JP2012143765A - Laser welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser welding method that prevents a laser beam from going through a gap even in a state that the gap exists though the laser beam goes through a gap portion (which causes poor welding) if the gap exists in abutment parts of both base materials to be welded when performing laser welding.SOLUTION: When respective abutment faces 11, 21 of the two base materials 1, 2 are welded by this laser welding method in which the welding is successively continuously performed from a welding start position to a welding end position side while molten metal molten by the laser beam R is supplied between the respective abutment faces in a state that the route gap S is formed between the respective abutment faces 11, 21, the welding is performed in a state that the abutment faces 11, 21 are inclined downward by a prescribed angle as a welding position goes from the welding start position to the welding end position, so that the abutment faces 11, 21 of both the base materials 1, 2 can be certainly welded even in the state that the route gap S exists.

Description

  The present invention is a state in which a root gap is provided between the butt surfaces (hereinafter referred to as butt surfaces) of two metal base materials, while supplying molten metal melted by a laser beam between the butt surfaces, from the welding start position. The present invention relates to a laser welding method in which welding is successively performed toward the end of welding.

  The laser welding method of the present application is suitable for welding two abutting surfaces in a state where two base materials (mainly plate materials) are butted against a flat shape, an L shape, a T shape, or the like.

  There are various methods for welding two base materials (metal materials). Among them, the laser welding method can locally heat the abutting surfaces of the two base materials to weld them, so that the heat effect This is a technique that can perform clean and solid welding with few parts.

  Also, in recent years, the increased output of laser welding machines has made it possible to weld the abutting surfaces with a laser beam even if the abutting surface width (plate thickness) between the base materials is relatively wide (for example, about 20 mm width). ing.

  For example, as shown in FIG. 5, this type of laser welding method irradiates the abutting surfaces 11 and 21 (abutting portions) of both base materials 1 and 2 with a laser beam R, and both sides of the abutting portions have a predetermined small width. The two butted surfaces 11 and 21 are fusion welded (abbreviated as fusion welding) by melting them one by one. In the laser welding example of FIG. 5, the long side portions of both long plate materials (base materials) 1 and 2 are joined in a planar shape.

  The focal portion of the laser beam R irradiated during laser welding is generally in a very narrow range having a diameter of 1 mm or less. Therefore, in order to melt the abutting portion to be welded, it is desirable to abut the abutting surfaces 11 and 21 without gaps (for example, I-type joints) over the entire length to be welded.

  By the way, when the shapes of the abutting surfaces 11 and 12 to be welded of both the base materials 1 and 2 are uneven, when the abutting surfaces 11 and 21 of both the base materials are maintained in parallel, As shown by the chain line in FIG. 5, a root gap S may be formed between both abutting surfaces 11 'and 12'.

  If the distance between the root gaps S is larger than the beam diameter (for example, 2 mm or more), the laser beam R cannot pass through the gaps S as shown by the arrow Ra in FIG. become.

  When two base materials are welded to an L shape, if the base material is a plate material, the base material is likely to warp, and when the abutting surfaces of both base materials are abutted, a root gap is formed at the abutting portion. It becomes easy to do. In addition, in the case where the base material is subjected to press work (for example, L-shaped bending), processing tolerance is likely to occur in the portion to be welded by the press work, and also in this case when the abutting surfaces of both base materials are abutted In addition, a root gap is easily formed at the abutting portion.

  By the way, when the welding surfaces of the two base materials 1 and 2 are laser-welded, if there is a root gap S (for example, an interval of 2 mm or more) between the both facing surfaces 11 and 21, the gap S portion. The laser beam R passes through (it is difficult to melt the butt surface of the base material), and welding becomes impossible (or poor welding).

  Therefore, in laser welding, the respective welding surfaces (butting surfaces) 11 and 21 of both base materials 1 and 2 are machined (for example, cut into an I-type joint) so as to butt without gaps over the entire length to be welded. However, machining of the I-type joint is troublesome, and in particular, in the case of a base material having a long portion that requires welding, each of the abutting surfaces 11 and 21 is made into an I-type joint over the entire length. There is a problem that machining (shaving) is very difficult and requires a lot of labor.

  Therefore, the present invention does not perform machining (for example, cut into an I-type joint) to abut the abutting surfaces of both base materials without a gap, in other words, a little spacing is provided between the abutting portions of both base materials. An object of the present invention is to provide a laser welding method in which the route gap portion can be favorably welded by a relatively simple method even in a state where there is a route gap.

  The present invention has the following configuration as means for solving the above problems. The present invention is directed to a laser welding method in which abutting surfaces having a root gap between two base materials are successively welded by a laser beam from a welding start position toward a welding end side.

