EP0545336B1 - Head to head welding joint of two aligned rail segments - Google Patents

Abstract

The invention describes the welding connection (5) as well as a method for its manufacture. The mutually facing end sides (6, 7) of the rail segments (1, 2) are interconnected via an added material (8) which extends from the rail foot (32) to the rail head (30). The welding connection (5) is formed by a welding zone (22; 23; 24, 25) connecting the rail foot (32), one connecting a rail web (31) and one connecting the rail head (30). The welding zones (22 to 25) are connected positively in contact regions (33 to 36) turned directly into one another. In addition, the welding zone (22) in the rail head (30) consists of fewer than 15 mutually adjacent, approximately parallel-running welding beads (26) which are melted into one another and preferably lie one above another. The welding zone (24, 25) in the rail foot (32) consists of fewer than 10 mutually adjacent, approximately parallel welding beads (28, 29) which are melted into one another. <IMAGE>

Description

The invention describes a welded joint as described in the preamble of claim 1 and a method for producing such a welded joint.

From US-A-4 672 173 a welding method for producing a welded connection between two rail pieces arranged one behind the other in the longitudinal direction of a rail track is known. In this known welding process, the protective gas is introduced into the mold cavity, which is formed by the rail profiles and the cooling device which extends over the region of the slot between the two rail gaps, and which is to be closed by the welding. The cooling device completely surrounds the rail gap and the welding device can only penetrate into the rail gap via an opening on the top of the cooling device. The disadvantage here is that the weld connection cannot be checked optically, which means that the entire weld seam must be re-established if the weld seam is faulty.

Furthermore, a welding method is known from US Pat. No. 4,841,116, in which the rail gap is in turn enclosed on all sides, and a welding powder is poured in via an opening at the top, which is melted by an arc produced by means of a welding wire, ie plasticized or is liquefied to fill the cavity between the two rails. The disadvantage of this welding process is that it is not possible to visually check the quality of the welding process when the weld is being made, and cavities, for example, which occur in the transition area between the melted or plasticized welding powder and the opposite end faces of the two rail pieces are not recognized can. This means that the direct penetration or melting of the base material of the rail sections is not guaranteed in all cases, and therefore the quality of those produced in this way In many cases, the weld connection is not sufficient, or the entire weld seam has to be re-established in the event of a malfunction of the method, since an error in the welding process can only be determined, for example, only after completion of the entire weld connection by means of an X-ray examination or the like.

A wide variety of methods for connecting the ends of immediately successive rail parts for rails of tracks for rail vehicles, for example railroad tracks or tramway rails, are already known. The so-called aluminum-thermite welding is often used for such connection welding, if this is done in the area of laid tracks. In this aluminum thermite welding, metal powder is melted and poured in the liquid state into a mold surrounding the rail ends, so that the gap between the mutually facing, opposite ends of the front ends of the rails is poured out in a type of casting process and is thereby connected to one another.

Flash butt welding is also used for the welding of rails in laid tracks, but above all for the production of connection welds in rail bearings. In this case, the unprocessed abutting surfaces are kept in such light contact during the passage of the current that the material burns continuously at the small local contact points because of the large current density. The liquid metal is thrown out of the joint. After sufficient depth of the burn-up zone, the welding is carried out by sudden upsetting with simultaneous power cut-off. A burr is created at the weld due to the liquid material squeezed out of the butt joint. This burr is removed by shearing and subsequent grinding.

Furthermore, in the area of track systems with high rail loads and wear, particularly in curved sections, it is customary to restore the rail head profile by cladding. For this purpose, additional materials are often applied to the rails, in particular in the area of the rail head flanks, using open or concealed arc welding or inert gas welding.

The desired rail head shape is then produced by grinding by removing the excess material.

The present invention is based on the object of creating a welded connection between two rail pieces arranged one behind the other in the longitudinal direction of a rail track, which is composed of several individual seams and can be produced both by hand and by automatic welding processes in a short time without complex machinery.

