laying machine 2. If data has been previously acquired by the track-laying machine 2, they are immediately stored in the evaluation device 28. Transmission to the system center 26 serves for documentation purposes if necessary.

[0039] A current position is determined by means of a GNSS antenna 23 arranged on the track construction machine 2 in order to assign the corresponding data on the condition of the ballast bed 11 to a current working position 29 of the tamping unit 6. When the measuring device 22 is arranged on the track construction machine 2, the spatial assignment is carried out in particular via a distance measuring device 30, in particular via a rotary encoder arranged on one of the rail bogies 4. In a preferred embodiment of the invention, the condition of the ballast bed 11 is determined by means of the tamping unit 6 during an immersion process of the tamping pick 20. In this case, a penetration force F E correlating measured value from which the condition of the ballast bed 11 is determined. The penetration force F E results from a resulting cylinder force F za lowering cylinder 31 and a change in the momentum of the lowered masses. To record corresponding measurement signals, pressure sensors 32 are arranged on the lowering cylinder 31 to measure the pressures in the cylinder pressure chambers, and an acceleration sensor 33 is arranged on the tool carrier 15.

[0040] Preferably, several measured values ​​are recorded at different measuring times or continuous measured values ​​are recorded during an immersion process. This allows an average penetration force F E which correlates to a high degree with the nature of the ballast bed 11 .

[0041] A spatial assignment to the position on track 3 is not necessary because the further steps of the method according to the invention take place immediately thereafter at the same location. The working position 29 corresponds to a current measuring position 25'. This also applies if the measurements from several consecutive tamping processes are used to determine the condition of the ballast bed 11.

[0042] Based on the determined properties of the ballast bed 11, a setting value E for the auxiliary pressure p B for applying the auxiliary cylinders 16 is automatically specified. For example, an allocation scheme is stored in the evaluation device 28, from which the auxiliary pressure values ​​assigned to different characteristic values ​​are derived. As a characteristic value of the ballast bed 11, for example, an average penetration force F recorded during the current immersion process of the tamping pick 20 is EIf this average penetration force F E below 25 kN, the ballast bed 11 is categorized accordingly (low penetration force) and an additional pressure p B of 8 MPa . At an average penetration force F E In a range of 25 kN to 45 kN, for example, an additional pressure p B of 10 MPa . If the average penetration force F E at a value above 45 kN, an additional pressure p B of 12 MPa .

[0043] In addition to classifying the ballast bed properties into discrete categories, the measured values ​​can also be continuously applied to the auxiliary pressure p B The setting value E or the auxiliary pressure p B as a continuous function 34 of a property measurement, in particular the penetration force F E, stored in the evaluation device 28. By means of a corresponding function 34, the setting variable E is automatically determined and specified to a control device 35 of the tamping unit 6.

[0044] In addition, 28 additional parameters can be set in the evaluation device to adjust the auxiliary pressure p B These are, for example, a lifting value H, by which the track grid is lifted at the current location by means of the lifting and straightening unit 8, and / or a specified setting time t B , which specifies the duration of a tamping operation, and / or a number A of tamping interventions at the same track section. Multiple tamping interventions with a specific number A are required, for example, if a specified limit of the lifting value H is exceeded.

[0045] During a backfilling check, as described in AT 524861 A4, the number A of tamping interventions is automatically specified. After each backfilling operation, the backfilling of the cavity beneath the tamped sleeper 11 is monitored by means of a recorded backfilling speed, with insufficient backfilling of the cavity resulting in an automatic repetition of the tamping operation.

[0046] In addition, measurement data of the positioning movement such as the positioning speed and / or a maximum dynamic reaction force F R be used to set the auxiliary pressure p B during the adjustment movement. A movement and / or force measuring sensor 36 arranged on the respective tamping tool 12 provides a corresponding measurement signal. The measurement data is then fed back to the control device 35, resulting in a control of the adjustment pressure p B during the provisioning process.

[0047] Fig. 3 shows a preferred arrangement for adjusting the auxiliary pressure p B by means of two control valves 37, which are designed as 3 / 3-way valves. Each auxiliary cylinder 16 is connected to a hydraulic system via such control valves 37. This system comprises a hydraulic pump, which pressurizes a hydraulic medium with a predetermined system pressure, as well as a tank and, if necessary, an oil cooler, an oil filter, etc.

[0048] In the illustrated passive center position (valve rest position) of the respective control valve 37, a valve spool is held in position by means of two return springs. A spring force acts on each side of the valve spool, so that there is no connection between a system pressure connection 38 and a tank discharge connection 39 on the one hand, and a pressure chamber connection 40 on the other. The corresponding auxiliary cylinder 16 is blocked.

[0049] By means of a control signal from the control device 35, the respective control valve 37 is moved from the passive central position into a position proportional to the control signal by the control element located on one side pressing against the spring force of the return spring located on the opposite side.

