RU2632750C2 - Method of manufacturing bimetallical steel and aluminium contact rails - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: plurality of rail bearing profiles of aluminium or an alloy thereof is manufactured with corresponding face surfaces of their heads. The profiles are laid parallel to each other on a horizontal platform with their faces oriented upwards, so that there is a gap between the heads of any two adjacent rail bearing profiles of said plurality. After that, a single steel sheet is installed over the faces of the plurality of the rail bearing profiles laid in this way, with an offset from these surfaces. An explosive is applied to this sheet on top over its entire area, and the explosive initiation is carried out, which determines the process of welding by blasting of steel contact pads against the faces of the heads of the rail bearing profiles.

EFFECT: simplifiying the manufacture technology of contact rails due to the simultaneous formation of a plurality of bimetallic rails by means of welding a single steel sheet to the plurality of the bearing profiles and cutting this steel sheet into parts along the perimeters of the heads of these profiles.

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Description

FIELD OF THE INVENTION

The present invention relates to methods for rolling profile metal, as well as to methods for manufacturing contact bimetallic rails using explosion welding and can be used in the manufacture of current-carrying rails for the subway.

State of the art

A known method of manufacturing a bimetallic steel-aluminum contact rail, which includes the manufacture of an I-beam with a bimetallic head by hot pressing a full profile of an I-beam from aluminum or its alloys with the simultaneous supply of stainless steel tape. During pressing in a matrix of a special design, a metal bond forms between the base metal and the overlay (Dr. sc. Nat. JJ THELER, Ing. (Grad.) A. WAGNER und Ing. (Grad.) A. AMES, Singen. Herstellung von Aluminum / Stahl - Verbundstromschienen mit metallurgischer Bindung zwischen Aluminum und Stal durch Verbundstrangpressen. Mitteilung der Aluminum - Walzwerke Singen. Metallwissenschaft und Technik. MET. 30, Jahrgang. Marz 1976. Heft 3).

The features of the known method, which coincide with the features of the claimed invention, consist in hot pressing a full profile of an I-beam from aluminum or its alloys, in attaching a steel contact plate to the I-shelf by diffusion.

The reason that prevents the obtaining in the known method of a technical result, which is provided by the invention, is that the above-mentioned joining of a steel contact strip is carried out in the process of said hot pressing by simultaneously supplying a stainless steel tape. As a result of this, a current lead is formed with an unreliable metal connection between the base metal (aluminum) and the steel plate, the occurrence of burns due to unreliable contact with the current collector of the train and, as a result, a short service life. In addition, the known method requires complex construction and commissioning of equipment for the manufacture of current lead, which entails an increase in its cost.

The closest analogue (prototype) is a method of manufacturing a bimetallic steel-aluminum contact rail, which consists in the fact that first a T-section profile is made by pressing, then by joint rolling of a billet from aluminum or its alloys and a steel strip, a bimetallic head with a convex outer surface is made, then by welding of the bimetallic head (its aluminum part) and the T-section profile obtain an I-rail profile (patent RU No. 2217248 C1, IPC B21B 1/08, B23 31/02, V23K 101: 26, published 27.11.2003).

The reason that prevents the obtaining in the known method of a technical result, which is provided by the invention, is that the T-section profile is separately made from aluminum or its alloy, the bimetallic steel-aluminum head is separately manufactured by joint rolling of two metals (aluminum and steel), after which welding is carried out the specified head with the specified profile of the T-section. Separate manufacture of a bimetallic head and its subsequent welding on aluminum to the T-profile complicates the technology of manufacturing a contact rail and reduces its operational reliability, since the aluminum bearing profile of the rail is not solid and the mechanical connection of the steel strip with aluminum is not ensured.

Disclosure of invention

The problem to which the invention is directed, is to increase the operational reliability of rails, to simplify the manufacturing technology of contact rails, reduce the time it takes to complete operations, and increase labor productivity.

The technical result that mediates the solution of this problem consists in the monolithic execution of a rail bearing profile made of aluminum or its alloy and in increasing the strength of the connection of the steel contact plate with this bearing profile (at least 100 MPa, which significantly increases the operational reliability of the rail); as well as in the simultaneous and automatic execution of the welding operation by explosion welding of a single steel sheet simultaneously to a plurality of rail bearing profiles and cutting this steel sheet into parts along the perimeters of the heads of these profiles (which simplifies the technology, reduces time, increases productivity).

The technical result is achieved in that in the method for manufacturing bimetallic steel-aluminum contact rails, each of which contains a rail bearing profile made of aluminum or its alloy and including a head for placing a steel contact plate on it, as well as a steel contact plate connected to the head, prefabricated rail bearing profiles are laid parallel to each other on a horizontal platform with the front surfaces of their heads up with a gap between the heads of adjacent rail bearing profiles and with the placement between the walls of adjacent rail bearing profiles of the tabs, the height of which is chosen from the conditions of support for these heads, while the said tabs are made of material harder than the material of the rail bearing profile, and then placed with a gap relative to the face of the laid rail bearing profiles a single steel sheet that overlaps all these front surfaces, then explosives are poured over the entire area of the steel sheet, o initiation and welding of a steel sheet by explosion to the heads of rail bearing profiles with the formation of steel contact plates on these heads.

