JP2009052602A - Rust prevention structure of bolt tightening part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rustproof structure of a bolt tightening part, securing film thickness of a rust preventive paint to a pointed part such as the tip of a pin part or a screw thread of a pin tail broken-out section to prevent generation of rust due to an insufficient film thickness, and dispensing with a rustproof cap to prevent generation of rust due to too much or too little rustproof agent filling the rustproof cap. <P>SOLUTION: In the state where an additional nut 4 is added to a screw shaft part (a surplus length part of a screw shaft part b) of a toque shear type high strength bolt 1 projected from a nut 2, thereby forming a recessed part C between the pin tail broken-out section S1 and the tip end face S2 of the additional nut 4, rustproof coating is performed. Previously, an anaerobic adhesive is applied to a screw hole of the additional nut 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rust prevention measure for a bolt fastening portion used for joining, for example, a steel beam member or a column member.

  One method of joining steel beam members and column members is friction joining using high-strength bolts. In many cases, Torcia type high-strength bolts are used for this joining method. The torcia type high strength bolt has a round head and a pin tail that receives the reaction force of the tightening wrench at the tip of the bolt (tip of the screw shaft). One bolt, one nut, and one washer. It is used as a set, and it is a mechanism that can confirm that the required axial force has been introduced by breaking the pin tail by tightening the nut to the bolt.

  When using this Torcia type high strength bolt exposed to the outdoors (for example, joining steel structures in outdoor facilities such as bridges and stations), to prevent rusting of bolt fastening parts, A rust preventive cap 7 made of aluminum or resin in which a facing portion is coated with a rust preventive or a filler 6a such as a water stop material or a rust preventive material is filled from above the nut 2 as shown in FIG. It is common to take measures such as covering with a rust-proof coating.

However, direct, when subjected to anti-rust paint on bolts and nuts, the film thickness of the anticorrosive coating 5 is not easily secured against sites pointed to the tip of the pointed portion and threads of pintail fracture surface S ₁ Rust may occur from these parts due to insufficient film thickness. When the rust prevention cap 7 is used, the filler 6a filled in the rust prevention cap 7 may be excessive or insufficient. When the amount of the filler 6a is small, an air layer remains inside the rust prevention cap 7 and rusts. If there is a large amount of filler 6a, the rust prevention cap 7 will rise, and the interface between the bolted steel frame and the rust prevention cap 7 will be a weak point in rust prevention, and rust may be generated from this part. There is sex.

  In Patent Document 1, even when the upper bolt is cut and removed from the double nut, it is possible to attach a rust prevention container (a member corresponding to the above-described rust prevention cap) including a cylindrical cover and a lid member. An attachment for a rust-proof container for a bolt fastening portion which is made possible is described. This fixture is composed of a cylindrical threaded member arranged on the upper nut of the double nut, and a hexagonal nut restraining member having a transverse cross section for fixing the threaded member to the upper nut. .

  Then, the nut restraining member is fitted into the upper nut, and the claw portion formed at the lower end of the nut restraining member is locked to the lower end of the corner of the upper nut, while the threaded member is placed on the upper nut. In this state, the six locking claws extending above the nut restraining member are bent inward and inserted into the radial through-hole formed in the cylindrical wall portion of the threaded member to be locked. By locking the hook at the tip of the claw to the hole edge of the through hole, the threaded member is configured to be fixed to the upper nut.

  After that, in this state, the packing and the cylindrical cover of the rust prevention container are arranged around the double nut, and the inside of the cylindrical cover is filled with the rust preventive agent, and then the lid member of the rust prevention container is attached to the threaded member. The upper end opening of the cylindrical cover is closed, and the lower end opening of the cylindrical cover is pressed against the packing.

Therefore, according to the technique described in Patent Document 1, a large number of parts such as a threaded member, a nut restraining member, a packing, a cylindrical cover, and a lid member are required to realize the rust prevention structure of the bolt fastening portion. In addition, it is necessary to perform the troublesome work of bending the locking claw of the nut restraining member inward and inserting and locking the hook at the tip of the locking claw into the through hole of the threaded member. The fastening portion is a construction target, and there is a problem that it is difficult to implement the lateral bolt fastening portion.

