CN108982654B - A right-angle meandering fancy eddy current sensor and its coil winding method - Google Patents

Abstract

The invention relates to a right-angle type meander type eddy current sensor and a winding method of a coil thereof, which comprises a printed circuit board and a coil group printed on the printed circuit board; the coil group comprises an excitation coil wound into a right-angle shape, the right-angle excitation coil comprises a transverse edge and a vertical edge which form a right angle, and a folding edge which forms a certain angle with two edges of the right angle, the transverse edge, the vertical edge and the folding edge respectively comprise a meandering fold line which is vertically arranged with the edge, the meandering fold line comprises at least one meandering unit, and a plurality of meandering units are connected in series; the detection coil is wound in the winding line gap on each side, and each group of detection coils is wound in at least one winding unit. The invention can conveniently detect the stress and strain in various metal components in a plane stress state in a non-contact manner under the condition of only using one sensor.

Description

A right-angle meandering fancy eddy current sensor and its coil winding method

technical field

The invention belongs to the technical field of non-destructive testing, and relates to a right-angle meandering fancy eddy current sensor used for detecting component stresses and linear strains in three different directions in a metal structure under a plane stress state.

Background technique

The vast majority of mechanical structures are made of metal materials, and the effective detection of the stress state of these metal structures is of great significance for understanding their service status and evaluating their remaining life.

At present, the commonly used methods for detecting the stress state in metal structures include strain gauge method, X-ray method, ultrasonic method and magnetic measurement method. Among these methods, the strain gage method requires contact measurement; the X-ray method is expensive and has radiation hazards and is only suitable for laboratory testing; the ultrasonic method requires couplants; and the magnetic method is only suitable for the detection of ferromagnetic materials.

The eddy current testing method has the advantages of simple operation, low cost, no coupling agent and non-contact measurement. It has been widely used in the detection of the stress of metal structures. In the elastic range of the material, the strain of the metal structure has a linear relationship with the stress, so the eddy current testing method can also be used to detect the strain of the metal structure.

Existing eddy current stress detection research is limited to the detection of unidirectional stress and strain, lack of eddy current sensors that can detect the direction of stress and strain, and lack of eddy current sensors that can detect stress and strain in metal structures under plane stress state when the principal stress direction is unknown. Eddy current sensor.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an eddy current sensor which can detect the stress and strain in the metal structure under the plane stress state.

The present invention adopts following technical scheme:

A right-angle meandering fancy eddy current sensor includes a printed circuit board and a coil group printed on the printed circuit board;

The coil set includes:

A right-angle excitation coil is wound, and the right-angle excitation coil includes horizontal and vertical sides that form a right angle, and a folded edge that forms a certain angle with the two sides of the right angle. Each includes a serpentine fold line perpendicular to the edge, the serpentine fold line includes at least one serpentine unit, and a plurality of serpentine units are connected in series;

Also included is a set of detection coils wound within the serpentine zigzag gap on each side, each set of detection coils wound within at least one serpentine unit.

Further, each group of detection coils includes at least one independent detection coil, which is wound in the same side gap of the series meandering units.

Further, each set of detection coils includes at least two independent detection coils, wherein one detection coil is wound in the gap on one side of the meandering line, and the other detection coil is wound in the gap on the other side of the meandering line.

Further, the distance between the detection coil wound in the serpentine unit on each side and the wire forming the serpentine unit satisfies: under the condition of electrification, the detection coil can detect the eddy current change excited by the wire forming the serpentine unit information.

Further, there is no less than one independent detection coil wound on the same side of the meandering fold line, the detection coils in the meandering unit gap are all non-closed rectangles, and at least two independent detection coils wound on the same side of the same meandering fold line. The coils can be connected in series or separately to external detection devices.

Further, excitation coils with corresponding positions and the same shape can be arranged on multiple layers of the printed circuit board, and the excitation coils on different layers are connected in series;

Detection coils with corresponding positions and the same shape can be arranged on multiple layers of the printed circuit board, and the detection coils on different layers are connected in series;

The excitation coil and the detection coil are located on the same layer or on different layers.

Further, the folded edge bisects the right angle into two 45-degree angles.

