JPH09123701A - Disc wheel for automobile made of aluminum alloy plate - Google Patents

Abstract

(57) [PROBLEMS] To manufacture a rim and a disc by using an aluminum alloy plate material to reduce the weight of an automobile wheel and to improve the radial load durability of the wheel. A wheel in which an aluminum alloy disc formed of a plate material is fitted to an inner peripheral side of an aluminum alloy rim formed of a plate material and joined by welding, the flange fitting of the disc. There is an inclination angle at the joint, and at least the fitting end is press-fitted into the rim when the rim and the disc are fitted, and there is no pressure or a gap between the rim and the disc at the fitting start end. A wheel for an automobile made of an aluminum alloy plate material, which is joined to a rim by welding in a state of having.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile disc wheel using an aluminum alloy plate material.

[0002]

2. Description of the Related Art Saving fuel consumption by reducing the vehicle weight of an automobile is important not only for reducing the fuel cost of the automobile, but also for maintaining and improving the global environment such as reducing the consumption of fossil fuel. The use of aluminum in automobile disc wheels (hereinafter simply referred to as "wheels") has been studied as a major contributor to weight reduction of automobiles. In particular, weight reduction of wheels greatly reduces the unsprung load of automobiles, and It has been clarified that it is also effective for improvement. Aluminum alloy wheels are already widely used in cast wheels. However, since aluminum alloy castings are inferior in toughness and ductility compared to wrought materials, aluminum alloy casting wheels have to be made thicker, and despite the fact that the specific gravity of aluminum alloys is about 35% that of steel, it is made of steel. Only 15-20% less weight than wheels. Therefore, at present, it cannot be said that the use of aluminum for automobile wheels sufficiently satisfies the demand for weight reduction. The aluminum alloy cast wheels, which are widely used nowadays, have become more important in terms of fashionability rather than being substantially lighter in weight, depending on the tastes of automobile users.

Various studies have been conducted to reduce the weight of an automobile wheel by using an aluminum alloy wrought material excellent in toughness and ductility, especially a plate material. From the viewpoint of strength, corrosion resistance, etc.
The 1-Mg-based alloy or the Al-Mg-Si-based alloy is selected. The rims that make up the wheel have already been put to practical use with such aluminum alloy plate materials.
Many of the disks still use thick castings, and the adoption of wheels that use plate materials for the disks is limited to a part of racing cars and the like.

[0004]

As shown in FIG. 1, a conventional aluminum alloy automobile wheel 40 is generally used.
The aluminum alloy disc 30 is welded to the inside of the aluminum alloy rim 20 on which the tire can be mounted on the outer peripheral surface by molding. The disk 30 is formed by press forming of a plate, forging or cutting of a casting, and a normal hat portion 5 is formed outside the hub mounting surface 3, and the hub mounting surface is for hub mounting. It has a bolt through hole 2 and a hub hole 1. The disc is provided with a flange portion 4 which is a fitting portion with the rim, fitted to the rim, and after being fitted, joined by a welding bead portion 8 by welding at a fitting start end portion 6 of the disc flange portion.

The production of automobile wheels is lighter, stronger,
From the viewpoint of productivity, as in the case of manufacturing a steel disc, an aluminum alloy disc obtained by press-forming a blank of a plate material having a uniform plate thickness is generally preferable. However, when a wheel composed of the aluminum alloy plate disc and the aluminum alloy plate rim thus obtained is subjected to a radial load durability test based on the test method defined in JIS D4103, the weld bead portion or its vicinity is obtained. Fatigue cracks occur in the
There is a problem that the durability specified in S is not satisfied.
On the other hand, if the amount of deposited metal in the weld bead is increased to improve the strength of the weld bead, the heat input to the weld increases and the rim and disc materials near the weld bead are affected by excessive heat. There is the problem that the material softens and the overall strength of the wheel is not improved as intended.

In the manufacture of conventional automobile disc wheels, when assembling the rim and the disc with a steel plate wheel, the formed rim and the disc are fitted to each other, and the fitting ends of the rim and the disc are melt-welded, or A general method is to join the flange part of the disk with resistance spot welding. Further, in the conventional method, the fitting portions of the rim and the disc flange portion are molded and fitted so as to be parallel to each other. Even if a wheel made of an aluminum alloy plate is manufactured by a method similar to the method of manufacturing a wheel using such a steel plate and a radial load durability test is performed, durability comparable to that of the steel plate wheel cannot be obtained. . In addition, there is a problem that durability (fluctuation) is large and sufficient reliability cannot be obtained even for wheels intended to be manufactured under the same conditions. In the case of aluminum alloy plate wheels, considering that the rigidity and strength of the aluminum alloy plate material is different from that of the steel plate, the thickness of the aluminum alloy plate to be used is increased to compensate for these differences. An alloy plate hole was made and tested, but it did not solve the problem.

