JP2013224142A - Lightning-resistant fastener, aircraft and method of mounting lightning-resistant fastener - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightning-resistant fastener, a cap and a method of mounting the lightning-resistant fastener which reliably secures insulation properties, further, improves workability and quality stability and, moreover, can reduce a manufacturing cost of an air frame.SOLUTION: A cap made of an insulating material, in which an uncured insulating sealant is filled into an inner part thereof, is mounted to a fastener body 25 so as to cover the fastener body 25 and a collar 26 therewith. Thereby, the insulation property is reliably secured, moreover, the workability is improved to suppress a manufacturing cost and the cap 30 can be mounted with stable quality irrespective of workers.

Description

The present invention relates to a lightning-resistant fastener used for an aircraft fuselage, particularly a wing, an aircraft , and a method for attaching the lightning-resistant fastener.

A wing constituting an aircraft body has a hollow structure, and a wing surface panel forming a wing surface is fixed to a structural material inside the wing by a fastener member (fastener).
The fastener member is a pin-shaped fastener body that is inserted into a through-hole formed in both the wing and the member attached to the wing from the outside of the wing, and its tip is fixed with a fixing bracket from the inside of the wing. Then, the wing and the member are fastened.

  By the way, in an aircraft, it is necessary to take thorough countermeasures against lightning. When the wing surface panel and fastener member are made of different materials, arc discharge (spark) in the direction along the interface between the wing surface panel and the fastener member due to a potential difference between the wing surface panel and the fastener member during a lightning strike Will occur. Since a fuel tank is housed in the inner space of the wing, it is necessary to reliably suppress the occurrence of arc discharge during lightning strikes.

  Therefore, conventionally, as shown in FIG. 9, the fastener body of the fastener member 4 that penetrates the first member 2 corresponding to the blade surface panel and the second member 3 attached to the inside of the blade on the inner side of the blade 1. A structure has been proposed in which the cap 6 is attached in a state of being separated from the 4a and the fixing bracket 4b, and a gap 7 filled with air is formed between the fastener body 4a and the fixing bracket 4b (see, for example, Patent Document 1). ).

Japanese Patent Laid-Open No. 2-7398

However, the technique described in Patent Document 1 does not have a structure in which the cap 6 can be positioned with respect to the fastener member 4, and the mounting position of the cap 6 depends on the operator. For this reason, the center of the cap 6 and the center of the fastener member 4 may be largely shifted. If a space is formed in the gap 7 where the gap between the fastener member 4 and the cap 6 is small, the function (insulating property) of the cap 6 is deteriorated. In the worst case, if the cap 6 is attached in a state where it is in contact with the fastener member 4, the function of the cap 6 itself may be greatly impaired.
The cap 6 is attached to the second member 3 with an adhesive 9 as shown in FIG. 9A, or the outer periphery is covered with rubber (insulating material) 10 as shown in FIG. 9B. Therefore, it is necessary to perform bonding work and rubber 10 application work at the installation site, which is troublesome. Needless to say, the space inside the wing 1 of the aircraft is narrow, and it is very inefficient to perform the above-described work in a deep position. Moreover, since such fastener members 4 are provided on the entire blade 1 at several thousand to several tens of thousands, the deterioration in workability directly leads to an increase in cost.
Furthermore, the above-described operations are so-called manual operations, and the construction quality is likely to vary depending on the operator, which also affects the reliability.

  The present invention has been made on the basis of such a technical problem, and it is possible to improve the workability and the stability of the quality while ensuring the insulation, and to reduce the manufacturing cost of the blades. It aims at providing the attachment method of a fastener, a cap, and a lightning-resistant fastener.

Lightning protection fastener of the present invention made in the above object includes a first member constituting the aircraft fuselage, through a second member disposed in the interior side of the fuselage, the second member side The protruding fastener body , the collar that fastens the second member to the first member by being attached to the fastener body, and the insulation provided on the second member side so as to cover the fastener body and the collar And a cap made of a material, and the cap is filled with an insulating sealant .
Such lightning-resistant fasteners can be applied not only to wings but also to other parts constituting the aircraft body.

