JP6818575B2 - Overlay welding method for plated steel sheets - Google Patents

Description

The present invention relates to a method for laminating and welding plated steel sheets by joining the laminated plated steel sheets to each other by non-contact welding.

As a method of suppressing welding defects such as blow holes in laser welding, a gap is provided between galvanized steel sheets or the overlapped portion between galvanized steel sheets and other metals so that a gap is provided and laser welding is performed. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 6-7978 (pages 2 to 3, FIG. 1)

In lap welding of plated steel sheets by non-contact welding such as conventional laser welding, shield gas is sprayed only on the surface of the welded surface, and between the lapped steel sheets provided to suppress welding defects such as blow holes. Since the shield gas did not spread to the gaps, there was a problem that burns and rusts were generated at the welded portions in the gaps between the steel plates.

The present invention has been made to solve the above-mentioned problems, and provides high-quality welding in which no burning or rust is generated even on the welded portion of the gap between the overlapped steel plates. The purpose is to obtain a method of lap welding of plated steel sheets by non-contact welding that can be realized.

The lap welding method for plated steel sheets according to the present invention is a lap welding method in which a workpiece having a plating film provided on at least one of the facing surfaces of the first steel plate and the second steel plate laminated through a gap is non-contact welded. Therefore, a shield gas feeding unit for feeding the shield gas into the gap is formed in advance on at least one of the first steel plate and the second steel plate, and between the first steel plate and the second steel plate. The flow path of the shield gas is regulated so that the shield gas supplied from the shield gas supply unit fills the area including the planned welding portion in the gap, and on the downstream side of the flow path, A seal member is provided to form a gas discharge portion for discharging the inflowed shield gas to the outside, and the shield gas supply portion is formed by bending the first steel plate or the second steel plate so as to widen the gap. The welded portion is formed of a tunnel-shaped portion, and the planned welding portion is welded while the shield gas is allowed to flow from the shield gas supply portion into the gap.

According to the present invention, the shield gas sent into the gap between the first steel plate and the second steel plate to be superposed is passed through in a state of being filled in the planned welding location, so that for example, zinc evaporated from the plating layer during welding. The gaseous substance containing the plating metal (referred to as "plating steam" in this document for convenience) is immediately released from the molten location to the gap by the flowing shield gas, so that the reaction between the plating vapor and the molten metal is suppressed. It is possible to obtain high-quality welding in which defects such as blow holes are suppressed and the occurrence of burning and rust is also suppressed.

It is a perspective view for conceptually explaining the main part of the lap welding method of the plated steel sheet which concerns on Embodiment 1 of this invention. It is a perspective view which shows the example which provided the tunnel-shaped part in the 2nd steel plate which becomes the modification of FIG. It is a perspective view which shows the example which provided the tunnel-shaped part on both the 1st steel plate and the 2nd steel plate which are the other modified examples of FIG. It is a perspective view which shows the arrangement of the overlap part of the material to be welded and the seal member in the Example of the layer welding method of the plated steel sheet which concerns on Embodiment 1 of this invention. It is a figure which conceptually shows the arrangement | arrangement of the overlap part of the material to be welded and the seal member in the layer welding method of the plated steel sheet which concerns on Embodiment 2 of this invention, (a) is a front side, (b) is a side surface side. , (C) is the back side. It is a figure which conceptually shows the superposition part of the material to be welded and the arrangement of a seal member which becomes a modification of FIG. 5, (a) is a front side, (b) is a side surface side, (c) is a back side. ..

Embodiment 1.
FIG. 1 is a perspective view for conceptually explaining a main part of a method for laminating and welding a plated steel sheet according to a first embodiment of the present invention, and FIG. 2 shows a tunnel-shaped portion in a second steel sheet which is a modification of FIG. A perspective view showing an example of the provision, FIG. 3 is a perspective view showing an example in which a tunnel-shaped portion is provided on both the first steel plate and the second steel plate, which are other modifications of FIG. 1. In the figure, one of the first steel plate 1 and the second steel plate 2, which are the materials (workpieces) to be welded, which are superposed via a gap S of a predetermined size for allowing the plating vapor to escape, in this case, a predetermined portion of the first steel plate 1. In the above-mentioned gap S, a tunnel-shaped portion 5 constituting a shield gas feeding portion for feeding the shield gas is formed in advance by press working or the like. In the tunnel-shaped portion 5, a predetermined portion of the first steel plate 1 is curved into a semicircular cross section so as to widen the gap S formed between the tunnel-shaped portion 5 and the second steel plate 2, and here, the extending direction of the tunnel is laser welding. It is shaped so as to extend in a direction orthogonal to the welding direction D by the laser beam 8 emitted from the head 7.

