RU2124424C1 - Rail repair method - Google Patents

Abstract

FIELD: railway transport; maintenance and repair of rails without removing from bed. SUBSTANCE: defective section of rail is cut out and ends of rails are released at both sides. Then rails are lifted by 1.0-1.5 mm and fixed in this position. Rails are welded by aluminothermic fusion welding method. If length of defective section exceeds 70 mm, at least 3 m of rail is cut out and sound section of rail is installed in its place. Then aluminothermic fusion welding of butt ends is carried out. EFFECT: reduced time taken for repair, enhanced quality of repaired rail section. 5 cl, 1 dwg

Description

 The invention relates to methods for repairing rails of a railway track in place, without removing them from the canvas.

 There is a known method of repairing rails, in which the rails of standard length (12.5 m or 25 m) with a defect detected in them are disconnected at the docking nodes and completely removed. Instead of a defective rail, a new standard-length rail is installed.

 The disadvantage of this repair method is the high consumption of metal.

 The closest known method of repairing rails of a jointless railway line, in which a defective rail section is removed and a similar length-free section is welded in without defects (see description to SU, copyright certificate N 998061, class B 23 P 6/04 // B 23 K 101: 26, 02.23.83).

 The disadvantage of this method is the low quality of the weld, the use of energy-intensive welding methods for connecting rails.

 The objective of the invention is to obtain equal strength with the main rail of the restored area, improving the quality of the welded joint through the use of aluminothermic welding with intermediate casting while reducing repair time.

 This problem is achieved by the fact that in the method of repairing rails, including cutting out a defective portion of the current path and connecting the ends of the rail by welding, in contrast to the prototype method, before connecting the ends of the rail, they are relaxed on the current path in both directions, lifted and fixed in this position, and the connection of the ends of the rail is carried out by aluminothermic welding with intermediate casting between the ends of the rail. The ends of the rails are relaxed by 1 - 2 m, raised by 1.0 - 1.5 mm and the ends of the rail are welded, the distance between which does not exceed 70 mm. When the length of the defective section is more than 70 mm, a rail section of at least 3 m in length is cut out, a piece of the defect-free rail is installed in its place and aluminothermic welding of the joints is carried out.

 The drawing shows a device for repairing rails using aluminothermic welding with intermediate casting.

 The claimed method is as follows.

 A section of a rail with a detected defect (for example, defects 21-1 and 21-2 in accordance with the catalog of rail defects NTD / CP-2-93), up to 10 mm long, is cut out, for example, by an autogen. The size of the removed piece of rail exceeds the size of the defect, i.e. captures undisturbed sections of the rail on both sides. To eliminate the deflection of the rail at the weld place after removing the defective piece, the ends of the rail are relaxed by 1–2 m on both sides. Then they are lifted by 1.0–1.5 mm and fixed in this position. The distance between the ends of the rail can reach 70 mm. The optimum gap for aluminothermic welding with intermediate casting is 24 - 26 mm. The ends of the rail are pre-cleaned of rust, scale, paint and grease using a metal brush and abrasive materials or by burning with an oxygen acetyl flame with excess oxygen. After that, the ends of the rail are connected by aluminothermic welding with intermediate casting.

 To do this, in the place of the weld gap is placed a split mold 1, consisting of two half-forms. To do this, two half-molds are inserted in the holder 2 in the form of metal frames 3. First, on one half-mold, the casting trough is filled with mastic, and on the other, the weakened wall of the casting trough is removed to remove slag and the ladle is attached to collect slag.

 To the contact point of the rails on the head 4 of the end of the rail 5, a combined stand 6 is attached so that the holders 7 of the half-forms and the half-forms themselves are directed along the axis of the weld gap.

 A gas burner with a fine-tuning mechanism (not shown) is fixed to the combined rack 6, with which the burner is installed exactly along the axis of the weld gap. The burner prepared for operation is removed to the side from the weld gap to an auxiliary stand (not shown).

 The contact point of the mold with the rail is sealed with molding material, for example, material based on kaolin and asbestos wool can be used.

