JP3256113B2 - Backing material for automatic rail welding and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backing material for one-side welding of a rail base portion by a gas shield arc welding method when a rail is automatically welded on site.

[0002]

2. Description of the Related Art As a backing material which has been conventionally used when a rail base portion is constructed by a single-sided gas shield arc welding method, a composite backing material described in Japanese Patent Publication No. 45-19369 is used. is there. This backing material is more than 40% Fe
Containing 35 to 85% of metal powder containing
₂ , CaCO ₃ , MgCO ₃ , TiO ₂ , MnO, Si
An upper layer having a bulk specific gravity of 1 to 7.5, containing 65 to 15% of a slag agent containing 30% or more of an oxide or carbonate having a melting point of 2000 ° C. or less such as O ₂ , 1 such as SiO ₂ , MgO, ZrO ₂ , Al ₂ O ₃
40% of oxides having a melting point of 700 ° C. or more as a whole
A backing material comprising the lower layer containing the above and molded into a plate shape and having a bulk specific gravity of 1.5 or more.

Japanese Patent Application Laid-Open No. 6-304760 discloses a backing material comprising a cordierite-based solid material and a glass fiber sheet, which has irregularities continuous on a surface of the backing material in a direction perpendicular to a welding line. The description is shown. In addition to the rails, the backing material in one-sided reverse surf welding is the actual flat 1-89.
Japanese Patent Application No. 888 and Japanese Patent Application No. 6-089176 (Japanese Patent Application Laid-Open No. 7-276095) describe a backing material having a groove parallel to a welding line on the surface of the backing material.

[0004]

In a case where rails for railroads or cranes are butted on site and continuous welding is performed from a rail base portion to a rail top portion by automatic welding, the outer diameter of a welding device, especially a welding torch. , The welding groove must be wide (12 mm to 20 mm). Therefore, in terms of welding conditions, if the rail and groove to be welded are bridged in one pass by welding the first layer of the rail base to obtain a good back bead, the weld metal equivalent to the groove and a large current It is desirable that the backing material has a high refractory property that can withstand the large current. Furthermore, in order to prevent the formation of welding defects such as dents formed on the back bead surface or blow holes in the weld metal due to trapping of gas generated during welding when forming the first layer bead, study the composition of the solidified flux and actively A shape that allows the generated gas to flow out is required.

[0005] However, the aforementioned Japanese Patent Publication No. 45-1936.
In the technology disclosed in Japanese Patent Application Publication No. 9-90, the composition and the bulk specific gravity of the solidification-forming flux are examined, and the effect of preventing dripping of the back bead by using two sheets each having a different melting point is used to some extent. Although you can get
No measures have been considered to control the gas generated during welding and the shape of the back bead toe end. For this reason, there is a possibility that dents and the like formed on the surface of the back bead may occur, and there is a problem that the solidification-forming flux melted during welding becomes solidified slag and is caught in the end of the toe.

[0006] In addition, Japanese Patent Laid-Open Publication No.
No. 304760, this technique uses SiO ₂ —Al
A backing material that has improved fire resistance with a ₂ O ₃ -MgO-based composition. Gas generated during welding is externally provided by providing irregularities that are continuous in the direction perpendicular to the welding line on the contact surface with the material to be welded. It is a technique that can obtain a good back bead to some extent because it can be poured out. However, even in this technique, at the end of the first layer welding of the rail base portion, the back bead slightly drips from the welding start side, and the toe end shape of the front bead on the surface of the rail base portion may deteriorate.

[0007] Further, not only the rail backing material but also other backing materials for single-sided welding have been studied. However, none of the technologies can cope with a wide groove as in this technical field. At the end of welding, there is a drop in the back bead, and gas marks may also be generated on the back bead appearance.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a groove on a rail, butted against the rail.
In the backing material for rail automatic welding used for downward single-side welding, a side that abuts against the back surface of the foot as a member to be welded is symmetrical about the welding line and is 15 ° to 15 ° from the center line.
A backing material for rail automatic welding, characterized in that the backing material has irregularities with an angle of 60 ° and a depth of 2 mm to 5 mm, and the concave portion of the irregularities is a solidification-forming flux continuous in a direction crossing a welding line. It is. Here, a glass fiber sheet with a mark indicating the groove center is mounted on the surface of the solidification-forming flux on the side that comes into contact with the rail, and the solidification formation with a length in the welding line direction of 30 mm to 50 mm. The flux is temporarily fixed with a nonflammable pressure-sensitive adhesive tape continuously from the back surface where the unevenness of the solidification-forming flux is not provided, and the solidification-forming flux composition is
Al ₂ O ₃ : 45% by weight based on the total weight of the flux
_{~65%, SiO 2: 20~50%} , ZrO 2: 3~8
%, MgO: 1 to 7% and Al ₂ O ₃ , Si
It is also characterized in that the total of O ₂ and ZrO ₂ is 90% or more, and the apparent porosity of the solidified flux is 20 to 40%.

