In-situ preparation method of eddy current sensor, bolted joint and eddy current sensor monitoring system

Abstract

The application discloses an in-situ preparation method of an eddy current sensor, a bolt connecting piece and an eddy current sensor monitoring system, and relates to the technical field of structural health monitoring. The in-situ preparation method is used for preparing the eddy current sensor on the outer periphery of the bolt; the eddy current sensor comprises N layers of eddy current coils and N+1 layers of insulating layers; the bolt comprises a screw rod segment and a light rod segment; and the in-situ preparation method comprises the following steps: S120, solidifying a first insulating layer on the outer periphery of the light rod segment to cover the light rod segment; S140, arranging an i-th mask layer on the outer periphery of an i-th insulating layer, wherein the i-th mask layer is provided with a target pattern hollow hole; S160, solidifying an i-th eddy current coil in the target pattern hollow hole to be fixed to the i-th insulating layer, wherein the i-th eddy current coil is provided with a first electrode lead-out end and a second electrode lead-out end, 1≤i≤N, and i and N are positive integers; and S180, solidifying an i+1-th insulating layer on the i-th insulating layer. The technical scheme can improve the integration of the eddy current sensor and the bolt.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structural health monitoring, in particular to an in-situ preparation method of an eddy current sensor, a bolted joint and an eddy current sensor monitoring system. BACKGROUND

[0002] The bolted joint structure is the main mechanical connection method of the composite material structure of the aircraft, and has the advantages of high reliability and strong load bearing capacity. In specific implementation, the bolted joint structure generally includes a bolted joint and media bodies of different layers, and the bolted joint is arranged at a bolt hole of the media bodies of different layers to connect the media bodies of different layers.

[0003] Because the media bodies of different layers, such as plate-shaped media bodies, bear large loads and stress concentrations at the bolt holes, the bolt hole parts become the second most common damage starting position leading to major accidents of the aircraft. At the same time, the damage forms of the bolted joint structure are complex and diverse, including bolt loosening, hole edge cracking, net section loss, etc., and the main failure modes include extrusion failure, tensile failure, shear failure, etc. Therefore, intelligent real-time monitoring of the bolted joint structure has great significance for ensuring the safety and structural integrity of the aircraft.

[0004] The eddy current detection technology is a non-destructive detection technology based on the principle of electromagnetic induction, which has the advantages of fast detection speed, non-contact, low detection cost, and can detect the structure below the surface, and is widely used in the health monitoring of the bolted joint structure. The common structure for realizing the eddy current detection technology is an eddy current sensor, which identifies defects by detecting the electromagnetic field disturbance caused by the eddy current, that is, when the eddy current sensor is close to the measured material, the excitation magnetic field generated by the alternating current flowing through the excitation coil will produce an induced eddy current in the material, and the induced eddy current will produce an induced magnetic field, and the existence of defects will change the distribution form of the induced eddy current, causing disturbance of the induced magnetic field, and then changing the impedance and electromotive force of the receiving coil. However, the eddy current coil of the traditional eddy current sensor is large in size and cannot realize online monitoring.

[0005] Some preparation methods and applications of flexible eddy current sensors with strong structural adaptability have been reported in recent existing literatures, such as a flexible two-dimensional eddy current array sensor formed by flexible circuit printing technology. The eddy current sensor is connected to the outer periphery of the bolt in a pasting manner during use to realize online monitoring, but the integration of the eddy current sensor and the bolt is low.

[0006] Therefore, how to improve the integration of the eddy current sensor and the bolt is still a technical problem to be solved by those skilled in the art. SUMMARY

[0007] In view of this, in order to solve the above technical problems, the application provides an in-situ preparation method of an eddy current sensor, a bolt connection piece, and an eddy current sensor monitoring system.

[0008] In order to achieve the above technical problems, one of the technical solutions adopted by the application provides an in-situ preparation method of an eddy current sensor, which is used to prepare the eddy current sensor in-situ on the outer periphery of a bolt. The eddy current sensor comprises N layers of eddy current coils and N+1 layers of insulating layers, where N is a positive integer. The bolt comprises a screw rod segment and a light rod segment. The in-situ preparation method comprises the following steps:

[0009] Step S120: solidifying a first insulating layer on the outer periphery of the light rod segment to cover the light rod segment;

[0010] Step S140: arranging an i-th mask layer on the outer periphery of the i-th insulating layer, the i-th mask layer being provided with a target pattern hollow hole, the pattern shape of the target pattern hollow hole being adapted to the outer shape of the i-th eddy current coil;

[0011] Step S160: solidifying the i-th eddy current coil in the target pattern hollow hole to fix the i-th eddy current coil to the i-th insulating layer, the i-th eddy current coil having a first electrode lead-out end and a second electrode lead-out end, 1≤i≤N and i being a positive integer;

[0012] Step S180: solidifying an i+1-th insulating layer on the i-th insulating layer to cover the i-th eddy current coil and avoid the first electrode lead-out end and the second electrode lead-out end of the i-th eddy current coil.

[0013] In order to solve the above technical problems, another technical solution adopted by the application is to provide a bolt connection piece, which comprises a bolt and an eddy current sensor. The eddy current sensor comprises N layers of eddy current coils and N+1 layers of insulating layers. The bolt comprises a screw rod segment and a light rod segment. The eddy current sensor is prepared in-situ on the outer periphery of the bolt by using the above in-situ preparation method.

[0014] In order to solve the above technical problems, another technical solution adopted by the application is to provide an eddy current sensor monitoring system, which at least comprises:

[0015] A bolt connection piece, which is the above bolt connection piece, and is used to be arranged at a bolt hole of a medium body at different layers to connect the medium bodies at different layers;

[0016] An excitation source, which is electrically connected to at least part of the first electrode lead-out ends and the second electrode lead-out ends of the N layers of eddy current coils of the bolt connection piece, respectively;

[0017] An electrical signal analyzer, which is electrically connected to at least part of the first electrode lead-out ends and the second electrode lead-out ends of the N layers of eddy current coils of the bolt connection piece, respectively;

[0018] The excitation source is configured to apply alternating current to the eddy current coils of at least some of the layers to cause the corresponding eddy current coils to generate corresponding excitation magnetic fields; the composite material layers of the outer periphery of the bolt hole are capable of generating corresponding induced magnetic fields corresponding to the damage states of the composite material layers under the action of the excitation magnetic fields; the eddy current coils of at least some of the layers have corresponding induced electric signals based on the action of the induced magnetic fields; and the electric signal analyzer is configured to monitor the induced electric signals of the eddy current coils of at least some of the layers based on the action of the induced magnetic fields.