  In Patent Document 2, bolts, nuts, and washers are covered with a heat-shielding material such as a paint-type heat insulating material (ceramic paint) or a heat-foaming-type fire-resistant paint, a metal cap, and the like. Describes a technique for improving the fire resistance performance of a part and realizing a steel structure with a fireproof coating at low cost.

  Although the invention described in Patent Document 2 is not a rust prevention structure for bolt fastening portions, even if this invention is applied to a rust prevention structure for bolt fastening portions, a rust prevention coating is directly applied to bolts, nuts and washers. If it is applied, it is difficult to secure the film thickness of the anticorrosive paint on the sharp part such as the sharp part of the pin tail fracture surface and the tip of the screw thread, and the metal cap is filled with filler and the nut In the case of fitting in the case, as in the conventional example of FIG.

  Patent Document 3 describes a rust preventive tool that rusts an exposed portion of an existing anchor bolt or existing reinforcing bar exposed from the concrete surface over a long period of time, and that can be easily attached to and removed from the exposed portion. This rust prevention tool is filled with a liquid rust preventive agent inside a bottomed cylindrical resin cap with a polygonal cross-section locking projection that serves as a hook for a wrench or spanner on the outer surface of the end. The sealed bag body is stored, and the cap part is pressed into the exposed part such as an existing anchor bolt, and the cap part is pressed in the axial direction to rupture the sealed bag body, thereby preventing liquid rust. It is comprised so that an agent may be apply | coated to exposed parts, such as an existing anchor bolt.

  Even if the invention described in Patent Document 3 is applied to the rust prevention structure of the bolt fastening portion, it is the same as the conventional example in FIG.

JP 2001-82433 A JP 2003-293475 A Utility Model Registration No. 3087474

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to provide a rust preventive paint for a sharp part such as a sharp part of a pintail fracture surface or a tip of a screw thread. Bolt fastening that can prevent rusting due to insufficient film thickness because it can secure the film thickness and prevent rusting due to insufficient film thickness, and because it does not use a rust prevention cap It is to provide a rust preventive structure of the part.

  The technical means taken by the present invention in order to achieve the above object are as follows. That is, the rust preventive structure of the bolt fastening portion according to the invention of claim 1 is a rust preventive paint for bolts and nuts in a state where a recess is formed between the front end surface of the screw shaft portion of the bolt and the front end surface of the nut. It is characterized by having done.

In the first aspect of the present invention, the rust-proof coating is applied to the recess formed between the tip surface of the bolt shaft and the tip surface of the nut. There are cases where the coating material itself is applied so that it accumulates to a predetermined thickness, and, as in the invention described in claim 2, after the concave portion is filled with the concave portion filling material, the bolts and nuts are subjected to anticorrosive coating. . The rust preventive paint used for the rust preventive coating is not particularly limited, but as in the invention according to claim 3, the rust preventive paint includes an undercoat material, an intermediate coat material and a top coat material, and the intermediate coat material is mainly composed of an acrylic copolymer. It is preferable that

  The rust prevention structure of the bolt fastening portion according to the invention of claim 4 is the rust prevention structure of the bolt fastening portion according to any one of claims 1 to 3, wherein the screw of the bolt protruded from the tip end surface of the nut. Another nut is added to the shaft portion, and a recess is formed between the tip surface of the screw shaft portion of the bolt and the tip surface of the added nut.

  The rust prevention structure of the bolt fastening portion according to the invention described in claim 5 is the rust prevention structure of the bolt fastening portion according to claim 4, and is added to the screw shaft portion of the bolt protruding from the tip end surface of the nut. An additional nut is screwed into the screw shaft portion in a state in which an adhesive is previously applied to at least one of the screw holes of the nut.

  The rust prevention structure of the bolt fastening portion according to the invention described in claim 6 is the rust prevention structure of the bolt fastening portion according to claim 5, characterized in that an anaerobic adhesive is used as the adhesive. .

  The rust prevention structure of the bolt fastening portion according to the invention of claim 7 is the rust prevention structure of the bolt fastening portion according to any one of claims 1 to 6, wherein the bolt is a high strength bolt. Yes.

  The rust prevention structure of the bolt fastening portion according to the invention described in claim 8 is the rust prevention structure of the bolt fastening portion according to claim 7, wherein a torcia type high strength bolt is used as the high strength bolt, and the tip of the nut Another nut is added to the screw shaft portion of the Torcia type high strength bolt protruding from the surface, and a recess is formed between the pintail fracture surface of the Torcia type high strength bolt and the end surface of the added nut. It is characterized by.

