Technical Field The present invention relates to the polyurethane field, especially a method for cutting polyurethane railway track bed, an equipment for implementing the method and the use thereof.

Background Art Railway track bed, which is a ballast layer above the road base and below rail and sleeper, is a base of railway frame. The railway track bed supports rail and sleepers, equally distributes the heavy train load from the rail and the sleepers onto the road base, reduces the distortion of the road base and guarantees the safety of the transportation.

To reduce the heavy load and impact on the ballast bed caused by high speed train or heavy haul train, polyurethane material can be poured or sprayed into the interspace among the ballasts of the railway track bed. This method can solidify the ballasts, reduce the probability of ballast crashing, shifting, cracking and changing into sand, slow the distortion of the track bed, and extend the maintenance cycle and serving lifetime of the track bed.

However, up to now, when the polyurethane railway track bed is broken or the service life of the polyurethane railway track bed expires, it is still a big problem to cut and recycle the polyurethane railway track bed efficiently.

In the prior art, there are several methods for cutting and recycling the polyurethane railway track bed. For example, diamond saw can be used to cut the polyurethane railway track bed, however, the diamond saw may damage the sleepers and rail, due to the fact that the polyurethane railway track bed is directly contacted with the sleepers and no flat cutting area can be applied. In addition, the diamond saw will cause big noise and heavy abrasion when it works. The diamond saw can not be used to cut a polyurethane railway track bed with a thickness of 350 mm entirely, because the cutting thickness of the diamond saw is limited, normally 30-50mm.

For another example, a manual impact hammer powered by air compressor can be used to cut polyurethane railway track bed. However, this method is not suitable for industrial scale operation, because this method requires manual operation of the impact hammer, and causes heavy work-load and high noise.

Further more, a strong polar solvent can be used to remove the polyurethane material in the polyurethane railway track bed, by dissolving or decomposing the polyurethane. However, this method will generate a lot of chemical waste and pollute the environment.

Contents of Invention

The objective of the present invention is to provide a method for cutting polyurethane railway track beds. According to an embodiment of the present invention, the method comprises a step of ejecting a water jet stream through a nozzle onto a surface of a polyurethane railway track bed to cut the polyurethane railway track bed, wherein the pressure of the water jet stream is 10 to 600 MPa, and the diameter of the nozzle of the jet for ejecting the water is 0.1 to

1.0 mm.

Preferably, the pressure of the water jet stream is 30-600 MPa, and the distance between the nozzle of the jet to the polyurethane material is l - 12cm.

Preferably, the water jet stream comprises one or more abrasive materials, and the abrasive materials can be selected from the group consisting of silicon dioxide, alumina, garnet, and mixtures thereof; the granularity of the abrasive material is preferably 50- 120 mesh. Preferably, the pressure of the water jet stream comprising abrasive material is 10-l OOMPa, the diameter of the nozzle of the jet is 0.4-1. Omm, and the distance between the nozzle of the jet to the polyurethane material is l -12cm.

Preferably, the jet has a protector (protecting device) for preventing the water jet stream from impacting a rail and/or a sleeper. The length of the protector provided in the present invention is preferably from 1 -20 cm; the outer diameter of the protector is preferably from 1 -15 cm; the thickness of the protector is preferably from 1 -15 mm, most preferably from 2- 12 mm. The material of the protector provided in the present invention can preferably be selected from the group consisting of metal material, rubber material, engineering plastics, and their mixtures.

Another obj ective of the present invention is to provide an equipment for cutting polyurethane railway track beds. According to an embodiment of the present invention, the equipment comprises one or more devices for ejecting water, wherein the device for ejecting water comprises a protecting device for preventing the water jet stream from impacting a rail and/or a sleeper.

In the present invention, the method for cutting polyurethane railway track bed comprises the step of spraying a water jet stream onto a surface of the railway track bed to cut the polyurethane material comprised in the polyurethane railway track bed. It is good for the environment to use the method provided in this invention, because no toxic substance or steam will be generated. In addition, due to the cooling properties of the water, no overheat effect will appear in the cutting area damaging the steel rail, fastener or mat in the cutting process. Furthermore, the invention provides an equipment for cutting polyurethane railway track bed, wherein the equipment can be used to cut the polyurethane railway track bed and prevent the water jet stream from impacting a rail and/or a sleeper.

Description of the Figures The figures are used to further describe the embodiments and methods disclosed in the present invention. The description of the figures is demonstrative but not restrictive. Figure 1A is a sketch map of a method for cutting polyurethane railway track bed in accordance with one embodiment of the invention.

Figure IB is a sketch map of an equipment for cutting polyurethane railway track accordance with one embodiment of the invention.

Figure 1C is a section map of Figure 1A along the direction of the sleeper.

