RU2543112C2 - Method to rearrange existing jointed rail track into continuous welded rail track - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method includes creation of non-detachable connection of rail ends using aluminothermic welding by the method of intermediate casting into a joint gap, repair of defective areas of rolling surface of rail ends by method of welding of metal onto them and subsequent mechanical treatment of the welded joint and rail ends adjacent to the welded joint, to geometrical dimensions of the rail head. A gap is formed for casting of aluminothermic metal by cutting of rail ends with removal of some defective sections of rolling surface of rail ends. The remaining defective areas of rolling surface are polished, a casting mould is installed to cast aluminothermic metal into a joint gap, welded surfaces of rail ends and repaired area are previously heated. Metal is welded onto defective areas of rolling surface of rail ends by formation of a top part above rail heads and above remaining parts of defective areas of rolling surface of rail ends from aluminothermic material cast bottom up into the joint gap and subsequent mechanical treatment of the specified top part to geometrical dimensions of the rail head.

EFFECT: improved quality of a welded joint, time and labour cost savings, reduced number of used equipment and resources for performance of works.

5 cl, 7 dwg

Description

The invention relates to the reconstruction of the current link rail track in a weld-free path with the simultaneous repair of defective sections of the rolling surface in the joint zone using aluminothermic welding in place without removing them from the canvas.

When reconstructing the existing link rail track into a jointless path, as a rule, it becomes necessary to repair worn and defective rail ends. The closest analogue of the invention is a method of converting an existing joint rail track into a weld-free path, according to which the ends of the rails are joined in the joint zone by aluminothermic welding with intermediate casting between the ends of the rails. After aluminothermic welding, without waiting for the final cooling of the welded ends of the rails, the aluminothermic metal is deposited onto the upper surface of the rails in the area adjacent to the weld. The final abrasive treatment of the weld is carried out together with the abrasive treatment of the deposited aluminothermic metal (see patent RU 2378440, E01B 11/52, B23K 23/00, published on January 10, 2010, selected as a prototype).

However, this method provides for the use of two types of heterogeneous technological equipment - for, in fact, aluminothermic welding and equipment for performing electric arc surfacing, which significantly complicates and increases the cost of converting the link rail track into a welded jointless path. The operating time on the existing track is increased due to the sequential use of two technological processes, which is also a drawback, since it requires an increase in the duration of the process and, thereby, an increase in the closing time of the stages to perform work.

In this method, the weldability of three metals that differ in their chemical composition (rail steel, aluminothermic metal, surfacing wire) must be ensured, which reduces the quality of the welded joint due to the possible formation of cracks.

Performing surfacing after removing profits and the mold creates the conditions for contamination of the surfacing surface with residues of the mold material, which also reduces the quality of the welded joint, because may lead to the formation of defects in the deposited metal and its detachment from the rail metal.

The objective of the present invention is to improve the quality of the welded joint and simplify the process of converting the link rail track in a continuous joint on the existing track in the field.

The technical result consists in combining the surfacing of aluminothermic metal with pouring in the butt gap of aluminothermic metal and the formation of aluminothermic metal from the part of the last surfacing, as well as preventing the possibility of contamination of the welded surfaces with the remains of the casting material and providing conditions for the formation of overlays identical to the conditions of welding of the ends rail in the welding gap between the ends of the rail.

The indicated task and technical result are achieved due to the development of a method for converting the existing link rail track to a welded jointless path with the repair of defective sections of the rolling surface in the joint zone, which provides for the creation of an integral connection of the ends of the rails using aluminothermic welding by the method of intermediate casting into the butt gap, repair of defective sections of the rolling surface the ends of rails by the method of surfacing on them aluminothermic metal used in casting, and the subsequent mechanics kuyu processing and weld the ends of the rail adjacent to the weld. to the geometric dimensions of the rail head. To do this, form a gap for pouring aluminothermic metal by cutting the ends of the rail to remove part of the defective sections of the rolling surface of the ends of the rails, after which the remaining part of the defective sections of the rolling surface is ground, a casting mold for casting aluminothermic metal into the butt gap is installed, and the welded surfaces of the rail ends are preheated. and repair zones, and the deposition of aluminothermic metal on defective sections of the rolling surface of the rail ends is carried out by Bani profitable part of the heads of the rails and on the remaining portions of defective portions rolling surface of the rail ends of the filling from the bottom up in the seam gap aluminothermic metal and subsequent machining of said part to the geometrical profitable rail head sizes.