  According to the first aspect of the present invention, since the bolts and nuts are directly coated with rust without using the rust prevention cap, the rust prevention cap is filled like the rust prevention method using the rust prevention cap. There is no risk of rusting due to the excess or deficiency of the filler to be used, and the rust preventive coating of the bolts and nuts is performed with a recess formed between the tip surface of the bolt screw shaft and the nut tip surface. Since this is done, the recess becomes a paint reservoir and a space for filling.

  Therefore, even if the screw shaft portion of the bolt has a sharp portion such as a sharp portion of the pintail fracture surface or the tip of the thread, these do not protrude from the nut tip surface, and the anticorrosive paint in the recess In other words, the film thickness of the rust preventive paint can be secured even at a pointed portion, and rusting due to insufficient film thickness can be prevented.

  In particular, according to the invention described in claim 2, after filling the recess formed between the tip end surface of the screw shaft portion of the bolt and the tip end surface of the nut with the recess filling material, the rust preventive coating of the bolt and nut is performed. Therefore, a film of a rust preventive paint is applied on the concave filling material, and the rust preventive effect can be enhanced.

  According to invention of Claim 3, a rust prevention effect can be maintained over a long term. That is, a rust preventive paint using an intermediate coating material mainly composed of an acrylic copolymer is excellent in flexibility and weather resistance and maintains a rust preventive effect over a long period of time.

  According to the invention described in claim 4, another nut is added to the screw shaft portion of the bolt protruding from the tip surface of the nut, and the tip surface of the screw shaft portion of the bolt and the tip surface of the added nut Since the concave portion is formed between them, the exposed screw thread portion of the screw shaft portion protruding from the tip end surface of the nut can be eliminated, and the rust preventive structure according to claim 1 or 2 can be applied to the screw tip surface. The film thickness of the anticorrosion paint with respect to the thread tip can be secured.

  According to the fifth aspect of the present invention, the additional nut is screwed in a state where an adhesive is applied in advance to at least one of the screw shaft portion of the bolt projecting from the tip end surface of the nut and the screw hole of the nut to be added. Since it is screwed into the shaft part, the screw shaft part protruding from the end face of the tightening nut is bonded to the additional nut, preventing loosening or dropping of the bolt due to slight vibration during construction and use. .

  According to the invention described in claim 6, in the invention described in claim 5, an anaerobic adhesive is used as the adhesive to be applied in advance, so that the additional nut can be screwed lightly in a state where resistance by the adhesive is low. Regardless of this, the screw fitting part that comes in close contact with the screw is cut off from the outside air to generate a predetermined adhesive force, and the screw shaft part protruding from the end face of the tightening nut and the additional nut are bonded. Therefore, the bolts can be prevented from loosening or falling off due to slight vibration during construction and use.

  Note that claims 1 to 6 are for general bolts. According to the invention described in claim 7, it can be applied to a high-strength bolt.

  When a torcia type high strength bolt is used as a high strength bolt, when the pin tail breaks due to tightening of the nut, a sharp point is generated on the pin tail fracture surface. Although there is a possibility that the thickness cannot be secured, according to the invention of claim 8, the pintail fracture surface is recessed from the additional nut to form a recess, so that the recess can be used for paint accumulation or filling. It becomes a space.

  Therefore, the sharp part of the pin tail fracture surface is buried in the rust preventive paint and the concave filler in the concave part, and the film thickness of the rust preventive paint can be secured even for the sharp part, resulting from the insufficient film thickness. Rust can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show an example of a rust prevention structure of a bolt connecting portion according to the present invention. A and B are two steel members friction-joined using the Torcia type high strength bolt 1. 2 is a nut for tightening and 3 is a washer.

  As shown in FIG. 1, the torcia type high strength bolt 1 has a round head, and a pin tail c serving as a reaction force of a tightening wrench at a bolt tip (tip of a screw shaft portion b) has a breaking groove d. Is provided. Then, one bolt, one nut, and one washer are used as one set, and the pin tail c is broken as shown in FIG. 2 by tightening the nut 2 for tightening the bolt. It is comprised so that it can confirm that axial force was introduced.