This object of the invention is achieved by the welded joint described in the characterizing part of patent claim 1. The advantage of this solution is that by arranging several welding zones in which the material thicknesses are approximately the same, the base materials can be melted sufficiently and an intimate connection between the base material and the additional materials can be produced. Above all, this makes it possible to connect and fill the thicker areas by means of a plurality of weld seams arranged next to and above one another. As a result, the total temperature load on the rail track, especially in the area of the weld, can be kept low and embrittlement in the weld area is avoided. Another advantage of this solution is that welding can now be carried out under a protective gas atmosphere, as a result of which oxygen access to the heated or plasticized areas of the rail can be prevented.

A further advantageous embodiment of the welded joint is described in claim 2. It is now possible to use more resistant and harder materials in the areas most exposed to wear, the layer thickness applied and the area in which these materials are used can now be freely selected and yet the welded connection can be made in a single operation.

An embodiment according to claim 3 is also advantageous, since it means the different stresses in the different areas the rail can also be taken into account when making the welded connection.

The embodiment variant according to claim 4 advantageously enables the welded connection to be produced by a multiplicity of layers of the same structure, as a result of which a uniform structure is achieved over the entire welded connection and a high strength of the welded connection can be achieved. In addition, by adapting or switching on different layers of different additional materials in the interior of the individual welding zones, for example reinforcement areas and reinforcement ribs or layers which promote stretching, high elastic shape change properties can be used.

The further development according to patent claim 5 makes it possible to avoid internal stress zones in the transition between materials with different elasticity, stretching or bending properties, since sudden changes in the individual strength values are prevented.

The invention also includes a method for producing a welded connection, as described in the preamble of claim 6.

This method is characterized by the features in the characterizing part of claim 6. It is advantageous in the production of the welded joint according to this method that by using the special welding gas to create the plasma, the gas atoms are dissociated into ions and free electrons or protective gas, the charged gas particles being heated to very high temperatures of, for example, 6,600 to 22,200 Degrees. By transferring the highly heated gas particles across the arc, the charged plasma particles give off their heat, which at the same time melts the melting electrode and heats up or preheats the base material. An excellent, short-term plasticization of the base material is thus achieved, which results in excessive and excessive heating of the edge areas in the transition between Prevents base material and additional material, which leads to embrittlement of the base material in the known methods.

The measures according to claim 7 are also advantageous, since local overheating of the base material can thereby be prevented in a targeted manner.

The further measures according to claim 8 enable an embrittlement-free construction of the welding zones by avoiding expansion cracks between the individual welding beads.

In the procedure according to claim 9, it is advantageous that the additional heat energy required can be kept low, since the welding zones can be produced in one operation without loss of heat in the rail pieces due to the manufacture of the weld beads in the previous welding zone.

If one proceeds according to claim 10, stress cracks or structural changes in the end regions of the welding beads of individual welding zones can be prevented that the welding beads lying one above the other or next to one another are produced as a continuous, one-piece part.

Finally, it is advantageous in the course of the method according to claim 11 that a layer-wise offset bond between the individual welding beads is produced in the welding zone, which enables a more favorable transmission of forces between the individual rail pieces.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawings:

Fig. 1

einen Schienenstoß in Seitenansicht während der Herstellung einer Schweißverbindung mit der dazugehörigen Schweißanlage in vereinfachter, schematischer Darstellung;

Fig. 2

eine Schweißverbindung zwischen zwei Stirnenden von zueinander fluchtend angeordneten Schienen in Stirnansicht und im Schnitt, gemäß den Linien II-II in Fig.3;

Fig. 3

die Schweißverbindung nach Fig.2 im Schnitt, gemäß den Linien III-III in Fig.2;

Fig. 4

die Schweißverbindung in Stirnansicht mit der im Schienenfußbereich angeordneten Schweißzone und der dieser Schweißzone zugeordneten Kühlvorrichtung, geschnitten, gemäß den Linien IV-IV in Fig.5;

