JP2000108602A - Light alloy wheel rim - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of concavity at a welded part, which occurs on an outside surface of a rim due to being drawn in by molten metal (filling) swelling into a hollow section when flash butt welding both ends of an annually bent material, without a large weight increase. SOLUTION: On this wheel rim, projecting parts 5a and 5b with a thickness t3 and t4 which are 2 to 3 times of a standard thickness t1, are formed on a bead seat part 3 and a bead seat opposite part 6 at roughly the center part in the width direction of a hollow section 5. In such a case, the projecting parts 5a and 5b have top parts (i) and (h) positioned so as to face each other and consists of flat surfaces with specified lengths 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light alloy wheel rim mainly used for motorcycles, and more particularly to a light alloy made of a light alloy having a hollow cross-sectional shape formed by bending a shape member into an annular shape and joining both ends by welding. For wheel rims.

[0002]

2. Description of the Related Art Generally, a rim made of a light alloy is formed by winding a shape having a predetermined cross-sectional shape with a roll, bending it into an annular shape, and joining both ends thereof by flash butt welding. The cross-sectional shape of the rim has a well portion recessed in the inner diameter direction in the center, a bead seat portion serving as a tire mounting surface is formed on the left and right sides thereof, and a flange portion is further formed outside the well portion. A hollow portion is formed on the inner diameter side of the seat portion to maintain sufficient strength and reduce the weight.

[0003] The hollow portion is formed along a bead sheet portion having a predetermined width, has a long shape in the width direction, and bulges due to upset during flash butt welding.
The corner is formed by an arc surface so that the extruded burrs do not interfere.

[0004]

When flash butt welding both ends of the above-mentioned annularly curved mold, if the amount of burrs bulging into the hollow portion is small, the molten metal (meat) bulging into the hollow portion is drawn into the hollow portion. In rare cases, a depression may form on the outer surface of the rim. The recessed portion remains as an ecbo-shaped recess (scratch) even after the welding burrs on the outer surface of the rim are shaved by a grinder or the like and further finished with a feather cloth or the like, and cannot be shipped as a product.

The depression of the welded portion can be prevented by increasing the thickness of the periphery of the hollow portion. However, increasing the thickness of the rim increases the weight.

Accordingly, an object of the present invention is to provide a wheel rim made of a light alloy in which the collapse of a welded portion is eliminated without a large increase in weight.

[0007]

According to a first aspect of the present invention, an annularly curved light alloy mold material is formed by joining both ends by welding, and is provided on the inner diameter side of the bead seat portion (3).
In a light alloy wheel rim (1) having a hollow portion (5) that is long in the width direction, at least the bead seat opposite portion (6) at a substantially central portion in the width direction of the hollow portion (5), on the hollow portion side. The thickness of the opposite part (t ₁ ) is 1.3 to 2
A wheel rim made of a light alloy, characterized in that a projection having twice the thickness (t ₄ ) is formed.

According to a second aspect of the present invention, the bead seat opposite portion (6) is provided on the hollow portion side of the bead seat portion (3) at a substantially central portion in the width direction of the hollow portion (5). The light alloy wheel rim according to claim 1, wherein the projection (5a) is formed so as to face the projection (5b).

According to a third aspect of the present invention, the projection (5b
Or 5a, or 5b and 5a) is the top (i,
3. The light alloy wheel rim according to claim ₁ , wherein h) comprises a flat surface having a predetermined length (l ₁ , l ₂ ).

[Operation] Based on the above structure, the hollow part (5)
Is configured to be long in the width direction, and when the upset pressing amount at the time of welding is small, the central portion in the width direction is drawn into the molten metal bulging inward in the hollow portion, and the recessed portion (1) is formed on the outer surface of the rim.
1a and 11b) are likely to occur, but the protrusions (5b, or 5b and 5a) are formed in the portion, and the thickness (t ₄ , t ₃ ) is larger than the surrounding reference thickness (t ₁ ). 1.3 to 2.0 times, reduces the influence on the rim outer surface due to the molten metal bulging in the hollow part during the welding, and prevents the occurrence of a concave portion due to the depression on the outer surface I do.

Note that the reference numerals in parentheses are for comparison with the drawings, but do not limit the configuration of the present invention at all.

[0012]

According to the first aspect of the present invention, a projection is provided at a central portion of a hollow portion where a recess is easily formed due to depression on the outer surface of the rim by welding, thereby increasing the wall thickness. In this case, it is possible to prevent the occurrence of a defective product due to the formation of a concave portion, and the other portion around the hollow portion needs to have a relatively small thickness, so that the weight of the rim does not increase significantly. In particular,
Since the outer surface of the bead seat opposite part can be seen from the outside even when the tire is mounted, providing a protrusion on the bead seat opposite part to prevent the occurrence of depressed concave parts will greatly reduce the occurrence of defective products Can be.