  Further, as shown in FIG. 2, after the pin tail c is broken, the extra length portion of the screw shaft portion b is one screw thread or more from the tip surface S of the nut 2 for tightening (preferably 2 to 5 threads). Degree) is set to protrude.

After the pin tail c is broken by tightening the nut 2, as shown in FIG. 3, the pin tail breaks into the screw shaft portion (excess length portion of the screw shaft portion b) e of the bolt protruding from the tip surface S of the nut 2. has a thickness that section S ₁ is hidden, that is, screwed by adding nut 4 for additional threaded shaft portion is protruded a thicker axial length of the (surplus portions) e, torque shear-type high-strength bolts 1 A recess X is formed between the pin tail fracture surface S ₁ of the screw shaft portion b and the tip end surface S ₂ of the additional nut 4.

When the additional nut 4 is screwed into the screw shaft portion (extra length portion) e protruding from the nut 2 for tightening, the screw shaft portion (extra length portion) e and the screw hole of the additional nut 4 In addition, it is possible to prevent loosening or dropping off of the additional nut 4 due to slight vibration during construction and use, etc., by screwing the additional nut 4 with at least one of the adhesives applied in advance. Desirable (this is the same in all other embodiments described later). Further, as the adhesive, it is possible to use an anaerobic adhesive (adhesive whose adhesive strength is expressed or increased by being shielded from air), so that the additional nut 4 can be screwed in with less resistance due to the adhesive. This is desirable because it can be done lightly. As the anaerobic adhesive, for example, Arontite (registered trademark) manufactured by Toagosei Co., Ltd., LOCTITE (registered trademark) manufactured by Henkel Japan Co., Ltd., and the like are suitable.

In this embodiment, as shown in FIG. 4, with the above-mentioned recess X formed, bolts and nuts (Torsia-type high-strength bolts 1 and nuts 2 and 4) and two steels frictionally joined by them are made. Rust prevention coating of members A and B is performed. 5 is a rust preventive paint.

  As the rust preventive paint 5, a general rust preventive paint can be used, but a rust preventive paint provided with an undercoat material, an intermediate coat material and a top coat material is suitable. In particular, a rust preventive paint using an intermediate coating material containing an acrylic copolymer as a main component is preferable because it has excellent flexibility and weather resistance and maintains a rust preventive effect over a long period of time. As an acrylic copolymer, what contains 50 mass% or more of the alkyl (meth) acrylic acid ester unit whose carbon number of an alkyl group is 4-10 as a structural monomer unit is preferable. Examples of the alkyl (meth) acrylate ester having 4 to 10 carbon atoms in the alkyl group include n-butyl (meth) acrylate, iso-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meta ) Acrylate, 2-ethylhexyl (meth) acrylate, and the like. Alkyl (meth) acrylic acid ester whose alkyl group has less than 4 carbon atoms may have poor alkali resistance of the coating film, and alkyl (meth) acrylic acid ester whose alkyl group has more than 10 carbon atoms is mainly used. Then, the cold resistance (elongation at low temperature) of the coating film may be deteriorated. If it is less than 50% by mass, the flexibility, water resistance and alkali resistance of the coating film may be insufficient. The acrylic copolymer having excellent flexibility as described above is also called acrylic rubber.

  As an acrylic copolymer, what contains 90 mass% or less of alkyl (meth) acrylic acid ester units whose carbon number of an alkyl group is 4-10 as a structural monomer unit is preferable. When it exceeds 90 mass%, the strength of the coating film may be insufficient.

  The acrylic copolymer is a copolymer of a vinyl monomer other than an alkyl (meth) acrylic acid ester having 4 to 10 carbon atoms in an alkyl group (also referred to as other vinyl monomer). Also good. Examples of other vinyl monomers include styrene, acrylonitrile, (meth) acrylic acid, glycidyl methacrylate, N-methylol acrylamide, alkyl (meth) acrylic acid ester having 1 to 3 carbon atoms in the alkyl group, and vinylidene chloride. Can be mentioned.

  The intermediate coating material is preferably an aqueous emulsion, and preferably has a solid content of 30 to 70% by mass. The viscosity of the intermediate coating material is set according to the construction method, but is preferably 1000 to 5000 mPa · s.

