JP7470758B2 - Rotary fastener loosening detection device, corrosion prevention method for rotary fastener equipped with rotary fastener loosening detection device, and rotary fastener loosening detection system - Google Patents

Description

This disclosure relates to a rotary fastener loosening detection device that detects loosening of a bolt or nut, a corrosion prevention method for a rotary fastener equipped with a rotary fastener loosening detection device, and a rotary fastener loosening detection system.

Traditionally, anti-corrosion systems that are effective by covering the bolts with anti-corrosion materials have been applied to the protection of anchor bolts. Most of these systems have been adopted only for the purpose of maintaining the anti-corrosion effect. However, in recent years, as highways and bridges built during the high-growth period of the 1970s have deteriorated, corrosion of anchor bolts and their plates for lighting and other purposes has become a problem. The effects of corrosion and other factors have also been discussed for high-strength bolts and other parts that are unique to steel structures. However, infrastructure facilities related to transportation, such as highways and bridges, are not only prone to corrosion, but also to loosening of bolts and nuts due to vehicle vibrations, etc., which causes problems. Therefore, in order to maintain structures, it is necessary to deal with both corrosion and loosening of bolts and nuts. A common method for detecting loosening is to check by tapping. However, even if corrosion is possible with the anti-corrosion method of covering bolts and nuts with anti-corrosion materials, it is impossible to detect loosening because tapping checks cannot be performed.

On the other hand, there is a known method for detecting loose bolts and nuts using RFID (radio frequency identifier) technology (see, for example, Patent Document 1 and Patent Document 2).

JP 2020-101977 A JP 2021-105589 A

However, the methods described in Patent Documents 1 and 2 are not very practical because even a slight loosening of a bolt or nut is detected as looseness. If even a slight loosening is detected, a state in which repair or the like is not actually required will be detected.
Furthermore, the method of Patent Document 1 has low practicality because the antenna is located adjacent to the head of the metal bolt, which deteriorates communication conditions via the antenna and shortens the communication distance. In addition, the method is attached using an adhesive material that may peel off.
Furthermore, the methods disclosed in Patent Documents 1 and 2 do not take into consideration corrosion prevention, making it difficult to achieve both loosening detection and corrosion prevention.
Therefore, conventional methods for detecting looseness have little practical use, and tapping checks remain the most effective inspection method.

An object of the present disclosure is to provide a rotary fastener loosening detection device that can arbitrarily set the rotation angle for detecting loosening of a rotary fastener in multiple stages, a corrosion prevention method for a rotary fastener equipped with a rotary fastener loosening detection device, and a rotary fastener loosening detection system.
Furthermore, a further object of the present disclosure is to provide a rotary fastener loosening detection device to which a corrosion-resistant structure can be easily applied, a corrosion protection method for a rotary fastener in which a rotary fastener loosening detection device is installed, and a rotary fastener loosening detection system.

The present disclosure solves the above problems by the following solutions. Note that, for ease of understanding, the following explanations are given with reference symbols corresponding to the embodiments of the present disclosure, but the present disclosure is not limited to these.

The first disclosure is a device (1) for detecting loosening of a rotary fastener, comprising: a rotary member (30) that engages with the external shape of the head of a bolt or the external shape of a nut (103) and is provided so as to be rotatable in accordance with the rotation of the bolt or the nut (103); a fixed member (50) that is arranged along the rotary member (30) and is fixed to a base (110) so as not to rotate; and an RFID tag (60) having an antenna (61a, 61b, 62a, 62b) and a state detection wire (61c, 62c), in which the RFID tag (60) is provided on one of the rotary member (30) and the fixed member (50), and a cutting section (40) is provided on the other, and the cutting section (40) cuts the state detection wire (61c, 62c) by the rotation of the rotary member (30).

The second disclosure is a rotary fastener loosening detection device (1) described in the first disclosure, in which a plurality of state detection wires (61c, 62c) are provided, and the plurality of state detection wires (61c, 62c) are each cut by the cutting portion (40) at a different rotation angle of the rotating member (30).

The third disclosure is a rotary fastener loosening detection device (1) described in the first or second disclosure, in which the antenna (61a, 61b, 62a, 62b) is spaced apart from the bolt and the nut (103).

The fourth disclosure is a device (1) for detecting loosening of a rotary fastener as described in any one of the first to third disclosures, in which the rotating member (30) engages with the external shape of the nut (103) and rotates in accordance with the rotation of the nut (103), the bolt (101) into which the nut (103) is screwed is provided with an excess portion protruding from the nut (103), and the fixing member (50) is fixed to a base (110) by utilizing the excess portion.

