JP2837605B2 - Automatic rail welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic fusion welding technique for butt welding railroad or crane rails.

[0002]

2. Description of the Related Art Conventionally, butt welding of rails has been performed by using I
An enclosed arc welding method using a covered arc welding rod is used, in which the rail legs are multi-layer welded after butting the mold grooves, and then the rail pillars and the head are surrounded by a metal material and continuously welded. . However, since the welding method is a manual welding method, there are many parts that depend on the skill of the welding operator, so that skill is required, welding time is long, construction efficiency is not improved, and work environment such as welding fume is problematic. Therefore, a highly efficient automatic welding method that does not require skill of a welding operator has been demanded.

[0003] Against this background, various automatic welding methods have been studied in place of the enclosed arc welding method. The technique disclosed in Japanese Patent Publication No. 44-24249 is also proposed as an alternative to the welding method.
The welding of the rail foot is interrupted for each layer by the submerged arc welding method, welding is performed while removing solidified slag, and the rail column and the head are welded by the electroslag welding method. According to the technique disclosed in Japanese Patent Application Laid-Open No. 1-2779, the first layer of the rail is welded by the submerged arc welding method, and the second layer shifts to the electroslag welding method. A method of welding by an electroslag welding method has been proposed. Further, in the technique disclosed in Japanese Patent Publication No. 45-14173, a method of welding the entire cross section of a rail by a gas shield welding method has been proposed. JP-B-45-19369 and JP-B-6-19
The technique disclosed in Japanese Patent Application Laid-Open No. 1-249679 is also a method in which rails are butt-welded using a gas shielded arc welding method.

[0004]

The prior arts described above are all fusion welding methods and do not require pressing in the axial direction of the rail, and are more efficient and more efficient than the enclosed arc welding method. However, it still has many problems. That is, in the technique disclosed in Japanese Patent Publication No. 44-24249, since submerged arc welding is performed on each layer of the rail foot, solidified slag must be removed for each layer. After the end of the rail foot welding, the welding is temporarily interrupted to prepare for restarting the electroslag welding, and then the rail column and the head are welded. Therefore, welding defects such as poor penetration and solidification cracks are likely to occur at the start and stop portions of each welding, and the welding efficiency is reduced. Furthermore, the flux of the welding material is selectively used for the rail foot, the pillar and the head due to the difference in welding methods, and the characteristics of the welding power source are switched. However, problems remain in the management of welding materials.

In the technique disclosed in Japanese Patent Application Laid-Open No. 1-2779, the development of a low-melting-point, low-viscosity, molten flux has led to the development of a submerged arc welding method for the first layer of a rail foot.
This is a welding method in which the transition to the electroslag welding method after the first layer can be quickly performed, and welding of the rail head can be continuously performed from the first layer of the rail foot. However, when the rail foot is welded by the welding method, a large amount of welding is required to re-melt the solidified slag formed by the first layer submerged arc welding in the second layer of the rail foot and shift to electroslag welding. Heat input is required. On the other hand, from the viewpoint of preventing solidification cracking, the range of conditions for welding current, welding voltage, and welding speed that can be adopted is remarkably narrow due to conflicting constraints that excessive heat input must be avoided. Therefore, due to the increase in variables such as atmosphere, molten metal humidity, groove accuracy and the like in the field welding, there is no danger of minute unmelted defects remaining in the primary solidified slag.