The intermediate coating material may be a material to which a filler generally blended in a paint is added. Examples of fillers for paint include hydraulic materials such as silica sand, talc, calcium carbonate, kaolin, gypsum, diatomaceous earth, titanium oxide, ordinary portland cement, and alumina cement. These may be used alone or in combination of two or more. Can be used. A preferable blending ratio of the filler for paint is 100 to 300 parts by mass based on 100 parts by mass of the acrylic copolymer. If it is less than 100 parts by mass, it may not be able to sufficiently exert effects such as strengthening the coating film or improving the workability of the coating film, and if it exceeds 300 parts by mass, the coating film will not be sufficiently stretched or waterproof. It may become.

  The intermediate coating material may be added with a surfactant, a viscosity stabilizer, an antifoaming agent, a leveling agent, a thixotropic agent, a flame retardant, and the like as other additives.

  When the intermediate coating material is a curable composition, there is a one-component type or a two-component or more type, but a one-component type is preferable from the viewpoint of workability.

  When intermediate coating material is applied, polyester fiber, glass fiber, vinylon fiber, polyamide fiber, acrylic fiber, etc. on the undercoat material layer described later for the purpose of reinforcing the coating film in parts other than bolt and nut fastening parts It is also recommended that a woven fabric is laid.

  It is preferable that the primer is applied before the intermediate coating material is applied. The undercoat material has a function of improving the rust prevention function and the adhesion between the base and the intermediate coating material layer. Although what is generally used as an undercoat material can be used, an epoxy resin composition, a urethane resin composition, or the like in which a rust preventive pigment is blended is preferable. The standard dry film thickness (final film thickness) is 10 to 200 μm. It is also possible to employ a construction method in which a recess filler 6 described later is filled between the undercoat material and the intermediate coat material.

  It is preferable that the topcoat material is applied after the intermediate coating material is applied. The top coating material has a function of protecting the intermediate coating material layer and improving the design. Although what is generally used as a top coat material can be used, an acrylic resin, an acrylic urethane resin, an acrylic silicon resin, a fluororesin, etc. are used preferably. A composition that forms a film having an elongation at 50 ° C. of 50 to 500% is preferably used. The standard dry film thickness is 50-300 μm.

  As the rust preventive paint 5 used for the rust preventive coating of the present invention, it is preferable to include the undercoat material, the intermediate coat material, and the top coat material, and the standard dry film thickness as a whole is 100 to 5000 μm. Each coating material may be applied with a brush, a roller or the like, or may be applied by spraying. It is also preferable to apply the intermediate coating material in advance to the portion where the coating thickness of the concave portion or the convex portion is likely to be thin, after applying the undercoat material and before the intermediate coating step.

According to the above configuration, the bolts and nuts are coated directly on the rust and bolts without using the rust prevention cap. no risk of rusting due to excess or deficiency, yet, a recess X between the front end surface S ₂ of the nut 4 for adding and pintail fracture surface S ₁ of the screw shaft portion b of the torque shear-type high-strength bolts 1 In this state, since the bolt fastening portion is subjected to rust-proof coating, the concave portion X becomes a paint reservoir, and the thickness of the rust-proof paint 5 is thicker above the concave portion X than other portions.

Therefore, even if sharp region as the tip of the pointed portion and threads caused by breaks pintail fracture surface S ₁ of the torque shear-type high strength bolt 1, from the tip surface of the nut 4 for these additional protrusion Therefore, since the film is buried in the rust preventive paint 5 in the recess X, the film thickness of the rust preventive paint 5 can be secured even at a pointed portion, and rusting due to insufficient film thickness can be prevented.

  The shape of the additional nut 4 is not particularly limited. For example, it may have a shape like a bowl typified by a hemisphere, and in this case, it is difficult to make uneven the thickness of the coating film to be rust-proofed, so that a more excellent rust-proof function can be expected. Further, the additional nut 4 is not limited to steel as long as it can be applied with the above-described rust preventive paint 5, and may be, for example, a metal other than iron such as aluminum, ceramic, or synthetic resin.

  FIG. 5 shows another embodiment of the present invention, which is characterized in that after the concave portion X is filled with the concave portion filler 6, the bolt fastening portion is subjected to rust prevention coating. The process until the recess X is formed is the same as the process from FIG. 1 to FIG. 3 in the above-described embodiment.

