CA2204928A1 - Method for heat treatment of a rail joint which is produced by fusion welding, and a burner arrangement which is intended for use in such a method - Google Patents
Method for heat treatment of a rail joint which is produced by fusion welding, and a burner arrangement which is intended for use in such a methodInfo
- Publication number
- CA2204928A1 CA2204928A1 CA002204928A CA2204928A CA2204928A1 CA 2204928 A1 CA2204928 A1 CA 2204928A1 CA 002204928 A CA002204928 A CA 002204928A CA 2204928 A CA2204928 A CA 2204928A CA 2204928 A1 CA2204928 A1 CA 2204928A1
- Authority
- CA
- Canada
- Prior art keywords
- rail
- region
- center plane
- burners
- heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/38—Torches, e.g. for brazing or heating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K23/00—Alumino-thermic welding
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B31/00—Working rails, sleepers, baseplates, or the like, in or on the line; Machines, tools, or auxiliary devices specially designed therefor
- E01B31/02—Working rail or other metal track components on the spot
- E01B31/18—Reconditioning or repairing worn or damaged parts on the spot, e.g. applying inlays, building-up rails by welding; Heating or cooling of parts on the spot, e.g. for reducing joint gaps, for hardening rails
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/26—Railway- or like rails
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- General Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Heat Treatment Of Articles (AREA)
- Machines For Laying And Maintaining Railways (AREA)
- Butt Welding And Welding Of Specific Article (AREA)
Abstract
In order to improve the heating efficiency, to reduce the fuel consumption, to reduce the labor time and to improve the quality of the material joint in the region of a thermit welded joint between two rail ends, it is proposed that, immediately after the fusion welding, in particular using the residual heat which is still present, the joint region, that is to say the fused structure including the structure of the heat affected zones which are adjacent on both sides, be subjected to normalization treatment. A burner arrangement for carrying out this method is characterized by a symmetrical distribution of burners (18, 11, 20, 21) with respect to a longitudinal center plane (22) and a transverse center plane (14), two burners being intended and arranged for treating the head flanks in the region of the fused structure, and in each case four burners being intended and arranged for treating the rail foot (2) in the region of the heat affected zones. The heat treatment is carried out using different cooling rates for the rail head (7) and for the rail foot (2) on the basis that the result is a structure which has a running surface with improved wear resistance and a rail foot (2) which has increased ductility.
Description
CA 02204928 1997-0~-09 ELEKTRO-THERMIT GmbH
Method for heat treatment of a rail joint which is produced by fusion welding, and a burner arrangement which is intended for use in such a method The invention relates to a method according to the pre-characterizing clause of claim 1.
The invention furthermore relates to a burner arrangement which is intended for use in the course of such a method.
The~use of thermit welding methods to produce a welded joint between two rail ends leads, as is known, to a cast steel structure in the joint region, which structure is composed of thermit-produced steel and rail steel dissolved therein, there being heated zones on both sides of this fused structure having a characteristic structural formation, which formations in each case merge continuously into the rail regions which have not been influenced by the welding process.
The structural formation takes place mainly as a function of the time profile of the temperature field which is formed in the rail body as a consequence of the welding process, in particular the locally different heating rates, temperatures and cooling rates. Thus, for example, a structure is located in the immediate vicinity of that region of the heat affected zones which are melted as a consequence of the welding process, which structure is coarse-grained, hard and pearlitic as a result of the severe overheating, this region being adjoined - looking in the direction away from the welded joint within the heated zone - by regions of decreasing hardness, to be precise as far as - those regions in which minimal hardness formation arises as a result of the perlite spheroidizing and the rail regions which are not influenced by the welding CA 02204928 1997-0~-09 process only following on after these virtually soft-annealed regions. The locally reduced hardness and thus wear resistance of the rail joint makes it necessary to carry out heat treatment after the welding process, depending on the extent of the hardness differences and the respectively used rail steel.
For example, self-hardening steels having a minimum strength of 900N/mm2 and a hardness of 260 HV to 280 HV
are used as the rail steel, their alloying components being composed mainly of carbon and manganese. Special quality classes of these self-hardening steels, formed by the addition of other alloying components such as chromium and vanadium, are also used, these steels having a minimum strength of llOON/mm2 and a hardness of 310 HV to 330 HV. Furthermore, self-hardening steels whose strength and hardness have been improved further by special heat treatment methods are also used. These comprise finely pearlitized steels whose hardness has been increased either only in the regions of the rail head which are severely stressed in track, or entirely, up to values of 350 HV to 400 HV. The structural change mentioned initially as a consequence of the welding process now has a different effect, to be precise depending on the specific rail steel used.
