JP2002339938A - Fastening structure of resin coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening structure capable of superiorly fastening a member having a low-compression-rigidity resin coating layer to the surface of a resin coating flange etc. SOLUTION: This fastening structure is so constituted that, when resin coating flanges 4 and 4 are fastened using a bolt 7 and nut 9, a conical spring washer 11 is disposed with the side of its recess surface 11a directly contacting with the resin coating layer 5 and its outer circumferential part firmly pushing the opposed resin coating layer 5 so as to prevent the resin in its inside from flowing out the circumference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening structure for fastening two members, at least one of which is a resin coating material, using a screwing means such as a bolt or a nut. In this regard, the present invention relates to a fastening structure suitable for use in joining resin-coated flanges of pipe ends to each other.

[0002]

2. Description of the Related Art Conventionally, resin-coated steel pipes in which the inner surface of a pipe is coated with a resin such as polyethylene are widely used as piping materials in order to improve corrosion resistance, rust resistance, chemical resistance, and the like. And recently, in order to further improve anticorrosion,
BACKGROUND ART Resin-coated steel pipes having inner and outer surfaces in which a resin coating is applied to the entire surface of a pipe material including not only the inner surface of the tube but also the outer surface of the tube, the surface of the flange, and the like have been developed.

[0003]

However, it has been found that such a resin-coated steel pipe on the inner and outer surfaces causes a problem when the flanges are joined to each other on the pipe. That is, as shown in FIG. 3A, the resin coating layer 3 is formed on the inner and outer surfaces of the tube 2 and the resin coating layer 5 is also formed on the entire surface of the flange 4 joined to the tube end. In order to connect the outer resin-coated tubes 1, 1, the flanges 4, 4 are butted with a packing 6 therebetween, and bolts 7 having bolt heads 7 a, flat washers 8, 8, and nuts 9 are attached as shown in FIG.
When the bolts 7 and nuts 9 are tightened by a torque wrench with a predetermined tightening torque (the tightening torque employed when tightening the metal flange), the flat washers 8, 8 come into contact when the tightening torque is high. Portion of the resin coating layer 5 is compressed and deformed beyond the elastic region, and
After tightening, even though the bolts and nuts are not rotating in the loosening direction, they become loose in a very short time,
For this reason, retightening may need to be performed four to five times. In addition, despite the retightening performed a plurality of times to achieve a predetermined tightening torque, a sufficient sealing effect was not obtained, and therefore the tightening torque had to be increased. Here, the reason that the nut is loosened in a short time after the nut is tightened is that the resin in the portion of the resin coating layer 5 supporting the flat washer 8 receives the compressive force and flows around to generate deformation such as creep. It seems to be because. Actually, when the tightened portions of the bolt 7 and the nut 9 were observed, FIG.
As shown in (b), the flat washers 8, 8 are considerably sunk into the resin coating layer 3, and more specifically, a washer mark (indentation) of more than half the thickness of the resin coating layer 3. In some cases, the resin in this portion flows around and rises.

[0004] The present invention has been made in view of the above-mentioned problems, and is a method of fastening two members, at least one of which is a resin coating material, such as bolts and nuts, such as when fastening a resin coating flange. When concluding using
An object of the present invention is to provide a fastening structure of a resin covering material that minimizes a member used for fastening into a resin coating layer and enables excellent fastening of two members.

[0005]

Means for Solving the Problems The present inventors have intensively studied a structure capable of preventing a washer, a bolt head, a nut and the like from being fitted into a resin coating layer when fastening a resin coating material. It was found that by arranging the concavity side directly in contact with the resin surface of the resin coating material, it is possible to suppress the indentation of the disc spring washer into the resin coating layer and to perform good tightening. Completed the invention. That is, the present invention provides a fastening structure for fastening two members, at least one of which is a resin-coated material, using a screwing means such as a nut or a nut. A disc spring washer is arranged between the nuts such that the concave side thereof is in direct contact with the resin coating layer of the resin coating material. Here, the reason why the use of the disc spring washer reduces the intrusion into the resin coating layer and achieves good fastening is considered as follows. That is, when the concave surface side of the disc spring washer is pressed directly against the resin coating layer to perform fastening, almost the entire surface of the disc spring washer is pressed against the resin coating layer. It will be pressed most strongly against the resin coating layer. When the inner resin coating layer is pushed by the disc spring washer and flows around, the annular portion strongly pressed at the outer peripheral portion of the disc spring washer attempts to prevent the resin from flowing. For this reason, the apparent rigidity of the portion of the resin coating layer that supports the disc spring washer is increased, the sinking of the disc spring washer is reduced, and good fastening is ensured.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It is sufficient that at least one of the two members is a resin-coated material, as long as the two members are fastened using screwing means such as bolts and nuts. Therefore, the two members may be both resin-coated materials. May be a resin coating material, and the other may be a material without a resin coating, for example, only a steel material. Further, the resin coating material that is the object of the present invention is not limited to the one having a resin coating layer on the entire surface, and may include a resin surface on a side facing a fastening member such as a bolt head, a nut, and a washer. included. As a typical example to which the fastening structure of the present invention is applied, a resin-coated flange having a resin-coated layer formed on the entire surface of the flange can be cited.

