JP2016169997A - Slackening detection bolt and bolt slackening monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the fastened state of a bolt.SOLUTION: A slackening detection bolt 100 includes a bolt shaft member 10 having a shaft 11 and a head inner part 12, and a head outer member 20 having a hole part 21 fitted to the head inner part and a tool engaging part 22. In the protruded state of the shaft from a seat surface side opening 21b, the head outer member and the head inner part fit to each other so as to transmit fastening torque, transmit the axial force of a seat surface direction from the head inner part to the head outer member, and separate from each other in its reverse direction. For the axial connection part of the head inner part and the head outer part for transmitting the axial force, a contact area is changed according to the size of the axial force because of a change added to an axial position in the surface of the head inner part side (top surface of projected part 12b) or the surface of the head outer member side by the position of a direction perpendicular to the axial direction, and an electric characteristic value between these surfaces can be detected as a bolt slackening reference.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a looseness detection bolt and a bolt looseness monitoring system.

Preliminarily detecting leaks of fluids such as gases and liquids from piping in large-scale factory plants and maintaining the piping equipment before it leaks not only prevents serious accidents but also costs and man-hours for major repairs. It will also reduce.
However, it is difficult to detect this before the fluid leaks, and in fact, there are many cases where it is a reactive response by sensing a small amount of leaked fluid immediately after leaking.

In the flange fastening monitoring device described in Patent Literatures 1 and 2, a gasket interposed between a pair of flange portions fastened by fastening of fastening bolts in order to monitor fluid leakage from the flange fastening portion. In addition, a sensor such as a capacitance detection type or a pressure detection type is provided, and the fastening state is determined based on a signal from the sensor.
By this technology, it is possible to detect the leakage of fluid such as gas and liquid from the piping in a predictive manner and to maintain the piping equipment before the leakage.

JP 09-329281 A JP 2007-292628 A

However, in the inventions described in Patent Documents 1 and 2, the gap or pressure in the gasket is detected, and the looseness of the bolt is not directly detected.
By monitoring the fastening state of the bolts that are the fasteners, the fastening state of the true flange part can be understood, and further monitoring the fastening state of the bolts is not only for the safety of plant piping, but also for parts that cannot be visually confirmed in railway vehicles etc. It can be widely applied to the management of bolt tightening torque and the bolt tightening torque for steel towers located in the highland mountain forest.

  The present invention has been made in view of the above problems in the prior art, and it is an object of the present invention to constitute a loosening detection bolt and a bolt looseness monitoring system capable of accurately detecting the fastening state of a bolt.

The invention according to claim 1 for solving the above-described problem includes a bolt shaft member having a shaft portion and a head inner portion formed at a proximal end of the shaft portion;
A head outer member having a hole fitting with the head inner part and a tool engaging part formed on the outer periphery of the hole;
The hole portion is formed with a zenith side opening and a seat surface side opening, and is configured to be able to protrude from the seat surface side opening by inserting the shaft portion from the zenith side opening,
The head outer member and the head inner portion are fitted so that a fastening torque can be transmitted from the head outer member to the head inner portion in a state where the shaft portion protrudes from the seating surface side opening, and the head It is possible to transmit the axial force in the seating surface direction from the inner part to the head outer member and to fit in the opposite direction so as to be separated from each other,
An axial connection portion between the head inner portion and the head outer member for transmitting the axial force is a position in a direction perpendicular to the axial direction on the head inner portion side surface or the head outer member side surface. By changing the position in the axial direction by, the contact area for transmitting the axial force changes according to the magnitude of the axial force,
The loosening detection bolt is configured to be able to detect an electrical characteristic value between a surface on the head inner portion side and a surface on the head outer member side in the axial direction connecting portion as a bolt looseness reference.

  The invention according to claim 2 is the loosening detection bolt according to claim 1, wherein the electrical characteristic value is a contact resistance value or a capacitance value.

  According to a third aspect of the present invention, the axial connection portion includes a seating surface direction surface of a portion of the head inner portion protruding radially outward from the shaft portion, and an inner periphery of the hole portion of the head outer member. The loosening detection bolt according to claim 1 or 2, comprising a zenith-direction surface of a portion projecting radially inward from the surface.

  According to a fourth aspect of the present invention, the surface on the head inner portion side or the surface on the head outer member side in the axial direction connecting portion is formed on a zenith surface of a convex portion protruding in the axial direction, and the axis of the zenith surface The loosening detection bolt according to any one of claims 1 to 3, wherein the bolt is divided into a plurality of convex portions having different directional positions.