DE 43 19 417 C1 discloses a method for the fusion welding of head-hardened fine-pearlitic rails, in which, once steel produced by thermit welding has been included in the casting mold which surrounds the end faces of the rail ends to be joined, to be precise after the welded material has cooled down, the running surface of the weld and the adjacent heat affected zones are heated from above by means of a burner system for a short time period of 50 s to 150 s, the burning area of the burner system used being positioned at a distance from the running surface of the weld, which distance is a function of the weight per meter of the rail. The aim is to achieve fine pearlitization of the -CA 02204928 1997-0~-09 welding material and of the adjacent heat affected zones, and to make the hardness profile more uniform between the welding material and those regions of the rails which have not been influenced by -the welding process. As a result of the fact that the heat required for heat treatment is transferred extremely quickly, inter alia during a predetermined time interval, via the running surface of the rail to be treated, a defined temperature gradient is achieved in the vertical direction, so that the depth of that region where the steel is austenitic and which extends from the top surface of the rail is defined by the parameters which characterize the heat transfer.
Dispensing with the use of an external cooling means, cooling takes place directIy through the cold regions of the rail body itself. A fine-pearlitic structure is formed and, in particular, the hardness profile and thus the wear resistance are made uniform, in the surface region of the rail head - extending beyond the welded joint in the longitudinal direction of the rails.
Finally, the documents US 5 306 361 and 5 377 959 ~ disclose a method and an apparatus for heat treatment of such welded joints after the welding has been carried out, thermit being inserted in a mold which completely surrounds the welded joint, and the amount of heat which is to be introduced into the rail profile being controlled such that the steel is made austenitic, quenching subsequently being carried out using compressed air. This method thus leads to complete normalization of the rail profile at least in the regions close to the surface.
The aim of the above heat treatment methods is to make the material characteristics uniform beyond the welding joint, in particular to match the material characteristics to those of the rail material outside the welded joint. This refers in particular to CA 02204928 1997-0~-09 characteristics such as tensile strength and hardness.
The essential feature of the known heat treatment methods is that the welded joint is first of all cooled virtually down to ambient temperature, the structural regions to be treated subsequently being heated and cooled in accordance with a temperature/time function.
This means that the heat which is still contained in the welding material and the heat affected zones as a consequence of the welding process remains essentially unused. In addition to an increased time requirement as a result of the cooling process, this method of operation is also characterized by increased fuel consumption because of the renewed heating to above the temperature at which the steel becomes austenitic.
The stresses on the rail joint in the region of the rail foot, which result from the track use, comprise a bending oscillating stress with correspondingly alternating tensile stresses.
The object of the invention is to design a method of the type mentioned initially which leads to a welded joint which is appropriate for the stresses and is characterized, in comparison with the described prior art, by a shorter time requirement and improved heat efficiency. This object is achieved in the case of such a method by the features of the characterizing part of claim 1.
According to this, the essential feature of the invention is that the heat treatment starts immediately after the thermit welding process, that is to say after a mold head has been removed, the risers have been cut off and, if necessary, after carrying out the grinding work, that is to say at a time at which the welded joint region still contains a considerable amount of residual heat, but is at a temperature that is less than the temperature at which the steel becomes austenitic. The introduction of heat in order to make CA 02204928 1997-0~-09 the steel austenitic again, specifically with the aim of achieving a fine-grained austenitic structure, can in this way be limited quantitatively to the use of the said residual heat. The reduced fuel consumption in the course of this heat treatment and the improved utilization of the heat which has to be introduced into the joint region in order to carry out the welding process lead to considerably improved heat efficiency of the overall welding method, to reduced fuel consumption and, accordingly, to reduced costs. The heat treatment, namely normalization, is carried out at least in the region of the rail foot in order to eliminate coarse-grained elements which are present here both in the region of the fused structure and in the heat affected zones which are adjacent on both sides, and to replace them by a fine-grained normalized structure which can withstand the stresses of the track use, particularly with respect to its ductility characteristics.
This heat treatment of the joint region is followed by cooling to ambient temperature, final grinding and removal of the foot risers and the remains of the mold.
The unfavorable residual stress distribution which is produced as a result of the welding process can furthermore be at least partially overcome by a heat treatment method according to the invention.
The features of claim 2 are directed at extending the region to be normalized, to be precise to the region of the rail foot and of the rail head. The heat treatment of the flanks of the rail head in practice results in normalization of the running surface, however, because of the fast propagation of the temperature field which is produced.
The features of claims 3 and 4 are directed at different forms of cooling the heated austenitic joint CA 02204928 1997-0~-09 region. In principle, the cooling can be carried out in stationary ambient air - but a quenching treatment, for example using compressed air, is also feasible depending on the achievable cooling rates and the desired surface hardnesses.