The second member can be formed of a metal material.
In addition, a washer sandwiched between the second member and the collar can be further provided.
The fastener body and collar can be formed of a metallic material.

You may form the step part or collar part which protrudes toward the outer peripheral side in the outer peripheral surface of a color | collar.
  When the fastener body is formed of a metal material, it is preferable to form an insulating coating on the surface of the fastener body.

The cap may be formed with a bottomed hole in the inner peripheral surface thereof for accommodating the tip of the fastener body.
The washer can be formed of an insulating material.

The present invention further provides an aircraft equipped with the above described lightning-resistant fastener.
An example of the first member is a wing panel.
The first member can be made of CFRP, and the fastener body can be made of a metallic material. In this case, it is preferable that the coating film formed on the surface of the first member covers the rear end portion of the fastener body.
Examples of such a coating film include a paint containing copper.

The present invention also provides a method for attaching a lightning-resistant fastener. First, the fastener body is penetrated from the outside of the fuselage in a state where the first member constituting the aircraft fuselage and the second member attached to the first member inside the fuselage are overlapped. Next, a collar is attached to the fastener body from the inside of the fuselage. Then, a cap made of an insulating material is attached so as to cover the fastener body and the collar. This cap is characterized in that it is attached in a state where an uncured insulating sealant is filled therein.

The cap is preferably attached so that one end of the cap is in contact with the surface of the second member.
Further, the collar can be attached to the fastener body after the washer is attached from the inside of the fuselage. The washer is formed of an insulating material, for example.

As the cap used in the above method, a cap having a bottomed hole for accommodating the front end of the fastener main body can be used on the inner peripheral surface thereof.

According to the present invention, the first member and the second member are fastened with stable quality regardless of the operator while improving the workability and suppressing the manufacturing cost while ensuring the insulation. A cap can be attached to the tip of the fastener member.
In addition, since an insulating sealant is disposed between the cap and the fastener body , it is possible to ensure the sealing performance of the fastener body against fuel. Furthermore, since the sealant agent has an extremely tough arc prevention effect, the arc prevention effect is maintained even when the cap is broken, and a double arc prevention function can be provided by the cap and the sealant agent.

It is sectional drawing which shows the lightning-resistant fastener in this Embodiment. It is a perspective view of a cap. It is sectional drawing of a cap. It is a figure which shows the example which gave the slit process to the outer peripheral surface of the cap. It is a figure which shows the example which provided the processus | protrusion in the head part of the cap. It is a figure which shows the example which provided the knob | pick part in the head of the cap. It is sectional drawing which shows the other example of a cap. It is sectional drawing which shows the other example of the lightning-resistant fastener in this Embodiment. It is sectional drawing which shows the example of the conventional lightning-resistant fastener.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a cross-sectional view of a part of a wing constituting a fuselage of an aircraft to which a lightning-fastening fastener, a cap, and a lightning-fastening attachment method according to this embodiment are applied.
As shown in FIG. 1, the wing 20 has a wing panel (first fiber blade made of a metal material such as CFRP (Carbon Fiber Reinforced Plastics), which is a composite material of carbon fiber and resin, or an aluminum alloy. ) 21). A reinforcing structural material, a fuel tank, and various devices provided inside the wing 20 are connected to a wing panel 21 via a member (second member) 22 such as a stay formed of a metal material such as an aluminum alloy. It is fixed to. A member 22 such as a stay is attached to the wing panel 21 by a fastener member 24.