  When performing laser welding, as described in the above section “Problems to be Solved by the Invention”, machining (for example, I) is performed so that the abutting surfaces to be welded of both base materials can be abutted without gaps. It is desirable to machine the die joints, but especially when the welded parts of both base materials are very long, machining to make the abutting surfaces butt without gaps over the entire length of the welded parts. It is very cumbersome to do.

  Therefore, in the laser welding method of the present invention, the abutting surfaces of the two base materials are not precisely machined into the same shape (for example, an I-type joint), and a slight gap (for example, about 2 mm) is provided between the respective facing surfaces of the two base materials. This is performed in a state in which a route gap is provided.

[Invention of Claim 1 of the Present Application]
In the laser welding method according to the first aspect of the present invention, a molten metal melted by a laser beam is supplied between the abutting surfaces in a state where a root gap is provided between the abutting surfaces of the two base materials. Welding sequentially toward the welding end position side, and in welding the abutting surface, the abutting surface is inclined downward by a predetermined angle from the welding start position toward the welding end position. Is what you do. In the following description, the fact that the abutting surface is inclined downward is sometimes referred to as “downward inclination”.

  A general welding wire can be used as a filler material from which molten metal is melted by a laser beam. This filler material is for supplying molten metal into a groove portion having a root gap. And this melt material is sent to a laser beam irradiation position for every part melted with progress of laser welding.

  In the laser welding method of claim 1 of the present application, first, in a state where a root gap is provided between the abutting surfaces of both base materials, the laser beam irradiation position and the tip of the filler metal are set at the welding start position, and laser welding is performed therefrom. To start. At this time, the abutting surface is lowered and inclined by a predetermined angle from the welding start position toward the welding end position.

  And when laser welding is started, the melted material is melted by the energy (heat) of the laser beam and a molten filler material (hereinafter sometimes referred to as a molten pool) is supplied between the abutting surfaces. At this time, the molten pool is supplied to a position immediately before the laser beam irradiation position. As a result, the laser beam irradiates the molten pool, so that the energy (heat) of the laser beam is conducted to the abutting surfaces of the two base materials through the molten pool to melt the both abutting surfaces.

  By the way, the metal near the front and rear of the laser beam irradiation position melts by heat conduction (becomes a molten pool), but when the metal melts, it has fluidity and has a property that its volume is slightly increased due to thermal expansion. is doing.

  In the laser welding method of the present application, since the abutting surface is lowered and inclined by a predetermined angle from the welding start position toward the welding end position, the molten pool has a root gap before the laser beam irradiation position moves. Will flow down to the descending slope side. That is, the molten pool easily flows in the route gap portion toward the welding progress side (downward tilt side) due to gravity, and the molten pool sequentially fills the groove portion immediately before the laser beam irradiation position.

  As described above, when the weld pool sequentially fills the groove immediately before the laser beam irradiation position, the laser beam is prevented from passing through (the laser beam is reliably irradiated to the weld pool), and the energy of the laser beam The base material both abutting surfaces in the vicinity of the welding progress side can be sequentially and reliably melted through the molten pool. Therefore, it is possible to achieve good fusion welding over the entire length of the welded portion without cutting the abutting surfaces of both base materials into the same shape (for example, an I-type joint) with high accuracy.

[Invention of claim 2 of the present application]
The invention of claim 2 of the present application is such that in the laser welding method of claim 1, the angle at which the abutting surfaces of both base metals are inclined downward is in the range of 15 ° to 45 °. If the angle at which the abutting surface is inclined downward is less than 15 °, the speed at which the molten pool flows down becomes too slow to advance ahead of the laser beam, and the laser beam passes through the root gap. Become. On the other hand, when the angle at which the abutting surface is inclined downward exceeds 45 °, the flow rate of the molten filler material (molten pool) increases, and the molten pool moves away from the laser beam irradiation position quickly (the molten pool becomes faster). In addition to the problem that the function of melting the base material by the molten pool is lowered and the reliability of welding is inferior, the operation of moving the laser beam and the filler metal becomes difficult, and the workability is improved. There is also the problem of getting worse.

[Effect of the invention of claim 1 of the present application]
In the laser welding method according to claim 1 of the present invention, welding is performed from a welding start position while supplying a melted metal melted by a laser beam between each abutting surfaces in a state where a root gap is provided between each abutting surfaces of two base materials. When welding sequentially and continuously toward the end position, the abutting surfaces are inclined downward by a predetermined angle from the welding start position toward the welding end position.

  As described above, when laser welding is performed with the welding progress side inclined downward, the molten pool easily flows down to the groove portion immediately before the laser beam irradiation position as described above. It will be surely filled sequentially.

  Therefore, in the laser welding method according to claim 1 of the present application, a long method, which has been considered difficult in the past, is a simple method in which the abutting surfaces of both base materials are inclined downward by a predetermined angle from the welding start position toward the welding end position. There is an effect that laser welding can be continuously performed on the root gap and a good weld can be obtained.