The features of claims 5 and 6 are directed at further detailing a particularly advantageous variant of the heat treatment method. The aim of this type of method is also to control locally, in terms of its variation over time, the introduction of heat into the fused region, including the adjacent heat affected zones, as a function of the geometry of the rail profile, of the extent of the heat affected zones including the fused region, and of the temperature field which occurs within the rail body as a result of the heat conduction and heat propagation conditions in such a way as to produce structural conversions which give the rail joint region the macroscopically desired characteristics, the main aspects of which are adequate ductility and, in the region of the rail head, in particular the running surface, sufficient hardness and resistance to fracture propagation. The three-dimensional distribution of the introduction of heat in the region of the rail joint, the amount of heat introduced locally and the time for which the heat is introduced are available as parameters for controlling the temperature field, the last-mentioned parameter being used in particular to control the depth to which it is intended to bring about a structural conversion.
The cooling can take place via the remaining "cold"
rail body, stationary ambient air and, if required, via a quenching treatment which acts at least locally. The aim of the treatment in each case is to replace a coarse-grained structure produced by the welding process, at least at the points envisaged for this purpose, by a fine-grained normalized structure, whose strength and ductility characteristics have in consequence been improved. The basic method steps which CA 02204928 1997-0~-09 are associated with this normalization, namely rapid heating to a temperature slightly above the temperature at which the steel becomes austenitic, and maintaining this temperature until a fine-grained austenitic structure is formed, with subsequent rapid cooling, are known in principle and will not be described in more detail here as well.
It is furthermore the object of the invention to design an apparatus which is suitable for use for the purposes of the method according to the invention and which can be handled easily, particularly at the installation site. This object is achieved in the case of such an apparatus by the features of the characterizing part of claim 7.
The essential feature of the invention according to this is that the burners are distributed symmetrically with respect to two mutually perpendicular planes and that they are connected to a distributor tube which is used to convey a combustible gas mixture. This apparatus is used in such a manner that the apparatus is positioned such that the transverse center plane coincides with the corresponding center plane of the fused region, which ensures the required symmetry characteristics for introducing heat into the rail joint region, because of the burner arrangement. The apparatus is preferably intended to be placed onto parts of the rail profile, since this ensures that defined distances are reproducibly set between the nozzle arrangements of the burners and the surface sections of the rail profile which are to be heated.
The features of claims 8 to 11 are directed at the three-dimensional distribution of the burners, the fused region being heated by means of two burners which act on the head flanks of the rail head, and the heating of the rail foot region being brought about by CA 02204928 1997-0~-09 means of burners which are respectively directed at the heated zones on either side of the fused region.
The supporting elements according to the features of claim 12 as well as the spacers according to the features of claim 13, in conjunction with a rail profile, result in heat transfer conditions which are always reproducible in the region of the rail joint, and thus make it easy to carry out on-site work.
A burner arrangement which is suitable for use for the purposes of the mèthod according to the invention will be described in more detail in the following text with reference to the exemplary embodiment shown in the drawing, in which:
Fig. 1 shows an end view of a burner arrangement according to the invention placed onto a rail profile;
Fig. 2 shows a plan view of the burner arrangement according to arrow II in Fig. 1;
Fig. 3 shows a side view of the burner arrangement according to arrow III in Fig. 2.
1 designates the rail profile to be treated, in particular the joint region between two rail ends, whose respective rail foot 2 rests, in a manner not illustrated in the drawing, on the track bed via ties.
This thus comprises a laid track, on which the burner arrangement can be used.
The burner arrangement comprises a distributor tube 3, which is designed to carry a combustible gas mixture, composed, for example, of propane and oxygen, on one end 4 of which distributor tube 3 a gas connection 5 is fitted, and whose end 6 opposite the end 4 is of closed design. The distributor tube 3 extends horizontally at a distance above the rail head 7 and is supported with CA 02204928 1997-0~-09 g respect to the rail profile in a manner which will be explained in the following text.
Two branching tubes, 8, 9 are connected to the distributor tube 3 and each lead to burners 10, 11 whose outlet openings are assigned to the head flanks 12, 13 of the rail head 7 and are held at a defined distance from said flanks. The branching tubes 8, 9 as well as the burners 10, 11 extend essentially on a transverse center plane 14, which at the same time forms the plane of symmetry of the fused region 15, adjoined on both sides by the heated zones of the weld - not shown in the drawing. Further branching tubes 18, 19, at whose ends burners 20, 21 are in turn arranged, extend in each case on both sides of the transverse center plane 14, to be precise symmetrically with respect to it, in planes 16, 17. The arrangement of the branching tubes 8, 9 as well as 18, 19 alongside the associated burners 20, 21 is of symmetrical design with respect to a vertical longitudinal center plane 22 of the rail profile 1.
The burners 20, 21 are furthermore arranged such that their respective outlet directions point directly at the heated zones on both sides of the fused region 15, to be precise in a region adjacent to the rail foot 2.
The burners 20, 21 furthermore have two burner surfaces which extend at an angle to one another, are in each case provided with outlet nozzles, and whose orientation is essentially matched to the orientation of the opposing surfaces of the rail foot and of the web region directly adjacent to the rail foot 2.