The fifth disclosure is a rotary fastener loosening detection device (1) described in any one of the first to fourth disclosures, in which the RFID tag (60) is a passive type.

The sixth disclosure is a rotary fastener loosening detection device (1) described in any one of the first to fifth disclosures, in which a sacrificial protective material (210) is arranged in the inner area of the rotary member (30) and the fixed member (50).

The seventh disclosure is a rotary fastener loosening detection device (1) described in any one of the first to sixth disclosures, in which the inner regions of the rotary member (30) and the fixed member (50) are filled with a petrolatum-based anticorrosive agent (220).

The eighth disclosure is a rotary fastener loosening detection device (1) according to any one of the first to seventh disclosures, which has a cover (70) that covers the rotary member (30) and the fixed member (50), and the outside of the cover (70) is covered with a waterproof exterior material (230).

The ninth disclosure is a corrosion prevention method for a rotary fastener in which a rotary fastener loosening detection device (1) described in any one of the first to sixth disclosures is installed, in which a petrolatum-based corrosion prevention material (220) is filled in the inner area of the rotating member (30) and the fixed member (50).

The tenth disclosure is a corrosion prevention method for a rotary fastener equipped with a rotary fastener loosening detection device (1) described in any one of the first to seventh disclosures, in which a cover (70) is disposed to cover the rotating member (30) and the fixed member (50), and the outside of the cover (70) is covered with a waterproof exterior material (230).

The eleventh disclosure is a system for detecting loosening of a rotary fastener, comprising the rotary fastener loosening detection device (1) described in the second disclosure and an RFID reader (500) that communicates with the RFID tag (60), and that recognizes the degree of the loosening angle of the bolt or nut (103) in stages from the communication results of the RFID reader (500).

According to the present disclosure, it is possible to provide a rotary fastener loosening detection device that can arbitrarily set the rotation angle for detecting loosening of a rotary fastener in multiple stages, a corrosion prevention method for a rotary fastener equipped with a rotary fastener loosening detection device, and a rotary fastener loosening detection system.
In addition, the present disclosure can provide a rotary fastener loosening detection device to which a corrosion-resistant structure can be easily applied, a corrosion prevention method for a rotary fastener in which a rotary fastener loosening detection device is installed, and a rotary fastener loosening detection system.

1 is a perspective view showing the appearance of an embodiment of a device 1 for detecting loosening of a rotary fastener according to the present disclosure; 2 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener taken along the line AA in FIG. 1. 1 is a perspective view showing a bolt 101, a nut 102, a nut 103, and a washer 104 before the device 1 for detecting loosening of a rotary fastener is attached. FIG. FIG. 4 is a perspective view showing a state in which an anti-vibration ring 10 and an anti-corrosion ring 210 are attached to the state shown in FIG. 3 . 5 is a cross-sectional view of the rotary fastener loosening detection device 1 in the middle of assembly taken along the position of the arrow B-B in FIG. 4. FIG. 5 is a perspective view showing a state in which a support base 20 is attached to the state shown in FIG. 4 7 is a cross-sectional view of the rotary fastener loosening detection device 1 in the middle of assembly taken along the position of the arrow CC in FIG. 6. FIG. 7 is a perspective view showing a state in which a rotating member 30 is attached to the state shown in FIG. 6 . 9 is a cross-sectional view of the rotary fastener loosening detection device 1 in the middle of assembly taken along the position of the arrow DD in FIG. 8. FIG. 9 is a perspective view showing a state in which a fixing member 50 and an RFID tag 60 are attached to the state shown in FIG. 8 . FIG. 11 is a perspective view showing a state in which an RFID tag 60 is removed from FIG. 10 . 11 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener during assembly taken along the position of the arrow E-E in FIG. FIG. 2 is an exploded view of the RFID tag 60. 11 is a perspective view showing a state in which a cover 70 is attached to the state shown in FIG. 10 . 15 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener during assembly taken along the position of the arrow F-F in FIG. 14. 15 is a perspective view showing a state in which a fastening member 80 is attached to the state shown in FIG. 14. FIG. 17 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener during assembly taken along the position of the arrow G-G in FIG. 16. FIG. 1 is a diagram showing an overview of a system for detecting loosening of a rotary fastener.

The best mode for implementing this disclosure will be described below with reference to the drawings etc.

