JP2002001557A - Butt welding method by laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a working efficiency by reducing a number of welding processes and to realize a butt welding method capable of forming a stable excess weld metal. SOLUTION: A Y type opening part of a base material 8 is formed so that a width of a V type part bottom 13 and a straight zone 14 is welded by a laser beam from the opening end of V type part. Then, the V type part is welded. The back side of the base metal 8 is not recessed by the welding of the straight zone 14. Thus, the welding process to form the excess weld metal at the back side of the base metal by an arc heat reservoir or a laser beam is not required, and the welding process will be the first process of welding the straight zone 14 and the second process of welding the V type part. Therefore, the butt welding method can be improved by reducing the number of welding processes and can be realized by the laser beam capable of forming a stable excess weld metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser butt welding method.

[0002]

2. Description of the Related Art In laser welding, approximately 1 mm of penetration is obtained per 1 kW of power, and high power density is obtained.
Evaporation occurs on the surface of the material irradiated with the laser.

For this reason, as shown in FIG.
In addition to the molten metal 7, a narrow and deep penetration called a keyhole 6 can be obtained in the molten pool by the evaporation reaction force from the surface of the base material 8 irradiated with.

Further, laser welding is a welding method characterized by high speed and low distortion as compared with arc welding.

[0005] The above-mentioned laser welding is widely used for thin plates having a thickness of about several mm, and is desired to be applied to thick plates exceeding 10 mm.

However, a laser beam machine of 10 kW class or less widely used in the general public has a limit of penetration depth of 10 mm, and a laser beam machine of 20 kW class with high output is very expensive.

[0007] Even if a laser processing machine of 20 kW is used, melting to a penetration depth of about 20 mm is the limit, and there is a limit to the melting depth for melting with a laser alone.

In order to obtain a penetration exceeding the limit by the laser alone, Japanese Patent Application Laid-Open No. 7-32338 discloses a conventional technique.
No. 6 is disclosed.

In other words, according to the technique described in this publication, a Y groove is provided at the time of butt welding, and the Y-shaped butt portion can be divided into a V-shaped portion and an I-shaped portion, that is, a straight portion. After welding the straight part with laser,
In this method, the remaining V-shaped groove is filled with a combination of laser and filler welding or arc welding.

[0010]

However, FIG.
As shown in FIG. 21, when the groove shape is Y-shaped and the V-shaped portion above the straight portion is an acute angle, when the laser is irradiated downward from above the groove when completely welding the straight portion, FIG. As shown in (1), a dent is formed on the laser irradiation surface, and a back fold (surplus or convex portion) is not formed on the back side of the base material 8, and the dent 4 is generated.

On the other hand, in the butt welding of flat plates having the same length of the straight portion, there is no V-shaped portion, a margin is formed on the laser-irradiated surface, and a rim is formed on the back side.

The difference between the groove shapes of these two materials is that a V-shaped groove is provided above the straight portion at the Y groove. Butt welding when the groove shape is Y groove,
The difference in penetration shape between the butt welding of a flat plate with only a straight portion is considered to be the effect of the V-shaped groove above the straight portion, and the phenomenon is considered as follows when the angle of the V-shaped portion is an acute angle. be able to.

That is, as shown in FIG. 19, when the width 11 of the groove with respect to the molten metal is narrow, the laser is irradiated from the groove side (V-shaped part side) to be heated and melted by the laser to be melted. Metal invades the straight portion in the narrow groove.

In this case, since a thin tube is inserted into the liquid, the capillary phenomenon as shown in FIG. A phenomenon in which the liquid in the tube rises and falls in the tube due to the adhesive force between them) causes the molten metal to rise from the straight portion to the groove side.

Here, if the surface tension is T, the diameter of the pipe is d, the contact angle of the liquid with the wall is θ, the density of the liquid is ρ, and the average height of the water surface is h, the following relational expression (1) Holds. h = (4Tcos θ) / (ρgd) (1) From the above equation (1), the height h of the liquid surface is inversely proportional to the diameter d of the tube, and when the width 11 of the molten surface in FIG. , The value of the tube diameter d can be considered small.

