JP2001340988A - Lap joint and its welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lap joint part and its welding method capable of improving connection strength in a shearing direction and a bending direction, and also having stable connection quality. SOLUTION: In a lap welded joint, a first part 1 and second part 2 formed by metallic materials respectively are overlapped each other. The overlapped portion is then irradiated for welding by a source of welding heat (for example, high density energy like arc, laser, electron beam and the like) from the surface of the first part 1. A groove 2a is beforehand formed on the surface of the second part 2 in which the first part 1 is overlapped. The groove 2a covering a full length of a connected portion is formed along a welding direction, and also has a V-shape in section. As compared with conventional cases of welding by arranging the groove 2a in the second part 2 as described in the above and by a prior method, this welding method is capable of improving connecting strength (shearing strength and bending strength) so that a connecting area of the connected portion is increased more than that of the prior method, as melted metal is poured into the groove 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lap joint part and a method for welding the same.

[0002]

2. Description of the Related Art In recent years, there has been a demand for miniaturization and high performance of parts, and accordingly, there has been an increase in highly reliable welding of materials having high crack sensitivity in limited space where joining needs are limited. Conventionally, as a method of welding a material having high crack susceptibility, a lap joint welding as shown in FIG. 5 has been known, and a first material formed of a material having good weldability (a material having low crack susceptibility) on the upper side. A part 100 is combined with a second part 110 made of a material having poor weldability (a material having high crack susceptibility) on the lower side, and a penetration amount of a material (the second part 110) that is easily cracked by controlling the penetration depth is controlled. (Dilution ratio) (see FIG. 6).

[0003]

However, in the above method, when the welding area is increased by increasing the output of the welding heat source in order to improve the joining strength, the penetration amount of the easily crackable material (the second part 110) is increased. Therefore, the safety zone (safety zone) for cracks is narrowed, and there is a limit in achieving both prevention of cracks and improvement in joint strength. In addition, structurally, with respect to the stress in the bending direction, a sufficient strength cannot be ensured only by the joint area UP when the size of the component is reduced due to the limited space.

Further, in ordinary welding, it is possible to improve the strength in the shearing direction by increasing the number of welding points, but the strength in the bending direction does not have a proportional relationship with the increase in the area. Can not expect. The present invention has been made based on the above circumstances, and an object of the present invention is to provide a lap joint part capable of improving the joint strength in the shear direction and the bending direction and obtaining a stable joint quality and a method for welding the same. It is in.

[0005]

(Means for Solving the Problems) A first part and a second part made of a metal material are overlapped with each other,
A lap joint part obtained by irradiating a welding heat source from above the surface of the first part to melt-weld the first part and the second part, wherein a groove is provided in advance in a portion to be joined of the second part. The first component and the second component are joined with the metal melted by the irradiation of the welding heat source flowing into the groove. In this lap joint part, the joining area increases due to the flow of the molten metal into the groove, and the joining effect in the shear direction and the bending direction is increased by adding the shape effect (anchor effect and caulking effect) of the joint. Can be improved and stable joining quality can be obtained.

(Means of Claim 2) In the lap joint part according to claim 1, the second part is made of a metal material having higher crack sensitivity than the first part. In this case, by providing a groove in advance in the second component made of a material that is more easily broken than the first component, the amount of dilution of the second component can be suppressed, so that there is an effect that cracking can be prevented. .

(Means of Claim 3) A first material made of a metal material
A welding method in which the first component and the second component are overlapped with each other, and the first component and the second component are melt-welded by irradiating a welding heat source from above the surface of the first component. Is characterized in that fusion welding is performed in a state where a groove is provided in advance in the portion to be joined. According to this welding method, the joining area is increased by the molten metal flowing into the groove, and the joining effect in the shear direction and the bending direction is increased by adding the shape effect (anchor effect and caulking effect) of the joint. Can be improved and stable joining quality can be obtained.

(Means of Claim 4) In the welding method according to Claim 3, the second component is made of a metal material having higher crack susceptibility than the first component. In this case, the first
By providing grooves in advance in the second component made of a material that is more likely to be cracked than in the first component, the amount of dilution of the second component can be suppressed, so that there is an effect that cracking can be prevented.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a process chart of lap joint welding. In the lap joint welding of the present embodiment, the first component 1 and the second component 2 made of a metal material are overlapped,
The overlapping portion is irradiated with a welding heat source from above the surface of the first component 1. As the welding heat source, for example, high-density energy such as an arc, a laser, and an electron beam is used.

