3D printing liquid metal filled orthogonal eddy current probe and preparation method thereof

Abstract

The invention belongs to the technical field of nondestructive testing, and particularly relates to a 3D printing liquid metal filled orthogonal eddy current probe and a preparation method thereof, the 3D printing liquid metal filled orthogonal eddy current probe comprises a 3D printing formed probe main body, an excitation coil channel and a detection coil channel are formed in the probe main body, and the excitation coil channel and the detection coil channel are orthogonally arranged; at least two pairs of through holes communicated with the excitation coil channel and the detection coil channel are formed in the surface of the probe main body; the excitation coil channel and the detection coil channel are filled with conductive liquid metal to form an excitation coil and a receiving coil respectively; the through hole is provided with a plugging member and a conductive member used for wiring conduction of the excitation coil and the receiving coil. The coil channel is formed through 3D printing to realize complete orthogonality of key wires in the coil, so that a real object of the orthogonal eddy current probe is closer to a theoretical design, measurement errors caused by probe manufacturing precision in actual measurement of the probe are reduced, and the detection precision of the orthogonal eddy current probe containing the orthogonal coil can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nondestructive testing, and in particular relates to a 3D printed liquid metal filled orthogonal eddy current probe and a preparation method thereof. Background Art

[0002] Eddy current testing is one of the five conventional non-destructive testing technologies. It has the advantages of non-contact, simple equipment, easy operation, single-sided testing, simple surface cleaning of workpieces, and easy automation. It has been widely used in aerospace, petrochemical, nuclear energy, military and other fields. Eddy current sensor design is an important research direction of eddy current testing technology.

[0003] Chinese patent CN 213580777 U discloses a cross pulse eddy current detection probe, which mainly includes two mutually orthogonal rectangular excitation coils and a cylindrical detection coil. This probe has an automatic zeroing function and can identify surface and subsurface crack defects that may extend in all directions.

[0004] Chinese patent CN 117665097 A discloses an orthogonal axial eddy current probe, in which the excitation coil and the detection coil are placed orthogonally to each other; the detection coil is a rectangular coil, placed perpendicular to the surface of the metal workpiece to be tested; the excitation coil is a runway-shaped coil, placed axially at the center of the detection coil.

[0005] Chinese patent CN 112525986 A discloses a tic-tac-toe planar eddy current sensor, which mainly includes excitation line segments and rectangular detection coils distributed in a tic-tac-toe pattern, and the shape of the detection coil coincides with the closed quadrilateral area defined by the excitation line segments. Sinusoidal excitation signals with the same frequency and amplitude and a phase difference of 90° are respectively passed through the two groups of excitation line segments, and a uniform rotating field can be induced in the test piece. The eddy current sensor can effectively detect cracks at any angle.

[0006] Patent CN 213580777 U and Patent CN 117665097 A both use orthogonal coils, but existing eddy current probes are often made by hand or machine winding, and it is impossible to make the two coils completely orthogonal, which will affect the detection accuracy of the eddy current probe in principle. Patent CN 112525986 A uses PCB boards to make completely orthogonal eddy current probes, but PCB boards are not suitable for making complex three-dimensional coils, and the number of turns of the PCB coil will be severely limited by the number of layers of the PCB board, affecting the detection capability of the probe. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a 3D printed liquid metal filled orthogonal eddy current probe and a preparation method thereof.

[0008] The technical solution adopted by the present invention is as follows: a 3D printed liquid metal filled orthogonal eddy current probe, comprising a probe body formed by 3D printing, wherein an excitation coil channel and a detection coil channel are formed inside the probe body, and the excitation coil channel and the detection coil channel are arranged orthogonally to each other; at least two pairs of through holes connected to the excitation coil channel and the detection coil channel are provided on the surface of the probe body;

[0009] The excitation coil channel and the detection coil channel are filled with conductive liquid metal, forming an excitation coil and a receiving coil respectively; a blocking piece is provided at the through hole and a conductive piece is provided for connecting and conducting the excitation coil and the receiving coil.

[0010] Preferably, the conductive liquid metal is GaInSn having conductivity.

[0011] Preferably, conductive particles are added into the conductive liquid metal, and the conductivity of the conductive particles is greater than the conductivity of the liquid metal.

[0012] The method for preparing the 3D printed liquid metal filled orthogonal eddy current probe as described above comprises the following steps:

[0013] Step 1: Form a probe body having an excitation coil channel and a detection coil channel therein by 3D printing;

[0014] Step 2: Filling the exciting coil channel and the detecting coil channel with conductive liquid metal through the through holes on the surface of the probe body;

[0015] Step 3: Set up a blocking member and a conductive member, and block the through hole with the blocking member to keep the liquid metal in the excitation coil channel and the detection coil channel.

