JPWO2019163949A1 - Superposition welding method and plate-shaped member - Google Patents

Abstract

The flat first steel plate (1) and the flat portion (4) of the second steel plate (2) having the recess (3) formed are held in close contact with each other. At least one of the first steel plate (1) and the second steel plate (2) has a galvanized layer. The melting points of the first steel plate (1) and the second steel plate (2) are higher than the boiling points of the galvanized layer. In the space (5) formed by the recess (3) and the first steel plate (1), the first steel plate (1) and the second steel plate (2) are not in close contact with each other, and the gap is welded. The area suitable for welding is irradiated with a laser and welded. The vaporized coating vapor generated by welding is released to the space (5).

Description

The present invention relates to a superposition welding method and a plate-shaped member.

Galvanized steel sheets, which are widely used for structural members, building materials, etc., are superposed, and the superposed portion is irradiated with a laser and welded. The boiling point of zinc used in a galvanized steel sheet is about 900 ° C., and the melting point of a steel sheet as a base material is about 1500 ° C. Therefore, when the galvanized steel sheet is heated to a temperature exceeding the melting point of the steel sheet in order to weld it, zinc is vaporized into steam. When this steam stays in the welded portion, 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 kind of phenomenon occurs not only in galvanized steel sheets but also in the case of welding a metal member having a coating layer having a boiling point lower than the melting point of the base metal.

For this reason, measures have been taken to allow steam whose coating has been vaporized by welding to escape from the welded portion. Generally, a spacer, a jig, or the like is used to provide a gap between the overlapping members so that steam can escape from the gap.
Further, 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 fitted into the recess to form a gap between the two galvanized steel sheets. , A method of letting zinc vapor escape from this gap to the outside is disclosed.

Japanese Unexamined Patent Publication No. 2013-237053

However, if a spacer, a jig, or the like is used to provide a gap between the members to be superposed and welded, the cost increases and it is difficult to maintain the gap, so that it is difficult to maintain the quality of welding. Further, since there is a gap between the members, it is easy to tolerate the deformation of the members due to the heat of welding, and there is a problem that high quality welding cannot be obtained.

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

The present invention has been made in view of the above circumstances, and even if at least one of the members is required to be flat, the member can be prevented from being deformed by steam generated by heat during welding. It is an object of the present invention to provide a high quality welding method and a plate-like member.

In order to achieve the above object, the method of superimposing and welding the first member and the second member according to the present invention has 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. However, in the space formed by the concave portion and the flat portion of the first member, the welding target region of the first member and the second member is melted.

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

Cross-sectional view of each steel plate welded by the welding method according to the embodiment of the present invention. Cross-sectional view of a steel sheet in a state of being in close contact and held, which is one of the steps of the welding method according to the embodiment of the present invention. Cross-sectional view of a steel sheet in a welded state, which is one of the steps of the welding method according to the embodiment of the present invention. (A) to (e) are plan views illustrating recesses formed in a steel sheet by the welding method according to the embodiment of the present invention. Perspective view of the exterior panel welded by the welding method according to the embodiment of the present invention. Perspective view of the exterior panel welded by the welding method according to the embodiment of the present invention.

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

In the present embodiment, it is assumed that the member to be superposed and welded is a steel plate, and both sides are substantially covered with zinc plating. This is called a galvanized steel sheet, and is obtained by coating the surface of an iron plate base material mainly composed of iron 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 arranged 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, by pressing. The concave portion 3 shown in FIG. 1 is accompanied by a convex portion 3a, but only the concave portion 3 may be formed without the convex portion 3a. It is also possible to form the recess 3 in the steel sheet by cutting and then coat it with zinc plating. Further, the first steel plate 1 and the second steel plate 2 are each coated with a zinc-plated layer. The first steel plate 1 is an example of the 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 first steel plate 1 and the second steel plate 2, as shown in FIG. 2, in order to make the recess 3 of the first steel plate 1 and the second steel plate 2 face each other, the first steel plate 1 and the first steel plate 1 are welded. The flat portion 4 of the second steel plate 2 is opposed to the flat portion 4, and a force is applied from the direction of the arrow 10 to bring them into close contact with each other. 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 with each other. As a result, the space 5 is formed by the recess 3 of the first steel plate 1 and the second steel plate 2. In the space 5, the gap between the first steel plate 1 and the second steel plate 2 increases from the end portion toward the center portion. The 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 and is suitable for welding is the "welding target region", which is indicated by reference numeral 6. ..