[0019] Beneficial effects: the prior art scheme has the following disadvantages: the eddy current sensor is attached to the bolt, and the integration degree of the eddy current sensor and the bolt is low; compared with the prior art scheme, the technical scheme of the present application has the advantages that the eddy current sensor can be prepared in situ on the bolt, and the integration degree of the eddy current sensor and the bolt is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flowchart of the in-situ preparation method of the eddy current sensor of the first embodiment of the present application;

[0021] Figure 2 is a schematic diagram of the implementation scene of the in-situ preparation method of the eddy current sensor of the first embodiment, the fourth embodiment, the sixth embodiment and the seventh embodiment of the present application, Figure 2 The eddy current coils of the eddy current sensor are shown as the back-to-back coils distributed on the cylindrical surface of the outer periphery of the i-th insulating layer;

[0022] Figure 3 is a cross-sectional view of the structure formed after step S120 of the in-situ preparation method of the eddy current sensor of the first embodiment, the fourth embodiment, the sixth embodiment and the seventh embodiment of the present application, Figure 3 Only the structure of the area corresponding to the polished rod section is shown, and the structure of the area corresponding to the screw rod section is not shown;

[0023] Figure 4 is a cross-sectional view of the structure formed after step S140 of the in-situ preparation method of the eddy current sensor of the first embodiment, the fourth embodiment, the sixth embodiment and the seventh embodiment of the present application, Figure 4 Only the structure of the area corresponding to the polished rod section is shown, and the structure of the area corresponding to the screw rod section is not shown;

[0024] Figure 5 is a cross-sectional view of the structure formed after step S160 of the in-situ preparation method of the eddy current sensor of the first embodiment, the fourth embodiment, the sixth embodiment and the seventh embodiment of the present application, Figure 5 Only the structure of the area corresponding to the polished rod section is shown, and the structure of the area corresponding to the screw rod section is not shown;

[0025] Figure 6is a cross-sectional view of the structure formed after step S170 in the in-situ preparation method of the vortex sensor of the first embodiment, the fourth embodiment, the sixth embodiment, and the seventh embodiment, Figure 6 Only the structure of the region corresponding to the polished rod section is shown, and the structure of the region corresponding to the screw rod section is not shown.

[0026] Figure 7 is a perspective view of the structure formed after step S170 in the in-situ preparation method of the vortex sensor of the first embodiment, the fourth embodiment, the sixth embodiment, and the seventh embodiment,

[0027] Figure 8 is a cross-sectional view of the structure formed after step S180 in the in-situ preparation method of the vortex sensor of the first embodiment, the fourth embodiment, the sixth embodiment, and the seventh embodiment, Figure 8 Only the structure of the region corresponding to the polished rod section is shown, and the structure of the region corresponding to the screw rod section is not shown.

[0028] Figure 9 is a cross-sectional view of the structure formed after step S200 in the in-situ preparation method of the vortex sensor of the sixth embodiment, Figure 9 Only the structure of the region corresponding to the polished rod section is shown, and the structure of the region corresponding to the screw rod section is not shown.

[0029] Figure 10 is a cross-sectional view of the mask plate used in step S140 in the in-situ preparation method of the vortex sensor of the first embodiment, the fourth embodiment, the sixth embodiment, and the seventh embodiment, Figure 10 The flexible substrate in the mask plate in the above is in a first state;

[0030] Figure 11 is a perspective view of the structure formed after step S170 in the in-situ preparation method of the vortex sensor of the eighth embodiment,

[0031] Figure 12 is a cross-sectional view of the structure formed after step S170 in the in-situ preparation method of the vortex sensor of the eighth embodiment, Figure 12 Only the structure of the region corresponding to the polished rod section is shown, and the structure of the region corresponding to the screw rod section is not shown.

[0032] Figure 13 is a top view of the mask plate used in step S140 in the in-situ preparation method of the vortex sensor of the eighth embodiment, Figure 13 The flexible substrate in the mask plate in the above is in a first state;

[0033] Figure 14 is a cross-sectional view of the structure formed after step S200 in the in-situ preparation method of the vortex sensor of the eighth embodiment,Figure 14 Only the structure of the area corresponding to the polished rod section is shown, and the structure of the area corresponding to the screw rod section is not shown;

[0034] Figure 15 is a sectional view of a mask plate used in step S140 in the in-situ preparation method of the vortex sensor of the eighth embodiment, Figure 15 The flexible substrate in the mask plate in is in a first state;

[0035] Figure 16 is a schematic diagram of an implementation scenario of step S1431 in the in-situ preparation method of the vortex sensor of the eighth embodiment;

[0036] Figure 17 is a schematic diagram of a circuit module of the vortex sensor monitoring system of the present application;

[0037] Figure 18 is a schematic diagram of the structure of the vortex sensor monitoring system of the present application.

[0038] Explanation of reference signs:

[0039] 10 vortex sensor monitoring system; bolt connecting piece 100; excitation source 200; electric signal analyzer 300; medium body 20; bolt hole 30; sintering furnace 40; polishing machine 50; support seat 51; belt polishing mechanism 52; driving device 53; annular polishing belt 54; mask plate 60; adhesive layer 61; flexible substrate 62; target pattern hollow hole 63a; pre-set pattern hollow hole 63b; multimeter 70; laser cutting device 80; integrated device 90; first angle β;

[0040] Bolt 110; polished rod section 111; screw rod section 112; vortex sensor 120; insulating layer 121; vortex coil 122; hui-shaped coil 122a; spiral coil 122b; first electrode lead-out end 123; second electrode lead-out end 124; first electrode lead-out wire 125; second electrode lead-out wire 126; first ceramic sheet 127; second ceramic sheet 128; first solidified connecting part 129; second solidified connecting part 130. DETAILED DESCRIPTION

[0041] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be described in further detail below in conjunction with the drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application.