[0016] The beneficial effects of the present invention are as follows: the present invention forms a coil channel through 3D printing to achieve complete orthogonality of the key wires in the coil, so that the actual orthogonal eddy current probe is closer to the theoretical design, thereby reducing the measurement error caused by the probe manufacturing accuracy in actual measurement, and can effectively improve the detection accuracy of the orthogonal eddy current probe containing an orthogonal coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0018] Figure 1 A flow chart for preparing an orthogonal eddy current probe for the present invention;

[0019] Figure 2 This is a schematic structural diagram of a probe body according to Embodiment 1 of the present invention;

[0020] Figure 3 This is a schematic diagram of the coordination structure of the excitation coil and the receiving coil according to Embodiment 1 of the present invention;

[0021] Figure 4 This is a schematic structural diagram of a probe body according to Embodiment 2 of the present invention;

[0022] Figure 5 This is a schematic diagram of the coordination structure of the excitation coil and the receiving coil according to Embodiment 2 of the present invention;

[0023] Figure 6 This is a schematic structural diagram of a probe body according to Embodiment 3 of the present invention;

[0024] Figure 7 This is a schematic diagram of the coordination structure of the excitation coil and the receiving coil according to Embodiment 3 of the present invention;

[0025] In the figure, the probe body-1, the excitation coil channel-101, the detection coil channel-102, the through hole-103, the excitation coil-2, and the receiving coil-3. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] The present invention provides a 3D printed liquid metal filled orthogonal eddy current probe, comprising a probe body 1 formed by 3D printing, wherein an excitation coil channel 101 and a detection coil channel 102 are formed inside the probe body 1, and the excitation coil channel 101 and the detection coil channel 102 are arranged orthogonally to each other; at least two pairs of through holes 103 connected to the excitation coil channel 101 and the detection coil channel 102 are provided on the surface of the probe body 1;

[0028] The excitation coil channel 101 and the detection coil channel 102 are filled with conductive liquid metal, forming the excitation coil 2 and the receiving coil 3 respectively; the through hole 103 is provided with a blocking piece and a conductive piece for connecting and conducting the excitation coil 2 and the receiving coil 3 .

[0029] Each coil needs to be provided with a pair of through holes 103 to form the two ends of the coil.

[0030] Liquid metal is in liquid state at room temperature and has fluidity. It can be well filled into the excitation coil channel 101 and the detection coil channel 102 inside the probe body 1 at room temperature. The excitation coil 2 and the receiving coil 3 can be formed by using conductive liquid metal. In some embodiments of the present invention, the conductive liquid metal is GaInSn. The conductivity of liquid metal GaInSn at room temperature is one order of magnitude smaller than that of metallic copper. In order to make the coil have better conductivity, in other embodiments of the present invention, conductive particles with higher conductivity, such as silver particles, are added to the liquid metal GaInSn to improve the overall conductivity of the excitation coil 2 and the receiving coil 3, making it as close as possible to metallic copper or even surpassing metallic copper.

[0031] like Figure 1 As shown, the present invention also provides a method for preparing the 3D printed liquid metal filled orthogonal eddy current probe as described above, comprising the following steps:

[0032] Step 1: Form a probe body 1 having an excitation coil channel 101 and a detection coil channel 102 therein by 3D printing;

[0033] Step 2: Fill the excitation coil channel 101 and the detection coil channel 102 with conductive liquid metal through the through hole 103 on the surface of the probe body 1 to form the excitation coil 2 and the receiving coil 3;

[0034] Step 3: Setting a blocking member and a conductive member, and blocking the through hole 103 by the blocking member to keep the liquid metal in the excitation coil channel 101 and the detection coil channel 102 .

[0035] In step 1, photocuring 3D printing is used to print the probe body 1 having the excitation coil channel 101 and the detection coil channel 102 inside based on the photopolymerization reaction of liquid photosensitive resin. Photocuring 3D printing can print very fine structures, making the actual orthogonal eddy current probe closer to the theoretical design. After printing is completed, the support material in the channel is removed by flushing the residual liquid in the flow channel with an air pump.

[0036] In step 2, liquid metal GaInSn or GaInSn with silver particles added is filled into the printed coil channel using a negative pressure method until the liquid metal fills the coil channel.

[0037] In some embodiments of the present invention, the sealing member and the conductive member are integrated. In step three, the sealing member is directly sealed and solidified by a conductive hot melt adhesive (a hot melt adhesive with conductive filler added) to form a sealing member that prevents the liquid metal from flowing out and a conductive member that constitutes the wiring structure of the excitation coil 2 and the receiving coil 3.

[0038] In other embodiments of the present invention, the blocking member and the conductive member are separate. The blocking member is formed by sealing and curing the hot melt adhesive to prevent the liquid metal from flowing out. At the same time, before the curing is completed, the conductive lead is inserted and passed through the hot melt adhesive and extended into the liquid metal. The conductive lead serves as a conductive member of the wiring structure of the excitation coil 2 and the receiving coil 3.