  As the concave filling material 6, when the concave X is deep, a solvent-free type that does not substantially contain a volatile component such as an organic solvent or water is preferable. This is because if a volatile component is contained, the coating film formed by applying the rust preventive paint 5 in a later step may be floated or cracked. When the recessed part X is shallow, volatile components, such as an organic solvent and water, may be contained. The concave filling material 6 is not particularly limited as long as it is a curable material, but examples thereof include materials generally used as a sealing material, epoxy resin, and acrylic rubber.

According to this configuration, the recess filling material 6 is filled in the recess X formed between the pintail fracture surface S ₁ of the threaded shaft portion 1 b of the Torcia type high-strength bolt 1 and the tip surface S ₂ of the additional nut 4. Then, since the rust preventive coating of the bolt fastening portion is performed, a film of the rust preventive paint 5 is formed on the concave filling material 6, and the rust preventive effect can be enhanced. Since other configurations and operations are the same as those in the embodiment of FIGS. 1 to 4, the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 6 shows another embodiment of the present invention. In this embodiment, as a high-strength bolt that frictionally joins the steel members A and B, instead of the Torcia-type high-strength bolt 1, the head a is a hexagon, one bolt, one nut, and two washers. A high-strength hexagon bolt 1a used as one set is used. Then, another additional nut 4 is screwed into the screw shaft portion (extra length portion of the screw shaft portion b) e of the high-strength hexagon bolt 1a protruding from the tip surface S of the nut 2 for tightening. in a state in which a recess X between the front end surface S ₂ of the nut 4 for adding and tip surface S ₀ of the screw shaft portion b of the hexagonal bolt 1a, bolts and nuts (High Strength hex bolts 1a and nuts 2,4 ) And two steel members A and B which are friction-joined by them.

In the bolt fastening portions with high strength hex bolts 1a, since the pintail breaking step such as torque shear-type high strength bolt 1 is not present, it pointed portion such as pintail fracture surface on the distal end surface S ₀ of the screw shaft portion b is Although it does not occur, the film thickness of the anticorrosive paint on the thread tip of the screw shaft portion (excess length portion of the screw shaft portion b) e protruding from the nut 2 for tightening is insufficient only by applying the antirust coating. there's a possibility that. In this regard, according to the above configuration, another nut 4 is screwed into the screw shaft portion (excess length portion of the screw shaft portion b) e protruding from the nut 2 of the high-strength hexagon bolt 1a, and the high-strength hexagon in a state in which a recess X between the front end surface S ₀ of the screw shaft portion b of the bolt 1a the front end surface S ₂ of the nut 4 for additional, since doing anticorrosive paint bolt fastening portion, the concave portion X Becomes a paint reservoir, and the film thickness of the rust preventive paint 5 is thicker than the other parts above the recess X.

Therefore, does not protrude from the tip surface S ₂ of the nut 4 of the tip of the thread of e is added (extra length portion of the threaded shank b) a threaded shaft portion protruding from the nut 2 of high strength hex bolts 1a, the recess Since it is buried in the rust-proof paint 5 in X, the film thickness of the rust-proof paint 5 can be secured even at the tip of the screw thread of the screw shaft portion e, and rusting due to insufficient film thickness is prevented. it can. In addition, since the bolts and nuts are painted directly on the bolts and nuts without using the rust prevention cap, it is caused by excess or deficiency of the rust inhibitor filling the rust prevention cap as in the rust prevention method using the rust prevention cap. There is no risk of rusting.

  FIG. 7 shows another embodiment of the present invention, which is characterized in that after the recess X in FIG. 6 described above is filled with the recess filler 6, the bolts and nuts are rust-proofed.

According to this configuration, the concave portion X formed between the front end surface S ₂ of the nut 4 for adding and tip surface S ₀ of the screw shaft portion b of the high-strength hex bolts 1a, after filling the recess filler 6 Since the rust preventive coating of the bolt fastening portion is performed, a film of the rust preventive coating 5 is formed on the concave filling material 6, and the rust preventive effect can be enhanced. Since other configurations and operations are the same as those of the embodiment of FIG. 6, the same reference numerals are given to the same structural members, and description thereof is omitted.

