JPH0138575B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rim for an automobile wheel and a method for manufacturing the rim.

Conventionally, in a rim manufacturing method, a rim material 1 for forming a rim is obtained by cutting a coil material having a required width b into a required length L in the rolling direction and forming it into a cylindrical shape, as shown in FIG. , a method in which the joint surface is welded and then a predetermined forming process is performed to form the rim, or a wide coil material corresponding to the required length L of the rim material 1 is cut into the required width b as shown in Fig. 2. The method was to mold and process it.

However, in the former rim manufacturing method,
Since the rolling direction of the rim material 1 is the longitudinal direction of the material, the elongation in the circumferential direction is large even when formed into a cylindrical shape, making it easy to form, but the elongation in the rim section forming in the width direction of the rim is small. There were problems in that the rim section was prone to thinning and cracking during molding, and the durability of the rim section against bending stress under wheel load in the finished product was reduced.

In addition, in the latter rim manufacturing method, since the rolling direction of the rim material 1 is perpendicular to the longitudinal direction of the material, the durability against tensile loads in the circumferential direction during rim forming is low and forming is difficult. There were problems such as:

This invention aims to use a material that is compatible with the contradictory relationships between rolling direction and workability strength in the two manufacturing methods mentioned above, and to obtain a rim and a rim with good quality formed using the material. The present invention provides a method for manufacturing.

Embodiments of the present invention will be described in detail below with reference to FIGS. 3 to 6. FIG. 3 is an explanatory diagram showing the method of cutting out the rim material 1 according to the present invention, in which the required width B is obtained from a coil material having a wide coil width Lo.
Required length Lα, Lβ of rim material 1α or 1β at intervals of
The material is removed at a required angle of inclination α or β with respect to the rolling direction of the coil material so that If the above-mentioned required angle of inclination is 90°, it will be the same as that shown in FIG. 2, so 90° is not included in the required angle of inclination in this application.

The thus cut rim materials 1α and 1β are formed into a cylindrical shape with the width b direction as the winding axis, and then both end surfaces are butted together and welded to form a desired rim section to produce a rim.

That is, the required lengths Lα and Lβ of the rim material from the coil material with the wide coil width Lo can be arbitrarily set according to the required inclination angle α or β, and are determined by Lα=Locosecα Lβ=Locosecβ.

In this way, the cutting of the rim material according to the present invention allows the required length of the rim material to be arbitrarily set within a certain range from the coil material of the same width, and in the case of rims of the same thickness, the size The same coil material can be used even for different rims, and it is possible to reduce the variety of widths of the coil material.

Next, a processing method for forming a desired rim from the rim material 1 cut as described above will be specifically explained based on the process diagrams shown in FIG. 4 and subsequent figures.

First, the rim material 1 cut to a required length as shown in FIG. 3 is rolled up in step _S1 , both end surfaces are butt welded, the welded portion is trimmed, and the rim material 1 is formed into a cylindrical shape. This cylindrical product is stretched on both sides to form a drum shape in the flaring process of step _S2 , and then moves to the 1# roll shaping process of step _S3 .

In the above 1# roll shaping step, the rim flange is formed while enlarging its outer diameter, and the rim drop center portion is formed while its inner diameter is reduced. Thereafter, step _S4 , 2# roll shaping, and step _S5 , 3# roll shaping process are sequentially performed to roll form the rim section until it has the desired shape. The rim thus roll-formed into the desired shape is sized to the desired outer diameter in the sizing process of step _S6 , and the forming is completed.

In the above processing process, the flange part of the rim is mainly subjected to tensile processing that increases the outer diameter.
The drop center portion is formed by compressive deformation force.

However, in the roll forming process of the rim, the rim material 1 makes point contact with the lower roll 2 at points 2a and 2b at the base of the rim flange and the R part of the base of the drop center 1c, as shown in FIG. The upper roll 3 descends and rolls 3 onto the side wall of the drop center of the rim material 1.
Points a and 3b make point contact, and the drop center R portions 1a and 1b of the rim material 1 are pulled and rolled down by rolling down the rolls until the drop center of the lower roll 2 comes into contact with them. Since the rim material 1 is molded while being pressed, local thinning occurs at the drop center R portion of the rim material 1.

FIG. 6 shows a cross section of the mechanism during roll forming. The rim material 1 has a drop center portion with a radius R before being rolled, but the upper roll 3 rolls down and the lower roll 2 When the drop center portion is rolled down until it comes into contact with the drop center portion, the radius of the drop center portion is formed into R-Δr, and as a result, a compressive force acts in the circumferential direction.

As described above, the rim material 1 is deformed from a cylindrical shape by bending the rim section in a direction perpendicular to the circumferential direction and changing its diameter.

In this way, in the process of forming the rim, the rim is simultaneously subjected to tensile and compressive forces in the circumferential direction and tensile and compressive processes in the axial direction. The direction of the resultant stress of these two processing stresses is a direction inclined with respect to the axial direction of the rim cylinder.

Therefore, it is preferable that the rolling direction of the material coincide with or be close to this principal stress direction.

In other words, in the rim material according to the present invention, since the longitudinal direction is inclined to the rolling direction, the stress can be brought closer to the principal stress direction as described above, so that it can be processed with less local thinning. It becomes possible.

Furthermore, cracks in the rim that occur when the vehicle is running with the wheel mounted mainly occur along the circumferential direction, that is, the rolling direction, at the R portion of the flange root and the R portion of the drop center root.

This is because the side pressure due to the air pressure of the wheels, the vertical load, and the variable load stress direction due to rotation largely act in the axial direction. Therefore, it is preferable that the material of the rim be rolled in the axial direction during use, but there is a problem with workability, and currently the rolling direction is the circumferential direction. In order to improve these conflicting conditions, the rolling direction of the present invention is inclined from the axis.

As explained in detail above, in the rim manufacturing method according to the present invention, by cutting the material, a rim can be obtained which prevents the extreme thinning of the rim during the forming process, and also improves durability during running. This means that the thickness of the rim can be made thinner than that of conventional rims, making it possible to reduce the weight of the wheel.

In addition, in the planking method according to the present invention, the longitudinal dimension can be freely changed without changing the coil width, so the types of coil materials can be reduced, and the stock of coil materials can be reduced. There are advantages to reducing the amount.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing conventional rim material removal, FIG. 2 is a perspective view showing rim material removal from a wide coil, and FIG. 3 is an explanatory diagram showing rim material removal according to the present invention. FIG. 4 is an explanatory diagram showing the rim roll forming process according to the present invention, FIG. 5 is a partial sectional view showing the rim roll forming process, and FIG. 6 is a circumferential cross-sectional view showing the rim roll forming process. It is a diagram. 1...rim material, 2...lower roll, 3...upper roll.

Claims (1)

[Scope of Claims] 1. It is characterized by being formed from a biased flat plate material obtained by cutting a material of the required rim width so that the longitudinal direction of the rim has a required inclination angle with respect to the rolling direction of the wide coil. Rim to do. 2. With respect to the rolling direction of the wide coil, a bias flat plate material of the required rim width is taken so that the longitudinal direction of the rim is inclined at the required inclination angle, and the bias plate material is rolled into a cylindrical shape and both ends are butt welded, A rim manufacturing method characterized by forming a predetermined rim section through a required forming process.