JPH05329671A - Manufacture of loading wheel - Google Patents

Abstract

PURPOSE:To manufacture a loading wheel having a high fatigue strength by joining a rim and a disk by laser welding or electron beam welding. CONSTITUTION:Whole the circumference or a part of each of the rim and the disk are superpose welded or fillet-welded so as to make the product of the joining width W(mm) and the overall length of joining part L(mm) suffices Formula, I. (WXL)/Fr>=30.1... (I). It the Formula, Fr is a load in the radial direction (kgf) in the radial direction loading durability test stipulated by JISD4103.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a road wheel having high fatigue strength, which is obtained by welding a rim and a disk by laser welding or electron beam welding.

[0002]

2. Description of the Related Art Conventionally, when a road wheel is assembled by joining a disc and a rim, joining is performed by spot welding. FIG. 3 is a schematic view of the manufacturing process of the road wheel, in which the disc 4 (see (b)) is pressed into the rim 8
It is fitted to (Fig. (E)) (Fig. (F)), and the fitting portion A is joined by spot welding to form a road wheel. Disk 4
Is made by press forming the material 1 ((a)
The figure), the rim 8 is produced by butt welding (DC butt welding) the material 5 and press-molding ((c) figure and (d) figure).

This road wheel is an important part for maintaining safety while the automobile is running, and its welded portion is subjected to repeated load during which one revolution of the axle makes one cycle, so that the fatigue strength is high. Is required, which is one of the most important items in road wheel specifications.

In the road wheel assembled by spot welding as described above, a fatigue crack is likely to occur from the interface between the weld metal and the base metal, and this crack propagates to the rim side, but at this stage the crack is visually detected. Because it is possible, it does not lead to a minute air leak.

By the way, recently, a method of joining the above-mentioned fitting portion of the disc and the rim by laser welding has been studied (Autotech 1991 Proceedings, Jikkaihei 2-114186).
(See the official gazette). This is because laser welding has a smaller thermal deformation than spot welding and requires less welding margin, so that the dimensional accuracy of the road wheel can be improved and the weight can be reduced. Since the amount of heat input is extremely small in this laser welding as compared with other welding methods, the welded portion undergoes rapid heating and quenching. As a result, the metal structure of the welded part becomes a fine and high-strength structure, and the tensile residual stress is reduced, which is advantageous from the viewpoint of ensuring high fatigue strength and can be said to be a promising technology in the future. Although it cannot be carried out in the atmosphere like this laser welding, electron beam welding has a small amount of heat input, and it is possible to obtain a high-strength welded portion similarly to laser welding.

[0006]

The road wheel assembled by laser welding has various advantages as described above, but its fatigue characteristics are not always clear, and particularly in laser welding, high fatigue strength is obtained. However, since the bead width is narrow, it is a major issue to ensure further reliability against fatigue.

In general, the fatigue life of the welded material correlates with the area of the welded joint, and the larger the joint area, the longer the fatigue life. Therefore, in the case of spot welding, the fatigue life can be estimated by the number of welding points, but in laser welding there are no appropriate guidelines, and rational design methods for joint width, bead length, etc. have not been established. .

The present invention has been made to solve the above problems, and when the road wheel is assembled by welding and joining the rim and the disk by laser welding or electron beam welding, the width of the joint and the length of the weld bead are set. It is an object of the present invention to provide a method for manufacturing a road wheel having high fatigue strength by defining conditions such as the above.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention prototyped a load wheel in which various combinations of a joint width W and a weld bead length L when a rim and a disk are joined by laser welding were manufactured. As a result of repeating the radial load endurance test specified in JIS D 4103 and repeating the examination, the fatigue life is (W ×
It was found to have a strong correlation with the value of L) / F _r .
Note that F _r is the radial load in the radial load durability test specified in JIS D 4103.

Since the present invention has been made based on this fact, the gist thereof lies in the following method of manufacturing a road wheel.

A method of manufacturing a road wheel in which a rim and a disk are welded and joined by laser welding or electron beam welding, wherein a product of a joining width W and a total length L of the joining portion is as follows (1)
A method for manufacturing a road wheel, characterized in that the rim and the disc are entirely or partially welded by lap welding or fillet welding so as to satisfy the formula.

(W × L) / F _r ≧ 0.1 (1) where W: joint width (mm) L: total length of joint (mm) F _r : radial load specified in JIS D 4103 Radial Load (kgf) in Durability Test FIG. 1 is an enlarged view of the joint portion A in FIG. 3 (f) and is a view for explaining welding conditions defined in the present invention. (a) is the case of lap welding, (b) is the case of fillet welding, and W in the figure is the joint width. Although the total length L of the joint is not shown,
If the rim and the entire circumference of the disc are welded, the entire circumference is also
When the rim and a part of the disc are welded, the total length of the welded part is L.

[0013]

In the following, the reason why the welding conditions are set as described above when the rim and the disk are lap-welded by laser welding or electron beam welding to manufacture a road wheel will be described.