Figure 2A is a sketch map of an equipment for cutting polyurethane railway track bed in accordance with one embodiment of the invention.

Figure 2B is a sketch map of a method for cutting polyurethane railway track bed in accordance with one embodiment of the invention by using the equipment disclosed in the Figure 2 A.

Figure 3A is a sketch map of a method for cutting polyurethane railway track bed in accordance with one embodiment of the invention.

Figure 3B is a sketch map of an equipment for cutting polyurethane railway track bed in accordance with one embodiment of the invention.

Figure 3C is a section map of Figure 3A along the direction of the sleeper.

Figure 4A is a sketch map of an equipment for cutting polyurethane railway track bed in accordance with one embodiment of the invention. Figure 4B is a sketch map of a method for cutting polyurethane railway track bed in accordance with one embodiment of the invention by using the equipment disclosed in the Figure 4A.

Specific Mode for Carrying Out the Invention

According to the method provided in the present invention, a water jet stream is ejected onto a surface of the polyurethane railway track bed to cut the polyurethane railway track bed, wherein the water pressure is 10-600 MPa, the diameter of the water jet nozzle is 0.1 -1.0mm.

The polyurethane railway track bed is a polyurethane railway track bed comprising ballast and polyurethane, and it also can be a railway track bed wholly comprising polyurethane.

The density of the polyurethane material is preferably 20- 1200 kg/m ³ . The hardness of the polyurethane material relates to four hardness units from low to high (Asker C, Shore A, Shore B and Shore D), and the hardness of the polyurethane material is preferably from 5 Asker C to 90 Shore D. The tensile strength of the polyurethane material is preferably 0.2 to 60 MPa.

The distance between the water jet nozzle to the polyurethane material is preferably from 1 to 12cm.

The water of the jet stream is preferably pure water, but can also contain abrasive materials.

The abrasive material is preferably selected from, but not limited to, the group consisting of silicon dioxide, alumina, garnet, and mixtures thereof. The abrasive material has a granularity of 50-120 mesh. _r

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By using pure water, the pressure of the water jet stream is preferably 30-600 MPa, and the diameter of the water jet nozzle is 0.1 -1.0 mm; most preferably, the pressure of the water jet stream is 30-150 MPa, and the diameter of the water jet nozzle is 0.1 -1.0 mm.

By using water containing abrasive materials, the pressure of the jet stream is 10-100 MPa, the diameter of the jet nozzle is 0.1 -1.0 mm; preferably, the pressure of the jet stream is 10- 30 MPa, the diameter of the jet nozzle is 0.1 -1.0 mm; most preferably, the pressure of the jet stream is 35-100 MPa, and the diameter of the jet nozzle is 04-1.0 mm.

If the pressure of the jet stream (for pure water 250-600 MPa; for water containing abrasive material 35-100 MPa), the water jet stream will not only cut the polyurethane material comprised in the polyurethane railway track bed, but will also cut the ballast comprised in the polyurethane railway track bed. Both the cut ballasts and the cut polyurethane material can be carried away and sent to an industrial incinerator. The ballasts can be recycled after burning and c o o ling .

The polyurethane segments comprising ballast could be put into an industrial incinerator, to obtain the recycled ballast after being burned and cooled. The industrial incinerator could be selected from, but not limited to, pulse grate type incinerator, mechanical grate type incinerator, fluid bed incinerator, rotary incinerator or controlled air oxidation incinerator, preferably industrial incinerator integrated with function of automatic feeding, sieve, drying, incineration, cleaning, dust removing and controlling.

The water jet stream can be continuously ejected onto a surface of the polyurethane railway track bed to cut the polyurethane material comprised in the polyurethane railway track bed, and then eliminating or displacing the cut polyurethane railway track bed by water erosion, equipment excavation or other reasonable methods. The polyurethane railway track bed can also be cut layer by layer in several steps, for example, cutting the next layer after having cleaned up or displaced the segments of the preceding cut of the polyurethane railway track bed. Preferably, the cutting speed is 5-50 cm/min. During each cutting time, the cutting depth of the polyurethane railway track bed cut by the water jet stream (hereinafter referred as "cutting depth") i s 5-35cm. The polyurethane railway track bed not only includes a polyurethane railway track bed comprising ballasts and polyurethane material, but can also include a railway track bed wholly comprising polyurethane.

The excavator provided in the present invention, could be selected from wheel excavator or crawler excavator, preferably wheel excavator which could move on railway track, more preferably wheel excavator which could move both on railway track and ordinary road.

Preferably, it is possible to cut the polyurethane railway track bed while preventing the water jet stream from impacting a rail and/or a sleeper, by using the equipment provided in the present invention to eject the water onto a surface of the polyurethane railway track bed to cut the polyurethane material contained in the polyurethane railway track bed.