  The invention according to claim 5 is the looseness detecting bolt according to claim 4, wherein any one of the plurality of protrusions has an axial position of the zenith surface equal to that of at least two other protrusions. is there.

  According to a sixth aspect of the present invention, the plurality of convex portions include convex portions having different axial positions on the zenith surface, which are in contact with the mating surface at the lower limit of the practical fastening force range of the axial force. The loosening detection bolt according to Item 5.

  A seventh aspect of the present invention is the looseness detection bolt according to any one of the fourth to sixth aspects, wherein a connecting mating surface of the convex portion in the axial direction connecting portion is a bottom surface of the concave portion. .

  According to an eighth aspect of the present invention, in any one of the fourth to seventh aspects, a mediating layer having electrical characteristics is provided on the zenith surface of the convex portion or the connection counterpart surface in the axial direction connection portion. The loosening detection bolt described.

  According to a ninth aspect of the present invention, the bolt shaft member and the head outer member are connected to each other through an insulator that electrically insulates the bolt shaft member and the head outer member at a portion other than the connection portion through the intermediate layer. The loosening detection bolt according to claim 8, which is assembled.

  A tenth aspect of the present invention is the looseness detection bolt according to any one of the first to ninth aspects, wherein a measurement circuit for measuring the electrical characteristic value is attached.

  An eleventh aspect of the present invention is the loosening detection bolt according to the tenth aspect, further comprising a transmission circuit that transmits a measurement signal of the measurement circuit.

  A twelfth aspect of the present invention is the loosening detection bolt according to any one of the first to eleventh aspects, further comprising a dustproof cover that seals the zenith side opening.

The invention according to claim 13 includes a measurement circuit that measures the electrical characteristic value, a transmission circuit that transmits a measurement signal of the measurement circuit, and a dust-proof cover that seals the zenith side opening,
The measurement circuit and the transmission circuit are provided on the dust cover,
By attaching a dust cover for sealing the zenith side opening, two electrode terminals extended from the measurement circuit to measure the electrical characteristic value are connected to the head inner portion and the head outer member. The loosening detection bolt according to any one of claims 1 to 9, wherein the bolt is connected.

  The invention according to claim 14 is the loosening detection bolt according to claim 12 or 13, wherein the dust cover is fitted in the hole to seal the zenith side opening.

A fifteenth aspect of the invention is a loosening detection bolt according to any one of the first to fourteenth aspects,
A determination means for determining a fastening state of the looseness detection bolt based on an electrical characteristic value of the looseness detection bolt;
A bolt looseness monitoring system comprising: notifying means for notifying that the looseness detection bolt is in a predetermined loosened state based on the determination by the determining means.

The invention according to claim 16 is a memory in which the individual identification information assigned to each of the looseness detection bolts and the address information indicating the construction position of the bolt corresponding to the individual identification information on a one-to-one basis are registered. With means,
The bolt looseness monitoring system according to claim 15, wherein the address information of the looseness detection bolt related to the notification by the notification means can be output via a user interface.

  According to the present invention, it is possible to configure a looseness detection bolt and a bolt looseness monitoring system that can accurately detect the fastening state of the bolt.

It is a perspective view which shows the assembly completion state of the loosening detection volt | bolt which concerns on one Embodiment of this invention. It is a perspective view which shows the decomposition | disassembly state of the loosening detection bolt which concerns on one Embodiment of this invention. It is the perspective view which showed the decomposition | disassembly state of the loosening detection bolt which concerns on one Embodiment of this invention, and was seen from the angle different from FIG. It is a perspective view which shows the assembly process of the volt | bolt shaft member and insulation spacer of the loosening detection volt | bolt which concerns on one Embodiment of this invention. It is another perspective view which shows the assembly process of the volt | bolt shaft member and insulation spacer of the loosening detection volt | bolt which concerns on one Embodiment of this invention. It is a perspective view which shows the assembled state of the bolt shaft member and insulating spacer of the loosening detection bolt which concerns on one Embodiment of this invention. It is a perspective view which shows the assembly process of a head outer member with respect to the volt | bolt shaft member by which the insulation spacer of the loosening detection bolt which concerns on one Embodiment of this invention was assembled | attached. It is a perspective view which shows the assembled state of the bolt shaft member, insulation spacer, and head outer member of the looseness detection bolt which concerns on one Embodiment of this invention. It is a perspective view which looks up the head inner part of the bolt for looseness detection concerning one embodiment of the present invention. In accordance with an embodiment of the present invention, a diagram (a) in which the side surface of the head inner portion and the cross section of the head outer member are arranged coaxially, and the side surface of the head inner portion and the cross section passing through the concave portion of the head outer member in the circumferential direction. It is the figure (b) which drew the plane development. It is an exploded sectional view at the time of applying the bolt for looseness detection concerning one embodiment of the present invention to conclusion of a piping flange part. It is sectional drawing of the state which inserted and installed the bolt for looseness detection in the piping flange from the state of FIG. It is sectional drawing of the state which fastened the piping flange part from the state of FIG. 12 with the bolt and nut for looseness detection. It is a schematic diagram which shows the cross section of the dustproof cover of the loosening detection bolt which concerns on one Embodiment of this invention. It is a system configuration figure of a bolt looseness monitoring system concerning one embodiment of the present invention. Electrical circuit diagram (a) in the case where the measurement unit measures the contact resistance value in the looseness detection bolt according to one embodiment of the present invention, and a graph (b) showing a change in the resistance value over time after completion of the fastening It is. Electrical circuit diagram (a) when the measurement unit measures the capacitance value in the looseness detection bolt according to an embodiment of the present invention, and a graph showing the change in capacitance over time after completion of fastening ( b). It is a flowchart which shows an example of the flow of the process which a monitoring computer performs in the loosening monitoring system of the volt | bolt which concerns on one Embodiment of this invention.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