[0042] First embodiment

[0043] Please refer to Figure 1、 Figure 2 and Figure 9 The present application provides an in-situ fabrication method for an eddy current sensor 120. The in-situ fabrication method is used to fabricate the eddy current sensor 120 in situ on the periphery of a bolt 110. The eddy current sensor 120 includes N layers of eddy current coils 122 and N+1 layers of insulation layers 121, where N is a positive integer. The N layers of eddy current coils 122 are divided into the first eddy current coil 122 through the Nth eddy current coil 122, and the N+1 layers of insulation layers 121 are divided into the first insulation layer 121 through the N+1th insulation layer 121. The bolt 110 includes a polished rod section 111 and a screw rod section 112.

[0044] Optionally, in order to facilitate miniaturization of the eddy current sensor 120 , N may be less than or equal to 5, but is not limited thereto. In other embodiments, N may also be greater than 5.

[0045] The first embodiment of the in-situ preparation method includes step S120 , step S140 , step S160 , and step S180 .

[0046] Combine Figure 1 and Figure 3 See Figure 2 As shown, step S120 : solidifying the outer periphery of the polished rod segment 111 to form a first insulating layer 121 covering the polished rod segment 111 .

[0047] To insulate the subsequently installed first eddy current coil 122 from the polished rod segment 111, an insulating layer 121 is required to be applied to the outer periphery of the polished rod segment 111. Step S120 allows the first insulating layer 121 to be fabricated in situ on the polished rod segment 111, thereby ensuring a high degree of bonding and integration between the first insulating layer and the polished rod segment 111. Optionally, step S120 includes steps S121 and S122.

[0048] Step S121 : placing a first dielectric slurry on the outer periphery of the polished rod segment 111 . The first dielectric slurry is used to prepare a first insulating layer 121 .

[0049] By way of example, and not limitation, a first medium slurry can be applied to the surface of the polished rod segment 111. Preferably, the bolt 110 can be left standing vertically to allow the first medium slurry applied to the surface of the polished rod segment 111 to self-level. By way of example, and not limitation, the self-leveling of the first medium slurry can include leaving the bolt 110 standing vertically at room temperature for 10 minutes.

[0050] The first medium slurry includes but is not limited to a colorless resin slurry with a viscosity of 120 Pa.s, but is not limited thereto. In other examples, the first medium slurry includes but is not limited to a ceramic medium slurry, and the ceramic medium slurry includes but is not limited to a silicon aluminum calcium oxide slurry.

[0051] Step S122: sintering and curing the first dielectric slurry to solidify the first dielectric slurry to form the first insulating layer 121.

[0052] For example but not limited to, the solidification temperature of the first dielectric slurry is 150-200°C (including but not limited to 150°C, 175°C, 200°C), and the solidification time of the first dielectric slurry is 20-40 minutes (for example, 20 minutes, 30 minutes, 40 minutes).

[0053] For example but not limited to, in combination with Figure 1 and Figure 3 Referring to Figure 2 , a sintering furnace 40 is provided, and the bolt 110 provided with the first dielectric slurry is placed in the sintering furnace 40 for sintering and curing, so that the first dielectric slurry is solidified to form the first insulating layer 121. After the first insulating layer 121 is formed, the bolt 110 can be taken out of the sintering furnace 40 and left to cool the first insulating layer 121 to room temperature. Optionally, the sintering furnace 40 can be a muffle furnace.

[0054] Optionally, in combination with Figure 1 and Figure 3 Referring to Figure 2 , step S120 can include step S110 of polishing the surface of the polished rod section 111 of the bolt before step S120.

[0055] In step S110, as shown in Figure 2 , by polishing the surface of the polished rod section 111, the smoothness of the surface of the polished rod section 111 can be improved. The improvement of the smoothness of the surface of the polished rod section 111 is beneficial to improve the bonding strength of the first insulating layer 121 and the polished rod section 111.

[0056] For example but not limited to, referring to Figure 2 , in step S110, a polisher 50 is provided, which includes a support seat 51 for supporting the bolt 110 and a belt polishing mechanism 52, the belt polishing mechanism 52 includes a driving device 53 and an annular polishing belt 54. The annular polishing belt 54 is used to polish the surface of the polished rod section 111, and the driving device 53 is connected with the annular polishing belt 54 to drive the annular polishing belt 54 to move in a ring shape to polish the polished rod section 111. Optionally, the annular polishing belt 54 can include fine-grit sandpaper to polish the polished rod section 111 by the fine-grit sandpaper.

[0057] In comparison Figure 3 Referring to Figure 4 , step S140: arranging the i-th mask plate 60 outside the i-th insulating layer 121, the i-th mask plate 60 is provided with a target pattern hollow hole 63a exposing the i-th insulating layer 121, and the shape of the target pattern hollow hole 63a is adapted to the outer shape of the i-th eddy current coil 122.

[0058] wherein 1≤i≤N, and i is a positive integer.

[0059] contrast Figure 4 in combination Figure 8 reference Figure 5 and Figure 2 At step S160, the i-th eddy current coil 122 is formed by curing the i-th conductive paste in the target patterned aperture 63a of the i-th mask plate 60, and the i-th eddy current coil 122 is fixed to the i-th insulating layer 121. The i-th eddy current coil 122 has a first electrode lead 123 and a second electrode lead 124.

[0060] At step S160, the i-th eddy current coil 122 is formed by curing the i-th conductive paste in the target patterned aperture 63a of the i-th mask plate 60, and the i-th eddy current coil 122 is fixed to the i-th insulating layer 121. The i-th eddy current coil 122 has a first electrode lead 123 and a second electrode lead 124.

[0061] Optionally, step S160 includes step S161 and step S163.

[0062] At step S161, the i-th conductive paste is arranged in the target patterned aperture 63a of the i-th mask plate 60, and the i-th conductive paste is used to prepare the i-th eddy current coil 122.

[0063] The i-th conductive paste includes, but is not limited to, conductive silver paste. For example, the i-th conductive silver paste includes conductive silver paste with a viscosity of 80 Pa.s and a solid content of 70%, but is not limited thereto.

[0064] At step S162, the i-th conductive paste is sintered and cured to form the i-th eddy current coil 122 fixed to the i-th insulating layer 121.

[0065] For example, but not limited to, the curing temperature of the i-th conductive paste is 150°C-200°C (including, but not limited to, 150°C, 175°C, 200°C), and the curing time of the i-th conductive paste is 20 min-40 min (for example, 20 min, 30 min, 40 min), but is not limited thereto.