In the method of welding the entire cross section of a rail by gas shield welding as in the technique disclosed in Japanese Patent Publication No. 45-14173, a shield gas is used from the start to the end of welding, so that the present technique is applied to on-site construction. It is extremely difficult to keep the shielding effect of the shielding gas sound by completely protecting the wind resistance from the outdoor wind to the head from the rail pillar part to the head, especially if the wind resistance is taken into consideration. In addition, even if an attempt is made to solve the problem with a jig or the like, the mechanism becomes complicated, and the construction efficiency deteriorates in terms of handling. In addition, the gas shielded arc welding method has a narrow range of appropriate welding conditions for groove dimensions, and particularly in the region from the rail column to the head where welding lamination progresses, variations in groove dimensions cause welding such as poor fusion of grooves. There is a high risk of generating defects, which poses a problem in the reliability of the welded joint.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and the gist of the present invention is to provide an automatic welding method for butt-welding rails, in which the first layer of the rail foot is formed of CO ₂ gas. Uranami welding by shield arc welding method, temporarily stop welding, reverse the traverse of the non-consumable nozzle from the welding end position, and move 50 g of molten flux while traversing the welding start side of the first layer of the rail foot / min or more, 1kg
Add into the groove at an addition rate of / min or less. Thereafter, the feeding of the welding wire is started, the second layer of the rail foot is welded by the submerged arc welding method, and the solidified slag formed by the second layer of the rail foot is continuously remelted on the third layer of the rail foot. After the transition to the electroslag welding method, after the transition, the non-consumable nozzle automatically rises by welding current detection and the width of the rail corresponds to the number of welding layers at the rail foot or the rail height position from the rail column to the rail head position Is controlled by a storage device to raise or repeat the traverse according to the rail shape, and is a welding method for welding up to the rail top surface,
In a series of welding, CO ₂ gas or flux is automatically supplied using the frame-type fixing metal placed on the top of the rail foot and the outer cylinder of the non-consumable nozzle, and molten slag or molten metal is prevented from flowing out In addition, a DC power source having a constant voltage characteristic and a welding wire diameter of φ1.2 mm to φ2.0
25 to 40% by weight of CaF ₂ and 20% by weight of SiO ₂ as a low melting point and low viscosity molten flux
35%, with TiO ₂ 5-15%, and CaF ₂ + S
CaF ₂ —SiO ₂ —T containing 50% or more of iO ₂
An automatic rail welding method is characterized in that welding is performed using a molten flux containing iO ₂ as a main component.

[0008]

The present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the method of the present invention, and FIG. 2 is a cross-sectional view of the embodiment as viewed from a rail end surface which is a member to be welded.

In FIG. 1, reference numerals 1a and 1b denote rails which are members to be welded, which are installed in a state where they are abutted with an appropriate gap between the end faces. Reference numerals 2a and 2b denote frame-type fixing abutments, which are rail top abutments 2b, respectively.
And a pair of abutments 2a surrounding the rail head side to the rail foot are connected by two pins, and the lower abutment 2a from the rail head side is opened around the rail top abutment 2b. In welding, the rails 1a and 1b are installed so as to cover the heads of the rails 1a and 1b to prevent molten metal and molten slag from flowing out during welding. Reference numerals 3a and 3b denote fixed moving gaps in the directions of arrows 10 and 11 by means of a hydraulic drive mechanism (not shown) after the welding of the rail foot is completed with a moving allowance, so that a fixed gap is formed between the rail pillar and the rail head side. To prevent the molten metal and the molten slag from flowing out by electroslag welding after the rail pillar portion. 4a and 4c are windproof walls provided with a shielding gas supply cavity, and have a box-shaped structure with an internal cavity.
In welding, it is used by placing it on the fixed abutments 2a and 2b,
Together fulfill an action as windbreak with CO ₂ gas shielded welding of the rail foot first layer, the shielding gas supply port 8a provided on the side wall, the shield gas supplied from 8b shielding gas outlet 9a, from 9b to the open destination within And introduce. 4b, 4
d is a windbreak wall used as a pair with each of 4a and 4c. Reference numerals 5a and 5b denote rail foot abutments which are fixed to one of the fixed abutments 2a and 2b with bolts or the like, respectively, to prevent molten metal from flowing out during welding. Reference numeral 6 denotes a backing material storage frame, which is used by being connected to the fixing backings 2a and 2b, and closely adheres a backing material 7 made of a cordierite-based solid material and a glass fiber sheet to the back surface of the rail foot. The backing material 7 prevents the underside bead from dropping in the first layer welding of the rail foot, keeps the bead shape sound, and smoothes the bead surface.

Reference numeral 12 denotes a welding filler wire, and reference numeral 13 denotes a non-consumable nozzle that guides the filler wire 12 into the groove of the rail and supplies electric power from the welding power source to the filler wire 12. The non-consumable nozzle 13 is covered by a consumable outer cylinder 14 attached to the branch port 15, and the molten flux 23 and / or the CO ₂ gas 24 for gas shielding are railed through the branch port 15. Filler wire tip (arc point) in the right place at the right place depending on the shape of the welded part
It has a structure that can be automatically supplied to the vicinity. Reference numeral 16 denotes a holder, which moves the non-consumable nozzle 13 to a motor 21 for lifting and lowering.
And a non-consumable nozzle 13 held by an elevating device 20 including elements such as a ball screw, a pinion, a gear, a bearing, and an outer frame.
Can be moved up and down in the arrow direction 22 of FIG. Reference numeral 17 denotes a traversing device, which comprises a traversing motor 18 and elements such as a ball screw, a pinion, a gear, a bearing, and an outer frame, and is used in conjunction with a lifting device 20 to enable traversing movement in the arrow direction 19. . Reference numeral 32 denotes a flux hopper and a feeder. By supplying a melted flux 23 which has been dried beforehand in the hopper before the start of welding, an appropriate amount of the melted flux is supplied at a position according to the output signal from the storage device during welding. 23 can be supplied into the rail groove through the above-mentioned branch port 15 and consumable outer cylinder 14. According to the above configuration, the tip of the welding filler wire 12 performs welding while drawing the axis trace of 31 in FIG. 2. However, the movable abutments 3a and 3b stop when the welding is completed on the rail foot, that is, at the tip of the welding filler wire. 3a-1, 3 after point A of the shaft trace 31
Move to b-1. The configuration according to the embodiment of the present invention has been described above.