(Looseness detection bolt)
As shown in FIGS. 1 to 8, the looseness detection bolt 100 of this embodiment includes a bolt shaft member 10, a head outer member 20, an insulating spacer 30, and a dustproof cover 40. As shown in FIG. 1, the looseness detection bolt 100 is composed of a head 101 and a shaft portion 11 in the appearance at the time of completion of assembly, like a general bolt. In the head 101 portion, the zenith surface 101a of the head 101, the seat surface 23 disposed under the neck of the head 101, and the tool engaging portion 22 disposed on the outer periphery of the head 101 are exposed in appearance.

The bolt shaft member 10 includes a shaft portion 11 on which a screw is formed and a head inner portion 12 formed at the base end of the shaft portion 11. In the following description, the terms “axial direction”, “radial direction”, and “circumferential direction” refer to those based on the central axis of the shaft portion 11.
The head inner portion 12 has a portion 12a projecting radially outward from the shaft portion 11, and the portion 12a includes a fitting tooth 12a1 protruding in the radial direction and formed along the axial direction. A plurality of fitting teeth 12a1 are formed along the circumferential direction.
Moreover, the convex part 12b which protruded in the axial direction is formed in the seat surface direction end of each fitting tooth 12a1.

The head outer member 20 includes a hole portion 21 that fits with the head inner portion 12 and a tool engagement portion 22 formed on the outer peripheral portion of the hole portion 21.
In the present embodiment, the tool engaging portion 22 has a hexagonal shape, and a generally used tool such as a hexagon wrench can be applied. The engagement shape between the tool and the tool engagement portion may be special. The tool can be mechanically engaged with the tool engaging portion 22 and torque from the tool can be transmitted from the tool engaging portion 22 to rotate the bolt 100 about the axis.
The hole portion 21 is formed with a zenith side opening 21a and a seat surface side opening 21b, and is configured to be able to protrude from the seat surface side opening 21b by inserting the shaft portion 11 from the zenith side opening 21a.
The seating surface side opening 21 b is an opening surrounded by an inner flange portion 21 c provided on the seating surface side in the hole portion 21. The inner flange portion 21 c corresponds to a portion protruding radially inward from the inner peripheral surface of the hole portion 21 of the head outer member 20.
A concave portion 21d into which the convex portion 12b is inserted is formed on the top surface of the inner flange portion 21c corresponding to each convex portion 12b.

The insulating spacer 30 is a spacer member for holding the bolt shaft member 10 and the head outer member 20 in a predetermined concentric relative position, and electrically connects the bolt shaft member 10 and the head outer member 20. It is an insulator that insulates. However, the connection between the top surface 13 of the convex portion 12b and the bottom surface 24 of the concave portion 21d is excluded.
The insulating spacer 30 has a cylindrical shape as a whole.
Similar to the hole 21, the insulating spacer 30 is formed with a zenith side opening 31 a and a seat surface side opening 31 b, and is configured to be able to protrude from the seat surface side opening 31 b by inserting the shaft portion 11 from the zenith side opening 31 a. ing.
The seating surface side opening 31 b is an opening surrounded by an inner flange portion 31 c provided on the seating surface side in the insulating spacer 30. The inner flange portion 31 c corresponds to a portion projecting radially inward from the inner peripheral surface of the insulating spacer 30.
A hole portion 31d through which the convex portion 12b is inserted is formed on the top surface of the inner flange portion 31c corresponding to each convex portion 12b.
In the inner peripheral portion of the insulating spacer 30, a fitting groove 31e that fits the fitting tooth 12a1 is formed corresponding to each fitting tooth 12a1.
A peripheral wall rib 31f surrounding the periphery of the hole 31d is formed on the side surface of the inner flange 31c corresponding to a part of the hole 31d.