(Embodiment)
FIG. 1 is a perspective view showing the appearance of an embodiment of a device 1 for detecting loosening of a rotary fastener according to the present disclosure.
FIG. 2 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener taken along the line indicated by the arrows AA in FIG.
Note that the figures shown below, including FIG. 1, are schematic views, and the size and shape of each part are exaggerated or omitted as appropriate for ease of understanding.
In the following description, specific numerical values, shapes, materials, etc. are given, but these can be changed as appropriate.
It should be noted that the specific numerical values specified in this specification and claims should be treated as including a general error range. In other words, a difference of about ±10% means that there is no substantial difference, and values set within a range slightly exceeding the numerical range of this case should be interpreted as being substantially within the technical scope of this disclosure.
In the following explanation, directional terms such as "up" and "down" will be used to correspond to the directions corresponding to the upper and lower sides in Figure 2, etc., but this is used for convenience of explanation and does not limit the direction relative to the vertical direction when the rotary fastener loosening detection device 1 is in use.

The rotary fastener loosening detection device 1 of this embodiment is a device that detects loosening of a nut 103 that screws onto a bolt 101 to fix a base member 110, and is covered with an exterior material 230. The rotary fastener loosening detection device 1 includes an anti-vibration ring 10, a support base 20, a rotating member 30, a cutting portion 40, a fixing member 50, an RFID tag 60, a cover 70, and a tightening member 80. The rotary fastener loosening detection device 1 also includes an anti-corrosion ring 210, an anti-corrosion material 220, and an exterior material 230 as a configuration for corrosion prevention.
Hereinafter, each of the above components will be described along with the assembly process of the device 1 for detecting loosening of a rotary fastener.

FIG. 3 is a perspective view showing the bolt 101, the nut 102, the nut 103, and the washer 104 before the device 1 for detecting loosening of a rotary fastener is attached.
The bolt 101 is an anchor bolt embedded in a base 120 formed of concrete or the like. In the present embodiment, the bolt 101 is an anchor bolt, but it may be a normal bolt with a head. The base 120 is not limited to concrete, and may be a steel material or the like.
Nuts 102 and 103 are hexagonal nuts that are fastened by screwing onto bolt 101 with washer 104 sandwiched between them and base member 110, fixing base member 110 to board 120. Nut 102 is disposed closer to base member 110 than nut 103. In this manner, this embodiment illustrates a double nut configuration that uses two nuts, nut 102 and nut 103, providing an enhanced anti-loosening effect.
The base member 110 may be made of any material, but is envisaged to be made of steel, for example.
With washer 104, nut 102, and nut 103 attached, the amount of excess length that the tip of bolt 101 protrudes from nut 103 is preferably such that three or more threads of bolt 101 remain.

(Installation process of anti-vibration ring 10 and anti-corrosion ring 210)
First, the vibration-isolating ring 10 and the anticorrosive ring 210 are attached to the state shown in FIG.
FIG. 4 is a perspective view showing a state in which the anti-vibration ring 10 and the anti-corrosion ring 210 are attached to the state shown in FIG.
FIG. 5 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener during assembly taken along the position of the arrows BB in FIG.
The anti-vibration ring 10 is a ring made of rubber or the like, having approximately the same outer diameter as the washer 104, and is placed on the washer 104. The anti-vibration ring 10 may simply be placed on the washer 104, or may be glued to the washer 104. The anti-vibration ring 10 is provided to prevent vibration of the rotating member 30, which will be described later.

The anticorrosion ring 210 is made of a sacrificial anticorrosive material such as a magnesium alloy. The anticorrosion ring 210 is attached to the base member 110 around the periphery of the washer 104 using a conductive adhesive. The anticorrosion ring 210 is provided to prevent corrosion caused by an electrolyte such as water that seeps in from the surroundings.
Furthermore, the entire circumference of area PA1 (the exposed portion of anticorrosive ring 210) and area PA2 (the gap inside vibration-damping ring 10 and the periphery of nut 102) shown by the dotted line on the left side of Figure 5 is coated or filled with a petrolatum-based anticorrosive material 220 (see Figure 2).
The petrolatum-based corrosion inhibitor is an effective corrosion inhibitor that, by cutting off the supply of oxygen, stops the progression of corrosion of the bolts 101, nuts 102 and 103, washers 104, and base member 110. In addition, by installing a corrosion inhibitor ring 210 in the vicinity of the bolts, it is possible to provide even more powerful corrosion protection.
By disposing or filling the anticorrosive ring 210 and the petrolatum-based anticorrosive material in the inner regions of the rotating member 30 and the fixed member 50 described below, a high anticorrosive effect can be achieved.