Next, the welding method of the present invention will be described in more detail with reference to FIGS. First, the state of the rail foot first layer backside welding will be described with reference to the cross-sectional view of an example of the embodiment of the present invention shown in FIG. CO that shields the arc directly in the figure
_{The two} gases 24 are supplied through a consumable outer cylinder 14 through which the non-consumable nozzle 13 penetrates. In order to complete the effect of the shield, the CO ₂ gas 24 that replaces the atmosphere of the entire rail foot to be welded is provided on the windproof wall 4 a with the shield gas supply cavity.
Gas outlets 9a and 9b provided in the air outlets 4a and 4b
Supplied from That is, the CO ₂ gas shield arc welding of the first layer of the rail foot is performed in a double shield state in which the shield gas divided into three by the flow controller is adjusted in flow rate and supplied into the groove. As the welding progresses, the backing material 7 also partially melts the glass fiber sheet on the surface and the cordierite-based solid material, forming a thin slag film on the back surface of the formed rail foot first layer welding bead 25. Smooths the shape of the surface and edges of the overlay weld bead. The backing material 7 has cordierite having relatively high fire resistance because the margin height of the uranami bead is not excessively large even if the groove of the non-weld is I-shaped and the root interval is relatively wide, 14 mm to 22 mm. A continuous groove extending in a direction transverse to the axis of the rails 1a and 1b is provided on the surface of the solid material of the system, and a glass fiber sheet is attached and used. The best welding result was obtained by this method.

Next, the state of the addition of the molten flux 23 after the welding of the rail foot first layer backside wave will be described with reference to the cross-sectional view of one example of the embodiment of the present invention shown in FIG. In the figure, the non-consumable nozzle 13 reverse-welds the first layer of the rail foot by CO ₂ gas shielded arc welding, stops the traversing operation, and then automatically stops the welding arc and the CO ₂ gas for gas shielding. This is a state in which the molten flux 23 is added to the welding groove while the traversing direction is continuously reversed. At this time, the required amount of the molten flux 23 to be supplied into the groove varies slightly depending on the route interval composed of the rails 1a and 1b and the internal volume of the frame composed of the frame-type fixing abutments 2a and 2b. Body width from 24mm to 30
mm, in order to perform submerged arc welding in the next layer, an addition amount of at least 80 g is necessary,
Considering the transition to the electroslag welding after the third layer of the rail foot, the weight is preferably 300 g or less. If the traversing speed at the time of addition is 50 mm / min or less, it takes too much time to complete the addition, which is not preferable in terms of efficiency.
At a speed of more than 00 mm / min, the added molten flux 23 is unbalancedly sprayed toward the welding start side of the second layer in the groove, which is not preferable for welding. For the reasons mentioned above, the addition rate is 50 g
It is desirable to add in the condition range of 1 kg / min or more and 1 kg / min or less, and the traversing speed needs to be adjusted according to the addition speed so that an appropriate addition amount can be added most efficiently.

Next, the state of submerged arc welding of the second layer of the rail foot will be described with reference to the cross-sectional view of one example of the embodiment of the present invention shown in FIG. In welding, submerged arc welding is performed while partially remelting the rail foot first layer welding bead 25 with the added molten flux 23. In the figure, reference numeral 25 denotes a first-layer weld bead, 26 denotes a second-layer weld bead, and 23 denotes a molten flux.