The dustproof cover 40 seals the zenith side opening 21a. After the head inner portion 12 and the insulating spacer 30 are accommodated in the hole portion 21, a space remains on the zenith side opening 21a side, and the dustproof cover 40 is pushed into this space. In this way, the dustproof cover 40 is fitted in the hole 21 and seals the zenith side opening 21a.
The dustproof cover 40 may be removed during the fastening operation or may be attached. Even if the dustproof cover 40 is attached, the dustproof cover 40 does not reach the outer diameter position of the head 101. Therefore, the dustproof cover 40 does not get in the way when the bolt 100 is fastened, and the dustproof cover 40 can be removed with a tool. Damage is prevented. In particular, the workability is good because the tool can be used without removing the dust cover 40 during the retightening operation when the bolt 100 is loosened.
The dust cover 40 is frictionally locked inside the hole 21. Even when the main bolt 100 is assembled before fastening, even when transportation or handling by an operator is performed, the main bolt 100 is prevented from being disassembled unexpectedly. It is also possible to perform fastening work with the main bolt 100 while assembling the main bolt 100, and it is also possible to attach the dustproof cover 40 after the fastening is completed.

As shown in FIGS. 9 and 10, the convex portion 12 b is provided with four types, three sets, and a total number of 12 with different positions in the axial direction of the zenith surface 13. The protrusions 12b1, 12b2, 12b3, and 12b4 are arranged in the circumferential direction in descending order of the amount of protrusion, and a total of twelve protrusions 12b are provided by repeating twice.
In the present embodiment, the four types of convex portions 12b1-4 having different positions of the zenith surface 13 protrude in the seating surface direction with the same position in the axial direction as a base. When the bearing surface direction is referred to as the bottom, the zenith surface 13 is arranged at a low position in the order of the convex portion 12b1, the convex portion 12b2, the convex portion 12b3, and the convex portion 12b4.
On the other hand, the concave portion 21d is also provided with the total number 12 corresponding to the convex portion 12b. The axial position of the bottom surface 24 of the recess 21d is the same.

11 to 13 show an example in which the present bolt 100 is applied to fastening of the pipe flanges 201 and 202 with the gasket 200 interposed therebetween. The insulating washer 203 is applied to block conduction between the bolt shaft member 10 and the head outer member 20 via the piping flange 201. In addition, a washer 204 and a nut 205 are applied. The application destination of the bolt 100 is not particularly limited.
As shown in FIG. 13, when the bolt 100 is fastened, the convex portion 12b is inserted and protrudes through the hole portion 31d of the inner flange portion 31c, and the peripheral wall rib 31f surrounding the hole portion 31d is formed in the concave portion 21d. Fit. Further, the fitting teeth 12 a 1 of the head inner portion 12 are fitted in the fitting grooves 31 e of the insulating spacer 30.
Since the peripheral wall rib 31f is interposed between the outer periphery of the convex portion 12b and the concave portion 21d, the outer peripheral surface of the convex portion 12b and the inner peripheral surface of the concave portion 21d are not in contact with each other even when a fastening torque is applied. Retained. Further, the outer peripheral surface of the convex portion 12b protruding from the hole portion 31d not provided with the peripheral wall rib 31f is also not in contact with the inner peripheral surface of the concave portion 21d because a gap is maintained. The peripheral wall ribs 31f may be provided for all the holes 31d, or may be provided for some of the holes 31d. When providing the peripheral wall rib 31f with respect to the one part hole part 31d, it is preferable to disperse | distribute in the circumferential direction as at least three.
As described above, the head outer member 20 and the head inner portion 12 are fitted so that the fastening torque can be transmitted from the head outer member 20 to the head inner portion 12 with the shaft portion 11 protruding from the seating surface side opening 21b. To do. As a result, the entire bolt 100 can be rotated by mechanically engaging the tool with the tool engaging portion 22.
Further, the zenith surface 13 of the convex portion 12b contacts the bottom surface 24 of the concave portion 21d. In other words, the axial force in the seating surface direction can be transmitted from the head inner portion 12 to the head outer member 20, and they are fitted so as to be separated from each other in the opposite direction.

