WO2019163949A1

WO2019163949A1 - Lap welding method, and plate-shaped member

Info

Publication number: WO2019163949A1
Application number: PCT/JP2019/006807
Authority: WO
Inventors: 裕企雄佐藤
Original assignee: 三菱電機株式会社
Priority date: 2018-02-26
Filing date: 2019-02-22
Publication date: 2019-08-29
Also published as: JPWO2019163949A1

Abstract

A flat first steel plate (1) and flat portions (4) of a second steel plate (2) in which a recessed portion (3) has been formed are held in close contact with one another. At least one of the first steel plate (1) and the second steel plate (2) has a zinc plating layer. The melting points of the first steel plate (1) and the second steel plate (2) are higher than the boiling point of the zinc plating layer. In a space (5) formed by the recessed portion (3) and the first steel plate (1), a region thereof in which the first steel plate (1) and the second steel plate (2) are not in close contact with one another, and in which a gap therebetween is suitable for welding, is welded by laser irradiation. Vaporized coating vapor generated by the welding escapes into the space (5).

Description

Overlap welding method and plate member

The present invention relates to a lap welding method and a plate member.

It is practiced to superimpose galvanized steel plates widely used for structural members, building materials, etc., and to irradiate the superposed part with laser to perform welding. The boiling point of zinc used for the galvanized steel sheet is about 900 ° C., and the melting point of the steel sheet as the base material is about 1500 ° C. Accordingly, when welding a galvanized steel sheet to a temperature exceeding the melting point of the steel sheet, the zinc is vaporized and becomes steam. When this steam stays in the welded part, a blow hole is formed, and a part of the molten steel sheet is blown off by pressure to generate spatter, which causes welding failure.

This type of phenomenon occurs not only in galvanized steel sheets, but also when welding metal members having a coating layer with a boiling point lower than the melting point of the base material.

For this reason, measures are taken to release the vapor whose coating is vaporized by welding from the welded part. In general, a gap is provided between the members to be overlapped by using a spacer, a jig, or the like so that the vapor is released from the gap.
In Patent Document 1, a protrusion is formed on one galvanized steel sheet and a recess is formed on the other galvanized steel sheet, and the protrusion is engaged with the recess to form a gap between the two galvanized steel sheets. A method for releasing zinc vapor from the gap to the outside is disclosed.

JP 2013-237053 A

However, if spacers, jigs, etc. are used to provide gaps between the members to be welded on top of each other, the cost increases, and maintaining the gaps is also difficult, so it is difficult to maintain the welding quality. Furthermore, since there is a gap between the members, there is a problem that it is easy to allow deformation of the member due to heat of welding, and high quality welding cannot be obtained.

Further, since the method disclosed in Patent Document 1 is a method of forming a protrusion and a depression on a steel plate to provide a gap, it cannot be used for welding a member that is required to be flat.

The present invention has been made in view of the above circumstances, and even when a member is required to have at least one flat surface, the member can be prevented from being deformed by steam generated by heat during welding. It aims at providing a quality welding method and a plate-shaped member.

In order to achieve the above object, according to the present invention, a method of superposing and welding a first member and a second member includes at least one of the first member and the second member having a coating layer. The melting points of the first member and the second member are higher than the boiling point of the coating layer, and the flat portion of the first member and the flat portion around the recess formed in the second member are held in close contact with each other. Then, the welding target area of the first member and the second member in the space formed by the recess and the flat portion of the first member is melted.

According to the present invention, even if one of the members is required to be flat, welding defects are prevented by letting the vapor of the coating vaporized by welding escape into the space formed by the flat portion and the concave portion. Thus, it is possible to realize high-quality welding that can prevent the member from being deformed by heat during welding.