Subsequently, with the flat portion 4 of the first steel plate 1 and the second steel plate 2 in close contact and held, the laser is welded continuously or intermittently from the direction of arrow 7 as shown in FIG. Irradiate the target area 6. By irradiating the laser, the first steel plate 1 and the second steel plate 2 are partially formed as a molten portion 8, and a plate-shaped member in which the first steel plate 1 and the second steel plate 2 are 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 the galvanized layer from the first steel plate 1 and the second steel plate 2 evaporates inside the space 5 as shown by an arrow 9. The vapor of the moving and vaporized coating escapes to the space 5, so that the pressure is relieved and welding defects are suppressed.

The reference value L of the gap 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 vaporized by the galvanized layer cannot be sufficiently released from the welded part, which may cause welding defects. If the gap exceeds 0.25 mm, it may occur. This is because it may cause separation of the welded portion and the welding strength may be insufficient.

The gap in the welding target area 6 needs to be strictly controlled. In the present embodiment, since the recess 3 is formed by press working, the shape can be made uniform. As a result, the gap in the welding target region 6 can be easily maintained within the range of the reference value L simply by holding the flat portion 4 of the first steel plate 1 and the second steel plate 2 in close contact with each other. By referring to the position where the recess 3 is formed as the welding position, it is possible to weld a region having a strictly controlled gap.

Further, since the flat portion 4 of the first steel plate 1 and the second steel plate 2 is held in close contact with each other, it is possible to prevent the first steel plate 1 and the second steel plate 2 from being thermally deformed by welding. There is.

4 (a) to 4 (e) are examples of the plan view (view A view shown in FIG. 1) of the convex portion 3a. The concave portion 3 formed together with the convex portion 3a has a free planar shape 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. Is. For example, among an ellipse such as a convex portion 30, a circle such as a convex portion 31, a square such as a convex portion 32, a rectangle such as a convex portion 33, and a composite shape such as a convex portion 34, the purpose thereof is, for example. The one suitable for improving the strength may be selected. Further, 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 the steam generated by the laser irradiation. The reference value is a pressure at which blow holes and sputtering are not generated due to the pressure of the vapor of the galvanized layer evaporated by welding, for example, 2 atm.

It is preferable to provide marks 20 to 24 at the centers of the above-mentioned convex portions 30 to 34, respectively. The marks 20 to 24 are provided by laser marking, engraving, press working with a die, or the like. Further, it is preferable that the marks 20 to 24 correspond to the shape of each convex portion. For example, the mark 20 of the elliptical convex portion 30 is an elliptical shape, the mark 21 of the circular convex portion 31 is a circular shape, and the mark 22 of the square convex portion 32 is a cross having the same length and width, and a vertically long rectangle. The mark 23 of the convex portion 33 can be set to a cross whose length is longer than the width, and the mark 24 of the convex portion 34 having an X shape can be set to an X shape or the like. The marks 20 to 24 clarify the center position of the convex portion, and the shape of the convex portion can be easily discriminated, and serve as a mark indicating the position and shape when irradiating the welding target region 6 with the laser. Further, if the marks 20 to 24 are photographed with a camera and the image is recognized, automatic welding can be performed.

