Pipeline welding seam array type detection device based on tangential eddy current

Abstract

The utility model discloses a pipeline welding seam array type detection device based on tangential eddy current. The pipeline welding seam array type detection device comprises a detection probe module, a signal excitation and acquisition module and a signal processing module, the detection probe module comprises a flexible probe unit, the flexible probe unit comprises a plurality of tangential eddy current probes, each tangential eddy current probe comprises an excitation coil and two detection coils, and the excitation coils and the detection coils are coaxially and orthogonally distributed; the axis of the tangential eddy current probe and the surface of the weld form an included angle of 0-20 degrees, the excitation magnetic field is tangentially distributed along the weld, and the eddy current field is perpendicular to the weld and penetrates through the inside. By means of tangential eddy current excitation and multi-channel signal fusion, the device has the advantages of eliminating interference of weld reinforcement on detection signals and improving defect recognition capacity.

Description

TECHNICAL FIELD

[0001] The utility model relates to nondestructive testing technical field especially a kind of pipeline weld array detection device based on tangential eddy current. BACKGROUND

[0002] Pipeline weld eddy current detection is susceptible to weld reinforcement (i.e. weld surface protrusion). Traditional eddy current probe uses vertical excitation, and the reinforcement causes uneven contact between the probe and the weld surface, resulting in lift-off effect interference, masking the small defect signal and reducing the detection sensitivity.

[0003] In the prior art, two methods are usually used to partially alleviate the interference: mechanical polishing to remove the reinforcement or low-frequency eddy current technology. However, the former method is inefficient and can damage the integrity of the weld, and the latter method has insufficient detection resolution.

[0004] Therefore, there is an urgent need for a detection technology that can suppress reinforcement interference without damaging the weld. SUMMARY

[0005] The utility model aims at providing a kind of pipeline weld array detection device based on tangential eddy current. The utility model has the advantages of eliminating the interference of weld reinforcement on detection signal and improving defect recognition capability by tangential eddy current excitation and multi-channel signal fusion.

[0006] The technical scheme of the utility model: a kind of pipeline weld array detection device based on tangential eddy current, including detection probe module, signal excitation and acquisition module and signal processing module;The detection probe module includes a flexible probe unit, and the flexible probe unit includes a plurality of tangential eddy current probes, each tangential eddy current probe includes an excitation coil and two detection coils, and the excitation coil and the detection coil are coaxially and orthogonally distributed;The axis of the tangential eddy current probe forms an angle of 0-20° with the weld surface, and the excitation magnetic field is distributed along the tangential direction of the weld, and the eddy current field is perpendicular to the weld and penetrates the interior.

[0007] In the foregoing pipeline weld array detection device based on tangential eddy current, the flexible probe unit further includes a substrate and a protective film disposed below the substrate, and the tangential eddy current probes are distributed on the substrate;The excitation coils are spaced apart and disposed in the substrate, and the detection coils are disposed between the substrate and the protective film and correspond to the excitation coils;The detection coils are made of flexible circuit board printed flat coils and are pasted in multiple layers.

[0008] In the foregoing tangential vortex-based pipeline weld array detection device, the detection probe module further comprises a support, magnets arranged below both ends of the support, rollers rotatably arranged outside the magnets, and photoelectric encoders arranged outside some of the rollers; the flexible probe unit is arranged below the middle part of the support, a pressure sensor is arranged above the flexible probe unit, and a constant-pressure spring connected with the support is arranged on the pressure sensor; the photoelectric encoders are coaxially arranged with the rollers.

[0009] In the foregoing tangential vortex-based pipeline weld array detection device, the tangential vortex probes are arranged in multiple numbers, the number of the tangential vortex probes corresponds to the weld width, and the tangential vortex probes are arranged in an arc linear array along the axial direction of the weld, so that the weld can be effectively covered; the tangential vortex probes are arranged in a staggered manner, specifically, odd-numbered tangential vortex probes are offset by +1.5 mm, and even-numbered tangential vortex probes are offset by -1.5 mm.

[0010] In the foregoing tangential vortex-based pipeline weld array detection device, the signal excitation and collection module comprises a multi-channel excitation circuit and a signal collection unit; the multi-channel excitation circuit is correspondingly connected with the excitation coil and comprises an FPGA, a DAC, a multi-way switch and an H-bridge power amplifier connected in sequence; the FPGA controls the multi-way switch to activate the excitation coil in sequence; and the excitation coil is further connected with an LC resonant circuit in series.

[0011] In the foregoing tangential vortex-based pipeline weld array detection device, the signal collection unit is correspondingly connected with the detection coil and comprises a multi-way switch, a preamplifier, a filter, a synchronous demodulator, an ADC and a CPU connected in sequence.