In the present embodiment, the axial direction connecting portion between the head inner portion 12 and the head outer member 20 for transmitting the axial force is constituted by a pair of a convex portion 12b and a concave portion 21d. The zenith surface 13 (the bearing surface direction surface of the main bolt 100) of the convex portion 12b is a surface on the head inner portion 12 side in the axial connection portion, and the bottom surface 24 (the zenith direction surface of the main bolt 100) of the concave portion 21d is It is the surface on the head outer member 20 side in the axial direction connecting portion.
As described above, the zenith surface 13 (the surface on the head inner portion side) of the convex portion 12b is changed in the axial position depending on the position in the direction perpendicular to the axial direction. As a result, the contact area for transmitting the axial force changes according to the magnitude of the axial force.
When the fastening is completed, the zenith surface 13 of all the convex portions 12b comes into contact with the bottom surface 24 of the concave portion 21d with a pressing force by the compression elastic deformation of the convex portions 12b. In other words, under the initial fastening force at the completion of fastening, the material of the bolt shaft member 10 and the breaking of the convex portion 12b are made so that the zenith surface 13 of all the convex portions 12b contacts the bottom surface 24 of the concave portion 21d with a pressing force. Area, protrusion amount, difference in protrusion amount, etc. are designed.
As the loosening of the bolt 100 proceeds, the axial force decreases, and the convex portion 12b4 having the highest zenith surface 13 moves away from the bottom surface 24 of the concave portion 21d, and thereafter the convex portion 12b3, the convex portion 12b2,. The surface 13 is separated in descending order, and the contact area for transmitting the axial force changes stepwise.

  The three convex portions 12b1, the three convex portions 12b2, the three convex portions 12b3, and the three convex portions 12b4 have the same axial position of the zenith surface 13. Accordingly, any one of the total number 12 of the convex portions 12b (for example, the convex portion 12b1) has at least two other convex portions (the other two convex portions 12b1 and 12b1) in the axial direction of the zenith surface 13. ). The three axial positions of the zenith surface 13 that are equal in position are dispersed in the circumferential direction, so that uniform axial force transmission is possible.

The bolt shaft member 10 and the head outer member 20 are made of a metal material (conductive material) such as steel or stainless steel.
A mediating layer having predetermined electrical characteristics (resistance value and dielectric constant) is provided on the top surface 13 of each convex portion 12b or the bottom surface 24 of the concave portion 21d. Examples of the method of providing such a mediating layer include a method of performing an oxide film treatment on the zenith surface 13 of the convex portion 12b, and a method of attaching a sheet-like resistance material or insulating material to the zenith surface 13 of the convex portion 12b.
Therefore, a resistive element or a capacitive element can be formed between the convex portion 12b1 and the concave portion 21d.
In view of the above, the bolt 100 is configured such that one of the measurement terminals of the electrical characteristic value measuring instrument is brought into contact with the head inner portion 12 and the other is brought into contact with the head outer member 20, so (Capacitance value) can be detected as a bolt looseness reference. That is, the bolt 100 has an electrical characteristic value (contact resistance value) between the surface on the head inner portion 12 side and the surface on the head outer member 20 side in the axial connection portion between the head inner portion 12 and the head outer member 20. (Capacitance value) can be detected as a bolt looseness reference.
In addition, about the pair of the above convex part 12b1 and the recessed part 21d, you may replace each other, ie, provide a convex part in the head outer member 20, and provide a recessed part in the head inner part 12.

In order to acquire the function of transmitting the detected value by itself, the present bolt 100 has a measurement transmission circuit 50.
As shown in FIG. 14, the measurement transmission circuit 50 is provided in a form built in the dust cover 40. The measurement transmission circuit 50 includes a measurement unit 51, a transmission unit 52, and two electrode terminals 53 and 54 extending from the measurement unit 51. More specifically, as shown in FIG. 15, the measurement transmission circuit 50 includes a measurement unit 51, a transmission unit 52, two electrode terminals 53 and 54 extending from the measurement unit 51, a battery 55, and a control unit 56. And have. The measurement unit 51 corresponds to a measurement circuit that measures the above-described electrical characteristic value, and the transmission unit 52 corresponds to a transmission circuit that transmits the measurement signal.
Two electrode terminals 53 and 54 are connected to the head inner portion 12 and the head outer member 20 by mounting the dustproof cover 40 for sealing the zenith side opening 21a. Therefore, the electrical connection work of the dust cover 40 is simple. The electrode terminal 53 is a terminal connected to the head inner portion 12 and is provided on the bottom surface of the dust cover 40. The electrode terminal 54 is a terminal connected to the head outer member 20 and is provided on the side surface of the dust cover 40.