23 designates supporting elements which are in each case fitted to the housings of the burners 21 and are intended to stand on facing surfaces of the rail foot 2. Identical supporting elements 24 are arranged on the opposite burners 21. The totality of these supporting elements 23, 24 forms a support for the burner CA 02204928 1997-0~-09 arrangement according to the invention, which support is symmetrical with respect to the planes 14, 22.
Furthermore, 25, 26 designate web-like spaces which extend originating from the sides facing the rail profile 1 of all the branching tubes 18, 19 and are intended to rest on the head flanks 12, 13. A
compensating mass 27 which is fitted to the end 6 of the distributor tube 3 is used to further ensure the stability of the burner arrangement.
The distribution and arrangement of the burners which are used on different surface regions of the welded joint are - as can be seen from the above statements -symmetrical with respect to the two planes 22, 14. Thedistance between the surfaces of the burner nozzles and the opposing surfaces of the rail profile, the amount of the gas mixture which can be burnt to carry out the heat treatment method, in this case the normalization, and which is passed via the distributor tube 3, and thus the heat to be transferred as well as the time duration of the heat transfer are controlled as a function of the residual heat in the rail profile as a result of the preceding welding process.
Method for heat treatment of a rail joint which is produced by fusion welding, and a burner arrangement which is intended for use in such a method The invention relates to a method according to the pre-characterizing clause of claim 1.
The invention furthermore relates to a burner arrangement which is intended for use in the course of such a method.
The~use of thermit welding methods to produce a welded joint between two rail ends leads, as is known, to a cast steel structure in the joint region, which structure is composed of thermit-produced steel and rail steel dissolved therein, there being heated zones on both sides of this fused structure having a characteristic structural formation, which formations in each case merge continuously into the rail regions which have not been influenced by the welding process.
The structural formation takes place mainly as a function of the time profile of the temperature field which is formed in the rail body as a consequence of the welding process, in particular the locally different heating rates, temperatures and cooling rates. Thus, for example, a structure is located in the immediate vicinity of that region of the heat affected zones which are melted as a consequence of the welding process, which structure is coarse-grained, hard and pearlitic as a result of the severe overheating, this region being adjoined - looking in the direction away from the welded joint within the heated zone - by regions of decreasing hardness, to be precise as far as - those regions in which minimal hardness formation arises as a result of the perlite spheroidizing and the rail regions which are not influenced by the welding CA 02204928 1997-0~-09 process only following on after these virtually soft-annealed regions. The locally reduced hardness and thus wear resistance of the rail joint makes it necessary to carry out heat treatment after the welding process, depending on the extent of the hardness differences and the respectively used rail steel.
For example, self-hardening steels having a minimum strength of 900N/mm2 and a hardness of 260 HV to 280 HV
are used as the rail steel, their alloying components being composed mainly of carbon and manganese. Special quality classes of these self-hardening steels, formed by the addition of other alloying components such as chromium and vanadium, are also used, these steels having a minimum strength of llOON/mm2 and a hardness of 310 HV to 330 HV. Furthermore, self-hardening steels whose strength and hardness have been improved further by special heat treatment methods are also used. These comprise finely pearlitized steels whose hardness has been increased either only in the regions of the rail head which are severely stressed in track, or entirely, up to values of 350 HV to 400 HV. The structural change mentioned initially as a consequence of the welding process now has a different effect, to be precise depending on the specific rail steel used.
DE 43 19 417 C1 discloses a method for the fusion welding of head-hardened fine-pearlitic rails, in which, once steel produced by thermit welding has been included in the casting mold which surrounds the end faces of the rail ends to be joined, to be precise after the welded material has cooled down, the running surface of the weld and the adjacent heat affected zones are heated from above by means of a burner system for a short time period of 50 s to 150 s, the burning area of the burner system used being positioned at a distance from the running surface of the weld, which distance is a function of the weight per meter of the rail. The aim is to achieve fine pearlitization of the -CA 02204928 1997-0~-09 welding material and of the adjacent heat affected zones, and to make the hardness profile more uniform between the welding material and those regions of the rails which have not been influenced by -the welding process. As a result of the fact that the heat required for heat treatment is transferred extremely quickly, inter alia during a predetermined time interval, via the running surface of the rail to be treated, a defined temperature gradient is achieved in the vertical direction, so that the depth of that region where the steel is austenitic and which extends from the top surface of the rail is defined by the parameters which characterize the heat transfer.
Dispensing with the use of an external cooling means, cooling takes place directIy through the cold regions of the rail body itself. A fine-pearlitic structure is formed and, in particular, the hardness profile and thus the wear resistance are made uniform, in the surface region of the rail head - extending beyond the welded joint in the longitudinal direction of the rails.
