JPH09123723A - Wheel support member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable junction by which no chill is produced at a joint and to make a wheel support member lightweight by integrating a main body part made from nodular graphite cast iron and involving an arm part with a spindle part through friction pressure welding, the spindle part being made from a steel type material. SOLUTION: A knuckle spindle 1 serving as a wheel support member comprises a main body part 2, manufactured from nodular graphite cast iron and involving an arm part 5, and a spindle part 3 manufactured from a steel type material, which is joined to the main body part 2. At a friction pressure of 5 to 15Mpa and in a friction time of 30 to 60 seconds, the main body part 2 and the spindle part 3 are moved relative to each other while being rubbed against each other, after which upsetting is performed at an upset pressure of 20 to 60Mpa and in an upset time of 2 to 4 seconds to integrally join them 2, 3 together. Then no chill exists at the boundary of their junction, and junction of them can be performed well in a state approximating solid-phase welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel support member, and more particularly, to a wheel support member in which a main body portion including a separately manufactured arm portion and a spindle portion are integrated by friction welding.

[0002]

2. Description of the Related Art Conventionally, as a suspension device for an automobile, as disclosed in, for example, Japanese Patent Laid-Open No. 58-67508, a wheel supporting member for supporting a wheel is integrally provided with an arm portion above the upper end of the wheel. The two upper arms are swingably connected to the upper ends of the arm portions, respectively, and the other ends of the two lower arms are swingably connected to the vehicle body at the lower portion of the wheel support member, thereby swinging the wheel support member with respect to the vehicle body. There is a double wishbone type suspension that supports it as much as possible.

The wheel support member described in Japanese Patent Laid-Open No. 58-67508 is integrally formed by casting, including the arm portion, and a large mold is required. In the casting of the wheel supporting member using this large mold, it is difficult to manufacture a casting mold suitable for the wheel supporting member having a complicated shape. In order to improve this, JP-A-3-193512 discloses that a wheel support member is divided into a main body portion and an arm portion, and a joint portion between them is formed as a cross-sectional area larger than other portions,
There is a disclosure of a method for manufacturing a wheel supporting member in which both are joined by friction welding.

[0004]

SUMMARY OF THE INVENTION The above-mentioned JP-A-3-193 is disclosed.
According to Japanese Patent Laid-Open No. 512, there is a risk of breakage when excessive stress is applied to the joint between the main body and the arm, and since the cross-sectional area of the joint between the main body and the arm is large, weight reduction is achieved. It is relatively difficult. The present invention has been made in view of the above problems, and an object of the present invention is to provide a wheel support member that is light in weight of a main body portion including an arm portion and that is frictionally pressure-welded favorably in terms of structure and strength.

[0005]

Means for Solving the Problems The present inventors have found that when spheroidal graphite cast iron and steel-based material among cast iron materials are subjected to normal friction welding,
Graphite in spheroidal graphite cast iron is compressed by upset pressure (pressure contact pressure) to form a thin film, forming a lubricating layer,
It was thought that it hindered the concentrated friction and heat generation, which are the original advantages of the friction welding method. As a result of various studies on the conditions of friction welding, the upset pressure was set to be higher than that for steel-based materials and set to a shorter time, so that the friction heat of both the spheroidal graphite cast iron and the steel-based material caused a re-upset. It was found that the melted molten layer is extruded to the outside, and the frictionally pressure-bonded joint can be secured in a state close to that of solid-state welding, chilling does not occur, and the welding becomes good.

Further, as in the case of a wheel supporting member for an automobile, the spindle portion in which the bearing is fitted to support the wheel should not cause any settling even if the wheel is loaded and rotates. For this reason, it is preferable that a steel material is used for the spindle portion, and after this is machined into a predetermined shape, heat treatment such as quenching and tempering is performed. Therefore, the main body portion including the arm portion,
If the spindle part is formed as a separate body and the main body part is made of spheroidal graphite cast iron and joined by friction welding, the above-mentioned Japanese Patent Laid-Open No.
Similar to the 193512 publication, a very large casting frame is not required at the molding site, no settling occurs in the spindle portion, and the spheroidal graphite cast iron is lighter than conventional materials,
The present invention has been conceived, focusing on the effect of reducing the weight of automobiles.

That is, the wheel supporting member of the present invention is characterized in that the main body portion made of spheroidal graphite cast iron and including the arm portion and the spindle portion made of steel material are integrated by friction welding. Further, the wheel support member is a knuckle spindle. And the friction welding part is
It is characterized by the fact that there is no chill and that it is formed by a bond close to solid phase bonding.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the wheel supporting member of the present invention, the friction pressure during friction welding is set low and the friction time is set long so that the temperature gradient around the joint of the materials becomes gentle. Also, the upsetting pressure after that is increased and the upsetting time is shortened to perform the joining. As a result, there is no chill in the friction welded joint, and the joint can be secured in a state close to solid-state welding.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of an essential part of a knuckle spindle as a wheel supporting member obtained by a friction welding method according to an embodiment of the present invention. The knuckle spindle 1 comprises a main body 2 including an arm 5 made of spheroidal graphite cast iron, and a spindle 3 made of a steel material to be joined to the main body 2. The main body portion 2 and the spindle portion 3 are manufactured separately. In addition, 4 is a joining part. Therefore, the main body portion 2 does not require a special large-sized molding flask, and does not require installation of large-scale molding equipment by new investment.

In order to obtain the wheel supporting member 1 of the present invention, the friction pressure is 5 to 15 MPa, the friction time is 30 to 60 seconds, the main body portion 2 and the spindle portion 3 are moved relative to each other while rubbing, and then the upset pressure 20. Upset is performed at -60 MPa and an upset time of 2-4 seconds. The main body 2 is cast from a spheroidal graphite cast iron FCD700 material to be machined including the portion friction-welded to the spindle portion, and the spindle portion 3 is made of steel, and the machining, heat treatment and bearing are fitted. Each part is manufactured separately by grinding the parts. Since the main body part includes the arm part, the weight is reduced to an optimal shape by strength calculation. At the boundary of the joint, there is no chill and the joint is very good.

[0011]

As described above, the wheel support member of the present invention has a main body made of spheroidal graphite cast iron and a spindle portion made of a steel material and including an arm portion, which are friction-welded to each other to chill the joint portion. Since it does not exist, it is bonded close to solid-phase bonding, it is possible to reduce the weight, and the structure and strength are well bonded, and no settling occurs in the spindle portion.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part of a knuckle spindle obtained by a friction welding method according to an embodiment of the present invention.

[Explanation of symbols]

1: Knuckle spindle, 2: Main body part, 3: Spindle part, 4: Friction welding part, 5: Arm part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimiki Otsuka 11 Kinugaoka, Moka City, Tochigi Prefecture Inside the Materials Research Laboratory, Hitachi Metals Co., Ltd. (72) Inventor Yoshitaka Ito 2-2 Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Susumu Kadota 2-2-1 Marunouchi Marunouchi, Chiyoda-ku, Tokyo Inside Automotive Equipment Division, Nitate Metal Co., Ltd.

Claims (3)

[Claims] 1. A wheel support member comprising a main body made of spheroidal graphite cast iron including an arm portion and a spindle portion made of a steel material, which are integrated by friction welding. 2. The wheel support member according to claim 1, wherein the wheel support member is a knuckle spindle. 3. The wheel support member according to claim 1, wherein the friction welding portion has no chill and is formed by a joint close to solid-phase joining.