Next, the state of electroslag welding of the third and subsequent rail foot portions will be described with reference to the sectional view of the embodiment of the present invention shown in FIG. After the welding of the second layer is completed, the non-consumable nozzle 13 is continuously welded without interrupting the welding.
Is performed by reversing the traversing direction. The figure shows the state after shifting to electroslag welding on the third layer while remelting the slag solidified during the second layer welding, after which the automatic ascent and traverse reversal are repeated, and the welding is performed on the rail foot. When the operation is completed, the moving allowances 3a and 3b are automatically brought into contact with the positions shown by the dotted lines in the figure (see FIG. 2), and the rail pillars are continuously welded. Was formed by submerged arc welding of the second layer solidified slag, due to the relatively high temperature condition by preheating effect of the rail by root pass CO ₂ gas shielded arc welding, solidified slag is easily re-melted at a third layer There is no danger of unmelted slag remaining. In the electroslag welding of the third and subsequent layers, if the traverse width is reduced in accordance with the shape of the rail as the welding progresses, the welding margin formed on the rail foot surface can be made thinner. It will be easier.

Next, the welding of the rail column and the head will be described with reference to a sectional view of an embodiment of the present invention shown in FIG. In the figure, reference numeral 13b denotes a state of the non-consumable nozzle at the time of rail column welding, and reference numeral 29 denotes a molten slag at that time. On the other hand, 13c and 13d show the state of the non-consumable nozzle during welding of the rail head, and 30 shows the molten slag at that time. Reference numerals 3a and 3b denote moving members, which are brought into contact with the positions shown in the drawing during welding of the rail pillar portion and the head portion, to prevent the molten metal and the molten slag from flowing out of the frame, and adjust the shape of the molten bead. Also, in welding, after the welding of the rail foot is completed, the moving abutments 3a and 3b are brought into contact with each other, and at the same time, the traverse of the non-consumable nozzle is stopped at the center of the rail width. And electroslag welding the rail column. Also, when the welding proceeds to a position 10 mm to 30 mm below the height position before welding enters the rail head, the addition speed is 20 g / min to 100 g / min.
It is necessary to automatically add the molten flux 23 within a range of seconds to 120 seconds. At this point, by gradually increasing the depth of the molten slag 29, the welding enters the head and the welding area suddenly expands. This prevents the slag 29 from becoming shallow and causing a visible arc. When welding enters the rail head, the non-consumable nozzle 13 restarts traversing, repeats traversing repeatedly while increasing the traversing width according to the rail shape, detects welding current and automatically ascends to a desired height position. Complete the welding.

In completing the above welding method of the present invention,
The present inventors have studied the welding power source, the diameter of the welding wire, the type of flux, and the like in the past from both aspects of welding workability and welding joint performance. First, in order to perform good Uranami welding by CO ₂ gas shielded arc welding in the first layer of the rail foot, a small-diameter welding wire may be used to secure current density. However, if the wire diameter is less than 1.2 mm, even if welding is performed at the upper limit of the appropriate current range, the spread of the arc is small and the amount of weld metal and heat input sufficient to bridge the groove cannot be obtained. On the other hand, if the welding wire diameter exceeds 2.0 mm, the current becomes excessively large to perform welding at an appropriate current density, and a large-capacity welding power source is required.

If a welding power source is a direct current power source having a constant voltage characteristic and the welding wire is fed at a constant speed to perform welding, C
It has been found that welding can be favorably performed with a small-diameter welding wire even when switching to submerged arc welding and electroslag welding as well as O ₂ gas shielded arc welding. Furthermore, the welding flux added when switching from CO ₂ gas shielded arc welding to submerged arc welding,
Once solidified, it is necessary to quickly re-melt in the next layer welding to form a molten slag bath having an appropriate depth. For this purpose, 25 to 40% by weight of CaF ₂ ,
O ₂ is 20 to 35% TiO ₂ 5-15% and Ca
CaF ₂ —Si containing 50% or more of F ₂ + SiO ₂
A low-melting-point, low-viscosity molten flux mainly composed of O ₂ —TiO ₂ is suitable. If the content of CaF ₂ is less than 25% and the content of SiO ₂ is less than 20%, the viscosity and melting point of the generated slag are high, and the transition to electroslag welding does not proceed smoothly, and the welding becomes unstable. On the other hand, if CaF ₂ exceeds 40%, a large amount of fluoride gas is generated, which impairs the working environment. Also Si
If O ₂ exceeds 35%, the viscosity of the slag becomes too low, so that the slag easily flows out and becomes unstable. However, the total of CaF ₂ + SiO ₂ needs to be 50% or more, and if it is less than 50%, it takes time to re-melt when transitioning to electroslag welding, and a solidified slag biting defect is generated inside the weld. there is a possibility.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which a rail for railroad 50 kgN rail is butt-welded with an I-shaped groove in accordance with the above-described configuration and procedure will be described. Examples of the configuration of the present invention are shown in Examples 1 to 4, and Comparative Examples 1 and 2. In Examples 1 to 4, welding without defects was successfully performed. In Comparative Example 1, the addition rate of the molten flux was out of the range of the present invention,
Since the addition was made to the side of the rail foot second layer in the groove so as to be offset toward the welding start side, in the submerged arc welding of the rail foot second layer, the welding was in a visible arc state during the progress, and the rail foot third layer was continuously formed. During the transition to electroslag welding, the solidified slag formed in the second layer of the rail foot could not be completely melted during the transition to the electroslag welding, and the welding wire was suspended on the solidified slag. In Comparative Example 2, the amount of the molten flux added was in accordance with the present invention, and the composition was excluded from the present invention and welding was performed. As a result, the welding was interrupted in the same manner as in Comparative Example 1 without completely remelting the solidified slag formed in the second layer of the rail foot portion in the third layer of the rail foot portion. The welding methods and conditions of each of the examples and comparative examples are shown below.

