GB2415025A

GB2415025A - Fastening structure with abrasive layer

Info

Publication number: GB2415025A
Application number: GB0511608A
Authority: GB
Inventors: Akira Ohkubo; Toshihiro Takeuchi; Koji Tagome; Katsunori Itakura; Yasushi Okamoto; Tadamichi Tokuhisa
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2004-06-07
Filing date: 2005-06-07
Publication date: 2005-12-14
Anticipated expiration: 2025-06-07
Also published as: GB2415025B; GB0620508D0; GB0511608D0; GB2428279A; GB2428279B; JP2006022948A

Abstract

A fastening structure includes a first member (2), a second member (3) and a fastening member (4, 5) for joining first and second members (2, 3). There is an abrasive layer (1) between first and second members (2, 3).

Description

241 5025

FASTENING STRUCTURE

The present invention relates to a fastening structure having two members fastened with a fastening member such as a through bolt, and in particular relates to a fastening structure which can prevent slipping between the two members, prevent generation of noise, and prevent loosening of screws.

In a fastening structure having two members fastened to each other, when an external force is to either of the two members in a horizontal direction, slipping occurs between the fastening surfaces of the two members, so that noise is generated and loosening of screws occurs. Due to this, in a conventional fastening structure having two members fastened to each other, fastening force must be increased by increasing the friction coefficient between the fastening surfaces of the two members. There are techniques to increase the fastening force. For example, the size of a fastening member such as a bolt may be increased, the number of fastening members may be increased, a pin may be used together with a fastening member, an adhesive may be applied between fastening surfaces, or fastening surfaces may be subjected to knurling working, shot processing, or spraying processing (see Japanese Unexamined Patent Application Publication No. 2000-154849). However, in the above techniques, since sufficient effects cannot be obtained, and modification and machining of the ncnbers are required, mass produced members cannot be used as they are.

Since individual processing is required, work processing is troublesome.

In order to solve the above problems, a fastening portion structure is proposed in which crystalline grains composed of silicon carbide are disposed between two members and bridge the two members so as to be connected (see Japanese Unexamined Patent Application Publication No. 2002-130223). In this fastening portion structure, the adhesive is applied to a fastening surface of the one member, the crystalline grains composed of silicon carbide are uniformly sprayed thereon, and after that, fastening surfaces of the two members are contacted with each other and are fastened with a fastening member.

However, in the above fastening portion structure in which the crystalline grains composed of silicon carbide are used, since the crystalline grains composed of silicon carbide are sprayed on the surface of the applied adhesive layer, the process is troublesome, a serious dust problem is caused by the scattering of the crystalline grains composed of silicon carbide, and slipping of the fastening surfaces and creeping of axial force occur.

Therefore, the present invention was made to solve the above problems, and an object of the present invention is to provide a fastening structure which can prevent slipping between two members, prevent generation of noise, and prevent loosening of screws.

The present invention provides a fastening structure including: a first member composed of metal and having a fastening surface; a second member composed of metal and having a fastening surface; a fastening member for fastening the first and the second members in a state in which the fastening surface of the second member is adjacent the fastening surface of the first member; and an abrasive holding layer formed between the first and the second members, the abrasive holding layer containing an abrasive, wherein during the fastening of the first and the second members, portions of the abrasive are embedded in the fastening surfaces, and the abrasive is held by the first and the second members.

According to the present invention, the abrasive holding layer containing the abrasive is formed on either of the fastening surfaces of the first and the second members, so that the abrasive can be uniformly disposed on the fastening surface. In fastening the first and the second members having the abrasive holding layer therebetween, portions of the abrasive are embedded in the respective fastening surfaces, and the abrasive is held by the first and the second members, so that the friction coefficient between the first and the second members is increased, and slipping between the first and the second members can thereby be inhibited, and generation of noise and loosening of screws can be prevented. Since the friction coefficient between the first and the second members is increased, the fastening member can be made compact, and the production cost of the fastening structure and the weight of the fastening structure can be reduced.

Preferred embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Fig. 1 is a diagram showing an example of a desirable feature of a fastening structure of the present invention.

Fig. 2 is an enlarged diagram of the periphery of an abrasive of Example 1 of a fastening structure of the present invention.

Fig. 3 is a diagram showing an example of a desirable feature of an abrasive holding layer in a fastening structure of the present invention.