[0066] For example, but not limited to, the sintering furnace 40 is provided, and the bolt 110 arranged with the i-th conductive paste is placed in the sintering furnace 40 for sintering and curing, so that the i-th conductive paste is cured to form the i-th eddy current coil 122. After the i-th eddy current coil 122 is formed, the bolt 110 can be taken out of the sintering furnace 40, and the i-th eddy current coil 122 is cooled to room temperature by standing.

[0067] At step S163, the conduction of the i-th eddy current coil 122 is checked. If the i-th eddy current coil 122 is conductive, step S180 is entered. If the i-th eddy current coil 122 has an open circuit, step S161 is returned to.

[0068] For example, but not limited to, a multimeter 70 is provided, and the first electrode lead 123 and the second electrode lead 124 of the i-th eddy current coil 122 are respectively electrically connected by using the multimeter 70 to check the conduction of the i-th eddy current coil 122.

[0069] Optionally, in combination with Figure 10 、 Figure 4 Referring to Figure 2 As shown in FIG. 1, the i-th mask plate 60 can include a flexible substrate 62 provided with an adhesive layer 61, and the step S140 can include steps S141-S143, which are as follows.

[0070] Step S141: providing a flexible substrate 62 provided with an adhesive layer 61, the flexible substrate 62 being capable of flexible deformation to switch between a first state and a second state.

[0071] The first state includes the flexible substrate 62 being flatly unfolded, and the second state includes the flexible substrate 62 being flexibly deformed to form a cylindrical structure. Optionally, the material of the flexible substrate 62 includes, but is not limited to, one or more of polyimide film, paper tape, and metal sheet, so that the flexible substrate 62 can be flexibly deformed.

[0072] Step S142: when the flexible substrate 62 is in the first state, a preset patterned hollow hole 63b is provided through the flexible substrate 62 and the adhesive layer 61.

[0073] Wherein, when the flexible substrate 62 is in the second state, the pattern shape of the preset patterned hollow hole 63b is formed into the pattern shape of the target patterned hollow hole 63a.

[0074] For example, but not limited to, when the flexible substrate 62 is in the first state, the flatly unfolded flexible substrate 62 is cut by using a laser cutting device 80 to form the preset patterned hollow hole 63b.

[0075] For example, but not limited to, optionally, considering that a larger laser power is required to form the preset patterned hollow hole 63b by cutting the flexible substrate 62 once, and under a large laser power, the flexible substrate 62 is easy to be burned and curled when cutting, which will cause the edges of the preset patterned hollow hole 63b to be unevenly ablated, to solve this problem, the following improved cutting scheme is proposed.

[0076] The improved cutting scheme: the laser cutting device 80 cuts the flatly unfolded flexible substrate 62 multiple times to form the preset patterned hollow hole 63b in the flexible substrate 62, and the laser cutting device 80 cuts off a thickness of 0.020mm-0.030mm (for example, 0.020mm, 0.025mm, 0.030mm) of the flexible substrate 62 at the corresponding position of the preset patterned hollow hole 63b each time.

[0077] Through the improved cutting scheme, the laser cutting device 80 can cut at a smaller laser power each time, so that the edges of the preset pattern hollow hole 63b formed by the final cutting are more neat and perfect.

[0078] Optionally, in the improved cutting scheme, the number of times of cutting of the laser cutting device 80 is 7-13 times (for example, 7 times, 10 times, 13 times). For example, but not limited to, the laser cutting device 80 cuts the flatly opened flexible substrate 62 for 10 times, and the laser cutting device 80 cuts off the flexible substrate 62 at a thickness of 0.025 mm each time at the position corresponding to the preset pattern hollow hole 63b.

[0079] For example, but not limited to, in the improved cutting scheme, the cutting speed of the laser cutting device 80 is 50 mm / s, the current for the laser cutting device 80 to emit laser is 1 A, the frequency of the current for the laser cutting device 80 to emit laser is 40 kHz, and the Q pulse width of the current for the laser cutting device 80 to emit laser is 10 μs.

[0080] It should be understood that the current for the laser cutting device 80 to emit laser is the current supplied to the laser emitter in the laser cutting device 80 to make the laser emitter emit laser.

[0081] In other alternative embodiments, the preset pattern hollow hole 63b can also be formed by other means in addition to laser cutting, including but not limited to one or more of mechanical cutting, manual cutting, and etching process. Among them, the etching process includes but is not limited to one or more of dry etching and wet etching.

[0082] It should be noted that compared to the etching process for forming the preset pattern hollow hole 63b, which has disadvantages such as complex process, high cost, and time-consuming and laborious, the laser cutting method for forming the preset pattern hollow hole 63b has advantages such as simplified process, reduced cost, and improved efficiency.

[0083] Step S143: By means of flexible deformation, the flexible substrate 62 is switched from the first state to the second state, and the adhesive layer 61 is glued to the outer periphery of the i-th insulating layer 121, so that the i-th insulating layer 121 is located in the cylindrical structure formed by the flexible deformation of the flexible substrate 62.

[0084] Through the above-mentioned manner, since the flexible substrate 62 can be flexibly deformed to switch between the first state and the second state. In this way, in combination with the fact that the adhesive layer 61 is glued to the outer periphery of the i-th insulating layer 121, the i-th insulating layer 121 is located in the cylindrical structure formed by the flexible deformation of the flexible substrate 62. Figure 2 Comparison Figure 5 Reference Figure 6 and Figure 7As shown, the in-situ manufacturing method can further comprise a step S170 of peeling off the i-th mask plate 60 from the i-th insulating layer 121 after the i-th eddy current coil 122 is formed by solidification.

[0085] Specifically, peeling off the i-th mask plate 60 from the periphery of the i-th insulating layer 121 can restore the flexible substrate 62 to the first state for use in the next preparation of another eddy current sensor 120 and formation of the i-th eddy current coil 122. In this way, the mask plate 60 can be repeatedly used to save production costs.

[0086] Optionally, in an example, the 1st mask plate 60 to the Nth mask plate 60 can also be implemented by using the same mask plate 60. In another example, the 1st mask plate 60 to the Nth mask plate 60 can also be implemented by using different mask plates 60.