The solid lines shown in the convex portions 30 to 34 shown in FIGS. 4A to 4E represent the ends of the convex portions 30 to 34, and the dotted lines represent the concave portions 3 and the first steel plate. It represents the position of the welding target area 6 inside the space 5 formed by 1 and 1. The laser irradiates this dotted line portion continuously or intermittently.

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

In general, spot welding, arc welding, or adhesive bonding is used to join the member whose appearance is the main component and the reinforcing material. When the steel plate members are joined by spot welding or arc welding, the strain mainly generated by the appearance is corrected by using a grinder or the like, and then painted.

When the member whose main appearance is mainly made of stainless steel, it may be joined by adhesive because it is more likely to be distorted by welding than the steel plate member. However, many adhesives are flammable and may peel off in the event of a fire. Therefore, it is necessary to assist the bonding by caulking or rivets.

Compared to these joining methods, laser welding can obtain narrow beads and deep penetration shapes due to the steep energy density distribution that is characteristic of lasers. From this, even if it is a thin steel plate, high-speed and precise heat input control can be performed regardless of the material such as the steel plate member or the stainless steel material. Therefore, the heat effect on the member to be welded is small, and the appearance surface can be welded with low distortion. In addition, since laser welding equipment is easy to automate, welding can be performed more efficiently, so laser welding is adopted.

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

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

Next, a method of manufacturing the appearance panel by welding with a laser will be described.
In the appearance panel 16 or 17, as shown in FIG. 5 or 6, a second steel plate 11 or 13 is joined to the first steel plate 15 whose main appearance is the main body. The second steel plate 11 or 13 is a reinforcing material hidden behind the first steel plate 15. As for the arrangement of the reinforcing material, in addition to the reinforcement in the longitudinal direction as shown in the figure, the reinforcing material may be arranged in the lateral direction, but it is omitted.

A convex portion 12 is formed in advance by press working on a portion of the second steel plate 11 or 13 to be joined to the first steel plate 15. The convex portion 12 has an elliptical shape in a 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. At the center of the convex portion 12, a mark 14 indicating the center position of the convex portion 12 and the shape of the convex portion 12 is formed. The flat portion around the concave portion formed on the opposite side of the convex portion 12 and the flat portion of the first steel plate 15 are held in close contact with each other. A laser is placed at the end of a 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 apparatus (not shown). Be irradiated. The end portion is a position where the distance between the first steel plate 15 and the second steel plate 11 or 13 is 0.05 mm or more and 0.25 mm or less.

When automatic welding is performed, as shown in FIGS. 5 and 6, the second steel plate 11 or 13 is superposed on the first steel plate 15, and the flat portions of the joint surfaces are held in close contact with each other. With the mark 14 of the convex portion 12 formed on the second steel plate 11 or 13 as a reference position, the laser is continuously or intermittently irradiated at a preset speed and locus.

Since the convex portion 12 of this embodiment has an elliptical shape, the locus for irradiating the laser has an elliptical shape, but other shapes such as the convex portions 31 to 34 shown in FIGS. 4A to 4E. On the other hand, when welding, a trajectory is programmed according to each shape.

The laser melts the second steel plate 11 or 13 and the first steel plate 15 at the same time, but the spot diameter, output, and focus are not melted near the surface on the opposite side, which is the appearance surface of the first steel plate 15. 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 portion are melted. The molten part is integrated, 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 (about 1500 ° C.) of the steel sheet, the galvanized layer evaporates into steam. This steam is released from the welded portion into the space formed by the concave portion formed on the opposite side of the convex portion 12 and the first steel plate 15 and stays there.

As in this embodiment, when there is no gap suitable for welding and a space for the vaporized steam of the zinc-plated layer to escape in the welded portion, the steam of the zinc-plated layer remains in the molten steel plate member and creates a blow hole. Welding defects were caused, such as forming or blowing off a part of the steel sheet member by the pressure of the steam to generate spatter.