As a result, the average height h of the water surface increases,
As shown in FIG. 21, the surface tension T acts on the molten metal in the direction of arrow 2 and acts upward along the groove surface, so that the entire molten metal melted by the laser is moved along the groove surface. Raised upward.

Therefore, as shown in FIG. 21, a depression 4 is formed on the surface of the base material opposite to the surface on the laser irradiation side, and a stable back wave (surplus) is formed on the back side of the base material. Formation becomes difficult.

Therefore, in order to remove the poor welding which is the depression 4 generated on the back surface of the base material, Japanese Patent Application Laid-Open No. 59-2326 has been proposed.
As described in Japanese Patent Publication No. 90, it was necessary to prepare a bead from the side opposite to the laser irradiation side with an arc heat source.

Japanese Patent Application Laid-Open No. 6-114587 discloses a method of irradiating a laser 5 from the back side of a base material 8 to form a margin as shown in FIG.

However, according to the techniques described in these publications, after welding the straight portion from the groove side with a laser, and then forming an extra layer on the back surface of the base material with an arc heat source or a laser, The mold portion had to be welded with a laser or the like, and three steps were required for the welding operation.

Therefore, in the prior art of butt welding using a laser, the number of welding steps is large, and procedures such as reversal and alignment of a work (base material) are troublesome, which hinders improvement of welding work efficiency. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the number of welding steps to improve work efficiency and to form a laser capable of forming a stable margin. Is to realize a butt welding method.

[0023]

In order to achieve the above object, the present invention is configured as follows.

(1) A butt welding of a groove shape having both an opening and a straight portion. In a butt welding method using a laser for welding the straight portion with a laser, the width of the bottom surface of the groove is reduced by the laser. When welding is performed, the size of the straight portion should be equal to or larger than a size that does not cause capillary action.

(2) A butt welding in the form of a groove having both an opening and a straight part. In a butt welding method using a laser for welding the straight part with a laser, the groove is used for welding a straight part with a laser. In addition, the straight portion is formed from a wall surface having a radius of curvature that does not cause a capillary phenomenon.

If the width of the bottom portion of the groove is set to be equal to or larger than the dimension where the straight portion does not cause the capillary phenomenon, a laser beam is irradiated from the groove side, and the straight portion is welded. No depression occurs on the surface opposite to the groove surface.

For this reason, after welding the straight portion from the groove side with a laser, there is no need for a step of forming an extra layer on the back surface with an arc heat source or a laser. There are two steps, that is, a step of welding the front part, and the welding step can be simplified.

Therefore, it is possible to improve the working efficiency by reducing the number of welding steps, and to realize a butt welding method using a laser capable of forming a stable margin.

(3) A groove-shaped butt welding having both an opening and a straight portion, and in a butt welding method using a laser for welding the straight portion with a laser, Irradiates laser from the opposite side, welds the straight part, and performs joint welding of laser and gas shield arc or filler welding by combination of laser and filler wire from the surface where the opening is formed Fill the inside of the groove with welding.

By irradiating the straight portion with a laser from the surface opposite to the surface on which the opening is formed, the molten metal melted by the laser is subjected to gravity in the downward direction, and the molten metal is turned into a liquid. The metal is pulled down.

Then, the molten metal melts down on the laser irradiation surface and solidifies instantaneously, so that a margin is formed on the laser irradiation side.

Therefore, there is no need for a step of forming a margin on the back surface with an arc heat source or a laser, and the welding step includes two steps of welding a straight portion and welding a groove.

Therefore, it is possible to improve the working efficiency by reducing the number of welding steps, and to realize a butt welding method using a laser capable of forming a stable margin.

