GB2622043A - A rail repair device and method - Google Patents

Abstract

An automated portable rail repairing machine 10 for in situ repair of defects in rail track 16. The machine comprising a chassis 12 to which are connected wheels 14 and wherein connected to the chassis are a rail track excavation apparatus arranged to excavate material from a rail track, a rail track welding apparatus arranged to apply material to an excavated part of a rail track, and equipment for precise reprofiling the repaired area. The system may comprise one or more block heaters 20 for heating the rail. The system may comprise two block heaters which extend beyond the excavated section to form a thermal barrier on either side of the repaired section. The excavation apparatus may be a milling machine, such as a CNC milling machine. The machine may further comprise a clamping mechanism. The machine may further comprise a rail track profile measuring system. The machine may further comprise a temperature monitoring system. A method of operation of the machine is also disclosed.

Description

A Rail Repair Device and Method

Field of the Invention

The invention relates to a device for repairing rail track and a method for the same, particularly to an automated machine for the in-situ repair of defects in rail track.

Backaround to the Invention

Due to the nature of use of rail tracks, defects occur in the rails over time This may be due to weather conditions and/or trains passing over the rails and, of course, the quality of the rails themselves Hitherto, in order to repair such defects, a team of people are sent to the location of the defect and repairs are carried out manually These repairs require the team to manually heat the rails using a gas torch, normally a propane powered torch, to heat the rail to around 343 degrees centigrade,primarily to reduce the rate of cooling to ensure desirable microstructure in the heat-affected zone of the repaired area; however, as the heating is a manual process carried out with a gas torch, accurate control of temperature to which rail is heated has proved difficult and impractical. Subsequent to heating the track, the defect is manually ground out using a grinder or gouged out by flame curing. Once the defect has been removed, either a welding torch is employed to fill in the missing section with weld or, in some situations, thermite procedure is used to quickly fill-in the ground section. Once the defect in the rail is filled, the rail needs to be shaped to get the profile close to that of adjacent sections. The shaping is a manual process that is often undertaken using grinding wheels and although quality of the blending operation is strongly dependent on the dexterity of the operator, consistency of results is not often achieved.

The manual use of a gas torch and/or thennite in repair process is time-consuming and raise concerns of safety for the track worker. Furthermore, the profile of the rail track after the repair is complete is often different from that of the rest of the rail, thereby increasing the risk for further damage to the rail from the significantly increased dynamic forces imparted by the wheel as a result of misaligned rail geometry across the repaired area. Similarly, once the excavated section has been filled, uncontrolled, and sometimes rapid, cooling of the rail can result in the formation of martensite, which can weaken the repaired section.

Methods of repairing rails have been previously proposed, for example in EP1878528 (Corus UK Limited) and W02012114083 (Mirage Machines Limited), however, such methods can result in inconsistent repairs with susceptibility to undesirable microstructures. Additionally, the methods can be time-consuming because of the need for the attachment and detachment of tools and parts

Summary of the Invention

Accordingly, the present invention is directed to an automated portable rail repairing machine for in situ repair of defects in rail track, the machine comprising a chassis to which are connected wheels, wherein also the connected to the chassis are: a rail track excavation apparatus arranged to excavate material from a rail track and a rail track welding apparatus arranged to apply material to an excavated part of a rail track.

Thus, a rail track repair machine is provided that can automatically repair, preferably discrete, defects in rail track in situ and has both evacuation apparatus and welding apparatus affixed to the chassis. Such an automated machine can allow for the in-situ repair of defects, for example, once a defect has been identified, the automated rail repair machine of the present invention can be mounted upon the rail track and moved into position over the defect, after which the repair process can be undertaken. The device is able to excavate the defect and then fill-in the excavated section with fresh material, with the finished repair being a close, and potentially near-perfect, match to the desired profile of the track. The automated machine reduces the time required to repair defects and so reduces emissions compared with conventional manual processes while at the same time increasing availability of the track for the purposes for which it was installed.