However, as in this embodiment, if there is an appropriate gap in the molten portion and a space for the vaporized steam of the galvanized layer to escape, welding defects due to the vaporized steam of the galvanized layer do not occur.

In addition, the galvanized layer at the welded portion is partially removed by laser irradiation. As a result, since the steel plate is exposed, aged corrosion at that location is considered. However, by performing welding in a vacuum or an environment filled with an inert gas, the space 5 shown in FIGS. 2 and 3 is sealed and the outside air is blocked. Therefore, aging corrosion is prevented. In addition, galvanized coating is applied to the weld bead to prevent aging corrosion.

(Modification example)
In this embodiment, the first member is the first steel sheets 1 and 15 having zinc-plated layers on both sides as a coating layer, and the second member is a second steel sheet having zinc-plated layers on both sides as a coating layer. Although the examples of the steel plates 2, 11 and 13 have been described, any one of a surface of the first member in contact with the second member and a surface of the second member in contact with the first member A coating layer may be provided on 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 welding defects are suppressed.

Further, in the present embodiment, an example in which the first member is the first steel plates 1 and 15 and the second member is the second steel plates 2, 11 and 13 has been described, but the first member The second member may be a weldable member, and is not limited to iron, and can be applied to various alloys, etc., regardless of the composition, structure, strength, ductility, etc. of the steel sheet.

Further, in this embodiment, an example in which the coating layer is a galvanized layer has been described, but the coating layer may have a boiling point lower than the melting point of the first member and the second member, and is other than zinc. It may be a metal-plated plating layer or a resin layer.

The present invention allows for various embodiments and modifications without departing from the broad spirit and scope of the present invention. Moreover, the above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is indicated by the scope of claims, not by the embodiment. Then, various modifications made within the scope of the claims and the equivalent meaning of the 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 February 26, 2018. The specification, claims, and the entire drawing of Japanese Patent Application No. 2018-032139 shall be incorporated into this specification as a reference.

1 1st steel plate, 2nd steel plate, 3 concave part, 3a convex part, 4 flat part, 5 space, 6 welding target area, 8 fused part, 11 second steel plate, 12 convex part, 13 second steel plate , 14 mark, 15 first steel plate, 16 exterior panel, 17 exterior 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.

In order to achieve the above object, in the method of superimposing and welding the first member and the second member according to the present invention, at least one of the first member and the second member has 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, in the space formed by the recess and the flat portion of the first member, the area to be welded having a gap between the first member and the second member is melted to seal the space .

Claims (9)

It is a method of superimposing and welding the first member and the second member.
At least one of the first member and the second member has a coating layer.
The melting points of the first member and the second member are higher than the boiling point of the coating layer.
The flat portion of the first member and the flat portion around the recess formed in the second member are closely held and held.
The weld target region 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.
Superposition welding method. The first member and the second member are melted by irradiating the laser continuously or intermittently according to the shape of the welding target region set on the peripheral edge of the space.
The superposition welding method according to claim 1. The space formed by the recess and the flat portion of the first member has a volume in which the pressure inside the space does not exceed the reference value due to the steam generated by welding.
The superposition welding method according to claim 1 or 2. The reference value is a pressure at which blow holes and sputtering are not generated in the first member and the second member due to the pressure of the vapor of the coating layer evaporated by welding.
The superposition welding method according to claim 3. The coating layer is provided on any one of the surface of the first member that contacts the second member and the surface of the second member that contacts the first member.
The superposition 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 sheet having a zinc-plated layer as the coating layer.
The superposition welding method according to any one of claims 1 to 5. In the welding target region, the gap between the first member and the second member is 0.05 mm or more and 0.25 mm or less.
The superposition welding method according to any one of claims 1 to 6. The welding is performed in a vacuum or an environment filled with an inert gas.
The superposition welding method according to any one of claims 1 to 7. The first member and the second member are provided.
A plate-shaped member welded by the superposition welding method according to any one of claims 1 to 8.

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