[0009] In using the backing material for automatic rail welding, the unevenness of the solidification-forming flux abuts in the direction in which the welding progresses, and welding starts when the first layer of the rail base is welded. The solidification flux that comes into contact with the center of the rail cross-section on the side to be used has a component range of 45 to 55% of Al ₂ O ₃ , and is used from the center of the rail cross-section to the end of the first layer welding of the rail base. contacts the solidified forming flux 55 is component range of Al ₂ O ₃
A method of using a backing material for rail automatic welding, characterized in that 65% of the material is used.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. The backing material of the present invention is a solidified flux backing material having the shape shown in FIG. 1, wherein (a) is a plan view, (b) is a front view, and (c) is a side view. Numeral 5 shown in the solidified flux backing material 1 shown in FIG. 1 is an unevenness provided on a surface that comes into contact with the groove back surface of the rail to be welded. Symmetrically, the angle θ is 1
It is formed at 5 ° to 60 °, and the recesses are continuous in the direction crossing the welding line, so that the gas passage is good. The depth D is 2 in the height direction of the solidified flux backing material 1.
mm to 5 mm.

The reason why the irregularities are formed in the above-described shape and arrangement is that gas components generated during welding are positively discharged to the outside of the welding groove, and are appropriately melted by arc heat during welding and secondary melting by the molten metal. This is to improve the welding defects such as pits and blowholes which are likely to occur in the weld metal by making the back bead uniform and making the back bead shape uniform. Unevenness 5
If the angle θ is less than 15 °, the gas component generated during welding wraps around the front of the welding groove, and pits are likely to be generated in the weld metal during welding, which is not preferable. When the angle θ of the unevenness 5 exceeds 60 ° and approaches 90 °, the gas component generated during welding becomes difficult to be discharged, and flows into the molten metal side immediately after welding to generate gas marks on the back bead appearance. Is not preferred.

[0012] In the present invention, the reason for forming the above-mentioned irregularities without providing grooves or slag pockets parallel to the welding line on the surface of the solidified flux backing material as in the prior art is that the slag in the prior art is used. Pockets and grooves may have a good bead shape when welding with small heat input with a constant groove width or a small gap width with a small groove width,
This is because if the mounting position of the backing material is shifted, the back bead may be shifted, and sometimes welding defects such as undercut and overlap may occur. Further, since the present invention is an automatic welding in the field, it is difficult to obtain a groove with high precision as described above, and the welding using the auxiliary filler material shown in FIG. The backing material provided with the pocket is not preferable because the auxiliary filler material falls into the slag pocket, the wire protrusion length becomes unstable, and the weld bead becomes uneven.

Further, the reason why the unevenness 5 is opened in the welding direction in use is that the generated gas is positively discharged out of the groove by the arc force and the inflow of the molten metal. Further focusing on the fact that the solidification of the weld metal, which is solidified with the progress of welding, occurs continuously on the welding start side,
This is due to the fact that a new finding of stabilizing the solidification of the molten metal and making the back bead shape uniform has been obtained.

The reason why the depth D of the unevenness 5 is limited to 2 mm to 5 mm is that if the depth of the unevenness 5 is less than 2 mm, the solidified flux backing material 1 is welded in the same manner as in the prior art in which the unevenness 5 is not provided on the surface. The effect of discharging the generated gas to the outside of the groove is impaired, and the convection of the molten metal during welding is not sufficiently performed to cause poor penetration, which is not preferable. On the other hand, if the depth of the unevenness 5 exceeds 5 mm, the back bead after welding becomes excessively large, which is not preferable.

