JP7733435B2 - Welding member and manufacturing method thereof, and manufacturing method of welded structure - Google Patents

Description

The present invention relates to welding components and manufacturing methods thereof, as well as methods for manufacturing welded structures.

Welded structures are used in various fields, including civil engineering and construction. For example, T-joints, in which steel sections or steel pipes are welded to a base plate, are used as column base hardware.
Arc welding is a commonly used welding method, but if structural steel or steel pipes are butted against the base plate and directly welded (main welding), thermal deformation will occur, causing the components to shift at the weld surface and reducing the dimensional accuracy of the column base hardware.

Therefore, Patent Document 1 proposes a method for fabricating a frame structure (welded structure) by butting frame elements together in the form of a T-joint and welding them together, in which extremely small joining protrusions are formed in advance so as to be evenly spaced on the end faces of specific frame elements that will be butted against the mating frame element, and the frame elements are temporarily attached together by projection welding using these joining protrusions, and then the butted portions of the frame elements are actually welded together. This method makes it possible to prevent thermal deformation during actual welding.
However, the method described in Patent Document 1 is prone to gaps between the components due to insufficient penetration of the protrusions or residual molten material during projection welding (tack welding), and it is difficult to remove these gaps during main welding. This causes deviations in the butt angle, resulting in reduced dimensional accuracy of the frame structure after main welding.

On the other hand, as a method for improving the dimensional accuracy between welding parts in projection welding, Patent Document 2 proposes a projection welding method in which a recess is formed in at least one of the peripheral edge of the base of the welding projection of one welding part having a welding projection and the portion of the other welding part facing the welding projection, and the portion melted during welding is accommodated in the recess.
However, the method described in Patent Document 2 requires forming a welding protrusion on one of the welding members and a recess on its periphery, or forming a welding protrusion on one of the welding members and a recess on the other welding member, respectively, which requires a lot of work for the forming process and also has the problem of wasting material in the portion removed during the forming process.

Japanese Patent Application Laid-Open No. 2004-344942 Japanese Patent Application Laid-Open No. 2003-48074

The present invention has been made to solve the above-mentioned problems, and aims to provide a welding component and a manufacturing method thereof that can be temporarily attached without gaps by projection welding, improve dimensional accuracy after main welding, have high productivity, and reduce material waste.
Another object of the present invention is to provide a method for manufacturing a welded structure that has high dimensional accuracy and productivity and that can reduce material waste.

The inventors conducted extensive research to solve the above problems and discovered that by forming a point-symmetric uneven structure when cutting a single piece of material to form a welding surface, the cut surface would have a structure suitable for temporary welding using projection welding, leading to the completion of this invention.

That is, the present invention relates to a manufacturing method for a welding component that cuts one material to form a welding surface for two components, wherein the welding surface has one or more point-symmetric uneven structures, and the welding component is used for temporary attachment by projection welding.
The present invention also relates to a method for manufacturing a welded structure, in which the welding surface of the welding member is brought into contact with a member to be welded and temporarily attached by projection welding, and then the welding member and the member to be welded are actually welded together.
Furthermore, the present invention relates to a welding component used for temporary attachment by projection welding, wherein the welding surface has one or more point-symmetric uneven structures, and the point-symmetric uneven structures are point-symmetric structures with the center of symmetry being the center of the uneven structures when the welding surface is viewed from the side.

According to the present invention, it is possible to provide a welding component and a manufacturing method thereof that can temporarily attach the components without gaps by projection welding, improve dimensional accuracy after main welding, have high productivity, and reduce material waste.
Furthermore, according to the present invention, it is possible to provide a method for manufacturing a welded structure that has high dimensional accuracy and productivity and is capable of reducing waste of material.

1 is a conceptual diagram for explaining a method for manufacturing a welding member according to an embodiment of the present invention. 10 is an example of an uneven structure formed on a welding surface. FIG. 1 is a conceptual diagram for explaining projection welding.

Embodiments of the present invention are described in detail below. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements to the following embodiments, as appropriate and based on the common knowledge of those skilled in the art, fall within the scope of the present invention, provided that they do not deviate from the spirit of the present invention.