(Installation process of the support base 20)
Next, the support base 20 is attached.
FIG. 6 is a perspective view showing a state in which the support base 20 is attached to the state shown in FIG.
FIG. 7 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener during assembly taken along the position of the arrow CC in FIG.
The support base 20 is a member that supports and fixes the fixing member 50 described later, and is fixed to the base member 110 using an adhesive. It is desirable for the support base 20 to be a resin molded product in terms of manufacturing, cost, corrosion resistance, etc.
Before proceeding to the next step, the previously applied petrolatum-based anticorrosive agent may be additionally coated or filled.

(Step of attaching the rotating member 30)
Next, the rotating member 30 is attached.
FIG. 8 is a perspective view showing a state in which the rotating member 30 is attached to the state shown in FIG.
FIG. 9 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener in the process of being assembled, taken along the position of the arrows DD in FIG.
The rotating member 30 has an outer circumferential surface formed into a substantially cylindrical surface, and is provided with a cutting portion attachment shape 31 that is recessed by one step on the outer circumferential surface, and a cutting portion 40 is attached using a screw (not shown).
The inner surface of the rotating member 30 is provided with a lower nut escape portion 32, an upper nut fitting portion 33, and a gap portion 34.
It is desirable that the rotating member 30 be a resin molded product in terms of manufacturing, cost, corrosion resistance, etc. In addition, it is desirable that the rotating member 30 be a resin molded product so as not to impede communication of the RFID tag 60.

The lower nut recess 32 is provided penetrating the lower end side (base member 110 side) of the rotating member 30. The lower nut recess 32 is shaped so that when the rotating member 30 rotates, the nut 102 (lower nut) does not interfere with the rotation of the rotating member 30 and the rotation of the rotating member 30 is not restricted, and the lower nut recess 32 has a cylindrical inner surface shape that is sufficiently larger than the outer diameter shape of the nut 102.

The upper nut fitting portion 33 is provided above the lower nut recess 32 in communication with the lower nut recess 32, and is formed into the inner shape of a hexagonal tube that fits into the hexagonal outer shape of the nut 103. Since the upper nut fitting portion 33 fits into the nut 103 with almost no gap, the rotating member 30 can rotate in conjunction with the rotation of the nut 103. Note that in Figure 9 and other figures, the gap between the upper nut fitting portion 33 and the nut 103 is greatly exaggerated to clearly show it, but in reality this gap is very small.

In a double nut like this embodiment, loosening can be controlled on the nut 102 side (lower nut side) or on the nut 103 side (upper nut side). In this embodiment, the configuration in which loosening is controlled on the nut 103 side (upper nut side) is illustrated, and therefore the configuration of the lower nut escape portion 32 and the upper nut fitting portion 33 described above is used. However, the configuration in which the nut 102 side (lower nut side) and the rotating member 30 engage can also be used to detect loosening on the nut 102 side (lower nut side). The present invention can also be applied to a single nut with a single nut configuration, or to the head of a bolt.

The gap 34 is a gap that is connected to the upper nut fitting portion 33 on the upper side and penetrates upward, and has a cylindrical inner surface shape except for the position corresponding to the cutting portion mounting shape 31. The bottom surface position of the gap 34 is approximately the same as the top surface position of the nut 103.

The cutting portion 40 has a base portion 41 and a cutting blade 42 .
The base portion 41 has two screw holes 41a, and is fixed to the cutting portion mounting shape 31 of the rotating member 30 using a screw (not shown) and these screw holes 41a.
The cutting blade 42 is a blade that cuts an RFID tag 60 (described later), and is fixed to the base portion 41 in a form that protrudes outward from the base portion 41 .
Since the cutting portion 40 is fixed to the rotating member 30 , the cutting blade 42 rotates integrally with the rotating member 30 .

(Step of attaching the fixing member 50 and the RFID tag 60)
Next, the fixing member 50 and the RFID tag 60 are attached.
FIG. 10 is a perspective view showing a state in which the fixing member 50 and the RFID tag 60 are attached to the state shown in FIG.
FIG. 11 is a perspective view showing a state in which the RFID tag 60 is removed from FIG.
FIG. 12 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener in the process of being assembled, taken along the position of the arrow E--E in FIG.