 The reaction crucible 7 is filled with a dose of aluminothermic composition, installed over the detachable form 1 on the bracket 8 of the combined rack 6 and rotated 90 degrees to the side of the weld gap.

On the gas reducers of the gas burner, a propane pressure of 3.5 Bar, an oxygen pressure of 1 Bar is set, after which the burner is ignited and re-installed on the auxiliary rack. A torch with a normally adjusted flame is moved to the welding zone to preheat the ends of the rails 5 and the injection bridge of form 1 and the form 1. The heating time, for example, for the R-65 rail is 7-10 minutes. During this time, the ends of the rails are heated to a temperature of 800 - 1500 ^o C. As shown by experiments, such a temperature is necessary to obtain a high-quality weld that has the necessary strength of the connection of the ends of the rails forming a single monolithic welded rail, both in summer and in winter. One minute before the end of heating of the ends of the rails 5 and form 1, the injection bridge of form 1 is heated, after which a termite match (not shown) is ignited from the burner flame.

 A lit match is inserted into a dose of aluminothermic composition and the crucible 7 is covered with a lid. After ignition of a dose of aluminothermic composition 14, alloying, refining and deoxidizing reactions occur, as a result of which it is heated to the formation of molten welded metal and after 20 to 28 seconds the molten welded metal is automatically released from crucible 7 into a split mold 1 in which it is bottom-up fills the weld gap.

 When the physical state of the molten welded metal filling the weld gap changes, gases are released and slags are smelted (removed) from it.

 Gases and slags float from the molten welded metal filling the weld gap and pass into the profitable (weld) part of the weld formed above the heads of the ends of the rails 5, i.e. outside the weld gap. T.O. in the profitable part of the weld above the heads of the ends of the rails, contaminants and bubbles from the exhaust gases are concentrated, and the weld metal remains without any defects, i.e. there are no inclusions of slags and gas bubbles in it.

 The crystallization time of the weld metal, depending on the dose of the aluminothermic composition, lasts 4.5 - 5 minutes.

 After the weld metal has solidified, its profitable part is removed from the head of the welded rail with a trimmer (not shown), and then the surface of the weld on the rail head is ground to a height of about 1 mm above the top of the rail head, and after the weld has completely cooled down (to ambient temperature ) grind the entire weld on the rail head to the size of the rail head with a tolerance of 0.3 mm.

 After stripping the weld from the rail head, the rest of the weld from the mold material is cleaned.

 Raising the ends of the rails by 1.0 - 1.5 mm and welding them in this position ensures a smooth (without dips) on the rail head during aluminothermic welding of the ends of the rails.

 It turns out a high-quality welded joint of rails, which is confirmed by the results of experimental weldings. Welding of rails on railways showed that we obtain strong and durable welded joints of rails that can withstand significantly greater loads and for a longer period of operation.

 In the case of extended defects (more than 70 mm), if necessary, replace the rail section with a new, defect-free, aluminothermic welding of two joints is performed according to the technology described above.

 Thus, the proposed repair method can be used when restoring rails with defects of various lengths and with any characteristics.

Claims (5)

 1. A method of repairing rails, including cutting out a defective portion of the current path and connecting the ends of the rail by welding, characterized in that before connecting the ends of the rail they are relaxed on the active path in both directions, lifted and fixed in this position, and the connection of the ends of the rail is carried out by aluminothermic welding with intermediate casting between the ends of the rail.  2. The method according to claim 1, characterized in that the ends of the rails are raised by 1.0 - 1.5 mm  3. The method according to claim 1 or 2, characterized in that the ends of the rail are welded, the distance between which does not exceed 70 mm.  4. The method according to claims 1, 2 or 3, characterized in that the relaxation of the ends of the rails is carried out at 1 - 2 m  5. The method according to claim 1 or 2, characterized in that when the length of the defective section is more than 70 mm, a rail section of at least 3 m is cut out, a piece of defect-free rail is installed in its place and the joints obtained are welded.