Finally, the documents US 5 306 361 and 5 377 959 ~ disclose a method and an apparatus for heat treatment of such welded joints after the welding has been carried out, thermit being inserted in a mold which completely surrounds the welded joint, and the amount of heat which is to be introduced into the rail profile being controlled such that the steel is made austenitic, quenching subsequently being carried out using compressed air. This method thus leads to complete normalization of the rail profile at least in the regions close to the surface.
The aim of the above heat treatment methods is to make the material characteristics uniform beyond the welding joint, in particular to match the material characteristics to those of the rail material outside the welded joint. This refers in particular to CA 02204928 1997-0~-09 characteristics such as tensile strength and hardness.
The essential feature of the known heat treatment methods is that the welded joint is first of all cooled virtually down to ambient temperature, the structural regions to be treated subsequently being heated and cooled in accordance with a temperature/time function.
This means that the heat which is still contained in the welding material and the heat affected zones as a consequence of the welding process remains essentially unused. In addition to an increased time requirement as a result of the cooling process, this method of operation is also characterized by increased fuel consumption because of the renewed heating to above the temperature at which the steel becomes austenitic.
The stresses on the rail joint in the region of the rail foot, which result from the track use, comprise a bending oscillating stress with correspondingly alternating tensile stresses.
The object of the invention is to design a method of the type mentioned initially which leads to a welded joint which is appropriate for the stresses and is characterized, in comparison with the described prior art, by a shorter time requirement and improved heat efficiency. This object is achieved in the case of such a method by the features of the characterizing part of claim 1.
According to this, the essential feature of the invention is that the heat treatment starts immediately after the thermit welding process, that is to say after a mold head has been removed, the risers have been cut off and, if necessary, after carrying out the grinding work, that is to say at a time at which the welded joint region still contains a considerable amount of residual heat, but is at a temperature that is less than the temperature at which the steel becomes austenitic. The introduction of heat in order to make CA 02204928 1997-0~-09 the steel austenitic again, specifically with the aim of achieving a fine-grained austenitic structure, can in this way be limited quantitatively to the use of the said residual heat. The reduced fuel consumption in the course of this heat treatment and the improved utilization of the heat which has to be introduced into the joint region in order to carry out the welding process lead to considerably improved heat efficiency of the overall welding method, to reduced fuel consumption and, accordingly, to reduced costs. The heat treatment, namely normalization, is carried out at least in the region of the rail foot in order to eliminate coarse-grained elements which are present here both in the region of the fused structure and in the heat affected zones which are adjacent on both sides, and to replace them by a fine-grained normalized structure which can withstand the stresses of the track use, particularly with respect to its ductility characteristics.
This heat treatment of the joint region is followed by cooling to ambient temperature, final grinding and removal of the foot risers and the remains of the mold.
The unfavorable residual stress distribution which is produced as a result of the welding process can furthermore be at least partially overcome by a heat treatment method according to the invention.
The features of claim 2 are directed at extending the region to be normalized, to be precise to the region of the rail foot and of the rail head. The heat treatment of the flanks of the rail head in practice results in normalization of the running surface, however, because of the fast propagation of the temperature field which is produced.
The features of claims 3 and 4 are directed at different forms of cooling the heated austenitic joint CA 02204928 1997-0~-09 region. In principle, the cooling can be carried out in stationary ambient air - but a quenching treatment, for example using compressed air, is also feasible depending on the achievable cooling rates and the desired surface hardnesses.
The features of claims 5 and 6 are directed at further detailing a particularly advantageous variant of the heat treatment method. The aim of this type of method is also to control locally, in terms of its variation over time, the introduction of heat into the fused region, including the adjacent heat affected zones, as a function of the geometry of the rail profile, of the extent of the heat affected zones including the fused region, and of the temperature field which occurs within the rail body as a result of the heat conduction and heat propagation conditions in such a way as to produce structural conversions which give the rail joint region the macroscopically desired characteristics, the main aspects of which are adequate ductility and, in the region of the rail head, in particular the running surface, sufficient hardness and resistance to fracture propagation. The three-dimensional distribution of the introduction of heat in the region of the rail joint, the amount of heat introduced locally and the time for which the heat is introduced are available as parameters for controlling the temperature field, the last-mentioned parameter being used in particular to control the depth to which it is intended to bring about a structural conversion.
The cooling can take place via the remaining "cold"
rail body, stationary ambient air and, if required, via a quenching treatment which acts at least locally. The aim of the treatment in each case is to replace a coarse-grained structure produced by the welding process, at least at the points envisaged for this purpose, by a fine-grained normalized structure, whose strength and ductility characteristics have in consequence been improved. The basic method steps which CA 02204928 1997-0~-09 are associated with this normalization, namely rapid heating to a temperature slightly above the temperature at which the steel becomes austenitic, and maintaining this temperature until a fine-grained austenitic structure is formed, with subsequent rapid cooling, are known in principle and will not be described in more detail here as well.
It is furthermore the object of the invention to design an apparatus which is suitable for use for the purposes of the method according to the invention and which can be handled easily, particularly at the installation site. This object is achieved in the case of such an apparatus by the features of the characterizing part of claim 7.