Sectional drawing of each steel plate welded by the welding method which concerns on embodiment of this invention Sectional drawing of the steel plate of the state closely_contact | adhered and which is one of the processes of the welding method which concerns on embodiment of this invention Sectional drawing of the steel plate of the state welded which is one of the processes of the welding method which concerns on embodiment of this invention (A)-(e) is a top view which illustrates the recessed part formed in a steel plate by the welding method which concerns on embodiment of this invention The perspective view of the appearance panel welded by the welding method concerning the example of the present invention The perspective view of the appearance panel welded by the welding method concerning the example of the present invention

Hereinafter, the lap welding method and the plate-like member according to the embodiment of the present invention will be described.

In this embodiment, it is assumed that a member to be welded in an overlapping manner is a steel plate, and both surfaces are substantially covered with galvanizing. This is called a galvanized steel sheet, and the surface of an iron plate base material mainly composed of iron is coated with a coating layer of zinc or an alloy mainly composed of zinc.

As shown in FIG. 1, the first steel plate 1 is formed flat. On the other hand, the second steel plate 2 is formed with a recess 3, and a flat portion 4 is disposed around the recess 3. The cross section of the recess 3 is formed in a curved shape. The method of forming the recess 3 in the second steel plate 2 is suitable for plastic working, for example, press working. Although the concave portion 3 shown in FIG. 1 is accompanied by the convex portion 3a, only the concave portion 3 may be formed without the convex portion 3a. Moreover, it is also possible to form the recessed part 3 by cutting in a steel plate, and to coat | cover zinc plating after that. Moreover, the 1st steel plate 1 and the 2nd steel plate 2 are each coat | covered with the zinc plating layer. The first steel plate 1 is an example of a first member described in the claims, the second steel plate 2 is an example of a second member, and the galvanized layer is an example of a coating layer.

When welding the 1st steel plate 1 and the 2nd steel plate 2, in order to make the recessed part 3 of the 1st steel plate 1 and the 2nd steel plate 2 oppose as shown in FIG. The flat part 4 of the 2nd steel plate 2 is made to oppose, a force is applied from the direction of the arrow 10, and it adheres and hold | maintains. At this time, the galvanized layer of the first steel plate 1 and the galvanized layer of the second steel plate 2 are in close contact. As a result, a space 5 is formed by the first steel plate 1 and the recess 3 of the second steel plate 2. In the space 5, the gap between the first steel plate 1 and the second steel plate 2 becomes larger from the end toward the center. A region where the first steel plate 1 and the second steel plate 2 are not in close contact with each other and the gap is within the range of the reference value L is a “welding target region”, which is denoted by reference numeral 6. .

Subsequently, in a state where the first steel plate 1 and the flat portion 4 of the second steel plate 2 are held in close contact with each other, the laser is continuously or intermittently welded from the direction of the arrow 7 as shown in FIG. Irradiate the target area 6. The 1st steel plate 1 and the 2nd steel plate 2 become the fusion | melting part 8 partially by laser irradiation, and the plate-shaped member with which the 1st steel plate 1 and the 2nd steel plate 2 were welded is obtained. If at least one of the first steel plate 1 and the second steel plate 2 is a galvanized steel plate, the vapor generated by evaporating the galvanized layer is generated in the space 5 as indicated by an arrow 9. The vapor | steam of the coating which moved and vaporized escapes to the space 5, The pressure is relieved, and a welding defect is suppressed.

The gap reference value L shown in FIG. 2 is preferably 0.05 mm or more and 0.25 mm or less. If the gap is less than 0.05 mm, the vapor evaporated by the galvanized layer cannot be sufficiently released from the welded location, which may cause welding failure. If the gap exceeds 0.25 mm This is because there is a possibility of causing separation of the welded portion, and there is a possibility that the welding strength is insufficient.

間隙 The gap in the welding target area 6 must be strictly managed. In the present embodiment, the recess 3 is formed by pressing, so that the shape can be made uniform. Thereby, it is possible to easily maintain the gap of the welding target region 6 within the range of the reference value L simply by closely holding the first steel plate 1 and the flat portion 4 of the second steel plate 2. In addition, by making the welding position based on the position where the recess 3 is formed, it is possible to weld a region having a strictly controlled gap.