(4) A butt welding of a groove shape having both an opening portion and a straight portion. In a butt welding method using a laser for welding the straight portion with a laser, the length dimension of the straight portion is determined by using the laser alone. More than 1 times the length that can be welded and less than 2 times, and irradiate laser from the side of the butted surface where the opening is formed,
The straight portion is partially welded, and a laser is irradiated from the surface opposite to the surface on which the opening is formed, and the straight portion is welded, and the laser and the gas shield arc are irradiated from the surface on which the opening is formed. And filler welding using laser and filler wire is performed, and the inside of the groove is filled with welding.

(5) A butt welding of a groove shape having both an opening portion and a straight portion. In a butt welding method using a laser for welding the straight portion with a laser, the length dimension of the straight portion is determined by using the laser alone. More than one time and less than two times the length that can be welded, the straight part is partially welded by irradiating a laser from the surface of the butted surface opposite to the surface where the opening is formed. Laser is irradiated from the surface where the part is formed, the straight part is welded, and the welding with the laser and gas shield arc or the filler welding with the laser and the filler wire is performed from the surface where the opening is formed. Fill the inside of the groove with welding.

In the butt welding of a thick plate material, a plate material having a thickness greater than or equal to a thickness which can be welded only by laser irradiation from one direction may be used as a welding target.

In this case, if the size of the straight portion is set to be more than one time and twice or less the size that can be welded only by the laser from one direction, the laser does not penetrate the welding object. Therefore, no dent is generated on the back surface of the welding object.

[0038]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory view of a laser butt welding method according to a first embodiment of the present invention, and FIGS. 3 and 4 are explanatory views and experiments of an experiment for deriving the principle of the first embodiment of the present invention. It is a graph which shows data.

In FIG. 3, the molten metal width d is the bottom surface (groove bottom) of the V-shaped portion in the abutting portion of the base materials 8, that is, the boundary portion between the V-shaped portion and the straight portion. The width in a direction substantially perpendicular to the length direction of the straight portion.

The back bead position indicates the distance (mm) from the back surface of the base material 8 to the most recessed portion of the recess formed in the molten metal 7.

The welding conditions in this experiment are as follows. The laser 5 irradiates from the V-shaped portion side of the groove, the output of the laser 5 is 5 kW, and the welding speed is 1.0 m / m.
In, the focus position of the laser 5 is the groove bottom, the route length is 4 mm, and the laser beam angle is 15 °.

As shown in FIG. 4, the molten metal width d is 2 mm.
Beyond, the back bead position became a negative value, that is, a back wave could be generated.

This is because when the width d of the molten metal exceeds 2 mm, the increase in h is suppressed in the capillary phenomenon shown in FIG. 20, and the molten metal melted by the laser 5 is pulled upward by the capillary embankment. Because there is no.

Therefore, the bottom of the molten metal does not have a shape pulled upward, and as shown in FIG.
Since gravity 9 which is a downward force acts on the molten metal 7, the molten metal 7 that has been heated and melted into a liquid by laser irradiation is pulled downward by gravity.

When the molten metal 7 melts down on the back side of the base material 8 and comes into contact with the atmosphere, it instantaneously solidifies due to the temperature difference, and a stable backwash can be formed.

Therefore, as shown in FIG. 1, the Y-shaped groove portion of the base material 8 is formed so that the width (the molten metal width d) of the bottom surface 13 of the V-shaped portion is 2 mm or more. Laser irradiation is performed from the V-shaped portion to weld the straight portion 14.

In this case, from the above experimental results, no dent is formed on the back surface of the base material 8 as in the prior art. For this reason, after welding the straight part 14 with the laser 5 from the groove side, the step of forming an excess on the back surface of the base material 8 with an arc heat source or a laser, which is conventionally performed, becomes unnecessary.

Then, after welding the straight portion 14 with the laser 5 from the groove side, as shown in FIG. 2, the V-shaped portion 15 is welded with the laser 5 and the filler 12 or the like.

As described above, according to the first embodiment of the present invention, the Y-shaped groove portion of the base material 8 is formed so that the width of the bottom surface 13 of the V-shaped portion is 2 mm or more. Since laser irradiation is performed from the V-shaped portion and the straight portion 14 is welded, no dent is generated on the back surface of the base material 8.