Hereinafter, the preferred embodiments of the method for cutting polyurethane railway track bed and the equipment for cutting polyurethane railway track bed will be further described by examples referring to the figures for better understanding. The description hereinafter is demonstrative but not restrictive.

Examples of preferred embodiments (illustrated by referring to the Figures): Example 1 : A polyurethane railway track bed 10, which would be cut, comprises polyurethane material 20 and ballasts 30 distributed in the polyurethane material 20. Sleepers 40 are set on the polyurethane railway track bed 10. Sleeper pad 50 is set between the polyurethane railway track bed 10 and the sleepers 40. Rail 70 is fixed on the sleepers 40 by using fasteners 60. The cross section of the sleeper along direction of the rail can be a square or rectangle (see Figure 1 A).

The equipment for cutting polyurethane railway track bed comprises a device for ejecting water, wherein the device for ejecting water comprises a nozzle 90, a high pressure water pipe 80 (see Figure IB), a pressure supplier and a water supplier (not shown). The equipment for cutting polyurethane railway track bed could comprise one or more devices for ejecting water. The devices for ejecting water are preferably arranged in one or more rows. The device for ejecting water could comprise a protecting device 100 (see Figure IB), the cross section of the protecting device 100 can be a square or a rectangle. The protecting device is used to prevent the water jet stream from impacting a rail and/or a sleeper.

When the nozzle 90 including the protecting device 100 is abut on the sleeper 40, the device for ejecting water can be started (the nozzle pressure is 30-150MPa, the diameter of the nozzle for ejecting the water is 0.1-1.0 mm, the distance from the nozzle to a surface of the polyurethane railway track bed is 1-12 cm, the cutting speed is 5-50 cm/min, the cutting thickness is 5-35 cm). When the nozzle 90 is moved along a surface of the sleeper 40 with the protecting device 100, the water is ejected along the direction of the surface of the sleeper onto a surface of the polyurethane railway track bed 10 to cut the polyurethane material in the polyurethane railway track bed 10 and prevent the water jet stream from impacting the rail 70 and/or the sleeper 40 (reference is made to Figures 1A and 1C).

After the cutting process for the polyurethane railway track bed 10 is finished, the excavator equipped with fork type grab hook or bucket can be used to take out the cut polyurethane railway track bed segments under the rail and sleeper, and transport the segments by train or truck thereafter.

In this example, it is good for the environment to use the water jet stream of pure water to cut polyurethane material in the polyurethane railway track bed, because no toxic substance or steam would be generated. In addition, due to the cooling properties of the water, no overheat effect would appear in the cutting area damaging the steel rail, fastener or mat in the cutting process; furthermore, the protector 100 could be used to prevent the water jet stream to damage the rail 70 and/ or the sleeper 40, as well as prevent the splashed polyurethane, water, ballasts to damage the nozzle 90 in the process for cutting the polyurethane railway track. Example 2:

The equipment in Fig. 2A further comprises a bend 1 10 connecting the nozzle and the high pressure water pipe compared to the equipment in Fig. IB.

When the nozzle 90 comprising the protecting device 100 is abut on the sleeper 40, the device for ejecting water can be started (the nozzle pressure is 250-600MPa, the diameter of the nozzle for ejecting the water is 0.1-1.0 mm, the distance from the nozzle to a surface of the polyurethane railway track bed is 1-12 cm, the cutting speed is 5-50 cm/min, the cutting thickness is 5-35 cm). When the nozzle 90 is moved along a surface of the sleeper 40 with the protecting device 100, the water is ejected along direction of a surface of the sleeper onto a surface of the polyurethane railway track bed 10 to cut the polyurethane material 20 and the ballasts 30 in the polyurethane railway track bed 10 and prevent the water jet stream from impacting the rail and/or the sleeper. Furthermore, the water could be ejected onto a surface of the polyurethane railway track bed 10, which is under the rail 70, due to the nozzle 90 which is connected with the high pressure water pipe 80 by the bend 110.

After the cutting process for the polyurethane railway track bed 10 is finished, the excavator equipped with fork type grab hook or bucket can be used to take out the cut polyurethane railway track bed segments under the rail and sleeper, and transport the segments by train or truck thereafter.

In this example, it is good for the environment to use the water jet stream of pure water to cut the polyurethane material and the ballasts in the polyurethane railway track bed, because no toxic substance or steam would be generated. In addition, due to the cooling properties of the water, no overheat effect would appear in the cutting area damaging the steel rail, fastener or mat in the cutting process; furthermore, the protector 100 could be used to prevent the water jet stream from damaging the rail 70 and/or sleeper 40, as well as to prevent the splashed polyurethane, water, ballasts from damaging the nozzle 90 in the process for cutting the polyurethane railway track. Example 3:

The polyurethane railway track bed 10, which would be cut, comprises polyurethane material 20 and ballasts 30 distributed in the polyurethane material 20. Sleepers 40 are set on the polyurethane railway track bed 10. Sleeper pad 50 is set between the polyurethane railway track bed 10 and the sleepers 40. Rail 70 is fixed on the sleepers 40 by using fasteners 60. The cross section of the sleeper along the direction of the rail is a trapezium (see Figure 3A).

