JP2005180599A - Structure for preventing electrolytic corrosion of clamping portion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for preventing the electrolytic corrosion of a clamping portion, which structure can maintain the insulation property and can prevent the corrosion due to the electrolytic corrosion. <P>SOLUTION: The structure for preventing the electrolytic corrosion of the clamping portion made of light alloy connects a first boss portion (8) and a second boss portion (9) opposed to each other across a clearance by means of a bolt (4) made of steel. A first male screw (16) and a second male screw (17) are formed on both end portions of the bolt. The bolt is made so as to penetrate the bolt hole (15) of the second boss portion (9), and the first male screw of the bolt is engaged with a threaded hole (31) formed in the first boss portion (8) so as to stand therefrom. The first and second boss portions are tightened by means of a nut (6) to be engaged with the second male screw of the bolt protruding from the second boss portion. An insulation coating layer having insulation property is formed at least on the surface of the bolt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a structure for preventing electrolytic corrosion of a clamp portion.

  As shown in FIG. 3, the conventional clamp portion structure is formed by passing the bolt 72 through the second boss portion 79 of the bracket 71 and screwing the bolt 72 into the screw hole formed in the first boss portion 78. The first and second boss portions 78 and 79 separated by 75 are clamped.

  In addition, there exist some which are disclosed by patent document 1 in the structure of a clamp.

  By the way, when two different metals are brought into contact, there is a problem that the contact portion is corroded by electrolytic corrosion.

  For example, when a magnesium (Mg) alloy member, which is a light alloy, is fastened using an iron-based bolt, electrical corrosion (electric corrosion) between Mg and iron occurs in the presence of moisture. In particular, when it is used in parts that are subject to muddy water such as undercarriages of motorcycles and automobiles, or parts that are prone to snow melting salt in snowy areas, moisture adhesion in the presence of electrolytes (Na +, Ca2 +, Cl-, etc.) Electric corrosion may progress violently.

In order to solve this problem, in general, an insulating coating is formed on the surface of the bolt 2 to form an insulating layer, thereby preventing electric corrosion.
JP 2003-239934 A

  However, in the structure of the conventional clamp part, when the bolt 72 is repeatedly loosened or tightened by replacing parts or the like, the insulating layer of the bolt 72 is destroyed due to wear and electric corrosion occurs.

  Therefore, the object of the present invention is to solve the above-mentioned problem, and even if the bolt is repeatedly loosened or tightened, the insulation is maintained between the bolt and the first and second boss portions, and electrolytic corrosion is prevented. It is to provide an electrolytic corrosion prevention structure for a clamp part.

  In order to achieve the above object, the first invention is an electroerosion prevention structure for a light alloy clamp part in which first and second boss parts facing each other through a gap are fastened through an iron-based bolt. First and second male screws are formed at both ends of the bolt, the bolt is passed through the bolt hole of the second boss portion, and the first male screw of the bolt is screwed into the screw hole formed in the first boss portion. The first and second boss portions are fastened through nuts that are implanted and screwed into the second male threads of the bolts protruding from the second boss portions, and an insulating coating layer having insulating properties is formed on at least the surface of the bolts. Electrolytic corrosion prevention structure of the clamp part characterized by this.

  According to a second invention, in the first invention, a washer is interposed between the second boss portion and the nut, and an insulating coating layer having insulating properties is formed on the surface of the washer.

  According to a third invention, in the first or second invention, the clamp portion is formed of a magnesium alloy, and the fluororesin coating layer is formed on the entire surface of the bolt.

  According to the first invention, even if the bolt is repeatedly loosened or tightened, the bolt does not rotate in the bolt hole, and the insulation coating layer of the bolt is not destroyed by wear. Can be prevented.

  According to the second invention, by providing a washer having an insulating coating layer formed between the nut and the second boss portion, even if the bolt is loosened or tightened repeatedly, the washer keeps the insulation, Corrosion due to food can be prevented.

  According to the third invention, by forming the fluororesin coating layer on the entire surface of the bolt, the insulation is maintained and corrosion due to electrolytic corrosion can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an electrolytic corrosion prevention structure for a clamp portion according to this embodiment.

  The clamp part 50 is applied to a mounting part of a front fork for a motorcycle.

  The bracket 1 is connected to the steering shaft of the two-wheeled vehicle, and supports the outer tube 18 of the front fork via the clamp portion 50.

  The clamp part 50 reduces the diameter of the fork hole 12 formed in the bracket 1 by fastening the first and second boss parts 8 and 9 facing each other via the gap 5 via the stat bolt 4, and The outer tube 18 is tightened and fixed.

  As shown in FIG. 2, first and second male screws 16 and 17 are formed at both ends of the stat bolt 4.