The fastener member 24 includes a pin-shaped fastener main body 25, a collar 26 attached to the fastener main body 25 on the inner side of the wing 20, and a washer 28.
The fastener body 25 and the collar 26 are generally formed of a metal material in terms of strength. The fastener main body 25 having a pin shape has a thread groove (engagement portion) 25a formed at the front end portion, and the rear end portion is a tapered diameter-expanding portion 25b having a diameter increased from the front end portion side. The fastener body 25 is inserted from the outside of the wing 20 into the holes 21a and 22a formed through the wing panel 21 and the member 22, and the enlarged diameter portion 25b at the rear end is abutted against the tapered surface of the hole 21a. In the state, the tip is projected inward of the wing 20.
The collar 26 has a cylindrical shape, and a thread groove 26 a that meshes with the thread groove 25 a of the fastener body 25 is formed on the inner peripheral surface thereof. The collar 26 is screwed into a thread groove 25 a of the fastener body 25 protruding inward of the wing 20. As a result, the wing panel 21 and the member 22 are sandwiched between the enlarged diameter portion 25 b of the fastener body 25 and the collar 26, and the member 22 is fixed to the wing panel 21.
In this state, the front end portion 25c of the fastener body 25 protrudes from the collar 26 toward the inner peripheral side of the blade 20, and further, a fixed length of the screw groove 25a is exposed from the collar 26 to the inner peripheral side of the blade 20. Yes.

Since the rear end portion of the fastener body 25 is exposed as it is on the surface of the wing 20, when the wing 20 is made of a composite material, the entire surface of the wing 20 is coated with a paint containing Cu (copper). The rear end portion of the fastener body 25 is covered with the film 27, thereby preventing current from concentrating on the fastener member 24 during a lightning strike.
Moreover, in order to prevent the lightning strike of the fastener main body 25, it is preferable to coat the surface of the fastener main body 25 with an insulating material such as a resin.

  The washer 28 is a ring having a predetermined thickness, and is formed of an insulating material such as polyimide. By forming the washer 28 with an insulating material, arc discharge is prevented from occurring at the interface between the member 22 and the washer 28.

Now, on the inner space side of the blade 20, a cap 30 is attached to the fastener member 24, and the cap 30 is filled with an insulating sealant agent 34.
As shown in FIGS. 2 and 3, the cap 30 is circular in cross section, and has a shape in which only the one end portion 30 a side is opened and the inner diameter and outer diameter gradually decrease toward the other end portion 30 b side. This cap is preferably formed of an insulating resin such as PPS (polyphenylene sulfide resin), polyimide, PEEK (polyether-ether-ketone resin), or nylon resin.

  A bottomed hole (engaged portion) 32 having a circular cross section is formed on the inner peripheral surface (hereinafter referred to as a bottom surface 31) of the cap 30 on the other end 30b side. A thread groove 32a that meshes with the thread groove 25a of the fastener body 25 is formed on the inner peripheral surface. The cap 30 is configured such that the distal end portion 25 c of the fastener body 25 is inserted into the hole 32 in a state where the end surface of the one end portion 30 a is pressed against the member 22. At this time, the screw groove 32 a of the cap 30 is engaged with the screw groove 25 a of the fastener body 25, so that the cap 30 can be easily and reliably positioned and fixed to the fastener member 24.

  Such a cap 30 has an inner diameter of the inner peripheral surface 36 such that a predetermined gap is formed between the washer 28, the fastener body 25 and the collar 26 when the cap 30 is attached to the fastener member 24. Is set. In particular, the cap 30 is formed at the one end 30a on the opening side of the cap 30 so that a gap of a predetermined dimension t or more can be secured between the inner peripheral surface of the cap 30 and the washer 28 and the fastener body 25. Yes.

The inner peripheral surface 36 of the cap 30 has a straight portion 36a having a constant inner diameter on the one end 30a side, and further, a tapered portion 36b whose inner diameter gradually decreases from the straight portion 36a toward the hole 32. Is formed.
The corner portion 36c where the straight portion 36a and the taper portion 36b are adjacent to each other, and the corner portion 36d where the taper portion 36b and the hole 32 are adjacent to each other have an R shape having a predetermined radius of curvature.
Thus, the inner peripheral surface 36 of the cap 30 is a surface that smoothly continues from the straight portion 36a to the corner portion 36c, the tapered portion 36b, and the corner portion 36d. As a result, when the sealant agent 34 is filled in the cap 30, air is entrained in the sealant agent 34, or voids are formed in the sealant agent 34 on the inner peripheral surface 36 (particularly, the corner portions 36 c and 36 d). It comes to prevent.