If the thickness of the projection is less than 1.3 times the surrounding reference thickness, the effect of preventing the formation of the concave portion due to the depression is not sufficient, and the effect is obtained. Therefore, 2.0 times or more is not necessary, which causes an increase in the weight of the rim.

According to the second aspect of the present invention, the bead seat portion is also provided with a protrusion opposed to the protrusion opposite to the bead sheet, and the both protrusions are formed by a relatively small upset pressing amount. Since the burrs are bridged to form a columnar shape, it is possible to prevent the molten metal from bulging further inward, thereby preventing the rim outer surface from being pulled in and reliably preventing the occurrence of a recessed concave portion on the rim outer surface. it can.

According to the third aspect of the present invention, since the top of the projection is formed of a flat surface having a predetermined length, in the range of the wall thickness of 1.3 to 2.0, a concave portion is generated due to the depression of the outer surface. Can be configured to have a wall thickness increasing portion having a sufficient length to prevent the occurrence of the problem.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a wheel rim for a motorcycle, which is formed by bending an aluminum alloy mold having a sectional shape as shown in the figure into an annular shape and joining both ends by flash butt welding. .
The rim 1 has a flange portion 2 standing obliquely outward on both sides thereof, a bead seat portion 3 extending substantially flat inward in the width direction from the base portion of the flange portion, and a radially inward direction at a center portion in the width direction. And a well 4 which is recessed.

The bead seat portion 3 of the rim 1
A hollow portion 5 having a predetermined shape is formed on the inner diameter side of
The outer side a of the bead seat portion 3 opposite to the hollow portion is configured to be an arc surface. Further, the inner diameter portion of the well portion 4 in the rim 1 has substantially the same thickness, and an outer surface b opposite to the well portion 4 forms a curved surface smoothly continuing from the bead seat portion outer surface a. are doing. Further, the outer surface of the flange portion 2 has an arc surface substantially continuous with the bead seat portion outer surface a at the base portion thereof, and the front end portion c thereof has a left and right curved surface with a curvature in the opposite direction. It is curved outward in the width direction. In addition, the bead seat portion 3 is formed of a flat surface having a slight downward slope (about 5 degrees) from the left and right outer sides toward the center,
Further, a hump portion 3a slightly protruding at a connection portion with the well portion 4 is formed.

As shown in FIG. 2, the hollow portion 5 has the same thickness t ₁ as the bead sheet portion 3 having a predetermined thickness t ₁ (for example, 2.5 [mm]). It is configured to be surrounded by a bead seat opposite portion 6 constituting the side surface a and a well recessed portion 7 having a thickness t ₂ (for example, 2.0 [mm]) slightly smaller than the above thickness. The hollow part 5 has a substantially triangular shape having a vertex angle on the flange side as a whole and extending in the width direction, and its corners e, f, and g are formed of arc surfaces having different radii.

Further, the hollow portion 5 is provided with projections 5a and 5b projecting toward the hollow side at a substantially central portion in the width direction and continuously formed in the circumferential direction. The bead seat portion side protrusion 5a
One side is an arc surface (for example, radius 3
[Mm]), and the other side is formed with a radius of a predetermined radius (for example, 2 [mm]),
The top part h is formed of a flat surface having a predetermined length l ₁ (for example, 1.5 [mm]). Also, the opposite protrusion 5b is
One side is formed with a radius of a predetermined radius (for example, 5 [mm]), and the other side is formed with a predetermined radius (for example, 1.5 [m]).
m]), the top i of which is a predetermined length l
₂ (for example, 2.5 [mm]). The top flat surface i of the opposite protruding portion 5b is substantially inclined along the outer side surface a. line) to the perpendicular to the width direction of the reference line L-L is to be the same length l ₁ and the top flat surface h of the bead seat portion side projections 5a, it is formed opposite.

The thickness t of the projections 5a and 5b
₃ and t ₄ are 1.3 to 1.3 with respect to the thickness t _{1 of the} bead seat portion 3 and the sheet opposite portion 6 which serve as the reference around it.
2.0, preferably in the range of 1.4 to 1.6. Specifically, the thickness t ₃ of the sheet portion side protrusion 5a is
The thickness t ₁ of the bead sheet portion 3 is 3.5 [mm], whereas it is 2.5 [mm], and therefore is 1.4 times, and the thickness of the opposite side protrusion 5 b is also large. t ₄ is the thickness of the bead seat opposite part 6 is 2.5 [mm] to consist 4.0 [mm], thus has a 1.6 times.