[0007] The form of the screwing means such as bolts and nuts used in the fastening structure is determined from one side of the two members to be fastened.
It is common to penetrate a bolt with a bolt head and tighten a nut on the opposite side.However, the invention is not limited to this.A bolt is fixed to one of two members to be fastened, and the bolt is attached to the other member. Penetrate and fix with nuts, or form a threaded hole in one of the two members to be fastened, pass a bolt through the other member and screw into the threaded hole, etc.
It can be changed as appropriate.

[0008]

Embodiments shown in the drawings will be described below. FIG.
1 is a schematic sectional view of a fastening structure according to an embodiment of the present invention applied when fastening resin-coated flanges of inner and outer resin-coated tubes, and reference numerals 1 and 1 denote resin-coated tubes to be connected to each other. In this resin-coated tube 1, a resin-coated layer 3 is formed on the inner and outer surfaces of a metal tube 2 such as a steel tube, and a resin-coated layer 5 is formed on the entire surface of a metal flange 4 of steel or the like joined to the end of the tube. It is of a formed structure. The fastening structure for joining the flanges 4, 4 includes disc springs 11, 11 in addition to the bolt 7 having the bolt head 7 a, the flat washers 8, 8, and the nut 9.

The disc spring washers 11, 11 have been conventionally used to prevent loosening of bolts, nuts and the like, but what is conventionally arranged between a bolt head or a nut and a flat washer is as follows. In contrast, in the present embodiment, as shown in an enlarged manner in FIG.
And between the other flange 4 and the nut 9 such that the concave surface 11 a side is in direct contact with the resin coating layer 3. In this state, by tightening the nut 9 to the bolt 7 with a predetermined torque, the two flanges 4 are fastened as shown in FIG. In the fastened state, the disc spring washers 11, 11 are elastically deformed to a substantially flat state by being sandwiched between the bolt head 7a and the resin coating layer 5, and between the nut 9 and the resin coating layer 5, and the bolt 7, the nut 9 and the flange are formed. A spring force acts between the flanges 4 and 4 to constantly apply a desired pressing force between the flanges 4 and 4. At this time, since the disc spring washers 11 are strongly pressed against the resin coating layer 5, a large compressive force acts on a portion of the resin coating layer 5 that comes into contact with the disc spring washer 11, and the resin in that portion is hardened. The outer peripheral portion of the disc spring washer 11 is strongly pressed against the resin surface to prevent the resin inside from flowing around. As a result, the apparent rigidity of the portion of the resin coating layer 5 that supports the disc spring washer increases, and the sinking of the disc spring washer decreases. Thus, the amount of loosening of the nut 9 after tightening the nut 9 with a predetermined torque is reduced, so that it is not necessary to perform excessive tightening, and the sealing performance between the flanges 4 can be improved.

Next, results of a water pressure test performed by actually performing a flange tightening operation will be described. [Example 1] A steel pipe with a flange diameter (resin coating layer thickness: 1.5 mm) having inner and outer polyethylene powder coatings with a pipe diameter of 700 A is prepared, and the flanges are equally spaced in the circumferential direction.
As shown in FIGS. 1 and 2, a bolt 7, a flat washer 8,
It was fastened using a nut 9 and a disc spring washer 11. The bolt 7 and nut 9 used here have a nominal diameter of M30 and a material of SUS.
304, flat washer 8 is nominal diameter M30, outer diameter 50 mm, inner diameter 31 mm, thickness 4 mm, material SUS304, disc spring washer 11 is nominal diameter M30, outer diameter 56 mm, inner diameter 31 m.
m, thickness 5 mm, height (height in the axial direction) 6.6 mm,
The material is SUS304. When tightening the bolts 7 and the nuts 9, the initial tightening torque was 36.4 kgfm with a torque wrench.
4) After tightening, the amount of loosening of the nut was measured.
As a result, the amount of looseness is 7 kgfm at maximum and 2 kgf at minimum.
m, average 3.3 kgfm. Next, retightening was performed, and tightening was performed again so that the tightening torque became 36.4 kgfm. After that, when a water pressure test was performed, no leak was observed between the flanges even when the water pressure in the pipe was set to 1.0 MPa, and good sealing was secured. After the completion of the water pressure test, the bolts and nuts were removed, and the state of the resin coating layer was observed. The depth of the washer trace was as small as about 0.3 mm.