The essential feature of the invention according to this is that the burners are distributed symmetrically with respect to two mutually perpendicular planes and that they are connected to a distributor tube which is used to convey a combustible gas mixture. This apparatus is used in such a manner that the apparatus is positioned such that the transverse center plane coincides with the corresponding center plane of the fused region, which ensures the required symmetry characteristics for introducing heat into the rail joint region, because of the burner arrangement. The apparatus is preferably intended to be placed onto parts of the rail profile, since this ensures that defined distances are reproducibly set between the nozzle arrangements of the burners and the surface sections of the rail profile which are to be heated.
The features of claims 8 to 11 are directed at the three-dimensional distribution of the burners, the fused region being heated by means of two burners which act on the head flanks of the rail head, and the heating of the rail foot region being brought about by CA 02204928 1997-0~-09 means of burners which are respectively directed at the heated zones on either side of the fused region.
The supporting elements according to the features of claim 12 as well as the spacers according to the features of claim 13, in conjunction with a rail profile, result in heat transfer conditions which are always reproducible in the region of the rail joint, and thus make it easy to carry out on-site work.
A burner arrangement which is suitable for use for the purposes of the mèthod according to the invention will be described in more detail in the following text with reference to the exemplary embodiment shown in the drawing, in which:
Fig. 1 shows an end view of a burner arrangement according to the invention placed onto a rail profile;
Fig. 2 shows a plan view of the burner arrangement according to arrow II in Fig. 1;
Fig. 3 shows a side view of the burner arrangement according to arrow III in Fig. 2.
1 designates the rail profile to be treated, in particular the joint region between two rail ends, whose respective rail foot 2 rests, in a manner not illustrated in the drawing, on the track bed via ties.
This thus comprises a laid track, on which the burner arrangement can be used.
The burner arrangement comprises a distributor tube 3, which is designed to carry a combustible gas mixture, composed, for example, of propane and oxygen, on one end 4 of which distributor tube 3 a gas connection 5 is fitted, and whose end 6 opposite the end 4 is of closed design. The distributor tube 3 extends horizontally at a distance above the rail head 7 and is supported with CA 02204928 1997-0~-09 g respect to the rail profile in a manner which will be explained in the following text.
Two branching tubes, 8, 9 are connected to the distributor tube 3 and each lead to burners 10, 11 whose outlet openings are assigned to the head flanks 12, 13 of the rail head 7 and are held at a defined distance from said flanks. The branching tubes 8, 9 as well as the burners 10, 11 extend essentially on a transverse center plane 14, which at the same time forms the plane of symmetry of the fused region 15, adjoined on both sides by the heated zones of the weld - not shown in the drawing. Further branching tubes 18, 19, at whose ends burners 20, 21 are in turn arranged, extend in each case on both sides of the transverse center plane 14, to be precise symmetrically with respect to it, in planes 16, 17. The arrangement of the branching tubes 8, 9 as well as 18, 19 alongside the associated burners 20, 21 is of symmetrical design with respect to a vertical longitudinal center plane 22 of the rail profile 1.
The burners 20, 21 are furthermore arranged such that their respective outlet directions point directly at the heated zones on both sides of the fused region 15, to be precise in a region adjacent to the rail foot 2.
The burners 20, 21 furthermore have two burner surfaces which extend at an angle to one another, are in each case provided with outlet nozzles, and whose orientation is essentially matched to the orientation of the opposing surfaces of the rail foot and of the web region directly adjacent to the rail foot 2.
23 designates supporting elements which are in each case fitted to the housings of the burners 21 and are intended to stand on facing surfaces of the rail foot 2. Identical supporting elements 24 are arranged on the opposite burners 21. The totality of these supporting elements 23, 24 forms a support for the burner CA 02204928 1997-0~-09 arrangement according to the invention, which support is symmetrical with respect to the planes 14, 22.
Furthermore, 25, 26 designate web-like spaces which extend originating from the sides facing the rail profile 1 of all the branching tubes 18, 19 and are intended to rest on the head flanks 12, 13. A
compensating mass 27 which is fitted to the end 6 of the distributor tube 3 is used to further ensure the stability of the burner arrangement.
The distribution and arrangement of the burners which are used on different surface regions of the welded joint are - as can be seen from the above statements -symmetrical with respect to the two planes 22, 14. Thedistance between the surfaces of the burner nozzles and the opposing surfaces of the rail profile, the amount of the gas mixture which can be burnt to carry out the heat treatment method, in this case the normalization, and which is passed via the distributor tube 3, and thus the heat to be transferred as well as the time duration of the heat transfer are controlled as a function of the residual heat in the rail profile as a result of the preceding welding process.