The fixed member 50 is formed in a generally cylindrical shape, has a shape that generally covers the outside of the rotating member 30, and is disposed along the rotating member 30. The fixed member 50 has a side opening 51, a slit 52, a flange portion 53, an upper surface portion 54, and a through hole 55.
The side opening 51 has a shape that opens downward from the position where the cutting blade 42 is provided. The side opening 51 has a shape that prevents the cutting blade 42 from interfering with the fixing member 50 by passing through the side opening 51 when the fixing member 50 is attached.
The slit 52 is provided on the side surface along the circumferential direction from the side opening 51, and when the rotating member 30 rotates in conjunction with the rotation of the nut 103, the cutting blade 42 passes through this slit 52 while cutting the RFID tag 60.
The flange portion 53 is provided at the lower end side of the fixing member 50 so as to protrude in a flange-like shape toward the outer periphery, and is adhesively fixed to the support base 20. In this embodiment, the support base 20 is provided and the fixing member 50 is fixed to the support base 20, thereby fixing the fixing member 50 so as not to rotate with respect to the base member 110. However, the fixing member 50 may be fixed directly to the base member 110 so as not to rotate with respect to the base member 110 without using the support base 20.
The upper surface portion 54 forms a ceiling surface at the upper end side of the fixing member 50, and a through hole 55 is opened in the center thereof.
The fixing member 50 is preferably a resin molded product in terms of manufacturing, cost, corrosion resistance, etc. Also, the fixing member 50 is preferably a resin molded product so as not to impede communication of the RFID tag 60.

The RFID tag 60 is attached to the outer circumferential surface of the fixing member 50 .
FIG. 13 is a development view of the RFID tag 60. As shown in FIG.
The RFID tag 60 may be configured, for example, by forming a circuit with a conductor on a sheet-like substrate made of polyimide resin. The RFID tag 60 of this embodiment has two RFID circuits, a first RFID circuit 61 and a second RFID circuit 62, integrated on one substrate.

The first RFID circuit 61 is a passive RFID circuit having antennas 61a and 61b, a state detection wiring 61c, and an IC chip 61d, and is configured as an independent RFID tag. The first RFID circuit 61 is capable of communicating with an RFID reader 500 (described later) from a distance of about 2 to 5 m using a UHF frequency band.
The antennas 61a and 61b are used to communicate with an RFID reader 500, which will be described later.
The state detection wire 61c is provided at a position where it is cut by the rotational movement of the cutting unit 40 (cutting blade 42). Whether the state detection wire 61c is cut or not is detected by the IC chip 61d.
The IC chip 61d is connected to the antennas 61a and 61b and the state detection wiring 61c, and has a tamper function. The tamper function is also called a tamper detection function, and has been used in the past to detect, for example, the opening of a label by detecting a broken wire.

The second RFID circuit 62 has a similar configuration to the first RFID circuit 61 .
That is, the second RFID circuit 62 is a passive type RFID circuit having antennas 62a and 62b, a state detection wiring 62c, and an IC chip 62d, and is configured as an independent RFID tag. The second RFID circuit 62 is capable of communicating with an RFID reader 500 (described later) from a distance of about 2 to 5 m using a UHF frequency band.
The antennas 62a and 62b are used to communicate with an RFID reader 500, which will be described later.
The state detection wire 62c is provided at a position where it is cut by the rotational movement of the cutting unit 40 (cutting blade 42). Whether or not the state detection wire 62c is cut is detected by an IC chip 62d.
The IC chip 62d is connected to the antennas 62a and 62b and the state detection wiring 62c, and has a tamper function.

Here, the state detection wiring 61c and the state detection wiring 62c are arranged side by side on the planned cutting line CL shown by the two-dot chain line in Figures 10 and 13. This planned cutting line CL indicates the position where the cutting unit 40 (cutting blade 42) is scheduled to cut the RFID tag 60 by rotating the rotating member 30. Note that the planned cutting line CL is an imaginary line drawn for convenience of explanation. The state detection wiring 61c is arranged closer to the cutting blade 42 than the state detection wiring 62c. Note that in Figure 10, the cutting blade 42 of the cutting unit 40 is drawn at a position away from the V-shaped cutout on the planned cutting line CL of the RFID tag 60 for ease of understanding. However, when the rotating fastener loosening detection device 1 is installed, the position is adjusted so that the cutting blade 42 is in contact with the bottom of the V-shaped cutout of the RFID tag 60, and then fixed. Therefore, as shown in FIG. 10, when the rotating member 30 rotates an angle θ1, the state detection wire 61c is first cut, and when the rotating member 30 further rotates an angle θ2, the state detection wire 62c is also cut. In this way, in this embodiment, the rotation of the rotating member 30, i.e., the loosening of the nut 103, can be detected in two stages.