Moreover, since the flat part 4 of the 1st steel plate 1 and the 2nd steel plate 2 is closely_contact | adhered, it is prevented that the 1st steel plate 1 and the 2nd steel plate 2 are thermally deformed by welding. Yes.

4 (a) to 4 (e) are examples of the shape of the projection 3a in a plan view (view A shown in FIG. 1). The planar shape of the concave portion 3 formed together with the convex portion 3a is free as long as a welding target region 6 suitable for welding can be formed between the first steel plate 1 and the second steel plate 2. It is. For example, among the ellipse like the convex part 30, the circle like the convex part 31, the square like the convex part 32, the rectangle like the convex part 33 and the composite shape like the convex part 34, etc. What is necessary is just to select a thing suitable for intensity | strength improvement. Moreover, it is preferable that the space 5 has a volume in which the pressure inside the space 5 does not exceed the reference value due to vapor generated by laser irradiation. The reference value is a pressure at which blowholes and spatter are not generated due to the vapor pressure of the galvanized layer evaporated by welding, and is, for example, 2 atmospheres.

It is preferable to provide the marks 20 to 24 at the centers of the convex portions 30 to 34, respectively. The marks 20 to 24 are provided by laser marking, engraving or press working with a mold. Further, it is preferable that the marks 20 to 24 correspond to the shape of each convex portion. For example, the mark 20 on the elliptical convex portion 30 is elliptical, the mark 21 on the circular convex portion 31 is circular, the mark 22 on the convex portion 32 that is square is a cross, and a vertically long rectangle. The mark 23 on the convex portion 33 can be set to a cross whose length is longer than the horizontal, and the mark 24 on the convex portion 34 having an X shape can be set to an X shape or the like. The marks 20 to 24 make the center position of the convex portion clear, and the shape of the convex portion can be easily identified, which serves as a mark indicating the position and shape when the laser beam is irradiated on the welding target region 6. Further, if the marks 20 to 24 are photographed with a camera and recognized, automatic welding can be performed.

4 (a) to 4 (e), the solid lines represented by the convex portions 30 to 34 represent the end portions of the respective convex portions 30 to 34, and the dotted lines represent the respective concave portions 3 and the first steel plate. 1 represents the position of the region 6 to be welded inside the space 5 formed by 1. The laser irradiates the dotted line part continuously or intermittently.

(Example)
The exterior panels of the elevators used for the elevator doors, platform doors, and car room walls are provided inside the building. For this reason, importance is placed on harmony with the interior of the building, and various exterior appearances are required according to the indoor device. For example, it can be manufactured by various means such as painting a steel plate member or applying a hairline, etching or mirror finish to a stainless steel material. The plate-shaped member described above can be applied to products using the plate-shaped member in addition to the exterior panel of the elevator. Products using plate-like members include self-standing panels such as switchboards and control panels, indoor and outdoor units provided in air conditioning equipment, water heaters, and lighting equipment.

Generally, spot welding, arc welding, or adhesion using an adhesive is used for joining a member whose appearance is mainly a reinforcing material. When the steel plate members are joined using spot welding or arc welding, the distortion, which is caused by welding, is corrected on the member whose appearance is mainly used, and then painted.

When the member whose appearance is the main component is stainless steel, it may be joined by bonding because of the property that distortion is more easily generated by welding than a steel plate member. However, many adhesives are flammable, and there is a risk that the joint may be peeled off in the event of a fire. Therefore, it is necessary to assist the joint by caulking or rivets.

Compared with these joining methods, laser welding makes it possible to obtain a narrow bead and a deep penetration shape due to the steep energy density distribution that is a characteristic of the laser. For this reason, even a thin steel plate can perform high-speed and precise heat input control regardless of a material such as a steel plate member or a stainless steel material. Therefore, there is little heat influence with respect to a to-be-welded member, and an external appearance surface can be welded with low distortion. In addition, laser welding equipment is easy to automate and can be more efficiently welded. Therefore, laser welding is employed.