Brief Description of the Drawings

The accompanying drawings show, by way of example, an assembly (package) of two I-beam rail supporting profiles made of an aluminum alloy prepared for welding steel contact plates to the faces of their heads by an explosion.

The implementation of the invention

The technological cycle for the production of bimetallic steel-aluminum contact rails includes three successive stages.

At the first stage, a lot of rail bearing profiles are made of aluminum or its alloy with the corresponding front surfaces of their heads for subsequent installation by diffusion on these surfaces of steel contact plates. The manufacture of each bearing profile is carried out by hot extrusion from aluminum billets (wrought aluminum alloys). For pressing, aluminum deformable alloys of the 1XXX series (technical and electrical aluminum), 2XXX (group Al - Cu - Mg - Mn), 3XXX (group Al - Mn), 5XXX (group Al - Mg), 6XXX (group Al - Mg - Si), low- and medium-alloyed alloys of the 7XXX series (Al - Zn - Mg group). Before pressing the workpiece, it is preheated to a temperature that ensures the optimal ductility of the aluminum alloy during its deformation in order to reduce the load on the pressing tool. The heating temperature of the preform before pressing can vary depending on the alloy grade and technical requirements for the mechanical characteristics of the profile in the range from + 350 ° C to + 530 ° C. In the process of pressing, the workpiece is in an electrically heated container. The temperature of the container is set at 10 ° C-20 ° C below the heating temperature of the workpiece to remove excess heat due to the work of deformation from the deformation zone (OCHPZ) in order to prevent deformation burnout. The pressing speed (the rate of metal outflow from the die channel during pressing) can also vary depending on the plastic characteristics of the alloy and the equipment of the press lines (for example, the presence of a pulling device - puller in the press line) in the range from 0.3 m / min to 40 m / min

In a preferred embodiment of the method, each rail bearing profile is made in the form of an I-beam of aluminum alloy, one shelf of which is the sole of the rail, the other shelf is its head, the front surface of which is designed to install a steel contact plate on it.

At the second stage, thermoadjoint processing of pressed semi-finished product (rail bearing profiles) is carried out. Processing is carried out in order to bring the geometric and mechanical characteristics of rail bearing profiles to the requirements of technical specifications. For profiles made of thermally unstrengthened alloys of the 1XXX, ZXXX, 5XXX series, stretch dressing is carried out with a degree of residual deformation from 0.3% to 3.5% in order to obtain the necessary dimensions, straightness, and relieve internal stresses after hot deformation. For alloys of the indicated series, incomplete or complete annealing can be used to obtain a more equilibrium structure and reduce the electrical resistance of the material. The permissible annealing temperature range for these materials depending on the grade of alloy is in the range from + 300 ° C to + 500 ° C. For profiles made of alloys of the 2XXX series (Al - Cu - Mg - Mn group), quenching is used in stationary furnaces from a temperature of + 490 ° C - + 500 ° C with subsequent straightening by stretching (with a degree of permanent deformation from 1.0% to 3.5 %) and natural aging at room temperature (+ 20 ° C) for 96 hours. The natural aging of alloys of the 2XXX series (Al - Cu - Mg - Mn group) is carried out in order to increase corrosion resistance. For profiles made of alloys of the 6XXX series (Al - Mg - Si group), depending on the requirements of technical specifications and current characteristics in the contact network of transport systems, quenching from the deformation temperature at the exit table of the press line or quenching in stationary furnaces with subsequent straightening by stretching (with the degree of permanent deformation from 0.3% to 3.5%) and artificial or natural aging. Artificial aging is carried out only in stationary electric furnaces with forced air circulation in two one-step modes: 1) heating to a temperature of + 190 ° C ... + 200 ° C followed by exposure to 2-4 hours and cooling in still air, or 2) heating to a temperature of + 160 ° C ... + 170 ° C followed by an exposure of 10-12 hours and cooling in calm air. Natural aging is carried out with aging at room temperature (+ 20 ° C) for 240-360 hours. For low- and medium-alloyed alloys of the 7XXX series, quenching from deformation temperature at the exit table of the press line or quenching in water from stationary furnaces from a temperature of + 400 ° C ... + 470 ° C can be used. For low- and medium-alloyed alloys of the 7XXX series (Al - Zn - Mg group), after softening by stretching with a degree of residual deformation of 0.3% to 3.5%, "softening" artificial aging according to a two-stage regime should be applied to increase corrosion resistance and lower electrical resistance. First stage: heating temperature + 100 ° C, holding time 6-12 hours. Second stage: heating temperature from + 160 ° C to + 190 ° C and the shutter speed which is selected individually depending on the alloy grade and chemical composition.