In addition, the angle θ1 by which the cutting unit 40 shown in FIG. 10 rotates to the position where it cuts the state detection wire 61c, and the angle θ2 by which the cutting unit 40 rotates from the position where it cuts the state detection wire 61c to the position where it cuts the state detection wire 62c can be appropriately set according to the angle to be detected (loosening angle of the nut). For example, it is recommended to set the angle θ1 = angle θ2 = 15 degrees. In the conventional tapping check, since the loosening angle of the nut is detected as abnormal when it is 30 degrees or more, if the above angle is set, the state detection wire 61c is cut at 15 degrees, which is half the angle of 30 degrees that is determined to be abnormal in the conventional tapping check. Therefore, when the state detection wire 61c is cut, it becomes possible to prepare and plan for repairs in advance. In addition, when the nut 103 is further loosened and rotated 30 degrees from the initial position, the state detection wire 62c is cut, so that loosening detection similar to the conventional tapping check can be performed.
The above-mentioned setting of angle θ1 = angle θ2 = 15 degrees is just an example, and these angles θ1 and θ2 can be easily changed simply by changing the arrangement of the state detection wires 61c and 62c in the RFID tag 60. Therefore, loosening detection can be performed at any detection angle.

As shown in FIG. 12, a space is provided between the RFID tag 60 and the bolt 101, and between the RFID tag 60 and the nuts 102 and 103. Therefore, the antennas 61a, 61b, 62a, and 62b are spaced from the bolt 101 and the nuts 102 and 103. This prevents the bolt 101 and the nuts 102 and 103, which are metals, from adversely affecting the communication of the RFID tag 60, and allows for stable and reliable communication. Note that the distance that the RFID tag 60 is spaced from the metal (nuts, bolts, etc.) is preferably 10 mm or more, and more preferably 20 mm or more, in order to achieve stable and reliable communication.

(Cover 70 Attachment Process)
Next, the cover 70 is attached.
FIG. 14 is a perspective view showing a state where the cover 70 is attached to the state shown in FIG.
FIG. 15 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener in the process of being assembled, taken along the position of the arrows F--F in FIG.
The cover 70 is formed in a generally cylindrical shape and is shaped to generally cover the outside of the fixing member 50. The cover 70 has an upper surface portion 71 and a through hole 72, and is open downward.
The upper surface portion 71 forms a ceiling surface at the upper end side of the cover 70, and a through hole 72 is opened in the center thereof. The opening diameter of the through hole 72 is larger than the opening diameter of the through hole 55. The upper surface portion 71 is disposed in close contact with the upper surface portion 54 of the fixing member 50, and the lower end of the cover 70 is disposed with a small gap between it and the flange portion 53 of the fixing member 50.
It is desirable that the cover 70 be a resin molded product from the viewpoints of manufacturing, cost, corrosion resistance, etc. Also, it is desirable that the cover 70 be a resin molded product so as not to impede communication of the RFID tag 60.

(Step of attaching the fastening member 80)
Next, the fastening member 80 is attached.
FIG. 16 is a perspective view showing a state in which a fastening member 80 is attached to the state shown in FIG.
FIG. 17 is a cross-sectional view of the device 1 for detecting loosening of a rotary fastener in the process of being assembled, taken along the position of the arrows G--G in FIG.
The fastening member 80 is formed in a substantially cylindrical shape, and is inserted inside the rotating member 30, the fixed member 50, and the cover 70, and is fixed by screwing with the bolt 101. The fastening member 80 has a threaded portion 81, a flange portion 82, a fastening hole 83, and a through hole 84.

The threaded portion 81 is provided on the lower end side of the fastening member 80 and has a female thread formed therein, which is screwed into the excess length of the bolt 101 .
The flange portion 82 is provided on the upper end side of the fastening member 80 so as to expand in a flange shape, and presses against the upper surface portion 71 of the cover 70 .
The fastening hole 83 is provided through the flange portion 82 and is a hole for hooking a fastening tool when the threaded portion 81 is screwed into the excess length of the bolt 101 and fastened.
The through hole 84 passes through the center of the fastening member 80 and is connected to the threaded portion 81 .