In the figure of the first steel plate 1 and the second steel plate 2 which are overlapped, the block-shaped front plate 3A and the rear plate 3B as the sealing members 3 installed on the front side and the rear side are shield gas feeding portions. The flow path of the shield gas is regulated so that the shield gas supplied from the tunnel-shaped portion 5 is filled in the region including the planned welding portion C in the gap S, and the downstream end portion of the flow path. In addition, it has a function of forming a gas discharge unit 6 that discharges the inflowed shield gas to the outside together with the welding-derived gas including the plating vapor generated during welding. Of the gas discharge units 6, the left side portion in the figure is referred to as a gas discharge portion 6a, and the right portion is referred to as a gas discharge portion 6b.

The front plate 3A is in close contact with the front end surface of both the first steel plate 1 and the second steel plate 2 along the front end surface, and the shield gas is applied to the tunnel-shaped portion 5 at a position facing the tunnel-shaped portion 5 in the front plate 3A. A shield gas supply port 5a formed of a through hole for feeding to the gap S is provided. On the other hand, the rear plate 3B is brought into close contact with each other along the rear end surface in the drawings of both the polymerized first steel plate 1 and the second steel plate 2 to close the rear side portion of the gap S. Shielding gas is fed from the shielding gas feed port 5a in the direction of arrow A, fed to the gap S via the tunnel-like portion 5, it flows out from the gas outlet 6 (6a, 6b) in the direction of arrow B1, B2 Will be done.

Next, the tunnel-shaped portion 5 provided in the material to be welded constituting the shield gas feeding portion will be described in detail.
The tunnel-shaped portion 5 serving as the shield gas feeding portion is not limited to the first steel plate 1 side, and may be provided on the second steel plate 2 as in the modified example of FIG. Further, as in the other modification of FIG. 3, both the first steel plate 1 and the second steel plate 2 may be provided with a tunnel-shaped portion 5 serving as a shield gas inflow port. Note that case, according to the shape of the inlet of similarly tunnel-shaped portion 5 and FIG. 1, it is assumed that providing an oval-shaped shielding gas feed port 5a to the front plate 3A.

Further, depending on the welded portion and the weld length, it is assumed that it is difficult for the shield gas to uniformly fill the gap S for releasing the plating vapor between the steel plates. In that case, if necessary, a plurality of tunnel-shaped portions 5 which are shield gas inlets may be provided to allow gas to flow in. In this case, according to the position and shape of the shielding gas inlet of the tunnel-like portion 5, for example, provided a shielding gas feed opening in the front plate 3A, the tunnel-like portion intermediate section of the cross-adjacent if necessary By providing the gas discharge portion, the entire portion including the planned welding portion C in the gap S can be filled with the shield gas.
As a precaution during welding, with respect to the tunnel-shaped portion 5 provided in the first steel plate 1 and the second steel plate 2, the inflow of the shield gas into the gap S is not dammed by welding. When the welding direction is orthogonal to the tunnel direction as shown in FIG. 1, it is necessary to avoid the tunnel-shaped portion 5 for welding.

Next, the first steel plate 1 will be described in detail.
The first steel sheet 1 to be welded is a so-called plated steel sheet, which is obtained by coating the surface of a steel sheet base material made of iron or the like with a thin film made of zinc (or an alloy mainly composed of zinc).
Here, a case where the tunnel-shaped portion 5 for inflowing the shield gas is processed on the first steel plate 1 side as shown in FIG. 1 will be described. A predetermined portion suitable for the welding process determined in advance with respect to the first steel plate 1 so as to project in an arc shape on the side opposite to the surface facing the second steel plate 2 when superposed on the second steel plate 2. The tunnel-shaped portion 5 is formed. The tunnel-shaped portion 5 can be easily formed on a part of the first steel plate 1 by, for example, pressing with a convex metal fitting or the like.