Claims (13)
1. Method for heat treatment of a rail connection which is produced by fusion welding, in particular for the purpose of at least partial adjustment of a fine-grained normalized structure in the connection region, characterized - in that normalization in the connection region of the rail ends is carried out after the welding process, specifically using as far as possible the residual heat which is still present in the welded material and in the heat affected zones which are adjacent to the welded material on both sides, to be precise at least in the region of the rail foot (2).
2. Method according to claim 1, characterized - in that the normalization is also carried out in the region of the rail head (7).
3. Method according to claim 1 or 2 characterized - in that the normalization is carried out with the treated region/regions being cooled by stationary ambient air.
4. Method according to claim 1 or 2, characterized - in that the normalization is carried out with at least one treated region being cooled in the manner of quenching, for example using compressed air.
5. Method according to one of the preceding claims 1 to 4, characterized - in that the heat which must be introduced into the joint region for the purposes of normalization is transferred symmetrically in the longitudinal direction and lateral direction with respect to a fused region (15).
- in that heat transfer to the rail head (7) is carried out via the head flanks (12, 13) in the fused region (15), and - in that heat transfer to the rail foot (2) is carried out in the region of the heat affected zones on both sides of the fused region (15).
- in that heat transfer to the rail head (7) is carried out via the head flanks (12, 13) in the fused region (15), and - in that heat transfer to the rail foot (2) is carried out in the region of the heat affected zones on both sides of the fused region (15).
6. Method according to claim 5 characterized - in that the parameters which characterize the heat transfer, such as the heating rate, the holding time and the cooling rate, are selected on the basis that, in particular the wear resistance and fracture resistance of the rail head (7) and the ductility of the rail foot (2) are improved.
7. Apparatus for carrying out the method according to one of the preceding claims 1 to 6, in particular a burner arrangement, characterized by - a symmetrical distribution of burners (10, 11, 20, 21) with respect to a vertical longitudinal center plane (22) and a transverse center plane (14) which extends at right angles to it, - burners (10, 11, 20, 21) being continuously connected to a distributor tube (3) which has a gas connection (5) at one end (4), and - the apparatus being intended and designed to be placed onto the rail profile (1) to be treated or onto ground regions adjacent to it.
8. Apparatus according to claim 7 characterized - in that at least one burner (10, 11) on either side of the longitudinal center plane (22) in each case has an outlet direction lying in the transverse center plane (14).
9. Apparatus according to claims 7 or 8, characterized - in that the outlet direction of the burners (10,11) is directed towards the head flanks (12, 13) of the rail profile (1) to be treated.
10. Apparatus according to one of claims 7 to 9, characterized - in that at least one burner (20, 21) is provided on either side of the longitudinal center plane (21) and on either side of the transverse center plane (14), the outlet direction of which burner runs parallel to the transverse center plane (14), and at a distance from it.
11. Apparatus according to claim 10, characterized - in that the outlet directions of the burners (20, 21) are directed essentially at the rail foot (2) of the rail profile (1) to be treated, in the region of the heated zones.
12. Apparatus according to one of the preceding claims 7 to 11, characterized by - supporting elements (23) which are intended to stand on parts of the rail foot (2) on either side of the welded joint and are arranged symmetrically with respect-to the longitudinal center plane (22) and the transverse center plane (10).
13. Apparatus according to one of the preceding claims 7 to 12 characterized - in that the burners (10, 11, 20, 21) are connected to the distributor tube (3) via branching tubes (8, 9, 18, 19), and - in that spacers (25, 26) supported on the rail profile (1) are provided in order to keep the burner at a defined distance from that surface of the rail profile (1) which is to be heated.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19619171.8 | 1996-05-11 | ||
| DE19619171A DE19619171C1 (en) | 1996-05-11 | 1996-05-11 | Method of heat treatment of welded connections of rail tracks |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2204928A1 true CA2204928A1 (en) | 1997-11-11 |
Family
ID=7794135
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002204928A Abandoned CA2204928A1 (en) | 1996-05-11 | 1997-05-09 | Method for heat treatment of a rail joint which is produced by fusion welding, and a burner arrangement which is intended for use in such a method |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH1053816A (en) |