  Further, in the laser welding method of claim 1 of the present application, since laser welding can be performed with a root gap provided between the abutting surfaces of both base materials, laser welding is possible even if the shape of each abutting surface is somewhat uneven. Therefore, there is an effect that machining (for example, shaving for an I-type joint) for causing the abutting surfaces to abut each other without a gap becomes unnecessary.

[Effect of the invention of claim 2 of the present application]
The laser welding method according to claim 2 of the present application is such that welding is performed in the above-described claim 1 in a state where the angle at which the abutting surface is inclined downward is set in a range of 15 ° to 45 °.

  By the way, if the downward inclination angle of the abutting surface is less than 15 °, the speed at which the molten filler material (molten pool) flows down becomes too slow to be ahead of the laser beam, and the laser beam passes through the root gap. It will end up. On the other hand, when the angle at which the abutting surface is inclined downward exceeds 45 °, the flow rate of the molten filler material (molten pool) increases, and the molten pool moves away from the laser beam irradiation position quickly (the molten pool becomes faster). In addition to the problem that the function of melting the base material by the molten pool is lowered and the reliability of welding is inferior, the operation of moving the laser beam and the filler metal becomes difficult, and the workability is improved. There is also the problem of getting worse.

  Therefore, in the laser welding method according to the second aspect, in addition to the effect of the first aspect, since the flow velocity of the molten pool can be properly maintained, the laser beam is welded from the welding start position without passing through the root gap. There is an effect that appropriate welding can be performed up to the end position.

It is a perspective view for demonstrating the laser welding method of this-application Example. It is the II-II expanded sectional view of FIG. It is the III-III expanded sectional view of FIG. It is IV-IV sectional drawing of FIG. It is explanatory drawing of the conventional laser welding method. It is explanatory drawing in case there exists a root gap between the butt | matching surfaces of both base materials of FIG.

[Example]
The laser welding method of the present embodiment will be described with reference to FIGS. This embodiment (FIGS. 1 to 4) corresponds to claims 1 and 2 of the present application.

  FIG. 1 shows a case where two base materials 1 and 2 each made of a long plate material are juxtaposed in a plane and their long side portions are laser-welded.

  By the way, as a background regarding the laser welding method of the present application, there is the following as described in the above [Background Art] section.

  That is, as shown in FIG. 6, the focal portion of the laser beam R irradiated at the time of laser welding is generally a very narrow range having a diameter of 1 mm or less, and when two base materials 1 and 2 are laser welded, In addition, it is desirable to perform machining (cutting into an I-type joint) to butt the respective abutting surfaces 11 and 21 to be welded without gaps. Very troublesome.

  When the abutting surfaces 11 and 21 to be welded are not aligned, a root gap S is formed at the abutting portion. However, if laser welding is performed with the root gap S remaining at the abutting portion, the gap portion is formed. Since the laser beam passes through, welding is impossible (see arrow Ra in FIG. 6).

  Therefore, in the laser welding method of this embodiment, as shown in FIG. 1, the base materials 1 and 2 to be welded are juxtaposed in a state where a small gap root gap S is formed between the respective abutting surfaces 11 and 21; Between the respective abutting surfaces 11 and 21 of the two base materials 1 and 2, the filler material 3 (which becomes the molten pool Ba in FIGS. 3 and 4) melted by the laser beam R along the abutting surfaces 11 and 21. While being supplied, welding is successively performed from the welding start position toward the welding end position. In the laser welding method of this embodiment, when starting welding, the abutting surfaces 11 and 21 are inclined downward by a predetermined angle θ (see FIGS. 1 and 3) from the welding start position toward the welding end position. I try to do in the state.

  The distance between the root gaps S is suitably up to about 2 mm. Further, in this embodiment, the abutting surfaces 11 and 21 of both base materials 1 and 2 are slightly inclined (for example, 2.5 °) to the thickness portion of the upper side 2/3 as shown in an enlarged view in FIG. The inclined surfaces 11a and 21a are provided, and the thickness portion on the lower side １ ／ is the vertical surfaces 11b and 21b. Therefore, in a state where both the abutting surfaces 11 and 21 are close to each other, a groove portion having an angle of about 5 ° is formed on the upper side as shown in FIG.

  In the laser welding method of this embodiment (FIGS. 1 to 4), a nozzle 4 for injecting a shield gas (symbol G in FIGS. 1 and 3) to the irradiation position of the laser beam R, and a filler material 3 to be a molten pool And using.

  The shield gas G ejected from the nozzle 4 is a gas, such as carbon dioxide or argon gas, for preventing the surface of the weld bead B that becomes hot from being oxidized.

  As the filler material 3, a general welding wire can be used. This filler material 3 is for supplying molten metal into the groove portion of the root gap S as will be described later. And this melt material 3 is sent to a laser beam irradiation position for every part melted with progress of laser welding.