The invention also provides a coil winding method of a right-angle meandering fancy eddy current sensor, including a method for winding an excitation coil and a method for winding a detection coil; the sides a and b of the right-angle type are set as right-angle sides, and the side c is hemming,

The method for winding the excitation coil includes:

Walk along the edge a from the starting point S1, after walking the distance da1, wind the zigzag line, after the winding of the zigzag line is completed, continue to walk the distance da2, bend 90° to the side b, continue to trace the distance db1, and wind After winding the winding line, continue to walk the distance db2, and then bend a certain angle within the right angle range formed by side a and side b, continue to route the distance db3, and then go to the two sides of the right angle. Bend the side d at a certain angle, continue to route the distance dd1, and wind the zigzag line. After the winding of the zigzag line is completed, continue to route the distance dd2 to reach the end point S2;

The detection coil winding method includes:

On each side of the excitation coil, a detection coil is wound in the gap of the meandering unit on one side of the meandering fold line from the starting position, or a detection coil is respectively wound in the gap on both sides of the meandering unit; the detection coil is a serpentine fold line with a certain distance from the serpentine fold line of the excitation coil.

Further, the winding method of the meandering line is:

S1: Line distance D1 along the direction perpendicular to the edge of the meandering fold line, where D1 is the unit length of the meandering unit;

S2: From the current position, after bending 90° in the direction away from the starting point S1, run the line D2 again along the bending direction, and this D2 is the width I of the meandering unit;

S3: From the current position, bend 90 degrees to the direction of the triangle side where the meandering line is located, and route line D1 along the bent direction;

S4: From the current position, bend 90 degrees away from the starting direction S1, and route the line D3 along the bent direction to complete the routing of a meandering unit; this D3 is the width II of the meandering unit;

S5: Multiple meander units are connected in series to form meander lines.

Further, the width I and the width II of the same meandering unit of the excitation coil are the same or different;

When a detection coil is wound in the gap of at least one serpentine unit of the excitation coil, the width I and width II of the same serpentine unit of the detection coil are different in length.

Beneficial effects of the present invention:

(1) The present invention provides an eddy current sensor that can detect the partial stress and linear strain in three different directions in a metal structure under a plane stress state without knowing the principal stress direction, breaking through the existing eddy current sensor that can only detect Unidirectional stress and strain defects. After using the eddy current sensor provided by the present invention to detect the partial stress and linear strain in three different directions in the metal structure, the magnitude and direction of the principal stress and principal strain in the metal structure can be determined according to the method of experimental stress analysis.

(2) Using this kind of sensor, the stress and strain in various metal components under the plane stress state can be detected conveniently and non-contact when only one sensor is used. In the existing research, in order to detect the component stress and linear strain in three directions, more than three eddy current sensors need to be used, and it is difficult to ensure the consistency of lift-off between multiple sensors and the measured structure. Therefore, the present invention is beneficial to reduce the complexity of the test system when the eddy current method detects stress and strain, and is beneficial to improve the accuracy of the stress and strain detection results.

Description of drawings

FIG. 1 is a structural diagram 1 of an embodiment of the present invention.

FIG. 2 is a second structural diagram of an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a right-angle meandering fancy eddy current sensor for detecting stress and strain, the eddy current sensor includes a printed circuit board and a coil group on the printed circuit board. The printed circuit board can choose a flat printed circuit board or a flexible printed circuit board. The coil set includes a right-angle meandering fancy excitation coil and a plurality of detection coils arranged in different directions. The main body of the excitation coil is composed of two sides of a right angle and a broken line in the two sides. The broken line divides the angle between the two right-angled sides into two angles, and these two angles can be selected according to needs, usually 45 degrees. The bisector of the angle, the two straight sides and the folded side both include a serpentine folded line. Because the overall shape is a right-angled flower shape, the excitation coil is called a right-angled serpentine fancy excitation coil.

The coil set includes an excitation coil and a detection coil. When an alternating current is connected to the excitation coil, an eddy current will be induced on the structure under test.

Specifically, the coil set includes:

(1) The right-angle excitation coil is wound with a wire. The right-angle excitation coil includes the horizontal and vertical sides forming a right angle, and the folded edge, the horizontal edge, the vertical edge and the folded edge formed at a certain angle with the two sides of the right angle. Each edge of the device includes a meandering fold line composed of at least one meandering unit perpendicular to the edge, and a plurality of meandering units are connected in series. The wire wound into the excitation coil may be one or a plurality of wires wound in parallel.

(2) Also includes a detection coil wound in the meandering line gap of each side. At least one set of detection coils is arranged in each meandering line, and each set of detection coils is wound in at least one meandering unit, and each detection coil is formed by winding at least one wire. Winding in parallel. The meandering interval of the detection coil should be smaller than the meandering interval of the excitation coil, so as to ensure that the meandering unit of the detection coil can be arranged in the return gap of the meandering unit of the excitation coil. The detection coil can be arranged in the form of a zigzag line formed by connecting a plurality of serpentine units end to end in series, so as to improve the sensitivity of the sensor.