By screwing the fastening member 80 having the above-mentioned configuration into the excess length of the bolt 101 and tightening it, the flange portion 82 presses the upper surface portion 71 of the cover 70 downward, and the upper surface portion 71 presses the upper surface portion 54 of the fixing member 50 downward. Furthermore, since the fixing member 50 presses the support base 20 downward, the support base 20 is pressed against the base member 110. Therefore, the fixing member 50 and the support base 20, and the support base 20 and the base member 110 are firmly fixed in close contact with each other using the excess length of the bolt 101, so that the fixing member 50 can be prevented from rotating even if vibration occurs.
Furthermore, a gap is provided between the upper end of the rotating member 30 and the upper surface 54 of the fixed member 50, and the two are not in contact with each other, so that the rotation of the rotating member 30 is not hindered by tightening the fastening member 80.

(Installation process of exterior material 230)
Finally, as the exterior material 230, for example, a polyester reinforcing fiber is covered, and a coating agent made of acrylic rubber elastic resin and ceramics is applied on top of it in layers of undercoat and undercoat. Furthermore, a topcoat agent mainly composed of acrylic silicone resin with excellent weather resistance is applied to impart waterproofing and block rainwater, ultraviolet rays, etc. from the outside, completing the rotating fastener loosening detection device 1 of this embodiment (see Figures 1 and 2). Note that in Figure 2, the exterior material 230 is shown as a single layer, but as described above, the exterior material 230 is composed of multiple layers. In addition, the exterior material 230 is not limited to the above-mentioned example configuration, and other materials with waterproofing properties, such as beechme-based materials, may be used.

(Rotary fastener loosening detection system)
FIG. 18 is a diagram showing an overview of a system for detecting loosening of a rotary fastener.
The rotary fastener loosening detection device 1 configured as described above can communicate with the RFID reader 500. Specifically, the RFID reader 500 communicates with the first RFID circuit 61 and the second RFID circuit 62 to receive information on whether the state detection wires 61c and 62c are cut or not. Then, the cut status of the state detection wires 61c and 62c can be obtained from the communication result of the RFID reader 500, and the degree of the loosening angle of the nut can be recognized in stages.

In addition, since the IC chips 61d, 62d of the rotary fastener loosening detection device 1 each have a unique ID, as shown in FIG. 18, the RFID reader 500 can communicate with multiple rotary fastener loosening detection devices 1 at once, and the loosening status can be managed for each ID later. This eliminates the need to record the position of each abnormal nut or bolt, as in the conventional tapping check, and allows for efficient confirmation of the status of the rotary fastener (whether it is loose or not).

(Vibration test)
A vibration test was carried out using the rotary fastener loosening detection device 1 configured as described above, and the results will be described below. The rotary fastener loosening detection device 1 of this embodiment is expected to be used, for example, to detect loosening of anchor bolts for highway lighting, etc. The vibration resistance test was carried out in accordance with the standards for lighting equipment in the test method established by the Japan Construction Electrical Technology Association (Road and Tunnel Lighting Equipment Specifications, Revised in 2018, Japan Construction Electrical Technology Association).
The vibration resistance test was carried out under conditions of a vibration frequency of 800 times/min and an amplitude of 3 mm for 5 minutes.
After the test, no peeling, cracks or other abnormalities were observed, and the test conditions were cleared. In addition, a communication test was conducted as a post-test, and communication was possible without any problems. In addition, after the test, the device was disassembled part by part, and no peeling or cracks were found in any of the components.

As described above, according to the rotary fastener loosening detection device 1 of this embodiment, loosening is detected based on the cutting status of the multiple state detection wires 61c and state detection wires 62c, so loosening can be detected in multiple stages according to the rotation angle of the rotating member 30, i.e., the rotation angle due to loosening of the rotary fastener. In addition, since it has a corrosion-resistant structure, it can effectively suppress corrosion of bolts and nuts.

(Modifications)
The present disclosure is not limited to the above-described embodiment, and various modifications and variations are possible, and these are also within the scope of the present disclosure.

(1) In the embodiment, a configuration including two state detection wirings, state detection wiring 61c and state detection wiring 62c, is exemplified. However, the present invention is not limited to this, and the number of state detection wirings may be three or more to increase the number of stages of loosening detection.

(2) In the embodiment, the RFID tag 60 is exemplified as having two RFID tag circuits, a first RFID circuit 61 and a second RFID circuit 62, assembled on a single substrate. However, the present invention is not limited to this, and may be configured as an RFID tag that can detect the disconnection of multiple state detection wirings using a single IC chip.