Further, in the present invention, as shown in FIG. 2, the glass fiber sheet 2 is attached to the surface of the solidified flux backing material on which the unevenness 5 is provided, and is temporarily fixed with a nonflammable adhesive tape 3 from the surface without the unevenness 5. It is preferable to configure. 3 and 4 are a plan view and a side view, respectively, showing a use state. In the figures, 4a and 4b are rails, 9 is a welding torch, 10 is an auxiliary filler material, 11 is a cut wire, and 12 is a rail toe. Copper abutment 13 is a copper abutment surrounding the periphery of the weld. The reason why the glass fiber sheet 2 is mounted on the surface of the solidified flux backing material 1 is to improve the adhesion between the backing material and the back surface of the groove formed by the rails 4a and 4b. In addition, since the mark 6 is located at the center of the solidified flux backing material 1, the backing material comes into contact with the center of the groove during mounting so that the solidified flux 1
In addition, it is possible to reduce the raw material cost and the processing cost, and to further reduce the size and weight without having an extra width. The mark 6 may be drawn directly on the glass fiber sheet 2 with a felt-tip pen or the like, or a form in which a small-diameter core wire is attached to the center of the glass fiber sheet 2 may be used.

The solidified flux backing material 1 is subdivided from 30 mm to 50 mm in length L in the direction of the welding line, and the non-combustible adhesive tape 3 is removed from the back surface of the solidified flux backing material 1.
It is preferable to stick continuously. This is because in the automatic welding of rails constructed on site, when the groove is adjusted at the rail head gauge corner by welding used rails and new rails, the bases of the rails 4a and 4b have a perfect cross-section butting. This is because it may be twisted. In this case, the solidified flux backing material 1 is 3
By subdividing the length L from 0 mm to 50 mm and temporarily fixing it with the nonflammable adhesive tape 3 continuously, a continuous and sufficient adhesion to the back surface of the groove can be obtained. At this time, if the solidified flux backing material is less than 30 mm, the number of connecting portions increases and the danger of molten metal flowing out increases, which is not preferable. If it exceeds 50 mm, it is difficult to cope with torsion of the rail base portion, and the backing material becomes difficult. This is not preferable because there is a possibility that a gap is formed between the rail and the back surface of the rail, and the molten metal may flow out.

The first half of the backing material on the welding start side is Al ₂ O ₃
Rail components using what 45% to 55%, the second half terminating the Al ₂ O ₃ is to use a 55% to 65% is a welding start position for rail shape is irregular type steel At the foot of the base part, it is a thin plate that is hardly affected by the heat input, under the rail web it is a thick plate that is affected by the heat input from the start of welding, and at the weld end, it is from the start of welding. In a thin plate affected by the heat input. Therefore, the balance between the heat input and the plate thickness proceeds almost satisfactorily from the welding start position to the bottom of the web. Therefore, by adjusting the Al ₂ O ₃ component of the solidified flux backing material in contact with the first half and the second half of welding to the above ranges, the fire resistance of the backing material in the second half of welding is improved, and the uniformity of the back bead is improved. As a result, the welding conditions can be prevented from becoming complicated.

The reasons for limiting the composition and apparent porosity of the solidified flux backing material in the present invention are described below. First, Al ₂ O ₃ is effective in increasing the melting point of the solidified flux backing material 1, and is an important component for adjusting the shape of the back bead when performing automatic welding of a wide I groove by gas shielded arc welding. is there. Therefore, Al ₂ O
₃ must be contained in an amount of 45% or more, and if it is less than ₃ %, the back bead lacks holding power and the back bead becomes excessively large.
If Al ₂ O ₃ is contained in an amount exceeding 65%, the solidified flux backing material has too high fire resistance, does not melt appropriately with the progress of welding, and the back bead cannot bridge the groove. Poor groove penetration occurs.

SiO ₂ also increases the viscosity of the produced slag,
It is an important component in forming a back bead. If SiO ₂ is less than 20%, the slag generated during welding lacks fluidity, and if it exceeds 50%, the slag fluidity becomes excessive, resulting in excessive slag fluidity. The slag is solidified in front of the molten metal, and it is easy to cause groove penetration failure.

ZrO ₂ , like SiO ₂ , has the effect of increasing the viscosity of the produced slag, and particularly improves the familiarity of the end of the back bead toe. For this reason, it is necessary to contain ZrO ₂ in an amount of 3% or more, and if it exceeds 8%, the viscosity becomes excessive and the back bead width becomes uneven, which is not preferable.

Further, MgO has an effect as a fire resistance adjusting component, and improves slag removability after welding, that is, smoothly improves the back bead surface without unevenness. Therefore, it is necessary to contain MgO at 1% or more. On the other hand, if the content exceeds 7%, the fire resistance becomes excessive and welding defects such as slag entrainment may occur, which is not preferable.