[0087] In combination Figure 2 By contrast Figure 6 By reference Figure 8 As shown, the step S180 of solidifying the i+1-th insulating layer 121 on the i-th insulating layer 121 covers the i-th eddy current coil 122 and avoids the first electrode lead 123 and the second electrode lead 124 of the i-th eddy current coil 122.

[0088] In order to protect the i-th eddy current coil 122, the i+1-th insulating layer 121 needs to be prepared. Optionally, the step S180 comprises steps S181 to S182.

[0089] The step S181 of arranging the i+1-th dielectric slurry on the i-th insulating layer 121 covers the i-th eddy current coil 122 and avoids the first electrode lead 123 and the second electrode lead 124 of the i-th eddy current coil 122, and the i+1-th dielectric slurry is used to prepare the i+1-th insulating layer 121.

[0090] By way of example but not limitation, the i+1-th dielectric slurry can be brushed on the periphery of the i-th insulating layer 121 and the i-th eddy current coil 122. Preferably, the bolt 110 can be left stationary so that the brushed i+1-th dielectric slurry self-levels. By way of example but not limitation, the self-leveling of the i+1-th dielectric slurry can include vertically leaving the bolt 110 stationary for 8-12 minutes (for example, 8 minutes, 10 minutes, 12 minutes) under room temperature conditions.

[0091] The i+1-th dielectric slurry can include, but is not limited to, a colorless resin slurry with a viscosity of 120 Pa.s, but is not limited thereto. In other examples, the i+1-th dielectric slurry includes, but is not limited to, a ceramic dielectric slurry, which includes, but is not limited to, a silicon aluminum calcium oxide slurry.

[0092] Step S182: sintering and curing the i+1 medium slurry to solidify the i+1 medium slurry to form the i+1 insulating layer 121.

[0093] For example but not limited to, the curing temperature of the i+1 medium slurry is 150-200°C (including but not limited to 150°C, 175°C, 200°C), and the curing time of the i+1 medium slurry is 30 min.

[0094] For example but not limited to, the sintering furnace 40 is provided, and the bolt 110 disposed with the i+1 medium slurry is placed in the sintering furnace 40 for sintering and curing, so that the i+1 medium slurry is solidified to form the i+1 insulating layer 121. After the i+1 insulating layer 121 is formed, the bolt 110 can be taken out of the sintering furnace 40, and the i+1 insulating layer 121 is allowed to cool to room temperature. Optionally, the sintering furnace 40 can be a muffle furnace.

[0095] By the above-mentioned manner, compared with the prior art scheme of pasting the eddy current sensor on the bolt, the technical scheme of the present application has the advantages such as the eddy current sensor can be prepared in situ on the bolt 110, so that the integration of the eddy current sensor 120 and the bolt 110 is improved. Thus, in the technical scheme of the present application, the hole edge damage of the bolt hole 30 can be monitored in real time without disassembling the bolt connection structure composed of the bolt 110 and the corresponding bolt hole 30, the complexity and time cost of monitoring are reduced, and the monitoring efficiency is improved.

[0096] It should be understood that by steps S120-S180, N groups of stacked structures can be formed outside the first insulating layer 121, which are the first group of stacked structures to the Nth group of stacked structures. The i group of stacked structures at least includes the ith eddy current coil 122 and the i+1 insulating layer 121.

[0097] Second embodiment

[0098] The first embodiment of the in-situ preparation method is further limited to form the second embodiment of the in-situ preparation method. The same parts of the second embodiment as the first embodiment will not be repeated, and the further limitation compared with the first embodiment is as follows.

[0099] For example but not limited to, N≥2 Figure 8 The structure corresponding to N=1 is shown in the figure, and the structure corresponding to N≥2 is not shown in the figure, but as long as the number of the eddy current coils 122 is greater than or equal to 2, the structure corresponding to N≥2 can be formed. Figure 8On the basis of, continuing to alternately stack the eddy current coils 122 and the insulating layer 121 can form the structure corresponding to N≥2), N layers of eddy current coils 122 are connected in parallel, and it is defined that 2≤j≤N and j is a positive integer. At this time, the first electrode lead-out end 123 of the j-th eddy current coil 122 is electrically connected to the first electrode lead-out end 123 of the j-1-th eddy current coil 122 through the first region, and the first region is the region of the j-th insulating layer 121 avoiding the first electrode lead-out end 123 of the j-1-th eddy current coil 122; and the second electrode lead-out end 124 of the j-th eddy current coil 122 is electrically connected to the second electrode lead-out end 124 of the j-1-th eddy current coil 122 through the second region, and the second region is the region of the j-th insulating layer 121 avoiding the second electrode lead-out end 124 of the j-1-th eddy current coil 122.

[0100] Third embodiment

[0101] The first embodiment of the in-situ preparation method is further limited to form a third embodiment of the in-situ preparation method. The similarities between the third embodiment and the first embodiment are not repeated here. Compared with the first embodiment, the third embodiment is further limited as follows.

[0102] By way of example and not limitation, N≥2( Figure 8 The structure corresponding to N=1 is shown in the figure. The structure corresponding to N≥2 is not shown in the figure. Figure 8 On the basis of, continuing to alternately stack eddy current coils 122 and insulating layers 121 can form a structure corresponding to when N≥2), N layers of eddy current coils 122 constitute a plurality of coil groups, and each coil group includes at least one layer of eddy current coils 122. Different eddy current coils 122 of the same coil group are connected in parallel, for example, the first electrode lead ends 123 of different eddy current coils 122 of the same coil group are stacked to be electrically connected together, and the second electrode lead ends 124 of different eddy current coils 122 of the same coil group are stacked to be electrically connected together. The eddy current coils 122 of different coil groups are insulated and separated, for example, the first electrode lead ends 123 of the eddy current coils 122 of different coil groups are staggered to be insulated and separated, and the second electrode lead ends 124 of the eddy current coils 122 of different coil groups are staggered to be insulated and separated.

[0103] Fourth embodiment

[0104] The first embodiment of the in-situ preparation method is further limited to form a fourth embodiment of the in-situ preparation method. The fourth embodiment is similar to the first embodiment and is further limited as follows compared to the first embodiment.