[Example 1] Groove shape: I-shaped groove, width 16 mm Welding wire: 1.6 mm (solid wire) Flux: molten flux CaF ₂ : 35%, TiO ₂ : 10%, CaO: 20
%, SiO ₂ : 30% Rail foot flux addition amount: 140 g (addition speed: 2
80 g / min, the fixed losses frame body 27W × 150L) Shield Gas: CO ₂ 100% (supply from depletable outer cylinder: 45l / min, supply from wind wall: 30l / min × 2) welding power supply: DC constant Voltage characteristics, rated output 500A

[Table 1]

Example 2 Groove shape: I-shaped groove, width 18 mm Welding wire: φ1.6 mm (solid wire) Flux: molten flux CaF ₂ : 35%, TiO ₂ : 7%, CaO: 25
%, SiO ₂ : 25% Rail foot flux addition amount: 140 g (addition speed: 4
20 g / min, the fixed losses frame body 27W × 150L) Shield Gas: CO ₂ 100% (supply from depletable outer cylinder: 45l / min, supply from wind wall: 30l / min × 2) welding power supply: DC constant Voltage characteristics, rated output 500A

[Table 2]

[Example 3] Groove shape: I-shaped groove, width 15 mm Welding wire: φ1.2 mm (solid wire) Flux: molten flux CaF ₂ : 40%, TiO ₂ : 12%, CaO: 18
%, SiO ₂ : 25%, MgO: 5% Rail foot flux addition amount: 120 g (addition speed: 9
60g / min, 27W × 150L inside fixed metal frame) Shielding gas: 100% CO ₂ (supply from consumable outer cylinder: 45l / min, supply from windbreak wall: 30l / min × 2) Welding power supply: DC constant Voltage characteristics, rated output 500A

[Table 3]

Example 4 Groove shape: I-shaped groove, width 16 mm Welding wire: φ2.0 mm (solid wire) Flux: molten flux CaF ₂ : 40%, TiO ₂ : 15%, CaO: 10
%, SiO ₂ : 22%, MgO: 5% Rail foot flux addition amount: 160 g (addition speed: 8
0 g / min, the fixed losses frame body 27W × 150L) Shield Gas: CO ₂ 100% (supply from depletable outer cylinder: 45l / min, supply from wind wall: 30l / min × 2) welding power supply: DC constant Voltage characteristics, rated output 500A

[Table 4]

Comparative Example 1 Groove shape: I-shaped groove, width 18 mm Welding wire: φ1.6 mm (solid wire) Flux: molten flux CaF ₂ : 34%, TiO ₂ : 8%, CaO: 24
%, SiO ₂ : 30% Rail foot flux addition amount: 350 g (addition speed: 1
200 g / min, the fixed losses frame body 27W × 150L) Shield Gas: CO ₂ 100% (supply from depletable outer cylinder: 45l / min, supply from wind wall: 30l / min × 2) welding power supply: DC constant Voltage characteristics, rated output 500A

[Table 5]

Comparative Example 2 Groove shape: I-shaped groove, width 16 mm Welding wire: φ1.6 mm (solid wire) Flux: molten flux CaF ₂ : 15%, TiO ₂ : 25%, CaO: 10
%, SiO ₂ : 15%, Al ₂ O ₃ : 30% Rail foot flux addition amount: 140 g (27 W × 150 L in fixed metal frame) Shielding gas: CO ₂ 100% (supply from consumable outer cylinder: 45 l) / min, supply from windbreak wall: 30 l / min x 2) Welding power supply: DC constant voltage characteristics, rated output 500A

[Table 6]

As a result of welding in the above manner, Examples 1-4
The welding is started in 15 min to 18 min after the welding start switch is turned on except for the setup before welding and the processing after welding, and there is no defect of the welded joint in a later investigation, and the mechanical test performance is sufficient. It was confirmed that.