[0012] Compared with the prior art, the utility model has the advantages of:

[0013] 1. Tangential magnetic field excitation combined with array layout effectively suppresses the lift-off effect caused by the weld reinforcement and reduces the interference on detection;

[0014] 2. Multi-channel excitation circuit is adopted to drive each probe unit in time division mode to generate a tangential vortex field; and electronic scanning greatly improves the detection efficiency;

[0015] Therefore, the utility model has the advantages of eliminating the interference of the weld reinforcement on the detection signal and improving the defect recognition capability by means of tangential vortex excitation and multi-channel signal fusion. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the principle schematic view of the detection device of the utility model;

[0017] Figure 2 is the structure schematic view of the excitation coil and the detection coil in the detection device of the utility model;

[0018] Figure 3 is the structural schematic view of the flexible probe unit in the detection device of the utility model;

[0019] Figure 4 is the weld coverage schematic view of the flexible probe unit in the detection device of the utility model;

[0020] Figure 5 is the structural schematic view of the detection probe module in the detection device of the utility model;

[0021] Figure 6 is the structural schematic view of the signal excitation and collection module in the detection device of the utility model.

[0022] The marks in the drawing: 1, support; 2, flexible probe unit; 21, base material; 22, excitation coil; 23, detection coil; 24, protective film; 3, photoelectric encoder; 4, roller; 5, magnet; 6, pressure sensor; 7, constant pressure spring; 8, test piece; 9, weld. DETAILED DESCRIPTION

[0023] The utility model will be further explained in connection with the drawing and example, but not as the basis for limiting the utility model.

[0024] Example. One kind is based on tangential eddy current's pipeline weld array type detection device, as shown in Figure 1 And 2 It includes detection probe module, signal excitation and collection module and signal processing module;The detection probe module includes flexible probe unit 2, and the flexible probe unit 2 includes multiple tangential eddy current probes, and each tangential eddy current probe includes excitation coil 22 and 2 detection coils 23, and excitation coil 22 and detection coil 23 are coaxial orthogonal distribution;The axis of the tangential eddy current probe is 0-20 ° included angle with the surface of weld 9, and excitation magnetic field is along the tangential distribution of weld 9, and eddy current field is perpendicular to weld 9 and penetrates inside;

[0025] The setting of tangential eddy current probe makes the surface residual height wave interference of weld 9 same with the direction of eddy current, and the influence on eddy current is small, and this interference signal is effectively suppressed.

[0026] The diameter of excitation coil 22 is 5mm, and the number of turns is 50, and the diameter of detection coil 23 is 2mm, and the number of turns is 20.

[0027] As shown in Figure 3As shown in the figure, the flexible probe unit 2 further comprises a base material 21 and a protective film 24 arranged below the base material 21, and the tangential vortex probes are arranged on the base material 21; the excitation coils 22 are arranged in the base material 21 at intervals, and the detection coils 23 are arranged between the base material 21 and the protective film 24 and correspond to the excitation coils 22; the detection coils 23 are printed flat coils on a flexible circuit board and are pasted in multiple layers to ensure the consistency of the parameters of the detection coils 23.

[0028] The base material 21 is a flexible silica gel base material with a thickness of 3 mm, and the interval of the excitation coils 22 is 2 mm

[0029] As shown in the figure, Figure 5 The detection probe module further comprises a bracket 1, magnets 5 arranged below both ends of the bracket 1, rollers 4 rotatably arranged outside the magnets 5, and photoelectric encoders 3 arranged outside some of the rollers 4; the flexible probe unit 2 is arranged below the middle part of the bracket 1, a pressure sensor 6 is arranged above the flexible probe unit 2, and a constant pressure spring 7 connected to the bracket 1 is arranged above the pressure sensor 6; the photoelectric encoders 3 are coaxially installed with the rollers 4.

[0030] The flexible probe unit 2 is installed on the bracket 1 and can effectively adapt to test pieces 8 of different pipe diameters (Φ200mm-Φ1200mm); the magnets 5 are permanent magnets and can be conveniently adsorbed on ferromagnetic material pipes to ensure that they do not leave the surface of the pipes during movement; to further ensure that the detection probe module can move smoothly, the rollers 4 are arranged and a gap of 0.1 mm is reserved between the magnets 5 and the test pieces 8; the pre-pressure of the pressure spring 7 is 15 N, which ensures good contact between the flexible probe unit 2 and the surface of the test piece 8 and maintains appropriate pre-pressure; the pressure sensor 6 has a range of 0-30 N and an accuracy of ±0.5 N, is embedded in the base of the flexible probe unit 2, and sends pressure data in real time; the photoelectric encoders 3 measure the rotational speed of the rollers 4 and thus determine the spatial position information of the flexible probe unit 2.

[0031] As shown in the figure, Figure 4 The tangential vortex probes are arranged in an arc linear array along the axis direction of the weld 9, covering the weld 9 and a heat-affected zone of 15 mm on both sides; the tangential vortex probes are arranged in a staggered manner, specifically, the odd-numbered tangential vortex probes are offset by +1.5 mm, and the even-numbered tangential vortex probes are offset by -1.5 mm, achieving 100% coverage without blind area.