(Measurement principle and alert setting)
Further, with reference to FIG. 16 and FIG. 17, the measurement principle of the electrical characteristic value that is a reference for loosening the bolt and the alert setting will be described.
FIG. 16A is an electric circuit diagram when the measurement unit 51 measures the contact resistance value in the bolt 100. It shows that each electrical resistance relates to the convex part 12b1, the convex part 12b2, the convex part 12b3, and the convex part 12b4. This corresponds to the switch SW1 being turned on when the zenith surface 13 of the convex part 12b1 and the bottom surface 24 of the concave part 21d are connected via the intermediate resistance layer, and turned off when leaving. Switches corresponding to the convex portion 12b1, the convex portion 12b3, and the convex portion 12b4 are a switch SW2, a switch SW3, and a switch SW4 in this order.
Immediately after the fastening operation of the bolt 100 is completed, the zenith surface 13 of all the convex portions 12b1-4 is connected to the bottom surface 24 of the counterpart concave portion 21d via the intermediate resistance layer, and all the switches SW1-4 are ON. . As the loosening of the bolt 100 progresses over time, the fastening force (axial force) decreases. First, the zenith surface 13 of the convex portion 12b4 moves away from the bottom surface 24 of the concave portion 21d, and then the convex portion 12b3 and the next. The convex portion 12b2 and finally the convex portion 12b1 are separated. The switches are turned OFF in the order of switch SW4, switch SW3, switch SW2, and switch SW1. Accordingly, the resistance value is gradually increased because it is proportional to the cross-sectional area of electrical conduction. This is shown in the graph as shown in FIG. As shown in FIG. 16B, the resistance value changes stepwise according to the step change of the contact area of the zenith surface 13.

In FIG. 16B, level Lv1 is the resistance level when all switches SW1-4 are ON, level Lv2 is the resistance level when only 3 switches SW1-3 are ON, and level Lv3 is only 2 switches SW1-2 ON The level Lv4 indicates the resistance level when only one switch SW1 is ON.
It can be said that the tightening force of the bolt 100 is higher as the number of the level LV1-4 is smaller, and the looseness of the bolt 100 is more advanced as the number of the level LV1-4 is larger.
When the case where the measurement unit 51 measures the contact resistance value is replaced with the case where the measurement unit 51 measures the capacitance value, the result is as shown in FIG. Even if the capacitance value is replaced, the capacitance value changes stepwise as shown in FIG. 17B according to the step change of the contact area of the zenith surface 13.

As an alert setting in the bolt looseness monitoring system described below, for example, it is conceivable to set an inspection maintenance advisory alert at levels Lv2 to LV3 and an operation stop alert at level Lv4. Various types of warning levels can be set.
At least the level Lv1 to the level LV2 are designed to be within the practical fastening force range of the fastening force (axial force). That is, the lower limit of the practical fastening force range is set to the fastening force at level LV2 or lower. That is, in the present embodiment, the total number 12 of the convex portions 12b are in contact with the mating surface at the lower limit of the practical fastening force range of the fastening force (axial force), and are a plurality of convex portions 12b1 having different axial positions of the zenith surface 13. -3. Thereby, the progress of the loosening of the bolt can be detected step by step within the practical fastening force range, and a dangerous state that falls below the practical fastening force range can be avoided and the bolt can be retightened beforehand. The level Lv1 to the level LV3 may be within the practical fastening force range.

(Bolt loosening monitoring system)
Next, a bolt looseness monitoring system will be described.
As shown in FIG. 15, the bolt looseness monitoring system 300 of this embodiment includes a plurality of looseness detection bolts 100, a relay device 310 that receives a radio signal from the detection bolt 100, and a bidirectional communication with the relay device 310. And a monitoring computer 320 connected by a communication cable.
Individual identification information (ID) is assigned to each loosening detection bolt 100. It is registered in a storage unit included in the control unit 56. Registered in the storage unit (storage means) included in the monitoring computer 320 is individual identification information (ID) and address information indicating the construction position of the bolt having the ID corresponding to the individual identification information (ID) on a one-to-one basis. Has been.
The relay device 310 includes a reception unit 311 (reception unit) that receives the ID and electrical characteristic value of the looseness detection bolt 100, a control unit 312, a storage unit 313, a transmission / reception unit 314, and a power supply unit 315. Prepare. Power is supplied from the power supply device 330 to the relay device 310, and power is supplied to each unit of the relay device 310 via the power supply unit 315. The control unit 312 functions under the execution of the program stored in the storage unit 313, reads the signal received by the reception unit 311 and transmits it to the monitoring computer 320 via the transmission / reception unit 314 and the bidirectional communication cable. Then, the slack detection bolt 100 and the monitoring computer 320 are relayed.