| CA (1) | CA2204928A1 (en) |
| DE (1) | DE19619171C1 (en) |
| EA (1) | EA000181B1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10041671B2 (en) | 2012-10-23 | 2018-08-07 | Linde Aktiengesellschaft | Multi-flame burner and method for heating a workpiece |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT6941U3 (en) * | 2004-02-23 | 2005-03-25 | Plasser Bahnbaumasch Franz | WELDING UNIT FOR WELDING TWO RAILS OF A TRACK AND METHOD |
| DE102006061800A1 (en) * | 2006-12-21 | 2008-06-26 | Linde Ag | Device for flame straightening |
| JP5042696B2 (en) * | 2007-04-17 | 2012-10-03 | 新日本製鐵株式会社 | Heating device and heating method for rail joint member made of shape memory alloy |
| CA2756082C (en) * | 2009-03-27 | 2014-06-17 | Nippon Steel Corporation | Device and method for cooling rail weld zone |
| CN102409585B (en) * | 2011-08-16 | 2015-04-22 | 中铁二十二局集团第二工程有限公司 | Cooler for cooling on-site welded joint of long steel rail and using method for cooler |
| DE102012020801A1 (en) * | 2012-10-23 | 2014-04-24 | Linde Aktiengesellschaft | Multi-flame burner and method for heating a workpiece |
| RU2556257C2 (en) * | 2013-08-05 | 2015-07-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Иркутский государственный университет путей сообщения" | Thermal processing of rail head working surface |
| CN103643604B (en) * | 2013-12-18 | 2015-10-21 | 西南交通大学 | A kind of line lock welding and heat treatment monommechanization operation construction method |
| FR3066508B1 (en) * | 2017-05-22 | 2021-02-12 | Matisa Materiel Ind Sa | PROCEDURE FOR LAYING A RAILWAY RAIL, INCLUDING HEATING OF THE RAIL, AND WORK TRAIN FOR IMPLEMENTING THE LAYING PROCEDURE |
| CN110607721A (en) * | 2019-09-23 | 2019-12-24 | 西南交通大学 | Movable steel rail double-frequency normalizing mechanism with air spraying function |
| CN114774652B (en) * | 2022-04-29 | 2024-07-23 | 重庆长征重工有限责任公司 | 17CrNiMo6 material preliminary heat treatment method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU432215A1 (en) * | 1971-08-27 | 1974-06-15 | М. Макара, А. Е. Еринов, В. А. Сорока, В. Д. Ковалев, | INSTALLATION FOR EXTERNAL LOCAL HEAT-TREATMENT OF RINGAL HEATED APPLICATION COMPONENTS 12 The invention relates to devices for local extra-heating heating: metal, in particular, devices for external heating of hot-gauge steel vessels of thick-walled steel vessels, and for the treatment of large-sized steel vessels that have been applied to you by the local thick-walled steel vessels. connections, consisting of a collapsible framework mounted directly on the welded joint, a series of evenly arranged flameless burners and those spreading plates. The purpose of the invention is to automate the process, as well as increasing the production -10 ^ c x x with a section along A — A. The installation includes a wave stand 7, on which the article being heated 2. The self-propelled portal 3 is equipped with a crossmember 4, to which A gas-junction-nagging device is hinged, consisting of separate heaters 5. Chi: The heater of the heater is detected by an irrimeter of the item being heated. The traverse has vertical non-tendency to lead] 1'of the diameter difference ^ max - Omlle- Two electric winchs with cargo ropes 7 are mounted on the traverse. The gas supply system is made of flexible metal sleeves 8. Extendable heating and economy of heating. This is up to 15 9 moved vertically to position |
| SU515814A1 (en) * | 1973-03-05 | 1976-05-30 | Предприятие П/Я В-2120 | Installation for heat treatment of ring welds |
| JPS5519297B2 (en) * | 1973-07-31 | 1980-05-24 | ||
| SU737167A1 (en) * | 1978-01-05 | 1980-05-30 | Центральный Ордена Трудового Красного Знамени Научно-Исследовательский Институт Черной Металлургии Им.И.П.Бардина | Method of manufacturing welding articles |
| SU1217896A1 (en) * | 1984-03-21 | 1986-03-15 | Магнитогорский Дважды Ордена Ленина,Ордена Октябрьской Революции И Ордена Трудового Красного Знамени Металлургический Комбинат Им.В.И.Ленина | Method of machining weld joints of steel strips |
| US5303361A (en) * | 1989-01-18 | 1994-04-12 | Lotus Development Corporation | Search and retrieval system |
| US5306361A (en) * | 1992-10-02 | 1994-04-26 | Besch Gordon O | Method for improving service life of rail welds by aluminothermic heat treatment |
| DE4319417C1 (en) * | 1993-06-11 | 1994-08-04 | Elektro Thermit Gmbh | Insert-cast welding of fine-pearlitic rails |
-
1996
- 1996-05-11 DE DE19619171A patent/DE19619171C1/en not_active Expired - Fee Related
- 1996-11-06 EA EA199600089A patent/EA000181B1/en not_active IP Right Cessation
-
1997
- 1997-05-09 CA CA002204928A patent/CA2204928A1/en not_active Abandoned
- 1997-05-09 JP JP9119348A patent/JPH1053816A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10041671B2 (en) | 2012-10-23 | 2018-08-07 | Linde Aktiengesellschaft | Multi-flame burner and method for heating a workpiece |
Also Published As
| Publication number | Publication date |
|---|---|
| EA000181B1 (en) | 1998-12-24 |
| DE19619171C1 (en) | 1997-05-28 |
| EA199600089A1 (en) | 1997-12-30 |
| JPH1053816A (en) | 1998-02-24 |
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