8 and 9 each show another embodiment of the present invention. In these embodiments, instead of forming the recess X by screwing the additional nut 4 in FIG. 6 and FIG. 7 described above, the nut 2 for screwing into the high-strength hexagon bolt 1a is friction-joined. Using the nut 2 that is thicker than the axial length of the screw shaft portion protruding from the steel members A and B, the tip surface S ₀ of the screw shaft portion b of the high-strength hexagon bolt 1 a is recessed from the tip surface S of the nut 2. This is characterized in that the recess X is formed.

  In the former embodiment of FIG. 8 and the embodiment of FIG. 9, in the former, the concave portion X is formed as a paint reservoir by performing rust prevention coating of the bolt and nut in the state where the concave portion X is formed. The latter is different only in that anti-rust coating of bolts and nuts is performed after the recess X is filled with the recess filling material 6.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to embodiment mentioned above, For example, it is tension | tensile_strength rather than high strength bolts, such as the torcia type high strength bolt 1 and the high strength hexagon bolt 1a. Needless to say, the present invention can be implemented in various modes within a range not departing from the gist of the present invention, such as a rust prevention structure of a bolt fastening portion using a general bolt having a small force.

  Next, an Example and a comparative example are given and this invention is demonstrated more concretely. In addition, confirmation of the antirust performance in the following examples and comparative examples was performed by a cast test (CASS) method defined in JIS Z 2371 (salt water spray test method).

[Example 1]
One-side bolts and nuts were attached to plate members in which 6 mm and 9 mm thick steel plates were combined. Furthermore, another nut was added to the screw shaft portion of the bolt protruding from the tip surface of the nut. Primer [Aron MD Antirust Primer, Toagosei Co., Ltd.] 0.1 kg / m ² was applied to the recess between the tip surface of the screw shaft portion of the bolt and the tip surface of the added nut. On the next day, the recess was filled with a two-component reaction-curing epoxy resin adhesive [Bond Quick Set, Toagosei Co., Ltd.] to obtain a smooth surface matched to the upper end surface of the nut. Next, after applying anti-corrosion paint [epoxy resin base coat (about 100 μm), epoxy resin intermediate coat (about 30 μm) and polyurethane resin top coat (about 30 μm)], curing for 7 days (23 ° C.) A test specimen was prepared.
When a cast test was performed on the specimen after curing, no rusting was observed even after 2000 hours.

[Example 2]
One-side bolts and nuts were attached to plate members in which 6 mm and 9 mm thick steel plates were combined. Furthermore, another nut was added to the screw shaft portion of the bolt protruding from the tip surface of the nut. Primer [Aron MD antirust primer, Toagosei Co., Ltd.] 0.1 kg / m ² was applied to the entire surface including the recess between the tip surface of the screw shaft portion of the bolt and the tip surface of the added nut. The next day, a non-bleed type one-component polyurethane sealing material [Aron Sealant PU-1, Toagosei Co., Ltd.] was filled in the recesses to obtain a smooth surface in accordance with the upper end surface of the nut. Next, an acrylic rubber-based intermediate coating material [acrylic rubber-based composition (Aron Coat ST, 2.0 kg / m ² ) and weak solvent type acrylic silicon resin-based top coating material (Aron MD color Si, 0.3 kg / m ² ), All were cured for 7 days (23 ° C.) after applying Toagosei Co., Ltd.] to prepare test specimens.
When a cast test was performed on the test specimen after curing, no rusting was observed even after 3000 hours.

[Example 3]
One-side bolts and nuts were attached to plate members in which 6 mm and 9 mm thick steel plates were combined. Furthermore, another nut was added to the screw shaft portion of the bolt protruding from the tip surface of the nut. Primer [Aron MD antirust primer, Toagosei Co., Ltd.] 0.1 kg / m ² was applied to the entire surface including the recess between the tip surface of the screw shaft portion of the bolt and the tip surface of the added nut. The next day, the recess was filled with an acrylic rubber-based composition [Aron Coat ST, Toagosei Co., Ltd.] to obtain a smooth surface matched to the upper end surface of the nut. Next, an acrylic rubber-based intermediate coating material [acrylic rubber-based composition (Aron Coat ST, 2.0 kg / m ² ) and weak solvent type acrylic silicon resin-based top coating material (Aron MD color Si, 0.3 kg / m ² ), All were cured for 7 days (23 ° C.) after applying Toagosei Co., Ltd.] to prepare test specimens.
When a cast test was performed on the test specimen after curing, no rusting was observed even after 3000 hours.