The device of the present invention creates a safer manner in which defects are repaired and reduces the risks associated with manual excavation and welding processes. The welding may be undertaken by any viable welding process, particularly arc welding processes, for example, flux-cored arc welding or gas metal arc welding. The weld process restores the excavated section in order to provide a better and more consistent repair of rail track, compared with existing methods. Furthermore, the process is more efficient and so reduces the down-time of the rail track. Providing a fully automated process provides consistency over existing techniques.

A processor may control the repair process so that the machine and the repair can be fully automated and controlled precisely through a programmable logic controller with an

executable program.

In order to carry out the repairs accurately, it is advantageous that prior to the repair being undertaken, the machine is fixed in place, relative to the defect. Therefore, the machine may further comprise a clamping mechanism to clamp the machine in a location and hold it securely in place essential for all subsequent operations. Such a clamping mechanism may comprise at least two location securing clamps for securing the machine to the rail track to be repaired, and, preferably, there are four or more clamps. In one arrangement, the clamps may be arranged so that a first clamp, or set of clamps secure the machine onto a first rail track, and a second clamp, or set of clamps, secure the machine onto a second rail track. By clamping the machine in place using a plurality of clamping mechanisms, the machine can be held securely, thereby allowing accurate repairs to the rail track. It is advantageous that the clamps operate simultaneously to secure the machine in place, preferably being controlled by software that can align the clamping. Furthermore, sensors may be provided to ensure that the clamps are operated in a manner to provide a desired angle of the chassis relative to the rail track. The clamping mechanism can allow the chassis to be arranged in a secure position, which can then allow in-situ excavation of identified defects. Thus, secure synchronised multi-point clamping can be employed for precise squareness, thereby ensuring accurate positioning of active equipment heads, such as the welding head and the milling head.

Preferably, the machine further comprises at least one cast block heater, with the cast block heater having a first position and a second position, wherein, when in the second position, the at least one cast block heater is arranged adjacent the rail track in order to heat the same. More preferably, the cast block heaters work in pairs, with each of the pair of cast block heaters being positioned on respective sides of the rail track. The heaters can be moved from a first position, in which they are held away from the rail track, to a second position, wherein they are adjacent the rail track. In the second position, the pair of cast block heaters can heat the rail track from both sides. The cast block heaters preferably extend beyond the defect on both sides of the rail and allow a more controlled heating and cooling of the rail. By controlling the heating and cooling of the rail and the weld repair, the integrity of the finished repair is greater than using a manual process and/or a gas torch. The cast block heaters can be arranged to fit underneath the rail head in order to heat the rail from the underside. Unlike the manual process, the arrangement of the present invention allows the rail head to be accessible during the excavation and repair stages, whilst also being able to maintain more uniform heating of the rail. The extension of the cast block heaters to beyond the length of the area to be repaired allows a thermal barrier to be set up at either end of the repaired area and thereby reduce the rate of cooling within the heat affected zone and ensure the desired microstructure. The control over the heating and cooling of the rail reduces the risk of martensite formation during the repair process.

It is preferred that there are at least two pairs of cast block heaters provided on the machine, one for each of the rails Having two pairs of cast block heaters reduces the need to reposition the heater for each of the rails. The cast block heaters may be powered from a source on the machine, for example. the same power source as that used for the welding process. Alternatively, a separate power source may be provided for the cast block heaters.

Due to the control of the heating and cooling rates that comes with using the cast block heaters of the present invention, repair of more hardenable, premium rail steel grades is possible. Hitherto, such grades cannot be reliably repaired due to the lack of control in the cooling of the post-repair weld material. A low preheat temperature can provide a safety platform to compensate for the wide range of temperatures of rails in track at different times of the year, thereby allowing the machine and system of the present invention to obtain a more consistent finish to repairs, regardless of the environmental conditions, particularly the weather conditions. Thus, the rail may be heated to a temperature of, or less than, 120 degrees centigrade.