At the third stage, rail bearing profiles are connected from the side of the front surfaces of their heads to steel plates by explosion welding. The third stage includes the following operations: 1) preparation of the surface of the steel sheet: mechanical cleaning, applying grooves to initiate sheet trimming during explosion welding and chemical degreasing of the surface; 2) assembly of a package of rail bearing profiles from 2 to 20 pieces with strapping around the perimeter; 3) preparation of a horizontal platform with a sand cushion for installing the package: leveling the surface and ramming the cushion; 4) installation of a package of rail bearing profiles on a prepared horizontal platform with the indicated cushion; 5) installation of a steel sheet on a bag with a gap relative to the front surfaces; 6) preparation of explosives; 7) installation of the container on a steel sheet for explosive and uniform filling of explosive into it; 8) installation of the detonator (the place can be any on the surface of the explosive); 9) initiation of explosive charge, explosion welding; 10) disassembly of the package; 11) stripping the edges of the rails; 12) straightening of rails if necessary; 13) trim end defects.

An example implementation of the method is illustrated by the accompanying drawings.

Preliminarily, by the method described above (first stage), a plurality of rail bearing profiles are made of an aluminum alloy, for example two I-beams 1 and 5 (see the attached figure). Each such rail bearing profile, being an I-beam, has two shelves and a wall. One shelf of each rail bearing profile (positions 2 and 6, respectively for profiles 1 and 5) is the head of this profile with the corresponding front surface 3 or 7, designed for explosion welding of a steel contact plate. This head (2 or 6), to which a steel contact plate is welded, is at the same time the head of a bimetal steel-aluminum contact rail made of this rail bearing (I-beam) profile. The second shelf of each rail bearing profile (positions 4 and 8, respectively for profiles 1 and 5) is the sole of a bimetallic steel-aluminum contact rail. Rail bearing profiles 1 and 5, after appropriate preparation described above (second stage), are installed with soles 4 and 8 on a damping pad 9 made of river sand evenly applied to a solid horizontal platform 10. These profiles 1 and 5 are installed parallel to each other and with a minimum distance from each other. In this case, between the walls of profiles 1 and 5, an inner tab (beam) 11 of a rectangular cross-section of a material harder than the material of profiles 1 and 5 is located. The width of the tab 11 is selected so as to provide a gap between the heads 2 and 6, in which an additional tab 12 of rectangular cross-section, made of the same material as tab 11. The height of tab 11 is chosen so that this tab props from the bottom of head 2 and 6 of profiles 1 and 5 (i.e., serves as a support for these heads). The height of the tab 12 is chosen so that its upper plane is below the front surfaces 3 and 7. In addition, on the other sides of the walls of the profiles 1 and 5, outer tabs (not shown) are installed, similar to the inner tab 11 and intended only to perform the function of support for the heads 2 and 6. The package of rail bearing profiles thus formed is tied around the outside with tape to give it the necessary stability. After that, on the front surfaces 3 and 7 of the heads 2 and 6 of the rail bearing profiles 1 and 5, restrictive elements 13 of material either of the same as the material of profiles 1 and 5 or of a softer material are installed. A pre-prepared single steel sheet 14 is laid on these restrictive elements (i.e., a sheet whose area with a reserve overlaps the sum of the areas of the front surfaces 3 and 7 of the rail bearing profiles 1 and 5). The restrictive elements 13 define the design clearance between the front surfaces 3 and 7, on the one hand, and the lower surface of the steel sheet 14, on the other hand. Then, explosive 15 is uniformly poured onto the upper surface of the steel sheet 14 into the container (the dimensions of the container ensure compliance with the technological parameters of explosion welding), a detonator (not shown) is installed at the selected initiation site.

Then they carry out explosion welding, as a result of which the following technological operations are simultaneously and automatically carried out:

- connection at the level of metal bonds of the steel sheet 14 with the heads 2 and 6 of the rail bearing profiles 1 and 5 from the side of their front surfaces 3 and 7;

- cutting the steel sheet 14 in the gap between the heads 2 and 6 into corresponding strips, which, being welded to the heads 2 and 6, are the desired steel contact plates.

Thus, at the time of the explosion, multiple bimetallic steel-aluminum contact rails are simultaneously formed (diffusion welding of steel sheet 14 with many rail bearing profiles 1 and 5 and cutting of steel sheet 14 along the gaps between heads 2 and 6), which significantly increases labor productivity in the manufacturing process specified rails.

Claims (1)

A method of manufacturing a bimetallic steel-aluminum contact rails, each of which contains a rail bearing profile made of aluminum or its alloy and includes a head for placing a steel contact plate on it, as well as a steel contact plate connected to the head, characterized in that the pre-made rail bearing profiles stack parallel to each other on a horizontal platform with the front surfaces of their heads up with a gap between the heads of adjacent rail bearing profiles she and with the placement between the walls of adjacent rail bearing profiles of the tabs, the height of which is selected from the conditions of support for the specified heads, while the said tabs are made of material harder than the material of the rail bearing profile, and then placed with a gap relative to the front surfaces of the laid rail bearing profiles a single steel sheet that covers all these front surfaces, then explosives are poured over the entire area of the steel sheet, it is initiated and welded ku by explosion of a steel sheet to the heads of rail bearing profiles with the formation on these heads of steel contact plates.

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