The indicated task and the technical result are also achieved by the fact that for the formation of a profitable part above the rail heads forming the specified surfacing, use part of the last portions of aluminothermic metal supplied at the end of casting to the butt gap in the zone of the rail head and above it.

As well as those. that the machining of the profitable part forming the specified surfacing and the machining of the weld and the ends of the rails adjacent to the weld are performed simultaneously at a metal temperature of 1000-1100 ° C with a metal layer remaining over the rail heads for subsequent precision machining.

And also the fact that the thickness of the metal layer for subsequent precision machining is not more than 4 mm.

And also the fact that the specified precision machining of the remaining layer of the profitable part forming the specified surfacing is performed at ambient temperature.

In the patented method, not only the welding of the ends of the rails is carried out by welding, but also the simultaneous repair of the worn ends of the rails. The patented method allows you to perform these operations within the framework of one technological process with ensuring weldability of two metals. At the same time, the quality of the welded joint is improved, time and labor costs are saved, and the amount of equipment and resources used for work is reduced.

Figure 1 shows the worn ends of the rails of the link path in the joint zone.

Figure 2 shows the formation of the butt gap for welding and repair areas of the ends of the rails by surfacing.

Figure 3 shows the installation of the mold for welding and surfacing, as well as a disposable reaction crucible loaded with aluminothermic mixture.

Figure 4 shows a split mold for welding and surfacing (cross section).

Figure 5 shows a cross-section of a mold in a detachable form along line AA of Figure 1 with a view of the channels for supplying molten aluminothermic metal to the welding and surfacing zones.

Figure 6 shows the ends of the rails after welding and surfacing.

7 shows the welded and repaired ends of the rails after the final machining of the rail head in the welding and surfacing zone.

The method is as follows.

The size of the joint gaps in the rails of the link path can vary from 0 (zero clearance for merged rails) to 22-24 mm, depending on the length of the rails 12.5 m or 25 m and the diameter of the holes for bolt-on linings - 36 mm or 40 mm.

Signs of defective rails of the link path are chipping on the tread surface of the head or on its fillet with a depth of more than 3 mm with a length of more than 25 mm - in the main tracks with a load intensity of more than 25 million tkm gross / km per year and chipping with a depth of more than 4 mm for a length of more than 35 mm - in the main tracks with a cargo intensity of less than 25 million ton-km of gross km / km per year and pick-up and drop-off tracks.

In the case of the reconstruction of the link path with merged rails when forming a gap for aluminothermic welding with a width of 24 mm by cutting 12 mm from the connected ends of the rails, the length of the defective section of the rolling surface to be welded will be reduced by the same amount. It will be 13-23 mm, depending on the depth of spalling and weight-bearing.

With a maximum butt gap of 24 mm, the length of the cladding to eliminate the defect will be 25-35 mm.

To obtain high-quality surfacing, surfaces with defects must first be ground at ambient temperature in order to eliminate dents from chipping and microcracks. For pouring into the gap and into the repair zone, the mold has an extension in the upper part, which covers the ends of the rails in the area of the rail head.

The expansion of the mold in the area of the rail head to ensure surfacing of the adjacent rolling surface is determined by the length of the deposited surface. In order to achieve uniform flow of molten aluminothermic metal into the weld zone, the mold is provided with additional channels. The cross-sectional shape of the channels can be different.

Patented method is as follows.

The implementation of the claimed method of converting the existing joint rail track into jointless one begins with the disassembly and removal of the overhead bolt joint of the ends of the rails forming the joint.

Disassembly of the overhead bolt connection of the rails is carried out using wrenches using a drive for machining the weld.

Figure 1 shows the worn ends of the rails 1 and the existing gap S in the joint area with the overhead bolt connection 2. Positions 3 and 4 denote sleepers and crushed stone, respectively.

The size of the joint gap of the link path can be in the range from 0 to 22-24 mm.

Positions I and II indicate worn sections of the ends of the rails. The nature of the defects in the rolling surface of the ends of the rails to be eliminated during the repair process is evaluated, and the gap between their ends for welding and surfacing is determined by the intermediate casting method.