[0032] As shown in the figure, Figure 6 The signal excitation and collection module comprises a multi-channel excitation circuit and a signal collection unit; the multi-channel excitation circuit is correspondingly connected to the excitation coils 22 and comprises an FPGA, a DAC, a multi-way switch, and an H-bridge power amplifier connected in sequence; the FPGA controls the multi-way switch to activate the excitation coils 22 in sequence; the excitation coils 22 are also connected in series with an LC resonant circuit.

[0033] Time-sharing drive: 8-channel excitation source is controlled by FPGA, each channel outputs 200 kHz sine wave with 200 mA peak current, and is driven by H-bridge power amplifier to ensure current stability fluctuation < ± 2%; FPGA controls multi-channel switch to activate tangential eddy current probe T1→T2→…→T8 in sequence, each channel excitation duration is 9 ms, such as Figure 6 ; 1 ms silent period is inserted between adjacent channel excitation to avoid cross interference.

[0034] Impedance matching: LC resonant circuit in series with each channel, inductance 1 μH, capacitance 10 nF, to improve excitation efficiency.

[0035] The signal acquisition unit is connected with the detection coil 23, and includes a plurality of switches, a preamplifier, a filter, a synchronous demodulator, an ADC and a CPU connected in sequence.

[0036] The detection coil 23 is connected in a differential mode, and the detection coil is connected in a differential mode;

[0037] The preamplifier amplifies the microvolt-level signal of the detection coil 23 by 100 times, and the bandwidth is 1 MHz;

[0038] The 4th order Butterworth filter has a center frequency of 200 kHz and a bandwidth of ± 5 kHz, and can suppress power frequency noise and high frequency interference.

Claims

1. A tangential vortex based pipe weld array inspection apparatus, characterized by: The device comprises a detection probe module, a signal excitation and collection module and a signal processing module; the detection probe module comprises a flexible probe unit (2), which comprises a plurality of tangential eddy current probes, each of which comprises an excitation coil (22) and two detection coils (23), and the excitation coil (22) and the detection coil (23) are coaxially and orthogonally distributed; the axis of the tangential eddy current probe forms an angle of 0-20° with the surface of the weld (9), the excitation magnetic field is distributed tangentially along the weld (9), and the eddy current field is perpendicular to the weld (9) and penetrates the interior.

2. A tangential vortex based pipe weld array inspection apparatus as claimed in claim 1, wherein: The flexible probe unit (2) further comprises a base material (21) and a protective film (24) arranged below the base material (21), and the tangential eddy current probes are arranged on the base material (21); the excitation coil (22) is arranged in the base material (21) with an interval, and the detection coil (23) is arranged between the base material (21) and the protective film (24) and corresponds to the excitation coil (22); the detection coil (23) is a flexible circuit board printed flat coil and is pasted in multiple layers.

3. A tangential vortex based pipe weld array inspection apparatus as claimed in claim 1, wherein: The detection probe module further comprises a bracket (1), magnets (5) arranged below both ends of the bracket (1), rollers (4) rotatably arranged outside the magnets (5), and photoelectric encoders (3) arranged outside some of the rollers (4); the flexible probe unit (2) is arranged below the middle part of the bracket (1), a pressure sensor (6) is arranged above the flexible probe unit (2), and a constant pressure spring (7) connected with the bracket (1) is arranged on the pressure sensor (6); the photoelectric encoder (3) is coaxially installed with the roller (4).

4. A tangential vortex based pipe weld array inspection apparatus as claimed in claim 1, wherein: The tangential eddy current probes are arranged in a plurality of arrays, the number of the tangential eddy current probes corresponds to the width of the weld (9), and the tangential eddy current probes are arranged in an arc linear array along the axis direction of the weld (9); the tangential eddy current probes are arranged in a staggered manner, specifically, the odd-numbered tangential eddy current probes are offset by +1.5 mm, and the even-numbered tangential eddy current probes are offset by -1.5 mm.

5. A tangential vortex based pipe weld array inspection apparatus as claimed in claim 1, wherein: The signal excitation and collection module comprises a multi-channel excitation circuit and a signal collection unit; the multi-channel excitation circuit is correspondingly connected with the excitation coil (22) and comprises an FPGA, a DAC, a multi-channel switch and an H-bridge power amplifier connected in sequence; the FPGA controls the multi-channel switch to activate the excitation coil (22) in sequence; the excitation coil (22) is further connected in series with an LC resonant circuit.

6. A tangential vortex based pipe weld array inspection apparatus as claimed in claim 5, wherein: The signal collection unit is correspondingly connected with the detection coil (23) and comprises a multi-channel switch, a preamplifier, a filter, a synchronous demodulator, an ADC and a CPU connected in sequence.

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