Fig. 5

die Schweißverbindung nach Fig.4 in Seitenansicht;

Fig. 6

die Schweißverbindung in Stirnansicht mit den bereits fertiggestellten Schweißzonen im Bereich des Schienenfußes und des Schienensteges mit der dem Schienensteg zugeordneten Kühlvorrichtung, geschnitten, gemäß den Linien VI-VI in Fig.7;

Fig. 7

die Schweißverbindung nach Fig.6 in Seitenansicht;

Fig. 8

die Schweißverbindung in Stirnansicht mit allen fertig gestellten Schweißzonen und den dem Schienenkopf und dem Schienensteg zugeordneten Kühlvorrichtungen im Schnitt, gemäß den Linien VIII-VIII in Fig.9;

Fig. 9

die Schweißverbindung nach Fig.8 in Seitenansicht.

Show it:

Fig. 1

a rail joint in side view during the production of a welded connection with the associated welding system in a simplified, schematic representation;

Fig. 2

a welded connection between two ends of rails arranged in alignment with one another in front view and in section, according to lines II-II in Figure 3;

Fig. 3

the welded joint according to Figure 2 in section, according to lines III-III in Figure 2;

Fig. 4

the welded connection in front view with the welding zone arranged in the rail foot region and the cooling device assigned to this welding zone, cut, according to lines IV-IV in FIG. 5;

Fig. 5

the welded joint of Figure 4 in side view;

Fig. 6

the welded connection in front view with the already completed welding zones in the area of the rail foot and the rail web with the cooling device assigned to the rail web, cut according to the lines VI-VI in FIG. 7;

Fig. 7

the welded joint of Figure 6 in side view;

Fig. 8

the welded connection in front view with all completed welding zones and the cooling devices assigned to the rail head and the rail web in section, according to lines VIII-VIII in FIG. 9;

Fig. 9

the welded joint of Figure 8 in side view.

In Fig.1 two rail pieces 1,2 are shown, the longitudinal direction - arrow 3 - are aligned one behind the other and together form a rail track 4 for rail vehicles, such as trains, trams, funiculars, cranes, etc. The rail pieces 1, 2 are connected to one another in a non-positive and positive manner via a welded connection 5. For this purpose, an additional material 8 is introduced between the mutually facing end faces 6, 7 of the two rail pieces 1, 2 by melting off a melting electrode 9. The additional material 8 is melted off by means of an arc 10 built up between the melting electrode 9 and the rail section 1, 2, the access of oxygen and nitrogen to the welding point being prevented by a gas jacket 11 consisting of various protective gases 12, 13, 14.

The fusible electrode 9, which is formed, for example, by a welding wire with a corresponding diameter, is drawn off from a supply roll 15 and fed via a welding gun 16, via which the power supply via a line 17 and the supply of the protective gases 12 to 14 or the protective gas mixture, respectively a line 18 takes place. The welding gun 16 is equipped in accordance with the known designs and is designed with the necessary switches for initiating and interrupting the wire feed of the melting electrode 9 or the power supply or the supply of the protective gases 12 to 14 or protective gas mixture and is provided with a control device 19 and with a voltage supply device 20 and with a container for the protective gases 12 to 14 or the protective gas mixture, for example gas bottles 21, in connection.

The melting electrode 9 has a diameter between 0.8 and 4.0 mm for producing the intended welding zones, the voltage supply device 20 being designed to supply a current to the melting electrode 9 in the range from 100 to 1100 amperes. The protective gases 12 to 14, or the protective gas mixture produced therefrom, consist of 40% to 70% argon, 25% to 60% helium, 3% to 10% carbon dioxide and 0.1% to 1% oxygen.

The respective melting power or the current supply from the voltage supply device 20 is changed and controlled via the control device 19 such that between 400 and 1200 balls per second of the melting electrode 9 are melted, which preferably have a diameter which corresponds at least to the size of the diameter of the melting electrode 9.