Figs. 4A and 4B are diagrams for explaining an increase in slipping resistance by a desirable feature of an abrasive holding layer in a fastening structure of the present invention; Fig. 4A shows a state of the abrasive holding layer before fastening and Fig. 4B shows a state of the abrasive holding layer after fastening.

Fig. S is an enlarged diagram of the periphery of an abrasive of Comparative Example 2 for comparison with the present invention.

Fig. 6 is an enlarged diagram of the periphery of an abrasive of Comparative Example 3 for comparison with the present invention.

Fig. 7 is an enlarged diagram of the periphery of an abrasive of Comparative Example 4 for comparison with the present invention.

As shown in Fig. 1, specifically, an abrasive contained in wax, etc., is applied to a surface of a first member 2 composed of metal, the surface being a side to which a second member 3 is mounted, and an abrasive holding layer 1 is thereby formed. Next, the surface of the first member 2 having the abrasive holding layer 1 is mounted to an upper side of the second member 3 such that the abrasive holding layer 1 is disposed therebetween, and the first and the second members 2 and 3 are fastened with an axial force bolt 4 and a nut 5, so that a fastening structure of the present invention is produced. As shown in Fig. 2, the abrasive holding layer l is composed of abrasive 11 and wax 12, etc., and is held between two members 13 and 14, and portions of the abrasive 11 are embedded in the respective surfaces of the two members 13 and 14 by the fastening.

In the fastening of the first and the second members, an abrasive holding layer of the present invention is required to be pressed in a surface direction by a load generated by the fastening, so that the thickness of the abrasive holding layer can be smaller than a diameter of the abrasive, and portions of the abrasive can be embedded in respective fastening surfaces of the first and the second members. The abrasive holding layer of the present invention is desirably formed by coating a material containing abrasive on the fastening surfaces of the first and the second members in order to arrange the abrasive uniformly. In the coating, an abrasive holding layer forming material is desirably in a liquid state by heating or adding solvent thereto. The abrasive holding layer forming material has more desirably a viscosity of 5 to 20 mm2/S from the points of view that the abrasive is unlikely to precipitate, is easy to apply with a brush, and is unlikely to drip. It is desirable that the abrasive holding layer forming material be able to harden at ordinary temperatures and that the abrasive can be held in an applied structure after coating. Rustproofing wax, etc., used on inner surfaces of an automobile, mainly pocket portions and connecting portions such as a door inside, a side sill, a cross member, and a hinge is used as the abrasive holding layer forming material. This wax is desirably dispersed in solvent at a wax component ratio of l to 50 %.

In the fastening structure of the present invention, in the case in which at least one of the first and the second members is penetrated by a fastening member and has a through hole having a hole diameter larger than an outside diameter of the fastening member, and in the case in which the first and the second members are made of sheet metal subjected to electrodeposition coating before the fastening, generation of noise and loosening of screw are remarkably prevented.

The abrasive of the fastening structure of the present invention is required to be harder than materials of the first and the second members since portions of the abrasive are embedded in the first and the second members made of metal.

It is desirable that the abrasive of the present invention be resistant to high temperatures, have large heat conductivity, have small thermal expansion coefficient, and be acid-resistant and alkali-resistant. The abrasive is desirably composed of a semiconductor from an electrical point of view. Specifically, it is desirable that the abrasive be composed of green silicon carbide crystal, crystalline grain composed of silicon carbide or boron carbide, or diamond grain.

The green silicon carbide crystal may be produced such that an ingot is made by reacting a silicon oxide material of high purity in an electric resistance furnace, is grinded, and is ground. The grain size of the abrasive is desirably #100 to mesh.