For this reason, after welding the straight portion 14 with the laser 5 from the groove side, there is no need to form a margin on the back surface of the base material 8 with an arc heat source or laser.
The welding process includes a first process for welding the straight portion 14 and a second process for welding the V-shaped portion, and one process is not required as compared with the conventional technology.

Therefore, according to the first embodiment of the present invention, a butt welding method using a laser capable of reducing the number of welding steps and improving the working efficiency, and capable of forming a stable margin is provided. Can be realized.

The angle θ of the V-shaped portion (groove angle) may be set to 15 ° or more from the viewpoint of welding efficiency and heat input if the angle of the laser beam is 15 °. preferable.

Further, in the above-described example, the butted shape is the Y shape, but the present invention is applicable to other shapes.

6 to 9 are diagrams showing examples of shapes in which the butted shapes are other than the Y shape. FIG. 6 shows an example in which the groove portion has a wall surface that is substantially perpendicular to the surface of the base material 8. In this case, the width d of the bottom surface 13 is assumed to exceed 2 mm.

FIG. 7 shows an example in which the groove portion is stepped. In this case as well, the width d of the bottom surface 13 is also shown.
Shall exceed 2 mm. FIG. 8 shows an example in which the groove portion has a curved shape. In this case as well, it is assumed that the width d of the bottom surface 13 exceeds 2 mm.

FIG. 9 shows an example in which the groove portion is curved, but unlike the example in FIG. 8, the bottom surface 13 is not linear. In the example of FIG. 9, the curve of the groove portion is formed so that the straight portion 14 has a radius of curvature that does not cause capillary reduction.

Next, a butt welding method using a laser according to a second embodiment of the present invention will be described.

When butt welding a thick plate, the groove is set to Y
When performing the first step of completely welding the straight portion of the butt surface in a groove shape having an opening at the top and a straight portion at the bottom, such as a mold, and having a sharp bevel angle, FIG.
As shown at 0, the laser 5 is irradiated upward from the back side of the base material 8, that is, irradiated from the straight portion 14 side.

Next, in the second step, the inside of the groove from the opening on the surface of the base material 8 to the straight portion 14 is welded by using both laser and gas shielded arc welding, or by filler welding using both laser and filler wire. By burying it, butt welding of a thick plate is enabled.

For completely welding the straight portion 14,
By irradiating the base material 8 with the laser in the first step upward from the back side, the molten metal 7 melted by the laser 5 causes gravity 9 to act downward as shown in FIG.
The molten metal 7 that has become liquid is pulled downward by gravity 9.

Then, the molten metal 7 melts down on the laser irradiation surface, and is instantaneously solidified by a cooling effect due to a temperature difference between the molten metal 7 and the shield gas and the atmosphere, so that a margin is formed on the laser irradiation side.

As described above, according to the second embodiment of the present invention, in the first step of welding the Y-shaped butt portion by the laser, the straight portion side of the Y-shaped portion (the back surface of the base material 8) Side), the straight portion is welded by laser, and then, in the second step, the V-shaped portion of the Y-shaped portion is welded.
Since the mold portion is configured to be welded, a process of forming an extra layer on the back surface of the base material 8 by using an arc heat source or a laser is unnecessary, and a welding process includes a first process of welding the straight portion 14 and a V-shaped process. There are two steps, a second step for welding the part, and one step is not required as compared with the prior art.

Therefore, also in the second embodiment of the present invention, as in the first embodiment, the number of welding steps can be reduced to improve the working efficiency, and a stable margin can be formed. A possible laser butt welding method can be realized.

It is desirable that the groove angle be as small as possible in order to reduce the influence of heat, the amount of welding, and the welding time. However, the groove is irradiated by irradiating a laser upward from the bottom toward the straight portion of the Y groove. Irrespective of the angle, the range of the groove angle depends on the welding method for filling the V groove in the second step.