Advantageously, a rail track profile measurement system is provided on the machine, and, in one arrangement, the profile measurement system comprises at least two lasers that are arranged to measure the shape and contours of surface of the rail track. The lasers are employed to scan the track and to measure the surface profile thereof, so that the system can create a model, which is preferably, a three-dimensional model of the rail head. Discrete laser measurements can be first computed to derive a smooth transversal profile of the rail and then to project that profile across to the corresponding points measured on the other side of the repaired area. This allows the system to obtain the desired positional movement of the milling cutter to ensure a good blend across the repaired area and adjacent sections. Thus, the profile of the section to be excavated can be modelled and, once the repair process is complete the profile of the repaired length can be matched closely to the modelled profile. Thus, the risk of future defects caused by the surface of the rail being mis-aligned is reduced. It will be appreciated that other measurement and/or scanning arrangements may be employed and/or more than two lasers may be included in the profile measurement system to improve the modelling of the rail head.

It is particularly useful that the machine further comprises a temperature sensor arranged to monitor the temperature of the rail track during the repair process By monitoring the temperature of the rail track during the repair process, the reprofiling of the repaired area can be better executed to achieve the desired near-perfectly blended profile across the repaired length. Furthermore, the welding process can be undertaken at the correct temperatures, rather than over-heating the track, thereby ensuring consistent repair integrity, reducing carbon emissions and making the process more efficient.

The invention extends to a method of repairing a defect in a rail track comprising the steps of: providing rail repair machine as set out herein; positioning the rail repair machine over the defect to be repaired and locking the machine in an appropriate location to repair the defect; excavating the defect area; and welding the excavated section to return the track to a desired profile, which may be substantially the same shape as the sections adjacent the defect.

The method of repairing a defect in a rail track uses the device of the present invention to automatically excavate and weld the track in situ. The relevant parts of the machine may be moved into, and out of, a repair zone, as required, so that they are in the desired position when needed.

It is preferable that the profile of an adjacent track section to the defect is measured prior to the excavation beginning, and the newly welded material can be matched to substantially the same profile as the adjacent section. Furthermore, it is particularly preferable that the profile of the track on both sides of the defect to be repaired is measured to create a three-dimensional template. Thus, the profile measurement system is used, which may comprise lasers, to create a three-dimensional model that the machine can employ to create a desired profile for the finished weld. The laser system enables measurement of the distance to the rail surface and thereby ensure correct stick-out length of the wire and its positioning on the rail surface. Thus, the desired profile can be calculated and matched in order to achieve a high-quality repair. By cutting the weld wire to the required stick-out length, the present invention can account for any changes in rail profile due to welding heat.

It is advantageous that cast block heaters are employed to heat the rail track at the location of the defect, and it may be that the temperature of the rail track is monitored repeatedly during the repair process. Using cast block heaters, that can fit to the profile of the track and preferably can fit to the underside of the rail head, provides and efficient and effective heating mechanism to ensure that the rails are heated to the correct temperature for the repair. The heat can be provided primarily by conduction into the track and this can help to further ensure that the temperature is maintained during the repair process, which may be particularly beneficial in cold environments where the temperature would otherwise drop rapidly upon removal of a gas torch.

In one preferred embodiment, the defect in the rail track is marked prior to the positioning of the rail repair machine over the defect. The defect in the rail can be marked in advance so that the machine of the present invention can be accurately positioned. The marking may be in the form of a substance being applied to the track at the position of the defect, for example white paint. Not only does this allow the machine to be positioned accurately, but it also enables the scanning and profiling of the track to be more easily undertaken by creating a surface upon which the contours may be more accurately identified. The welding gun may be moved in a square weave pattern.