[0050] The switching state of the valve spool to the left of the center position connects the pressure line connection 38 to the respective pressure chamber connection 40, thereby enabling the flow of the hydraulic medium toward the lower pressure level. The connection to the tank discharge connection 39 remains interrupted.

[0051] The valve spool position to the right of the center position connects the respective pressure chamber 18, 19 to the hydraulic system tank, resulting in a flow of hydraulic fluid toward the lower pressure level. In this case, the connection to the system pressure port 38 remains interrupted.

[0052] Pressure sensors 32 are fluidically connected to the piston-side pressure chamber 18 and the rod-side pressure chamber 19. These measure the pressure in the respective pressure chamber 18, 19 and convert it into an electrical signal that can be detected by the control device 35. A displacement sensor 41 is arranged in the vicinity of the respective auxiliary cylinder 16. A measured position signal is input into the control device 35 and processed, from which the position of the piston 42 in the respective auxiliary cylinder 16 can be deduced.

[0053] The control valves 37 are controlled taking into account the measuring signals in such a way that the desired supply pressure p B according to the specified setting value E. A respective pressure can be set in each pressure chamber 18, 19 via the position of the valve slides and the resulting proportional connections of the pressure chambers 18, 19 with the system pressure connection 38 and the tank discharge connection 39. Specifically, the supply pressure p B from the pressure in the piston-side pressure chamber 18 minus the pressure in the rod-side pressure chamber 19, taking into account the ratio between the piston area and the annular area. The piston area of ​​the piston 42 defines the piston-side pressure chamber 18, and the annular area of ​​the piston 42 defines the rod-side pressure chamber 19.

[0054] Advantageously, the resulting auxiliary pressure p Bas a function of an existing system pressure, for example, as a percentage of the system pressure. A corresponding output device 43 is arranged in the field of vision of an operator, thereby enabling continuous monitoring. If necessary, the value is adjusted by the operator via an input device 44 in order to take into account aspects independent of the nature of the ballast bed 11. Further adjustment options for the auxiliary pressure p B are achieved through the use of digital valves or through a variable system pressure. Furthermore, different pressure levels can be provided in the hydraulic system. Alternating the connection of the respective auxiliary cylinder 16 to one of these pressure levels results in a corresponding adjustment of the auxiliary pressure p B .

Claims

Patent claims 1. Method for tamping sleepers (9) of a track (3) by means of a tamping unit (6), the tamping tools (12) of which are immersed in a ballast bed (11) and positioned relative to one another, wherein the nature of the ballast bed (11) is determined, characterized in that on the basis of the determined nature of the ballast bed (11) a setting value (E) for a positioning pressure (p B ) for actuating auxiliary cylinders (16) of the tamping unit (6) is automatically specified.

2. Method according to claim 1, characterized in that the setting variable (E) is specified as a proportion of an available system pressure of a hydraulic system coupled to the tamping unit (6).

3. Method according to claim 1 or 2, characterized in that the setting variable (E) is displayed in an output device (43).

4. Method according to one of claims 1 to 3, characterized in that during a lifting and tamping process of the track (3) the setting value (E) is adjusted as a function of a lifting value (H) and / or a setting time (t B ) and / or a number (A) of stuffing cycles is automatically adjusted.

5. Method according to one of claims 1 to 4, characterized in that the setting variable (E) is fed to a control device (35) of the tamping unit (6) and that the auxiliary cylinders (16) are controlled by means of the control device (6) in accordance with the setting variable (E).

6. Method according to one of claims 1 to 5, characterized in that the supply pressure (p B ) during a setting process depending on a detected movement variable of the stuffing tool (6) and / or a reaction force (F R ) is automatically adjusted.

7. Method according to one of claims 1 to 6, characterized in that for determining the condition of the ballast bed (11) during an immersion process of the tamping tools (12) into the ballast bed (11), a force applied with a penetration force (F E ) correlating measured variable is recorded and that the setting variable (E) for the auxiliary pressure (p B ) is derived.

8. Method according to claim 7, characterized in that the condition of the ballast bed (11) is determined on the basis of several measured values ​​of the measured variable at different measuring times during the immersion process and the setting variable (E) is derived therefrom.

9. Method according to claim 7 or 8, characterized in that measured values ​​of the measured variable are recorded during several tamping operations and the condition of the ballast bed (11) is determined therefrom.

10. System (1) for tamping sleepers (9) of a track (3) by means of a tamping unit (6) with tamping tools (12) which can be immersed in a ballast bed (11) and can be positioned relative to one another, wherein the system (1) is designed to determine the condition of the ballast bed (11), characterized in that a parameter for the condition of the ballast bed (11) of a Evaluation device (28) for deriving a setting value (E) for a control pressure (p B ) for actuating auxiliary cylinders (16) of the tamping unit (6).

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