The laser welding apparatus includes an optical system including a laser oscillator, various mirrors, a condenser lens, etc., a welding head apparatus that moves the laser welding head to a desired position, and the shape, welding position, and state of a member to be welded. The image recognition processing device to be monitored, various sensors such as a temperature sensor and appropriate processing programs and various data are stored, and the laser oscillator and the welding head driving device are controlled based on the recognition result of the image recognition processing device, etc. A control device is provided. These are well known to those skilled in the art or can be appropriately selected from those known.

The laser welding apparatus also has a function of measuring the thickness of a member to be welded and irradiating a laser having an output suitable for the thickness in order to further improve the welding quality.

Next, a method of manufacturing the external panel by laser welding will be described.
As shown in FIG. 5 or FIG. 6, the

outer panel

16 or 17 has the

second steel plate

11 or 13 joined to the first steel plate 15 whose appearance is the main component. The

second steel plate

11 or 13 is a reinforcing material hidden behind the first steel plate 15. The arrangement of the reinforcing material is omitted in the longitudinal direction as shown in FIG.

The convex part 12 is previously formed by press work in the part joined to the 1st steel plate 15 of the

2nd steel plate

11 or 13. FIG. The convex portion 12 has an elliptical shape in plan view, and the side opposite to the first steel plate 15 is the protruding direction. A concave portion is formed on the opposite side of the convex portion 12. A mark 14 representing the center position of the convex portion 12 and the shape of the convex portion is formed at the center of the convex portion 12. The flat part around the concave part formed on the opposite side of the convex part 12 and the flat part of the first steel plate 15 are held in close contact with each other. The laser beam is formed at the end of the space corresponding to the space 5 shown in FIGS. 2 and 3 formed by the concave portion formed on the opposite side of the convex portion 12 and the first steel plate 15 by a laser welding device (not shown). Irradiated. The said edge part is a position where the space | interval between the 1st steel plate 15 and the

2nd steel plate

11 or 13 is 0.05 mm or more and 0.25 mm or less.

When performing automatic welding, as shown in FIG.5 and FIG.6, the

2nd steel plate

11 or 13 is piled up on the 1st steel plate 15, and the flat part of a mutual joint surface is closely_contact | adhered and hold | maintained. Using the mark 14 of the convex portion 12 formed on the

second steel plate

11 or 13 as a reference position, the laser is irradiated continuously or intermittently at a preset speed and locus.

Since the convex portion 12 of the present embodiment is elliptical, the locus of laser irradiation is elliptical, but other shapes such as the convex portions 31 to 34 shown in FIGS. 4A to 4E are used. On the other hand, when welding, the locus | trajectory according to each shape is programmed.

The laser simultaneously melts the

second steel plate

11 or 13 and the first steel plate 15, but does not melt the vicinity of the opposite surface, which is the appearance surface of the first steel plate 15, so that the spot diameter, output, focus And adjust the welding head speed.

When the laser is irradiated, the first steel plate 15 and the

second steel plate

11 or 13 at the irradiated location are melted. The molten part is united, naturally cooled, solidified, and fixed by welding. At this time, since the boiling point (about 900 ° C.) of the galvanized layer is lower than the melting temperature of the steel plate (about 1500 ° C.), the galvanized layer evaporates to become steam. This steam is discharged and stays in the space formed by the concave portion formed on the opposite side of the convex portion 12 and the first steel plate 15 from the welding location.

As in this example, when there is no gap suitable for welding and a space for escaping vapor evaporated from the galvanized layer in the welded portion, the vapor of the galvanized layer remains in the molten steel plate member, It has caused welding defects such as formation or spattering by blowing a part of the steel plate member with the pressure of the steam.