In order improve the quality of the repair, it is advantageous that after weld has been applied, a peening process of the welded layer is undertaken to ensure efficient removal of the slag formed to protect the molten weld pool. This peening process can be important to minimise/eliminate the risk of a stress-raising defect that would subsequently grow under the passage of wheels and lead to transverse rail fracture. Automation of the peening process through the controlled square weave movement can deliver a more thorough removal of slag debris. Additionally, there are benefits of imparting compressive stresses particularly in the intermediate layers during the repair process. In a similar manner to the welding gun, other elements, such as the peening mechanism may follow a square weave pattern or another pattern to ensure that the repair is of high quality, The milling machine can be employed to reprofile the finished repair. Using the milling machine, in combination with the modelled rail head profile, the rail head can be reprofiled to a finish that reduces the risk of future damage to the rail. The resulting repair may be a blended profile across the rail head and the sections adjacent the repaired region.

In one embodiment, the arrangement may be provided with one or more air knives. The air knife, or air knives, may be employed to cool the rail and/or to remove debris. This provides a method of cooling the rail to the required temperature prior to reprofiling in a quick and efficient manner, thereby reducing the repair time.

It will be appreciated that heating of rail track may be undertaken using at least one cast block heater and thus the present invention may extend to a rail track heating device comprising cast block heater. The cast block heater may be as described herein but employed independently from the rail track repair machine. Preferably, the cast block heater is provided with a profile to match, or substantially match the profile of at least a portion of rail track, thereby enabling the track to be heated by placing the cast block heater adjacent the rail to be heated. The cast block heater may be provided with power from a device upon which it is mounted, which may itself be provided with wheels so that it can roll along the tracks.

The present invention may extend to the cast block heater arrangement for heating rail track, and may extend to the positioning of sw-arf trays adjacent the cast block heater arrangement.

Brief Description of the Drawings

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 shows a rail repair machine in accordance with a first embodiment of the present invention, Figure 2 shows a flow chart illustrating an embodiment of the repair process of the present invention; Figures 3a and 3b show the cask block heater arrangement of the present invention in a first and second position, respectively.

Detailed Description of Exemplary Embodiments

The figures show a rail repair machine 10 comprising a chassis 12 upon which various elements are mounted. The chassis 12 is provided with wheels 14 to engage with a rail 16 and allow movement of the machine 10 there along.

The chassis 12 is further provided with clamps that can be activated to secure the machine 10 on the rails 16, thereby restricting, or preventing, movement of the machine 10 relative to the rails 16. Thus, the machine 10 can be held in place relative to the rail 16 whilst a repair is carried out The clamping mechanism comprises four hydraulically operated clamps positioned at different locations upon the chassis. The clamps are synchronised using software to engage the rails and ensure that the machine 10 is centralised and secured on the rails 16.

The synchronisation is undertaken by software to ensure that the clamps are applied equally and accurately to ensure that the machine 10 is positioned securely in place, or that the clamps are applied as needed to align the machine 10 correctly.

Further arranged on the chassis 12 is a cast block heater arrangement 18. In this heater arrangement, two cast block heaters 20 are arranged on respective side of the rail 16. The heaters 20 are shaped to have a profile that follows that of the rail 16 and the underside of the rail head. The cast block heaters 20 have a first position arranged with a gap between the cast block heaters 20 in which the rail 16 sits, and a second position in which the gap between the cast block heaters 20 is reduced, thereby bringing the cast block heaters 20 closer to the respective sides of the rail 16. When in the second position, the cast block heaters 20 heat the rail due to conduction of heat into the rail 16.

Arranged on the sides of the cast block heaters 20 that are distal from the rail 16 are swarf trays 22. The swarf trays 22 are positioned so as to catch any debris or swarf that is generated during the repair process, which may include metal particles or weld material.

By providing swarf trays 22 adjacent the cast block heaters and underneath the rail head in a repair zone, the repair process can be more readily automated and waste material -1 0 -collected to reduce the risk of injury and to increase the efficiency of the repair process. Furthermore, the collected debris may be recycled.

A laser scanning system is provided on the chassis 12 that comprises a pair of lasers that are directed towards the rail in the repair zone, the repair zone being a location within the machine, when in use, at which the defect to be repaired is located. The lasers are arranged so as to be able to scan the surface of the rail head and to measure various parameters of the rail head, for example, the surface shape and/or profile. The scanning system can be used to produce a three-dimensional electronic model of the rail head, including the measured heights and contours of the rail.