The control unit 56 of each loosening detection bolt 100 digitally encodes the measurement value and ID indicated by the measurement unit 51 and periodically transmits them through the transmission unit 52. This transmission signal is input to the monitoring computer 320 via the relay device 310.
Based on the input measurement value, the monitoring computer 320 has determination means for determining the fastening state of the detection bolt 100 related to the ID attached to the measurement value, and detection related to the ID based on the determination of the determination means. Informing means for informing that the working bolt 100 is in a predetermined loose state is constituted by the operation of the program on the processor. Moreover, the monitoring computer 320 reads the address information corresponding to the ID.
And the monitoring computer 320 performs the determination process and alerting | reporting process of a fastening state, as shown, for example in the flowchart shown in FIG.
The flow shown in FIG. 18 will be described.
When there is an input of ID and measurement value (step S1), the monitoring computer 320 reads the address information corresponding to the ID (step S2), and determines whether or not the fastening state is level LV4 or less (step S3).
If YES in step S3, an operation stop alert is output including the ID and address information (step S4). The output is executed by a user interface such as a video monitor or an audio monitor provided in the monitoring computer 320, or a user interface such as a video monitor or an audio monitor of another computer connected to the monitoring computer 320. At least one of the other computers is installed in the inspection / repair department of machinery and equipment constructed using the bolts 100. Alert information is transmitted from the monitoring computer 320 to other computers.
When the monitoring computer 320 has a function of automatic operation stop control, the operation stop alert includes a gist that “operation has been stopped” and other information such as a coping method. When the monitoring computer 320 does not have an automatic operation stop control function, the operation stop alert includes a gist that “Please stop operation” and other information such as a coping method.

If NO in step S3, it is determined whether the engaged state is level LV3 or less (step S5).
If YES in step S5, an inspection maintenance advisory alert including the ID and address information is output (step S6). This inspection / maintenance advisory alert includes a level LV3.
Workers in the inspection / repair department immediately go to the site by relying on the address information, identify the problem bolt 100, and retighten or replace it with a new bolt 100 if necessary. To complete.
The address information may be presented in any embodiment, such as displaying the problematic bolt 100 prominently on a 3D map including the target machine and equipment.

If NO in step S5, it is determined whether the engaged state is level LV2 or less (step S7).
If YES in step S5, an inspection maintenance advisory alert including the ID and address information is output (step S8). This inspection / maintenance advisory alert includes a level LV2.
The worker in the inspection / repair department, for example, identifies the problematic bolt 100 by relying on the address information during periodic inspection, and retightens it or replaces it with a new bolt 100 when replacement is necessary. Complete.

In addition, the worker who performs the fastening operation of the new bolt 100 at the initial time and replacement reads the ID of the new bolt 100 using the information input communication terminal, sets the address information, and transmits it to the monitoring computer 320. In response, the monitoring computer 320 registers the address information in association with the ID.
In addition, the determination unit is provided in the control unit 51 in the dust cover 40, that is, the determination values S 3, S 5, and S 7 are performed by the control unit 51 in the dust cover 40 and transmitted to the monitoring computer 320. May be a signal for discriminating the four stages of LV1 to Lv4. In that case, the transmission from the control unit 51 is programmed to be executed at the time of initial setting and when there is a level change.

  In the above embodiment, the axial position of the zenith surface 13 of the convex portion 12b is changed depending on the circumferential position. Regardless of this, a plurality of convex portions may be arranged in the radial direction, and the axial position of the zenith surface 13 of the convex portion 12b may be changed depending on the radial position. In order to form a large number of concave portions in the outer diameter of the head 101, it is preferable to change the axial position of the zenith surface 13 of the convex portion 12b depending on the circumferential position.