[0105] By way of example and not limitation, Figure 8As shown, N=1, by steps S120 to S180, one set of stack structures can be formed outside the first insulating layer 121. The one set of stack structures is the first set of stack structures, and the first set of stack structures at least includes the first eddy current coil 122 and the second insulating layer 121.

[0106] Fifth embodiment

[0107] The first embodiment of the in-situ preparation method is further limited to form the fifth embodiment of the in-situ preparation method. The same parts of the fifth embodiment as the first embodiment will not be repeated, and the further limitation compared with the first embodiment is as follows.

[0108] For example, but not limited to, as Figure 8 As shown, N=2, by steps S120 to S180, two sets of stack structures can be formed outside the first insulating layer 121. The two sets of stack structures are divided into the first set of stack structures and the second set of stack structures. The first set of stack structures at least includes the first eddy current coil 122 and the second insulating layer 121; the second set of stack structures at least includes the second eddy current coil 122 and the third insulating layer 121.

[0109] Sixth embodiment

[0110] The first embodiment of the in-situ preparation method is further limited to form the sixth embodiment of the in-situ preparation method. The same parts of the sixth embodiment as the first embodiment will not be repeated, and the further limitation compared with the first embodiment is that the in-situ preparation method includes step S200 after the Nth insulating layer 121 is solidified to form the N+1th insulating layer.

[0111] Comparison Figure 8 Referring to Figure 9 and Figure 2 Step S200: the first electrode lead-out wire 125 is electrically connected to the first electrode lead-out end 123 of the Nth eddy current coil 122, and the second electrode lead-out wire 126 is electrically connected to the second electrode lead-out end 124 of the Nth eddy current coil 122.

[0112] Optionally, step S200 further includes steps S210 to S240.

[0113] Step S210: providing the first electrode lead-out wire 125, the second electrode lead-out wire 126, the first ceramic sheet 127, the second ceramic sheet 128, and the electrically connecting paste.

[0114] Optionally, the first electrode lead-out wire 125 and the second electrode lead-out wire 126 include but are not limited to nichrome wire, but are not limited thereto. The electrically connecting paste includes but is not limited to conductive silver paste.

[0115] Step S220: placing the first end of the first electrode lead-out wire 125 at the first electrode lead-out end 123 of the Nth eddy current coil 122, and placing the first end of the second electrode lead-out wire 126 at the second electrode lead-out end 124 of the Nth eddy current coil 122.

[0116] Step S230: disposing the electric connection paste on the first electrode lead-out end 123 and the second electrode lead-out end 124 of the Nth eddy current coil 122 respectively, to form a first paste filling part covering the first end of the first electrode lead-out wire 125 of the Nth eddy current coil 122 and a second paste filling part covering the first end of the second electrode lead-out wire 126 of the Nth eddy current coil 122.

[0117] The first paste filling part is used to prepare the first solidified connection part 129, and the second paste filling part is used to prepare the second solidified connection part 130.

[0118] Step S240: covering the first ceramic sheet 127 on the first paste filling part, and covering the second ceramic sheet 128 on the second paste filling part, and sintering the first paste filling part and the second paste filling part in the state that the first ceramic sheet 127 and the second ceramic sheet 128 are clamped on the bolt 110, so that the first paste filling part is solidified to form the first solidified connection part 129, and the second paste filling part is solidified to form the second solidified connection part 130.

[0119] The first solidified connection part 129 formed in step S240 solidly connects the first electrode lead-out end 123 of the Nth eddy current coil 122 and the first end of the first electrode lead-out wire 125, so that the connection strength of the first electrode lead-out end 123 of the Nth eddy current coil 122 and the first electrode lead-out wire 125 can be improved. The second solidified connection part 130 formed in step S240 solidly connects the second electrode lead-out end 124 of the Nth eddy current coil 122 and the first end of the second electrode lead-out wire 126, so that the connection strength of the second electrode lead-out end 124 of the Nth eddy current coil 122 and the first end of the second electrode lead-out wire 126 can be improved.

[0120] Seventh Embodiment

[0121] Optionally, the sixth embodiment of the in-situ preparation method is further limited to form the seventh embodiment of the in-situ preparation method. In combination with the above description of the first embodiment, Figure 5- Figure 7 Referring to FIG. 7, Figure 2 The seventh embodiment is the same as the first embodiment, and details are not repeated. Compared with the sixth embodiment, the further limitation of the seventh embodiment is that the ith eddy current coil 122 includes a Huizi-shaped coil 122a distributed on the cylindrical surface of the ith insulating layer 121, and the details are as follows.

[0122] As shown in FIG. 7, Figure 2As shown, in step S142 , the pattern shape of the preset pattern hollow holes 63 b includes a U-shaped pattern distributed on the plane where the flexible substrate 62 is located.

[0123] like Figure 2 As shown, in step S143, the flexible substrate 62 is switched from the first state to the second state, which includes bringing two opposite sides of the flexible substrate 62 provided with the preset pattern hollow holes 63b and unfolded in a plane closer together along the length direction, so that the flexible substrate 62 is flexibly bent into a cylindrical structure.

[0124] When the flexible substrate 62 is flexibly bent into the cylindrical structure, the plane where the flexible substrate 62 was originally located in the first state is bent to form the cylindrical surface where the flexible substrate 62 is flexibly bent into the cylindrical structure in the second state.

[0125] Combine Figure 5- Figure 7 See Figure 2 As shown, through the above method, the i-th eddy current coil 122 formed in the subsequent step S160 can be a U-shaped coil 122a distributed on the cylindrical surface of the outer periphery of the i-th insulating layer 121. The U-shaped coil 122a includes multiple turns of coil distributed on the cylindrical surface of the outer periphery of the i-th insulating layer 121 and extending from the inside to the outside. The first electrode lead end 123 of the i-th eddy current coil 122 can be located in the middle of the polished rod segment 111 and on the innermost coil, and the second electrode lead end 124 of the i-th eddy current coil 122 can be located at the top of the polished rod segment 111 and on the outermost coil.

[0126] Optionally, N may be equal to 1, and in step S141 , in the first state, the length of the flexible substrate 62 is 37.6 mm, the width of the flexible substrate 62 is 30 mm, and the thickness of the flexible substrate 62 is 0.25 mm.

[0127] Optionally, the coil in the U-shaped coil 122a is rectangular. Optionally, the line width and line spacing of the U-shaped coil 122a are both ≤ 1 mm, and the number of turns of the U-shaped coil 122a is at least 8.