In the case of the Y-groove, if the angle of the groove is made smaller than necessary, an unwelded portion occurs at the bottom of the groove in the conventional welding method, resulting in welding defects. Of 10 °, which is difficult.

On the other hand, according to the second embodiment of the present invention, after the straight portion is welded from the back side of the base material 8, the V-shaped portion is welded.
By using laser and arc combined welding or laser and filler combined welding, the groove angle can be minimized to 1
Welding of a narrow groove of 0 ° becomes possible.

That is, when the laser and the arc are combined, the plasma generated by the arc is guided to the bottom of the groove by the laser. Can be filled with a groove.

In the case of filler welding using both a laser and a filler, the groove serves as a guide for inserting the filler wire deep into the groove, and the narrower the groove angle, the more accurate the guide becomes. By irradiating the laser with the wire inserted into the deep bottom of the groove, the inside of the groove can be filled.

It should be noted that also in the second embodiment, Y
Not only the butt of the mold shapes but also the shapes shown in FIGS. 6 to 9 can be welded.

In the case where the groove shape is not Y-groove and the groove shape has a straight portion below as shown in FIG. 6, the straight portion is completely welded by laser in the first step. Therefore, the preferred size of the groove shape above the straight portion depends on the combined use of laser and filler or the combined use of laser and arc in the second step.

The width of the opening above the straight portion is desirably as narrow as possible in order to reduce the amount of welding in consideration of the thermal influence of the molten metal and the shortening of the welding time. There is a limit to the minimum width and depth to width that the laser can pull the arc plasma into the groove.

For this reason, the opening above the straight portion is
When welding and printing using a laser and an arc together, it is preferable that the opening width is 3.5 mm or more and the groove depth is 20 mm to 17 mm or less.
Filling with the weld metal inside the groove becomes possible.

Incidentally, as in the second embodiment, the first
In the process, when the straight portion is welded from the back surface (straight portion side) of the base material 8 by laser, the cross section of the welded portion has triangular weld metal traces with the groove side upward. .

In the second embodiment of the present invention, the straight portion is welded in the first step and the groove is welded in the second step. However, the groove is welded in the first step. The straight portion may be welded by laser from the back surface of the base material 8 in the second step.

FIGS. 11 to 14 are explanatory views of a butt welding method using a laser according to a third embodiment of the present invention.

In the butt welding of a thick plate material, a plate material having a thickness larger than a thickness which can be welded only by laser irradiation from one direction may be used as the welding target 8.

In this case, the object 8 to be welded is so dimensioned that the straight portion can be welded only by laser from one direction.
It is possible to process.

However, in the case where the straight portion has a dimension larger than that which can be welded only by the laser from one direction, that is, as shown in FIG. 11, the dimension L2 of the straight portion is welded only by the laser from one direction. If it is more than the obtainable dimension L1,
The laser 5 does not penetrate the welding object 8.

Therefore, at this point, the welding object 8
No dents occur on the back surface of the.

Subsequently, as shown in FIG. 12, the laser 5 is irradiated from the back surface of the welding object 8. In this case, since the portion previously melted by the laser irradiation from the surface of the welding object 8 has already sufficiently solidified, the laser 5 does not penetrate through the welding object 8 and the molten metal Can be prevented from being generated by being pulled up. At this time, the molten metal is pulled down by gravity.

Then, the molten metal that has melted to the back side due to the cooling effect due to the temperature difference between the molten metal, the shielding gas and the atmosphere can instantaneously solidify and form a margin on the laser irradiation side.

For this reason, a step for forming a margin on the back surface of the welding object is not required, and the number of welding steps can be reduced.

However, the dimension L2-L1 should be smaller than the dimension that can be welded only by laser from one direction. Therefore, the dimension L2 is more than one time and less than or equal to two times the dimension that can be welded only by a laser from one direction.

Next, as shown in FIG. 13, the V-shaped part is
Welding is performed using the laser 5 and the arc welding torch 16.

Instead of the welding method shown in FIG.
As shown in FIG.
7 can be used for welding.