Other impurities include trace amounts of oxides contained in minerals, alkali oxides such as Na ₂ O and K ₂ O, and water such as adhesion water, moisture absorption water and crystallization water. Gasification occurs during the welding reaction to generate welding defects such as pits. However, it is necessary to increase the sinterability by intervening between the powder particles forming the refractory, and it is desirable that the content is adjusted to 0.1% or less. Even if these impurities are contained, Al ₂ O ₃ , SiO ₂ , ZrO ₂
Is 90% or more and within the above range, the action of holding the back bead can be enhanced, and a good back bead can be obtained.

As a method of manufacturing a solidified flux backing material, the above main component is mixed with a target component, then solidified with a mold under appropriate pressure, and sintered in a firing furnace. Pores are formed as traces of generated gas during firing. It is conventionally known that the porosity affects the fire resistance, moisture absorption, and the like of the solidified flux. For this reason, it is necessary to limit the apparent porosity to 20% to 40% in order to prevent moisture absorption during storage and to avoid excessive formation of the back bead. The apparent porosity here is a value calculated by the following equation.

Apparent porosity = (W3-W1) / (W3-W2) × 100 (%) where, W1: dry weight of solidified flux (g) W2: weight of saturated solidified flux in water (G) W3: Atmospheric weight (g) of the solidified flux that has been saturated, provided that the dry weight of the solidified flux backing material is kept in a furnace at 105 ° C. for 2 hours or more.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, according to the present invention, not only the composition of the solidified flux backing material, but also a new knowledge has been obtained not only in the shape of the backing material, but also in the technical field of obtaining a good back bead in the technical field. However, the present invention will be described in more detail with reference to the following examples. Table 3 shows Examples and Comparative Examples of the present invention in which JIS standard 50 kgN rails were welded in the forms shown in FIGS. 3 and 4. Tables 1 and 2 show welding conditions other than the backing material in Examples and Comparative Examples. The diameter of the welding wire shown in Table 1 was 1.6 mm.
It is.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

No. 3 in Table 3 Examples 1 to 6 are examples within the scope of the present invention. No. In Nos. 1 to 3, Al ₂ O within the composition range of the present invention
_{As a result} of increasing the ratio of _{3 to} the total weight and producing three levels of irregularities on the surface of the solidified flux, welding was performed. As a result, a good bead having a uniform back bead width was obtained.

No. 4, no. No. 5 is the result of welding the solidified flux backing material within the composition range of the present invention, and two levels of unevenness of the surface of the solidified flux backing material within the range of the present invention. No. In No. 4, although the depth of the uneven shape was the upper limit of the range of the present invention, and the height of the back bead formed after welding was as high as 6.7 mm,
There was no excess in the latter half of the welding, and the bead width was almost uniform, and the bead shape was judged to be good. No. In No. 5, the concave and convex shape was the lower limit of the range of the present invention, and the width of the back bead formed after welding was as narrow as 17.3 mm on average, but there was no defect such as poor penetration, so it was judged that good bead formation was made. .

In addition, No. No. 6 shows that the composition range of the solidified flux backing material is within the composition range of the present invention, and that the ratio of Al ₂ O _{3 to} the total weight is two levels, and the first half of the rail base portion first layer welding is the first half of the welding start side (S in the table). ), A solidified flux backing material in which the proportion of Al ₂ O _{3 in} the total weight was set lower was used, and in the latter half (C in the table), the proportion of Al ₂ O _{3 in} the total weight was set higher. A backing material was manufactured using a solidified flux backing material and welded. Also in this example, the back bead after welding had a good and uniform bead shape in both width and height. In particular, the back bead width immediately after the welding is started and the welding torch starts traversing and the welding enters the groove of the material to be welded tends to be narrow. Has been improved.

No. 7 to No. 7 14 is the result of a comparative example where welding was performed with a solidified flux backing material composition and shape outside the scope of the present invention. No. 7 to No. 7 No. 11 was manufactured by deviating the composition range from the range of the present invention in the shape and porosity of the present invention. No. In No. 7, MgO was more than the composition range of the present invention, and the toe end of the back bead was poorly adapted. Also N
o. In No. 8, the composition range of ZrO ₂ is larger than the composition range of the present invention, and the conformity of the end of the back bead toe is poor. No. 9 is S
The amount of iO ₂ was large and the amount of Al ₂ O ₃ was small, and the back bead became excessively large.

No. In No. 10, Al ₂ O ₃ was larger than the composition range of the present invention, the back bead was insufficient, and there was a partial groove penetration defect. No. 11 is Al ₂ O ₃ and S
When the ratio of iO ₂ and ZrO _{2 to} the total weight was less than 90%, the back bead fell in the latter half of welding, a partial bead jump occurred, and the bead excess became excessive.

