JPS6257405B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is applicable to an irregular shape in which the cross-sectional shape in the direction orthogonal to the longitudinal direction is asymmetrical, such as an automobile tire wheel or a side ring that is an assembly part thereof. The present invention relates to a processing method for forming a bar material having a cross-sectional shape into a cylindrical shape by tilting the main axis of the cross-section of the material.

(Prior art) Conventionally, wheel rims having a flange portion on one side and a gutter portion on the other side along the circumferential direction, and side rings used for such wheel rims, have been formed into a cylindrical shape. When forming a bar material with an irregular cross-sectional shape whose cross-sectional shape is asymmetrical in the direction perpendicular to the longitudinal direction of the bar material into a cylindrical shape while curving it in the longitudinal direction of the bar material, a bending roller or the like is used. The process involved rolling the material into a cylindrical shape while sequentially curving it in its longitudinal direction.

(Problems to be Solved by the Invention) However, in the case of the above-mentioned conventional processing method, when rounding the material, the main axis direction line and the central axis of the cylindrical body are not parallel, so that
The main axis direction and the central axis of the cylindrical body are wound into a cylindrical shape while being inclined to each other, and as a result, for example, in the case of a wheel rim, a strong tensile force acts in the circumferential direction on the flange side, resulting in thinning. On the other hand, strong compressive force acts on the gutter side, causing problems such as thickening and twisting, which has a large impact on product yield.

(Means and effects for solving the problems) The present invention is the result of repeated various experiments and research in order to solve these conventional difficulties, and finally a fundamental solution has been found. Specifically, when rounding a bar material whose cross-sectional shape in a direction perpendicular to the longitudinal direction is asymmetrical into an annular shape, the bar material is curved in the longitudinal direction to form a cylindrical shape. A camber with a radius of curvature centered on the intersection of the main axis direction line of the axial cross section of the cylindrical body and the central axis of the cylindrical body when molded is given in advance along the longitudinal direction of the bar material, and the bar with the camber is The material is characterized in that it is molded into a cylindrical shape while being curved by a weighting axis parallel to the main axis direction line.

The specific content of the present invention will be explained below based on illustrated embodiments. Figures 1 to 3 show the case where the present invention is applied to a rim for a tire wheel, and in the figures, 1 is the rim. and a rim flange 2 continuous in the circumferential direction on one side,
Further, the other side similarly has a gutter portion 3, respectively. In such a wheel 1, the flange is functionally expanded outward from the plane of the rim base W, while the gutter portion 3 is configured to contract in diameter from the plane of the rim base W in the direction of the rotation axis.

Therefore, the main axis M of the wheel 1 in this case is at a position passing the rim base W in an oblique direction as shown in FIG. Therefore, with the centroid G as the boundary, the center line of wheel 1 (rounding axis)
The part where the distance from C is long, that is, especially the flange 2
In this case, tensile force acts on the material during molding, causing cracks, and conversely, strong compressive force acts on the part where the distance from the center line is closer than the centroid G, especially in the gutter part 3. It is thick and tends to be twisted easily.

In the present invention, the centerline C of the rim 1, whose cross-sectional shape in the direction orthogonal to the longitudinal direction of the material has an asymmetrical irregular cross-sectional shape, intersects with the extension line of the main axis M passing through the centroid G of the rim 1. A rim material with a camber of curvature corresponding to the radius r centered at the intersection O, that is, the main axis direction line of the axial cross section of the cylindrical body when it is curved in the longitudinal direction and formed into a cylindrical shape, and the central axis of the cylindrical body A rim material 1 is prepared in advance, as shown in FIG. 2, on which a camber with a radius of curvature centered at the intersection point with the rim material is provided with a camber along its longitudinal direction.

This camber curvature is determined by the inclination angle θ of the main axis M with respect to the center line C and the winding diameter (Dφ) of the rim 1.
Although it is not necessarily a constant ratio depending on the curvature of the flange and other conditions, if other conditions are not taken into account, the standard is rg = Dg / 2sinθ. The ideal curvature of the rim material can be found using the relational expression.

In this case, the camber can be applied to the rim material during the hot rolling process, for example.

The rim material 1 having a camber with a predetermined curvature thus obtained is sequentially bent and rolled into a cylindrical shape using, for example, a bending roller, around a cylindrical axis parallel to the direction line of the main axis M, thereby forming a cross section of the rim. It is possible to easily form the mold in the direction of the smallest coefficient, and the rolled-up rim can form a parallel cylindrical portion as shown in FIG. Then, by butt welding the rounded ends, the ideal rim anticipated by the present invention is completed.

Although the above example is applied to a tire wheel, the present invention is not limited to these examples, but can be applied to side rings S having any irregular cross-sectional shape, as shown in Fig. 3. Applies to everything that is rounded, including

Incidentally, the curvature camber that should be applied in advance to the side ring S before processing is as shown in FIG.

(Effects of the Invention) As is clear from the description of the above-mentioned embodiments, the present invention applies to a material having an irregular cross-sectional shape that is asymmetrical in the direction perpendicular to the longitudinal direction.
When curved in the longitudinal direction and formed into a cylindrical shape, a camber with a radius of curvature centered at the intersection of the main axis direction line of the axial cross section of the cylindrical body and the central axis of the cylindrical body is drawn along the longitudinal direction of the material. In addition to applying the camber in advance, the material with the camber is curved by a bending axis parallel to the main axis direction and rolled into a cylindrical shape, so that the material whose main axis is tilted as in the past is restrained and forcibly shaped into a circular shape. There is no need for a special forming device to wrap the round, and the rounding process can be easily and accurately performed by using a general-purpose bender device. It has various beneficial effects such as uniformity or no twisting at all, and therefore various high-quality rounded products can be easily obtained, resulting in extremely good product yields.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the inclination angle state of the main axis M when the present invention is applied to a tire wheel rim, FIG. 2 is a plan view of the rim material before processing, and FIG.
The figure is a sectional view showing the main axis of the side ring when the present invention is applied to a side ring material for a wheel, and Figure 4 is an explanatory diagram showing the curvature camber to be given in advance to the side ring of Figure 3. It is. 1...Rim, 2...Flange, 3...Gutter step, C...Center line, M...Main shaft, G...
Center of gravity, S... side ring.

Claims (1)

[Claims] 1. When a bar material whose cross-sectional shape in the direction orthogonal to the longitudinal direction is asymmetrical is formed into a cylindrical shape by curving it in the longitudinal direction, the main axis direction line of the axial cross-section of the cylinder and the cylinder A camber with a radius of curvature centered at the point of intersection with the central axis of the body is given in advance along the longitudinal direction of the bar material, and the bar material with the camber is curved with a bending axis parallel to the main axis direction to form a cylinder. A method for rounding irregularly shaped materials, which is characterized by forming them into shapes.