FIG. 2 shows that a disc and a rim produced by using a steel sheet (thickness 3.8 mm) having the same chemical composition as the hot-rolled steel sheet used in Examples described later are fitted to each other, and the joint width W and the total length of the joint portion are It is a figure which shows the result of having performed the radial load endurance test prescribed | regulated to JIS D 4103 about the road wheel joined by laser welding (lap welding) while changing L. Radial load F
_r is the maximum load Q determined by JIS D 4103 according to the shape of the rim. Tire pressure was 2.5 kgf / cm ² , wheel nut tightening torque was 12 kgf · m, and if the rim and disc were separated or the tire leaked air, it was considered as fatigue fracture.

As shown in FIG. 2, a good correlation is recognized between the fatigue life (rotation speed) and (W × L) / F _r .
The specified number of rotations (life) shown in JIS D 4103 is 400,000, and by setting (W × L) / F _r ≧ 0.1 from the figure, we will manufacture a road wheel with the same life as conventional products. It turns out that it is possible.

FIG. 2 shows the results for the case of lap welding, but similar results can be obtained for the case of fillet welding.

In addition to welding the rim and the disc all around, various lengths of the bead can be used, such as 4 places at equal intervals (4 weld beads), 6 places at equal intervals (6 also). When the combination was welded and an endurance test was performed, it was confirmed that the fatigue life did not depend on the number of welded portions, but was substantially dependent only on the total length L of the joint.

When the road wheel is manufactured, the step of welding and joining the rim and the disk is performed by laser welding or electron beam welding under the above-mentioned conditions, whereby the road wheel having high fatigue strength can be manufactured. .. It should be noted that when welding and joining are performed by simultaneously irradiating a plurality of laser beams or electron beams to perform welding, the cycle time can be shortened and the production efficiency can be increased.

[0019]

EXAMPLE A disc and a rim were produced using a hot-rolled steel sheet having a thickness of 3.8 mm and having the chemical composition and mechanical properties shown in Table 1, and after fitting them, the fitting portion Was laser-welded, and a tire of 195/65 R 15 90S specified in JIS D 4202 was prototyped, and a fatigue test was performed to measure the fatigue life.

The disk is manufactured by pressing the test material into a predetermined shape, and the rim is manufactured by reducing the thickness of the test material from 3.8 mm to 2.6 mm and then DC butt welding. , By pressing into a predetermined shape.

Laser welding uses a 5 kw carbon dioxide laser oscillator to produce a beam focused by a lens with a focal length of 254 mm.
He gas was sprayed at 30 liters per minute while irradiating from the rim side, and welding was performed while rotating the wheel intermittently.

The fatigue test is carried out by the radial load endurance test specified in JIS D 4103, and the tire air pressure is 2.5 kgf.
/ cm ² , wheel nut tightening torque 12kgf ・ m,
The maximum load (fatigue strength) at which the number of rotations reached the specified number of rotations of 400,000 was determined. If the rim and the disc separate, or if the tire leaks air, it is considered to be fatigue fracture.

The measurement results are shown in Table 2. In addition, (W in the table
In the column of × L) / F _r , the value obtained with F _r of 1350 kgf is shown. This value is 195/65 R 15 used for the test.
Maximum load defined for 90S tires (600 kg
Similarly, the coefficient (2.
25), and if the fatigue strength required in the above test is 1350 kgf or more, the specifications are satisfied,
Means good.

In this table, No. 1 to No. 9 are examples of lap welding, No. 10 to No. 13 are fillet welding, and No. 14 is an example of spot welding performed for comparison. No.1 to No.4, N
For o.6 to No.8, No.10 and No.12, (W × L) /
The value of F _r satisfies the condition defined in the present invention, and the fatigue strength is 1350 kgf or more regardless of the welded portion.
Good results have been obtained. On the other hand, No. 5 and No.
In all of Nos. 9, No. 11 and No. 13, the value of (W × L) / F _r was less than 0.1, and the fatigue strength was less than 1350 kgf.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

By assembling the road wheel by joining the disc and the rim by laser welding, by applying the method of the present invention, a road wheel with high fatigue strength can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram for explaining welding conditions defined by the present invention.

FIG. 2 Radial load F in radial load endurance test
It is a figure which shows the ratio of the product of the joint width W (mm) with respect to _r (kgf), and the total length L (mm) of a junction part, ie, (W * L) / _Fr, and a fatigue life.

FIG. 3 is a schematic view of a manufacturing process of a road wheel.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Sotoyama 4-533 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Masato Kurita, 4-chome Kitahama, Chuo-ku, Osaka City, Osaka Prefecture 5-33 Sumitomo Metal Industries, Ltd. (72) Hideya Kamahori, 2 Takaramachi, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Satoshi Nishigaki 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Address: Nissan Motor Co., Ltd. (72) Inventor: Etsuo Isaka 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Nissan Motor Co., Ltd.

Claims (1)

[Claims] 1. A method of manufacturing a road wheel in which a rim and a disk are welded and joined by laser welding or electron beam welding, wherein a product of a joint width W and a total length L of the joint is as follows (1).
A method for manufacturing a road wheel, characterized in that the rim and the disc are entirely or partially welded by lap welding or fillet welding so as to satisfy the formula. (W × L) / F _r ≧ 0.1 (1) where W: joint width (mm) L: total length of joint (mm) F _r : radial load endurance test specified in JIS D 4103 Radial load (kgf)