With these previously specified criteria, it is now possible to use the advantages of the spray arc transmission method in conjunction with drop sizes that are normally assigned to the globular transmission method. As a result, in connection with the new welding gas mixture, the increased metal current flow volume can be retained in the welded joint via the plasma field thus achieved, and an improved quality of the welded joint and better penetration can be achieved through largely continued preheating of the base material.

2 and 3 show a welded connection between two rail sections 1 and 2, which consists of several welded zones 22, 23, 24 and 25. The welding zones 24 and 25 can also be formed by a common single welding zone.

As can be seen from the illustrations of the welding zones 22 to 25, each of these welding zones is formed by a plurality of welding beads 26, 27, 28 and 29. These welding beads 26 to 29 are, as the illustration in FIG. 3 in particular shows, arranged between the two facing end faces 6, 7 of the rail sections 1, 2 above and essentially parallel to one another. In each case 6 to 8, a maximum of 10 essentially parallel welding beads arranged one above the other form the welding zone 22 in the area of a rail head 30, while the welding beads 27 form the welding zone 23 in the area of a rail web 31 and the welding beads 28 and 29 form the welding zones 24 and 25 form in the region of a rail foot 32.

As shown schematically in the area of the rail foot 32, when the welding beads 28 and 29 lying one above the other are melted, the uppermost layer of the welding bead 28 and 29 underneath, indicated by dashed lines, melts. This results in an intimate material connection between the beads arranged one above the other Welding beads 26 to 29.

It can also be seen that the welding zones 22 to 25 are fused in the mutually facing contact areas 33, 34, 35 and 36 and thus there is a uniform structure in the different spatial directions of the rail sections 1, 2.

The contact area 34 is formed between the welding beads 27 and 29, the contact area 35 between the welding beads 27 and 28 and between the welding beads 28 and 29 in the area of the rail foot 32 the contact area 36. These contact areas 34 to 36 are shown schematically by dash-dotted lines and different types of hatching. However, it is also possible to design the welding zones 24 and 25 in the region of the rail foot 32 as a single welding zone, as is shown in more detail in a figure that follows later.

The advantage of this uniform structure is that uniform strength values can be achieved in the welded joint and the bending strength or tensile strength can thus be increased considerably.

At the same time, however, the impact strength is also increased, so that, especially in the area of rail joints, even if small notches form in the area of a running surface 37 of the rail head 30, the vibrations resulting from the impact stress due to the rolling of the wheels over the life of such a welded joint 5 not adversely changed.

With the design of the welded joint 5 according to the invention, it is possible, despite the increased heat supply due to the greater material removal and the improved melting of the base material of the rail sections 1, 2, to prevent the embrittlement of the base material of the rail sections 1 and 2 by in the area of the welded connection during manufacture of the individual welding zones 22 to 25 cooling devices can be arranged.

4 to 9, the cooling devices 38, 39 and 40 required for the production of the different welding zones 22 to 25 are shown in the arrangement required for this. At the same time, the sequence of the representations in FIGS. 4 to 9 results in the process sequence for producing the welded connection 5 according to the invention.

As can be seen from FIGS. 4 and 5, a weld gap 41 is produced between the end faces 6, 7 in which a spacer 42 is located in the region of the rail head before the weld connection 5 is made between the end faces 6 and 7 of the rail pieces 1 and 2 30 is placed on the driving surface 37 and projects into the welding gap 41 with a projection 44 corresponding to a thickness 43 of the welding gap 41.

The cooling device 38 rests on a contact surface 45 of the rail pieces 1, 2 and has a recess 46, the width 47 of which corresponds at least to the thickness 43 of the welding gap 41 or, as shown in particular in FIG. 5, is designed to be somewhat larger. The aim of this is to achieve a certain protrusion of the additional material which protrudes beyond the contact surface 45.