Next, the second steel plate 2 will be described in detail.
The second steel sheet 2 to be welded is also a so-called plated steel sheet, in which the surface of a steel plate base material made of iron or the like is coated with a thin film made of zinc (or an alloy mainly composed of zinc).
Here it will be an explanation when processing shielding gas feed port to the second steel plate 2 side as shown in FIG. A tunnel-shaped portion 5 is formed in a part of the second steel plate 2 so as to project on the side opposite to the surface facing the first steel plate 1 when it is overlapped with the first steel plate 1. The tunnel-shaped portion 5 can also be easily formed by press working with, for example, a convex die, as in the case of the first steel plate 1.

Next, the front plate 3A constituting the seal member 3 will be described in detail.
In the front plate 3A, the shield gas flowing into the gap between the first steel plate 1 and the second steel plate 2 which are the materials to be welded is overlapped from the side end portion parallel to the welding direction D of the first steel plate 1 and the second steel plate 2. Installed to limit the direction of outflow to the outside of the mating portion and to form a space uniformly filled with shield gas in the region portion including the planned welding portion C in the gap S between the first steel plate 1 and the second steel plate 2. Will be done. Therefore, it is preferable to use a material for the sealing member 3 that does not deteriorate or damage the surroundings due to radiant heat or conduction heat during welding. For example, a heat-resistant rubber material such as fluororubber or silicon rubber is used. Alternatively, a metal material such as a steel plate or a stainless steel plate, or a hard material such as a ceramic material provided with a heat-resistant rubber material having rubber elasticity on the surface thereof can be preferably used.

When the shield gas supply port 5a is provided in the front plate 3A portion, a hole is formed so as to match the hole position of the tunnel-shaped portion 5 formed in the first steel plate 1 and the second steel plate 2 in a semicircular cross section. .. Further, in the first embodiment, the shield gas supply port 5a has a circular shape, but if the shield gas can flow into the tunnel-shaped portion 5 of the first steel plate 1 and the second steel plate 2, the shape may be changed. The hole is not limited to this, and a hole such as a quadrangle may be used. Further, when the shield gas supply port 5a is provided on the rear plate 3B side, it is not necessary to provide the shield gas supply port 5a on the front plate 3A side.
Further, when the shield gas flows out from the contact portion between the front plate 3A and the side end surface on the front side parallel to the welding direction D of the first steel plate 1 and the second steel plate 2, the first steel plate 1 and the second steel plate 2 Since there is a possibility that the gap S portion cannot be uniformly filled with the shield gas, it is necessary to bring the first steel plate 1 and the second steel plate 2 into close contact with the side end faces parallel to the welding direction D without any gap.

Next, the rear plate 3B constituting the seal member 3 will be described in detail.
The shield gas that has flowed into the gap S between the first steel plate 1 and the second steel plate 2, which is also the rear plate 3B, is the back side of the figure parallel to the welding direction D of the first steel plate 1 and the second steel plate 2. The area including the planned welding point C in the gap S between the first steel plate 1 and the second steel plate 2 is uniformly filled with the shield gas by restricting the outflow from the side end surface of the steel plate to the outside of the overlapped portion. Installed to form. When the shield gas supply port 5a is provided in the rear plate 3B portion, the same hole processing as in the front plate 3A is performed so as to match the hole position of the tunnel-shaped portion 5 formed in the first steel plate 1 and the second steel plate 2. Give. When the shield gas supply port 5a is provided on the front plate 3A side, it is not necessary to provide the shield gas supply port 5a on the rear plate 3B side.

Further, the contact portion adhesion between the rear plate 3B and the side end surface of the polymerized first steel plate 1 and the second steel plate 2 on the rear side may have the same structure as that of the front plate 3A described above. is necessary.
The type of laser and the configuration of the laser welding device are not particularly limited. For example, a laser welding device known to those skilled in the art or various existing laser welding devices can be appropriately selected and used according to the welding target. can do. In order to protect the processed portion from the atmosphere, the laser welding head 7 supplies an inert gas similar to the shield gas sent from the shield gas supply port 5a described above around the laser beam 8 at a low pressure during welding. Those can be preferably used.