The width of the gap depends on the extent of the defects from the ends of the rails and the existing gap S in the joint zone. After this, they begin to form a zone of welding and repair of the ends of the rails by surfacing with aluminothermic metal.

Figure 2 shows the formation of the gap for welding t and the length of the repair zone of the ends of the rails r1 and r2.

The weld gap t for aluminothermic welding can be 24 mm, 50 mm or 75 mm, depending on the accepted length of the repair zone of the ends of rails r1 and r2, which can reach a value of 35 mm.

The formation of a gap for welding is carried out using a mechanized, including abrasive, or manual, such as a hacksaw for metal, metal cutting tool.

The repair area for surfacing the surface with aluminothermic metal is ground to remove defects in the form of dents with chipping and microcracks.

On the formed gap for welding and surfacing set the mold, pre-heat the ends of the rails and set the crucible with aluminothermite.

Figure 3 shows the reaction crucible with aluminothermite 5 mounted on the mold 6. Mounting the mold on the rails is not shown. After the installation of the mold, the ends of the welded rails and the weld zone are preheated to a temperature of 900-1000 ° C using a gas burner (not shown in the drawing) to improve weldability and reduce the consumption of aluminothermic mixture.

To equalize the temperature field of heating the ends of the welded rails and the zone of aluminothermic surfacing in order to ensure high-quality heating, it is necessary to install a gas burner nozzle at a height of 45-50 mm above the level of the mold.

After preheating, a reaction crucible with aluminothermite is mounted on the mold to produce aluminothermic metal. The reaction crucible can be disposable and can be mounted directly on the mold, as shown in FIG. 3 or reusable with mounting on an arm above the mold (not shown).

After ignition of the aluminothermic mixture, which is ignited with a special match, after 25-30 seconds, the aluminothermic steel is smelted, which fills the mold 6 within 4-5 seconds.

Figure 4 shows a detachable mold for welding and surfacing (cross section), and figure 5 shows a cross section of a mold for detachable along line AA of Figure 1 with a view of the channels for supplying and discharging excess molten aluminothermic metal to the welding zones and surfacing.

The mold is detachable, it consists of the left half mold 7, the casting bridge 8, the right half mold 9, the collection chamber of the aluminothermic metal 10, the lowering channels 11 for pouring the aluminothermic metal into the inner volume of the mold, channels 12 for removing excess molten aluminothermic metal from the zone 13 of the rail head casting and surfacing, as well as additional channels 14. The molten aluminothermic metal from the collection chamber 10 is divided into two streams by a casting bridge 8. The molten aluminothermic metal through the lowering channel 11 pouring aluminothermic metal enters the zone 16 of the filling of the bottom of the rail, then upstream fills the zone 15 of the filling of the neck of the rail. Fresh portions of aluminothermic metal enter through additional channels 14 into the zone 13 of the filling of the rail head and repair by surfacing of the rolling surface. The cross-section of the additional channels may be different in shape. Excess aluminothermic metal exits through channels 12, which can also be of various shapes. The direction of flow of the poured aluminothermic metal in the mold is shown by arrows.

In the process of intermediate casting of aluminothermic metal with a flow direction to zone 16 of the rail sole, the separation of aluminothermic metal and slag is completed. With further upward movement of the flow of molten aluminothermic metal between the ends of the rail, the slag and bubbles from the exhaust gases are on top and are removed primarily through the channels 12 outside the mold. Excess aluminothermic metal forms a profitable part above the rolling surface of the rail.

Figure 3 shows a cross-section of a castable mold in the area of the channels for supplying molten aluminothermic metal to the welding and surfacing zones. The drawing shows that the mold in the repair of the ends of the rails by surfacing with aluminothermic metal expands. The molten aluminothermic metal through the channels 14 is supplied to complete the formation of a welded joint of the rails and eliminate defects of the rolling surface.

Such a phased filling of the three zones of the mold 16, 15 and 13 starting from the bottom zone 16 with the upward flow of molten aluminothermic metal does not allow the aluminothermic metal and rail ends to cool below the optimum temperature to ensure weldability, which should not be lower than 900 ° C.