  The stat bolt 4 is passed through the bolt hole 15 of the second boss portion 9, and the first male screw 16 of the stat bolt 4 is screwed into the screw hole 31 formed in the first boss portion 8 and implanted. The first and second boss portions 8 and 9 are fastened via nuts 6 that are screwed into the two male screws 17.

  The bracket 1 was formed of a magnesium alloy, which is a light alloy, and the stat bolt 4 was formed of an iron-based material.

  Anodizing treatment or chemical conversion treatment and coating are applied to the surface of the bracket 1 of the magnesium alloy member.

  A fluororesin coating layer was formed as an insulating coating layer having insulating properties on the entire surface of the stat bolt 4.

  A washer 7 is interposed between the second boss portion 9 and the nut 6. A fluororesin coating layer was formed on the surface of the washer 7 as an insulating coating layer having insulating properties.

  The surface treatment for forming the fluororesin coating layer on the surfaces of the stat bolt 4 and the washer 7 is performed by applying a base treatment to the surfaces of the stat bolt 4 and the washer 7 and then applying, for example, a tetrafluoroethylene-based fluororesin paint on the surface. A film is formed with a thickness of 20-30 μm.

  The coating film made of a tetrafluoroethylene-based fluororesin paint formed on the surfaces of the stat bolt 4 and the washer 7 has high adhesion to the surfaces of the iron-based stat bolt 4 and the washer 7, and is difficult to crack or peel off. Can maintain sex.

  The electrolytic corrosion preventing structure of the clamp part 50 is configured as described above and has the following effects.

  Since the stat bolt 4 is embedded in the first boss 8, even if the stat bolt 4 is repeatedly loosened or tightened, the stat bolt 4 does not rotate within the bolt hole 15, and the fluorine-based coating layer of the stat bolt 4 rubs. Therefore, corrosion due to electric corrosion can be prevented.

  By inserting a washer 7 having a fluorine coating between the nut 6 and the second boss portion 9, even if the stat bolt 4 is repeatedly loosened or tightened, the washer 7 can maintain insulation, Corrosion due to food can be prevented.

  The same effect can be obtained by forming a fluorine-based coating layer on the seat surface 11 of the nut 6 instead of interposing the washer 7 having a fluorine-based coating between the nut 6 and the second boss portion 9. Can be obtained.

  In the present embodiment, the fluorine-based coating layer is used as the insulating layer. However, the present invention is not limited to this, and other coatings may be used as long as the coating is hard and smooth and has insulating characteristics.

  In the present embodiment, the fluorine-based coating layer is formed on the surface of the stat bolt 4 as the insulating layer, but it may be formed on the inner surface of the bolt hole 15. Of course, a fluorine-based coating layer may be formed on both the surface of the stat bolt 4 and the inner surface of the bolt hole 15.

  Although the present invention has been described in certain terms with regard to structural and methodological features, the means disclosed herein include preferred forms of practicing the invention, and the invention is illustrated and described. It is not limited to specific features. Accordingly, the present invention includes any forms or modifications within the scope of the claims as appropriately interpreted in accordance with the principle of equality.

  The present invention can be applied to various clamp portions such as a clamp portion that supports a front fork of a motorcycle, other front fork components, a pump cover, and valves.

It is a figure which shows the electrolytic corrosion prevention structure of the clamp part by this invention. It is sectional drawing of the electrolytic corrosion prevention structure of the clamp part by this invention. It is a figure which shows the structure of the conventional clamp part.

Explanation of symbols

1 Bracket 4 Stat Bolt 6 Nut 7 Washer 8 First Boss 9 Second Boss 15 Bolt Hole 50 Clamp

Claims (3)

In the electrolytic corrosion prevention structure of the light alloy clamp part that fastens the first and second boss parts facing each other through a gap via an iron-based bolt,
First and second male screws are formed at both ends of the bolt, the bolt is passed through the bolt hole of the second boss portion, and the first male screw of the bolt is screwed into the screw hole formed in the first boss portion. The first and second boss portions are fastened through nuts that are implanted and screwed into the second male threads of the bolts protruding from the second boss portions, and an insulating coating layer having insulating properties is formed on at least the surface of the bolts. Electrolytic corrosion prevention structure of the clamp part characterized by this.   The electric corrosion prevention of the clamp part according to claim 1, wherein a washer is interposed between the second boss part and the nut, and an insulating coating layer having an insulating property is formed on the surface of the washer. Construction.   The structure for preventing electrolytic corrosion of the clamp part according to claim 1 or 2, wherein the clamp part is made of a magnesium alloy, and a fluororesin coating layer is formed on the entire surface of the bolt.

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