  The laser welding method of this embodiment is performed as follows. First, as shown in FIG. 1, both base materials 1 and 2 to be welded are parallel to each other in a state in which a route gap S of a predetermined small interval (for example, an interval of 2 mm) is provided between the abutting surfaces 11 and 21. The position is held in the posture and the posture where the abutting surfaces 11 and 21 are inclined downward by a predetermined angle θ. In this case, the downward inclination angle θ is suitably in the range of 15 ° to 45 °.

  In this state, the laser beam R irradiated from the laser beam irradiation apparatus is set so as to be irradiated to the welding start position, and the traveling path and traveling speed of the laser beam R are designated. The traveling path of the laser beam R is set to be parallel to the descending inclination angle θ (see FIGS. 1 and 3) of the abutting surfaces 11 and 21.

  Further, the filler material 3 is set so that the tip thereof is positioned immediately below the laser beam irradiation position. The filler material 3 is moved toward the end of welding with the progress of the laser beam, but is sequentially fed out by the length of consumption.

  When the laser welding operation is started after these sets are completed, the filler material 3 is sequentially melted by the energy (heat) of the laser beam R as shown in FIG. 3 and FIG. The molten pool Ba is formed between the surfaces 11 and 21 to close the gap portion immediately before the laser beam irradiation position. Then, the traveling laser beam R is surely applied to the molten pool Ba, so that the energy (heat) of the laser beam R is conducted to the abutting surfaces 11 and 21 of the base materials 1 and 2 through the molten pool Ba. As a result, the abutting surfaces 11 and 21 are melted by a predetermined width (see the molten pools Bb and Bb in FIG. 4).

  By the way, the metal in the vicinity of the laser beam irradiation position is melted by heat conduction (becomes a molten pool B), but when the metal melts, fluidity is generated and the volume is increased due to thermal expansion. . At this time, since the molten pool B has surface tension acting in the gap, the molten pool B does not flow downward from the gap.

  Then, the laser beam irradiation device (laser beam R) moves in the direction of the arrow in FIG. 3, and at that time, as shown in FIGS. 1 and 3, the abutting surfaces 11 and 21 are moved toward the welding progress side by a predetermined angle θ. Therefore, the molten pool Ba flows prior to the laser beam R to the downward inclination side (arrow A side in FIG. 3). That is, it is easy for the molten pool Ba to flow through the root gap portion toward the welding progress side (arrow A side in FIG. 3) due to gravity, and the molten pool Ba sequentially fills the groove portion immediately before the laser beam irradiation position. become.

  In this way, when the weld pool Ba fills the groove portion immediately before the laser beam irradiation position, the laser beam R is prevented from passing through (the laser beam is reliably irradiated to the weld pool Ba portion), and the laser beam The energy of R can surely and sequentially melt the base material both abutting surfaces 11 and 21 in the vicinity of the welding progress side through the molten pool Ba. Therefore, it is possible to perform good fusion welding over the entire length of the welded portion without machining the abutting surfaces 11 and 21 of both the base materials 1 and 2 to the same shape (for example, I-type joint) with high accuracy.

  As described above, in the laser welding method according to the present embodiment, the butt surfaces 11 and 21 are simply tilted downward by a predetermined angle θ (15 ° to 45 °) from the welding start position toward the welding end position. Thus, there is an effect that laser welding can be continuously performed on the long root gap S, which has been conventionally difficult, and a good welded portion can be obtained.

  Moreover, when the downward inclination angle θ of the abutting surfaces 11 and 21 is set in the range of 15 ° to 45 °, the flow rate of the molten filler material (molten pool Ba) flowing down the root gap portion can be properly maintained, It is possible to efficiently fill the molten pool Ba in the groove portion immediately before the laser beam irradiation position.

  In the above embodiment, both the base materials 1 and 2 are welded in a planar shape. However, the laser welding method of the present application can be applied when both base materials are welded to an L shape, Of course, the present invention can also be applied when welding to a mold.

  1 and 2 are base materials, 3 is a filler material, 11 and 21 are butt surfaces, B, Ba and Bb are weld beads, G is a shield gas, R is a laser beam, S is a root gap, and θ is a predetermined angle. .

Claims (2)

  In a state where a root gap is provided between the respective abutting surfaces of the two base materials, a molten metal melted by a laser beam is supplied between the respective abutting surfaces in succession from the welding start position to the welding end position side. A laser welding method for welding, characterized in that, when welding each abutting surface, the abutting surface is tilted downward by a predetermined angle from the welding start position toward the welding end position. Laser welding method to do.   2. The laser welding method according to claim 1, wherein the predetermined angle for inclining the abutting surfaces is set in a range of 15 [deg.] To 45 [deg.].

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