The number of detection coils can be three, and at this time, each coil is a group, which are respectively arranged in the foldback gap of a certain section of the zigzag line of the excitation coil, and can be the same as the foldbacks arranged in the two sides of the right angle of the sensor excitation coil. In the gap, or the same is arranged in the folded gap outside the two sides of the right angle.

The number of detection coils may be six, and two are a group, and the two detection coils of the same group are respectively arranged on the left and right sides of the return gap of a certain section of the zigzag line of the excitation coil. If necessary, the superposition of the two detection signals in the same group can be realized by changing the routing method of the coils in each group, or by connecting the external leads on the pads, so as to increase the output signal. At this time, each group of detection coils includes at least two, one detection coil is wound in the gap on the same side of the series meandering unit, and the other detection coil is wound in the gap on the other side of the series meandering unit. Further, when there are many serpentine units, there may be more than one detection coil wound on the same side of the multiple serpentine units, and the detection coils may be wound in each serpentine unit, or may be wound in some serpentine units. A detection coil is wound, and at least two detection coils wound on the same side of a plurality of serpentine units are connected in series or connected to external detection equipment respectively. Multiple detection coils connected in series can improve the detection sensitivity of the sensor, and the number of meandering units can be set according to different situations and different measurement requirements.

The distance between the detection coil wound in the serpentine unit on each side and the wire forming the serpentine unit satisfies that when the power is turned on, the detection coil can detect the eddy current change information excited by the wire forming the serpentine unit.

When necessary, excitation coils with corresponding positions and the same shape can be set on multiple layers of the printed circuit board. holes are connected. This method can increase the eddy current density per unit detection area, thereby improving the sensitivity of stress detection. The detection coils can also be in the form of arranging detection coils with corresponding positions and the same shape on multiple layers of the same circuit board, and the detection coils on different layers are connected in series. The wiring method of the two-layer detection coils connected in series before and after is the same as the method of arranging the series excitation coils on multiple layers of the same circuit board.

The detection coil and excitation coil are preferably located on different layers of the same circuit board. When located on the same layer, make sure that the detection coil and excitation coil do not intersect.

In the sensor of the present invention, an alternating current is connected to the excitation coil, and an eddy current will be induced on the measured structure. The detection coil is also in the form of a serpentine folded line, and is divided into three groups, which are respectively arranged in the return gap of a certain serpentine folded line of the excitation coil. Since the eddy current is affected by the stress in the metal structure, the eddy current excited by the three serpentine broken lines of the excitation coil is respectively sensitive to the stress change in a certain direction. The impedance or output signal of each set of detection coils reflects stress information in a particular direction. By analyzing the impedance changes or output signals of the three sets of detection coils, the component stresses and line strains in three different directions in the metal structure can be detected.

As an embodiment, FIG. 1 of the present invention uses a single-layer printed circuit board to manufacture the eddy current sensor provided by the present invention.

As shown by the thick solid line in Figure 1, each serpentine line of the excitation coil in this embodiment is formed by five serpentine units in series, and the excitation signal is connected by the pad in the lower right corner and the pad on the bisector of the right angle. enter.

As shown by the thin solid line in Fig. 1, there are 6 detection coils in this embodiment, among which, the detection coil 1, the detection coil 3 and the detection coil 5 each have five meandering units connected in series, the detection coil 2, the detection coil 4 and the detection coil 6 each have four serpentine units connected in series. Both ends of each detection coil have a pad for outputting detection signals. A set of detection coil 1 and a set of detection coil 2, a set of detection coil 3 and a set of detection coil 4, and a set of detection coil 5 and a set of detection coil 6.

In this sensor solution, the output signals of the two detection coils of each group of detection units can be superimposed through the external leads of the detection coil pads, so as to increase the overall output signal.

In this sensor solution, each meandering unit of the excitation coil has a longer routing length perpendicular to the routing direction before starting the section of meandering routing, and runs parallel to the routing direction before the section of meandering routing. The length of the line is short, so the eddy current excited by the three meandering lines of the sensor is sensitive to the two sides perpendicular to the overall right angle of the excitation coil and the stress change perpendicular to the direction of the right angle bisector, respectively. Each group of detection coils picks up the corresponding eddy current change information, and reflects the stress and strain changes in the respective sensitive directions in the form of changes in the impedance of the detection coils or changes in the amplitude and phase of the output signal.