Another feature of the abrasive holding layer in the fastening structure of the present invention has a metallic washer, and abrasives disposed at both surfaces of the metallic washer via an adhesive. Specifically, as shown in Fig. 3, abrasives 24 harder than fastening base materials are adhered to surfaces of a metallic washer 23 on which electrodeposition coatings 21 and primer coatings 22 (corresponding to an adhesive) are formed, and then are baked on. As a result, an abrasive holding layer 25 of the fastening structure of the present invention is formed. Then, fastening is performed in a state in which the abrasive holding layer 25 of this feature is disposed between fastening base materials 27 which have electro deposition coatings 26 formed on surfaces thereof. As a result, since the hardness of the abrasive 24 is higher than the metallic washer and the fastening base materials, the abrasive 24 cuts into the metallic washer 23 and the fastening base materials 27 or deform the surfaces of the metallic washer 23 and the fastening base materials 27, so that the slipping resistances of the fastening surfaces are increased, and good slipping prevention effect can be obtained. The state of the abrasive 24 will be described hereinafter. In the state of the abrasive 24 before the fastening as shown in Fig. 4A, the abrasive 24 is disposed on the surface of the metallic washer 23 which has electrodeposition coating 21 and primer coating 22 formed on the surfaces thereof. In the state of the abrasive 24 after the fastening as shown in Fig. 4B, the abrasive 24 deforms the electrodeposition coating 21 and the primer coating 22, and cuts into the metallic washer 23, so that the slipping resistance is Increased.

EXAMPLES

Effects of the present invention will be described hereinafter with reference to a specific Example.

(l) Production of Fastening Structure

Example 1

An abrasive holding layer was formed such that crystalline grains of silicon carbide as an abrasive were contained in rustproofing wax, and the wax containing the grains was applied to a surface of a member corresponding to an automobile body as a first member, the surface being a side to which a second member was mounted. The wax is a product of PARKER INDUSTRIES CO., LTD., and the product name is "NOX-RUST HS700". The grains are a product of FLORA TRADE CO., LTD., and the product name is "green silicon carbide".

Next, as shown in Fig. 1, a sub-frame (second member) 3 for an automobile was secured at a jig, the surface of the body corresponding member (first member) 2 having the abrasive holding layer 1 is mounted to an upper side of the sub-frame (second member) 3 so that the abrasive holding layer 1 is disposed therebetween, and the first and second members 2 and 3 were fastened with an axial force bolt 4 and a nut 5 at a fastening force of 3,000 kgf. As a result, a fastening structure of Example 1 was produced. When the periphery of the abrasive of the fastening structure of Example 1 is viewed enlarged, as shown in Fig. 2, the abrasive holding layer composed of the abrasive 11 and the rustproofing wax 12 is held between the body corresponding member (first member) 13 and sub-frame (second member) 14, and portions of the abrasive 11 are embedded in the surfaces of the body corresponding member 13 and the sub-frame l 4 by the fastening.

Comparative Example 1 A fastening structure of Comparative Example l was produced in the same manner as in Example l, except that no abrasive holding layer containing the abrasive was provided.

Comparative Example 2 An abrasive holding layer was formed such that crystalline grains of silicon carbide as an abrasive were contained in rustproofing wax, and the wax containing the grains was applied to a surface of a member corresponding to an automobile body as a first member, the surface being a side to which a second member was mounted. The wax is a product of PARKER INDUSTRIES CO., LTD., and the product name is "NOXRUST 700". The grains are a product of FLORA TRADE CO., LTD., and the product name is "green silicon carbide".

The following processes were executed in the same manner as in Example 1.

As a result, a fastening structure of Comparative Example 2 was produced.

When the periphery of the abrasive of the fastening structure of Comparative Example 2 is viewed enlarged, as shown in Fig. 5, the abrasive holding layer composed of the abrasive 11 and the rustproofing wax 15 is held between the body corresponding member (first member) 13 and the sub-frame (second member) 14. However, since the abrasive holding layer is strong, even in fastening the body corresponding member 13 and the sub-frame 14, the abrasive is secured in the anti-corrosive wax 15, and does not contact the surfaces of the body corresponding member 13 and the sub-frame 14.

Comparative Example 3 An adhesive was applied to a surface of a member corresponding to an automobile body as a first member, the surface being a side to which a second member was mounted. Crystalline grains of silicon carbide as an abrasive were sprayed on the surface to which the adhesive was applied, so that the abrasive was secured on the surface of the body corresponding member (first member) 13. The adhesive is a product of Tombow Pencil CO., LTD., and the product name was "stick paste". The grains are a product of FLORA TRADE CO., LTD., and the product name is "green silicon carbide". The following processes were executed in the same manner as in Example 1. As a result, a fastening structure of Comparative Example 3 was produced. When the periphery of the abrasive of the fastening structure of Comparative Example 3 is viewed enlarged, as shown in Fig. 6, the abrasive 11 is held between the body corresponding member (first member) 13 and the sub-frame (second member) 14. In this case, an adhesive 16 is disposed between the abrasive 11 and the body corresponding member 13. A portion of the abrasive 11 is embedded in only the surface of the sub-frame 14 by the fastening.