Further, as the gas type that can be suitably used as the shield gas, one type or two or more types selected from the group consisting of the inert gases He, Ar, N ₂ and CO ₂ are used. He, Ar, N ₂ , and CO ₂ gases are all industrially produced gases and are easily available, so that the versatility of the present invention can be enhanced.
Further, the welding target is not limited to the galvanized steel sheet, and the same effect can be obtained even if the base steel sheet and the plated metal are other materials.

Next, the welding method according to the first embodiment will be described.
The first steel plate 1 and the second steel plate 2, which are the materials to be welded, are stacked in a state where a gap S for releasing plating vapor is provided as in the conventional welding method. As illustrated in FIGS. 1 to 3, the first steel plate 1 or the second steel plate 2 has a tunnel-shaped portion having a semicircular cross section, which constitutes a shield gas feeding portion for feeding the shield gas into the gap S. 5 is processed in advance by press molding or the like.

Next, the shield gas fed from the shield gas supply port 5a to the tunnel-shaped portion 5 (inflow side) provided on the first steel plate 1 as shown by the arrow A in FIG. 1 is superposed on the first steel plate 1. After flowing into the gap S between the second steel plate 2 and the second steel plate 2, the flow path of the shield gas is regulated so that the gas discharge portions 6 (6a, 6b) at the ends of the gap S are discharged in the directions of arrows B1 and B2. Therefore, as shown in FIG. 1, the block-shaped front plate 3A and the rear plate 3B are brought into close contact with the end faces parallel to the welding direction of the first steel plate 1 and the second steel plate 2 to be welded and are vertical. Place in.

After that, by sending the shield gas from the shield gas pipe (not shown) to the shield gas supply port 5a, the sent shield gas passes through the tunnel-shaped portion 5 and the gap S between the first steel plate 1 and the second steel plate 2 is passed. Gas such as air that initially existed in the gap S in the process of flowing into the portion, flowing in the direction of the gas discharge portion 6 along the welding direction D of the planned welding portion C, and being discharged to the outside from the gas discharge portion 6. Is replaced with the shield gas, and the space in the gap S is uniformly filled with the shield gas. Then, while continuing the supply of the shield gas, the laser beam 8 is irradiated from the laser welding head 7 according to a predetermined program to perform lap welding. When welding is performed in the welding direction D orthogonal to the tunnel-shaped portion 5 provided on the first steel plate 1, the tunnel-shaped portion 5 is avoided and lap welding is performed.

As described above, by irradiating the laser beam 8 along the planned welding portion C near the tunnel-shaped portion 5, the first steel plate 1 and the second steel plate 2 in the irradiated portion are melted and coalesced with each other. The first steel plate 1 and the second steel plate 2 are welded. At the time of melting as described above, in addition to the steel plate portion which is the base material, the plating film such as zinc having a melting point lower than that of the base material naturally melts and vaporizes to generate plating vapor containing zinc. .. The generated plating steam or the gas derived from the plating steam is immediately moved to another part of the gap S in the direction away from the molten portion of the base metal in the gap S filled with the shield gas flowing in from the tunnel-shaped portion 5. By moving in the direction of the gas discharge section 6 along with the constantly flowing shield gas flow and discharging to the outside, for example, the reaction with the base metal of the molten pool is alleviated and a high-quality welded surface is formed. To.

The laser beam 8 from the laser welding head 7 in the laser welding apparatus (not shown) is an arbitrary starting point on the planned welding point C set on the surfaces of the laminated first steel plate 1 and second steel plate 2. Continuously or intermittently while moving relatively on the material to be welded at a predetermined preset and programmed speed along an arbitrary shape path including a straight line, a curved line, and an intermittent portion from the to the end point. Be irradiated. Of course, at the time of laser welding, the side of the material to be welded may be fixed, the laser beam side may be moved, or vice versa.

Next, it will be described in more detail with reference to the specific example of FIG. Note that FIG. 4 is a perspective view showing the arrangement of the overlapped portion of the material to be welded and the seal member 3 in the embodiment of the method of lap welding the plated steel sheet according to the first embodiment of the present invention. In the figure, the welding target of superposition welding is an example in which the size of the first steel plate 1 is smaller than that of the second steel plate 2. The tunnel-shaped portion 5 is formed on the first steel plate 1, and the planned welding portion C is set here parallel to the extending direction of the tunnel-shaped portion 5. In the gap S, a plurality of protrusions (not shown) having a predetermined height dimension by plastic working are provided on the surface of the first steel plate 1 facing the second steel plate 2 at intervals, and the tips of the plurality of protrusions face each other on the mating side. It is formed by contacting the surface.