[Comparative Example 1]
One-side bolts and nuts were attached to a plate member in which 6 mm and 9 mm thick steel plates were combined (a state in which the tip of the screw shaft portion of the bolt protruded from the nut). Next, after applying anti-corrosion paint [epoxy resin base coat (about 100 μm), epoxy resin intermediate coat (about 30 μm) and polyurethane resin top coat (about 30 μm)], curing for 7 days (23 ° C.) A test specimen was prepared.
When a cast test was performed on the test specimen after curing, rusting occurred from the threaded portion of the bolt after 24 hours.

[Comparative Example 2]
One-side bolts and nuts were attached to plate members in which 6 mm and 9 mm thick steel plates were combined. Furthermore, another nut was added to the screw shaft portion of the bolt protruding from the tip surface of the nut. Nothing was filled in the recess between the tip surface of the screw shaft portion of the bolt and the tip surface of the added nut. Next, after applying anti-corrosion paint [epoxy resin base coat (about 100 μm), epoxy resin intermediate coat (about 30 μm) and polyurethane resin top coat (about 30 μm)], curing for 7 days (23 ° C.) A test specimen was prepared.
When a cast test was performed on the test specimen after curing, rusting occurred from the thread portion of the nut after 24 hours.

The following table shows the test results of Examples 1 to 3 and Comparative Examples 1 and 2 described above.

It is sectional drawing which shows one Embodiment of this invention and demonstrates the state before a pin tail fracture | rupture. It is sectional drawing explaining the state after a pin tail fracture | rupture. It is sectional drawing explaining the state which added the nut and formed the recessed part. It is sectional drawing explaining the state which the antirust coating was completed. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing explaining a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torcia type high strength bolt 1a High strength hexagon bolt 2 Nut for tightening 3 Washer 4 Additional nut 5 Anticorrosive paint 6 Recessed filler 7 Anticorrosion cap a Head b Screw shaft part c Pin tail d Breaking groove e Tightening Screw shaft part protruding from the nut 2 for insertion (excess length part of the screw shaft part b)
A, B Steel member S Tip surface of nut 2 for tightening S ₀ Tip surface of screw shaft portion b of high-strength hexagon bolt 1a S ₁ Pintail fracture surface S ₂ Tip surface of nut 4 for addition X Recess

Claims (8)

  A rust preventive structure for a bolt fastening portion, wherein a rust preventive coating is applied to the bolt and nut in a state where a recess is formed between the tip end surface of the screw shaft portion of the bolt and the tip end surface of the nut.   2. The rust prevention structure for a bolt fastening portion according to claim 1, wherein the bolt and nut are coated with a rust prevention coating in a state in which the concave portion is filled with the concave filling material. Construction.   The rust preventive structure of the bolt fastening part according to claim 1 or 2, wherein the rust preventive paint used for the rust preventive coating includes an undercoat material, an intermediate coat material and an overcoat material, and the intermediate coat material is an acrylic copolymer. A rust preventive structure for a bolt fastening portion characterized by comprising a main component.   It is a rust prevention structure of the bolt fastening part in any one of Claims 1-3, Comprising: Another nut is added to the screw shaft part of the bolt protruded from the front end surface of the nut, and the screw shaft part of the bolt Rust prevention of a bolt fastening part characterized by forming a crevice between a tip surface and a tip surface of an added nut.   5. The rust prevention structure for a bolt fastening portion according to claim 4, wherein an adhesive is applied in advance to at least one of a screw shaft portion of a bolt projecting from a tip end surface of the nut and a screw hole of the nut to be added. The rust prevention structure of the bolt fastening portion is characterized in that the nut to be added is screwed into the screw shaft portion.   6. The rust prevention structure for a bolt fastening portion according to claim 5, wherein an anaerobic adhesive is used as an adhesive.   7. A rust preventive structure for a bolt fastening portion according to claim 1, wherein the bolt is a high strength bolt.   8. The rust prevention structure for a bolt fastening portion according to claim 7, wherein a torcia type high strength bolt is used as the high strength bolt, and another screw shaft portion of the torcia type high strength bolt protruded from the tip end surface of the nut is provided. A rust prevention structure for a bolt fastening portion, wherein a recess is formed between a pintail fracture surface of a screw shaft portion of a torcia type high-strength bolt and a tip end surface of the added nut by adding a nut.

Images