Method for converting existing section track into continuous track

Abstract

FIELD: rail welding.SUBSTANCE: invention relates to aluminothermic welding of rails with simultaneous repair of defective sections of the rolling surface of the ends of the rails and can be used to convert an existing section track into a continuous track. The method involves loosening the ends of the rails, trimming them, and removing parts of the rail heads that comprise defects. A split mould is Placed around the ends of the rails and heat the ends of the rails and the split mould to a temperature of 1000-1500 °C, molten metal is fed from the reaction crucible into a split mould. Until the end of pouring, the temperature of the ends of the rails and the split mould is maintained at no less than 800 °C, the molten metal is held until it solidifies and forms a weld. The top portion of the welded rail is removed, the weld surfaces are ground, at least on the rail head, and the welded rail is secured. Molten metal is initially fed into the area of the rail soles. Next, molten metal is simultaneously fed into the area of the rail necks and into two vents, and molten metal is fed into the area above the rail heads, while maintaining the aforementioned reduction in feed into the two aforementioned vents.EFFECT: ensuring a defect-free connection of the ends of rails that had defects in the rolling surface area of the rail head.1 cl, 3 dwg

Description

[0001] Field of technology

[0002] The invention relates to aluminothermic rail welding, more specifically, to a method for converting an existing section track into a continuous track. The invention can be used for aluminothermic rail welding with simultaneous repair of defective areas of the rail end running surface in the joint area without removing the rails from the track.

[0003] State of the art

[0004] A form for aluminothermic welding of rails is known from the prior art, described in AT 13560 B, 10.10.1903, and providing for a lower smaller zone and an upper larger zone.

[0005] Also known from the prior art is a method for aluminothermic welding of rails, described in US 5531259 A, 02.07.1996, and providing that the form covers both the gap in the lower part of the ends of the rails and the increased gap in the upper part of the ends of the rails.

[0006] Also known in the prior art is a mold for aluminothermic welding of rails, described in RU 2559388 2, 10.08.2015, and providing that each of the half-molds is made expanded with the formation of an internal welding cavity in its middle and upper parts with a width not less than the length of the defective zone of the rolling surface of the rail head adjacent to the weld, with the possibility of surfacing the said zone with thermite metal simultaneously with welding the ends of the rails.

[0007] Furthermore, a method for converting an existing section track into a continuous track is known from the prior art, described in RU 2543112 C2, 27.02.2015, and providing for the creation of a permanent connection of the ends of the rails using aluminothermic welding by the method of intermediate casting in a butt gap, repair of defective sections of the rolling surface of the ends of the rails by the method of surfacing metal on them and subsequent mechanical processing of the weld seam and the ends of the rails adjacent to the weld seam to the geometric dimensions of the rail head.In this case, a gap is formed for pouring aluminothermic metal by cutting the ends of the rail with the removal of a portion of the defective sections of the rolling surface of the rail ends, after which the remaining portion of the defective sections of the rolling surface are ground, a casting mold for casting aluminothermic metal is installed in the butt gap, preliminary heating of the welded surfaces of the rail ends and the repair zone is carried out, and the surfacing of metal on the defective sections of the rolling surface of the rail ends is carried out by forming a riser above the heads of the rails and above the remaining portions of the defective sections of the rolling surface of the rail ends from aluminothermic metal poured from the bottom up into the butt gap and subsequent mechanical processing of the said riser to the geometric dimensions of the rail head.

[0008] The known method described in RU 2543112 C2 does not allow for defect-free connection of rails that have defects in the rail head rolling surface area, namely, depending on the metal pouring speed (determined by the cross-section of the casting mold channels), either underfills (welding defects) are formed in the rail head area (at a low pouring speed, ensuring the removal of gases and melted slags), or gas pores and slag inclusions are present in the rail head area (at a high pouring speed, ensuring the absence of underfills (welding defects) in the rail head area).

[0009] Disclosure of invention

[0010] Thus, the objective of the invention is to eliminate the disadvantages of the prior art, and the technical result of the invention is to create a method for converting an existing section track into a continuous track, which ensures a defect-free connection of the ends of rails that had defects in the rolling surface area of ​​the rail head, in particular, ensures the removal of gases and melted slags through the rail head area, as a consequence, the absence of gas pores and slag inclusions (throughout the entire cross-section of the rail, in particular, in the head area), and also ensures the absence of underfills (welding defects) in the rail head area.

[0011] The mentioned technical result is achieved through a method of converting an existing section track into a continuous track, which involves the following operations:

[0012] unfasten at least the ends of the rails,

[0013] They trim the ends of the rails and also remove parts of the rail heads containing defects, forming a gap of variable width,

[0014] install the ends of the rails to form a welding gap between their ends,

[0015] Place a split mold around the ends of the rails in the welding gap area and seal the contact of the split mold with the ends of the rails,

[0016] install a reaction crucible filled with a dose of aluminothermic composition over the mold,

[0017] Heat the ends of the rails and the split mold to a temperature in the range of 1000…1500°C,

[0018] ignite a dose of aluminothermic composition and heat it until molten metal is formed,

[0019] The molten metal is fed from the reaction crucible into the split mold,

[0020] The molten metal is initially fed into the rail base area,

[0021] Then simultaneously feed the molten metal into the rail neck area and into at least two vents,

[0022] then feed the molten metal into the rail head area, increasing the feed into this area by reducing the feed into at least two of the said vents,

[0023] then feed the molten metal into the area above the rail heads, while maintaining the said feed reduction into at least two of the said vents,

[0024] until the end of pouring is completed, the temperature of the rail ends and the split mold is maintained at no less than 800°C,

[0025] withstand molten metal until it solidifies and forms a weld,

[0026] remove the profitable part from the head of the welded rail,

[0027] Grind the weld surfaces at least on the rail head,

[0028] Fix the welded rail.

