JPS5819372B2 - Manufacturing method of swing arm for motorcycles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a swing arm of a two-wheeled vehicle.

Conventional motorcycle swing arms have been made of pipes or presses, so the production costs for the molds are very high, and the molds must be changed every time the model is changed or the mounting position of the shock absorber is changed. Mold depreciation costs are high.

Furthermore, parts are welded and assembled to make a product.
The welding length was long and the manufacturing process was troublesome, resulting in poor productivity.

In addition, since there are many welded parts, the strength varies, making it unstable and having a poor appearance.

Furthermore, since the cross-sectional shape of the swing arm is restricted, there are various problems such as increased weight and low rigidity.

The present invention has obtained an epoch-making method of manufacturing a swing arm that solves the above-mentioned problems at once.To explain the drawings in detail below, Figure 1A2 shows the swing arm obtained by the present invention. , A is a plan view, and A is a side view.
1 is a swing arm, 2 is a pivot shaft that is pivoted to the vehicle body, and 33 is a rear axle shaft mounting portion 44', which is a rib formed protrudingly on the upper and lower edges of the swing arm 11.

The swing arm 11 is formed from a long member a by extrusion molding using a die, as shown in FIG. 2A.

This section a is made of a light metal such as aluminum material, and its cross-sectional shape can be arbitrary, but for example, it is advantageous in terms of strength if it has a closed cross-sectional shape as shown in the opening of Figure 2, and a rib C is formed on the upper or lower edge. It is.

The profile a obtained as described above is cut to the required length of the swing arm (cutting line b).

The front part of the thus obtained profile a is bent slightly inward as shown in Figure 1A, the pivot shaft 2 is welded to the front end, and the rear axle shaft attachment part 3 is attached to the rear end to form a swing arm. 11.

In addition, in order to reduce the weight of motorcycles for competition as much as possible, the ribs C formed on the above-mentioned profile a are pressed using a press or the like according to changes in the moment relative to the mounting part of the rear shock absorber d. Can be excised.

That is, as shown in Fig. 2C, the ribs C formed on the upper and lower edges of the profile a are cut out using a press or the like in order to gradually change the section modulus around the attachment part e of the rear shock absorber d. (The shaded area is the resection area).

In this case, even if the mounting position of the rear shock absorber d changes to the front or rear, the same shape can be used for the swing arm by simply changing the cutout accordingly.

Furthermore, in the swing arm according to the present invention, the axle shaft mounting portion 3 described above can be integrally formed with the section a.

That is, as shown in Fig. 3, the rib C of the above-mentioned section a is deviated to one side, or the rib C' is made to penetrate through the center, and this is placed at the highest end of the section a. Cut off leaving one side of the trunk of part a (shaded area in Figure 3 c).

That is, the flat plate-shaped portion obtained by the rib C and the remaining portion f of the body portion is used as the rear axle shaft attachment portion.

Although the cross-sectional shape of the profile a according to the present invention is arbitrary, examples are shown in Figure 4 A to G for reference.

The effects obtained by the present invention described above are as follows.

Cheaper than conventional press products.

Welding length can be reduced by less than half.

Stable strength can be obtained without any variation in strength.

It is possible to change the mounting position of the rear shock absorber by simply changing the shape of the cutout without modifying the mold.

A wide variety of cross-sectional shapes can be freely set depending on the purpose and function of the vehicle.

This is advantageous in terms of positionality.

You can reduce the cost of the hood. Productivity can be improved.

It can be manufactured with a beautiful appearance.

[Brief explanation of drawings]

Fig. 1 shows a swing arm obtained according to the present invention, A is a plan view and a side view of the frame, Fig. 2 A is a partial side view of an extruded section, and the opening is a cross-sectional view of the roller of Fig. 2 A; \ is a side view showing the forming process of the profile, 2 and HO are cross-sectional views of 212 and HO in Figure 2C, and Figure 3A is a side view of the profile. C is a sectional view of Rollo, C is a side view of the shaped material, and 2 and H are sectional views of 212 and Hoho in FIG. 3C. FIG. 3 is a sectional view showing another example of FIG. 3E. FIG. 4 is a cross-sectional view showing various cross-sectional shapes of the profile.

Claims (1)

[Scope of Claims] 1. After cutting a long light metal shape extruded into a desired cross-sectional shape with ribs on the upper or lower edge to a required length, a part of the ribs is cut into a section modulus of the shape. Method for manufacturing a swing arm for a two-wheeled vehicle, characterized in that the swing arm is formed by cutting the swing arm to change the shape of the swing arm.2 A long light metal shape extruded into an arbitrary cross-sectional shape with a rib on the upper or lower edge. A method for manufacturing a swing arm for a two-wheeled vehicle, characterized in that the swing arm is formed by cutting the shape material to a required length, and then cutting off the end portion of the shape material to provide a mounting portion for a rear axle shaft.