JP3238660B2 - Laser welding method for carbon steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding technique for, for example, a vehicle wheel.

[0002]

2. Description of the Related Art Conventionally, as a welding technique for a vehicle wheel, the present applicant has proposed a laser welding method as disclosed in Japanese Patent Application No. 8-28358. This method reduces the number of processing steps and consolidates the process. For example, when joining a vehicle wheel consisting of four parts, rim, spoke, hub, and boss, rim and spoke, spoke and hub, hub and boss Are welded by laser welding which is less affected by thermal distortion and the like.

[0003]

However, for parts such as rims, spokes, hubs, etc., rolled steel sheets having a low carbon content are used to improve workability.
The boss that is easily subjected to direct force from the axle etc. is made of hard carbon steel for machine structural use, which has a higher carbon content than rolled steel sheet. Irradiation of the laser beam in the vertical direction causes a problem that a hardened layer is easily formed in the welded portion.

That is, as shown in FIG. 4, a cylindrical boss 51 is fitted to a hub 52, and as shown in FIG. If the ends of the 51 are fused so as to be melted, a hardened layer c may be generated at the welded portion y as shown in FIG.

[0005] This is because when laser is irradiated on the steel side having a relatively high carbon content, the laser welding is rapidly heated and rapidly cooled. It is considered that a portion having a low carbon content is generated, and a portion having a high carbon content remains as the cured layer c.

Accordingly, an object of the present invention is to homogenize a welded portion and improve welding quality when laser welding different carbon steels having different carbon contents such as the hub and the boss.

[0007]

In order to solve the above-mentioned problems, a welding method according to a first aspect of the present invention provides a welding method for a vehicle wheel.
And laser welding the hub and the hub, wherein the boss and
Both hubs are made of carbon steel and have a pressure
The rolled steel sheet contains more carbon than the carbon steel for machine structural use that constitutes the boss.
Less weight, after inserting the boss into the fitting hole of the hub,
The fitting hole of the hub is increased so that the penetration amount of the hub is increased.
Irradiate the laser from the end face side of the
It was configured to shoot.

[0008] As described above, by irradiating the laser in the oblique direction to the joint surface from the side of the carbon steel having a low carbon content, the ends of the carbon steel having a low carbon content are fused so that the filler wire and the like are fused. Even if not used, the shape of the welded portion can be smoothed, and the carbon component is widely dispersed to homogenize the welded portion, thereby preventing the formation of a hardened layer.

[0009] A welding method according to a second aspect of the present invention is a method for welding a vehicle.
This is a method of laser welding the boss and spoke of the eel.
Therefore, if both the boss and the spoke are made of carbon steel,
Rolled steel plate that mainly constitutes the spoke is a machine that constitutes the boss
The spokes have a lower carbon content than structural carbon steel.
After the boss is inserted into the fitting hole of
So as to increase the number of spokes on the end face side of the fitting hole and
Laser irradiation from the oblique direction to the joint surface
Was.

[0010]

[0011]

[0012]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a plan view of a vehicle wheel to which the welding method of the present invention is applied, FIG. 2 is a longitudinal sectional view of the same, and FIG. 3 is an explanatory view of a laser welding method according to the present invention.

[0013] The laser welding method of the present invention is a technique for preventing the formation of a hardened layer in a welded portion and increasing the joining strength when laser welding different carbon steels having different carbon contents. Specifically, the present invention is applied to welding of a vehicle wheel 1 as shown in FIGS.

That is, the vehicle wheel 1 has a boss 2 through which the wheel shaft is inserted, a hub 3 having a fitting hole to be fitted in the boss 2, and a fitting hole to be fitted in the hub 3. A spoke 4 having a substantially triangular plate shape and the spoke 4
The boss 2 and the hub 3, the hub 3, the spokes 4, and the spokes 4 and the rim 5 are all joined by laser welding.

Of these components, the boss 2 is, for example, J
It is formed by forging a carbon steel for machine structural use such as IS symbol S20C, and has a carbon content of about 0.18 to 0.23%.