The equipment for cutting polyurethane railway track bed comprises a device for ejecting water, wherein the device for ejecting water comprises a nozzle 90, a high pressure water pipe 80 (see Figure 3B), a pressure supplier and a water supplier (not shown). The equipment for cutting polyurethane railway track bed could comprise one or more devices for ejecting water. The devices for ejecting water are preferably arranged in one or more rows. The device for ejecting water could comprise a protecting device 100, the cross section of the protecting device 100 is a trapezium (see Figure 3B). The protecting device is used to prevent the water jet stream from impacting the rail and/ or the sleepers.

When the nozzle 90 comprising protecting device 100 is abut on the sleeper 40, thereafter the device for ejecting water is started (the water comprises abrasive material, the nozzle pressure is 10-30MPa, the diameter of the nozzle for ejecting the water is 0.4-1.0 mm, the distance from the nozzle to a surface of the polyurethane railway track bed is 5-50cm, the cutting speed is 5-50 cm/min, the cutting thickness is 5-35 cm). When the nozzle 90 is moved along a surface of the sleeper 40 with the protecting device 100, the water is ejected along direction of the surface of the sleeper onto a surface of the polyurethane railway track bed 10 to cut the polyurethane material in the polyurethane railway track bed 10 and prevent the water jet stream from impacting the rail 70 and/or the sleepers 40 (see Figure 3A and 3C.

After the cutting process for the polyurethane railway track bed 10 is finished, the excavator equipped with fork type grab hook or bucket can be used to take out the cut polyurethane railway track bed segments under the rail and sleeper, and transport the segments by train or truck thereafter.

In this example, it is good for the environment to use the water jet stream comprising abrasive material to cut polyurethane material in the polyurethane railway track bed, because no toxic substance or steam would be generated. In addition, due to the cooling properties of the water, no overheat effect would appear in the cutting area damaging the steel rail, fastener or mat in the cutting process. Furthermore, the protector 100 could be used to prevent the water jet stream from damaging the rail 70 and/or sleeper 40, as well as to prevent the splashed polyurethane, water, ballasts from damaging the nozzle 90 in the process for cutting the polyurethane railway track.

Example 4: The equipment in Fig. 4A further comprises a bend 110 connecting the nozzle and the high pressure water pipe compared to the equipment in Fig. 3B.

When the nozzle 90 comprising protecting device 100 is abut on the sleeper 40, thereafter the device for ejecting water is started (the nozzle pressure is 35-100MPa, the diameter of the nozzle for ejecting the water is 0.1-1.0 mm, the distance from the nozzle to a surface of the polyurethane railway track bed is 1-12 cm, the cutting speed is 5-50 cm/min, the cutting thickness is 5-35 cm). When the nozzle 90 is moved along a surface of the sleeper 40 with the protecting device 100, the water is ejected along the direction of a surface of the sleeper onto a surface of the polyurethane railway track bed 10 to cut the polyurethane material 20 and the ballasts 30 in the polyurethane railway track bed 10 preventing the water jet stream from impacting the rail and/or the sleepers.

Furthermore, the water jet stream could be ejected onto a surface of the polyurethane railway track bed 10, which is under the rail 70, due to the nozzle 90 which is connected with the high pressure water pipe 80 by the bend 110 (see Figure 4B).

After the cutting process for the polyurethane railway track bed 10 is finished, the excavator equipped with fork type grab hook or bucket can be used to take out the cut polyurethane railway track bed segments under the rail and sleeper, and transport the segments by train or truck thereafter.

In this example, it is good for the environment to use the water jet stream comprising abrasive material to cut polyurethane material and the ballasts in the polyurethane railway track bed, because no toxic substance or steam would be generated; in addition, due to the „

- 12 - cooling properties of the water, no overheat effect would appear in the cutting area damaging the steel rail, fastener or mat in the cutting process; furthermore, the protector 100 could be used to prevent the water jet stream from damaging the rail 70 and/or sleeper 40, as well as to prevent the splashed polyurethane, water, ballasts from damaging the nozzle 90 in the process for cutting the polyurethane railway track.

Although the present invention was illustrated through examples, it was not limited by these examples in any way. Without departing from the spirit and scope of this invention, those skilled in the art could make any modifications and alternatives. And the protection of this invention was based on the scope defined by the claims of this application.