The proposed motion scheme of molten aluminothermic metal inside the casting mold promotes good washing of the ends of the rails in the gap for welding t and the zone of repair of the rolling surface r1 and r2, ensures their good penetration, weldability and surfacing. In addition, the accumulating gas under the casting bridge 8 increases the pressure in the upper zone 13 of the filling of the rail head and surfacing. This helps to prevent the boiling of molten aluminothermic metal above the head of the rail ends and in the surfacing zone, which improves the structure of aluminothermic metal and improves the quality of surfacing and weld.

After pouring the molten aluminothermic metal into the mold, its temperature begins to decrease and the crystallization process begins, which lasts 4.5-5 minutes.

After partial hardening of the aluminothermic metal of the weld with the weld zone to a temperature of about 1000-1100 ° C, its profitable part above the rolling surface of the rail head is removed with a trimmer (not shown).

Thus, metal surfacing on the defective sections of the rolling surface of the rail ends is carried out by forming a profitable part above the rail heads and over the remaining parts of the defective sections of the rolling surface of the rail ends from the aluminothermic metal poured into the butt gap and subsequent machining of the specified profitable section to the geometric dimensions of the rail head.

Figure 6 shows the welded and weld ends of the rails after removing the profitable part. The profitable part is cut so that over the weld 18 and the weld metal in the repair zone there is a layer up to 4 mm high for preliminary hot grinding.

Hot grinding of the deposited zone and the weld is performed together at a surface temperature of rails of 600-800 ° C to a height of about 1 mm above the rolling surface. After the welded joint and repair surfacing are completely cooled to ambient temperature, they complete its final abrasive treatment by grinding to a level of the rolling surface of the rail, which has not been surfaced.

Figure 7 shows the welded and repaired ends of the rails after the final machining of the rail head in the welding and surfacing zone. The linear dimensions of the ends of rails connected and repaired by surfacing on the rolling surface after welding and surfacing are checked using a meter-long metal ruler 19. Saddles (downward deflections) in welded joints and weld ends are not allowed. The elevation of the weld in the vertical plane depends on the speed of trains and is 0.2-0.8 mm at speeds from 160 to 40 km / h, respectively.

The results of the experimental work on the conversion of the existing link rail track to a weld-free track by welding with simultaneous repair of the skating surface in the joint zone using intermediate casting of aluminothermic metal showed that durable welded joints of rails with high-quality skating surface geometry are obtained, reliability and operational characteristics of the railway track are increased.

Claims (5)

1. A method of converting the existing link rail track to a weld-free track, including the creation of an integral connection of the rail ends using aluminothermic welding by the intermediate casting method in the butt gap, repair of defective sections of the rolling surface of the rail ends by welding metal onto them and the subsequent mechanical processing of the weld and rail ends adjacent to the weld, to the geometric dimensions of the rail head, characterized in that they form a gap for pouring aluminothermic metal put m trimming the ends of the rail with the removal of part of the defective sections of the surface of the rolling ends of the rails, after which the remaining part of the defective sections of the surface of the grinding is ground, set the mold for casting aluminothermic metal in the butt gap, pre-heat the welded surfaces of the ends of the rails and the repair zone, and the metal is deposited onto defective sections of the rolling surface of the ends of the rails are carried out by forming a profitable part above the rail heads and over the remaining parts of the defective sections the surface of the rolling of the ends of the rails from the bottom-up cast into the butt gap of the aluminothermic metal and subsequent machining of the specified profitable part to the geometric dimensions of the rail head. 2. The method according to claim 1, characterized in that for the formation of a profitable part above the rail heads forming the specified surfacing, use part of the last portions of aluminothermic metal supplied at the end of casting to the butt gap in the area of the rail head and above it. 3. The method according to claim 1, characterized in that the machining of the profitable part forming the specified surfacing, and the machining of the weld and the ends of the rails adjacent to the weld, are performed simultaneously at a metal temperature of 1000-1100 ° C with leaving above the rail heads metal layer for subsequent precision machining. 4. The method according to claim 3, characterized in that the thickness of the metal layer for subsequent precision machining is not more than 4 mm 5. The method according to claim 1, characterized in that the specified precision machining of the remaining layer of the profitable part forming the specified surfacing, is performed at ambient temperature.

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