The hub 3, the spokes 4, and the rim 5 are all formed by press forming or rim forming a rolled steel sheet represented by JIS symbols such as SPC, SPH, SPAH, etc., and have a carbon content of 0.08-0. .12%.

A problem when laser welding each component is joining of carbon steels having different carbon contents. That is, welding of the joint between the boss 2 and the hub 3 is performed. When a laser is irradiated to the joint from the direction shown by the broken line in FIG. 2, the weld y is hardened as shown in FIG. The formation of the layer c is as described above.

Therefore, in the present invention, laser is irradiated from the direction shown by the solid line in FIG. 2 to weld all the joints along, for example, the circumferential direction. That is, as shown in the enlarged view of FIG. 3 (A), laser is irradiated obliquely from the hub 3 side to the joint surface, and welding is performed so that the end of the hub 3 is melted.

Then, as shown in FIG. 2B, the end of the hub 3 and a part of the boss 2 are melted and fused, so that the welded portion y can be formed into a smooth shape without using a filler wire or the like. And the occurrence of a cured layer can be prevented.

When the laser is irradiated from the side of the hub 3 having a low carbon content, the homogenization of the fusion metal in the welded portion y is promoted, the ductility is suppressed, and the followability to the shrinkage strain at the time of solidification is improved. .

Further, in the case of a three-part vehicle wheel (not shown), the present invention is applied to a joint between a boss and a spoke, and a laser is applied obliquely from the spoke side to fuse the spoke ends. If this is the case, the formation of a cured layer can be similarly prevented.

Although the above description has been made taking the case of a vehicle foil as an example, the laser welding method of the present invention can be applied not only to bonding of a vehicle foil, but also to dissimilar carbon steels having generally different carbon contents. It can also be applied to welding with each other, and by irradiating the laser from the carbon steel side with a low carbon content to the joint surface in an oblique direction and welding, it is possible to prevent the formation of a hardened layer and improve the welding quality .

[0023]

As described above, in the laser welding method of the present invention, when joining different kinds of carbon steels having different carbon contents, the laser irradiation direction is changed from the carbon steel side having a low carbon content to the joint surface. Since the irradiation is performed in an oblique direction, the shape of the welded portion can be made smooth without using a filler wire or the like, and the formation of a hardened layer can be prevented to achieve homogenization. And such a laser welding method,
If the invention is applied to the joining of the hub and the boss or the spoke and the boss of the vehicle foil, the welding quality of the vehicle foil can be improved, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a vehicle wheel to which a welding method according to the present invention is applied.

FIG. 2 is a longitudinal sectional view of the same.

FIG. 3 is an explanatory view of a laser welding method according to the present invention.

FIG. 4 is an explanatory diagram for explaining a defect of the laser welding method.

[Explanation of symbols]

1: Wheel, 2: Boss, 3: Hub, 4: Spoke, 5
... rim, c ... hardened layer, y ... weld.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 26/00 B60B 3/04 B60B 3/10

Claims (2)

(57) [Claims] 1. A method for laser welding a boss and a hub of a vehicle wheel, wherein the boss and the hub are both made of carbon steel, and a rolled steel plate constituting the hub is made of carbon steel for machine structure constituting the boss. The carbon content is also low, and after inserting the boss into the fitting hole of the hub, so that the amount of penetration of the hub increases, from the end face side of the fitting hole of the hub and obliquely to the joining surface. A method for welding a vehicle wheel, comprising irradiating a laser. 2. A boss and a spoke of a vehicle wheel.
Laser welding, wherein the boss and the spoke are not used.
Rolled steel that is also made of carbon steel and forms spokes
The plate has a higher carbon content than the carbon steel for machine structure that constitutes the boss
Less, after inserting a boss into the fitting hole of the spoke,
In front of the spokes, so that the spokes have more penetration
At the end face side of the fitting hole and obliquely with respect to the joint face,
Welding of vehicle wheels characterized by irradiating a laser
Method.