When the V-shaped portion is welded by the method shown in FIG. 13 or FIG. 14, a weld having a sectional shape as shown in FIG. 15 is obtained.

As described above, according to the third embodiment of the present invention, the straight portion of the Y groove is more than one time and less than twice the size that can be welded only by laser from one direction. A butt shape is formed so as to have dimensions, and after irradiating the laser from the front side of the welding object 8, the laser is irradiated from the back side to weld the straight portion.

Accordingly, it is possible to improve the working efficiency by reducing the number of welding steps, and to realize a butt welding method using a laser capable of forming a stable margin.

In the third embodiment, as in the second embodiment, even if the V-shaped portion has an acute angle, it is possible to form a stable extra bank.

For this reason, according to the third embodiment,
It is possible to realize a butt welding method using a laser that can secure a margin while reducing the embedding amount of the V-shaped portion.

In the welding of the V-shaped part, when a laser and an arc are combined, the plasma generated by the arc is guided to the bottom of the groove by the laser.
Even in an ultra-narrow groove, which was difficult to melt by conventional arc welding of 10 °, the V-shaped portion can be filled.

[0092] In the case of filler welding using both a laser and a filler, the groove serves as a guide for inserting the filler wire deep into the groove, and the narrower the groove angle, the more accurate the guide becomes. By irradiating the laser with the laser inserted into the bottom of the groove, the inside of the groove can be filled.

FIGS. 16 and 17 are explanatory views of a butt welding method using a laser according to a fourth embodiment of the present invention.

The fourth embodiment is different from the third embodiment in that the laser irradiation is performed first from the back surface of the welding object 8, and the other conditions are as follows. This is the same as the embodiment.

That is, as shown in FIG. 16, the straight portion is made to have a size that can be welded only by the laser from one direction, and the laser is irradiated from the back surface of the welding object 8. In this case, the laser 5 does not penetrate the welding object 8, and no dent is generated on the back surface of the welding object 8. At this time, the molten metal is pulled down by gravity, and the molten metal that has melted to the back side due to the cooling effect due to the temperature difference between the molten metal and the shield gas and the atmosphere instantaneously solidifies and forms a margin on the laser irradiation side Can be.

Subsequently, as shown in FIG. 17, the laser 5 is irradiated from the surface of the welding object 8. In this case, since the portion previously melted by the laser irradiation from the back surface of the welding object 8 has already been sufficiently solidified, the laser 5 does not penetrate the welding object 8.

For this reason, a step for forming a margin on the back surface of the welding object is not required, and the number of welding steps can be reduced.

Next, as shown in FIG. 13 or FIG. 14, the V-shaped portion is welded using the laser 5 and the arc welding torch 12 or the laser 5 and the filler wire 16.

Then, when the V-shaped portion is welded by the method shown in FIG. 13 or FIG. 14, a weld having a sectional shape as shown in FIG. 15 is obtained.

As described above, according to the fourth embodiment of the present invention, the straight portion of the Y groove is more than one time and less than twice the size that can be welded only by laser from one direction. The butt shape is formed so as to have the dimensions, and after the laser is irradiated from the back side of the welding object 8, the laser is irradiated from the front side to weld the straight portion.

Therefore, it is possible to improve the working efficiency by reducing the number of welding steps, and to realize a butt welding method using a laser capable of forming a stable margin.

In the fourth embodiment described above, as in the third embodiment, even when the V-shaped portion is at an acute angle, it is possible to form a stable extra bank and to embed the V-shaped portion. It is possible to realize a butt welding method using a laser capable of securing a margin while reducing the amount.

In the third and fourth embodiments described above, the abutting shapes shown in FIGS. 6 to 9 are also applicable.

[0104]

According to the present invention, it is possible to improve the working efficiency by reducing the number of welding steps, and to realize a butt welding method using a laser capable of forming a stable margin.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a butt welding method using a laser according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating welding of a V-shaped portion according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of an experiment for deriving the principle of the first embodiment of the present invention.