The invention also provides a winding method of the right-angle meandering fancy eddy current sensor for detecting stress and strain. Including the winding method of the excitation coil and the winding method of the detection coil.

As shown in Figure 2, the winding method of the excitation coil is:

Walk along the edge a from the starting point S1, after walking the distance da1, wind the zigzag line, after the winding of the zigzag line is completed, continue to walk the distance da2, bend 90° to the side b, continue to trace the distance db1, and wind After winding the winding line, continue to walk the distance db2, and then bend a certain angle within the right angle range formed by side a and side b, continue to route the distance dc3, and then go to the two sides of the right angle. Bend the edge d at a certain angle, continue to route the distance dd1, and wind the zigzag line. After the winding of the zigzag line is completed, continue to route the distance dd2 to reach the end point S2.

The above-mentioned side d bisects the right angle, or it can be unequally divided, and the angle can be set as needed, but the subsequent data analysis will be slightly more complicated.

The winding method of the meandering line is:

S1: Line distance D1 along the direction perpendicular to the edge of the meandering fold line, where D1 is the unit length of the meandering unit;

S2: From the current position, after bending 90° in the direction away from the starting point S1, run the line D2 again along the bending direction, and this D2 is the width I of the meandering unit;

S3: From the current position, bend 90 degrees to the direction of the triangle side where the meandering line is located, and route line D1 along the bent direction;

S4: From the current position, bend 90 degrees away from the starting direction S1, and route the line D3 along the bent direction to complete the routing of a meandering unit; this D3 is the width II of the meandering unit;

S5: Multiple meander units are connected in series to form meander lines.

The above method is only one embodiment of the present invention, and the present invention may also have other embodiments.

As shown in Figure 2, it is the routing steps of each section of the zigzag line of an excitation coil of the present invention: (1) Preparation stage: 1. The starting point of the section of the serpentine line is referred to as the starting point of the section, Bend 90 degrees at the meandering line from the starting point, and route the line in the direction after bending to a suitable length D1/2 mm. Here, the length D1 is recorded as the unit length of the meandering line; ② From the current position , bend 90 degrees in the direction away from the starting point, and route the line to a suitable length D2 in the direction after the bending, and the appropriate length D2 is recorded as the unit width of the meandering line; : ① From the current position, bend 90 degrees in the direction of returning to the starting point, and route D1 mm in the direction after bending; ② From the current position, bend 90 degrees in the direction away from the starting point, along the direction after bending Route the line D2 mm; ③ From the current position, bend 90 degrees in the direction of returning to the starting point, and route the line D1 mm in the direction after bending; ④ From the current position, bend 90 degrees away from the starting point, and follow the bend The folded direction is routed by D2 mm, and the routing of a meandering unit is now completed; (3) meandering unit cycle routing stage: If you need to use N meandering units in series in the sensor, you can repeat the steps (3) at the current position. ) content N times; if the sensor only needs one meandering unit, this step can be ignored; (4) End stage: bend 90 degrees from the current position to the direction of returning to the starting point, and walk in the direction after bending Line D1/2 mm, and then bend it at a 90-degree angle away from the starting point to continue the following traces.

On each side of the excitation coil, a detection coil is wound from the starting position in the serpentine unit gap on one side of the zigzag line, or a detection coil is wound in the gap on both sides of the serpentine unit; the detection coil is A serpentine line having a distance from the serpentine fold line of the excitation coil.

As shown in FIG. 2 , the serpentine fold line of the detection coil 1 is located on the upper side of the serpentine fold line on the side a, and the serpentine unit of the detection coil is arranged in the gap of each serpentine unit, and each serpentine unit is connected in series connect. The serpentine fold line of the detection coil 2 is located on the lower side of the serpentine fold line on the side a, and the serpentine unit of the detection coil is arranged in the gap outside each serpentine unit, and the serpentine units are connected in series.

The width I and width II of the excitation coil and the same meandering element are the same or different. The detection coil needs to be meanderingly arranged in the meandering zigzag line gap of the excitation coil. Therefore, when a detection coil is wound in the gap on the same side of at least one meandering unit, the width I and width of the same meandering unit of the detection coil are The lengths of II are different to ensure a certain distance between the detection coil and the excitation coil.

The above-mentioned winding method is only an embodiment of the present invention. During the specific winding, the starting point position and the winding direction can be set as required, as long as the final winding structure conforms to the structure of the present invention, that is, the above The starting position and the winding direction in the winding method do not limit the present invention.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, some changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the present invention. scope of protection.