[0026]

As described above, according to the present invention, in the field welding of the rail, the automatic welding from the foot of the rail to the head of the rail is performed by the CO ₂ gas shielded arc welding method, the submerged arc welding method, and the electroslag welding method. It can be performed efficiently in combination.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view as viewed from the end face of the rail.

FIG. 3 is a sectional view of a rail foot first layer being welded according to the present invention.

FIG. 4 is a cross-sectional view showing that a molten flux for performing a folded second layer submerged arc welding is being sprayed after the rail foot first layer welding.

FIG. 5 is a cross-sectional view during welding of the rail foot second layer.

FIG. 6 is a sectional view of the third and subsequent rails during welding;

FIG. 7 is a cross-sectional view during welding of a rail column and a head.

[Explanation of symbols]

1a, 1b Rail 2a, 2b Fixing allowance 3a, 3b Moving allowance 4a, 4c Windproof wall with shield gas supply cavity 4b, 4d Windproof wall 5a, 5b Rail foot allowance 6 Backing material storage frame 7 Backing material 8a, 8b Shield gas supply port 9a, 9b Shield gas blowout port 10, 11 Moving fund moving direction 12 Weld filler wire 13 Non-consumable nozzle 14 Consumable outer cylinder 15 Branch port 16 Holder 17 Traversing device 18 Traversing motor 19 Traverse movement direction 20 lifting device 21 lifting motor 22 lifting movement direction 23 melt flux 24 gas CO ₂ shielding gas 25 root pass weld bead 26 2-layer welding bead 27 3 and subsequent layers weld bead 28, 29, 30 molten slag 31 welded Trajectory of filler wire tip 32 Flux hopper and feeder

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Okumura 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Kenichi Kamine 20-1 Shintomi, Futtsu-shi, Chiba New Nippon Steel Corporation (72) Kazuo Sugino, Inventor 1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Yawata Works (72) Koichi Uchino, Kitakyushu, Fukuoka No. 1-1 Tobata-cho, Tobata-ku Nippon Steel Corporation Yawata Works (56) References JP-A-3-297558 (JP, A) JP-A 64-2779 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) B23K 9 / 038,9 / 18,25 / 00

Claims (1)

(57) [Claims] In an automatic welding method for butt-welding rails, an initial layer of a rail foot is backwashed by a CO ₂ gas shielded arc welding method, welding is temporarily stopped, and a non-consumable nozzle is provided from a welding end position. Of the molten flux while traversing the welding start side of the first layer of the rail foot
Add to the groove at an addition rate of 0 g / min or more and 1 kg / min or less, then start feeding the welding wire, weld the second layer of the rail foot by the submerged arc welding method, and continuously In the third layer of the part, the solidified slag formed in the second layer of the rail foot part is re-melted and the method shifts to the electro slag welding method. After the transition, the non-consumable nozzle is automatically raised by detecting the welding current and welding at the rail foot part By controlling the traversing width corresponding to the number of layers or the rail height position at the rail head from the rail column part to the rail shape, it is raised or repeatedly traversed according to the rail shape, and the welding method to weld to the rail top surface There, in a series of welding, using a frame type fixed charges and the outer tube of non-consumable nozzles placed on the rail foot upper face, performs automatic supply of CO ₂ gas or flux, molten Suraguma Prevents the outflow of molten metal further welding wire diameter and a DC power supply having a constant voltage characteristic .phi.1.
As a low-melting and low-viscosity molten flux having a low melting point of 2 mm to 2.0 mm, the content of CaF ₂ is 25 to 40% by weight of the flux.
%, SiO ₂ is 20~35%, TiO ₂ is 5% to 15%
C containing 50% or more of CaF ₂ + SiO ₂
An automatic welding method for rails, characterized in that welding is performed using a molten flux containing aF ₂ —SiO ₂ —TiO ₂ as a main component.