However, as in this embodiment, if there is an appropriate gap in the melted part and a space for escaping the vapor evaporated from the galvanized layer, poor welding due to the vapor evaporated from the galvanized layer does not occur.

Also, the galvanized layer at the welded part is partially removed by laser irradiation. As a result, since the steel plate is exposed, aging corrosion of the part can be considered. However, by performing welding in a vacuum or an inert gas-filled environment, the space 5 shown in FIGS. 2 and 3 is sealed, and the outside air is shut off. Therefore, aging corrosion is prevented. In addition, aging corrosion is prevented by galvanizing the weld bead.

(Modification)
In this embodiment, the first member is the

first steel sheet

1 or 15 having a galvanized layer on both sides as a coating layer, and the second member is a second steel plate having a galvanized layer on both sides as a coating layer. Although the example which is the

steel plates

2, 11, and 13 was demonstrated, any one of the surface which contacts the 2nd member in a 1st member, and the surface which contacts the 1st member in a 2nd member What is necessary is just to have a coating layer in the surface. In this case, even if the coating layer becomes steam, it moves to the inside of the space 5, the pressure is relaxed, and poor welding is suppressed.

Moreover, although the 1st member was the

1st steel plates

1 and 15 and the 2nd member was the

2nd steel plates

2, 11, and 13 in the present Example, the 1st member was demonstrated. The second member may be any member that can be welded, and is not limited to iron, and can be applied to various alloys. The composition, structure, strength, ductility, and the like of the steel plate are not limited.

In the present embodiment, the example in which the coating layer is a galvanized layer has been described. However, the coating layer only needs to have a boiling point lower than the melting points of the first member and the second member. It may be a plating layer plated with metal or a resin layer.

The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. In other words, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

This application is based on Japanese Patent Application No. 2018-032139 filed on Feb. 26, 2018. The specification, claims, and entire drawings of Japanese Patent Application No. 2018-032139 are incorporated herein by reference.

1 1st steel plate, 2nd steel plate, 3 concave portion, 3a convex portion, 4 flat portion, 5 space, 6 weld target area, 8 melted portion, 11 second steel plate, 12 convex portion, 13 second steel plate , 14 mark, 15 1st steel plate, 16 external panel, 17 external panel, 20 mark, 21 mark, 22 mark, 23 mark, 24 mark, 30 convex part, 31 convex part, 32 convex part, 33 convex part, 34 Convex part.

Claims

A method of superposing and welding a first member and a second member,
At least one of the first member and the second member has a coating layer,
The melting point of the first member and the second member is higher than the boiling point of the coating layer,
Holding the flat portion of the first member and the flat portion around the recess formed in the second member in close contact,
Melting a welding target region of the first member and the second member in a space formed by the concave portion and the flat portion of the first member;
Overlap welding method.
Melting the first member and the second member by continuously or intermittently irradiating a laser in accordance with the shape of the welding target region set in the peripheral edge of the space;
The lap welding method according to claim 1.
The space formed by the concave portion and the flat portion of the first member has a volume in which the pressure inside the space does not exceed a reference value due to steam generated by welding.
The lap welding method according to claim 1 or 2.
The reference value is a pressure that does not cause blow holes and spatter in the first member and the second member due to the vapor pressure of the coating layer evaporated by welding,
The lap welding method according to claim 3.
The coating layer is provided on any one of the surface in contact with the second member in the first member and the surface in contact with the first member in the second member.
The lap welding method according to any one of claims 1 to 4.
At least one of the first member and the second member is a steel plate having a galvanized layer as the covering layer.
The lap welding method according to any one of claims 1 to 5.
In the welding target region, a gap between the first member and the second member is 0.05 mm or more and 0.25 mm or less.
The lap welding method according to any one of claims 1 to 6.
The welding is performed in a vacuum or inert gas filled environment,
The lap welding method according to any one of claims 1 to 7.
The first member and the second member;
A plate-like member welded by the lap welding method according to any one of claims 1 to 8.