For example, by molding using a thick material and cutting the thickness of the portion that can be tolerated for strength to reduce the weight, or attaching a reinforcing component to the insufficient strength portion of the disk by welding or the like. Countermeasures may be considered, but these methods require extra materials that reduce the yield or extra manufacturing man-hours, and it is possible to achieve both sufficient weight reduction effect and economic efficiency by adopting aluminum alloy plate material. Absent.

[0008]

DISCLOSURE OF THE INVENTION As a result of examining the stress generation condition of each part of the disk under the conventional radial load endurance test condition of the conventional wheel, the present inventor found that the stress in the radial direction is increased in the conventional wheel shape and mounting state. Is applied, the load distribution of the stress on the weld bead is large, and it was found that sufficient durability in the radial load test could not be obtained, and the disk shape and rim to reduce the stress load on the weld bead were obtained. The present invention has been completed by earnestly researching the method of assembling the disc and the disc. That is, the present invention is a wheel in which an aluminum alloy disc formed of a plate material is fitted to an inner peripheral side of an aluminum alloy rim formed of a plate material and joined by welding. Is there an angle of inclination in the flange fitting part, and when the rim and the disk are fitted, at least the fitting end part is press-fitted into the rim, and there is no pressure between the rim and the disk at the fitting start end part. Alternatively, the aluminum alloy plate-made automobile wheel is characterized in that it is joined to the rim by welding while having a gap.

[0009]

DETAILED DESCRIPTION OF THE INVENTION When a wheel is subjected to a radial load, stress is transmitted through the tire to the rim and then to the disc. At this time, if the pressure for fitting the rim and the disc is weak or if the fitting is not perfect, the load of the stress transmitted from the rim to the disc at the weld becomes large and cracks occur at or near the weld bead. Easier to do. In addition to such structural factors of the wheel, aluminum alloy has a smaller elastic modulus than steel plate, the weld bead has a cast structure and weak mechanical properties, and it is used as a material for rim and disc. Is 5000 or 600
Although 0 series alloy aluminum alloy plates are used, these alloys have drawbacks such as inevitability of softening due to welding heat input. The present invention has found a measure for avoiding such an unavoidable property of an aluminum alloy as a drawback of a material for an aluminum alloy wheel, and realizes weight reduction of the wheel by using aluminum.

The details of the present invention will be described in more detail with reference to FIG. FIG. 2 shows a typical example of the fitted state of the rim 20 and the disk 30 with a partial cross section of the fitted portion.
The disc 30 has a flange portion 4, and when the disc 30 is fitted to the rim 20, the disc is press-fitted from a tip portion 6 (hereinafter referred to as a disc fitting start end portion) of the disc to start fitting. As the fitting progresses, the other end 7 of the flange portion of the disc (hereinafter referred to as the disc fitting end portion)
Is pressed into a predetermined position and the fitting is completed. FIG.
2A and 2B show the fitted state of the present invention. , FIG. 2
FIG. 2A is an example in which the present invention is applied to a wheel 40 corresponding to a conventional wheel, but FIG. 2B shows another embodiment of the present invention in which the disc flange portion 4 is made longer than a conventional general wheel. Thus, the present invention is applied to a wheel having a large fitting portion, and the work of fitting the shape of the flange portion 4 and fitting work are facilitated. FIG. 2C shows a fitting state (although it is difficult to show the degree of fitting on the drawing) when the fitting margin is less than 0.1, and FIG. 2D shows the disk 30 or If the circularity of the rim 20 is not sufficient and there is still a gap between the rim 20 and the fitting end portion 7 of the disc 30 even after the fitting, or the fitting portion is different from the present invention, the fitting starting end portion 6 of the disc is This is the case where the press-fitted state is reached. Figure 2 (D)
In the case of, the stress transmitted from the rim 20 to the disc 30 is passed through the weld bead portion 8 which is a connecting portion between the rim 20 and the disc 30 and the vicinity of the weld bead portion 8 which exerts a stress on the weld bead portion 8. The stress applied to the weld bead portion 8 is large. Therefore, the weld bead portion 8 having weak strength or the weld heat affected zone in the vicinity of the weld bead portion 8 where softening occurs receives external stress. Therefore, the durability is reduced.

In the case of FIG. 2C, as shown in FIG.
The weld bead portion 8 or the vicinity thereof is not subjected to particularly strong stress, but the stress is evenly applied to the flange portion 4 and the weld bead portion 8 of the disk 30, and the weld bead must be a weak portion in terms of strength. The stress load on the portion 8 cannot be reduced.

On the other hand, the method of the present invention shown in FIG.
The method of (A) and FIG. 2 (B) is from the rim 20 to the disc 3
Most of the stress transmitted to zero is the rim 20 and the disk 30.
Is transmitted through the fitting end portion or the area in the vicinity of the fitting end portion and there is a gap between the rim and the disk at or near the welding bead portion 8, so that the stress on the welding bead portion 8 is significantly reduced. That is, the stress transmitted from the rim 20 will be received at the fitting end portion 7 of the disc farthest from the weld bead portion 8 and in the vicinity thereof. Further, since there is a gap between the rim 20 and the disc 30 in the vicinity of the weld bead portion 8, the rim 20 and the disc 30 can generate distortion or slip in the gap, respectively.
The stress directly applied to the weld bead portion 8 can be relaxed.