  In a state where the cap 30 is attached to the fastener member 24, the cap 30 is filled with a sealant agent 34 having an insulating property. The sealant agent 34 is interposed between the inner peripheral surface of the cap 30 and the fastener body 25 and the collar 26, so that the insulation between the cap 30 and the fastener member 24 is further enhanced. And in the one end part 30a which is the opening side of the cap 30, the sealant agent 34 between the inner peripheral surface 36 of the cap 30, the washer 28, and the fastener main body 25 has thickness more than the predetermined dimension t. Therefore, the insulation performance at the interface between the inner peripheral surface 36 of the cap 30 and the washer 28 and the fastener body 25 is ensured.

When the cap 30 is attached to the fastener member 24 that fastens the wing panel 21 and the member 22, the cap 30 is filled with an uncured sealant 34. Then, the cap 30 is pressed against the fastener body 25 of each fastener member 24 protruding inward in the internal space of the blade 20.
At this time, the sealant 34 filled in the cap 30 overflows from the opening of the one end 30 a of the cap 30. It is preferable that the sealant 34 overflows from the entire circumference of the cap 30 so that the sealant 34 is evenly distributed throughout the entire area of the cap 30. Therefore, the surface 37 of the one end portion 30a of the cap 30 is preferably a smooth surface, and the inner peripheral edge portion 38 of the one end portion 30a is preferably formed so as not to cause burrs or burrs.
When the cap 30 is pressed against the fastener body 25, the hole 32 is formed inside the cap 30, so that the fastener member 24 can be reliably and easily positioned at the center of the cap 30. Accordingly, the cap 30 and the fastener member 24 are not displaced, and the gap between the cap 30 and the fastener member 24 is not narrowed depending on the location, and the fastener member 24 can be prevented from directly contacting the cap 30. .

  In order to easily position the cap 30 on the fastener member 24, it is also effective to make the peripheral portion of the hole 32 have a tapered surface whose inner diameter gradually decreases toward the inner side of the hole 32.

After the hole 32 of the cap 30 is pressed against the fastener body 25, the cap 30 is rotated and screwed into the fastener body 25.
At this time, if the sealant 34 is filled in the hole 32, the distal end portion 25 c of the fastener body 25 is inserted into the hole 32. Further, when the fastener main body 25 enters the hole 32 as the cap 30 is screwed in, there is no place for the sealant agent 34 in the hole 32, and the pressure of the sealant agent 34 is increased, so that the tip of the fastener main body 25 is opened. It may not be possible to insert up to 32 predetermined depths.
Therefore, it is preferable to form a groove 33 extending along the central axis direction of the hole 32 at least at one place on the inner peripheral surface of the hole 32 of the cap 30. In the example of FIGS. 2 and 3, two grooves 33 are formed in the hole 32. Of course, three or more grooves 33 can be formed.
Thus, by forming the groove 33 in the hole 32, when the tip end portion of the fastener body 25 is inserted into the hole 32, the excess sealant agent in the hole 32 passes through the groove 33. It is pushed out from the hole 32. Accordingly, it is possible to prevent a gap from remaining in the sealant agent 34 in the hole 32 and to easily insert the fastener body 25 into the hole 32, that is, to attach the cap 30 to the fastener member 24.

Then, when the cap 30 is screwed in until the end face of the one end 30a of the cap 30 is pressed against the member 22, the screwing of the cap 30 is completed. Then, in this state, the screw groove 25a formed in the fastener body 25 and the screw groove 32a of the hole 32 of the cap 30 are engaged with each other, so that the cap 30 is securely fixed to the fastener member 24.
Further, when the filled sealant 34 is cured, this sealant 34 also exerts an effect of fixing the cap 30 to the fastener member 24.
The fastener member 24 to which the cap 30 is thus attached is a lightning-resistant fastener.

