JPH10236101A - Builtup magnesium alloy wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of contact corrosion by using a collared washer having a recessed cross section form and surface of such quality as having a small contact potential difference at the position where a tightening member such as a ferrous bolt and a nut comes in contact with a magnesium alloy. SOLUTION: An annular external flange 3b is formed along the peripheral part 3a of a disc 3, so as to mount the internal flange 2a of a rim 2 without any eccentricity. A bolt 6a is inserted in a hole drilled through the internal flange 2a of the rim 2 and the external flange 3b of the disc 3. In this case, a collared washer 7 is provided between the bolt 6a and the internal flange 2a, and between a nut 9 and the external flange 3b. The collared washer 7 is made of aluminum, or in the case of iron make, the surface thereof may be covered by zinc or beryllium plating at a thermal spraying process. According to this construction, the occurrence of corrosion due to the contact of the ferrous bolt 6a with the internal flange 2a of the rim 2, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembling type magnesium alloy wheel, and more particularly to a method for preventing corrosion of a fastening portion between a rim and a disk in an assembling type wheel.

[0002]

2. Description of the Related Art Vehicle wheels have been significantly reduced in weight in pursuit of improved driving stability and running performance. In recent years, aluminum alloy wheels have become the mainstream. The rate is 50%
Momentum close to. The production technology of light alloy wheels is roughly classified into forging and casting, but forging is superior in weight and rigidity of the wheel. On the other hand, in light alloy materials, although aluminum alloys are superior in terms of raw material price, difficulty of processing as a wheel, and maintenance, etc., comparing specific gravities of raw materials, magnesium is 1.74 and aluminum is 2.70 and magnesium is about 64% of aluminum. Magnesium is the lightest of the metals in practical use, but more importantly, its strength and rigidity per weight are high. That is, the magnesium alloy is excellent in specific strength (tensile strength / specific gravity) and specific proof stress (proof stress / specific gravity). Therefore, these are limited in the weight of the member, and are extremely effective when it is desired to improve strength and rigidity.

[0003] However, one of the reasons that magnesium alloys have not yet become mainstream for wheels is due to the price difference of raw materials, and the workability is difficult to spread, and special techniques are required especially in the casting and forging process. . Further, the biggest factor that hinders practical use of magnesium is that the corrosion resistance is low. Standard monopolar potential is -2.3 for magnesium
7. Aluminum is -1.66, indicating that it is a metal that can be easily bent out in a medium such as water or salt water.
Incidentally, that of iron is -0.44. Further, in the field of corrosion prevention technology, a magnesium metal is juxtaposed in order to protect one metal by using a contact potential difference to elute magnesium by using a contact potential difference to protect another metal. Under such circumstances, surface treatment of products made of magnesium is important, and chemical treatment (such as various chromic acid treatments) and electrochemical treatment (such as various anodic oxidation treatments) are performed.

Therefore, in an assembly type wheel structure in which a magnesium alloy and another metal are combined and integrated, it is necessary to take measures to prevent the metal connecting these pieces from coming into direct contact with the wheel body. In these assembled wheels (one-piece wheel, two-piece wheel, etc.), the rim and the disc are fastened with a plurality of bolts around the disc circumference, but the tightening bolts and nuts are made of iron or an alloy thereof. It has a large potential difference from magnesium, and magnesium corrodes rapidly when a medium such as water or salt water is interposed. As a corrosion prevention measure, each fastening member such as a bolt, a nut and a rivet is plated with zinc or cadmium to prevent contact corrosion. However, there is always a danger of corrosion such as strong frictional force generated on the plating film of the fastening member and damage to the film by rolling up sand or pebbles while the vehicle is running. There is no particular problem when touching, but if the salt water stays around the fastening member after traveling on the road where calcium chloride etc., which is an antifreezing agent in winter, is sprayed, the corrosion progresses rapidly . Therefore, a structure that effectively prevents corrosion without relying only on coating means such as plating and painting is desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a device capable of preventing contact corrosion between a fastening member of an assembled wheel made of iron and a wheel made of a magnesium alloy member. .

[0006]

SUMMARY OF THE INVENTION The present invention relates to a vehicle wheel made of a magnesium alloy assembled by using a tightening member such as an iron-based bolt, nut, rivet, or adapter made of alloy steel or stainless steel. And
Where the fastening member comes into contact with the magnesium alloy portion, a flanged washer having a concave sectional shape and a surface having a small contact potential difference is used.

The surface of the washer may be coated with a metal such as zinc, beryllium, cadmium, or aluminum having a small contact potential difference by means of plating or thermal spraying, or may be made of aluminum.