Comparative Example 4 A double-sided tape was applied on a surface of a member corresponding to an automobile body as a first member, the surface being a side to which a second member was mounted. Crystalline grains of silicon carbide as an abrasive were sprayed on the surface on which the double-sided tape was applied, so that the abrasive was secured on the surface of the body corresponding body (first member) 13. The doublesided tape is a product of NITTO DENKO CORPORATION, and the product name is "double-coated adhesive tape". The grains are a product of FLORA TRADE CO., LTD., and the product name is "green silicon carbide". The following processes were executed in the same manner as in Example 1. As a result, a fastening structure of Comparative Example 4 was produced. When the periphery of the abrasive of the fastening structure of Comparative Example 4 is viewed enlarged, as shown in Fig. 7, the abrasive 11 is held between the body corresponding member (first member) 13 and the sub-frame (second member) 14. In this case, double-sided tape 19 having a base material 17 and adhesives l 8 disposed on both surfaces thereof are disposed between the abrasive 11 and the body corresponding member 13. A portion of the abrasive l l is embedded in only the surface of the subframe 14 by the fastening.

(2) Evaluation of Fastening Structure In the fastening structures of Example 1 and Comparative Examples 1 to 4, the second member 3 (sub-frame 14) was secured, load was gradually applied to the first member 2 (body corresponding member 13), and load F was measured when the first member 2 (body corresponding member l 3) started slipping.

The friction coefficients were calculated by the relationship of (load F/fastening force (=3,000 kgf)), the ratios of Example and Comparative Examples to Comparative Example 1 in which two members were directly fastened were calculated, and slipping prevention effects were thereby evaluated. The results thereof were shown in Table 1.

Table 1

Comparative Comparative Comparative Comparative Exampic 1 ExampIc I Example 2 Example 3 Example 4 Ratio of 2.9 1.0 O.X 1 2.1 0.9 As shown in Table 1, in the fastening structure of Example l of the present invention, since portions of the abrasive 11 are embedded in the respective surfaces of the body corresponding member 13 and the sub-frane 14 by the fastening, the friction coefficient between the two members was increased to be 2.9 times as large as that of Comparative Example 1, so that it was confirmed that the slipping between the two members was inhibited, and generation of noise and loosening of screws were prevented.

In contrast, in the fastening structure of Comparative Example 2, the abrasive was secured in the rustproofing wax 15 even in the fastening, and thereby did not contact the surfaces of the body corresponding member l 3 and the sub-frame 14. In the fastening structures of Comparative Example 3 and 4, since the adhesive 16 and the double-sided tape 19 are provided to secure the abrasive 1 l, the portion of the abrasive 11 is embedded in only the surface of the sub-frame 14 by the fastening. Due to this, it was shown that in the fastening structures of Comparative Examples 2 to 4 sufficient coefficients could not be obtained.

Claims

Claims: 1. A fastening structure comprising: a first member composed of

metal and having a fastening surface; a second member composed of metal and having a fastening surface, a fastening member for fastening the first member and the second member in a state in which the fastening surface of the second member is adjacent the fastening surface of the first member; and an abrasive holding layer formed between the first member and the second member, the abrasive holding layer containing an abrasive, wherein in fastening the first member and the second member, portions of the abrasive are embedded in the fastening surfaces, and the abrasive is held by the first member and the second member.
2. A fastening structure as claimed in claim 1, wherein the first member and the second member are composed of sheet metal subjected to electrodeposition coating before the fastening.
3. A fastening structure as claimed in claim 1 or claim 2, wherein the abrasive is selected from a group consisting of green silicon carbide, crystalline grains composed of silicon carbide and boron carbide, and crystalline grains of diamond.
4. A fastening structure as claimed in claim 1, 2 or 3, wherein the abrasive holding layer is formed by applying rustproofing wax in which the abrasive is contained.
5. A fastening structure as claimed in claim 1, 2 or 3, wherein the abrasive holding layer comprises: a washer composed of metal; abrasives disposed on the both surfaces of the washer; and adhesives disposed among the washer and the abrasives.
6. A fastening structure substantially as hereinbefore described with reference to figures 1 and 2 or figures 1, 3 and 4.