(3) In the embodiment, a configuration in which the cutting portion 40 is provided on the rotating member 30 and the RFID tag 60 is provided on the fixed member 50 is exemplified. This is not limited to the above, and for example, a configuration in which the RFID tag is provided on the rotating member and the cutting portion is provided on the fixed member may also be used.

The embodiments and variations may be used in any suitable combination, but detailed explanations will be omitted. Furthermore, the present disclosure is not limited to the embodiments described above.

1 Rotary fastener loosening detection device 10 Anti-vibration ring 20 Support base 30 Rotary member 31 Cutting portion mounting shape 32 Lower nut escape portion 33 Upper nut fitting portion 34 Gap portion 40 Cutting portion 41 Base portion 41a Screw hole 42 Cutting blade 50 Fixing member 51 Side opening 52 Slit 53 Flange portion 54 Top surface portion 55 Through hole 60 RFID tag 61 First RFID circuit 61a Antenna 61b Antenna 61c State detection wiring 61d IC chip 62 Second RFID circuit 62a Antenna 62b Antenna 62c State detection wiring 62d IC chip 70 Cover 71 Top surface portion 72 Through hole 80 Fastening member 81 Screw portion 82 Flange portion 83 Fastening hole 84 Through hole 101 Bolt 102 Nut 103 Nut 104 Washer 110 Base member 120 Base 210 Anticorrosive ring 220 Anticorrosive material 230 Outer material 500 RFID reader

Claims (11)

A rotating member that engages with the outer shape of the head of a bolt or the outer shape of a nut and is provided so as to be rotatable in accordance with the rotation of the bolt or the nut;
a fixed member disposed along the rotating member and fixed so as not to rotate with respect to the base;
an RFID tag having an antenna and a wiring for state detection;
Equipped with
The RFID tag is provided on one of the rotating member and the fixed member, and a cutting portion is provided on the other of the rotating member and the fixed member;
The cutting section is a device for detecting loosening of a rotary fastener that cuts the state detection wiring by rotating the rotating member. 2. The device for detecting loosening of a rotary fastener according to claim 1,
The state detection wiring is provided in plurality,
A device for detecting loosening of a rotary fastener, wherein the plurality of state detection wires are cut by the cutting portion at different rotation angles of the rotating member. The device for detecting loosening of a rotary fastener according to claim 1 or 2,
A device for detecting loosening of a rotary fastener, wherein the antenna is spaced from the bolt and the nut. The device for detecting loosening of a rotary fastener according to claim 1 or 2,
The rotating member engages with the outer shape of the nut and rotates in accordance with the rotation of the nut,
The bolt into which the nut is screwed is provided with an excess portion protruding from the nut,
A device for detecting loosening of a rotary fastener, wherein the fixing member is fixed to a base by utilizing the excess portion. The device for detecting loosening of a rotary fastener according to claim 1 or 2,
The RFID tag is a passive type. The device for detecting loosening of a rotary fastener according to claim 1 or 2,
A device for detecting loosening of a rotary fastener, wherein a sacrificial protective material is disposed in an inner area of the rotating member and the fixed member. The device for detecting loosening of a rotary fastener according to claim 1 or 2,
A device for detecting loosening of a rotary fastener, wherein the inner regions of the rotary member and the fixed member are filled with a petrolatum-based corrosion inhibitor. The device for detecting loosening of a rotary fastener according to claim 1 or 2,
a cover for covering the rotating member and the fixed member;
The outside of the cover is covered with a waterproof exterior material, thereby detecting loosening of a rotary fastener. A method for preventing corrosion of a rotary fastener in which the rotary fastener loosening detection device according to claim 1 or 2 is installed, comprising:
A method for preventing corrosion of a rotating fastener equipped with a device for detecting loosening of the rotating fastener, comprising filling the inner regions of the rotating member and the fixed member with a petrolatum-based corrosion-preventive agent. A method for preventing corrosion of a rotary fastener in which the rotary fastener loosening detection device according to claim 1 or 2 is installed, comprising:
a cover for covering the rotating member and the fixed member;
The corrosion prevention method for a rotary fastener equipped with a loosening detection device for a rotary fastener includes covering the outside of the cover with a waterproof exterior material. The rotary fastener loosening detection device according to claim 2 ;
an RFID reader that communicates with the RFID tag;
Equipped with
A system for detecting loosening of a rotary fastener, which recognizes the degree of loosening angle of the bolt or nut in stages from the communication results of the RFID reader.

Images