JPS59217009A - Manufacture of iron group bolt into which washer made of aluminum alloy is incorporated - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing washer-integrated bolts used for fastening various members such as clutch cases, transmission cases, transmission cuckoos, plates, etc. made of magnesium alloys. Attempts are being made to manufacture cases and covers to reduce the weight of vehicle bodies and improve fuel efficiency. In order to assemble the members made of such magnesium alloy,
Magnesium is fastened with an iron bolt via an iron washer, but magnesium has the lowest standard electrode potential of any structural material, with a value of -2.4V.
The standard electrode potential of iron is -0.4V, so when a member made of magnesium alloy comes into contact with an iron washer or bolt, a battery with a potential difference of 2.0V is formed, and magnesium is eluted due to electrolytic corrosion. do".

Furthermore, even when galvanized washers and bolts are used, the standard electrode potential of zinc is -0.7, so a battery with a potential difference of 1.7μ is constructed, and as a result, magnesium elutes over time due to electrolytic corrosion. is unavoidable.

Therefore, when tightening a member made of a magnesium alloy with a bolt, it is considered that an aluminum alloy washer whose standard electrode potential is as low as -1.7V is interposed between the member and the bolt.

On the other hand, when tightening bolts, it is troublesome to attach a washer to the bolt each time the bolt is tightened, so a washer-equipped bolt with a washer attached to the bolt in advance is used to improve work efficiency. 0 And H to install the washer? Before thread rolling is performed on the bolt, a washer is attached to the bolt shaft, and after thread rolling the thread is hooked onto the inside diameter of the washer to prevent it from falling off the bolt. ! , Zn plating or 5rr on the bolt
- When applying Zn alloy plating, if the plating is not applied after thread rolling, bare metal Fe will be exposed on the threaded portion.

Therefore, when using a bolt with a plated washer, the washer must also be plated.

However, when the washer is made of an aluminum alloy, the washer itself is corroded because the plating is carried out by pickling and a highly acidic plating bath is used.

The present invention has been made to solve these conventional problems, and its purpose is to slow down the progress of electrolytic corrosion when bolting magnesium alloy members, and to improve assembly work efficiency. To provide a method for manufacturing an iron-based bolt incorporating an aluminum alloy washer with excellent properties.

In order to achieve the above object, the present invention first attaches a washer masked with an organic film to the shaft portion of an iron-based bolt material before plating, and then carves a threaded portion on the shaft portion of the iron-based bolt material by rolling. to prevent the washer from falling off, and then plate the iron bolt material with the washer attached.
The gist is that the film on the washer surface is then peeled off.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

7 Figure 1G) to (G) show the method of the present invention in the order of steps.In the method of the present invention, first, an aluminum alloy washer 1 as shown in Figure 1(A) is prepared, and this washer 1
As shown in FIG. 1(b), an organic film 2 of vinyl chloride or the like is masked on the surface of the film. As this organic film 2, one is selected that can protect the washer 1 even in plating pickling or a strongly acidic plating bath, which will be described later, and can be easily peeled off after plating.

On the other hand, prepare an iron-based bolt material 3 whose shaft portion 3a has not yet had a threaded portion as shown in FIG. 10-1, and mask the shaft portion 3a of this iron-based bolt material 3 with the organic film. Attach the washer 1 shown in Fig. 1).

Next, as shown in FIG. 1 (e), the shaft portion 3 of the iron bolt 3 is
A threaded portion 4 is carved in a by rolling. Then, the diameter of the thread becomes larger than the inner diameter of the washer 1, so when the washer 1 is removed from the shaft 3a, the surface of the washer 1 made of aluminum alloy is covered with an organic film, so it should not be exposed to a strong acid plating bath or acid. The aluminum alloy is not affected by washing.

As a final step, as shown in FIG. 1 (G), the organic film covering the surface of the aluminum alloy washer 10 is peeled off. Therefore, the washer-integrated bolt 5 is made by incorporating an aluminum alloy washer into a plated bolt.
get.

Fig. 2 shows a state of connection using the above-mentioned washer-integrated bolt. In the figure, 6 and 7 are members made of magnesium alloy such as automobile cases, and these members 6 and 7 are shown in Fig. 2.
Align the bolt mounting holes 6a and 7a with the tatsuzo machined holes drilled in the
These mounting holes 5a.

The members 6 and 7 are integrally connected by tightening the hooker 7a and the assembly bolt 5. Here, the member 6.7 and the bolt 5 are not in direct contact with each other at the exposed surface, but the aluminum alloy washer 1 is interposed, so that electrolytic corrosion is extremely difficult to proceed.

Incidentally, the washer-incorporated bolts obtained by the method of the present invention can be used to connect any member other than the transmission case, etc., and the plating applied to the bolts is Sn-Zn alloy plating, and Sn-Zn alloy plating is , It has better corrosion resistance than Zn plating (and is less likely to expose the steel plate than Zn plating. Therefore, as with the surface treatment of bolts, Sn-Z is recommended as a surface treatment for iron plates that come into contact with base parts.
N plating is the most suitable.

As explained above, according to the present invention, an aluminum alloy material that has been masked in advance with an organic film is plated, and then the organic film on the washer surface is peeled off. It is possible to obtain an iron-based bolt with a built-in washer, and if this bolt is used to connect magnesium alloy members, the standard electrode potential difference between aluminum and magnesium is 0.
．． Since it is extremely small at about 7V, it has many effects such as preventing electrolytic corrosion from progressing, greatly improving the durability of the member, and making it possible to assemble the member more efficiently.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the manufacturing method according to the present invention in the order of steps, and FIG. 2 is a diagram showing a state in which members are connected using a washer assembly bolt manufactured by the same manufacturing method. In the drawing, 1 is an aluminum alloy washer, 2 is an organic film, 3 is an iron-based bolt material, 3a is a shaft portion of the iron-based bolt material,
4 is a threaded portion, and 6 and 7 are members made of magnesium alloy. Patent Applicant Honda Motor Co., Ltd. Agent Patent Attorney 2 1) Yong - Immediate Question Patent Attorney Kuni Ohashi Otoma Patent Attorney Yu Koyama

Claims (1)

[Claims] After masking an aluminum alloy washer with a removable organic film and attaching this washer to the shaft of an iron-based bolt material, a threaded portion is carved into the shaft of the iron-based bolt material by rolling, and then the washer is attached to the shaft of the iron-based bolt material. A method for manufacturing an iron-based bolt incorporating an aluminum alloy washer, characterized in that 5n-Zn alloy plating is applied to the iron-based bolt material in a state in which it is attached, and then the organic film masking the washer is peeled off. .