[0128] Eighth embodiment

[0129] Furthermore, the sixth embodiment of the above in-situ preparation method is further limited to form the eighth embodiment of the in-situ preparation method. Figure 6 and Figure 7 For reference Figure 11 and Figure 12 The eighth embodiment is similar to the sixth embodiment and is not described in detail. Compared with the sixth embodiment, the eighth embodiment is further limited in that the i-th eddy current coil 122 includes a spiral coil 122b distributed on the cylindrical surface of the outer periphery of the i-th insulating layer 121, as follows.

[0130] likeFigure 13 As shown, in step S142 , the pattern shape of the preset pattern hollow holes 63 b includes a stripe pattern distributed on the plane where the flexible substrate 62 is located and extending along a straight line direction.

[0131] like Figure 16 As shown, in step S143 , switching the flexible substrate 62 from the first state to the second state includes: spirally winding the flexible substrate 62 along the cylindrical surface of the outer periphery of the i-th insulating layer 121 and along the axial direction of the polished rod segment 111 .

[0132] By way of example and not limitation, Figure 13 、 Figure 14 and Figure 15 See Figure 16 As shown, step S143 includes step S1431 and step S1432:

[0133] Step S1431 : gluing the adhesive layer 61 at one end of the stripe pattern of the preset pattern hollow hole 63 b to the periphery of the top of the i-th insulating layer 121 , with the extending direction of the stripe pattern tilted relative to the axial direction of the polished rod segment 111 .

[0134] Optionally, the acute angle formed by the extending direction of the stripe pattern relative to the axial direction of the polished rod segment 111 is a first angle β, and the first angle β is 30 degrees to 80 degrees (for example, 30 degrees, 50 degrees, or 80 degrees).

[0135] Step S1432: The bolt 110 is rotated to drive the flexible substrate 62 to spirally rotate along the cylindrical surface of the outer periphery of the i-th insulating layer 121, so that the adhesive layer 61 in other areas of the flexible substrate 62 is gradually bonded to the outer periphery of the i-th insulating layer 121, causing the flexible substrate 62 to flexibly deform and enclose into a cylindrical structure.

[0136] Through the above method, the i-th eddy current coil 122 formed in the subsequent step S160 can be a spiral coil 122b distributed on the cylindrical surface of the outer periphery of the i-th insulating layer 121. The spiral coil 122b includes multiple turns of coil distributed on the cylindrical surface of the outer periphery of the i-th insulating layer 121 and distributed along the axial direction of the polished rod segment 111. The first electrode lead end 123 of the i-th eddy current coil 122 can be located at the top end of the polished rod segment 111, and the second electrode lead end 124 of the i-th eddy current coil 122 can be located at the bottom end of the polished rod segment 111.

[0137] Optionally, N may be equal to 1, the first angle β may be 80 degrees, and in step S141 , in the first state, the length of the flexible substrate 62 is 380.16 mm, the width of the flexible substrate 62 is 1 mm, and the thickness of the flexible substrate 62 is 0.25 mm.

[0138] Optionally, the helical coil 122b has a wire width and a wire spacing both less than or equal to 1 mm, and the helical coil 122b has at least 10 turns.

[0139] The bolt connection 100 provided by the application comprises a bolt 110 and an eddy current sensor 120. The bolt 110 is the bolt 110 in the in-situ preparation method described above, and the eddy current sensor 120 is the eddy current sensor 120 prepared by the in-situ preparation method described above, which will not be described here.

[0140] Referring to FIGS. 1-3, Figure 17 and Figure 18 The eddy current sensor monitoring system 10 provided by the application comprises a bolt connection 100, an excitation source 200, and an electrical signal analyzer 300.

[0141] The bolt connection 100 is the bolt connection 100 described above, which will not be described here. The bolt connection 100 is arranged at the bolt hole 30 of the medium body 20 in different layers to connect the medium bodies 20 in different layers. The excitation source 200 is electrically connected to at least part of the first electrode lead-out end 123 and the second electrode lead-out end 124 of each of the N layers of the eddy current coil 122 of the bolt connection 100. The electrical signal analyzer 300 is electrically connected to at least part of the first electrode lead-out end 123 and the second electrode lead-out end 124 of each of the N layers of the eddy current coil 122 of the bolt connection 100.

[0142] The excitation source 200 is configured to apply alternating current to at least part of the eddy current coils 122 to cause the corresponding eddy current coils 122 to generate corresponding excitation magnetic fields. The composite material layer around the periphery of the bolt hole 30 can generate an induced magnetic field corresponding to its damage state under the action of the excitation magnetic field. At least part of the eddy current coils 122 has a corresponding induced electrical signal based on the action of the induced magnetic field. The electrical signal analyzer 300 is configured to monitor the induced electrical signal of at least part of the eddy current coils 122 based on the action of the induced magnetic field.

[0143] In this way, the electrical signal analyzer 300 can quantitatively evaluate the health status of the medium body 20 in different layers by analyzing the induced electrical signal. The in-situ real-time monitoring of the medium body 20 in different layers can be realized without disassembling the bolt connection structure composed of the bolt 110 of the bolt connection 100 and the corresponding bolt hole 30, thereby realizing real-time monitoring of the hole edge damage of the bolt hole 30, reducing the complexity and time cost of monitoring, and improving the monitoring efficiency. The technical solution of the application has the advantages of simple and convenient process, low time cost, and multiple reuse compared with the existing monitoring method.

[0144] For example, but not limited to, the excitation source 200 applies alternating current to at least part of the eddy current coils 122 with a voltage frequency of 1 MHz and an amplitude of 2 V, but is not limited thereto.

[0145] Optionally, the induced electrical signal can be one or more of a corresponding impedance, a reactance, a voltage, and a current that the eddy current coil 122 has based on the effect of the induced magnetic field. By way of example and not limitation, the induced electrical signal can be an apparent resistance, and the electrical signal analyzer 300 can be an impedance analyzer.

[0146] By way of example and not limitation, the N-layer eddy current coil 122 is used both to generate the excitation magnetic field and to receive the induced magnetic field. That is, the excitation source 200 is used to apply an alternating current to the N-layer eddy current coil 122, and the electrical signal analyzer 300 is used to monitor the induced electrical signal that the N-layer eddy current coil 122 has based on the effect of the induced magnetic field.