In the area of the rail foot 32, only a single continuous welding zone 24 is shown here. Thus, the contact area 34 is formed between the welding zone 23 in the region of the rail web 31 with its welding beads 27 and the welding zone 24 with the welding beads 28.

Corresponding cooling with the cooling device 38 is achieved by passing coolant through a schematically illustrated line 48 in a schematically illustrated cooling circuit 49 with a pump 50 and a heat exchanger 51 for cooling the cooling medium. A corresponding temperature profile can thereby be achieved in the base material of the rail pieces 1, 2 and in the weld beads 28, 29 adjacent to the base welding bead.

The spacer 42 used in the area of the rail head 30 prevents the welding gap 41 from being in the area due to the temperature load on the rail pieces 1, 2 in the area of the rail foot 32 of the rail head 30 reduced. At the same time, an aligned position of the running surfaces 37 of the rail sections 1 and 2 welded to one another is thereby ensured.

Since the welding zone 24 or 25 can be produced with a relatively small number of a maximum of 10 welding beads 28, 29, an intimate connection between the individual welding beads 28 and 29 on the one hand and the base material of the rail pieces 1, 2 on the other hand is possible. Above all, this creates connecting webs in the manner of a tension band between the rail pieces 1, 2, for which it is possible to find sufficient length compared to the use of electrodes for producing such a welded connection with a considerably smaller number of weld beads 26 to 29.

After the two rail feet 32 of the rail pieces 1, 2 are welded to one another, as can be seen from FIGS. 6 and 7, a cooling device 39 is arranged on one of the two sides of the rail web 31 and the welding gap 41 between the end faces 6 and 7 by arrangement several horizontal weld beads 27 closed. However, there is also the possibility of welding the welding gap 41 with vertical welding beads 27, the cooling device being able to be moved from one side wall of the rail web 31 to the other during operation, so that the rail web 31 can be completely welded through.

After this operation, while the spacer 42 was still arranged between the end faces 6, 7 of the rail sections 1, 2, this spacer 42 is removed and, in addition to the cooling device 39, a further cooling device 40 is arranged on the side of the rail head 30 opposite the cooling device 39. Then the welding gap 41 in the area of the rail head 30 is filled with 10 to 12, but a maximum of 15 welding beads 26. The cooling devices 39 and 40, like the cooling device 38, have corresponding depressions 46 in the area of the welding gap 41, so that a protrusion of the respective welding beads 26 to 29 over the surfaces of the rail sections 1, 2 can be made possible. In those areas where these supernatants over the adjacent surfaces of the rail pieces 1, 2 are disruptive, these can be subsequently removed using shearing or grinding machines.

The cooling devices 39 and 40 can be acted upon with the same cooling circuit 49 as in the cooling device 38, but it is also possible to assign a separate cooling circuit 49 to each cooling device 38 or 39 or 40.

Another advantage of this solution according to the invention is, however, that by arranging a large number of welding beads 26 to 29, the loads in the individual cross-sectional areas of the rail sections 1, 2 can be taken into account more easily by suitable selection of the additional materials and, above all, different additional materials. It is thus possible, for example, to weld the uppermost or several welding beads 26 closest to the running surface (s) 37 or the rail head flanks in the area of the rail head 30 with different, e.g. to produce harder additional materials, so that an increased resistance to wear in the area of the rail head 30, in particular the running surface 37 or the rail head flanks, can be achieved.

A particular advantage of the procedure now described for producing the welded joint 5 in connection with the welding gas mentioned at the outset is that when the plasma is created, the gas atoms are dissociated into ions and free electrons or protective gases, the charged gas particles reaching very high temperatures of e.g. 6,600 to 22,200 degrees can be heated. If such highly heated gas particles are now transferred across the arc, the charged plasma particles give off their heat in order to melt away the melting electrode 9 and to heat or preheat the base material. The subsequently cooled gas particles combine again to form the molecular structure of the original gas or gases.