[0039] When the orthogonal eddy current probe filled with 3D printed liquid metal prepared by the present invention is used for non-destructive testing, the primary magnetic field generated by the excitation coil 2 of the orthogonal eddy current probe is parallel to the receiving coil 3, and the voltage signal induced on the receiving coil 3 is zero. When the material to be tested is defect-free, the secondary magnetic field generated by the eddy current in the material to be tested is also parallel to the receiving coil 3, and the voltage signal induced on the receiving coil 3 is still zero. If there are defects in the material to be tested, the defects will disturb the eddy current, causing the secondary magnetic field generated by the eddy current to change. At this time, the voltage signal of the receiving coil 3 changes, so that it is judged whether there is a signal in the material to be tested based on the voltage signal of the receiving coil 3, and the defect information is analyzed. Therefore, the orthogonality of the two coils will affect the detection effect of the probe in principle. The present invention makes the orthogonality of the two coils more accurate and close to the theory, so the detection effect is also more accurate.

[0040] The following are some specific examples prepared by the present invention.

[0041] Embodiment 1:

[0042] A structure of the orthogonal eddy current probe of the present invention is as follows Figure 2 , Figure 3 As shown, Figure 2 The schematic diagram of the structure of the probe body 1 formed by 3D printing is shown in FIG. 1 , in which an excitation coil channel 101 and a detection coil channel 102 are formed. By injecting liquid metal, a liquid metal can be formed inside. Figure 3 The coil symmetry axis of the excitation coil 2 is along the y direction, and the coil symmetry axis of the receiving coil 3 is along the x direction. The receiving coil 3 is wound around the excitation coil and is orthogonal to the excitation coil.

[0043] Embodiment 2:

[0044] A structure of the orthogonal eddy current probe of the present invention is as follows Figure 4 , Figure 5 As shown, Figure 4 The schematic diagram of the structure of the probe body 1 formed by 3D printing is shown in FIG. 1 , in which an excitation coil channel 101 and a detection coil channel 102 are formed. By injecting liquid metal, a liquid metal can be formed inside. Figure 5 The coil symmetry axis of the excitation coil 2 is along the y direction, and the coil symmetry axis of the receiving coil 3 is along the x direction. The receiving coil 3 is wound on the bottom side of the excitation coil and is orthogonal to the excitation coil 2.

[0045] Embodiment 3:

[0046] A structure of the orthogonal eddy current probe of the present invention is as follows Figure 6 , Figure 7 As shown, Figure 6 It is a schematic diagram of the structure of the probe body 1 formed by 3D printing, in which an excitation coil channel 101 and a detection coil channel 102 are formed, forming an excitation coil 2 and a receiving coil 3, wherein the large circular coil is the excitation coil 2, and the small circular coil is the receiving coil 3, and the receiving coil 3 is wound on the excitation coil and is orthogonal to the excitation coil 2. There are multiple receiving coils 3, and a group of through holes 103 are provided on the surface of the probe body 1 corresponding to the excitation coil 2 and at both ends of each receiving coil 3 for injecting liquid metal and as a wiring part, and the through holes 103 can be set on the upper end face, the circumferential end face or the lower end face of the probe body 1.

[0047] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0048] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A 3D printed liquid metal filled orthogonal eddy current probe, characterized in that: The probe body (1) comprises a probe body (1) formed by 3D printing, wherein an excitation coil channel (101) and a detection coil channel (102) are formed inside the probe body (1), and the excitation coil channel (101) and the detection coil channel (102) are arranged orthogonally to each other; and at least two pairs of through holes (103) communicating with the excitation coil channel (101) and the detection coil channel (102) are arranged on the surface of the probe body (1); The excitation coil channel (101) and the detection coil channel (102) are filled with conductive liquid metal, respectively constituting an excitation coil (2) and a receiving coil (3); a blocking member is provided at the through hole (103) and a conductive member is provided for connecting and conducting the excitation coil (2) and the receiving coil (3).

2. The 3D printed liquid metal filled orthogonal eddy current probe according to claim 1, characterized in that: The conductive liquid metal is GaInSn with conductivity.

3. The 3D printed liquid metal filled orthogonal eddy current probe according to claim 2, characterized in that: Conductive particles are added into the conductive liquid metal, and the conductivity of the conductive particles is greater than the conductivity of the liquid metal.

4. The method for preparing a 3D printed liquid metal filled orthogonal eddy current probe according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: forming a probe body (1) having an excitation coil channel (101) and a detection coil channel (102) therein by 3D printing; Step 2: filling the excitation coil channel (101) and the detection coil channel (102) with conductive liquid metal through the through hole (103) on the surface of the probe body (1); Step 3: Setting a blocking member and a conductive member, and blocking the through hole (103) by the blocking member to keep the liquid metal in the excitation coil channel (101) and the detection coil channel (102).

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