<Welding member and manufacturing method thereof>
FIG. 1 is a conceptual diagram for explaining a method for manufacturing a welding member according to an embodiment of the present invention.
As shown in FIG. 1( a), one material 10 is prepared. Next, as shown in FIGS. 1( b) and 1(c), the material 10 is cut at a cutting portion 11 to form welding surfaces 21 a, 21 b of two members 20 a, 20 b. The cutting is performed so that the welding surfaces 21 a, 21 b have one or more point-symmetric uneven structures 22 a, 22 b. By cutting in this manner, the welding surfaces 21 a, 21 b of the two members 20 a, 20 b suitable for temporary attachment by projection welding can be formed in a single cut, thereby increasing productivity and reducing material waste.

The material 10 is not particularly limited as long as it is a material that can be used for projection welding. For example, a steel material, an alloy material, etc. may be used. The surface of the material 10 may also be plated with various platings.
The shape of the material 10 may be selected appropriately depending on the type of welded structure to be fabricated, and is not particularly limited. For example, when fabricating a column base metal for a T-joint, various shapes such as a groove shape, a chevron shape, an H-shape, an I-shape, an L-shape, a Z-shape, and a pipe shape can be used.

The cutting direction of the material 10 may be appropriately selected depending on the type of welded structure to be fabricated, and is not particularly limited. For example, when manufacturing a column base metal for a T-joint using a channel steel, the material 10 may be cut in a direction perpendicular to the axial direction of the channel steel, and the cut surfaces may be used as the welding surfaces 21 a, 21 b.
There are no particular limitations on the method for cutting the material 10 as long as it is a method that can cut the material 10 into a desired shape. For example, cutting methods using a press, gas, plasma, laser, water jet, etc. can be used.

When viewed from the side of the cut portion 11, the uneven structures 22a and 22b formed by cutting have a point-symmetric structure with the center of symmetry being the center of the uneven structures 22a and 22b. By using this structure, the height and width of the convex portions and the depth and width of the concave portions in the uneven structures 22a and 22b can be made the same.

The shapes of the concave-convex structures 22 a, 22 b are not particularly limited as long as they have a point-symmetric structure. For example, the shapes of the convex portions of the concave-convex structures 22 a, 22 b on a plane perpendicular to the welding surfaces 21 a, 21 b (a plane on which the concave-convex structures 22 a, 22 b are visible) may be triangular, rectangular, semicircular, or the like.
Here, examples of shapes other than the concave-convex structures 22 a and 22 b shown in Fig. 1 are shown in Fig. 2. As shown in Fig. 2, the concave-convex structures 22 a and 22 b can be a point-symmetric shape of a right triangle (Fig. 2(a)), a point-symmetric shape of a semicircle (Fig. 2(b)), a point-symmetric shape of a rectangle (Fig. 2(c)), or the like.

The width of the convex portions of the uneven structures 22a and 22b is preferably 1.5 to 2.5 mm, more preferably 1.6 to 2.4 mm, even more preferably 1.7 to 2.3 mm, and most preferably 1.8 to 2.2 mm. The height of the convex portions is preferably 0.5 to 1.5 mm, more preferably 0.6 to 1.4 mm, even more preferably 0.7 to 1.3 mm, and most preferably 0.8 to 1.2 mm. By controlling the width and height of the convex portions within the above ranges, the welding strength achieved by projection welding can be improved.

The members 20a and 20b manufactured as described above are used for temporary attachment by projection welding.
As an example, a conceptual diagram for explaining tack welding by projection welding using the member 20a is shown in FIG.
As shown in FIG. 3( a), projection welding is performed by contacting the welding surface 21 a of the member 20 a with the workpiece 30 and applying pressure while passing an electric current between the member 20 a and the workpiece 30. In projection welding, as shown in FIG. 3( b), resistance heat generated by passing an electric current melts the convex portions of the uneven structure 22 a of the member 20 a and the periphery of the workpiece 30 where the convex portions are in contact. This molten portion 40 then flows into the concave portions 20 of the uneven structure 22 a of the member 20 a. Therefore, the entire welding surface 21 a of the member 20 a is more likely to adhere to the workpiece 30, making it less likely for gaps to form between the member 20 a and the workpiece 30. This prevents gaps from remaining between the member 20 a and the workpiece 30 during final welding, improving dimensional accuracy after final welding.

Projection welding can be performed using commercially available equipment. The conditions for projection welding are not particularly limited and can be adjusted depending on the equipment used and the type of material 10. A typical projection welding process involves a pressure of 10 to 30 kN, a current of 10 to 40 kA, and a current flow time of 100 to 200 ms.