It also proves to be advantageous in the manufacture of the different welding zones 22 to 25 if the different properties of the additional materials 8 in welding beads which are directly adjacent to one another 26, 27, 28, 29 of a welding zone 22, 23, 24, 25 or contact area 33, 34, 35, 36 are not too different. If such a strong difference is desired, for example the hardness of the elastic modulus, the elastic elongation, the flexural strength or other relevant material properties, it is advantageous to have these values increase linearly or exponentially over several layers in order to then reach the final value. This avoids internal stresses in the weld seam and stress cracks can also be prevented in the subsequent operating loads.

Furthermore, when manufacturing the individual welding beads 26 to 29, it must be taken into account that a uniform structure can be achieved, in particular with high strengths, if the individual welding beads 26 to 29 are applied directly in succession in the various adjacent welding zones 22 to 25. This eliminates multiple cooling and heating of the connection area with the harmful disadvantages regarding embrittlement and internal tensions. Of course, this applies not only to the production of the adjacent welding beads 26 to 29 in each welding zone 22 to 25, but also to the immediately successive production in the adjacent welding zones 22 to 25 in their contact areas 33 to 36, since this causes internal tensions between the welding zones 22 to 25 can be prevented and additional structural changes in the contact areas 33 to 36 between the individual welding zones 22 to 25 can be avoided.

It has also proven to be advantageous if the immediately adjacent, successively produced welding beads 26 to 29 are applied in a welding zone 22; 23, 24, 25 or in the adjacent welding zones 22 to 25 in opposite welding directions. This has the advantage that structural changes at the beginning of each welding process can be avoided, since this welding bead 26 to 29 is produced as an endless, theoretically zigzag-shaped welding bead 26 to 29 and thus transitional losses due to the renewed beginning of welding in Edge area of the welding zone 22 to 25, between the individual welding beads 26 to 29 can be prevented.

It can also prove to be advantageous if the weld beads 26 to 29 of one weld zone 22 to 25 or the weld beads 26 to 29 in adjacent weld connections 5, which are produced one after the other, are offset with respect to one another in the longitudinal direction of the rails, but are arranged to overlap in edge regions running perpendicular to the longitudinal direction of the rails. This layer-by-layer displacement of the welding beads 26 to 29, for example by half the division, in order to produce a type of composite construction such as in masonry made of bricks, offers more intimate interlocking of the individual welding beads 26 to 29 or the individual layers of the additional material 8, which results in overall properties this weld 5 can be significantly improved.

It is of course possible within the scope of the invention to change the arrangement of the individual elements as desired or to combine them differently in addition to the exemplary embodiments shown.

Individual features from the exemplary embodiments shown can also represent independent solutions according to the invention.

Finally, it should be noted that individual parts are disproportionately enlarged or shown schematically simplified in the drawings of the exemplary embodiment for a better understanding of the invention.

List of reference symbols

• 1 rail section
• 2 rail piece
• 3 arrow
• 4 rail track
• 5 welded joint
• 6 end face
• 7 end face
• 8 additional material
• 9 melting electrode
• 10 arcs
• 11 gas jacket
• 12 shielding gas
• 13 shielding gas
• 14 shielding gas
• 15 supply roll
• 16 welding gun
• 17 line
• 18 management
• 19 control device
• 20 voltage supply device
• 21 gas bottle
• 22 welding zone
• 23 welding zone
• 24 welding zone
• 25 welding zone
• 26 welding bead
• 27 welding bead
• 28 welding bead
• 29 welding bead
• 30 rail head
• 31 rail web
• 32 rail base
• 33 Touch area
• 34 contact area
• 35 contact area
• 36 Touch area
• 37 driving surface
• 38 cooling device
• 39 Cooling device
• 40 cooling device
• 41 welding gaps
• 42 spacer
• 43 thickness
• 44 head start
• 45 footprint
• 46 deepening
• 47 width
• 48 line
• 49 Cooling circuit
• 50 pump
• 51 heat exchanger

Claims (11)