In order to obtain the full effect of the present invention, FIG.
As shown in FIGS. 2A and 2B, when the disc 30 is mounted on the rim 20, the disc flange portion 4 extends from the fitting end portion 7 to the fitting start end portion 6 of the disc flange portion 4 to the center axis of the wheel. An inclination angle Θ (hereinafter referred to as a disc fitting surface angle Θ) is provided. Furthermore, the disc 30 and the rim 20 must be fitted tightly together.

The disc fitting surface angle Θ is preferably 0.5 to 5 degrees. If the disc fitting surface angle Θ is less than 0.5 degrees, considering the circularity of the disc 30 and the rim 20 and the fitting workability, there is no great difference in shape as compared with the prior art, and a remarkable effect cannot be obtained. Further, when the disc fitting surface angle Θ exceeds 5 degrees, the gap between the rim 20 and the fitting starting end portion 6 of the disc 30 becomes excessively large. In order to avoid stress concentration due to welding, it is desirable to make the shape of the transition portion from the disc fitting start end portion 6 to the weld bead portion 8 smooth, but if this gap becomes too large, in order to smooth this shape. Requires a large amount of deposited metal, and accordingly, the heat input for welding becomes excessive and the materials of the rim 20 and the disk 30 in the heat-affected zone of welding are apt to soften, which is not preferable.

Next, the fitting margin between the rim 20 and the disk 30 is preferably 0.1 to 0.5%. Mating allowance is 0.
If it is less than 1%, the effect of improving the radial load durability is not remarkable, and if it exceeds 0.5%, the effect is saturated and the work of fitting becomes difficult. Here, the fitting margin refers to a value represented by the following equation. Mating allowance = (outer diameter of disc mating part-inner diameter of rim mating part) /
(Inner diameter of rim fitting part) x 100 (%)

[0016]

Embodiments of the present invention will be described below with reference to the drawings. A disk wheel 40 for automobiles having a wheel size of 5.5JJ × 13 shown in FIG. 1 (dimension: diameter 329.4)
The rim 20 and the disk 30 each having a width of 140 mm and a width of 140 mm were prepared using an aluminum alloy plate JIS 5454 alloy rolled plate. As the rim 20, a plate material having a plate thickness of 4.4 mm was roll-formed into a hoop, flash butt-welded into an annular shape, and then formed using a rotary rim forming roll. Rim 2
The formation of 0 may be performed by roll forming, or by any method used for forming a rim of a plate material such as spinning forming and press forming.

The disk 30 is manufactured by press molding using a rolled plate having a plate thickness of 6.3 mm. In this embodiment, the outer peripheral portion of the flange of the disk is turned, and as shown in Table 1, the disk fitting surface angle Θ is set. Finished to a specified angle. The rim and the disk thus obtained are fitted together using a press, and
The rim and the disc were welded by MIG full circumference welding as shown in FIG. The leg length of the weld bead 8 was set to about the plate thickness of the disc so that no step was formed at the transition part from the fitting start end part 6 of the disc to the weld beat part 8. Regarding the aluminum alloy plate wheel thus obtained, JIS
A radial load durability test was performed under a load condition of 1598 kg based on the automobile wheel test method specified in D4103. Table 1 shows the test results. The numbers in Table 1 show the service life until cracking is recognized in the radial load durability test. This test result shows that the life can be improved by increasing the fitting allowance even with the conventional disk shape, but by further providing the disk fitting surface angle Θ, the life can be more significantly improved. Also,
The weight of each aluminum alloy plate wheel manufactured in this example is 3.5 kg, and the weight of each steel plate wheel having the same size is 6.5 kg. Therefore, according to the method of the present invention, the aluminum alloy plate wheel achieves a weight reduction of 45% as compared with the steel plate wheel.

[0018]

[Table 1]

[0019]

As is clear from the above examples, the present invention has the effect of significantly improving the life of the radial load endurance test by using a plate material having a uniform thickness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional automobile wheel.

FIG. 2 is a partial cross-sectional view showing a fitting portion between a rim and a disc of an automobile wheel showing an embodiment of the present invention and a conventional example.

[Brief description of reference numerals]

 1 hub hole 2 bolt through hole 3 hub mounting surface 4 disc flange portion 5 hat portion 6 disc fitting start portion 7 disc fitting end portion 8 weld bead portion 20 rim 30 disc 40 wheel Θ disc fitting surface angle

Claims (1)

[Claims] 1. A wheel in which an aluminum alloy disc formed of a plate material is fitted to an inner peripheral side of an aluminum alloy rim formed of a plate material and joined by welding. Is there an angle of inclination in the flange fitting part, and when the rim and the disk are fitted, at least the fitting end part is press-fitted into the rim, and there is no pressure between the rim and the disk at the fitting start end part. Alternatively, a disc wheel for an automobile made of an aluminum alloy plate material, which is joined to a rim by welding while having a gap.