The size of the gap S can be appropriately determined in the range of, for example, about 0.05 to 0.5 mm, but the size and the thickness of the first steel plate 1 and the second steel plate 2 are all particularly limited. It's not a thing. Further, instead of forming the gap S by protrusions, a sheet, film, tape or other thin leaf material, plate material, spacer or the like having the same thickness as the desired gap size is placed between the facing surfaces as a sealing material (not shown). It may be formed by interposing as. The diameter of the semicircular portion of the tunnel-shaped portion 5 is formed in the range of about 5 to 10 mm, but the size is not particularly limited.

The front plate 3A is placed in close contact with the front end surface of the first steel plate 1 on the upper surface of the second steel plate 2, and the rear plate 3B is placed in close contact with the rear end surface of the first steel plate 1 on the upper surface of the second steel plate 2 as well. Placed. Further, the shield gas supply port 5a provided on the front plate 3A is previously connected to a gas pipe supplied from a shield gas storage tank (not shown) via a pipe, a hose, or the like. Connection pipes or joints may be attached by welding or adhesive. By installing the front plate 3A and the rear plate 3B, the shield gas is sent into the gap S through the tunnel-shaped portion 5 as shown by the arrow A, and is formed at the left and right ends of the first steel plate 1 on the upper surface of the second steel plate 2. A flow path is formed so as to be discharged from the gas discharge unit 6 (6a, 6b) as shown by arrows B1 and B2. In the figure, only the gas discharge portion 6b on the right side is indicated by a reference numeral.

Incidentally, the laser welding apparatus used, a laser oscillator, various mirrors, an optical system including a condenser lens and the like, the welding head driving device for moving the laser welding heads 7 at any desired position, shape and welding positions of the workpieces・ Image recognition processing equipment that monitors the status, various sensors such as temperature sensors, appropriate processing programs and various data are saved, and laser oscillators, welding head drive equipment, etc. are stored based on the recognition results of the image recognition processing equipment. It can be appropriately selected and used from those known or known by those skilled in the art equipped with a control device for controlling the above.

Further, both the first steel plate 1 and the second steel plate 2 do not have to be galvanized steel plates, and the same effect can be obtained even when only one of them is a galvanized steel plate. For example, one may be a galvanized steel sheet and the other may be a steel sheet without a plating film, or a sheet metal whose base material is made of another metal. Further, the galvanized steel sheet may be galvanized on only one side of the steel sheet. However, when a steel plate with galvanized only on one side is overlaid and welded with a steel plate without a plating film on both sides, the plated side is opposed to the other side and overlaid and welded. As a result, the effect of the present invention can be obtained.

Further, the number of steel plates to be stacked may be three or more, and in such a case, when it is necessary to form gaps between the steel plates to be stacked and to supply shield gas to each gap. Easily supplies shield gas to each gap by, for example, providing a slit-shaped through hole in a steel plate excluding both ends in the polymerization direction among three or more steel plates located in the tunnel-shaped portion 5. be able to. When the number of sheets to be polymerized is 3, a method of forming a tunnel-shaped portion 5 on both the first steel plate 1 and the second steel plate 2 shown in FIG. 3 is used, and a third steel plate is polymerized between the two. By doing so, the shield gas can be supplied to both the gap on the side of the first steel plate and the gap on the side of the second steel plate.

As described above, according to the first embodiment, the shield gas sent from the shield gas feeding unit into the gap S between the first steel plate 1 and the second steel plate 2 includes the gap C including the planned welding portion C. By performing laser welding in a state of being filled with S and flowing in the direction of the gas discharge portion 6, the shield gas is applied not only to the surface of the welded surface to which the laser beam is irradiated, but also to the gap between the opposing steel plates. Since it can be spread over the entire S portion, the welded portion of the gap S portion between the steel plates when the plating films are provided on the facing surfaces of the steel plates also evaporates from, for example, a zinc plating layer having a low melting point and a low boiling point. It is possible to realize high-quality welding in which the reaction between the plated steam containing the plated metal and the molten metal is alleviated, defects such as blow holes are suppressed, and the occurrence of rust and burning is also suppressed.