Comparative Example 1 For comparison, a flange fastening operation was performed under the same conditions as in Example 1 except that no disc spring washer was used. At this time, the nut was tightened with a torque wrench to an initial tightening torque of 36.4 kgfm. After the tightening of all the nuts (24 pieces) was completed, the looseness of the nut was measured. 0.4 kgfm. After that, retightening was performed and the tightening torque was 36.4 kg again.
fm, but a considerable amount of loosening was observed again. Therefore, retightening was performed twice more, and finally, retightening was performed a total of four times. Thereafter, when a water pressure test was performed, a leak occurred between the flanges when the water pressure in the pipe exceeded 0.9 MPa, and thus the sealing performance was inferior to that of Example 1. After the completion of the water pressure test, the bolts and nuts were removed, and the state of the resin coating layer was observed.
About m washer marks were observed. The tightening torque required to withstand the water pressure in the pipe of 1.0 MPa was measured in the same manner as in Example 1 and found to be 42.0 kgfm.

As is clear from the first embodiment and the first comparative example, in the comparative example using no disc spring washer, the flat washer pushes out the resin coating layer facing the same when the bolt and nut are tightened. In order to dig into the resin coating layer, it was necessary to retighten a plurality of times, and even if the retightening was performed, sufficient sealing performance between the flanges could not be obtained. The washer prevents flow around the resin coating layer facing it, in other words, the portion of the resin coating layer facing the disc spring washer provides good support for the disc spring washer, thereby requiring less retightening. Without having to tighten bolts and nuts.
Good sealing performance between the flanges can be obtained.

[0013]

As is apparent from the above description, in the fastening structure of the present invention, when fastening the resin coating material, the disc spring washer is simply disposed so that the concave side thereof is in direct contact with the resin surface of the resin coating material. By adopting a simple structure, the conical spring washer is favorably supported by the resin coating layer having a small compression rigidity, the desired fastening strength can be secured, and the resin coating material can be fastened with a simple structure. ing. And
By applying the present invention to the joining of the resin-coated flanges of the inner and outer resin-coated tubes, the resin-coated flanges can be satisfactorily fastened to each other, and the effect of easily performing the piping of the inner and outer resin-coated tubes can be obtained. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a fastening structure according to an embodiment of the present invention.

2A is a schematic cross-sectional view showing the fastening structure of FIG. 1 before the nut is tightened, and FIG. 2B is a schematic cross-sectional view showing the fastening structure of FIG. 1 after the nut is tightened.

FIG. 3 (a) is a schematic cross-sectional view showing a normal fastening structure for fastening resin-coated flanges before fastening a nut, and FIG. 3 (b) shows a fastening structure shown in FIG. Schematic sectional view showing the state of

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inner and outer resin coated tube 2 tube 3 resin coated layer 4 flange 5 resin coated layer 6 packing 7 bolt 7 a bolt head 8 flat washer 9 nut 11 disc spring washer 11 a concave surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daisuke Hosaka 2-17-8 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Within Dai-ichi High Frequency Industry Co., Ltd. (72) Inventor Shigetoshi Otsuka 2-Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 17-8 Daiichi Kogyo Kogyo Co., Ltd. (72) Inventor Ryoji Kobayashi 2-17-8 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in Daiichi Kogyo Kogyo Co., Ltd. AA02 BB01 GA20 4F211 AD12 AD25 AG08 AG24 AH43 TA06 TC11 TD11 TN76

Claims (2)

[Claims] 1. A fastening structure for fastening two members, at least one of which is a resin coating material, using a screwing means such as a bolt or a nut, wherein the resin coating material and a bolt head or nut for applying a tightening force thereto. Wherein the conical spring washer is disposed such that the concave side thereof is in direct contact with the resin coating layer of the resin coating material. 2. The fastening structure for a resin-coated material according to claim 1, wherein the resin-coated material is a resin-coated flange.