Here, the cap 30 may fall off due to an impact or the like when something hits the outer peripheral surface of the cap 30. Even in such a case, it is preferable to maintain the state where the sealant 34 covers the head of the fastener body 25 without dropping the cured sealant 34 together with the cap 30.
For this purpose, the material of the sealant 34 is preferably selected so that the adhesive force between the cap 30 and the sealant 34 is weaker than the adhesive force between the sealant 34 and the fastener member 24. Thus, if the adhesive force between the cap 30 and the sealant agent 34 is weaker than the adhesive force between the sealant agent 34 and the fastener member 24, the cap 30 is peeled off from the sealant agent 34 even when an impact is applied to the cap 30. As a result, only the cap 30 is dropped, and the fastener member 24 is kept covered with the sealant 34, so that the lightning resistance can be maintained.

  In order to prevent the sealant agent 34 from being peeled off from the fastener member 24, for example, a step portion 26c projecting toward the outer peripheral side, a collar portion 26d, or the like may be formed on the outer peripheral surface of the collar 26.

By the way, the cap 30 may be screwed by a worker using a tool or may be screwed by hand.
For example, when the operator screws the cap 30 with a tool, as shown in FIGS. 2 and 3, the head 30c of the other end 30b of the cap 30 has a hexagonal shape, a hexagonal hole shape, or the like corresponding to the tool shape. be able to.
Further, when the cap 30 is screwed by an operator by hand, as shown in FIG. 4, slit processing, knurling processing, diamond cutting processing, or the like can be applied to the outer peripheral surface 30 d of the cap 30 to prevent slippage. Of course, in the example of FIG. 4, the entire outer peripheral surface 30d of the cap 30 is slitted, but may be applied to only a part thereof. Further, as shown in FIG. 5, a plurality of (two or more) protrusions 35 may be formed on the other end 30 b of the cap 30 at intervals in the circumferential direction. There is no question about the number or shape of the protrusions 35.

  In addition, as shown in FIG. 6, an appropriately shaped knob 30g can be formed on the head 30e of the cap 30 via a rod 30f having a predetermined outer diameter. In such a configuration, the operator attaches the cap 30 to the fastener member 24 by turning the knob 30g. At this time, by setting the part 30h of the rod part 30f to be thin, the strength is set so that the part 30h of the rod part 30f can be threaded when the predetermined tightening torque of the cap 30 is reached. Thus, the operator can securely attach the cap 30 with the specified torque.

As described above, by forming the hole 32 in the cap 30 and forming the screw groove 32a in the hole 32, the cap 30 can be securely and easily positioned and attached to the fastener member 24. Even afterward, the cap 30 can be reliably prevented from falling off.
Further, if the cap 30 is screwed into the fastener member 24, it is not necessary to wait for the sealant 34 to be cured, and the cap 30 can be quickly attached.
Thereby, after ensuring insulation reliably, while improving workability | operativity and suppressing manufacturing cost, it can attach with stable quality irrespective of an operator.
In addition, the cap 30 is made of resin, so that mass production becomes easy, the manufacturing cost is reduced, the thickness is easily managed by mass production, and the cap 30 can be reduced in weight.

  The cap 30 as described above can be formed by cutting, but is preferably formed by injection molding in consideration of mass productivity. In the case of injection molding, since it is difficult to form the screw groove 32a of the hole 32 (the cap 30 needs to be removed after the formation), the screw groove 32a is formed by screwing the helisert into the hole 32. It may be attached.

  In the above embodiment, the groove 33 is formed in the hole 32 to push out the surplus of the sealant 34 filled in the hole 32. However, the present invention is not limited to this. For example, FIG. As shown, the through hole 40 can be formed in the head 30 c of the cap 30, and the surplus sealant 34 can be pushed out of the cap 30 from the through hole 40.