10 bolt shaft member 11 shaft portion 12 head inner portion 12a1 fitting tooth 12b (12b1-4) convex portion 13 zenith surface 20 of the convex portion head outer member 21 hole portion 21a zenith side opening 21b seat surface side opening 21c inner flange portion 21d Recess 22 Tool engaging portion 23 Seat surface 24 Bottom surface 30 of the recess Insulating spacer 31a Zenith side opening 31b Seat surface side opening 31c Inner flange portion 31d Hole portion 31e Fitting groove 31f Perimeter wall rib 40 Dustproof cover 50 Measurement transmission circuit 51 Measurement portion 52 Transmitter 53, 54 Electrode terminal 100 Loosening detection bolt 101 Head 101a Head zenith surface 200 Gasket 201 Piping flange 202 Piping flange 203 Insulating washer 204 Washer 205 Nut 300 Bolt looseness monitoring system 310 Relay device 320 Monitoring computer

Claims (16)

A bolt shaft member having a shaft portion and a head inner portion formed at the base end of the shaft portion;
A head outer member having a hole fitting with the head inner part and a tool engaging part formed on the outer periphery of the hole;
The hole portion is formed with a zenith side opening and a seat surface side opening, and is configured to be able to protrude from the seat surface side opening by inserting the shaft portion from the zenith side opening,
The head outer member and the head inner portion are fitted so that a fastening torque can be transmitted from the head outer member to the head inner portion in a state where the shaft portion protrudes from the seating surface side opening, and the head It is possible to transmit the axial force in the seating surface direction from the inner part to the head outer member and to fit in the opposite direction so as to be separated from each other,
An axial connection portion between the head inner portion and the head outer member for transmitting the axial force is a position in a direction perpendicular to the axial direction on the head inner portion side surface or the head outer member side surface. By changing the position in the axial direction by, the contact area for transmitting the axial force changes according to the magnitude of the axial force,
A looseness detection bolt that can detect an electrical characteristic value between a surface on the head inner portion side and a surface on the head outer member side in the axial direction connecting portion as a bolt looseness reference.   The loosening detection bolt according to claim 1, wherein the electrical characteristic value is a contact resistance value or a capacitance value.   The axial connection portion projects radially inward from the seat surface direction surface of the portion of the head inner portion that projects radially outward from the shaft portion and the inner peripheral surface of the hole of the head outer member. The loosening detection bolt according to claim 1 or 2, wherein the bolt is configured by a zenith direction surface of the portion.   The head inner portion side surface or the head outer member side surface in the axial direction connecting portion is formed on the zenith surface of the convex portion protruding in the axial direction, and a plurality of projections having different axial positions of the zenith surface The loosening detection bolt according to any one of claims 1 to 3, which is divided into parts.   The looseness detection bolt according to claim 4, wherein any one of the plurality of convex portions has a position in the axial direction of the zenith surface equal to that of at least two other convex portions.   6. The looseness detection according to claim 4, wherein the plurality of convex portions include convex portions that are in contact with a mating surface at a lower limit of a practical fastening force range of the axial force and have different positions in the axial direction of the zenith surface. bolt.   The loosening detection bolt according to any one of claims 4 to 6, wherein a connecting counterpart surface of the convex portion in the axial direction connecting portion is a bottom surface of the concave portion.   The loosening detection bolt according to any one of claims 4 to 7, wherein a mediating layer having electrical characteristics is provided on a zenith surface of the convex portion or a connection counterpart surface thereof in the axial connection portion.   9. The bolt shaft member and the head outer member are assembled through an insulator that electrically insulates the bolt shaft member and the head outer member at a portion other than a connection portion through the mediating layer. Bolt for detecting looseness.   The loosening detection bolt according to any one of claims 1 to 9, further comprising a measurement circuit that measures the electrical characteristic value.   The loosening detection bolt according to claim 10, further comprising a transmission circuit that transmits a measurement signal of the measurement circuit.   The loosening detection bolt according to any one of claims 1 to 11, further comprising a dustproof cover that seals the zenith side opening. A measurement circuit for measuring the electrical characteristic value, a transmission circuit for transmitting a measurement signal of the measurement circuit, and a dustproof cover for sealing the zenith side opening,
The measurement circuit and the transmission circuit are provided on the dust cover,
By attaching a dust cover for sealing the zenith side opening, two electrode terminals extended from the measurement circuit to measure the electrical characteristic value are connected to the head inner portion and the head outer member. The loosening detection bolt according to any one of claims 1 to 9, wherein the bolt is connected.   The loosening detection bolt according to claim 12 or 13, wherein the dust cover is fitted in the hole to seal the zenith side opening. A loosening detection bolt according to any one of claims 1 to 14,
A determination means for determining a fastening state of the looseness detection bolt based on an electrical characteristic value of the looseness detection bolt;
A bolt looseness monitoring system comprising: notifying means for notifying that the looseness detection bolt is in a predetermined loosened state based on the determination by the determining means. The storage means in which the individual identification information assigned to each of the bolts for looseness detection and the address information indicating the construction position of the bolt corresponding to the individual identification information one to one are registered,
The bolt looseness monitoring system according to claim 15, wherein address information of the looseness detection bolt related to the notification by the notification means can be output via a user interface.

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