The first part 1 and the second part 2 constituting the lap joint part of the present invention have a part shape according to the use such as a plate shape or a cylindrical shape as shown in FIG. 1, for example. , In the thickness direction. However, the second component 2 has a groove 2a in advance on the surface to be overlapped with the first component 1.
Are formed. The groove 2a is formed over the entire length of the portion to be joined and along the welding direction, and is provided, for example, in a V-shaped cross section.

[0011] As described above, the case where welding is performed by providing the groove 2a in the second part 2 in advance, and the conventional method (the second part 2)
2 (a) and 2 (b), the molten metal flows into the groove 2a in this method (b), as shown in FIGS. 2 (a) and 2 (b). Was found to be larger than that of the conventional method (a). FIGS. 2A and 2B are schematic diagrams of the vicinity of the bonding interface. In addition, as a result of measuring the shear strength of the joint, as shown in FIG. 3, a value higher by about 25% was obtained in the same joint area as compared with the case where welding was performed by the conventional method. As shown in the graph of FIG. 3, the relationship between the bonding area and the bonding strength generally shows that the bonding strength tends to increase with the increase of the bonding area.
As shown in (c), when the molten metal flows into the groove 2a, it is considered that the anchor effect and the caulking effect due to the contraction of the molten metal promote the strength increase.

Further, even when a material having high crack sensitivity is used for the second component 2, the groove 2a is provided in the second component 2 and the second component 2 is welded to dissolve the amount of the easily crackable material (dilution amount).
The safety zone against cracking (safety zone) can be expanded to twice or more than before, and the soundness of the metallographic structure due to the suppression of the amount of dilution,
The toughness is improved.

[0013] Further, when the penetration shape of the joint is compared with that of the conventional method, as shown in FIG.
Each time the irradiation point of the welding heat source shifts, a notch (a black point shown in the figure) becomes a starting point of stress concentration. In this method, as shown in FIG. 4B, molten metal flows into the groove 2a. This eliminates the notch in the joint, and improves the resistance to stress. As an example of experimental data,
When the groove 2a was provided in the second component 2 to increase the bonding area by 12%, the shear strength was improved by 27% and the bending strength was improved by 40%.

(Effects of the present embodiment) According to the welding method of the present embodiment, compared with the conventional method, the joining area is increased and the shape effect (anchor effect and caulking effect) of the joint is obtained. By being obtained, the joining strength in the shear direction and the bending direction can be improved. Further, when a material having high crack susceptibility is placed on the lower side (the second part in this embodiment) with respect to the irradiation direction of the welding heat source and welding is performed, a groove is formed in the second part in advance, so that the crack is formed. Since the dilution ratio of the material which is easy to suppress can be suppressed, there is an effect that cracks at the joint can be prevented.

[Brief description of the drawings]

FIG. 1 is a process chart of lap joint welding.

FIG. 2A is a schematic view showing the vicinity of a bonding interface according to the conventional method, FIG. 2B is a schematic view showing the vicinity of a bonding interface according to the present method,
(C) It is sectional drawing of the joining part by this method.

FIG. 3 is a characteristic diagram showing a relationship between a bonding area and a bonding strength.

FIG. 4A is a schematic diagram showing the vicinity of a bonding interface according to a conventional method, and FIG. 4B is a schematic diagram showing the vicinity of a bonding interface according to the present method.

FIG. 5 is a process chart of lap joint welding (prior art).

6A is a cross-sectional view of a joint, and FIG. 6B is an explanatory diagram of a dilution ratio.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st component 2 2nd component 2a Groove

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norio Tanaka 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Yoshiki Kariya 1-1-1, Showa-cho, Kariya-shi, Aichi Co., Ltd. Inside DENSO (72) Inventor Kenji Uchiyama 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (Reference) 4E001 AA03 BB12 QA02 4E066 AB04 CA11 4E068 BA01 BF00 DB01

Claims (4)

[Claims] A first component and a second component made of a metal material are superimposed on each other, and a welding heat source is irradiated from above the surface of the first component to separate the first component and the second component. A lap joint part which is fusion-welded, wherein a groove is provided in advance in a portion to be joined of the second part,
A lap joint component, wherein the first component and the second component are joined in a state where the metal melted by the irradiation of the welding heat source flows into the groove. 2. The lap joint component according to claim 1, wherein the second component is made of a metal material having a higher susceptibility to cracking than the first component. . 3. A first component and a second component made of a metal material are superimposed on each other, and a welding heat source is irradiated from above the surface of the first component to separate the first component and the second component. A welding method for performing fusion welding, wherein the fusion welding is performed in a state where a groove is provided in advance in a portion to be joined of the second component. 4. The welding method according to claim 3, wherein the second component is made of a metal material having a higher susceptibility to cracking than the first component.