In the above embodiment, the cap 30 is screwed into the screw groove 25a formed at the tip of the fastener main body 25 of the fastener member 24. However, the cap member 24 protrudes inward from the wing 20 in the fastener member 24. Other different configurations are possible as long as 30 is screwed.
For example, as shown in FIG. 8, a screw groove 26 b is formed on the outer peripheral surface of the collar 26 attached to the fastener body 25 on the inner side of the wing 20, and the screw groove 26 b is formed on the inner peripheral surface of the cap 30. Alternatively, the thread groove 32b may be screwed.
Furthermore, the cap 30 is not limited to the configuration in which the cap 30 is screwed into the screw groove 25a formed in the front end portion of the fastener main body 25 of the fastener member 24, and the cap 30 may be configured to fit the front end portion of the fastener main body 25. . In that case, for example, a circumferentially continuous groove or protrusion is formed on the outer peripheral surface of the front end portion of the fastener body 25, and a protrusion or protrusion that engages with the groove of the fastener body 25 is formed in the hole 32 of the cap 30. Alternatively, it is possible to form a groove that engages with the convex shape of the fastener body 25 and to fit the cap 30 to the fastener body 25.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

  20 ... Wings, 21 ... Wing panel (first member), 21a ... Hole, 22 ... Member (second member), 24 ... Fastener member, 25 ... Fastener body, 25a ... Screw groove (engaging portion), 25b ... diameter-expanded part, 25c ... tip part, 26 ... collar, 26a ... thread groove, 30 ... cap, 30a ... one end part, 30b ... other end part, 30c ... head, 30d ... outer peripheral surface, 30e ... head, 30f ... Rod part, 30g ... Knob part, 31 ... Bottom, 32 ... Hole (engaged part), 32a ... Screw groove, 33 ... Groove, 34 ... Sealant agent, 35 ... Projection, 40 ... Through hole

Claims (17)

Fastener body that penetrates the first member constituting the aircraft body and the second member disposed on the inner side of the aircraft, and protrudes toward the second member side;
A collar that fastens the second member to the first member by being attached to the fastener body;
A cap made of an insulating material provided on the second member side so as to cover the fastener body and the collar,
A lightning-resistant fastener, wherein the cap is filled with an insulating sealant.   The lightning-resistant fastener according to claim 1, wherein the second member is made of a metal material.   The lightning-resistant fastener according to claim 1, further comprising a washer sandwiched between the second member and the collar.   The lightning-resistant fastener according to any one of claims 1 to 3, wherein the fastener main body and the collar are formed of a metal material.   5. The lightning-resistant fastener according to claim 1, wherein a stepped portion or a flange portion that protrudes toward the outer peripheral side is formed on the outer peripheral surface of the collar.   The lightning-resistant fastener according to any one of claims 1 to 5, wherein the fastener body is made of a metal material, and an insulating coating is formed on a surface of the fastener body.   The lightning-resistant fastener according to any one of claims 1 to 6, wherein the cap has a bottomed hole that accommodates a front end portion of the fastener body on an inner peripheral surface thereof.   The lightning-resistant fastener according to claim 3, wherein the washer is formed of an insulating material.   An aircraft comprising the lightning-resistant fastener according to any one of claims 1 to 8.   The aircraft of claim 9, wherein the first member is a wing panel. The first member is made of CFRP (Carbon Fiber Reinforced Plastics), and the fastener body is made of a metal material;
The aircraft according to claim 9 or 10, wherein a coating film formed on a surface of the first member covers a rear end portion of the fastener body.   The aircraft according to claim 11, wherein the coating film is made of a paint containing copper. A step of penetrating a fastener main body from the outside of the fuselage in a state where a first member constituting the aircraft fuselage and a second member attached to the first member on the inside of the fuselage are overlapped; ,
Attaching a collar to the fastener body from the inside of the fuselage;
Attaching a cap made of an insulating material so as to cover the fastener body and the collar;
With
A method of attaching a lightning-resistant fastener, wherein the cap is attached in a state where an uncured insulating sealant is filled therein.   The method for attaching a lightning-resistant fastener according to claim 13, wherein the cap is attached so that one end of the cap is in contact with the surface of the second member.   The method for attaching a lightning-resistant fastener according to claim 13 or 14, wherein the collar is attached to the fastener main body after a washer is attached from an inner side of the fuselage.   The method for attaching a lightning-resistant fastener according to claim 15, wherein the washer is formed of an insulating material.   17. The lightning-resistant fastener according to claim 13, wherein the cap has a bottomed hole that accommodates a front end portion of the fastener body on an inner peripheral surface thereof. installation method.

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