A computer numerical control milling machine is arranged on the chassis and is able to be positioned adjacent the defect. The milling machine is provided with multiple cutting edges that can be adjusted. Thus, the cutting edges can be arranged to reduce set up times, extend the tool life and to increase productivity by removing the defect accurately and with a shape that allows a high-integrity weld to be deposited in the repair process. Furthermore, the same milling tool can be used for reprofiling the weld repaired area by software control of the tool in a manner similar to that deployed in computer-numericcontrol milling operations.

Further mounted upon the chassis is a welder. The welder is arranged to be positioned such that when the defect has been excavated by the milling machine, the welding machine can repair the rail track and fill the excavated portion or section with fresh material. The welder is provided with a source of consumable welding wire that is automatically snipped to the desired stick-out length. The weld wire is held in a spool and can be dispensed as required. Advantageously, two wire straighteners are provided that can correct any inconsistencies of wire feed from the spool. Furthermore, the welding gun may be provided with a pre-set welding angle, incorporating a direct connection to the wire feeder. Precise control of wire stick-out length is obtained by using a laser distance sensor that feeds forward the length of weld material required to activate an automatic wire snipper to cut the weld wire to the required stick-out length. Thus, the welder is able to calculate the required stick-out length, by taking account of any change in rail shape that occurs during the heating of the rail before and during the welding process, which may occur due to heating of the rail. Scrap wire can be received in a specifically provided tray for later disposal in an appropriate manner.

The welding gun traverses the rail in a square weave pattern with prescribed and precisely controlled parameters of traverse, step-over distance, and welding speeds. Following completion of deposition of a layer, the deposit is allowed to cool naturally for a short fixed period of time to facilitate detachment of slag. A pneumatically operated peening gun is then traversed over the deposited layer in a similar weave pattern to ensure effective removal of slag. A low-pressure air nozzle is provided such that it can follow the peening gun to deliver a blast of air at high volume and low pressure to blow away slag debris that may remain after the peening operation. The peening gun and air nozzle can be arranged within the spindle of the milling machine and can be controlled by a processor.

The machine 10 is provided with a generator on the chassis 12 that is employed to provide power to the various elements of the machine, including the cast block heaters 20, the scanning system, the welder and the milling machine. Furthermore, a processor is provided to control the various parts of the machine 10 arid to enable the steps of the repair to be carried out in the correct sequence and times. The processor provides precise control of all weld parameters in order to provide a high integrity weld deposit. Various further sensors and elements may be arranged to provide the processor with information on the repair and the repair process.

One or more air knives may be arranged within the machine and directed towards the rail for more rapid cooling down to the desired temperature prior to reprofiling.

As shown in the flow chart of Figure 2, the method of operating the rail repair machine begins with positioning the machine above a defect and using the clamping mechanism to hold the machine securely in place against the rails.

Once the rail repair machine 10 is securely located, a temperature sensor is employed to monitor the rail temperature. As the integrity of the weld repair is strongly influenced by the thermal history of the weld, the machine 10 of the present invention monitors the -12 -temperature of the rail and the weld repair throughout the process. Having measured the temperature of the rails, the lasers of the measurement system are employed to measure the profile of the rail. By measuring the profile of the rail, a three-dimensional model is created to which the finished rail should conform. The lasers are arranged at a known pre-determined angle and the traverse across the rail head taking measurements therealong. Once the profile has been measured, this is stored and is used later to control the movement of the milling cutter to deliver a near-perfect blend of profile across the repaired area.