1. Weld joint between two rails arranged one behind another along a rail track, wherein the frontal ends of the rails which face each other, are connected with several beads consisting of a filler material and arranged one above another and next to each other from the rail foot to the rail head, and which is characterized in that the weld joint (5) is composed of a separate welding zone (22, 23, 24, 25) each, which connects a rail foot (32), a rail stem (31) and a rail head (30), and in that the welding zones (22 to 25) are connected in a form-locking manner in contact areas (33 to 36) directly facing each other, and in that the welding zone (22) in the rail head (30) consists of less than 15 melted beads (26) which are arranged next to each other and preferably located one above another and approximately parallel to each other and in that the welding zone (24, 25) in the rail foot (32) consists of less than 10 melted beads (28, 29) located next to each other and approximately running parallel to each other.
2. Weld joint according to claim 1, characterized in that the filler material (8) shows more resistance or respectively hardness in a surface area immediately facing at least one running surface (37) of the rail track (4) than in the other welding zones (23 to 25).
3. Weld joint according to claim 1 or 2, characterized in that the welding zones (22 to 25) are produced with different filler materials (8).
4. Weld joint according to one or more of claims 1 to 3, characterized in that the welding zones (22 to 25) are produced in several layers and preferably, at least in individual layers produced of different filler materials (8).
5. Weld joint according to one or more of claims 1 to 4, characterized in that the hardness, the modulus of elasticity and the tensile strength of the filler materials in the welding zones or respectively the layers in direction of the running surface (37) or respectively in the direction of the rail foot (32) are linearly and/or exponentially changed.
6. Method for the production of a weld joint between the frontal ends, which face each other, of the rails of a rail track, wherein the two said frontal ends of the rails are apart from each other by the thickness of a welding gap, and, in particular, according to one or more of claims 1 to 5, characterized in that by using a shielding gas (12 to 14) of 40% to 70% argon, 25% to 60% helium, 3% to 10% carbon dioxide and 0,1% to 1% oxygen and a consumable electrode (9) having a diameter of 0,8 mm to 0,4 mm and an amperage in the range of 100 to 1 100 amperes, beads (27) are applied one above another in a welding zone (24 or respectively 25) in the region of the rail foot (32) , whereupon the beads are produced in a welding zone (23, 22) located in the area of the rail stem (31) and in a welding zone located in the area of the rail head (30), wherein the welding zones (22; 23; 24, 25) produced apart from each other are connected in a form-locking manner in contact areas (33 to 36) directly facing each other, and wherein the welding zone (24, 25) of the rail foot (32) is produced by not more than 10 beads (26) above one another and the welding zone (22) of the rail head (30) by not more than 15 beads (26) above one another.
7. Method according to claim 6, characterized in that at first a cooling device is assigned to the welding gap on the supporting surface of the rails facing away from the rail head (30), and in that the welding zone (24, 25) is filled up with filler material (8), whereupon the cooling device (38) is removed and thereafter, a cooling device (39) is assigned to the welding zone (23) in the region of the stem of the rail (31).
8. Method according to any one of claims 6 or 7, characterized in that the individual beads (26 to 29) in the particular welding zones (23 to 25) are applied each time immediately following each other.
9. Method according to one or more of claims 6 to 8, characterized in that the beads (26 to 29) in a further welding zone (22; 25; 23, 24) adjacent to a finished welding zone (23, 24) are produced prior to the cooling down of said beads (26 to 29) in the already finished welding zone (23, 24).
10. Method according to one or more of claims 6 to 9, characterized in that the immediately neighbouring and successively produced beads (26 to 29) of a welding zone (22 to 25) are applied in each of the following welding directions in the opposite direction.
11. Method according to one or more of claims 6 to 10, characterized in that the beads (26 to 29) in the corresponding welding zones (22 to 25) or respectively in the welding zones next to each other (22 to 25) are offset along the rail tracks and overlapping the bordering areas vertical of the lengthwise direction of the rails.

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