[0008]

The flanged washer in the wheel having the above-described structure can increase the distance between the fastening member and the magnesium alloy, so that a medium such as water or salt water does not stay between the both members.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view including the rotation axis of an assembled magnesium alloy wheel 1 according to the present invention. Reference numeral 2 denotes a rim, and a part of the outer rim and a part of the inner rim are shown. Reference numeral 3 denotes a disk, and an ornament 4 is fitted in the center. Reference numeral 5 denotes a bush made of aluminum, which is press-fitted into a disk, and is a portion to which a wheel nut is attached when the wheel is mounted on the hub flange of the axle.

An annular outer flange 3b is formed on the peripheral edge 3a of the disk 3 so that the inner flange 2a of the rim can be mounted without eccentricity. The bolt 6 is inserted into a hole penetrating the inner flange 2a of the rim and the outer flange 3b of the disk 3. At this time, a flanged washer 7 is mounted between the bolt head 6a and the inner flange 2a, and a flanged washer 7 is mounted on the screw side between the nut 9 and the disk outer flange 3b. FIG. 2A is an enlarged view for clarifying these portions. FIG. 2B is an enlarged plan view of the bolt head 6a and the washer 7 with the collar. In the present embodiment, the flanged washer is made of aluminum. However, if it is made of iron, it may be coated with zinc, beryllium, cadmium or the like on its surface by plating or spraying.

In FIG. 2A, the head 6a of the bolt 6 is shown.
Is composed of a serration portion 6a-1 on which a spanner is hung and an umbrella-shaped seat portion 6a-2. The flanged washer 7 has a concave cross-sectional shape, and is composed of an annular portion 7b like a flat washer and a flange portion 7a rising on the peripheral edge thereof. FIG. 2
As shown in (c), the places where the medium 8 such as water or salt water easily stays include the peripheral part of the seat part 6a-2 of the bolt head and the peripheral part of the ring part 7b of the flanged washer. The medium 8 does not connect over the brim 7a. Accordingly, there is no medium that short-circuits the iron-based bolt and the inner flange 2a of the magnesium alloy rim 2, so that contact corrosion can be prevented. This situation is the same on the nut 9 side. The shape of the bolt head is not limited to this example, and a general shape can be used, but a shape in which the distance between the bolt head and the magnesium alloy portion is long is preferable.

FIG. 3A is a sectional view showing an example using a rivet-type fastening member. Rivet 10
Is composed of a flat head 11 and a stem 12 as shown in FIG. 3 (b), and the stem 12 has grooves 13a, 13b parallel to two places.
And has a constricted portion 14 between the two groove portions. Further, using the adapter 15 shown in FIG.
The inner rim flange 2a and the outer flange 3b of the disc are sandwiched between the first rim 1 and the adapter 15, the groove 13b is gripped by a special pulling machine, the stem 12 is pulled, and the adapter 15 is caulked and fixed to the groove 13a. 14 is cut. For details, the applicant has disclosed Japanese Utility Model Application No. 6-65004.
Therefore, only a brief description will be given here. In this example, compared to using bolts and nuts,
Since the friction is not applied to the flanged washer, the coating for preventing the contact corrosion is less damaged.

[0013]

As described above, in the assembly type magnesium alloy wheel, the cross section is concave and the surface has a small potential difference at the point where the rim and the disk made of the magnesium alloy are fastened by the iron-based fastening member. The use of a washer with a characteristic collar prevents water, salt water, and other media that have a significant effect on contact corrosion from stagnating across the iron-based fastening member and the magnesium alloy part. Corrosion caused by the contact of the object can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view including a rotation axis of an assembled magnesium alloy wheel according to the present invention.

2A is an enlarged view of a bolt peripheral portion in FIG. 1, FIG. 2B is an enlarged plan view of a bolt head,
(C) is a sectional view showing a state in which the medium stays.

FIG. 3A is a cross-sectional view showing another embodiment,
(B) is a side view showing an example of a rivet, and (c) is a sectional view of an adapter used for the rivet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Assembly type magnesium alloy wheel 2 Rim 3 Disk 6 Bolt 7 Collar washer 9 Nut 10 Rivet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16B 43/00 F16B 43/00 Z

Claims (2)

[Claims] 1. A vehicle wheel made of a magnesium alloy assembled using a fastening member such as an iron-based bolt, nut, rivet, or adapter made of alloy steel, stainless steel, or the like, wherein the fastening member is made of magnesium. An assembling type magnesium alloy wheel using a flanged washer having a concave cross-sectional shape and a surface with a small contact potential difference at the point of contact with the alloy part. 2. The method according to claim 1, wherein the surface of the flanged washer is coated with a metal having a small contact potential difference with magnesium, such as zinc, beryllium, cadmium, and aluminum, by plating or thermal spraying. Assembled magnesium alloy wheel as described.