[0029] It should be noted that the described design allows for a defect-free connection of the ends of rails that had defects in the rolling surface area of ​​the rail head, in particular, due to a more uniform rise in the metal level vertically, ensures the removal of gases and melted slags through the rail head area, as a result, the absence of gas pores and slag inclusions (throughout the entire cross-section of the rail, in particular, in the head area), and also ensures the absence of underfills (welding defects) in the rail head area.

[0030] Brief description of the drawings

[0031] The invention is explained by the following graphic materials.

[0032] Fig. 1. Casting mold for aluminothermic welding of rails, cross-section along the axis of the side channel and the axis of the thrust (schematic).

[0033] Fig. 2. Casting mold for aluminothermic welding of rails, longitudinal section along the thrust axis (schematic).

[0034] Fig. 3. Casting mold for aluminothermic welding of rails, longitudinal section along the axis of the side channel (schematic).

[0035] Implementation of the invention

[0036] The method for converting an existing jointed track into a continuous track is implemented as follows.

[0037] At least the ends of the rails are loosened. At a minimum, the fixing plates are removed and the fasteners are unscrewed, loosening the rail end from at least three or four nearby sleepers. In some cases, the entire rail is loosened, for example when it needs to be moved or when replacing a rail.

[0038] Rail ends are trimmed, for example, with a blade or abrasive tool, or less commonly, a gas cutter. The same tools are used to remove defective parts of the rail heads, creating a gap of variable width. A typical defect is spalling on the rail head rolling surface and / or its fillet, with a depth of more than 3 mm and a length of more than 25 mm.

[0039] The rail ends are installed, creating a welding gap between their ends. A reasonable gap for aluminothermic welding with intermediate casting is 25±2 mm (the gap is determined between the ends of the rail bases and / or webs). However, the described aluminothermic welding method can also be used with a gap of 50 mm or more.

[0040] In turn, the gap in the area of ​​the rail heads is determined by the dimensions of the removed parts of the rail heads that contained defects, and, as a rule, increases by 30...40 mm in each direction (relative to the gap between the ends of the soles and / or webs of the rails).

[0041] Next, a split mold is placed around the rail ends in the welding gap area and the contact between the split mold and the rail ends is sealed. The contact area between the mold and the rail is sealed with molding material, which can be, for example, a material based on kaolin and asbestos wool, although the use of other molding materials is not excluded.

[0042] A reaction crucible filled with a dose of aluminothermic composition is installed above the mold, for example on a rotating bracket.

[0043] Heat the rail ends and the split mold to a temperature in the range of 1000–1500°C. A gas torch with a properly adjusted flame is moved to the welding zone for this heating. Within 7–12 minutes, the rail ends and the casting mold are heated to a temperature of 1000–1500°C. It should be noted that heating above 1500°C is impractical, as it may cause partial melting of the rail metal. However, heating below 1000°C does not prevent rapid cooling (during pouring) of the molten metal being poured into the split mold, thereby ensuring the release of slag and gases.

[0044] The aluminothermite mixture is ignited (a lit thermite match is inserted into the center of the aluminothermite mixture) and heated until molten metal forms. The molten metal is then transferred from the reaction crucible to a split mold. After ignition of the aluminothermite mixture, alloying, refining, and deoxidizing reactions occur, resulting in its heating until molten weld metal forms. After 20-28 seconds, the molten weld metal is automatically released from the crucible into the split mold, where it fills the weld gap from the bottom up.

[0045] To implement the method of converting an existing section track into a continuous track, the casting mold for aluminothermic welding of rails illustrated in the figures can be used.

[0046] The molten metal is initially fed (see pos. 1 - side channels) into the area of ​​the rail soles (2).

[0047] Then simultaneously feed molten metal into the neck area (3) of the rails and into at least two vents (4).

[0048] Next, molten metal is fed (see pos. 5 - middle channels) into the area of ​​the rail heads (6), increasing the feed into this area by decreasing (see pos. 7 - narrowing the cross-section of the riser) the feed into at least two of the mentioned risers (4).

[0049] Accordingly, a more uniform pouring speed can be achieved across the entire height of the rails.

[0050] Next, molten metal is fed (see pos. 8 - upper channels) into the zone (9) above the rail heads, while maintaining the aforementioned reduction in feed into at least two of the aforementioned risers (4). In particular, when the rising portion is formed, the casting bridge is extruded.

[0051] Until the end of pouring (especially during the final stage of pouring), maintain the temperature of the rail ends and the split mold at no less than 800°C to prevent rapid cooling (during pouring) of the molten metal being poured into the split mold, thereby ensuring the release of slag and gases. For this purpose, provide additional external heating of the mold and rail ends, for example, with burners, and provide protection from atmospheric precipitation (if present).

[0052] After the mold is completely filled, the molten metal is held until it solidifies and a weld is formed (about 4...5 minutes).

[0053] Next, the riser is removed from the welded rail head using a trimming device, and the remaining weld is cleaned of any remaining mold material. The weld surface on the rail head is then ground to a height of 1–1.5 mm above the top of the rail head. After the weld has completely cooled (to ambient temperature in approximately 15–20 minutes), the entire weld on the rail head is ground to the rail head size with a tolerance of 0.3 mm.

[0054] After the rail section has completely cooled and been cleaned, it is secured. Ultrasonic non-destructive testing is then performed.

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