FIG. 3 is a cross-sectional view of the flash butt-welded portion, and welding burrs are formed on the outer surface of the rim and the inner peripheral surface of the hollow portion 5 by the upset accompanying the welding.
The burr on the outer surface of the rim is removed by grinding and grinding with a cloth, but the burr 10 on the inner peripheral surface of the hollow portion is left as it is. The burr 10 on the inner peripheral surface is easily bulged inward in the widthwise central portion of the hollow portion 5 which is long in the width direction by the pressing by the upset, and as a result, the protrusions 5a and 5b are formed. In the case of the non-existent one, the recessed portions 11a and 11b as shown by chain lines are apt to be formed on the corresponding outer surface as the molten metal (flesh) bulges into the hollow portion and the outer surface is drawn in. The depressed concave portion, particularly the depressed concave portion 11b on the opposite side of the bead seat portion, remains as a flaw (ecbo) after removing burrs on the outer surface by grinding or the like.

In the present embodiment, the depression 1
1a, the easy part occurs 1b, the projections 5a, 5b are formed, the partial wall thickness t _3, t ₄ is compared to the thickness t ₁ of the portion 5, 7 as a reference wall of the surrounding The thickness is 1.3 to 2.0 times thicker. As a result, even when the pressing amount at the time of the upset is small, the influence on the rim outer surface is reduced based on the large thicknesses t ₃ and t _4, and the occurrence of the concave portion due to the depression is prevented. At this time, if the thickness of the protruding portions 5a and 5b is 1.3 times or less of the reference wall thickness, the above effect is not sufficient, and 2.0% is required to obtain the above effect.
More than twice is not necessary, and adverse effects such as a cause of an increase in the rim weight become apparent.

The tops h, i of the projections 5a, 5b
Is composed of flat surfaces having predetermined lengths l ₁ and l ₂ ,
In the above thickness range of 1.3 to 2.0, it is possible to form a wall thickness increasing portion by a protrusion having a length sufficient to prevent the occurrence of the concave portions 11a and 11b due to the depression of the outer surface of the rim. . Further, the protrusions 5a and 5b are formed to have predetermined lengths l ₁ and l
₂ and are opposed to each other, even with a relatively small upset pressing amount, as shown in FIG. 3, the burrs 10 from these two protruding portions 5a and 5b bridge each other to form a columnar 10a. This prevents the rim outside surface from being pulled in due to the further inward swelling of the molten metal, so that it is possible to reliably prevent the occurrence of a concave recess on the rim outside surface.

In the above-described embodiment, the rim in which the outer surface a of the bead seat opposite portion 6 has an arc surface has been described. However, the present invention is not limited to this, and the bead seat opposite portion substantially parallel to the bead seat portion may be used. The present invention can be similarly applied to rims having other shapes, such as a rim. In this case, it is needless to say that the shape of the hollow portion changes according to the rim shape. Also, the shape of the hollow part,
Depending on the length in the width direction or the like, the protrusion does not necessarily have to have a flat top at the top, and may have another shape such as a round shape. Further, the projection formed substantially at the center of the hollow portion may be provided only on the bead seat opposite portion 6 constituting the outer surface a exposed to the outside, even in the tire mounted state.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a light alloy wheel rim according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the hollow portion.

FIG. 3 is an enlarged view showing a welded portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wheel rim made of light alloy 2 Flange part 3 Bead seat part 4 Well part 5 Hollow part 5a, 5b Projection 6 Bead seat opposite part 10 Burr 11a, 11b Depressed concave part h, i Flat surface

Claims (3)

[Claims] 1. A light-alloy wheel rim, which is formed by joining both ends of an annularly curved light-alloy mold material by welding and has a hollow portion extending in a width direction on an inner diameter side of a bead seat portion, A protrusion having a thickness of 1.3 to 2 times the thickness of the opposite portion is formed on at least the opposite side of the bead sheet at the substantially central portion in the width direction of the hollow portion. A light alloy wheel rim. 2. A projecting portion is formed at a substantially central portion of the hollow portion in the width direction on the side of the bead seat portion facing the hollow portion opposite to the bead seat portion. The wheel rim made of light alloy according to 1. 3. The light alloy wheel rim according to claim 1, wherein the protrusion has a top formed of a flat surface having a predetermined length.