Claims (7)

1. A right-angle type meandering flower type eddy current sensor is characterized in that: the coil assembly comprises a printed circuit board and a coil assembly printed on the printed circuit board;

the coil assembly includes:

the rectangular excitation coil comprises a transverse edge and a vertical edge which form a right angle, and a folded edge which forms a certain angle with two edges of the right angle, wherein the transverse edge, the vertical edge and the folded edge respectively comprise a meandering line which is vertically arranged with the edge, the meandering line comprises at least one meandering unit, and a plurality of meandering units are connected in series;

the detection coil is wound in the zigzag line gap on each side, and each group of detection coils is wound in at least one zigzag unit;

excitation coils with corresponding positions and the same shape can be arranged on a plurality of plate layers of the printed circuit board, and the excitation coils on different plate layers are connected in series;

detection coils with corresponding positions and the same shape can be arranged on a plurality of plate layers of the printed circuit board, and the detection coils on different plate layers are connected in series; the two layers of coils which are connected in series in front and back are both wired clockwise or counterclockwise and connected by via holes;

the excitation coil and the detection coil are positioned on the same slab or different slabs; when located on the same layer, the detection coil does not intersect with the excitation coil;

each group of detection coils comprises at least two independent detection coils, wherein one detection coil is wound in the gap on one side of the zigzag line, and the other detection coil is wound in the gap on the other side of the zigzag line.

2. A right-angled serpentine eddy current sensor, as set forth in claim 1, wherein:

the distance between the detection coil wound in the winding unit of each side and the conducting wire forming the winding unit satisfies the following conditions: when the current is applied, the detection coil can detect the eddy current change information excited by the conducting wire forming the winding unit.

3. A right-angled serpentine eddy current sensor, as set forth in claim 1, wherein:

the coiling is no less than one at the independent detection coil that meanders the broken line homonymy, and the detection coil that meanders in the unit clearance is non-closed rectangle, and two at least independent detection coils of same meanders the broken line homonymy coiling can connect in series or connect external detection equipment respectively.

4. A right-angled serpentine eddy current sensor, as set forth in claim 1, wherein:

the right angle is divided into two 45-degree angles by the folded edge.

5. A method for winding a coil of a right-angle meander type eddy current sensor as set forth in any one of claims 1 to 4, wherein: the method comprises an excitation coil winding method and a detection coil winding method; the edges a and b of the right-angle type are set as right-angle edges, the edge c is a folded edge,

the winding method of the exciting coil comprises the following steps:

routing from a starting point S1 along an edge a, after a distance da1 is passed, winding a meandering folding line, after the winding of the meandering folding line is finished, continuously routing a distance da2, bending for 90 degrees to an edge b, continuously routing a distance db1, winding the meandering folding line, after the winding of the meandering folding line is finished, continuously routing a distance db2, after the bending for a certain angle is carried out in a right-angle range formed by the edge a and the edge b, continuously routing a distance db3, further bending to an edge d forming a certain angle with two right-angled edges, continuously routing a distance dd1, winding the meandering folding line, after the winding of the meandering folding line is finished, continuously routing a distance dd2, and reaching a terminal point S2;

the detection coil winding method comprises the following steps:

winding a detection coil in the gaps of the meandering units on one side of the meandering line from the starting position on each side of the excitation coil, or respectively winding a detection coil in the gaps on both sides of the meandering units; the detection coil is a meandering line having a certain distance from a meandering line of the excitation coil.

6. The coil winding method of the right-angled serpentine eddy current sensor according to claim 5, wherein:

the winding method of the meandering fold line comprises the following steps:

s1: routing a distance D1 in a direction perpendicular to the side of the serpentine fold line, D1 being the cell length of the serpentine cell;

s2: d2 is routed again along the direction after bending the current position by 90 degrees in the direction away from the starting point S1, wherein D2 is the width I of the serpentine unit;

s3: from the current position, bending the wire by 90 degrees in the direction of the triangle side where the previous section of the meandering fold line is positioned, and routing the wire D1 in the bent direction;

s4: bending the current position to a direction S1 far away from the starting direction by 90 degrees, and routing D3 along the bent direction to complete routing of one serpentine unit; d3 is the width II of the serpentine element;

s5: the plurality of meandering units are connected in series to form a meandering line.

7. The coil winding method of the right-angled meandering flower type eddy current sensor as claimed in claim 6, wherein:

the width I and the width II of the same meandering unit of the exciting coil are the same or different;

when a detection coil is wound in the gap of at least one winding unit of the excitation coil, the width I and the width II of the same winding unit of the detection coil are different in length.

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