<Method of manufacturing a welded structure>
In a method for manufacturing a welded structure according to an embodiment of the present invention, the welding surface of the welding member is brought into contact with the workpieces to be welded and temporarily attached by projection welding, and then the welding member and the workpieces are permanently welded together.
By performing tack welding using the above welding components by projection welding, gaps are less likely to occur between the welding components and the welded components, thereby improving dimensional accuracy. Furthermore, when tack welding is performed by arc welding or the like, a weld bead remains, which gets in the way during main welding and makes the main welding unstable. However, by using projection welding, there is no weld bead, allowing for stable and satisfactory main welding.

When manufacturing a T-joint column base hardware as a welded structure, for example, a channel steel is cut in a direction perpendicular to its axial direction, and the cut surface is used as the welding surface.Then, the base plate of the welded member is abutted in the form of a T-joint and temporarily attached by projection welding.
The conditions for tack welding by projection welding are not particularly limited, and the welding can be performed in accordance with the above description of projection welding.

The welding method is not particularly limited, and methods known in the relevant technical field can be used. For example, arc welding, laser welding, and laser-arc hybrid welding can be used for the welding. Among these, laser welding and laser-arc hybrid welding can perform welding well, for example, because welding can be performed from the outside of a channel steel to the inside.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples in any way.

Example 1
A steel material was cut to form a welding surface (cut surface) having a right-angled triangular point-symmetrical uneven structure as shown in Fig. 2(a), where the width of the protrusions was set to 2.0 mm and the height of the protrusions was set to 1.1 mm.
Next, the welding surface of the welding member obtained above was brought into contact with a steel base plate of a welded member in the form of a T-joint, and projection welding was performed to obtain a test piece. The projection welding was performed under conditions of a pressure of 14 kN, a current of 26 kA, and a current flow time of 150 ms.

(Comparative Example 1)
A welding member was obtained in the same manner as in Example 1, except that the steel material was cut to form a welding surface (cut surface) having a convex portion. The convex portion had a width of 2.0 mm and a height of 1.1 mm.
Next, the welding members obtained above were used to carry out projection welding under the same conditions as in Example 1 to obtain test pieces.

The test pieces obtained in the above examples and comparative examples were evaluated for gaps in the welded portions.
The presence or absence of gaps in the welded portions was visually observed. As a result, no gaps were found in Example 1, but gaps were found in Comparative Example 1.

As can be seen from the above results, the present invention provides a method for manufacturing welded components that allows for gap-free temporary welding using projection welding, improves dimensional accuracy after main welding, has high productivity, and reduces material waste. The present invention also provides a method for manufacturing welded structures that has high dimensional accuracy and productivity, and reduces material waste.

REFERENCE SIGNS LIST 10 Material 11 Cut portion 20a, 20b Member 21a, 21b Welding surface 22a, 22b Concave-convex structure 30 Member to be welded 40 Melted portion

Claims (6)

A method for manufacturing a welding component for cutting one material to form a welding surface for two components, comprising:
The welding surface has one or more point-symmetric uneven structures,
The method for manufacturing a member to be welded, wherein the member to be welded is used for temporary attachment by projection welding. The method for manufacturing a welding component according to claim 1, wherein the shape of the convex portions of the uneven structure on a plane perpendicular to the welding surface is triangular, rectangular, or semicircular. The method for manufacturing a welding component according to claim 1 or 2, wherein the material is a channel steel and is cut in a direction perpendicular to the axial direction of the channel steel. A method for manufacturing a welding component according to any one of claims 1 to 3, wherein the convex portions of the uneven structure on a surface perpendicular to the welding surface have a width of 1.5 to 2.5 mm and a height of 0.5 to 1.5 mm. A method for manufacturing a welded structure, in which the welding surface of a welding component manufactured by the manufacturing method for welding components described in any one of claims 1 to 4 is brought into contact with a workpiece and temporarily attached by projection welding, and then the welding component and the workpiece are permanently welded together. A welding member used for temporary attachment by projection welding,
A welding component having a welding surface having one or more point-symmetric uneven structures, the point-symmetric uneven structures being a point-symmetric structure with the center of symmetry being the center of the uneven structure when the welding surface is viewed from the side.