Excavation of the identified defect can be initiated immediately following measurement of rail profile. However, temperature of rail is measured to establish the start point of monitoring of thermal history through the repair stages The CNC milling machine that is mounted upon the chassis automatically excavates the defect in the rail head. The computer-controlled excavation ensures the shape and dimensions of the excavated section are within set parameters. Thus, the shape and the depth of the excavated portion can be designed to impart the required camber and radii that improve the weld integrity. The CNC milling machine is able to repair defects of up to 100mm long and up to 15mm deep. Whilst it is envisaged that longer and deeper defects could be repaired, for example, defects up to 200mm long and 25mm deep, most repairs are within the aforementioned dimensions. However, the machine can be programmed to repair longer and deeper defects, if necessary.

The cast block heaters 22 are moved from the first position in which the gap between the heaters is greater, to the second position in which the cast block heaters are adjacent and in contact with the rail. As can be seen in Figure 3b, the cast block heaters fit under the rail head in order to heat the rail transversely from both sides and from the underside of the rail head. The cast block heaters 22 are sized to be longer than the section being repaired so that the rail is also heated and maintained at the desired temperature on both sides of the section to be repaired along the axis of the rail. This is a novel approach involving the creation of a thermal barrier immediately adjacent to the edge of the repaired length and thereby slow the rate of cooling within the heat affected zone to ensure the desired pearlitic microstructure. The cast block heaters 22 are powered by the welding generator that is housed on the chassis, thereby removing the need for gas to be -13 -supplied to heat the rails. The engagement of the rail head by the cast block heaters 22 from both sides of the rail permits rapid and more uniform heating to a low pre-soak temperature of 60 to 80 degrees centigrade, although the temperature may, in some cases, by up to 120 or 140 degrees centigrade. The cast block heaters 22 can be retained in place throughout the process, thereby allowing the cooling rate to be accurately controlled.

Furthermore, as the cast block heaters 22 extend axially to each side of the defect, a thermal barrier for heat conduction away from the repair region is also established. It will be appreciate that weld restoration could be undertaken using the process of this invention but without employing any preheat, but this will increase the risk of undesirable hard microstructures. Hence, the low preheat process provides the additional assurance for high integrity repairs.

Once the measured temperature of the rail reaches a value within the specified range of 60t and 80°C and more favourably at the higher end of the specified range, the weld restoration process can be initiated. In preparation, the welding gun is positioned over the wire snipper (17) and the wire extended into the device to permit cutting precisely to the specified wire stick-out length which is an important parameter for the control of weld integrity. Furthermore, this length incorporates the influence of rail distortion resulting from welding heat input.

The welding process comprises deposition of a sufficient number of layers to restore the excavated cavity followed by an additional sacrificial layer as a source of heat input to achieve the desired microstructure in the heat affected zone of the penultimate layer. Thus, in the example of a 10 mm excavation, three restoration layers plus a sacrificial layer are needed to complete the repair. Each restoration layer starts with the snipping of the wire to the prescribed wire stick-out length. This is then followed by positioning of the welding gun at a bottom corner of the excavated cavity and the welding progresses following a square weave path. The width of each traverse across the width of the rail is reduced by a fixed distance to ensure no overflow of molten weld bead. The speed of welding along the traverse and at step over at the end of the traverse are precisely controlled to ensure uniformity of weld bead shape and size.

-1 4 -Once the deposition of a layer is complete, the weld deposit is allowed to cool naturally to allow the slag to detach from the metal deposit. The peening operation is automatically initiated at the end of the prescribed period of natural cooling. Peening follows a square weave pattern similar to the welding gun operation and is followed by a nozzle blowing air at high volume-low flow rate to ensure complete removal any slag layer.

The automated process sequence of wire snipping, square weave welding, square weave peening, and air-blow cleaning is repeated to deliver the number of welding and sacrificial layers prescribed for the excavated depth.

Once the weld is complete, the surface temperature of as welded area is likely to be in excess of 250°C. Prior to finishing the reprofiling of the repaired section of the rail the temperature should be less than 50°C. Therefore, the air knives are repeatedly traversed over the repair area to reduce the temperature. Once the appropriate temperature of the rail is detected, subsequent reprofiling can be undertaken. The air knives may also assist in cleaning the rail and removing debris and/or svvarf that may have accumulated on or around the rail. The debris can be collected in the swarf trays.