[0147] Optionally, the excitation source 200 and the electrical signal analyzer 300 can be integrated into the same device to form an integrated device 90. In this way, the eddy current sensor monitoring system 10 can be miniaturized. By way of example and not limitation, the integrated device 90 includes, but is not limited to, a precision impedance analyzer.

[0148] The above merely provides an implementation of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process conversion using the content of the present application specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An in-situ preparation method of an eddy current sensor, characterized in that: The in-situ preparation method is used to in-situ prepare the eddy current sensor on the periphery of the bolt; the eddy current sensor includes N layers of eddy current coils and N+1 layers of insulation layers, where N is a positive integer; the bolt includes a screw section and a polished rod section, and the in-situ preparation method includes: Step S120: solidifying the outer periphery of the polished rod segment to form a first insulating layer covering the polished rod segment; Step S140: arranging an i-th mask plate on the periphery of the i-th insulating layer, wherein the i-th mask plate is provided with a target pattern hollow hole, and the pattern shape of the target pattern hollow hole is adapted to the shape of the i-th eddy current coil; Step S160: solidifying the i-th eddy current coil fixed to the i-th insulating layer in the target pattern hollow hole, wherein the i-th eddy current coil has a first electrode lead-out terminal and a second electrode lead-out terminal, where 1≤i≤N and i is a positive integer; Step S180 : solidifying to form an (i+1)th insulating layer on the (i)th insulating layer, wherein the (i+1)th insulating layer covers the (i)th eddy current coil and avoids the first electrode lead-out end and the second electrode lead-out end of the (i)th eddy current coil.

2. The in-situ preparation method of the eddy current sensor according to claim 1, characterized in that: N≥1。 3. The in-situ preparation method of the eddy current sensor according to claim 1, characterized in that: N≥2。 4. The in-situ preparation method of the eddy current sensor according to claim 1, characterized in that: After solidifying the Nth insulating layer to form the N+1th insulating layer, the method further includes: The first electrode lead-out end of the Nth eddy current coil is electrically connected to a first electrode lead-out wire, and the second electrode lead-out end of the Nth eddy current coil is electrically connected to a second electrode lead-out wire.

5. The in-situ preparation method of the eddy current sensor according to claim 1, characterized in that: The i-th eddy current coil includes a U-shaped coil distributed on the cylindrical surface of the outer periphery of the i-th insulating layer or a spiral coil distributed on the cylindrical surface of the outer periphery of the i-th insulating layer.

6. The in-situ preparation method of an eddy current sensor according to claim 1, characterized in that: The step S160 includes: Arranging an i-th conductive paste in the target pattern hollow hole of the i-th mask, wherein the i-th conductive paste is used to prepare the i-th eddy current coil; The i-th conductive paste is sintered and cured, so that the i-th conductive paste is cured to form the i-th eddy current coil fixed to the i-th insulating layer.

7. The in-situ preparation method of an eddy current sensor according to claim 1, characterized in that: The step S120 includes: Arranging a first dielectric slurry on the outer periphery of the polished rod segment, wherein the first dielectric slurry is used to prepare a first insulating layer; sintering and curing the first dielectric slurry to form the first insulating layer; The step S180 includes: Arranging an (i+1)th dielectric slurry on the (i)th insulating layer, the (i+1)th dielectric slurry covering the (i)th eddy current coil and avoiding the first electrode lead-out end and the second electrode lead-out end of the (i)th eddy current coil, the (i+1)th dielectric slurry being used to prepare the (i+1)th insulating layer; The i+1th dielectric slurry is sintered and solidified to form the i+1th insulating layer.

8. The in-situ preparation method of an eddy current sensor according to claim 1, characterized in that: The i-th mask includes a flexible substrate provided with a backing adhesive layer, and the step S140 includes: A flexible substrate provided with a backing adhesive layer is provided, wherein the flexible substrate is capable of flexibly deforming to switch between a first state and a second state; the first state includes the flexible substrate being flatly unfolded, and the second state includes the flexible substrate being flexibly deformed to form a cylindrical structure; When the flexible substrate is in the first state, a preset pattern hollow hole is provided through the flexible substrate and the adhesive layer; when the flexible substrate is in the second state, the pattern shape of the preset pattern hollow hole is formed to be the pattern shape of the target pattern hollow hole; The flexible substrate is switched from the first state to the second state by flexible deformation, and the back adhesive layer is bonded to the outer periphery of the i-th insulating layer so that the i-th insulating layer is located within the cylindrical structure enclosed by the flexible deformation of the flexible substrate.

9. The in-situ preparation method of an eddy current sensor according to claim 1, characterized in that: Between step S160 and step S180 , the method further includes step S170 : after the i-th eddy current coil is solidified and formed, peeling the i-th mask from the i-th insulating layer.

10. A bolt connector, characterized in that: The bolt connection includes a bolt and an eddy current sensor; the eddy current sensor includes N layers of eddy current coils and N+1 layers of insulation layers; the bolt includes a screw segment and a polished rod segment, and the eddy current sensor is prepared in situ on the periphery of the bolt using the in-situ preparation method of the eddy current sensor described in any one of claims 1-9.

11. An eddy current sensing monitoring system, comprising: A bolt connector, wherein the bolt connector is the bolt connector according to claim 10, and the bolt connector is used to be arranged at bolt holes of dielectric bodies of different layers to connect dielectric bodies of different layers; an excitation source electrically connected to the first electrode lead-out end and the second electrode lead-out end of at least some layers of the N-layer eddy current coil of the bolt connector; and an electrical signal analyzer, electrically connected to the first electrode lead-out end and the second electrode lead-out end of at least some layers of the N-layer eddy current coil of the bolt connector, respectively; The excitation source is used to apply alternating current to at least some of the layers of the eddy current coils, so that the corresponding eddy current coils generate corresponding excitation magnetic fields; the composite material layer around the bolt hole can be affected by the excitation magnetic field to generate an induced magnetic field corresponding to its own damage state; and the eddy current coils of at least some of the layers generate corresponding induced electrical signals based on the induced magnetic field. The electrical signal analyzer is used to monitor the induced electrical signals of the eddy current coils of at least a portion of the layers due to the action of the induced magnetic field.

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