Further, since the shield gas feeding section is formed by forming the first steel plate 1 or the second steel plate 2 by a tunnel-shaped portion 5 curved so as to widen the gap S between the two, the forming process of the shield gas feeding section is simplified. It is easy to carry out.
Further, since the tunnel-shaped portion 5 is formed over substantially the entire length of the plate width in the front-rear direction in the drawing of the first steel plate 1 or the second steel plate 2, the shield gas can be reliably supplied to the entire gap S.
Further, since the tunnel-shaped portion 5 is formed so as to extend in a direction orthogonal to the welding direction D, the welding space in the gap S from the starting point portion to the ending point portion of the welding can be constantly filled with the shield gas. ..

Embodiment 2.
5A and 5B are views conceptually showing the arrangement of the overlapped portion of the material to be welded and the sealing member in the method of lap welding the plated steel sheet according to the second embodiment of the present invention, in which FIG. 5A is the front side and FIG. Is the side surface side, and (c) is the back surface side. 6A and 6B are views conceptually showing the arrangement of the overlapped portion of the material to be welded and the sealing member, which is a modification of FIG. 5, in which FIG. 6A is the front side, FIG. 6B is the side surface, and FIG. 6C is the back surface. On the side. In the second embodiment, the functions of the block-shaped front plate 3A and the rear plate 3B as the sealing member 3 shown in FIG. 4, that is, the shield gas supplied from the tunnel-shaped portion 5 is scheduled to be welded in the gap S. The gas discharge unit 6 (6a, 6a,) which regulates the flow path of the shield gas so as to fill the area including the portion C and discharges the shield gas flowing into the downstream end of the flow path to the outside. The function of forming 6b) is configured by a sealing member 31 having a front sealing material 3C and a rear sealing material 3D, which are different in shape from the first embodiment.

In the figure, the front sealing material 3C is made of a rectangular tape material having substantially the same thickness as the gap S, and is arranged so as to be polymerized through the gap S. It is interposed along the inside of the front end portion of the first steel plate 1 on the surface facing the 2. The rear sealing material 3D has a semicircular rear closing portion 3s that can airtightly close the inner peripheral surface of the tunnel-shaped portion 5 in the central portion of the tape material having substantially the same thickness and length as the front sealing material 3C. It is composed of integrally formed members, and is interposed along the inside of the rear end portion of the first steel plate 1 on the facing surface between the first steel plate 1 and the second steel plate 2. As shown in the modified example of FIG. 6, when the tunnel-shaped portion 5A has a shape in which the rear portion side is closed, the formation of the rear surface closing portion 3s becomes unnecessary, so that the rear surface sealing material 3D is used. It can be easily formed and installed.

When the sealing member 31 is configured to also serve as a means for forming the gap S as the material of the front sealing material 3C and the rear sealing material 3D, it is altered by radiant heat or conduction heat during laser welding or causes damage to the surroundings. For example, commonly used heat-resistant materials such as steel plates, stainless steel plates, and heat-resistant rubber materials such as fluororubber and silicon rubber can be used alone or in combination of a plurality of materials. When provided separately from the means for forming the gap S, for example, a sheet formed of a material having rubber elasticity such as the above-mentioned heat-resistant rubber material, a flexible material such as a fluororesin material, or the like. A thin leaf material such as a film or tape or a plastic material such as a paste-like filler can be preferably used.

Further, the front sealing material 3C and the rear sealing material 3D can be left as they are after the lap welding of the first steel plate 1 and the second steel plate 2 is completed, but if there is a problem if they are left, they should be removed. In order to facilitate, a part of the front sealing material 3C or the rear sealing material 3D is projected to the outside of the overlapping portion of the first steel plate 1 and the second steel plate 2, and the protruding portion serves as a detachable engaging portion. By integrally forming the nails and tongue pieces, the removal process can be facilitated. Other configurations are the same as those in the first embodiment.