FIG. 4 is a graph showing experimental data for deriving the principle of the first embodiment of the present invention.

FIG. 5 is a diagram illustrating the principle of the first embodiment of the present invention.

FIG. 6 is a diagram showing an example of a butted shape to which the present invention is applied.

FIG. 7 is a diagram showing another example of a butt shape to which the present invention is applied.

FIG. 8 is a diagram showing still another example of a butted shape to which the present invention is applied.

FIG. 9 is a diagram showing still another example of a butted shape to which the present invention is applied.

FIG. 10 is an explanatory diagram of a second embodiment of the present invention.

FIG. 11 is an explanatory diagram of one process in a third embodiment of the present invention.

FIG. 12 is an explanatory diagram of another step in the third embodiment of the present invention.

FIG. 13 is an explanatory diagram of another step in the third embodiment of the present invention.

FIG. 14 is an explanatory diagram of another step in the third embodiment of the present invention.

FIG. 15 is an explanatory diagram of a cross-sectional shape of an object to be welded according to a third embodiment of the present invention.

FIG. 16 is an explanatory diagram of one process in a fourth embodiment of the present invention.

FIG. 17 is an explanatory diagram of another step in the fourth embodiment of the present invention.

FIG. 18 is an explanatory diagram of a phenomenon that occurs when laser welding is performed.

FIG. 19 is a diagram showing a state in which the angle of the Y groove is narrow.

FIG. 20 is an explanatory diagram of a capillary phenomenon that occurs when welding the straight portion of the Y groove.

FIG. 21 is an explanatory view of the occurrence of a depression on the back surface when welding the straight portion of the Y groove.

FIG. 22 is an explanatory diagram of an operation for correcting a dent when a dent occurs on the back surface.

[Explanation of symbols]

 5 Laser 7 Molten metal 8 Base material 9 Gravity 12 Filler 13 Bottom surface 14 Straight part 15 V-shaped part 16 Arc welding torch 17 Filler wire

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeyuki Sakurai 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 4E001 AA03 BB06 DA01 4E068 AA05 BA06 BC01 BE00 BE03

Claims (5)

[Claims] 1. A butt-welding method using a laser to weld the straight portion with a laser, wherein the width of the groove bottom surface is reduced by laser. A butt welding method using a laser, characterized in that a straight portion has a dimension not to cause a capillary phenomenon when welding. 2. A butt-welding method using a laser for welding a straight portion with a laser, wherein the straight portion is welded to the straight portion with a laser. ,
A butt welding method using a laser, wherein the straight portion is formed from a wall surface having a radius of curvature that does not cause capillary action. 3. A butt welding method having a groove shape having both an opening and a straight portion. In a butt welding method using a laser for welding the straight portion with a laser, Irradiate the laser from the opposite surface, weld the straight part, from the surface where the opening is formed, perform laser welding with a gas shielded arc or filler welding by using a laser and a filler wire together, A butt welding method using a laser, wherein the inside of the groove is filled with welding. 4. A butt-welding method using a laser, wherein the straight portion is welded with a laser, wherein the straight portion is welded by the laser alone. The length is more than 1 time and less than 2 times as long as possible, and the straight part is partially welded by irradiating laser from the side of the butted surface where the opening is formed, and the surface where the opening is formed. Laser is irradiated from the opposite side to weld the straight part, and from the surface where the opening is formed, laser welding with gas shield arc or filler welding using laser with filler wire is performed. Butt welding method using a laser, wherein the inside of the groove is filled with welding. 5. A butt-welding method having a groove shape having both an opening and a straight portion, wherein the straight portion is welded by a laser alone. The length is more than 1 time and not more than 2 times as long as possible, and the straight portion is partially welded by irradiating a laser from the surface of the butted surface opposite to the surface where the opening is formed. Irradiate the laser from the surface where is formed, weld the straight part, and perform filler welding by combined use of laser and gas shield arc or combined use of laser and filler wire from the surface where the opening is formed, A butt welding method using a laser, wherein the inside of the groove is filled with welding.