No. Reference numeral 12 is a comparative example in which the porosity was set higher than the present invention in the composition range and shape of the present invention. Also in this comparative example, the back bead fell immediately after the start of welding, and the back bead became excessive, and a portion where the groove was not bridged partially occurred.

No. 13 and No. 14 is a comparative example in which the angle and the depth of the irregularities are out of the range of the present invention in the composition range of the present invention. No. Reference numeral 13 denotes a solidified flux backing material in which the angle of concavo-convex is smaller than that of the present invention and the depth of concavity and convexity is lower. The back bead was insufficiently filled, and gas marks were observed on the bead surface. No. Reference numeral 14 denotes a solidified flux backing material in which the angle of the concavities and convexities is wider than that of the present invention and the depth of the concavities and convexities is larger. The back bead had an excessively large excess, and gas marks were observed on the bead surface.

[0036]

By performing automatic welding of rails using the backing material of the present invention, the gas generated during welding is discharged well, and the dent of the back bead appearance is improved. Also, the back bead width is made almost uniform from the convection of the molten metal during welding and the stabilization of the solidification of the molten metal due to the configuration of the irregularities provided in the solidification forming flux, and the curvature of the end of the bead toe is higher than that of the conventional backing material Can be improved. Further, the extra height of the back bead can be almost uniformly improved from the welding start side to the end side by the effect of studying the composition and shape of the solidification forming flux.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a solidification-forming flux of the present invention;
(A) is a plan view, (b) is a front view, and (c) is a side view.

FIG. 2 is a side view showing an example of the backing material of the present invention.

FIG. 3 is a plan view showing an example of an embodiment of the present invention.

FIG. 4 is a side view showing an example of an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 solidification formed flux backing material 2 glass fiber sheet 3 non-combustible adhesive tape 4 a, 4 b rail 5 unevenness 6 mark indicating groove center 9 welding torch 10 auxiliary filler material 11 cut wire 12 copper toe on rail toe 13 welding Copper around the part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B23K 35/362 B23K 35/362 G // B23K 101: 26 101: 26 (72) Inventor Kenichi Kamine 20 Shintomi, Futtsu-shi, Chiba -1 Nippon Steel Corporation Technology Development Division (56) References JP-A-60-82298 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 37/06 B23K 9/038 B23K 9/16

Claims (6)

(57) [Claims] 1. A backing material for automatic welding of rails, which is used for downward facing single-side welding with a groove in contact with a rail, wherein a welding line is centered on a side which comes into contact with the back surface of a foot as a member to be welded. Symmetrical with respect to the center line, 15 ゜ -60
A backing material for rail automatic welding, characterized in that the backing material has irregularities having a depth of 2 mm to 5 mm, spread at an angle of ゜, and a solidification-forming flux in which the concave portions of the irregularities are continuous in a direction crossing a welding line. 2. A backing material for rail automatic welding according to claim 1, wherein a glass fiber sheet with a mark indicating a groove center is mounted on the surface of the solidified flux on the side in contact with the rail. 3. The length in a welding line direction is 30 mm to 50 mm.
The solidified flux formed into finely divided pieces is temporarily fixed with a non-combustible adhesive tape from the back surface of the solidified flux that is not provided with irregularities. Backing material for automatic rail welding. 4. The solidification-forming flux composition is expressed in terms of% by weight based on the total weight of the flux: Al ₂ O ₃ : 45 to 65% SiO ₂ : 20 to 50% ZrO ₂ : 3 to 8% MgO: 1 to 7% The total porosity of Al ₂ O ₃ , SiO ₂ and ZrO ₂ is 90% or more, and the apparent porosity of the solidified flux is 20 to 40%.
4. The backing material for automatic rail welding according to any one of claims 3 to 3. 5. The use of the backing material for automatic rail welding according to any one of claims 1 to 4, wherein the unevenness of the solidification-forming flux abuts in a direction that opens in the welding progress direction. How to use the backing material for automatic rail welding. 6. A center position of a rail cross section on a side where welding is started when a rail base portion first layer is welded in using the backing material for automatic rail welding according to any one of claims 1 to 4. The solidification-forming flux that comes into contact with Al ₂
Component range of O ₃ is used those of 45% to 55%, solidified form flux abutting on the rail cross-section central position to the end portion of the rail base portion first layer welding component range of Al ₂ O ₃ is 55 to 65 A method of using a backing material for rail automatic welding, wherein a backing material for rail automatic welding is used.