The material to be welded formed as described above sends a shield gas, for example, a mixed gas of Ar and N ₂ from the shield gas supply port 5a to the tunnel-shaped portion 5 or the tunnel-shaped portion 5A as in the first embodiment. After filling the welding space in the gap S with the shield gas by discharging the gas from the gas discharge portions 6 (6a, 6b) through the gap S including the planned welding portion C, FIG. 1 while continuing to supply the shield gas. Overlay welding is performed by irradiating the laser beam 8 from the laser welding head 7 of the above along the planned welding location C. The plating steam generated from the galvanized film by the heat of the laser beam is caused by the flow of the shield gas flowing from the tunnel-shaped portion 5 (or the tunnel-shaped portion 5A) in the gas discharge portion 6 direction of the base metal in the gap S. It is moved from the molten portion toward the gas discharge portion 6, for example, the reaction with the base metal of the molten pool is relaxed, and a high-quality welded surface is formed.

As described above, according to the second embodiment, in addition to the same effect as that of the first embodiment, the shield gas supplied from the shield gas supply unit covers the region including the planned welding portion C in the gap S. A front seal is provided with a seal member 31 that regulates the flow path of the shield gas so as to be filled and forms a gas discharge portion 6 that discharges the inflowing shield gas to the outside at the downstream end portion of the flow path. Since it is composed of the material 3C and the rear surface sealing material 3D, the sealing member 31 can be easily installed. Further, when the sealing member 31 is configured to form the means for forming the gap S between the first steel plate 1 and the second steel plate 2, the stamping die and the pressing process for forming the gap S can be omitted. Effects such as reduction of processing cost can be obtained. Further, when the tunnel-shaped portion 5A has a shape in which the rear portion side is closed as in the modified example of FIG. 6, the formation of the rear surface closing portion 3s becomes unnecessary, and the rear surface sealing material 3D is more easily formed and installed. It becomes possible to do.

As described above, according to the method for welding a plated steel sheet according to the present invention, the plating vapor generated during welding is suitably removed to suppress the occurrence of welding defects such as blow holes and spatter, and the first steel sheet 1 and the first steel sheet 1 and the first. (2) Burning and rust can be prevented from occurring at the welded portion of the gap S portion of the steel plate 2, and more accurate welding is possible. Therefore, for example, zinc used for structural members of automobile bodies and materials for buildings. It can be widely applied to welding surface-treated steel sheets such as plated steel sheets.

In the present invention, the embodiments can be freely combined, and the embodiments can be appropriately modified or omitted within the scope of the invention. For example, in the embodiment, an example of welding by a laser beam is shown, but the present invention is not limited to this, and the same effect can be obtained in the case of other non-contact welding such as electron beam welding. Further, the plated steel sheet is not limited to galvanizing.

1 1st steel plate, 2nd steel plate, 3 sealing member, 3A front plate, 3B rear plate,
31 Sealing member, 3C Front sealing material, 3D Rear sealing material, 3s Rear closing part,
5, 5A tunnel-shaped part, 5a shield gas supply port, 6 gas discharge part, 6a gas discharge part, 6b gas discharge part, 7 laser welding head, 8 laser beam, C planned welding location, D welding direction, S gap.

Claims (5)

It is a lap welding method in which a workpiece having a plating film provided on at least one of the facing surfaces of the first steel plate and the second steel plate polymerized through a gap is non-contact welded.
A shield gas supply unit for feeding the shield gas into the gap is formed in advance on at least one of the first steel plate and the second steel plate.
A flow path of the shield gas between the first steel plate and the second steel plate so that the shield gas supplied from the shield gas supply unit fills the area including the planned welding portion in the gap. A seal member is provided on the downstream side of the flow path to form a gas discharge portion for discharging the inflowed shield gas to the outside.
The shield gas feeding portion includes a tunnel-shaped portion formed by bending the first steel plate or the second steel plate so as to widen the gap.
A method for lap welding a plated steel sheet, which comprises welding a planned welding portion while flowing a shield gas from the shield gas feeding portion into the gap. The tunnel-like portion, said first steel plate or lap welding method of plating steel sheet serial placement in claim 1, characterized in that formed over the entire length of the longitudinal direction of the plate width of the second steel plate. The tunnel-like portion, lap welding method of plating steel sheet placing serial to claim 2 having one end side in the direction of the plate width, characterized in that it is closed. Against the welding direction, the tunnel-like portion is lap welding method of plating steel sheet according to any one of until claim 1 or we claim 3, characterized in that it has formed to extend in orthogonal directions. Claims 1 to 4 are characterized in that the sealing member is interposed so as to be sandwiched between the laminated first steel plate and the second steel plate, and is responsible for forming the gap. lap welding method of plating steel sheet according to any one of until.

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