The reprofiling may be undertaken by the milling machine Furthermore, the laser scanning system may be used to ensure that the profile of the repaired rail matches the desired profile that is created during the three-dimensional modelling process.

Corrections to the reprofiling may be undertaken if the rail head is scanned after the weld process and the profile is not substantially in conformity with the modelled profile.

It is envisaged that the rail track repair machine is transported to the repair site on board a specialist maintenance train, a suitable road-rail vehicle or it may be provided with its own propulsion system. Preferably, the machine can be accurately positioned over an identified defect. For maximum flexibility of deployment, a road-rail vehicle suitably modified to house the discrete defect repair machine, associated power source, hydraulic and pneumatic equipment, and the process controller is the preferred mode for transporting the repair machine to work site.

The temperature sensor can be used to measure temperatures at selected locations through the various process states to ensure the integrity of the repair.

-15 -The peening gun and air nozzle can be arranged within the spindle of the milling machine and can be controlled by a processor.

The air knife, or knives, and/or cast block heater arrangement may be employed independently of the rail repair machine

Claims (17)

1. -16 -Claims An automated portable rail repairing machine for in situ repair of defects in rail track, the machine comprising a chassis to which are connected wheels and wherein further connected to the chassis are: a rail track excavation apparatus arranged to excavate material from a rail track; and a rail track welding apparatus arranged to apply material to an excavated part of a rail track.
2. A rail repairing machine according to claim 1, wherein the machine further comprises a clamping mechanism to clamp the machine in a location and hold it securely in place.
3. 3. A rail repairing machine according to claim 2, wherein at least two location securing clamps for securing the machine to the rail track to be repaired.
4. 4. A rail repairing machine according to any one of claims 1 to 3, wherein the machine further comprises at least one cast block heater, with the cast block heater having a first position and a second position, wherein, when in the second position, the at least one cast block heater is arranged adjacent the rail track in order to heat the same.
5. 5. A rail repairing machine according to claim 4, wherein at least two cast block heaters are provided and, when in the second position, they engage both sides of the rail track.
6. 6. A rail repairing machine according to claim 5, wherein the cast block heaters extend beyond the excavated section to create a thermal barrier on either side of the repaired section.
7. A rail repairing machine according to any preceding claim, wherein a rail track profile measurement system is provided on the machine.
8. -17 -A rail repairing machine according to claim 7, wherein the profile measurement system comprises at least two lasers that are arranged to measure the shape and contours of surface of the rail track.
9. A rail repair machine according to any preceding claim, wherein the machine further comprises a temperature sensor arranged to monitor the temperature of the rail track during the repair process.
10. 10. A method of automatedly repairing a defect in a rail track comprising the steps of: providing rail repair machine according to any preceding claim; positioning the rail repair machine over the defect to be repaired and locking the machine in an appropriate location to repair the defect; excavating the defect area; and welding the excavated section to return the track to substantially the same shape as the sections adjacent the defect.
11. 11. A method according to claim 10, wherein the profile of an adjacent track section to the defect is measured prior to the excavation beginning, and the newly welded material is matched to substantially the same profile as the adjacent section.
12. 12. A method according to claim 11, wherein the profile of the track on both sides of the defect to be repaired is measured to create a three-dimensional template.
13. 13. A method according to any one of claim 10 to claim 12, wherein cast block heaters are employed to heat the rail track at the location of the defect.
14. 14. A method according to claim 13, wherein the rail is heated to a temperature of less than 140 degrees centigrade.
15. 15. A method according to any one of claims 10 to 14, wherein the temperature of the rail track is monitored repeatedly during the repair process.
16. 16 A method according to any one of claims 10 to 15, wherein the defect in the rail track is marked prior to the positioning of the rail repair machine over the defect.
17. 17. A method according to any one of claims 10 to 16, wherein after weld has been applied, a peening process is undertaken on the layer of weld material.