JP-7857063-B2 - Single-sided spot welding method

Inventors

• 木許 圭一郎
• 藤本 和広
• 西村 直樹
• 渡瀬 雄貴

Assignees

• ダイハツ工業株式会社

Dates

Publication Date

20260512

Application Date

20231106

Claims (1)

1. In a one-sided spot welding method in which a planned joining portion, located near the edge of the first metal plate, is applied to the overlapping portion of a first metal plate and a second metal plate by applying current while pressing the portion with an electrode only from the second metal plate side, A one-sided spot welding method in which, of the first metal plate, a plurality of beads extending in directions that intersect each other are provided in the region opposite to the edge with respect to the planned joining portion.

Description

This invention relates to a single-sided spot welding method. Direct spot welding is a commonly used spot welding method, where the overlapping portion of multiple metal plates is sandwiched between a pair of electrodes and current is applied. However, as shown in Figure 6, if the planned joining portion P, located at the overlapping portion 103 of the lower plate 101 and the upper plate 102, is covered by a metal plate 104 with a hat-shaped cross-section, the planned joining portion P cannot be sandwiched between the pair of electrodes 110 and 120. For example, as shown in Figure 7, if a through hole 105 is formed in the metal plate 104 with a hat-shaped cross-section, and electrode 120 is inserted through this through hole 105, the planned joining portion P can be sandwiched between the pair of electrodes 110 and 120 from both sides in the thickness direction. However, forming a through hole 105 in the metal plate 104 with a hat-shaped cross-section reduces the rigidity of the metal plate 104, necessitating increased thickness or the use of high-strength materials, leading to higher costs. Therefore, when welding such areas, "one-sided spot welding," in which an electrode is pressed against the area to be joined from only one side in the thickness direction and current is applied, is sometimes used (see, for example, Patent Document 1). Specifically, as shown in Figure 8, the area to be joined P is pressed from above with a welding electrode 130, and a ground electrode 140 is in contact with another part of the workpiece. Current is then applied between the two electrodes 130 and 140 to weld the area to be joined P. Japanese Patent Publication No. 2023-139742 This is a plan view of a workpiece to which a one-sided spot welding method according to one embodiment of the present invention is applied.This is a cross-sectional view in the X direction along the line II-II in Figure 1.This is a cross-sectional view in the X direction along the line III-III in Figure 1.This is a cross-sectional view in the Y direction along the line IV-IV in Figure 1.This is a cross-sectional view in the Y direction along the line V-V in Figure 1.This is a cross-sectional view of a workpiece having a metal plate with a hat-shaped cross-section.This is a cross-sectional view showing how direct spot welding is performed on a metal plate with a hat-shaped cross-section by creating through holes.This is a cross-sectional view showing the process of indirect spot welding being performed on a workpiece having a metal plate with a hat-shaped cross-section.This is an enlarged cross-sectional view of the overlapping portion of the lower and upper plates in Figure 8 when pressed with an electrode. The embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows a lower plate 1 as a first metal plate and an upper plate 2 (shown as a dotted line in Figure 1) as a second metal plate, which constitute a part of the car body (lower back). Joining portions P1 and P2 are provided at the overlapping portion between the lower plate 1 and the upper plate 2. In the illustrated example, the width W of the overlapping portion (the distance between the edge 1a of the lower plate 1 and the edge 2a of the upper plate 2) is small, and the joining portions P1 and P2 are provided near the edge 1a of the lower plate 1 and the edge 2a of the upper plate 2. Note that the upper plate 2 is the metal plate that the welding electrode 10 (see Figure 2) contacts, and the lower plate 1 is the metal plate that the welding electrode 10 does not contact, and this is not intended to limit the orientation of these metal plates when they are assembled to the car body. Furthermore, in the following explanation, the direction along the edge 1a of the lower plate 1 is referred to as the X direction, and the direction along the surface of the lower plate 1 that is approximately perpendicular to the edge 1a, specifically the longitudinal direction of the surface of the lower plate 1 where the planned joining portions P1 and P2 are provided, is referred to as the Y direction (see Figure 1). As shown in Figure 2, a third metal plate 3 is provided below the planned joining portions P1 and P2, with a space Q in between. Since the third metal plate 3 does not have through holes for inserting electrodes, it is not possible to bring electrodes into contact with the planned joining portions P1 and P2 from below. As a welding method for these planned joining portions P1 and P2, indirect spot welding, as one embodiment of the one-sided spot welding method according to the present invention, is applied. On the lower plate 1, a bead is provided in the region opposite the edge 1a in the Y direction relative to the planned joining portions P1 and P2 (in Figure 1, the region to the lower left of the planned joining portions P1 and P2) (see Figure 1). A bead is an elongated convex portion (a concave portion when viewed from the opposite side) forme